KORBA SIMULATOR

1

KORBA SIMULATOR

2

KORBA SIMULATOR

3

FOREWORD

Power is the most vital necessity for industrial and economical growth of any nation. Electricity can bring sea changes in quality of life of its society members. NTPC in its endeavour for becoming most significant entity once again after 30 years of untiring and relentless efforts, reaffirm its commitment towards making India a self-reliant nation in the field of power generation. Having proven excellence in Operation & Maintenance of 200 and 500MW units; for the first time we are going ahead with the commissioning of 660MW units at our Sipat Project. This is a major step towards technological advancement in power generation. In the present time, efficient and economical power generation is the only answer to realise our ambitious plan. It is the need of the hour that available human resources who are the at the whelm of the affairs managing the large thermal power plants having sophisticated technology and complex controls, is to be properly channelised and trained. NTPC management firmly believes that skill and expertise up-gradation is a continuous process. Therefore, training gets utmost priority in our company. Power Plant Simulators are the most effective tools ever created. This has computer based response, creation incorporating mathematical models to provide real time environment, improves retentivity and confidence level to an optimum level in a risk-free, cost and time effective way.To supplement the hands-on training on panel and make the training more effective an operation manual in two volumes has been brought out. The operation manual on 500MW plant provide the information comprehensively covering all the aspects of Power Plant Operation which can be useful for fresh as well as experienced engineers. It provides a direct appreciation of basics of thermal power plant operation and enables them to take on such responsibility far more sincerely and effectively. I am pleased to dedicate these manuals (volume- I & II), prepared by CSTI members which is a pioneer institute covering more than 7000 participants till date, to the fraternity of engineers engaged in their services to power plant. The volume-I deals with the Plant & system description and II covers the operating instruction in a lucid way. I sincerely hope that readers will find these manuals very useful and the best learning aid to them. I believe that in spite of all sincere efforts and care of faculty members & staff, some area of improvement might have remained unnoticed. Hence, your valuable suggestions and comments will always be well received and acted upon.

( A. CHAUDHURI )

GENERAL MANAGER

KORBA SIMULATOR

4

KORBA SIMULATOR

5

CONTENTS

CHAPTER

NO. TOPIC PAGE NO

1. UNIT COLD START-UP PROCEDURE 7-115

2. UNIT HOT START-UP PROCEDURE 117-127

3. SHUTDOWN PROCEDURE 129-148

4. FURNACE SAFEGUARD AND SUPERVISORY SYSTEM 149-198

5. PROTECTION AND INTERLOCKS 199-222

6. ANALOG CONTROL SYSTEM 223-233

7. AUTOMATIC TURBINE RUN-UP SYSTEM (ATRS) 235-270

8. ELECTRICAL PROTECTIONS 271-284

9. POWER PLANT CHEMISTRY 285-293

10. EMERGENCY HANDLING 295-305

11. LIST OF MALFUNCTION 307-318

KORBA SIMULATOR

6

KORBA SIMULATOR

7

COLD START-UP PROCEDURE

KORBA SIMULATOR

8

KORBA SIMULATOR

9

CHARGING OF ELECTRICAL SYSTEM 1. Ensure electrical supply to C.W. Pumps and other associated auxiliaries are

available.

2. Charge Station Transformer TOC or TOD and respective station buses SE/SF.

3. Ensure that all the electrical breakers are racked IN and OFF Service mode.

4. Ensure that D.C. Supply to all the breakers is available.

5. Charge Unit Bus A/B through Station Bus SE.

6. Charge Unit Service Switch Gear, Emergency Bus through normal Breaker.

7. Ensure that supply is available to various MCCs, (Turbine MCC, Boiler MCC,

TVDC, BVDC, Lub oil MCC).

8. Charge ESP and Ash Handling Transformers.

9. Ensure that supply is available to all Electrical Buses.

10. Check Unit Bus Voltage, Voltage can be adjusted by changing the tap position

of Station Transformer.

11. Normalise MDBFP Breaker through Station Bus SF. CHARGING OF EMERGENCY BUS THROUGH D.G. SET 1. Check the D.G.Set physically for fuel level, oil, cooling water. 2. Control supply and starter motor D.C. voltage are O.K. 3. Start D.G.Set from CSSAEP (Common Services Supply Auxiliaries Equipment

Panel).

4. Adjust the voltage/Frequency by using switches provided in the panel. 5. Put the Synchroniser on manual. 6. Close the D.G.Set Breaker to Emergency Bus. 7. Check the D.G.Set for any abnormality.

KORBA SIMULATOR

10

CHARGING OF AUXILIARY STEAM HEADER OBJECTIVE

• To line up and charge auxiliary steam header and charge steam to various equipments.

PRE - REQUISITES & STATE OF PLANT 1. Work permit on 16 ata header, auxiliary PRDS and associated system such as

SCAPH, atomising steam, HFO heater, etc., cancelled and men, material

removed from these areas.

2. All drains and manholes are closed and the equipment and system are in

service worthy condition.

3. All level gauges, indicating instruments, pressure and flow switches and other

Protective devices are lined up for services.

4. 415 V supply available to valve actuators.

5. 220 V DC supply available.

6. Control panel supply available 7. UCB instruments for boiler side available. 8. Service air and instrument air is charged. 9. PRE - START CHECKS AND LINE UP 10. Ensure the output of primary and secondary RAPH A/B cold end temperature

control valves are closed.

11. Ensure the Dearator pressure control by auxiliary steam control valve is closed. 12. Auxiliary steam header pressure and temperature controller are closed. 13. Open the auxiliary steam header drain valve from local. 14. Ensure all the manual isolating valves to fuel oil tank heating, burner

atomising, SCAPHs, etc. are close.

15. Ensure the motorised steam isolation valves to BFP and deaerator (ASL-004

and ASL-006) are closed.

16. Ensure the gland sealing steam valve ASH-006 is in closed condition. 17. Ensure the existing 200 MW unit auxiliary steam is available and inform UCB

KORBA SIMULATOR

11

personnel.

18. Ensure the cold reheat to auxiliary steam block valve ASH - 001 is closed if not turn the switch to close position till green light comes.

OPERATIONAL STEPS 1. Open the auxiliary steam interconnection form existing 200 MW unit 16 ata header to charge the auxiliary steam header. 2. Check the pressure and temperature of the 16 ata header comes to normal. 3. Open the primary and secondary SCAPH A or B inlet and outlet isolating

valves.

4. Open the deaerator pegging motorised valve ASL - 006. 5. Open the gland steam supply valve ASH-006. 6. Close the drain of the 16 ata header from local.

*Auxiliary Steam Header is Charged*

KORBA SIMULATOR

12

AU

XIL

IAR

Y S

TE

AM

SY

ST

EM

KORBA SIMULATOR

13

KORBA SIMULATOR

14

CHARGING OF RAW COOLING WATER (ARCW) SYSTEM. OBJECTIVE

• To line up and start the auxiliary raw cooling water pumps.

• To charge the auxiliary raw cooling water to various equipments. PRE - REQUISITES & STATE OF PLANT 1. Work permit on circulating water duct, auxiliary cooling water pump, plate

type heat exchanger and associated system cancelled.

2. All level gauges, indicating instruments, pressure and flow switches and other protective devices are lined up for service. 3. All filters and coolers are cleaned and necessary lubrication of equipment’s are

done.

4. 415 V supply available for LT drives , valves & actuators. 5. Control panel supply is available. 6. 6.6KV switch gear charged and breakers are kept in service mode. 7. Circulating water (CW) pumps are running and CW duct is charged PRE - START CHECKS AND LINE UP 1. Ensure that suction valve for all three pumps are open from local. 2. Check that the gland sealing is in service (i.e.sealing water valves are open), bearing lubrication is satisfactory, pump rotor is free. 3. Close the pump drain and open the vent to ensure no air is coming. 4. Line up the discharge filter by opening the isolating valves. 5. Ensure that isolating valves for the plate type heat (PHE) exchangers are open to CW discharge seal pit. 6. Ensure the recirculation valve is opened. 7. Ensure the motorised discharge valves for all three pumps are closed from

KORBA SIMULATOR

15

CSSAEP. 8. Ensure that the EPB (Emergency push button) is released from local. OPERATIONAL STEPS 1. Change the selector switch to A position. 2. Start ARCW pump Amotor by turning the hand switch position to on and

release it.

3. Check the starting current and discharge pressure. 4. The pump discharge valve will start opening and red light will come indicating discharge valve has fully opened. 5. Close the recirculation valve from local once the discharge valve is fully

opened.

6. Check the return flow of the raw cooling water in the CW discharge seal pit. 7. Check the differential pressure across the discharge strainer. 8. Ask local operator to check for any abnormal sound from the motor or pump 9. Check the bearing temperatures

*ARCW pump is in service*

KORBA SIMULATOR

16

AU

XIL

IAR

Y R

AW

CO

OLIN

G W

AT

ER

SY

ST

EM

KORBA SIMULATOR

17

CHARGING OF EQUIPMENT COOLING WATER (ECW) SYSTEM OBJECTIVE • To line up and start equipment cooling water pumps. • To charge the equipment cooling water to various equipment. PRE - REQUISITES & STATE OF PLANT 1. Work permit on equipment cooling system overhead DM water tank, boiler

feed pump coolers, auxiliary coolers for generator package, fan coolers, etc.,

cancelled.

2. All level gauges, indicating instruments, pressure and flow switches are lined

up.

3. All the filters and coolers are cleaned and necessary lubrication of equipment

are done.

4. 415V supply available for LT drives valves & actuators. 5. Instrument air and service air is charged to the controllers. 6. ARCW pumps are running normal. 7. Ensure that 6.6 KV switch gear is charged and the breakers are kept in service

mode.

PRE - START CHECKS AND LINE UP 1. Ensure that suction valve for all three pump is open from local. 2. Ensure adequate level in the overhead DM water cooling tank. 3. Check that the gland sealing is in service, bearing lubrication is satisfactory, pump rotor is free. 4. Open the inlet valve to the suction header from the over head DM water

cooling tank.

5. Close the pump drain and open vent to ensure no air is coming. 6. Ensure that isolating valves are open for the plate type heat exchanger which

is already charged from the auxiliary raw cooling water side.

KORBA SIMULATOR

18

7. Ensure the motorised discharge valves for all the three pumps are closed from CSSAEP. OPERATIONAL STEPS 1. Change the selector switch to A position 2. Start ECW pump A motor by turning the hand switch position to on. 3. Check the starting current and discharge pressure. 4. The pump discharge valve to be opened and red light will come indicating discharge valve has fully opened. 5. Maintain the level in the DM water cooling tank by taking additional make up either from DM plant or from CTP(Condensate Transfer Pump), if running. 6. Charge the ECW to various auxiliary coolers and check the differential

pressure is maintained by the control valve, PCV-1145 for Boiler. package,

PCV 1146 for BFP coolers ,PCV - 1144 for CEP, etc.

*ECW pump is in service*

KORBA SIMULATOR

19

EQ

UIP

ME

NT

CO

OLIN

G W

AT

ER

SY

ST

EM

KORBA SIMULATOR

20

START UP OF CONDENSATE SYSTEM OBJECTIVE • To line up and take hot well make up system in service. • To line up and start Condensate Extraction Pumps (CEP) to fill the deaerator. PRE - REQUISITES & STATE OF PLANT 1. Unit ECW system in service. 2. Work permit on various LP heaters, drip system, drain cooler, etc., cancelled

and men, material removed from these areas.

3. Instrument air is charged to various valves and valve actuators. 4. Local pressure, temperature, flow, level gauges & transmitters charged. 5. Check that the hot well drains are closed. 6. Sufficient quantity of DM water available in the unit C.S.T. 7. Ensure that 6.6 KV switch gear is charged and breakers are kept in the service

mode.

8. Ensure that EPB is released from LOCAL. PRE - START CHECK AND LINE UP 1. Establish ECW flow to CEP motor cavity air coolers. 2. Open ECW inlet and outlet valves to CEP bearing oil cooler. 3. Line up the hot well normal make up line from local . 4. Line up the hot well emergency make up line from local . 5. Open the GSC minimum flow isolating valve from local . 6. Ensure that condensate spill valve bypass and condensate fill valves are closed. 7. Open the suction valve for all three CEPS from LOCAL 8. Open the recirculation isolation valve from local . 9. Rack in the CEP breakers from Switch gear in service remote position.

KORBA SIMULATOR

21

10. Open the sealing line valve from common discharge from local . 11. Ensure the common isolation valve for exhaust hood spray and drain manifold

is closed from local .

12. Open the manual isolating valves for Deaerator level controller (CO16, CO17)

from local .

13. Line up the hot well high level controller from local . 14. Ensure the line up of the LP heaters from water side is through upto the deaerator and water side vent is crack open . 15. Ensure all the CEP discharge valves are closed. 16. Ensure that all the recirculation valves are full open and are in manual mode. OPERATION STEPS 1. Change the emergency make - up pump A status from manual to auto mode

from UCB. 2. Check that emergency make - up pump A should start. 3. Start any two hot well make - up pumps from DM plant. 4. Open the hot well make up emergency control valves to fill the hot well. 5. Observe the steady rise in the condensate make - up flow and hot well level. 6. Keep the control mode for emergency make - up pump B in auto.

7. Close both the controllers when hot well level comes to about +50 mm. 8. Check the hot well level adequate permissive appears on all the three CEP start

permissive indication.

9. Check that all permissive lamps are on to start CEP. 10. Start the CEP-A by turning the hand switch to close position and release it. 11. Check that discharge valve opens and discharge pressure gradually builds up.

12. Check that the pump is running OK and no abnormal noise at local. 13. Keep the lead / lag switch of pump B and C to lead and lag mode respectively.

14. Open the block valve of the Deaerator level control valve CO-014 .

KORBA SIMULATOR

22

15. Open the deaerator level control valve to about 20%. 16. Condensate flow to deaerator increases and condensate discharge pressure

drops

17. Check that deaerator level gradually builds up. 18. Open the emergency make- up control valve to make - up hot well level to

normal value.

19. Close the Deaerator level controller once the Deaerator level has come above

normal level.

20. Close the emergency make-up controller as the condensate pump is running on

recirculation only.

21. Check the bearing temperature and vibration of the pump. 22. Keep the block valve of Deaerator level controller B station (CO -17) also in open

state.

*CEP in service *

KORBA SIMULATOR

23

CO

ND

EN

SA

TE

SY

ST

EM

KORBA SIMULATOR

24

MOTOR DRIVEN BOILER FEED PUMP ( BFP - C ) OBJECTIVE

• To line up and take boiler feed pump - in service. PRE - REQUISITES & STATE OF PLANT 1. Unit ECW system in service. 2. Work permit on various HP heaters, drip system, deaerator, etc. cancelled and

men, material removed from these areas.

3. Instrument air is charged to various valves and actuators. 4. Local pressure, temperature, flow, level gauges and transmitters charged. 5. Check that deaerator over flow valve and drain valves are closed. 6. The condensate pump is running on recirculation as per the startup

instruction

7. Check the interlocks of AC & DC LOPs.. PRE - START CHECKS AND LINE UP 1. Establish the ECW flow to the working oil and lub oil coolers. 2. Charge the booster pump mechanical seal coolers. 3. Ensure that seal quench valve is open and seal quench pressure is more than 15 Kg/cm2. 4. Line up the BFP system from local (Lub oil coolers,working oil coolers etc). 5. Open the recirculation valve isolating valve for all the three pumps from local 6. Check that AOP of BFP is taking start from UCB and recirculation valve

controller,scoop controller is operative from UCB

7. Rack in the BFP C breaker from local . 8. Ensure that HP BP desuperheating station manual valve is in close condition 9. Open the BFP A/B/C suction valve from local . 10. Line up the emergency seal quench water pump from local .

KORBA SIMULATOR

25

11. Line up the LP dosing and HP dosing system from local . 12. Ensure that HP heaters are bypassed (valve FW-14 should be opened). Check

the analog indication in UCB.

13. Start the auxiliary oil pump of BFP-C 14. Ensure that all the permissive lamps are ON in the UCB for boiler feed pump C. OPERATIONAL STEPS 1. Check once more the scoop tube controller is minimum and recirculation valve is full open. 2. Start BFP by turning the hand switch to breaker close position and release it. 3. Open the discharge valve of BFP C (FW-13) opens from local 4. Check the BFP discharge pressure and motor current from UCB 5. Ensure that motor cooling water valve has opened on interlock and red lamp is on. 6. Raise the scoop tube position by about 10% to raise the discharge pressure 7. Check the bearing temperature and vibrations from the UCB indicators. 8. Open the HP BP desuperheating station manual valve from local. * MD BFP-C is in service. *

KORBA SIMULATOR

26

FE

ED

WA

TE

R S

YST

EM

KORBA SIMULATOR

27

BOILER FILLING

OBJECTIVE

• To line up to fill the water wall, down comers, drum & economiser by

boiler feed pump.

PRE - REQUISITES & STATE OF PLANT 1. Boiler water circulating pumps motor cavity is properly filled and vented.

2. Sufficient quantity of DM water available in condensate storage tank.

3. Hot well make-up pump available for chemical mixing and diluting.

4. Local drum gauge glass charged. Hydrastep and drum level recorder available

in UCB.

5. Unit ECW system in service.

6. At least one CEP is available to make up the deaerator level.

7. Hot well make-up system lined up from hot well make-up pump.

8. DC seal water pump for BFP is available. 9. MD BFP with all its auxiliaries/controls is available. 10. Instrument air supply to the entire controller is available. 11. Sufficient quantity of Ammonia and Hydrazine put in mixing tank and diluted

with DM water.

PRE - START CHECKS AND LINE UP 1. Close boiler low point drain valve to IBD tank. Close economiser inlet

2. Header drain and inlet lead drain valves at low point drain station.

3. Ensure that emergency blow down regulating valves is closed from UCB. 4. Ensure that all the three SGCW pump casing drains are closed. 5. Check SH and RH fill valve at low point drain station are closed. 6. Open all three SGCW pump suction spool vent valves from local. 7. Open all the drain vent valves from UCB.

*Line up for initial boiler filling over. *

KORBA SIMULATOR

28

DRUM FILLING SGCW PUMPS OBJECTIVE • To fill the boiler water wall, downcomers, drum and economiser by boiler

feed pump. • To line up and start SGCW Pump A & B PRE - REQUISITES & STATE OF PLANT 1. Check that condensate pump discharge header pressure is OK. 2. Equipment cooling water pumps are running. PRE - START CHECKS AND LINE UP 1. Open the economiser inlet valve E-2 and Economiser recirculation valves from the UCB. 2. Open the low range feed control station isolating valves, close high range isolating and control valves. Check low range control valve operation. 3. Check HP heaters feed water bypass valve full open (FW - 14). 4. Ensure MD BFP/ TD BFP is running 5. Start LP dosing pump to dose hydrazine and ammonia solution to BFP

suction.

OPERATIONAL STEPS 1. Gradually open the low range feed control valve and control the flow to boiler as

per rate of make up to deaerator.

2. Close the recirculation valve of the BFP if sufficient feed flow is established. 3. Close the SGCW pump suction spool vents once air free water comes out of them.

4. Check for level rise in local gauge glass, hydrastep and recorders.

KORBA SIMULATOR

29

5. Close the low range feed control valve and open the recirculation valve once the

level comes to about 300 mm.

6. Stop chemical dosing pump and isolate the dosing line. 7. Ensure the pump discharge valve are fully open, permissive lamp 1 and 2 are

ON.

8. Rack in the breakers of all the three pumps from SWGR. 9. Ensure the pump cooling water system is lined up from local . 10. Ensure the status of SG booster pump A as lined up . 11. Start the SGCW pump -A by turning the hand switch to close position. 12. Ensure the pump draws about 60 amps if current drawn is less stop the pump immediately and vent thoroughly 13. Check that drum level is adequate, if not open the low range feed control valve

to make it up.

14. Repeat the procedure for SGCW pump B also.

15. Check the following ;

a) Motor current

b) Motor cavity temp

c) Pump diff. press. and pump running condition OK at local

KORBA SIMULATOR

30

KORBA SIMULATOR

31

KORBA SIMULATOR

32

START UP AND WARM UP OF THE FUEL OIL SYSTEM. HEAVY FUEL OIL SYSTEM OBJECTIVE • To line up and start heavy fuel oil pump. • To warm up the fuel oil to required temperature for boiler light up. PRE - REQUISITES & STATE OF PLANT

1. Adequate oil level in the HFO storage tank for pump operation.

2. Auxiliary steam header charged and steam is available.

3. Local pressure, temperature, flow, level gauges and transmitters charged.

4. Duplex strainer of the HFO pump is in clean condition.

5. Work permit on the associated equipment cancelled.

6. The oil in the day tank is pre-warmed.

7. Day tank level (indicator at local) checked for proper working.

8. Ensure that instrument air supply is available. PRE - START CHECKS AND LINE UP

1. Open the suction valve and discharge valve of any one pump. 2. Charge the steam tracing system and heat sufficiently before the pump is taken in service. 3. Vent the pump thoroughly and close the vent valve. 4. Ensure the recirculation valve is open with its isolating valves. 5. Since the discharge line is empty crack open the oil valve inlet to the heater,

out let may be opened fully. 6. Ensure that H.O. short recirculation valve HO27is closed and operative from

KORBA SIMULATOR

33

UCB 7. Ensure that H.O. delivery valve (HO18) and inlet to the firing floor (HO25)

valves

are fully open.

8. Open the riser vent at GH elevation (HO44) initially. 9. Ensure that constant circulation orifice is lined up (by pass of HO long

recirculation valve).

OPERATIONAL STEPS 1. Start one HFO pump from local. 2. Check the pressure of fuel oil at the boiler front starts increasing gradually as

indicated.

3. Once the header is pressurised open the inlet valve to the heater fully. 4. Open the vent of the HFO heater before charging the steam. 5. Crack open the HFO heating steam by pass valve. 6. Close the drain and vent once the heater is thoroughly vented. 7. Open the short recirculation valve HO27 from UCB. 8. Take the temperature controller of the HFO heater in service to maintain the fuel

oil temperature to about 125 0 C.

* HFO pump in service *

KORBA SIMULATOR

34

KORBA SIMULATOR

35

KORBA SIMULATOR

36

KORBA SIMULATOR

37

LINE UP OF FLUE GAS PATH & APHs OBJECTIVE • To line up the flue gas path for boiler light up. • To line up and take secondary RAPH in service. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various boiler areas such as furnace, APH, ID, fans, ESP, ducts,

dampers, etc., cancelled and men, material removed from these areas.

2. Instrument air charged in boiler side pneumatic valves & dampers. 3. Unit equipment cooling system in running condition with SG side charged. 4. APH fire sensing device available. 5. Fire fighting water available for boiler and APHs. 6. APH soot blowing system available. 7. All the wall blowers and LRSB are in retracted condition. 8. Bottom ash equipment such as scrapper conveyer, clinker-grinder, hydraulic

oil Pumps, blowers, etc, available for taking into service.

9. Boiler slag bath, trough seal, economiser hopper, APH hoppers & ESP flushing Apparatus are filled with water and over flowing. HP-LP & service water pump

in Service (ASH).

10. Local pressure, temperature, flow, level gauges and transmitters charged. 11. Check all peepholes and manholes are closed. PRE - START CHECKS AND LINE UP 1. Check oil level in guide bearing and support bearing by dip stick and if

necessary top up with the correct oil to bring the level normal.

2. Establish ECW supply through guide bearing oil coolers. 3. Open the suction valve of the lub oil pump for APHs.

KORBA SIMULATOR

38

4. Open the inlet/outlet dampers for all the four ESP pass from GD11 to GD 18.

5. Open the equaliser dampers GD9 and GD10 before ESP from local . 6. Ensure that flue gas inlet damper and outlet damper to secondary RAPH A,

GD 3 and GD 7 are closed.

7. Ensure that secondary air inlet and out let dampers SAD3 & SAD5 for

secondary RAPH A are closed.

8. Ensure that primary RAPH A gas inlet/outlet dampers GD1 & GD 2 and GD5, GD6 are fully closed. 9. Ensure that all the dampers for secondary RAPH B are closed. 10. Line up the boiler bottom ash hopper system from local . 11. Switch on any of the three ash slurry pump from local . OPERATIONAL STEPS 1. Turn the secondary RAPH - A LOP A for guide bearing to lead mode. 2. Turn the secondary RAPH -A LOP B for guide bearing to lag mode. 3. Repeat the above two steps for the support bearing LOPs also 4. Repeat the above three steps for the secondary RAPH-B also 5. Check the permissive for secondary RAPH - a are all available 6. Line up air motor and start RAPH-A on air motor and ensure smooth running

of RAPH from local .

7. With the same sequence take secondary RAPH -B also in service on air motor. 8. Establish 415V supply and start RAPH electric motor by turning the hand

switch to close position.

9. Ensure that air motor cuts out on interlock. 10. Open the secondary air out let damper SAD5 followed by the inlet damper SAD 11. Open the flue gas out let damper GD7 followed by the inlet damper GD3.

* RAPH in service *

KORBA SIMULATOR

39

START UP AND LINE UP OF ONE ID FAN OBJECTIVE • To line up and start ID fan for boiler light up. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various boiler areas such as furnace, APH, ID, FD fans, ESP, ducts, damper, etc., cancelled and men material removed from these areas. 2. Ensure the flue gas path is lined up . 3. Atleast one secondary air-preheater is running. 4. HP/LP ash water pumps are running. 5. Boiler slag bath trough seal, economiser hopper, air preheater hoppers and

ESP flushing apparatus are filled with water and over flowing .

6. Instrument air is charged to various actuators and dampers, etc. 7. Boiler man holes, peep holes are in closed condition cooling water charged in access doors through SG booster pumps . PRE - START CHECKS AND LINE UP 1. Check that adequate oil level is in the tank, if necessary top up with the correct oil to bring the level to normal. 2. Charge the hydraulic coupling cooler and one lub oil cooler with Equipment Cooling Water. 3. Open the suction and discharge valve for the lub oil pump. 4. Ensure the line up of lub oil through cooler and filter upto the bearing from

local.

5. Ensure that inlet vane position controller is minimum and operative. 6. Rack in the 6.6 KV motor breaker for ID fan A from switch gear. 7. Keep the selector of ID fan oil pump in lead mode. 8. Ensure that hydraulic scoop position is minimum and permissive lamp is on.

KORBA SIMULATOR

40

OPERATIONAL STEPS 1. Give ID fan A breaker a start command and check the hydraulic oil pump A

takes start, red lamp comes on.

2. Ensure that inlet/Outlet dampers starts closing on interlock green lamp comes

on.

3. Hydraulic coupling oil pressure adequate permissive lamp comes on. 4. The moment inlet/outlet dampers get fully closed the fan will take start. Check

the starting and no load current.

5. Check that inlet/outlet dampers for the ID fan A opens after a time delay and

inlet/outlet dampers for the other fans close on interlock GD 20,21 and GD23

to GD 25

6. Check the bearing temperature and vibration from the UCB and are normal.

Also motor winding temperature is normal.

7. The hydraulic oil pump for the non running fans may be put in service after

line up.

8. Increase the inlet vane position to load the fan by raising the controller.

*ID fan taken in service*

KORBA SIMULATOR

41

FLU

E G

AS S

YST

EM

KORBA SIMULATOR

42

START UP AND LINE UP OF ONE FD FAN OBJECTIVE • To line up and start FD fan for boiler light up. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various boiler areas such as furnace, APH, ID, FD fans,

SCAPHS, wind box, burner tilts, etc., cancelled and men, material removed

from these areas.

2. Atleast one secondary air preheater is running. 3. The ID fan is running normal. 4. Instrument air is charged to all the secondary air damper actuators. 5. Secondary air damper control (SADC) checked for remote operation. 6. Wind box manholes are closed. 7. Unit equipment cooling system is in running condition. PRE - START CHECKS AND LINE UP 1. Check that adequate oil level is in the tank, if necessary top up with correct oil

to bring the level to normal.

2. Establish the ECW supply through fan lub oil coolers from local. 3. Ensure the line up of the lub oil through cooler and filter upto the bearing. 4. Ensure that blade pitch controller is minimum and operative. 5. Rack in the 6.6 KV motor breaker for FD fan A from Sw.GR. 6. Start the lub oil pump B in auto mode once lub oil pressure is adequate. 7. Keep the lub oil pump B in auto mode once lub oil pressure is adequate. 8. Interlocks of LOPs motor start/stop to be checked by tripping the running LOP.

KORBA SIMULATOR

43

OPERATIONAL STEPS

1. Give FD fan a start command

2. Ensure that outlet damper SAD - 1 starts closing and permissive lamp comes

on.

3. All the permissive will be available the moment discharge damper is closed the

fan will take start. Check its starting and no load current and also the motor

winding temperature.

4. Check that outlet damper for FD fan A reopens after a time delay and discharge

damper for FD fan B Closes on inter lock.

5. Check the bearing temperatures and vibrations from the UCB are normal. 6. Start the lub oil pump for the FD fan B. 7. Check the FD fan discharge pressure and wind box pressure should show

same value.

8. Increase the blade pitch of FD fan A to load the fan and observe that air flow

should increase.

9. Open the scanner air fan inlet dampers SID - 1/2 from local.

* FD fan in service *

KORBA SIMULATOR

44

KORBA SIMULATOR

45

LINE UP, CHARGING AND TAKING SCAPHS INTO SERVICE OBJECTIVE • To charge the SCAPHs from steam side. PRE - REQUISITES & STATE OF PLANT 1. The secondary air supply through the SCAPH is established. 2. Ensure 16 ata steam header is charged . 3. Ensure that drain valve down stream of SCAPH line supply header is open. 4. Ensure that final condensate outlet valve to IBD is open. 5. The instrument air is charged to all the pneumatic actuator. PRE - START CHECKS AND LINE UP 1. Open all the four inlet and outlet valves for Secondary air SCAPHs. 2. Ensure that secondary RAPH - A/B cold end temperature controllers are in

closed condition in UCB

3. Ensure the power supply is available to the motorised SCAPH valves. OPERATIONAL STEPS 1. Open the Secondary SCAPH A/B steam inlet valve from local. 2. Open the motorised valves upstream and downstream of SCAPH control valve 3. Crack open the Secondary air cold end temperature controller to warm up all

the lines.

4. Throttle drain valves when steam comes out of them. 5. After sufficient warm up, control valve can be opened more to achieve the

required cold end temperature.

6. Close all the drain valves downstream of the SCAPH 7. If required, adjust the temperature setter of the cold end temperature controller

and transfer the controller in auto mode.

* SCAPHS ARE CHARGED *

KORBA SIMULATOR

46

LINE UP FOR BOILER LIGHT UP

OBJECTIVE

• To line up all the associated equipment for boiler light up. PRE - REQUISITES & STATE OF PLANT

1. Work permit on various boiler areas such as furnace, APH, ID, FD fans, ESP,

ducts, damper, etc., cancelled and men, material removed from these areas.

2. Instrument air charged in boiler side for pneumatic valves and damper

operation, oil guns, etc.

3. Service air charged in boiler side for air heater, air motor ignitor cooling air, etc. 4. Ensure 16 ata steam header is charged 5. 6.6 KV switchgear charged . 6. 415 V supply available for LT drives and valve, damper actuators. 7. Unit equipment cooling system is in running condition. 8. Local pressure temperature, flow, level gauges and transmitters charged. 9. Oil guns and Ignitors checked to be proper fitted. 10. Secondary air damper control system (SADC) checked for remote operation. 11. Boiler manholes, peep holes are in closed condition. cooling water charged in

access doors.

12. DC/AC scanner air fan should be in service and interlocks should be checked. 13. All the wall blowers and LRSB are in retracted condition. 14. Boiler spring loaded safety valve gags are in removed condition (if light up is

being done after safety valve floating activity).

15. Bottom ash equipment such as scrapper conveyer, clinker grinder, hydraulic

oil pump, blowers, etc. available for taking into service.

KORBA SIMULATOR

47

16. Boiler slag bath, trough seal, economiser hopper, APH hoppers and ESP

hoppers, flushing apparatus are filled with water and overflowing.

17. Following boiler side equipment’s are available for taking in service with their

interlocks and protections checked.

• At least two numbers of CC pumps.

• Both Sec. APHs.

• AC scanner air fan.

• Atleast one ID fan.

• Atleast one FD fan.

• Both sec. APH SCAPHs.

18. Following equipment should also be made ready for requirements at later stage.

• Atleast one PA fan and one seal air fan.

• 3-4 nos. of coal mills and feeders.

• Both primary air preheater’s SCAPHs.

• ESP Transfirmers,ESP rectifier transformers,rapping motors, hopprr heaters etc.

19. Ensure that boiler drum filling is carried out . 20. Ensure S/H spray and R/H spray station block valves and control valves are

closed.

21. Open the S/H drain header drain valve to IBD full. PRE - START CHECKS AND LINE UP 1. Boiler drains and vents should be lined up as follows.

• Low point drain station to IBD isolating valves is closed.

• Bottom ring header drain valve at low point header is closed.

• Economiser inlet lead drain valve at low point header is closed.

• Emergency blow down valves B-127, B128 are operable and are closed.

2. Ensure both the economiser recirculation valves are open. 3. Open HP dosing isolating valve at drum level.

KORBA SIMULATOR

48

4. Open S-H steam, saturated steam, CBD water and feed water sampling

isolating valves.

5. Open all S/H header drains full for draining any where in S/H and leave them

crack open.

6. Open the S/H header vents manual valve fully. 7. Open the motorised boiler drum vent valves from section. 8. Open all four SH header vent valve 9. Ensure that main steam stop valve (boiler side)is closed along with bypass valves. 10. Open the motorised RH outlet header vent 11. Ensure sufficient cold end temperature of the Sec. RAPHs before light up. 12. Change the status of local oil gun station from local to remote for all four

corners and all four elevations.

13. Line up the boiler CBD lines from local . 14. Ensure that heavy oil pumps are running and warmed up. 15. Check that atomising steam is charged upto the firing floor. Also all the steam

tracing lines should be charged.

* Boiler lined up for light up *

KORBA SIMULATOR

49

BOILER LIGHT UP

OIL FIRING SYSTEM OBJECTIVE

• To start a purge cycle. • To light up the boiler. PRE - START CHECKS AND LINE UP

1. All the pre-start checks and line up mentioned earlier . 2. Ensure that all the operational steps mentioned before are carried out before

the boiler is ready for a purge cycle.

OPERATIONAL STEPS 1. Adjust the ID fan and FD fan blade pitch to maintain air flow above 30 % but

below 40 %.

2. Adjust the burner tilt position to horizontal with burner tilt controller 3. Keep the furnace pressure to about -10 mmwcl with ID inlet valve control. 4. Ensure that following purge permissives are satisfied :

• Mode permit (Nozzle tilt horizontal and air flow less than 40 %).

• PA fans off.

• Drum level satisfactory.

• Air flow > 30%

• All feeders off.

• All nozzle valves closed

• Wind box/furnace DP satisfactory.

• No boiler trip command.

• Aux. air dampers modulating.

• All hot air gates closed.

• All scanners sensing no flame.

• All pulverisers off.

KORBA SIMULATOR

50

• H.O. Trip valve closed.

5. If wind box/furnace DP permissive is not available wait for all the fuel air

dampers to close from top, once air flow is between 30 to 40 % pre-purge

damper reset timer will take 5 min.

6. Ensure that ‘PURGE READY’ & ‘PURGE START’ lamps are glowing at FSSS panel. 7. Push “Purge start” push button and see ‘purging ‘ lamp comes on the panel.

After purging time of 5 min. is over see purge complete lamp glows.

8. Ensure that master fuel trip relays MFR A and MFR B relay reset and green

lamp comes on.

9. Open H.O. trip valve. Valve opens, if not, open the long recirculation valve and

then open the H.O. trip valve.

10. Increase the H.F.O. pressure controller output. 11. Adjust the set point of the controller to about 10 - 12 Kg/cm2 and transfer the

controller to auto mode.

12. Wait till HFO temperature at boiler front comes to about 110 o C. 13. In between once again ensure that superheater vents etc. are fully open and

also drains are opened.

14. Close on oil recirculation valve, green lamp comes on and HFO supply pressure

momentarily increases

15. Insert the furnace probe LHS/RHS till it advances to about 80 to 100 %. Push

park button

16. Depress the ‘Pair 1-3 START’ push button on AB elevation. corner No. 1 is

placed in service initially and following occures.

• AB-1 oil gun advances.

• The spark rod advance yellow lamp comes on.

• The spark rod lamp comes for 15 sec.

• Heavy fuel oil nozzle valve start opening.

• Discriminating scanners starts sensing the flame.

• HEA ignitor spark signal is removed HEA ignitor is retracted

• Heavy oil nozzle valve open fully red open lamp comes on

KORBA SIMULATOR

51

• AB-3 gun will advance after 30 sec delay and same seq. as above will follow

17. Depress the pair 2-4 START push button on AB elevation. AB-2 is placed in

service similarly to AB-3 mentioned above.

18. The furnace pressure goes up slightly, increase the ID fan loading to maintain

the value to about -10 mmwc.

19. Increase the heavy oil controller output to maintain the H.O. supply pressure

to about 10 Kg/cm2. (Increase the set point if controller is in auto).

20. HFO temperature may drop as number of guns in service are more. Check the

HFO temperature is kept on auto mode at pump house.

21. Check the 16 ata header pressure is also maintained. 22. Adjust the CBD opening as per the chemist recommendations. 23. Maintain the drum level with low range feed control valve. 24. Maintain rate of rise of drum metal temp. less than 2 degree per minute and

that of main steam temp. less than 50C by controlling oil firing.

25. At drum pressure of 2 Kg/ cm2 close the boiler drum vents 26. Close all the superheater header manual vents and drains once pressure

exceeds 2 Kg/cm2 Perform APH soot blowing to avoid deposition of oil

unburnts.

27. Ensure that S.H. header vents (start up vents) are full open. 28. Check the furnace temperature by the furnace probes should not exceed 5400C. 29. Open emergency blow down valves if drum level is swelling to higher level. 30. Check the drum top bottom metal temperatures should not exceed 50oC.

** Boiler lighted up **

KORBA SIMULATOR

52

CONDENSER CHARGING OBJECTIVE

• To line up and start CW pumps. • To charge condenser from water side. PRE-REQUISITES & STATE OF PLANT

1. Work permit on various condenser/circulating water equipment’s such as

travelling water screen, circulating water pumps, ducts, condenser water box,

seal pit, etc., cancelled and men, material removed from these areas.

2. Adequate water level in the CW intake canal. 3. Electrical power available for circulating water pumps and associated

auxiliaries.

4. One condensate pump is running on recirculation . 5. CW priming pump is available. 6. Check that travelling water screen is clear and cleaning system is available for

operation.

PRE - START CHECKS AND LINE UP 1. Open the CW duct vents. 2. Close the condenser water box drains . 3. Establish the 415 V supply to the condenser inlet valves. 4. Ensure that discharge valves for all the three pumps are in closed position. OPERATIONAL STEPS 1. Start any one of the CW pump. 2. Line up the CW priming pump. 3. Open the CW inlet valve at condenser A and B. 4. After the system is filled up gradually open the condenser inlet valve to ensure

complete priming of the condenser water box.

KORBA SIMULATOR

53

5. Close duct outlet vents when water flows continuously from the vents. 6. Start the condenser water box priming pump 7. Line up and start the second CW pump and open the condenser inlet valve to

maintain the condenser water box pressure within limits .

8. After sometime switch off the condenser water box priming pump. 9. Close the CW duct vents also.

* Condenser charged *

KORBA SIMULATOR

54

CO

ND

EN

SE

R C

OO

LIN

G W

AT

ER

SY

ST

EM

KORBA SIMULATOR

55

LINE UP AND CHARGING OF TURBINE LUB OIL/SEAL OIL SYSTEM

LUB OIL / SEAL OIL SYSTEM OBJECTIVE

• To line up the turbine lub oil system.

• To start the generator seal oil system.

PRE - REQUISITES & STATE OF PLANT 1. Work permit on various turbine lubricating equipment’s such centrifuge

system, main oil tank, turbine lub oil coolers, vapour extractors, injectors,

main oil pump and associated pipe line thrust bearing filter etc., cancelled

and men, material removed.

2. Equipment cooling water pumps are running. 3. Instrument air is charged to various actuators. 4. Local pressure, temperature, flow, level gauges and transmitters charged. 5. Control power to turbine side instruments in UCB available. 6. 415 V power to various TG MCC ,TVDCcharged. 7. Adequate oil in the main oil tank is available. 8. The centrifuge and other oil purifier system is available. 9. Both the oil vapour extractors are available. PRE - START CHECKS AND LINE UP 1. Check that gate valve gearing closed with its SLC off. 2. Line up the lub oil cooler as per the standard practice (thorough venting of

cooler should be carried out).

3. Line up the thrust bearing lub oil filter and that ensure standby filter is available. 4. Open the oil temperature controller manually to about 30 %.

KORBA SIMULATOR

56

5. Check the lub oil supply valves to turbine and generator bearings are open.

These valves are normally adjusted at the time of commissioning.

6. Line up the seal oil cooling system from local . OPERATIONAL STEPS 1. Turn on the oil vapour extractor by pressing from UCB. 2. Start the generator bearing chamber exhaust fan 1from local. 3. Start one auxiliary oil pump from the insert 4. Check the lub oil pressure and AOP current are normal. 5. Switch on the SLC for the AOP2 and EOP from the control insert 6. Check the auto start of AOP2/EOP by switching off the AOP1. 7. Ensure that AOP 1 is running with its SLC on. 8. Transfer the lub oil temperature controller to auto mode 9. Line up and take in service seal oil coolers and oil filters . 10. Line up and start seal oil pumps 11. Ensure that air is purged out & generator is filled with CO2 12. Open the hydrogen supply valve to generator from local 13. Check the hydrogen pressure once the pressure reaches 4 Kg/cm2 then close

the valve.

14. Check the hydrogen purity from indicator in UCB and, get the measurement of

moisture in H2 is done

15. Check that seal oil tank levels are normal.

* Hydrogen filling done, seal oil pumps are in service *

KORBA SIMULATOR

57

KORBA SIMULATOR

58

KORBA SIMULATOR

59

TO TAKE HYDRAULIC BARRING GEAR IN SERVICE

JACKING OIL SYSTEM/TURNING GEAR

OBJECTIVE • To line up and start the jacking oil pump. • To keep the turbine on turning gear. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various turbine oil system as main oil tank turbine lub oil

coolers, vapour extractors, pressurising valves, etc., cancelled and men,

material removed from the area.

2. Local pressure, temperature, flow, level gauges and transmitters charged. 3. Turbine lub oil system charged. PRE - START CHECKS AND LINE UP 1. Check the fine control valve supplying high pressure jacking oil for open. 2. Check that pressure relief valve is properly set and the bypass valve is closed. 3. Ensure that turbine lub oil temperature controller is kept on auto. 4. Ensure the turbine differential expansions are within limits. OPERATIONAL STEPS 1. Start jacking oil pump. Check that jacking oil press. is normal. 2. Standby and DC jacking oil pumps available for service. Check winding

temperature locally.

3. Transfer the SLC mode of all the jacking oil pumps to auto. 4. Check the jacking oil pressure comes to about 125 Kg/cm2 5. Turn on the SLC turning gear. The gate valve gearing starts opening and

turbine speed goes up.

KORBA SIMULATOR

60

6. The speed should come up to approximately 80 RPM without vacuum, check

the lub oil temperature controller maintains the set lub oil temperature.

7. Check that bearing vibrations and bearing temperature are normal and lub oil

flow should be normal.

*Turbine on turning gear *

KORBA SIMULATOR

61

KORBA SIMULATOR

62

LINE UP AND START UP OF CONTROL FLUID PUMPS OBJECTIVE • To lineup and start control fluid pumps. • To charge the 8bar and 32 bar fluid to control system. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various turbine control oil system such as control fluid tank,

governing rack, coolers, accumulator, LP bypass valve’s actuators, pumps and

various interconnecting pipe - lines.

2. Control fluid tank level is adequate. 3. All the drains in the system are closed. 4. Local pressure, temperature, flow level gauges and transmitters charged. PRE - START CHECKS AND LINE UP 1. Check the line up of the duplex filters provided in the high pressure and low

pressure control system.

2. Charge the control fluid oil coolers from water side. 3. Open high pressure accumulator isolating valves provided at various high

pressure service points.

OPERATIONAL STEPS 1. Start any one of the control fluid tank vapour extractor. 2. Start control fluid pump, and check the discharge pressure and motor amps. 3. Keep the SLC of both the pumps to auto mode from console. 4. Establish control fluid supply to various services.

• Control fluid pump in service *

KORBA SIMULATOR

63

CONTROL FLUID SYSTEM WITH REGENERATION PLANT

1. Control Fluid Tank

2. Control Fluid Pump 32/8 Bar

3. Safety Valve

4. Circulating Pump

5. Shut-Off Valve

6. Fuller’s Earth Filter

7. Strainer

a. Control Fluid Approx. 8 Bar

a1. Control Fluid Approx. 32 Bar

C. Return Flow

C1. Riser Room Drainage

C2. Main Room Drainage

KORBA SIMULATOR

64

VACUUM PULLING OBJECTIVE • To line up the condenser circulating water system. • To line up and start the vacuum pump for establishing the vacuum. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various equipment such as condenser water box ,valves,

vacuum pumps, flash tanks, hot well, etc., cancelled and men, material

removed from the area.

2. Ensure condenser water box is charged. 3. Ensure Equipment cooling water is charged. 4. One condensate pump is running. 5. Turbine lub oil system is in service and turbine on barring gear. 6. The auxiliary steam header is charged. 7. All the possible air paths are blocked, i.e., turbine glands, hot reheat vents and

drains vacuum breaker valve, atmospheric lines coming to auxiliary flash box.

PRE - START CHECKS AND LINE UP 1. Close drains and fill the air/water separator tank of ELMO vacuum pump. 2. Line up tank level controller by opening isolating valve. 3. Vacuum pump A/B system lined up from local. 4. Charge, vent and take into service the condensate cooler. OPERATIONAL STEPS 1. Open air isolating valve, bypass valve and close the air ejector valve to put the

pump in hogging mode.

2. Open the drain valve of the gland steam supply from console 3. Open the aux steam block valve ASH-006 to to gland seal system. 4. Increase the opening of the steam seal supply valve to warm-up the header and

watch the gland steam temp.

KORBA SIMULATOR

65

5. Switch on the seal steam condenser exhauster from insert 6. Slowly increase the output of the seal steam pressure controller to maintain

pressure of 0.01 Kg/cm2.

7. Close the vacuum breaker 8. Pre-select the vacuum pump no. 1 from the selector switch 9. Open the vacuum pump air isolation valve no. 1. 10. Start the pump from the UCB console. 11. Check the vacuum builds up to about - 0.9 Kg/cm2 . 12. Close the air ejector 1 bypass valve and open the air ejector valve 1 to keep the

vacuum pump in hold mode.

13. Close the gland seal steam drain valve after gland steam temperature reaches

140 to 150 0 C

(Alternatively above steps can be done automatically if SGC evacuation is on Auto.)

* Condenser vacuum pulled *

KORBA SIMULATOR

66

VA

CU

UM

PU

MP F

LO

W D

IAG

RA

M

KORBA SIMULATOR

67

MAIN STEAM LINE WARMING AND CHARGING OBJECTIVE • To warm-up and charge the main steam line up to Emergency stop valves PRE - REQUISITES & STATE OF PLANT 1. Work permit on various boiler areas such as main steam stop valve, safety

valves, main steam strainer, various lines etc., cancelled and men, material are

removed from these areas.

2. Boiler is in lighted up condition and boiler drum pressure is about 6 to 8

Kg/cm2.

3. Condenser vacuum is pulled. 4. Boiler drum vents and superheater vents / drains are closed. PRE - START CHECKS AND LINE UP 1. Ensure that main steam header drain valve MSD-050 valve is open. 2. Open the main steam strainer drain valve MSD - 054 to MSD - 060 3. Open the hot reheat strainer drain valve MSD - 034 to MSD - 040 4. Check that SLC drain is kept on auto and drains are open as per the logic. OPERATIONAL STEPS 1. Turn the main steam stop valve’s MS-001 equaliser isolating valve to open position

and wait till it is fully open. Repeat the above step for MS - 002 valve also.

2. Crack open the regulating valve by holding the switch to open position for MS-

001 and MS - 002.

3. Wait for sometime; observe the main steam temperature rises before ESV. 4. Open further the bypass regulating valve to about 50 % and wait. 5. Open the main steam stop valve 1 and 2 after opening the bypass valve fully. 6. Check that bypass equaliser valves should close once the main steam stop

valves are full open.

* Main steam line warmed and charged. *

KORBA SIMULATOR

68

HP BYPASS CHARGING OBJECTIVE • To line up HP bypass system. • To take HP bypass into service. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various HP bypass oil unit, valves, desuperheater, lines, etc.,

cancelled and men, material removed from the area.

2. Oil level in HP bypass tank is normal. 3. Both HP bypass pumps auto start and stop with oil pressure < 110 Kg/cm2

and >160 Kg/cm2 checked OK.

4. All the five numbers hydraulic operated valves, i.e. BP1/2, BD, BPE1/2 oil line

valves are operative.

5. HP bypass control and instrumentation side checked and made available. 6. All the five numbers of hydraulic operated valves open and close operation

checked from local and control room in manual mode.

7. ECW system running and bypass valves BP1 and BP2 gland cooling water inlet

and outlet valves are in open condition.

8. Any one of the BFP is running and common feed discharge line is charged to

supply HP bypass spray water.

9. Turbine on barring gear, condenser vacuum pulled. 10. R/H start up vents electrical supply available. Also LP bypasses system lined

up and available to take care of RH steam flow and pressure.

11. Main steam line in charged condition with line drain open to flash tank - 6 and

HP strainer drain open to HP/LP Flash tank.

KORBA SIMULATOR

69

PRE - START CHECKS AND LINE UP 1. Open HP bypass flow nozzle down stream drain manual valves. 2. Close HP bypass spray water line manual drain valves after BD, BPE-1 and

BPE-2 valves.

3. Ensure that spray water line hydraulic valves BD, BPE1 and BPE2 are in fully

closed condition.

4. Open the HP bypass spray water line manual isolating valve. OPERATIONAL STEPS 1. Set the pressure setter of HP BP about 12 Kg/cm 2 from the console.

2. Adjust the temperature set point of BPE-1 and BPE-2 to about 220oC. 3. Adjust the LP bypass fixed set point to about 4 Kg/cm 2 and ensure that LP

bypass is kept on auto.

4. Ensure that the water spray pressure controller is in manual mode. 5. Open the BP1 and BP2 valve manually to about 5 % from the console. Check

that BD valves and both BPE valves get transferred to auto mode.

6. Check that HP Bypass down stream temperature increases, temperature will be

maintained by the spray valves BPE1/2 at about 220 0 C.

7. Raise the boiler firing by raising the heavy oil pressure to increase the steam

pressure.

8. Ensure that LP bypass has opened and hot reheat pressure is maintained as

per fixed set point.

9. Bypass valves can be put in auto mode with main steam pressure matching the

HP bypass pressure setter to have bumpless transfer after adequate boiler firing

is achieved.

10. Close the superheater header vents and start up vents. 11. The downstream temperature set point can be varied depending on the final

hot reheat temperature requirements during start up which is about 300oC.

(280oC to 340oC)

KORBA SIMULATOR

70

12. Close the reheater outlet header vents once the LP bypass valves are

sufficiently open to maintain minimum flow through reheater.

13. The HP bypass pressure setter should be gradually increased to about 40

Kg/cm2 to bring the main steam parameters for rolling the turbine.

Note 1 HP bypass valves will force close / not open under following condition. I) If the downstream temperature is more than 380oC. II) If vacuum is <0.8 Kg/Cm2 In case by pass valve closes fully, the corresponding spray valve should be closed

immediately to prevent water entry. The downstream temperature should be allowed to

come down naturally before opening the bypass valve again. The start up vents should

be opened to avoid stagnation of steam in superheater.

Note 2 Once unit is synchronised the main steam pressure and down stream temperature set

point of HP bypass system should be increased to more than operating full load

parameter but less than minimum MS safety valve setting. The valves can be 175

Kg/cm 2 and 340 o C. This is to be done to prevent unwanted opening of bypass and

spray water valves if controllers are kept in auto.

* HP bypass system taken in service *

KORBA SIMULATOR

71

HP B

YPA

SS S

YST

EM

KORBA SIMULATOR

72

LP BYPASS CHARGING OBJECTIVE • To line up LP bypass system • To take up LP bypass into service. PRE - REQUISITES & STATE OF PLANT 1. Work permit on various LP bypass valves, spray water valves, pipelines

condenser, etc., cancelled and men, material removed from these areas.

2. Control fluid pump is running, 32 bars and 8 bar control oil available. 3. Turbine lub oil and jacking oil system in service with turbine on barring gear. 4. Atleast one pass of condenser is charged with cooling water. 5. Atleast one condesate extraction pump is in service. 6. Condenser vacuum pumps in operation with condenser vacuum > - 0.6 Kg/cm2. 7. HP bypass lined up and available for service. 8. Boiler steaming with drum pressure about 6 to 8 Kg/cm2. PRE - START CHECKS AND LINE UP 1. Open the manual isolation valves for exhaust hood spray and drain manifold. 2. Open the LP bypass spray manual valve from local. 3. Injection water pressure switch, low vacuum protection switch in LP by pass

rack are in operating position.

4. Ensure that all the 8 bar control fluid line and various valves are open and

charged condition, e.g. main supply isolating valve to bypass rack, to

KORBA SIMULATOR

73

temperature dependent solenoid valves, injection water pressure switch,

etc.are open and in charged condition.

5. Check that individual injection water manual bypass valves are closed.

6. Check that isolating valves downstream of duplex filter in 32 bar control fluid

line for both LP BP control valves are open.

7. Check that drains, vents of both duplex filters are closed. 8. Check the main isolating valve in the injection water line from CEP discharge

header is open.

OPERATIONAL STEPS 1. Set the hot reheat pressure set point reference to 4 Kg/cm2 in LP bypass console. 2. Check that both temperature dependent solenoid valves are in reset condition

in LP bypass console, otherwise reset them.

3. Charge the main steam line and open the HP bypass valves upto 5 %. 4. With LP bypass valves in manual mode, give increase command to LP bypass

controller gradually till the injection water valves 1 and 3 opens full and then

both the bypass stop valves opens full as indicated in the console.

5. Increase the controller further till both the bypass control valves open about 25 %. 6. As HP and LP Bypass in service, the boiler start up vents, hot reheat vents can

be closed.

7. As HP Bypass valves open more (either in manual or auto), hot reheat pressure

will gradually approaches 12 Kg/cm2, raise the LP bypass fixed set point to 12

Kg/cm2.

KORBA SIMULATOR

74

8. Check the control error deviation in the console. When it becomes zero the LP

bypass controller can be switched to auto with automatic control interface (ACI)

off.

9. If LP Bypass downstream flow increases above 45 % , check that second set of

injection water valves open automatically and will be indicated on the console.

Note -1 LP bypass operation can be done with automatic interface kept ‘ON’. It will

automatically open the bypass control valve to 25 % and will hold it till the actual Hot

reheat pressure reaches 12 Kg/cm2. The ACI will be switched off.

Note – 2 Both the LP bypass stop and control valves will close if i) Condenser vacuum is less than -0.6 Kg/cm2.

ii) Injection water pressure after injection valves is less than set

value(18Kg/Cm2).

iii) Either of the stop and control valve will close if the corresponding

condenser wall temperature is more than 90 o C.

Note – 3 When turbine is on load, the LP bypass pressure set point (sliding set point) is a

function of HP turbine first stage pressure. The maximum of fixed and sliding set

point will be the operating set point and LP bypass will open if in auto mode, when

actual reheat pressure is more than this set point.

* LP bypass taken in service *

KORBA SIMULATOR

75

LP B

YPA

SS S

YST

EM

KORBA SIMULATOR

76

LINE UP FOR TURBINE ROLLING OBJECTIVE • To line up the turbine governing system and drains for rolling. • To line up and charge the stator water system. PRE - REQUISITES & STATE OF PLANT 1. Work permits on various turbine side equipments like main oil pump’

HP/IP/LP turbine, generator, extraction system, drains, reheat steam lines,

extraction NRVs, etc., are cancelled and men material removed from these

areas.

2. The turbine lub oil system and jacking oil system charged and turbine is on

barring gear.

3. Atleast one control fluid pump is in running condition and 32 bar and 8 bar

fluid charged to various parts of governing system.

4. The boiler is lit up condition with HP/LP bypass in operation and main steam

pressure/temperature to about 40 Kg /cm 2with 350 OC.

5. Adequate water level in the primary water tank and nitrogen charging system

available.

6. The control power supply to the governing panels/insert available.

PRE - START CHECKS AND LINE UP 1. Open the drain before HP control valve 1 to 4 to about 60 % in manual mode

from UCB console

2. Open the drain upstream and before seat of interceptor valve MSD-093 to MSD

096

3. Open the ESV seat drain MSD-091/92

4. Check that primary water line drains are closed. 5. Line up the primary water system by opening the suction and discharge vlv and

taking one cooler and one filter in service.

6. Open the stator water cooling system manual inlet isolating valve from local. 7. Ensure that generator lockout relay is reset from GRP panel.

KORBA SIMULATOR

77

1. Ensure that SLC drain is ON. 2. Check the TSE indicator and recorders are healthy and showing the correct

values.

3. Check the main steam pressure about 40 Kg/cm2 and temperature < 3500C

with hot reheat pressure about 12 Kg/cm 2 and temperature around 3600C.

OPERATIONAL STEPS 1. Start the primary cooling water pump from local . 2. Open the exciter cooler and hydrogen cooler isolating valves. 3. Check the primary water flow & temperature from the UCB. 4. Ensure that unit is on the limit pressure mode with deviation positive on

console.

5. Switch on the tracking device from the insert 6. Reduce the starting device to zero value. Check that trip oil pressure is built

and auxiliary start up oil pressure should come up to more than 5 Kg/cm2.

7. Ensure the TSE effect is ON. 8. GT / UAT cooler control system lined up . 9. Ensure that hydrogen temperature controller and primary water temperature

controller are healthy and are available.

10. Raise the speeder gear to 100 % position. 11. Adjust the load limiter to about 50 MW

KORBA SIMULATOR

78

TURBINE ROLLING SYNCHRONISATION OBJECTIVE • To roll and soak the turbine at rated speed. • To synchronise the machine and achieve the block load. PRE- REQUISITES & STATE OF PLANT 1. Work permit on various generator side equipments such as exciter, AVR, field

breaker, generator transformers, unit auxiliary transformers, etc., cancelled

and men, material are removed from these area.

2. The line up for the turbine rolling is done. 3. The switchyard 400 KV buses are charged with bus coupler close. 4. The main steam parameters are available and HP / LP bypass in service. 5. All the lockout relays in the generator protection panel are reset. 6. A minimum of three / four pulverisers are available to be taken into service. 7. Steam driven BFPs are also available. 8. Hydrogen pressure is adequate( 4.0 Kg/cm2 ) and spare bottles are available. PRE-START CHECKS AND LINE UP 1. Check the excitation not blocked, signal is available in the control panel. 2. Check that the load limit is greater than 50 MW. 3. Check that hot reheat and cold reheat drain valves are open 4. Ensure that main generator voltmeter selector is not in off position. 5. Check the operation of Gen. Transformer tap position selector. 6. Close the 400 KV generator - 6 bay’ main bus -2 line isolator (SEM - 6004) from

switch yard .

7. Ensure the Earthing switch ( SEM - 6008 ) is in open condition from switch

yard .

KORBA SIMULATOR

79

8. Close the 400 KV generator -6 bay’ breaker, incoming isolator (SEM-6006). 9. Ensure all other isolators are in open condition. 10. Line up the G.T. cooling water circuit from local . 11. Switch on the generator transformer control supply for all the three phases

from local Ensure that exciter air cooler isolating, hydrogen cooler isolating,

stator water coolers are charged

12. Switch on the control supply for both the unit auxiliary transformers by

changing the status

13. Ensure that GT/UAT cooler control system is in lined up condition 14. Ensure that speed reference set point is zero. 15. Ensure that turbine is kept on turbine follow mode with the minimum load

limited about 100 MW on the coordinated control system insert.

16. Ensure that trip oil pressure and start up oil pressure values are normal OPERATIONAL STEPS 1. Raise the starting device slowly to about 42 % . 2. Ensure that start up oil pressure has decreased and at about 42 % of the

starting device position the HP stop valves open.

3. Further raise the starting device position to open the hot reheat stop valves.

4. Checks the temperature of the turbine stop valves at 50 % depth and control

valve temperature at 50 % and 100 % depth from TSE recorders.

5. Keep the warm-up controllers in auto mode. The output of the controller will

modulate to maintain the TSE margin for stop valves.

6. Raise the starting device position to about 80 % and check that secondary oil

pressure has build to open the control valves.

7. Put the load gradient on from UCB console.

KORBA SIMULATOR

80

8. Ensure the pressure controller deviation is on positive side.

9. Ensure that drum level is on lower side to avoid sudden swing which may cause

water carry over.

10. Raise the speed reference to about 360 RPM from UCB.

11. Check the uniform opening of control valves and turbine acceleration rate. 12. Ensure that gate valve gearing has closed when turbine speed exceeds 240

RPM.

13. Check that ‘Jacking oil pump’ has switch off at speed of about 540 RPM 14. Check all the bearing temperature rise and bearing vibrations to be normal. 15. Check the thrust bearing temperature and the differential expansions. 16. Soak the turbine at the soaking speed till the HP shaft temperature at 50 %

depth (Calculated) reaches to about 1800C with respect to existing main steam

temperature as per the X curves.

17. Check the TSE margin for various channels. First it will reduce and then

gradually will increase once the difference between surface and mean

temperature reduces.

18. Raise the speed reference to 3000 RPM in one stroke. 19. The turbine speed starts increasing opening of IP control valves can be seen at

this stage.

20. At speed of about 2960 RPM the AOP should be switched off as main oil pump

takes over (ensure that SLC for all the oil pumps are on).

21. Soak the turbine at 3000 RPM till IP shaft mean temperature (50 % depth) with

respect hot reheat temperature as per the rolling X curves is satisfied.

22. Check that a minimum of about 30 K margin should be available before unit is

to be synchronised.

KORBA SIMULATOR

81

23. Close the generator field breaker from AVR console. 24. Raise the AVR set point to build the Generator voltage to about 21.5 KV 25. Match the auto and manual set point of the AVR and transfer the AVR to auto

mode.

26. Ensure that load controller is on with load gradient kept at 20 MW/min. 27. Turn on the synchroscope switch to check mode. All the meters showing

incoming and running voltage and frequency energises. The synchroscope rate

of rotation reflects the difference between incoming and running frequency.

28. Adjust the voltage so that incoming and running voltage values are same. 29. Adjust the turbine speed so that synchroscope is slowly rotating in clockwise

direction showing incoming frequency is slightly higher than grid.

30. Check the breaker closing permissive green lamp glows once synchroscope is

between 11 to 12 O’clock position.

31. Close the generator breaker when Gen. breaker closing permissive green lamp

comes. The synchroscope indicator locks at the 12 O’clock position. The

generator breaker closed red lamp comes on.

32. Immediately raise speed reference to pick up the load on the machine to avoid

reverse power trip or low forward power trip.

33. Increase the load as per the TSE margin and at the earliest close HP/LP bypass valves. 34. Ensure that warm-up controllers have closed, otherwise close them manually. 35. Close all the drains which were opened during rolling. 36. Turn off the synchroscope switch to de-energise the synchroscope. 37. Check that Prlim value slowly increase. Also ensure that load reference set

point is higher than the actual load value.

KORBA SIMULATOR

82

38. Observed that change over from speed controller to load controller takes place

once output of load controller is greater than that of speed controller. The load

controller active facia glows on the insert.

39. Raise the starting device position to 100 %. Check the increase in auxiliary

secondary oil pressure. Also ensure that tracking device is switched on.

40. Increase the load limiter value to about 150 MW from insert 41. Check the generator slot,core, exciter air and hydrogen cold gas temperatures 42. Check from the multipoint selector switches, generator stator core temperature. 43. Raise the HP bypass pressure set point to about 160 Kg/cm2 and temperature

set point to about 3400 C to avoid HP bypass opening on auto.

44. Ensure that LP bypass stop valves and spray valves have closed fully.

* Unit synchronised with load controller in service *

KORBA SIMULATOR

83

LP HEATER CHARGING

OBJECTIVE

• To line up LP heater from water side.

• To charge the LP heater from steam side.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on various LP heaters, drip valves, level gauges, water side valves,

NRVs, etc., cancelled and men, material removed from these areas.

2. The unit is synchronised and HP/LP bypass valves are closed.

3. The instrument air is charged to various drip valves and valves are checked for

the operation on auto.

4. All the pressure gauges, local level gauges, root valves and various instrument

impulses lines are charged or in service.

5. The 415 V power to various motorised valves are available.

PRE-START CHECKS AND LINE UP

1. Check that LPH-1condensate inlet/outlet valves are in open condition and

bypass valve is in closed condition.

2. Ensure all the shell side heater vents are in open condition represented

3. Check that all the isolating valves of the LP heater level controllers are full open

for all the three heaters.

4. Charge the local level gauges for all the three heaters.

OPERATIONAL STEPS

1. For LPH1 put the normal drain valve control switch to control mode from section.

The valve starts modulating to maintain the LP heater level.

2. Check that LPH-2 condensate inlet/outlet valves are in open condition and

bypass valve close.

KORBA SIMULATOR

84

3. Open the extraction steam isolating valve to LPH2.

4. De-energise the extraction NRV solenoid from ATRS console by pressing the left

side push button. The NRV position starts increasing as the steam goes to LPH2.

5. Put the normal drain valve control switch to control mode. The valve starts

modulating to maintain the LP heater level.

6. Check the condensate inlet / Outlet valves for the LPH3 are open and bypass

valve closed.

7. Open the extraction steam isolation valve to LPH3

8. Put the normal drain valve control switch to control mode. The valve starts

modulating to maintain the heater level.

9. De-energise the extraction NRV solenoid from ATRS console.

10. Check the condensate temperature after LPH-1,2,3. The temperature should

gradually increase(in DAS ).

11. Close the heater vents from local .

* LP heaters charged *

KORBA SIMULATOR

85

TO TAKE PULVERISER INTO SERVICE

OBJECTIVE

• To line up start primary air fans.

• To line up and start pulveriser.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on various pulveriser side equipment such as seal air fans and valves,

pulveriser discharge valves, cold air damper, hot air gate and dampers, feeder, coal

bunker mill reject system etc., cancelled and men, material are removed from these

areas.

2. The equipment cooling water system is charged and all the coolers are in charged

condition.

3. Atleast one set of ID fan and FD fan are running with furnace purging carried out.

4. FSSS start command to start the PA fan should be available.

5. Instrument air is charged to all cold and hot air damper actuators.

6. Primary air preheater is in service with air / gas dampers in open condition.

7. Auxiliary steam should be available for cold End temperature controllers.

8. Secondary air temperature should be adequate (about 2000 C).

PRE - START CHECKS AND LINE UP

1. Check that adequate oil level is Ok.

2. Take any one primary RAPH in service and ensure the dampers are open.

3. Establish the equipment cooling water supply through the lub oil coolers for PA

fan .

4. Line up the PA fan A lub oil circuit .

5. Rack in the 6.6 KV breaker for PA fan A.The green lamp in UCB glows.

KORBA SIMULATOR

86

6. Switch on the lub oil pump A for PA fan A and keep the selector switch of B in

lead mode. Check auto interlocks of the lub oil pumps.

7. Ensure that blade pitch is minimum and operative.

8. Ensure that the control / lub oil pressure is adequate.

9. Open the cooling water inlet valve to PA fan A and B .

10. Lub oil sump level for the pulveriser is normal.

11. The pulveriser discharge valves are open.

12. Open the cold air gate for all the pulverisers.

13. Ensure the tramp iron valve is open.

14. Start the lub oil pump for the pulveriser.

15. Check the lub oil pressure satisfactory permissive appears on the FSSS console.

16. Ensure that both the hot air damper and cold air dampers are operable from

UCB.

17. Ensure the feeder inlet gate is open and corresponding permissive lamp is

glowing in FSSS console.

OPERATIONAL STEPS

1. Take the primary RAPH A in service similar to the secondary RAPH.

2. Give PA fan A start command

3. Ensure that outlet damper PAD-1 starts closing.

4. All the permissive will be available the moment discharge damper is closed the

fan will take start. Check its starting and no load current.

5. Check that outlet damper for PA fan A reopens after a time delay and discharge

damper for PA fan B closes on interlock.

6. Check the bearing temperature and vibration from UCB are normal.

KORBA SIMULATOR

87

7. Ensure that lub oil pump for PA fan B is running with standby pump in lead

mode for both the fans.

8. Increase the blade pitch of PA fan A, and observe that PA fan A discharge

pressure increases.

9. Bring the PA header pressure to about 800 mmwcl by raising blade pitch

further.

10. Improve the cold end temperature by charging the SCAPH.

11. Ensure that 2 nos. of seal air fan are running, otherwise standby fan will get

start command from the FSSS console.

12. Open the pulveriser discharge valve by pressing the open push button.

13. Ensure that the pulveriser mode is in manual.

14. Check that ignition permit is available for the pulveriser to be taken into

service and all 4 oil guns are in service.

15. Ensure that the following pulveriser start permissives are satisfied.

• Start permit (nozzle tilts horizontal and air flow less than 40 %).

• Outlet temperature less than 93 0C.

• Coal feeder in remote.

• No auto unsuccessful start.

• Pulveriser lub oil pressure satisfactory.

• Tramp iron valve open.

• Ignition permit.

• Discharge valves open.

• Cold air gate open.

• Primary air permit.

• No pulveriser trip command.

KORBA SIMULATOR

88

• Feeder inlet gate open.

16. Momentarily press the pulveriser start push button. The following events will

occur.

• The pulveriser seal air valve opens and red open light comes

• Once seal air header to pulveriser under bowl differential pressure is more than

8 inch WCl, seal air pressure OK permissive comes

• All the permissive on the console appear and pulveriser ready lamp glows.

• Pulveriser ammeter pegs out to draw the starting current and comes down to no

load value.

• Pulveriser cold air damper opens 100 % and primary air flow to mill comes to 95

T/hr.

17. Maintain the furnace pressure by raising the ID fan inlet guide vanes.

18. Open the hot air gate by pressing the ‘Open ‘ push button. Hot air gate opens

and red open lamp comes on.

19. Open the hot air damper and simultaneously decrease the primary air flow

controller to maintain about 95 T/hr of primary air flow.

20. Check the pulveriser outlet temperature increases gradually since hot primary

air is going through the mill.

21. Start the feeder by depressing the start push button. The feeder starts and

coal flow rate comes to approximately 12 T/hr

22. Increase the loading on the mill by raising the feeder speed and maintain the

pulveriser outlet temperature to about 770 C.

23. Check the furnace pressure and maintain it to about - 15 mmwcl by loading

the ID fan.

24. Increase the opening of the fuel air damper as per the feeder speed.

KORBA SIMULATOR

89

Start the feeder B

25. Check that the fire ball scanners should start sensing flame and flame failure

protection gets armed corresponding red lamp comes on

26. Check the pulveriser bowl differential pressure and mill motor current and

raise the coal feeding accordingly.

27. The drum level and other parameters are to be maintained during this

operation.

28. Electro Static Precipitator can be put in service, when coal firing has stabilised

considerably in 3 to 4 mills.

* Pulveriser taken in service *

KORBA SIMULATOR

90

STEAM TEMPERATURE CONTROL

OBJECTIVE

• To line up and charge superheater attemperation system.

• To line up and charge reheater attemperation system.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on various attemperating side equipments such as block valve,

control valves, impulse pipeline, isolating valves and associated piping

cancelled and men, material are removed from these areas.

2. Minimum one BFP is running with feed water charged upto the feed control

station after HP heaters.

3. Instrument air is charged to all the control valve actuators.

4. Valve power is available to the SH attemperation/RH spray block valves.

5. The boiler load (steam flow) is more than 30 % with drum pressure around 80

Kg/cm2

PRE-START CHECKS AND LINE UP

1. Line up the SH attemperation circuit.

2. Line up RH attemperation circuit.

3. Check the trend of the main steam and reheat temperature rise during the load

raising operation.

OPERATIONAL STEPS

1. Open the SH attemperation isolation block valve S - 82.

2. Open the SH outlet temperature controller LHS isolating block valve S - 83.

The pressure equalising valve opens first and then main valve opens fully.

3. Open the SH outlet temperature controller RHS isolating block valve S - 86

similarly.

KORBA SIMULATOR

91

4. Increase the controller output to about 10 % manually. Check the valve

position indicator also goes 10 % open.

5. Check that superheater spray water flow increases on recorder.

6. Increase the controller output for the RHS also. Check the valve position

indicator also goes up.

7. Open the isolating block valve for the RH attemperation control R - 31

8. Open the isolating valves for each left and right hand side reheater

attemperation station R - 32 or R -33 and R - 34 or R - 35

9. Reduce the burner tilt first by the controller, if the HRH temperature is rising

rapidly.

10. Increase the RH spray on LHS and RHS to maintain the HRH outlet steam

temperature.

11. Check the temperature variation in the recorders, which is a positive indication

of spray flow.

12. Check that rate of increase of SH and RH temperature should slow down,

otherwise further raise the attemperation control valves to increase the flow

rate.

Note 1 To control RH temperature, first the burner tilts should be used. The

attemperation is to be used only in emergency condition.

* SH and RH attemperation is in service *

KORBA SIMULATOR

92

SUPERHEATER SPRAY CONTROL STATION

REHEATER SPRAY CONTROL STATION

KORBA SIMULATOR

93

CHARGING OF UNIT AUXILIARY TRANSFORMERS

OBJECTIVE

• To charge 6.6 KV unit bus through unit auxiliary transformers.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on both the unit auxiliary transformers, associated system

cancelled and men, material removed from the areas.

2. The unit is in synchronised condition with load more than 75 MW.

3. The unit auxiliary transformer cooler control system in lined up condition.

4. Ensure that 6.6 KV unit Swgr Normal incomer breaker from UAT is reset.

5. Ensure that UAT A / B control supply is on.

OPERATIONAL STEPS

1. Turn the 6.6 KV Unit Swgr No. A, UAT-A incomer Syn. hand switch to check

mode. The synchroscope indicator locks up at 12 O’ clock position and

voltages for incoming and running are shown.

2. Adjust the voltage of the incoming by changing the excitation set point from

AVR console to match the running station supply voltage

3. Check the breaker closing permissive green lamp glows as soon as the voltage

is matched (Keep the incoming slightly on higher side).

4. Close the 6.6 KV unit Swgr 6A, UAT-A incomer breaker. The breaker closes

and ammeter starts showing the current drawn.

5. Open the 6.6 KV tie breaker.

6. Switch off the synchroscope by turning it to off position.

7. Check the UAT A winding temperature & oil temperature.

8. Repeat the above procedure Sl.No. 1 to charge the Unit Auxiliary Transformer B

also.

9. Check the UAT- B winding temperature & oil temp..

** 6.6 KV buses charged from UATs **

KORBA SIMULATOR

94

LOAD RAISING OPERATION

OBJECTIVE

• To remove oil support once coal firing is established.

• To raise the unit load upto 50 %.

PRE - REQUISITES & STATE OF PLANT

1. The unit load is about 75 MW with Unit Auxiliary Transformers charged.

2. Three to four pulverisers are ready with all associated equipments.

3. The superheater and reheater attemperation is lined up.

4. Check that sufficient margin is available on TSE to raise the load.

5. Raise the load limit on both EHG and CCS consoles to about 300 MW.

OPERATIONAL STEPS

1. Checks that the upper load margin in the TSE indicator and IPS temperature

margin in TSE recorder are adequate to load the turbine further.

2. Take two more pulverisers in service as per the standard procedure mentioned

earlier.

3. Increase the loading on all the three pulverisers equally and check for better

combustion condition in the furnace.

4. If oil elevations at AB/CD/EF are in service, then oil guns at EF elevation can

be removed for economic operation.

5. Depress the PAIR 1-3 stop’ push button on’ oil console at EF elevation.

6. Check that the oil nozzle valve closes and associated ‘closed’ light comes on, spark

rod of ignitor advances and sparks for 15 secs then retracts back.

7. Ensure that oil gun at corner 1 and 3 retracts back once the 5 min scavenge

operation of oil gun is complete.

8. Repeat the same for the pair 2-4 also, check till both the oil guns retracts back.

9. Reduce the heavy oil pressure.

10. Increase the feeder speed for all the three feeders beyond 60 % and check the

flame intensity at AB as well as BC should improve

11. Raise the load reference on EHG control insert to pickup the load as the drum

pressure increases.

12. Maintain the SH and RH outlet temperatures by increasing the opening of the

attemperation control valves or reducing the burner tilts.

KORBA SIMULATOR

95

13. Change the set point of mill A outlet temperature and PA flow by turning the

knob till it comes to 770C and 95 T/ hr respectively.

14. Check the error deviation of the controllers to be zero and transfer the

controller in auto mode by pressing the middle A/M push button.

15. Repeat the above operation for other pulverisers, watch the outlet temperature

and bowl differential pressure.

16. Keep the bias setter for all the three pulverisers at 1 .

17. Raise the output of the fuel master till the error deviation in each feeder speed

comes to zero. (Adjust the bias setter if loading is unequal.)

18. Transfer all the feeders to auto mode and raise the fuel master output. All the

three feeders will get loaded simultaneously.

19. Keep on increasing the load set point as the parameters are building.

20. Maintain the air flow / furnace pressure / wind box pressure as the firing is

changing by adjusting the respective controls in UCB.

21. Check the loading of the auxiliaries as the load approaches 50 %

approximately.

* Unit load is brought to 50 % *

KORBA SIMULATOR

96

TAKING SECOND SET OF AUXILIARIES

OBJECTIVE

• To start the second set of auxiliaries.

• To keep various control loops on auto.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on the second set of auxiliaries second stream of flue gas /

secondary air and primary air ducts, etc., cancelled and men, material are

removed from these areas.

2. The unit load is about 50 % .Cold reheat pressure is more than 12 Kg / cm2 to

start TD BFP.

3. TD BFP and its associated auxiliary are normalised and a re available.

OPERATIONAL STEPS

1. Keep the selector switch of second condensate pump in normal mode.

2. Ensure the suction valve and recirculation valve of CEP- B are full open.

3. Start the condensate pump B and observe that motor current is normal.

4. Check the condensate pump discharge header pressure increases slightly.

5. Adjust the set point of the recirculation controller and transfer the controller to

auto mode.

6. Start the TD BFP A Auxiliary oil pump A .

7. Ensure that the BFPT-A Exhaust valve to condenser is open.

8. Open the suction valve, recirculation isolation valve.

9. Reduce the starting device to zero from BFPT governing console.

10. Select the EHTC mode from the insert.

11. Open the cold reheat steam to BFPT-A block valve Ex-20.

KORBA SIMULATOR

97

12. Raise the starting device position to about 60 % to open the stop valve and

further increase the speed of the BFP.

13. Raise the speed reference to increase the BFP discharge pressure. Check that

BFP suction flow also increases.

14. Stop the motor driven boiler feed pump once the TD BFP is taken in service.

15. Similarly line up and start the TD BFP B for load raising operation.

16. Line up and start the ID fanB and balance the loading of both the fans.

17. Line up and start the FD fan B and balance the loading of both the fans.

18. Increase theoutput of fuel flow control master manually to increase the firing.

19. Check that all the coal feeder loading has increased and pulveriser amps have

increased.

20. Adjust the output of the boiler master so that deviation on the fuel master and

FD Fan blade pitch comes to zero.

21. Transfer the FD controller in auto for a smooth change over and check that the

air flow doesn’t change drastically.

22. The boiler master can be used now to increase or decrease the load on the

boiler. The unit may be kept in Boiler Follow mode with limit pressure mode in

operation (after having kept first Fuel Master on Auto and then Boiler Master

on Auto).

23. Start PA fan B along with primary RAPH B.

24. Take pulveriser D in service and load the feeder. The coal flow in all three

pulveriser will reduce to compensate additional coal flow.

25. Increase the Boiler Master output slowly to raise the firing if Boiler Master is

kept manual.

KORBA SIMULATOR

98

26. The boiler temperature, pressure rapidly increases as a result of increased coal

firing.

27. Raise the load set point Pref. check that opening of the HP control valve

increases.

28. Increases the attemperation, if the rate of rise of SH and RH temperature

becomes very high.

29. Increase the maximum load limit set point on the CMC console as well on the

EHG panel to about 500 MW.

30. Adjust the furnace pressure set point to about -15 mmwcl and keep the bias

setter to about 1 and transfer the controllers to auto mode.

31. Remove the oil guns at CD elevation.

32. Check that both the PA fans are equally loaded. Raise the set point for PA

header pressure to about 800 mmwcl and set the bias setter to 1.0 by turning

the knob. Transfer both the controller to auto mode after ensuring the control

deviation is zero.

33. Repeat the above step for FD fans; note that FD set point is generated by the

Boiler Master.

* Second set of auxiliaries in service *

KORBA SIMULATOR

99

TD

BF

P S

YST

EM

KORBA SIMULATOR

100

LOAD RAISING OPERATION WITH CCS.

OBJECTIVE

• To line up and take HP heater in service.

• To raise the load to rated value.

PRE-REQUISITES & STATE OF PLANT

1. Work permit on the HP heaters, drains, control valves, associated piping, etc.,

cancelled and men, material are removed from these areas.

2. The unit load is around 50 % with both set of auxiliaries running.

3. The boiler pressure is around 100 Kg /cm2.

OPERATIONAL STEPS

1. Ensure that HPH both the streams are charged through water side i.e. HPH

inlet and outlet valves open with bypass valve closed.

2. Open the extraction steam to HPH 5 block valve EX-008

3. Open the extraction steam to heater 5A and 5B by opening EX-005 and EX-006

respectively.

4. De-energise the FC NRVs from ATRS console.

5. Turn the control switch of HP heater 5A and 5B drip to deaerator valve LCV-

0712, 034 to control position and release it.

6. Check that the heater levels are normal and controller modulates to maintain

level.

7. Close the Extraction steam line drain valve after NRV, MSD-063

8. Check that HPH 5A feed water outlet temperature increases.

9. Check that HPH 5B feed water outlet temperature increases.

10. In the same manner charge HPH 6A and 6B also. Check that drip control valve

LCV-0701 and LCV-0723 maintains the HP heater level.

KORBA SIMULATOR

101

11. HPH 6A and 6B outlet feed water temperature increases.

12. Take two more pulverisers in service (preferably E and F in continuation)

maintain their outlet temperature.

13. Transfer the feeder control of the above pulverisers to Auto.

14. Match the load demand signal to actual load by raising the unit master output

from coordinated control system console.

15. Ensure the load gradient to about 5 MW/min for better result.

16. Increase gradually the throttle pressure set point above the actual pressure

value by 2 to 3 Kg/cm2.

17. Transfer the boiler master to auto mode. Check the output of the boiler master

increases to maintain the set throttle pressure.

18. Ensure the minimum load and maximum load set point are 50 and 500 MW

respectively.

19. Place the unit in coordinated mode. The Unit control mode Coordinate facia

glows on the insert.

20. Raise the Unit Master set point to about 350 MW.

21. Watch all the unit critical parameters carefully and check that they are not

going beyond limit.

22. Check that the generator reactive power is within limits as per the generator

capability curve.

23. Raise the throttle pressure set point gradully and check that the boiler firing

rate also goes up.

24. Increase the Unit Master set point to 450 MW and check that sufficient upper

margin for load raising is available.

KORBA SIMULATOR

102

25. Check that steam flow, air flow, fuel flow increases as a result of higher load

set point as the unit is in Co-ordinated mode.

26. Adjust the set point of the Reheater and Main steam temperature set points to

540 o C and transfer the spray controllers to auto mode.

27. Watch the trend of main steam and reheat temperature, it may come down

since HP heaters are charged, however same shall be controlled as spray

controllers are in auto.

28. Check the unit load limiter on both console is beyond 500 MW. Raise the unit

master set point to 500 MW.

29. Check that the control valve opening increases, load comes to 500 MW.

* Load raised up to 500 MW *

KORBA SIMULATOR

103

KORBA SIMULATOR

104

KORBA SIMULATOR

105

KORBA SIMULATOR

106

CURVES FOR COLD START UP

Time Min.

Activity Main STM Press

KG/SQCM

Main STM

Temp. Deg. C

RH STM Press

KG/SQCM

RH STM

Temp. Deg. C

Turbine Speed RPM

Main STM Flow

T/HR.

Gen Load MW

000 Start Ignitors/ 00 ---- ---- ---- ---- ---- ----

Oil Guns

100 Open LP/HP Bypass 08 100-

140 ---- ---- ---- ---- ----

315 Start Rolling 54 350 12 340 ---- 00 ----

375 Syncronisation 54 350 12 340 3000 120 30

390 Close LP/HP

BP 54 350 12 340 3000 200 50

400 Cut In 1-st

Mill 60 350 15 340 3000 275 70

450 Cut In HP

Heaters 85 375 20 370 3000 700 175

460 Cut In 2-nd.

Mill 90 380 22 375 3000 740 190

480 Cut In 3-rd

Mill 110 405 26 400 3000 820 270

510 Cut In 4-th

Mill 125 430 30 425 3000 1020 320

550 Cut In 5-th

Mill 150 450 34 450 3000 1300 400

600 Cut In 6-th

Mill 170 475 40.5 475 3000 1600 500

And Reach Full

Load

660 Reach Rated

Parameters 170 535 40.5 535 3000 1530 500

KORBA SIMULATOR

107

CURVES AFTER 48 HRS SHUTDOWN

Time Min.

Activity Main STM Press

KG/SQCM

Main STM

Temp. Deg. C

RH STM Press

KG/SQCM

RH STM

Temp. Deg. C

Turbine Speed RPM

Main STM Flow

T/HR.

Gen Load MW

000 Light Boiler & 00 130-160

---- ---- ---- ---- ----

Charges HP/LP

Bypass

180 51 365-375

---- ---- ---- ---- ----

210 Start Rolling 60 400 12 340 ---- ---- ----

219 Syncronisation 60 405 12 347 3000 140 ----

225 Close HP/LP

BP 60 407 14 355 3000 220 22

246 Cut In 1-st

Mill 78 420 18 377 3000 460 110

264 Cut In HP

Heaters 95 430 22 395 3000 680 185

270 Cut In 2-nd.

Mill 100 435 24 400 3000 760 210

282 Cut In 3-rd

Mill 112 442 26 415 3000 900 255

297 Cut In 4-th

Mill 125 452 30 430 3000 1080 320

309 Cut In 5-th

Mill 137 460 32 444 3000 1220 365

324 Cut In 6-th

Mill 150 470 36 460 3000 1400 425

342 Reach Full

Load 170 480 40 480 3000 1620 500

420 Reach Rated

Parameters 170 535 40.5 535 3000 1530 500

KORBA SIMULATOR

108

CURVES AFTER 8 HRS SHUT DOWN

Time Min.

Activity Main STM Press

KG/SQCM

Main STM

Temp. Deg. C

RH STM Press

KG/SQCM

RH STM

Temp. Deg. C

Turbine Speed RPM

Main STM Flow

T/HR.

Gen Load MW

000 Light Boiler & 76 415-430

---- ---- ---- ---- ----

Charge HP/LP Bypass

040 Cut In 1-st Mill

84 485-490

---- ---- ---- ---- ----

046 Cut In 2-nd.

Mill 86 495 ---- ---- ---- ---- ----

050 Start Rolling 87 500 12 ---- 3000 ---- ----

056 Syncronisation 87 500 12 460 3000 130 ----

060 Close HP/LP

BP 87 500 14 465 3000 240 40

065 Cut In 3-rd

Mill 96 500 20 480 3000 500 130

068 Cut In HP

Heaters 106 500 22 485 3000 640 170

070 Cut In 4-th

Mill 114 500 24 495 3000 740 210

073 Cut In 5-th

Mill 124 500 26 500 3000 880 260

076 Cut In 6-th

Mill 132 500 32 500 3000 1060 320

086 Reach Full

Load 170 500 40.5 500 3000 1610 500

135 Reach Rated

Parameters 170 535 40.5 535 3000 1530 500

KORBA SIMULATOR

109

TURBINE START-UP CURVES

WARMING-UP AND STARTING THE TURBINE TEMPERATURE CRITERIA

Fig: 1 STEAM WITH 50O SUPERHEAT

KORBA SIMULATOR

110

Fig: 2 RECOMMENDED MINIMUM CURVE (CURVE-A) AND MAXIMUM (CURVE-B) MAIN STEAM TEMPERATURE AHEAD

OF TURBINE WHEN OPENING THE MAIN STOP VALVES.

KORBA SIMULATOR

111

Fig: 3 ALLOWABLE MAXIMUM MAIN STEAM PRESSURE AHEAD OF TURBINE WHEN OPENING THE MAIN STEAM

STOP VALVES.

KORBA SIMULATOR

112

Fig: 4 RECOMMENDED MINIMUM MAIN STEAM

TEMPERATURE AHEAD OF TURBINE BEFORE OPENING THE MAIN CONTROL VALVES

KORBA SIMULATOR

113

Fig: 5 RECOMMENDED MINIMUM REHEAT TEMPERATURE

AHEAD OF IP TURBINE BEFORE OPENING THE REHEAT CONTROL VALVES

KORBA SIMULATOR

114

Fig: 6 RECOMMENDED MAXIMUM MAIN STEAM TEMPERATURE AHEAD OF TURBINE BEFORE THE

TURBINE IS BROUGHT TO RATED SPEED

KORBA SIMULATOR

115

Fig: 7 RECOMMENDED MAXIMUM MAIN REHEAT

TEMPERATURE BEFORE TURBINE IS LOADED

KORBA SIMULATOR

116

KORBA SIMULATOR

117

HOT START-UP PROCEDURE

KORBA SIMULATOR

118

KORBA SIMULATOR

119

HOT START UP PROCEDURE Check the following conditions exist immediately after the Unit Tripping. ��Generator /Field Breaker are tripped. ��UAT’s Supply to Unit Buses are tripped and Station Supply takes over automatically. ��Generator AVR trips to manual mode. ��All the turbine Stop valves are closed. ��CRH NRV at HPT Exhaust closed. �� Turbine trip oil , Aux Sec oil & Secondary oil pressure became Zero. ��All the Feed Water Heaters Extraction Block valves are closed automatically. ��Drain before HP control valves are closed. Verify �� Main Turbine Aux.Oil Pump1 starts automatically (if SLC is on). �� Turbine Gate valve Gearing is opened automatically at 210 rpm(if SLC is on ). �� JOP1 starts automatically if at 510 rpm if SLC is on. �� Turbine Gate valve gearing is opened automatically at 210 rpm(if SLC is on). �� Drum, SH/RH pressures rise on interruption of steam to turbine. �� HP/LP by pass open, if on Auto with proper set points. �� Condenser vacuum breaker may open if tripping is because of fire protection or Axial shift. �� SH/RH attemperation Block valves are closed if spray control valves are less

than 5% open.

�� Drum level may sink. �� All mills & Feeders with both PA fans tripped. �� HFO trip valve may close as per oil gun logics. �� Furnace vacuum dips to very low value due to implosion.

KORBA SIMULATOR

120

�� All wind box dampers open up after unit tripping. Stop one set of ID/FD fans to avoid forced cooling of the boiler.Stablise & maintain the draught & air flow. BOILER PURGE: Ensure all purge permissives are available & do furnace purging for 5 minutes. Boiler MFR (A&B) gets reset after a time delay of 5 minutes. The first cause of unit tripping gets reset along with the MFR reset.

Deaerator:

Ensure Deaerator pressure is maintained at 3.5 Kg/cm2 & auxiliary steam pressure is

14 Kg/cm2

Condenser: Establish condenser vacuum if it has deteriorated on protection. Turbo Generator reset: Reset Generator trip relay & Turbine trip. Starting device is brought to 0% and trip oil pressure comes to 6.8 Kg/cm2(approximately). Boiler Light up: Light up the boiler with the upper elevation oil guns and a mill or two is put in service if required to hold the temperature. Ensure that minimum stable fire is established in the boiler. Charging steam lines and heating: Open the following drain valves: 1. Drain before ESV seats. 2. Drain before IV seats.

KORBA SIMULATOR

121

3. MS strainer drain valves. 4. MS header drain valves. 5. HRH header drain valves. 6. CRH header drain valves. 7. Drain before Extraction NRVs and HPT exhaust NRV. 8. Drain after control valves. 9. HP casing drain. 10. Drain before and after IP control valves. HP/LP BP charging and temperature raising: Open HP Bypass valves so as to establish 15% flow through them,taking care to see

that temperature control loop is funtioning normally.

Ensure LP Bypass system is functioning normally on Auto.Adjust the fixed set point to

8 Kg/cm2.

Steam flow thus established shall assist in heating Main Steam, Cold Reheat and Hot

Reheat lines.

HPBypass valves can further be opened to assist in increasing steam parameters. TURBINE ROLLING AND SYNCHRONISING: Turbine can be rolled to rated speed either by ATRS rolling or manual rolling through

Electro Hydraulic Governor.

The following conditions are to be checked before rolling. �� The turbine should be on barring gear(115 rpm). �� Condenser pressure is less than 0.5 Kg/cm2 �� At least one condensate extaction pump is on. �� Trip fluid pressure is more than 5 Kg/ cm2.

KORBA SIMULATOR

122

�� Differential temperature between HP casing mid section top and bottom is less

than 300C.

�� Differential temperature between IP casing mid section top/bottom (Both front

and rear) is less than 300C.

�� HP control fluid temperature is maintained between 500C to 550C.

�� Lub oil temperature after cooler is more than 350C.(38-470C)

�� Degree of superheat of Main Steam before HP Bypass is more than midmetal

temperature of H.P.Control valves.

�� Main Steam pressure before turbine is function of mid wall temperature of

H.P.Control Valves.

�� Raise the Starting Device above 42% and then to 56%.

1) Verify that all ESVs have opened.

2) Verify that drains before HP Control valves are in Auto and these valves have

opened.

3) Put Seal Steam controller on Auto.

4) Verify that the following Generator conditions are fulfilled.

�� Any Generator bearing vapour Exhaust fan is on. �� Hydrogen Temperature controller is in auto. �� Hydrogen purity is more than 97%. �� Hydrogen pressure is more than 3 Kg/cm2. �� One Air side Seal oil pump is on. �� One Hydrogen Seal oil pump is on. �� Differential pressure between Seal oil Air side and Hydrogen side (both turbiine and Exciter end is more than 0.7 Kg/cm2)

KORBA SIMULATOR

123

�� Turbine side prechamber level is low. �� Generator bushing box liquid level is low(less than 90mm) �� One Primary water pump is on. �� Primary water temperature controller is on Auto �� Primary water conductivity is less than 1.5 Micro mho/cm. �� Primary water flow is adequate (>13.3dm3/sec) Before Opening the control valves, verify the following: a) The degree of Superheat of Main steam before turbine is more than 50°c. b) M.S.Temperature before turbine is more than either midwall temperature of HP

casing or Simulated mid section temperature of HP Shaft.

c) HRH temperature before turbine is more than simulated mid section

temperature of IP Shaft.

During the warm up and hot start up of the turbine, observe the following parameters. • Differential Expansions. • Axial Shift • Temperature difference between top and botttom of the HP/IP casings. • Bearing temperature and vibration. • Steam parameters. • TSE margin recorders for the following components HPS/HPC/IPS. • Operating parameters of condensing system. • Operating parameters of turbine oil & control fluid systems. Maintain MS Temperaurte and Pressure at turbine inlet as per Start up Curve. Turbine Rolling Raise the speed set point so as to admit steam to steam to the turbine & Start rolling. Raise the speed to 360 rpm for warming up the casing.

KORBA SIMULATOR

124

Verify that Gate valve gearing has closed. Close all the drains valves as mentioned earlier for warm up of steam lines. While admitting steam to the turbine, ensure that permissible wall temperature of

limit curves are not exceeded.

Hold the speed at 360 rpm for soaking purpose. Close the drains before HPCVs. Close the drains after HPCV if differential temperature between HPCV & Saturated

steam is more than 50°C.

Raise the speed to 3000 rpm provided the following parameters are with in the limits. a. The Differential Expansion of the casing. HP Turbine IP Turbine LP Turbine +5mm to -3mm +8mm to -2mm +30mm to -3mm b. The differential temperature between the top & bottom of the casing less than +

450C.

c. Bearing temperature and vibration are less than 900C and 45 microns

respectively.

d. HP Turbine exhaust hood temperature is less than 5000C. AT 3000 rpm Verify that the following conditions are fulfilled. 1) Both AOP’s are off. 2) HRH temperature before LP bypass is greater than IP shaft mid metal temperature. 3) Cold Hydrogen gas temperature is less than 450C. 4) Main Exciter hot air temperaurte is less than 450C. 5) Cold primary water temperature is less than 500C.

KORBA SIMULATOR

125

6) Cold Primary water flow through bushing is more than 0.37 dm3/sec and windings is more than 13.3 dm3/sec. 7) Differential temperature between primary water & Hydrogen is more than 10C. Synchronising and Load Raising: a) Put AVR on Auto & Switch on field Breaker. b) Verify that Generator terminal voltage is 95%. c) Switch on the Synchroniser & synchronise the Generator with Grid when

incoming Frequency, Voltage and Phase sequence match with the running

system.

d) Raise the Starting device and take a block load of 10% by raising Nref from

AVR console/Turbine console.

e) Close HP Bypass and check LP Bypass closes on Auto, when sliding set point is

more than Hot reheat Pressure.

f) Charge Unit Auxiliary Transformer to change over 6.6 KV supplies from Station

to UAT.

g) Raise the Turbine inlet Main Steam Pressure at the rate of 0.8 Kg/cm2 per

minute up to Kg/cm2 at 25 % load and after wards at 1.65 Kg/cm2 per minute

such that rated throttle pressure is achieved at 55 % load.

h) Raise turbine inlet Main steam temperature at the rate of 1.60C /minute upto

485°C at 50% load.

i) Close HP casing drain valve provided HP casing bottom temperature is more

than 3000C.

j) Verify that drains before HP Turbine exhaust NRVs have closed with the

opening of NRVs.Close the drains before and after IPCVs when difference

KORBA SIMULATOR

126

between IPCV and Hot Reheat steam is more than 500C.Open the Extraction

steam block valves to LPH 2, 3 & Deaerator.

�� Main steam temperature can be raised at the rate 1.60C up to 4850C and at the

rate of 0.60C above 4850C till it reaches 5400C.

�� Raise the turbine load at the rate of 4 MW/min up to 125 MW. �� Verify that drain before LPH 2&3 closed when opening of respective extraction

NRV is more than 15%.

�� Verify that drain before Deaerator extraction line NRV closes when opening

extraction NRV is more than 15% & differential pressure across NRV is more

than 300mm wc.

�� Put Hot well level control and deaerator level control on auto. �� Above 20% Boiler Load Index, drum level three element control can be put on auto. �� Raise the Turbine load at the rate of 2 MW/min to 485 MW. �� AT 27% Turbine load, cut in the first mill and at 43% turbine cut in the second mill. �� AT 40% Turbine load, combustion controls can be put on auto. HP Heaters 5 &

6 can be taken into service.

�� Around 50 % Turbine load, cut in the second set of Boiler and Turbine

Auxiliaries such as I.D.Fan, F.D.Fan, P.A.Fan, Boiler Circulating Pump,

Condensate Extraction Pump and the second Boiler Feed Pump.

Mills are put in operation in the following sequence: No of mills Turbine load IIIrd 50% IVth 60% Vth 70%

KORBA SIMULATOR

127

Vth 74% Above 55% Boiler MCR,SH,RH temperature controls can be put on Auto. Between 50% and 75% load,maintain turbine inlet main steam temperature at 4850C. From 97% to 100% turbine load, raise the turbine inlet temperature at the rate of

0.60C per minute to 5350C.

KORBA SIMULATOR

128

KORBA SIMULATOR

129

SHUT-DOWN PROCEDURE

KORBA SIMULATOR

130

KORBA SIMULATOR

131

SHUTDOWN PROCEDURE TURBINE LOAD REDUCTION WITH COORDINATED CONTROL SYSTEM(CCS) OBJECTIVE • To reduce the loading on the turbine for a planned shut down. OPERATIONAL STEPS 1. Ensure that unit is on coordinated mode with limit pressure mode in service

and boiler master in auto mode.

2. Check the load gradient is set at 5 MW/min on both the consoles. 3. Reduce the unit master set point (load demand) to 400 MW. 4. Take the attemperation control in manual mode and slightly raise the

controller output to bring down the main steam and reheat temperature.

5. Check that the load reference set point comes down and boiler master reduces

its output to reduce firing.

6. Reduce the AVR set point by pressing the lower button on AVR insert. 7. Check that all the pulveriser coal flow reduced equally. 8. Check that all HP control valve opening reduces and load come down to 400

MW.

9. Gradually reduce the throttle pressure set point to about 130 Kg/cm2. 10. Turn the burner tilts to lower side by decreasing the controller output. 11. Check that fuel flow starts coming down followed by the air flow and steam

flow.

12. Check that the main steam pressure and cold reheat pressure also starts dropping. 13. The ESV surface temperature starts dropping followed by the mean

temperature, same is the case for the control valve also.

14. Further drop the main steam and reheat temperature to cool the turbine. The points shown by the TSE 12 point recorder shows the decreasing trend.

KORBA SIMULATOR

132

15. Take unit on Turbine Follow Mode 16. Stop the topmost pulveriser to reduce the firing. Reduce the output of fuel

master manually.

17. Close the extraction block valves to HP heater 6B and 5B from steam side. The

valve starts closing, the drain control valve also starts closing since there is no

steam flow to the heater.

18. The boiler pressure increases momentarily then drops down as the feed water

temperature has reduced.

19. Further reduce the output of the fuel master to reduce the firing and steam

temperatures. Ensure that the unit is in turbine follow mode with initial

pressure control mode in service.

20. The load will drop automatically in turbine follow mode to maintain the

pressure set point.

21. Stop one more pulveriser to reduce the firing. Reduce the out put of fuel

master manually.

22. Maintain the furnace pressure, boiler drum level and primary air header

pressure during this transient.

23. Check that HP casing temperature and HP shaft temperature (calculated) drops

as per the main steam temperature.

24. Check the flame intensity at elevation corresponding to running feeders and

also the furnace pressure.

* Unit load reduced to 75 % *

KORBA SIMULATOR

133

PULVERISER SHUT DOWN OBJECTIVE • To reduce the loading and take out the pulveriser in service. OPERATIONAL STEPS 1. Select the pulveriser which is at the top most elevation. 2. Take the feeder speed control in the manual mode and reduce the loading of

the feeder to minimum.

3. Close the hot air gate from the FSSS console. Cold air damper opens 100 %

and hot air damper closes fully.

4. Check that mill outlet temperature drops rapidly and Mill current also comes

down.

5. Stop the feeder by depressing the feeder stop button. The coal flow drop to

zero. The loading in other pulverisers will increase to compensate the lost coal

supply.

6. Wait till the pulveriser grinding current comes to no load current. Check that

mill outlet temperature and bowl differential pressure comes down.

7. Decrease the fuel air damper opening to almost close condition. 8. Check that feeder voted light (no flame)comes once the feeder is stopped. 9. Open the tramp iron gate to remove any rejects accumulated in pulveriser. 10. Stop the pulveriser by depressing pulveriser stop push button. Check that the

cold air damper closes full and mill air flow drops down.

11. Maintain the PA header pressure to normal value. 12. The pulveiser seal air valve will close on interlock. 13. Close the pulveriser cold air gate from local. 14. Close the pulveriser discharge valves by depressing the close push button from

FSSS console.

15. Close bunker gate (Silo gate)

* Pulveriser taken out from service *

KORBA SIMULATOR

134

LOAD REDUCTION AND HP/LP BYPASS OPERATION OBJECTIVE • To reduce the load below 50 % and stop one set of auxiliaries. • To take HP/LP bypass in service to avoid oil support. OPERATIONAL STEPS 1. This step is in continuation with the operating instructions given earlier where

the unit load is 75 % with four pulverisers.

2. Check that the turbine pressure controller is active and unit is in turbine follow

mode from coordinated control system CCS.

3. Reduce the fuel input by decreasing the fuel master controller.

4. Check the overall flame stability within furnace and the analog output of the

scanner flame indication.

5. Reduce the set point of AVR.

6. Reduce the main steam temperature and hot reheat steam temperature by

raising the attemperation flow.

7. Reduce the throttle steam pressure set point gradually by lowering the S/P on

coordinated control system console.

8. Transfer the furnace pressure controller to manual mode and reduce the

loading on one ID fan and load the other fan.

9. Transfer the FD blade pitch control to manual mode and unload the FD fan

corresponding to above ID fan which is unloaded .

10. Maintain the furnace pressure and air flow during above operation.

11. Stop one ID fan and one PA fan by giving a stop command from UCB control

desk hand switch. The breaker opens, green off indication lamp comes.

KORBA SIMULATOR

135

12. Ensure the flame stability within the furnace, if necessary cut in the oil

support. Three feeders with loading above 75 % may not need the oil

support.

13. Check that the inlet/outlet dampers of ID fan and discharge damper of the FD

fan closes on auto.

14. Adjust the HP bypass pressure set point to match existing throttle pressure.

15. Transfer the initial pressure mode to limit pressure mode and reduce the

throttle pressure set point to keep the deviation positive.

16. Reduce the target load set (load reference) value from the governing console i.e.,

pr ref. & pr lim comes down at a rate set by the load gradient.

17. Ensure that LP bypass controller is kept on auto with fix set point slightly

below the sliding set point.

18. As the throttle pressure increases on reduction of load the HP bypass valves

will open on auto causing the cold reheat pressure to go up. Once this

pressure exceeds the sliding set point, LP bypass valves will also open.

19. Further reduce the load set point from governing console. Check that the

opening of HP bypass valves increases further. The hot reheat temperature

can be controlled by controlling cold reheat temperature by HPbypass

attemperation valves.

20. Change over from unit supply to station supply for 6.6 KV A and B buses using

synchroscope.

21. Cut in oil support at AB elevation with minimum oil pressure to stabilise the

flame.

22. Transfer all the three running feeders to manual mode by pressing the middle

switch and reduce the loading in one of the pulverisers.

KORBA SIMULATOR

136

23. Take out top pulveriser.

24. Close the extraction steam block valves to LPH1, 2 & 3 once load has come

below 20 %. Check that the drain control valve closes. Open the drains of the

extraction line.

25. Transfer the low load feed regulating station to auto mode and take the three

element feed water control to manual mode.

26. Stop one CEP also by giving a stop command from the UCB hand switch after

opening the recirculation valve fully.

27. Cut in one more oil elevation and maintain the oil pressure & temp.

28. Change over the 16 ata header from existing unit by opening the tie valve.

29. reduce the attemperation if the main steam temperature has come to around

3800C.

30. Maintain the hot well, deaerator level during this transient operation.

* Unit load reduced below 50 % with HP / LP bypass in service. *

TURBINE ON BARRING GEAR OBJECTIVE • Putting turbine on barring gear OPERATIONAL STEPS 1. At about 540 RPM ensure that jacking oil pump takes start and jacking oil

pressure comes to about 125 Kg/cm2.

2. At about 210 RPM check that the barring gear valve starts opening and turbine

speed is maintained to about 190 RPM.

3. Open the HP casing drain manually after switching off the SLC. 4. Open all the four drains upstream interceptor valve at valve seat. 5. Open the main steam header drain valve

KORBA SIMULATOR

137

6. Open the drains upstream of ESV at valve seat 7. Ensure the SLC drain for various drain valve in ‘ON’. 8. Check the differential expansions of all the three casing within limits. 9. Check the bearing temperature for all the bearing should start coming down. 10. Stop one pulveriser and maintain the PA header pressure. 11. Check that the seal steam pressure is maintained and condenser vacuum

satisfactory.

12. Reduce the fixed set point of LP bypass to maintain flow through reheaters. The

opening of the LP bypass control valve increases.

13. Reduce the attemperation controllers to minimum for SH and RH.

* The turbine on barring gear * BOILER SHUT DOWN OBJECTIVE • To trip the boiler and carry out the purging. • To fill the boiler to highest drum level. OPERATIONAL STEPS 1. Ensure that unit status is safe. 2. Take the HP/LP bypass valves in manual mode and reduce the opening of HP /

LP bypass.

3. Stop bottom pulveriser as per the instruction given earlier. 4. Check that all the fuel air dampers close from top to bottom. 5. Bring the burner tilt to horizontal position. 6. Check that start permit is available, burner tilt horizontal and air flow less

than 40 %.

KORBA SIMULATOR

138

7. Remove the oil guns at CD elevation by pressing pair 1-3 and 2-4 stop push

buttons.

8. Check that 5 min. scavenging operation is complete and gun retracts back. 9. Remove the oil guns at AB elevation. 10. The moment oil nozzle valve for 4th corner closes, the boiler will trip and loss of

all fuel to furnace alarm will come.

11. MFR tripped alarm comes. Both the MFR A/B relays trip red lamp comes. 12. Check that HOTV closes and green lamp comes on. 13. Bring the air flow to less than 40 % by FD fan blade pitch. 14. Check that all the purge permissives are satisfied and purge ready lamp comes. 15. Close the HP/LP bypass manually and increase the set pressure higher than

the existing pressure.

16. Push the ‘Push to purge’ switch from FSSS console. The purging light glows

and stays for 5 mins. and purge complete light comes once purging is over.

The MFR A and B relays reset.

17. Wait till the fuel air damper starts closing from top. Maintain the air flow in

between 30 to 40 %.

18. Raise the BFP discharge pressure by raising the speed of BFP turbine.

19. Open the low range feed control valve to start the drum filling . Check that the

level in drum which will gradually increases.

20. Stop the drum filling once all the ports of the hydrastep are indicating water

(green lamps on). Ensure that blow down valves are closed including

emergency blow down.

21. Stop the HP dosing system from local.

KORBA SIMULATOR

139

22. Stop the boiler feed pump A by pressing the turbine trip push button. Check

that the EHC position drops to zero and control valve closes.

23. Ensure that barring gear of the BFP turbine engages.

24. Close the auxiliary steam block valve to TDBFP

25. Stop the LP dosing pump from CSSAEP.

26. Close the manual isolating valve to HP bypass desuperheating valve from local. 27. Check that BFP discharge pressure and flow drops to zero. 28. Close the equipment cooling water to MD BFP motor. * Turbine on barring gear with boiler in tripped condition, drum filled upto

the top * SHUT DOWN OF AIR AND FLUE GAS SYSTEM. OBJECTIVE • To stop the ID fans, air preheaters. • To stop the FD fans, scanner air fans. OPERATIONAL STEPS 1. Check the plant status with boiler in tripped condition and purging carried out. 2. In manual mode reduce the FD fan blade pitch to 0 %. Check that the air flow

reduces and generates an alarm below 30 %.

3. Check that first cause of trip red flags comes on FSSS console as air flow is less

than 30 %. Both the MFR trip and red lamp comes on.

4. Stop the FD fan by turning the switch to OFF position.

5. Check that the fan current drops down to zero and discharge pressure starts

dropping down.

6. Check that discharge dampers of both the fans open fully. 7. Check that scanner fan emergency damper from atmosphere opens

KORBA SIMULATOR

140

8. Stop the ID fan by turning the switch to OFF position . 9. Check that the fan amps drops down to zero and inlet/outlet pressure decreases. 10. Ensure that the dampers for all three fans GD-20 to GD-25 opens fully on

interlock .

11. Keep the lub oil pumps of all the fan running till the bearing temp. of the fans

come down.

12. Check that the flue gas temp. entering the air heater goes less than 120oC.

Stop sec. RAPH A and B motor from UCB manually. [ Note that air motor will

not take auto start.]

13. Similarly stop the primary SCAPH A and B 14. Keep open all the flue gas inlet/outlet dampers on air side as well as flue gas

side in order to allow the natural air circulation for cooling.

15. Check and close all air preheater cold end temp. controllers. 16. Close the steam inlet valves to primary and secondary RAPH A and B. 17. Stop the ash slurry pumps and bottom ash transport pumps. 18. Ensure that ESP fields are not charged . 19. Stop the DC scanner air fan from FSSS console, once the furnace is sufficiently cooled.

* Flue gas and air path equipments taken out of service *

KORBA SIMULATOR

141

SHUT DOWN OF TURBINE SIDE AUXILIARIES OBJECTIVE • To kill vacuum and stop vacuum pumps. • To stop control fluid pumps. • To stop the turbine lub oil system OPERATIONAL STEPS 1. Check that the plant is in safe condition. 2. Ensure that turbine is on barring gear with circulating water system in service. JOP should also be in service. 3. Transfer the SLC drain to auto mode and check the drain valves are

modulating as per their logic.

4. Stop the vacuum pump No. 1 from the oil console insert. 5. Close the air isolation valve and hold the command till the valve is fully closed. 6. Open the vacuum breaker from the insert. Check that vacuum falls rapidly. 7. Take the gland seal steam controller to manual mode and close it fully. Open

the gland seal steam drain valve fully.

8. Close the block valve for seal steam supply to glands ASD-006. 9. Stop the seal steam exhauster. 10. Change the status of the vacuum pump ‘lined up’. 11. Switch off the SLC of both the pumps . 12. Stop the control fluid pump.Check that the pump current drops down to zero.

The control fluid discharge pressure starts dropping.

13. Switch off the HP control fluid heater No. 1 from the console insert. 14. Isolate the control fluid cooler from water side by closing the inlet outlet valves

and open the drain.

15. Isolate the high pressure accumulator by closing the isolating valves.

KORBA SIMULATOR

142

16. Close the high pressure and low pressure discharge valves. 17. Check that turbine side temperatures (e.g. HP shaft, HP casing, IP shaft etc.)

has come down below 75oC. from TSE recorder.

18. Check that the differential expansions for all the three casing are within limit. 19. Ensure from DAS and local also that turbine metal temperatures are below 75oC. 20. Switch off the SLC of the gate valve gearing. 21. Close the gate valve gearing by pressing the left side push button. 22. Check that turbine speed gradually comes down. 23. Once the turbine is stand still the jacking oil pump can be stopped. 24. Switch off the SLC for jacking oil pumps. 25. Switch off the jacking oil pump N0. 1 by pressing the left side push button.

Check that the pump current drops down to zero.

26. Purge the hydrogen from the generator and fill with the carbon di-oxide. 27. Ensure that Hydrogen is removed before stopping the barring gear. 28. Ensure that CO2 occupies the generator space. This can be checked from the CO2/O2 purity meter. 29. De-pressurise the generator by removing the carbon dioxide. Ensure that no

hydrogen cylinder is connected at gas filling header.

30. Stop the seal oil pumps from local. 31. Isolate seal oil cooling system from local.

32. Close the stator water cooling system manual isolating valve from local. (Stator

water running in bypass conditions)

33. Stop the generator bearing chamber exhaust fan. 34. Isolated the G.T cooling water circuit from local .

KORBA SIMULATOR

143

35. Switch off the SLCs of the AOP 1 & 2 and EOP. Check that left side amber

lamp comes.

36. Check from the local (exciter end) that turbine has come to stand still. 37. Switch off the auxiliary oil pump. Check that the current drops down to zero. 38. Ensure that lube oil pressure drop down slowly 39. Check that EOP and AOP-2 do not take start as their SLCs are off. 40. Isolate the turbine lube oil coolers from water side. 41. Switch off the oil vapour extractor by pressing left side push button. 42. Take the oil temperature controller in manual and close it. * The condenser vacuum killed. Turbine / Control oil and lube oil system taken

out of service. *

SHUT DOWN OF CONDENSATE SYSTEM OBJECTIVE • To stop the condensate pump this is in service. • To stop the make up pumps and associated system. OPERATIONAL STEPS 1. Check that the plant status is safe, with turbine side equipments stopped. 2. Ensure that the Dea. Level controller is in closed condition and in manual

mode.

3. Close the block valve of the Dea. Level controller station CO-14 CO-17. 4. Close the emergency make up controller as the condensate pump is running on

recirculation only.

5. Keep the selector switch of the CEP - B and C in normal position to prevent

their auto start on low discharge header pressure.

6. Stop the CEP- A by turning the switch to stop position. The CEP stops and

breaker off green lamp comes on.

KORBA SIMULATOR

144

7. Check that CEP discharge flow and current comes down to zero. 8. Ensure that discharge valves of all the three CEP should close. 9. Check that vent valve on turbine oil system opens on auto as all the CEPs are

off.

10. Check that hotwell level is in steady state, if increasing then check the make

up controllers, if open, close them.

11. Ensure that all the recirculation controllers are full open and are in manual

mode .

12. Close the sealing line valve from common discharge from local . 13. Ensure that condenser spill valve bypass and condensate fill valves are closed 14. Rack out the breakers of CEP from swgr . 15. Close the suction valve for all three CEPs from local . 16. Close the ECW inlet and outlet valve of the CEP bearing oil coolers 17. Close the GSC minimum flow isolating valve from local . 18. Ensure that all the make up control valves along with there by-pass valves are in

closed condition from UCB.

19. Change the emergency make up pump control status from auto to manual . 20. Stop the hotwell make up pump from local . 21. Stop the emergency make up pump- A from DM plant . 22. Check that make up flow to hotwell shows zero value.

* Condensate pump taken out of service *

KORBA SIMULATOR

145

SHUT DOWN OF CIRCULATING WATER SYSTEM. OBJECTIVE • To stop the circulating water pumps and associated system. OPERATIONAL STEPS 1. Check that condenser vacuum is killed. 2. Close the CW-inlet valve at condenser - A & B 3. After a time delay gradually throttle the condenser outlet valve. 4. Stop any one of the CW pumps. Both pumps should not be stopped as ARCW

pumps are still running and the suction is taken from CW inlet duct.

5. Check that the discharge valve of CW pump which is taken out of service closes.

6. Stop the travelling water screen corresponding to CW pump which is off. 7. If required open the water box vents on the condenser Note : Both the CW pumps should not be taken out of service till the ARCW pumps

are in service.

* Circulating water system taken out of service* SHUT DOWN OF FUEL OIL SYSTEM. OBJECTIVE • To stop heavy fuel oil pumps and associated system. OPERATIONAL STEPS 1. Close the oil temperature control valve to reduce the steam supply to HFO

heaters.

2. Close the short recirculation valve HO - 27 from UCB 3. Stop one HFO pump from local . 4. Check that HFO pressure drops slightly on UCB indicator 5. Close the discharge valve of the HFO pump to isolate the HFO heater.

KORBA SIMULATOR

146

6. Open the heater drain and vent after closing the steam valve to the heater. 7. Repeat the above steps to take second pump out of service. 8. Close the HFO delivery valve (HO - 18) and inlet to the firing floor (HO - 25)

valves.

9. Isolate the suction valves to both the pumps and drain the pump. 10. Isolated the steam lines going to pump jacket and strainers. 11. Stop the HFO tank heating if long shut down is expected. 12. Isolate the auxiliary steam supply to the HFO pump house and open the

various line drains.

* HFO pump taken out of service * SHUT DOWN OF ECW SYSTEM OBJECTIVE • To stop the DMCW pumps and associated systems. • To stop the ARCW pumps and associated systems OPERATIONAL STEPS 1. Check that the plant status is safe and no major auxiliaries running. 2. Isolate the cooling water inlet valve to ID fan A/B/C. 3. Isolate the cooling water inlet valve to FD fan A/B/C lub oil systems from local. 4. Isolate the various auxiliary cooler and isolate the differential pressure

regulators such as PCV-1145,PCV-1144 for BFP, CEP etc.

5. Select the pump which is to be stopped from the selector switch. 6. Stop one DMCW pump by turning the hand switch to off position. 7. Check that the motor current drops down to zero and discharge pressure drops

slightly.

8. Close the pump discharge valve from CM-1101 of CSSAEP.

KORBA SIMULATOR

147

9. Repeat the above steps to stop the second DMCW pump. 10. Check that the discharge pressure & the motor current drops down to zero. 11. Stop CW pumps from local . 12. Keep the selector switch to off position for ARCW pump from CSSAEP 13. Stop ARCW pump A by turning the switch to off position. 14. Check that the current drops down to zero and main CW pressure at heat

exchanger outlet drops slightly.

15. Stop ARCW pump B also by turning the switch to off position. 16. Close the discharge valves of ARCW pump A & B, both valve close and green

lamp comes on.

17. Unit - 6 ARCW pump discharge header pressure low alarm comes in. 18. Isolate the plate type heat exchanger by closing the inlet and outlet valves. 19. Open the pump drain and vent valve to drain the pump. 20. Close the suction valve of the ARCW pumps. 21. Switch off the electrical power to the ARCW pump since the suction valve is

closed.

• ARCW pump and ECW pumps taken out of service * •

SHUT DOWN OF AUXILIARY STEAM SYSTEM. OBJECTIVE • To isolate the 16 ata steam header and associated system. OPERATIONAL STEPS 1. Check that the plant status is safe with boiler in tripped condition and turbine

auxiliaries taken out of service.

2. Close the primary SCAPH A / B steam inlet valves if not done earlier. 3. Close the auxiliary steam to burner atomising and HFO heating.

KORBA SIMULATOR

148

4. Close the deaerator pegging steam valve from auxiliary steam, if open and

ensure that pressurisation of D/A due to aux. steam does not take place any

further.

5. Reduce the auxiliary steam pressure controller output manually, if the

auxiliary steam is still through the cold reheat line.

Note : Since the auxiliary steam header can be charged either from cold reheat line

or from unit 7 or also from the existing 20 MW aux. boiler should be

isolated by closing the respective valve through which it is charged.

6. Ensure that motorised isolating valves to TDBFP, ASL-004 and gland steam

ASH- 006 are closed.

7. Open the header drain valve AS-73 from local.

8. Check that the temperature control valve is fully closed.

9. Check that the auxiliary steam pressure shown by UCB indicator comes down

to zero.

10. Open various steam traps and drains for the atomising line and steam tracing

line all over the boiler.

11. Ensure that gland steam line drains from auxiliary steam are opened.

* Auxiliary steam header isolated. *

KORBA SIMULATOR

149

FURNACE SAFEGUARD AND SUPERVISORY SYSTEM

KORBA SIMULATOR

150

KORBA SIMULATOR

151

FURNACE SAFEGUARD SUPERVISORY SYSTEM (FSSS) INTRODUCTION The Furnace Safeguard Supervisory System (FSSS) is designed to ensure the execution of a safe, orderly operating sequence in the start-up and shutdown of fuel firing equipment and to prevent errors of omission or commission in the following such as safe operating procedure. The system provides protection against malfunction of fuel firing equipment and associated air systems. The safety features of the system are designed for protection in most common emergency situations; however, the system cannot supplant the intelligent and reasonable judgement of the operator in all situations. In some phases of operation, the Furnace Safeguard Supervisory System provides permissive interlocks only to ensure safe start-up sequences of equipment. Once the equipment is in service, the operator must use normally acceptable safe operating practices. It is important that the operator is familiar with the overall operation of the unit and the operation of individual equipment, as outlined in the section “Unit Operating Procedures” and the various individual equipment sections in this manual. It is essential that all parts of the Furnace Safeguard Supervisory System are operable and in service at all times if the system is to provide the protection for which it is designed. Adequate maintenance and periodic inspection of the system and associated hardware is essential for its continued proper operation. This instruction section of the manual gives a complete description of the Furnace Safeguard Supervisory System furnished for this Unit as it relates to the various unit operating phases and the operation of the fuel firing equipment and associated air systems. Basically the system is designed to perform the following functions : a. Prevent any fuel firing unless a satisfactory furnace purge sequence has first

been completed. b. Prevent start-up of individual fuel firing equipment unless certain permissive

interlocks have first been satisfied. c. Monitor and control proper component sequencing during start-up and shut

down of fuel firing equipment. d. Subject continued operation of fuel firing equipment to certain safety interlocks

remaining satisfied. e. Provide component status feedback to the operator and, in some cases to the unit

control system and/or data logger.

KORBA SIMULATOR

152

f. Provide flame supervision when fuel firing equipment is in service and effect an elevation fuel trip or Master Fuel Trip upon certain conditions of unacceptable firing/load combinations.

g. Effect a Master Fuel Trip upon certain adverse Unit operating conditions. The method of accomplishing the logic in this unit is with C - E / Sulzer solid state logic system. There is a Logic Cabinet Assembly which contains control hardware in separate sections of the cabinet. Each section controls the following functions in the unit. 1. Power Distribution section. 2. Two sections for the unit. 3. Each of the four oil elevation (AB,CD,EF and GH) has a section for the oil

elevation and associated Safe Scan equipment. 4. There are separate sections for each coal elevation (“A” thru “H”). 5 “Fireball” flame scanner section. There is also a Unit Simulator panel assembly located on a swing panel in the Unit section. There are also four Oil Elevation Simulator panel assemblies. Each Simulator is located on a swing panel located in the associated oil elevation section. Each of the eight coal elevation sections has a Coal Elevation Simulator which is located on a swing panel in the associated coal elevation section. The Unit contains four (4) elevations of HEA ignitors, four (4) warm-up elevations and eight (8) coal elevations. Flame monitoring is accomplished with four (4) elevation of “Safe Scan” equipment and five (5) elevations of “Fireball” (Series 510) flame scanners. The “Safe Scan” equipment is used as discriminating flame scanner. This equipment is the Safe Scan 1-”Rear Access” model. OIL RECIRCULATION When all heavy oil nozzle valves are closed (PURGE PERMITS (White)”NOZL VALVS CLOSED” light is on), the heavy oil recirculation valve can be opened to head the heavy oil to obtain the proper viscosity for efficient combustion. This is accomplished by depressing the H.O. RECIRC. VLV “OPEN” push button. When the heavy fuel oil recirculation valve is moved from the closed position, the associated (red) “OPEN” push button is illuminated. The recirculation valve is proven

KORBA SIMULATOR

153

fully open when the associated (green) “ CLOSE” light goes off. When the recirculation valve is proven fully open, the heavy oil trip valve can be opened to heat the oil to the “proper” temperature (see “Heavy Oil Trip Valve Operation” section for specifics). The heavy oil recirculation valve can be closed by depressing the H.O. RECIRC. VLV “CLOSE” push button. The heavy oil recirculation valve is closed automatically when any heavy oil nozzle valve is not closed (PURGE PERMITS (WHITE) “ NOZL VALVES CLOSED” light goes off). UNIT START-UP FURNACE PURGE Before any fuel firing can take place (initially or following a boiler trip), a satisfactory purge cycle must be completed. All of the conditions listed below must be satisfied. To start a furnace purge cycle, proceed as follows: 1. The A.C. and D.C. power requirements are satisfied when the following conditions

are satisfied : A. Loss of ACS power for more than two seconds does not exit. The “LOSS OF ACS

POWER” signal at the Data Logger is removed. B. Loss of customer 220 VDC Battery power for more than two seconds does not

exist. The “LOSS OF 220 VDV> 2 SEC” signal at the Data Logger is removed. C. Loss of customer 220 VDC Battery power for more than two seconds does not

exist. The “LOSS OF UNIT CRITICAL POWER” signal at the Data Logger is removed. 2. The “Mode Permit” signal is proven established when the PURGE PERMITS

(white) “MODE PERMIT “ light is on. 3. A “ Simulator Trip” signal does not exist. The “SIMULATOR TRIP” signal at the

Data Logger is removed. 4. Both “Drum level high” signals from the Acs or the HYDRA STEP do not exist for

more than ten seconds. The “DRUM LEVEL LOW” signal at the Data logger is removed (See Note 1).

5. Both “drum level low” signals from the Acs or the HYDRA STEP do not exist for

more than ten seconds. The “DRUM LEVEL LOW” signal at the Data logger is removed (See Note 1).

KORBA SIMULATOR

154

NOTE 1 When items 4 and 5 above are simultaneously satisfied, the PURGE PERMITS (White) “DRUM LVL. SATIS.” light comes on. 6. When at least one boiler feed pump is not off, the “BOILER FEED PUMPS

TRIPPED” signal at the Data Logger is removed. 7. The “inadequate waterwall circulation” signal does not exit. The “INADEQUATE

W.W. CIRCULATION” signal at the Data Logger is removed. 8. Both P.A. (primary air) fans are proven off when the PURGE PERMITS (White)

“P.A. FANS OFF” light is on. 9. When at least one of the three (Induced Draft) fans are proven not off, the “All I.D.

FANS OFF” signal at the Data Logger is removed. 10. When at least one of the two F.D. (Forced Draft) fan is proven not off, the “BOTH

F.D. FANS OFF” signal at the Data Logger is removed. 11. When the air flow is greater than 30%, the “AIR FLOW < 30% TRIP” signal at the

Data logger is removed and the PURGE PERMITS (White) “AIR FLOW > 30 %” light comes on.

12. The auxiliary air dampers are proven modulating on all nine elevations when the

PURGE PERMITS (White) “AUX AIR DMPRS MOD” light comes on (See “Post Purge Excursion Protection” section for specifics.

13 The windbox to furnace differential pressure is proven satisfied when the PURGE

PERMITS (White)”W/B FURN P SATIS” light comes on. 14 The Deaerator Level is “not low-low” when the “LOW/LOW DEAERATOR LEVEL”

signal at the Data Logger is removed. 15 When all of the purge requirements are proven satisfied, the PURGE CYCLE

(White) “PURGE READY” light comes on (See Note 2). NOTE 2 If the light does not come on after items 1 thru 14 mentioned above have been satisfactorily completed, check to ensure that all of the following conditions are satisfied. A. A “furnace pressure high trip” signal does not exist. The “FURN PRESS HIGH”

signal at the Data Logger is removed.

KORBA SIMULATOR

155

B. A “furnace pressure low trip” signal does not exist. The “FURN PRESS LOW” signal at the Data Logger is removed.

C. The heavy fuel oil (H.F.O) trip valve is proven closed when PURGE PERMITS

(White) “TRIP VLV CLOSED” light is on. D. The H.F.O nozzle valves on all four oil elevation are proven closed when the

PURGE PERMITS (White) “NOZL VALVES CLOSED” light is on. E. The pulverizers on all eight coal elevations are proven off when the PURGE

PERMITS (White) “PULVS OFF” light is on. G. All hot air gates are proven closed when the PURGE PERMITS (white) “HOT AIR

GATES CL.” light is on. H. The flame scanners on all nine elevations indicate “no flame” when the PURGE

PERMITS (white) “SCANRS NO FLAME” light is on I A “no boiler trip command” exists. This is indicated by the PURGE PERMITS

(white) “ NO B.T.” light being on. When items 2,11,15c,15d,15e,15f and 15h mentioned above are satisfied, a five minute counting period is started (see “ Post Purge Excursion Protection” section for specifics). After the “PURGE READY” light comes on, the furnace purge cycle can be started. The PURGE CYCLE (green) “ PUSH TO PURGE” light will also be on because a master fuel trip memory signal exists at MFT “ A” and/or MFT “B” (the (red))” MFT A TRIP” and /or “MFT A TRIP” and / or “MFT B TRIP” lights are on). The furnace purge cycle is started when the “PUSH TO PURGE” illuminated push button is momentarily depressed. This action will turn on the PURGE CYCLE (amber) “PURGING” light and start a five minute counting period. The “PURGING” light remains on during the entire counting period (see Note 3) NOTE 3 If the “PURGING” light goes off before the five minute counting period expires, this indicates that at least one purge permissive is no longer satisfied (item 1 thru 15 above). The purge permissive must be re-established (“PURGE READY” light is on) and another furnace purge cycle started by momentarily depressing the “ PUSH TO PURGE “ push button. When the five minute counting period expires (and the “PURGING” light remained on), a successful furnace purge cycle has been completed and the following events will now occur: 16 The PURGE CYCLE (yellow) “ PURGE COMPLETE” light comes on.

KORBA SIMULATOR

156

17 The Data Logger receives a “PURGE COMPLETE” signal. 18 Two separate “no master fuel trip” memory signals are established, causing the following events to occur: A. The (green) “MFT A RESET” and “MFT B RESET” lights come on. B. The (red) “MFT A TRIP” and “MFT B TRIP” lights go off. C. The PURGE CYCLE (green) “ PUSH TO PURGE” light goes off. D. The (amber) “PURGE “ light goes off. E. The “ boiler load greater than 30 %” memory is now “armed”. F. The “MFT A TRIPPED” and “MFT B TRIPPED” signals at the Data Logger are

removed. G. The pulverizer’s and feeder’s can now be placed in the AUTO mode of operation,

when it is deemed necessary H. The pulverizer’s and feeder’s can now be placed in service after other permissives

are satisfied. I. The “trip primary air fans” signal is removed. The “TRIP P.A. FANS” signal at the

Data Logger is removed. J. A five minute counting period is reset which allows the primary air (P.A.) fans to

be started. K. A five second counting period is reset which will allow the “loss of fuel trip

arming” memory signal to be established when other permissives are satisfied (see “Oil Elevation Start” section for specifics).

L. All “cause of trip” memories are reset. M. The heavy oil trip valve can now be opened (see “Heavy Oil Trip Valve Operation”

section for specifics). HEAVY OIL TRIP VALVE OPERATION The heavy oil trip valve must be opened to heat the heavy oil before a furnace purge cycle is started and a “master fuel trip” exists (both (red) “MFT A TRIP and “ MFT B TRIP” light are on). This is accomplished by initially opening the heavy oil

KORBA SIMULATOR

157

recirculation valve (see “Oil Recirculation” section for specifics). When the heavy fuel oil recirculation valve is proven fully open, the heavy oil fuel trip valve can now be opened if all heavy oil nozzle valves remain closed (PURGE PERMITS (White) “NOZL VALVS CLOSED” light remains on). The heavy oil trip valve is energised to “open” when the H.O. TRIP VLV “ OPEN” push button is depressed. When the trip valve is moved from “closed” position, the (red) “OPEN” push button is illuminated. The trip valve is proven fully when the associated (green) “CLOSE” light goes off. The heavy oil is reciruclated so that the heavy fuel oil header temperature is satisfied. The heavy fuel oil supply pressure must also be satisfied. When these two conditions are satisfied, the heavy oil trip valve must be closed before a Furnace Purge can be started (see “Furnace purge” section, item 15c). When a “no master fuel trip” signal is established (both (green) “MFT A RESET” and “MFT B RESET” lights are on), the heavy oil trip valve can now be reopened if all of the following conditions are satisfied: 1. All heavy oil nozzle valves remain closed (PURGE PERMITS (White)”NOZL VALVS

CLOSED” light is on). 2. The heavy fuel oil header temperature remains satisfactory. 3. The heavy fuel oil supply pressure remains satisfactory. The heavy oil trip valve is energised to “Open” when the H.O. TRIP VALV “OPEN” push button is depressed. when the trip valve is moved from “closed” position, the (red) “OPEN” push button is illuminated and the (white) “PURGE READY” light goes off. The “elevation trip” signal at all four oil elevations (AB,CD,EF and GH) is removed and the “elevation start permit” is now “ armed”. The heavy fuel oil trip valve can be closed by depressing the H.O. TRIP VALVE “CLOSE” push button. The heavy fuel oil trip valve will be closed automatically if any of the following conditions exist : 4. Any heavy oil nozzle is not closed and a “master fuel trip” signal is established. 5. After any heavy fuel oil nozzle valve is not closed and any of the following

conditions exist for more than two seconds. A. The heavy fuel oil pressure is “low”, data logger receives a signal.

KORBA SIMULATOR

158

- OR -

B. The atomising steam pressure is “low”, data logger receives a signal.

- OR - C. The heavy fuel oil header temperature is “low-low”, data logger receives a signal. 6. Loss of critical power exists for more than two seconds. HEAVY OIL ELEVATION “AB” START (Typical for Elevations CD,EF & GH) All heavy oil elevations (AB,CD,EF & GH) are placed in service in the same manner. The “oil elevation start permit” must initially be established. The permit was “armed” when a “no master fuel trip” signal was established and the heavy fuel oil trip valve was proven fully open. The “oil elevation start permit” will now be established when the following condition is satisfied (see Note 4): 1. The air flow is greater than 30 % and less than 40%.

- AND - The nozzle tilts are horizontal. NOTE 4 When any feeder is “proven” (feeder is on for more than fifty seconds). item 1 above is no longer required to satisfy the “oil elevation start permit”. When the “oil elevation start permit” is established, the oil elevation can be placed in service in the “pairs” or “elevation” firing mode. The firing mode that is selected is automatically determined by the status of the feeders. The “pairs” firing mode is selected when all feeders are off for more than two seconds. The “elevation” firing mode is selected when any feeder is proven or an “auto start support ignition signal is established (see “Pulverizer Auto Start” section for specifics). The following sections describe the operation of these two different firing modes. Pairs Firing Mode Operation The “pairs” firing mode is automatically selected when all feeders are off for more than two seconds. Corners No. 1 and No. 3 are placed in service as one pairs. Corner No. 1

KORBA SIMULATOR

159

is placed in service initially and thirty second later Corner No. 2 is placed in service initially and thirty seconds later Corner2& No. 4 are placed in service as one pair. Either pair can be placed in service initially. We will assume that corner pair 1-3 is placed in service initially. Both pairs are placed in service in the same manner. After the “oil elevation start permit” signal is established, the “corner Pair” can be placed in service in the following manner: 1. Depress the PAIR 1-3 “START” push button (held depressed), the following events

occur: A. The pair 1-3 “start memory” signal is proven established when the (red) “START”

push button is illuminated and the associated (green)”STOP” light goes off. B. The “start corner No. 1” signal is established and the “start corner No. 3” signal is

“armed”. C. The auxiliary air dampers in the associated oil elevation are closed. D. The “elevation back-up trip” memory signal is removed. E. the “unsuccessful start” memory signal is removed, if it was established. F. A thirty second counting period is reset. G. A seventy second counting period is reset. 2. When the “START” push button is released, the following events occur: A. The thirty second counting period is started. B. The seventy second counting period is started. Each of the four oil elevation corners are placed in service in the same manner after “start corner” signal is established. The corner no. 1 oil gun is placed in service after the “start corner No. 1” signal is established (see item 1.B. above), if all of the following conditions are satisfied: 3 The associated oil gun is engaged. 4 The associated scavenge valve is closed. 5 The heavy fuel oil isolation valve is proven open-and- the atomising steam

isolation valve is open and the local control station the selector switch is proven in the REMOTE position when the LOCAL CONTROL STATION-COR. 1 (red) “REMOTE” light is on.

KORBA SIMULATOR

160

When these conditions (3 , 4 and 5) are satisfied simultaneously, an “advance oil gun” signal is established. The following events will now occur: 6 The associated high energy arc (HEA) ignitor “advance spark rod” signal is

established if the associated corner discriminating flame scanner proved “no flame” (DISC FLAME SCANNER COR 1 (GREEN) “NO FLAME” light is on and the associated (red) “FLAME” light is off). When the HEA ignitor is moved from the “retracted’ position, the HEA IGNITOR - COR 1 (yellow) “ADVD” light comes on. The HEA ignitor is proven advanced when the associated (green) “RETRD” light goes off. The steam atomising valves “open” command is now “armed”.

7 A “scavenge incomplete” memory signal is established which removed the “retract

oil gun” signal. 8 When the oil gun is moved from the retracted position, the following events occur: A. The OIL GUN COR 1 (red) “ADVD” light comes on. B. The “corner no. 1 shutdown” signal is removed. 9. The oil gun is proven “advanced” when the OIL GUN COR 1 (green) “RETRO” light

goes off. The following events will also occur : A. The HEA ignitors “spark” signal is now “armed”. B. The “corner trip” signal is removed, removing the heavy fuel oil nozzle valves

“close” command. C. The associated steam atomising valve’s “open” command is now established and

the “close” command is removed. The heavy fuel oil nozzle valve’s “open” command is now “armed”.

10. When the steam atomising valve is moved from the closed position, redundant

signals are established to ensure that the “retract oil gun” signal and “corner shutdown” signals remain removed.

11. When the steam atomising valve is opened, the following events will occur : A. The HEA ignitor “spark” signal is proven established when the HEA IGNITOR

COR 1 (red) “SPARK” light comes and (see item 9. A. above). B. The heavy fuel oil nozzle valve’s “open” command is now established (see item

9.C. above) 12. When the heavy fuel oil nozzle valve is moved from the “closed” position, the

following events occur: A. The OIL VLV COR 1 (red) “OPEN” light comes on.

KORBA SIMULATOR

161

B. When the first heavy oil nozzle valve is not closed, the heavy fuel oil trip valve is closed if the automising steam pressure is “low” or the header pressure is “low” or the oil temperature is “low-low” for more than two seconds.

C. A twenty five second counting period is started. 13. The heavy fuel oil nozzle valve is proven fully open when the OIL VALVE COR 1

(green) “CLSD” light goes off. 14. The corner oil gun proves flame when the DISC FLAME SCANNER COR 1 (red)

“FLAME” light comes on and the associated (green) “NO FLAME” light goes off. When the twenty five second counting period expires (see item 12.C above), the HEA ignitors “spark” signal is removed and the HEA ignitor is retracted.

15. If the corner oil gun does not prove flame when the twenty five second counting

period expires, the HEA ignitor’s “spark” signal is removed and the HEA ignitors “spark” signal is removed and the HEA ignitor is retracted and the heavy fuel oil nozzle valve is closed.

16. When the “heavy fuel oil flow satisfactory” signal is established and the heavy oil

nozzle valve remains fully open, the associated corner No. 1 oil gun is proven “in-service”.

When the thirty second counting period expires (see item 2.A. above), the “start corner No. 3” signal is established and the oil gun at corner No. 3 is placed in service in the same manner as the oil gun at corner No. 1 (starting with item 3 above). When the seventy second counting period expires (see item 2.B. above), a “corner trip’ signal is established if any of the following condition exist at the associated corner. 17. The corner oil gun does not prove flame. 18. The atomising steam valve is not open. 19. The heavy fuel oil nozzle valve is not fully open. Corner pair 2-4 are placed in service in the same manner as corner pair 1-3. When at least three of the four oil guns are “in-service” (heavy fuel oil nozzle valve is fully open a fuel flow is adequate at the associated oil nozzle valve), a “H.F.O. elevation in service” signal established. This is proven when the PULV START PERMITS (white) “IGNITION PERMIT” lights comes on at both adjacent coal elevations. When the seventy second counting period expires for either corner pair (1-3 or 2-4), the Data Logger’s “UNSUCCESSFUL SPARK ROD RETRACTION” signal is established if any HEA ignitor spark rod is not retracted on the associated oil elevations. The auxiliary air dampers “close” command is removed and the auxiliary air dampers on the associated oil elevation are positioned for “oil firing” when any of the following conditions occur:

KORBA SIMULATOR

162

20. Any heavy fuel oil valve is not closed on the associated oil elevation

AND The “ elevation start” memory signal does not exist for both pairs (1-3 and 2-4).

OR The seventy second counting period expires for both pairs (1-3 and 2-4).

OR At least three of the four oil nozzle valves are proven fully open and fuel flow is adequate the associated oil nozzle valve. Elevation Firing Mode Operation The “elevation” firing mode operation is automatically selected when any feeder is “proven” or “auto start support ignition” signal is established (see “Pulverizer Auto Start” section for specifics). After the “oil elevation start permit” signal is established, the associated oil elevation is placed in service when the PAIR 1-3 or the PAIR 2-4 “START” push button is depressed and then released. The oil corner pair 1-3 are placed in service in the same manner as previously described in the “Pair Firing Mode Operation” starting with item 1 thru item 16. When the thirty second counting period expires, the “start corner No. 3” signal is established and the oil gun at corner No. 3 is placed in service in the same manner as the oil gun at corner No. 1. When the “start corner No. 3” signal is established, a thirty second counting period is started. Thirty seconds later, the pair 2-4 “ started “ memory signal is established. This is indicated by the PAIR 4 (red) “START” light coming on and the associated (green) “STOP” light going off. The second pair (2-4) are now placed in service in the same manner as pair 1-3. Corner No. 2 will be placed in service and then corner No. 4 will be placed in service after a delay of thirty seconds. When both seventy second “elevation pair” counting periods expire, the Data Logger will received “UNSUCCESSFUL START” signal for the associated oil elevation if a “HFO elevation in service” signal is not established for more than two seconds. A “ HFO elevation in service” signal does not exist when less than three of the four oil nozzle valves or the associated oil nozzle valve indicating “inadequate” fuel flow.

KORBA SIMULATOR

163

PULVERIZER OPERATION All coal elevation ( A thru H) are placed in service in the same manner. The pulverizers can be placed in service manually or automatically. Both procedures are described in the following sections. Pulverizer ignition Permissives Prior to starting any pulverizer, the pulverizer ignition energy must be adequate to light off coal. The Pulverizer ignition energy is adequate (to support coal firing) for the coal elevation that is selected when the conditions listed below are satisfied. Pulverize “A” : 1. An “elevation AB H.F.O. elevation in service” signal is extablished. NOTE 5 A “ HFO elevation in service” signal is established when at least three of the four oil nozzle valves are proven fully open and fuel flow is adequate at the associated oil nozzle valve.

OR 2. Elevation B feeder is “proven” (feeder is on for more than fifty seconds) and the

associated feeder speed is operating at greater than 50 % and the boiler load is greater than 30 %.

Pulverizer “B” : 1. An “elevation AB H.F.O. elevation in service” signal is established (see Note 5).

OR 2. Elevation A or C feeder is “proven” and the associated feeder speed is operating at

greater than 50% and the boiler load is greater than 30%. Pulverizer “C” : 1. An “elevation CD H.F.O. elevation in service” signal is established (see Note 5).

OR 2. Elevation B or D feeder is “proven” and the associated feeder speed is operating at

greater than 50% and the boiler load is greater than 30 %. Pulverizer “D” :

KORBA SIMULATOR

164

1. An “elevation CD H.F.O. elevation in service” signal is established (see Note 5).

OR 2. Elevation C or E feeder is “proven” and the associated feeder speed is operating at

greater than 50 % and the boiler load is greater than 30 %. Pulverizer “E” : 1. An “elevation EF H.F.O. elevation in service” signal is established (see Note 5).

OR 2. An “elevation CD H.F.O. elevation in service” signal is established (see Note 5)

and the elevation D feeder is proven and the associated feeder speed is operating at greater than 50 %.

OR 3. Elevation D or F feeder is “proven” and the associated feeder speed is operating at

greater than 50% and the boiler load is greater than 30 %. Pulverizer “F” : 1. An “elevation EF H.F.O. elevation in service” signal is established (see Note 5).

OR 2. Elevation E or G feeder is “proven” and the associated feeder speed is operating at

greater than 50 % and the boiler load is greater than 30 %. Pulverizer “G” : 1. An “elevation GH H.F.O. elevation in service” signal is established (see Note 5).

OR 2. An “elevation EF H.F.O. elevation in service” signal is established (see Note 5) and

the elevation F feeder is proven and the associated feeder speed is operating at greater than 50 %.

OR

3. Elevation F or H feeder is “proven” and the associated feeder speed is operating at

greater than 50 % and the boiler load is greater than 30 %. Pulverizer “H” :

KORBA SIMULATOR

165

1. An “elevation GH H.F.O. elevation in service” signal is established (see Note 5).

OR 2. Elevation G feeder is “proven” and the associated feeder speed is operating at

greater than 50 % and the boiler load is greater than 30 %. The “pulverizer ignition permit” is proven established when the PULV START PERMITS (white) “IGNITION PERMIT” light comes on. The pulverizer on the associated coal elevation can now be placed in service after other permissives are satisfied. Pulverizer Ready Prior to starting a pulverizer, a “Pulverizer Ready” signal for the selected pulverizer must be established. This signal is established when all of the following conditions are satisfied: 1. A “Pulverizer start permit” signal must be established. This signal is initially

established when the following conditions are satisfied. A. The air flow is greater than 30 % and less than 40%. B. The nozzle tilts are horizontal. C. A “no master fuel trip” memory signal remains established. The pulverizer start

permit” signal is proven established when the PULV START PERMITS (white) “START PERMIT” light is on.

After any feeder is proven, items A & B above are no longer required to satisfy the “pulverizer start permit”. 2. The “primary air permit” signal is satisfied. There are two separate “pulverizer primary air permit” signals. One signal is used for pulverizers A,B,C and D. The other signal is used for pulverizers E,F,G and H. The “primary air permit” signal (for pulverizers A,B,C and D) is established when the following conditions are satisfied : A. Both F.D. fan is on and both P.A. fans are on

OR At least one F.D. fan is on and at least one P.A fan is on and less than four pulverizers are on B. The hot primary air duct pressure (for pulverizers A,B, C,D) is “not low”

KORBA SIMULATOR

166

AND C. The hot primary air duct pressure (for pulverizers A,B,C,D) is “not low-low”. The “primary air permit” signal (for pulverizers E,F,G,H) is established when the following conditions are satisfied: D. Same as “A” above

AND E. The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low”

AND F. The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low-low”.

The “primary air permit” signal is proven established when the ‘PULV START PERMITS (white) “P.A. PERMIT” light comes on. After the associated pulverizer is on, the “primary air permit” is no longer required at pulverizer that is on.

3. The pulverizer discharge valve must be opened. This is accomplished by

depressing the DISCH VLV “OPEN” push button. When the discharge valve is moved from the closed position, the (red) “ OPEN” push button is illuminated. The discharge valve is proven open when the associated (green) “CLOSE” light goes off and the PULV START PERMITS (white) “DISCH VLV OP” light comes on.

4. The pulverizer outlet temperature is proven less than 2000 F when the PULV start

permits (white) “ OUTLET < 2000 F light comes on. 5. At the pulverizer hydraulic journal system, the hydraulic pump control is placed

in the REMOTE and AUTO positions. When this condition is satisfied, the PULV START PERMITS (white) “ JRNL CTRL PERMIT” light comes on.

6. The feeder controller is proven in the REMOTE position when the PULV START

PERMITS (white) “FDR IN REMOTE “ light is on. 7. The cold air gate is proven open when the PULV START PERMITS (white) “COLD

AIR GATE OP” light is on. 8 The tramp iron hopper valve is proven open when the PULV START PERMITS

(white) “TRAMP IRON VLV OP” light is on. 9. The feeder inlet gate is proven open when the PULV START PERMITS (white)

“FDR INLET GATE OP” light is on. 10. A “ no automatic pulverizer unsuccessful start” memory signal is proven

established when the PULV START PERMITS (white) “ NO UNSUC. START” light is on. This signal is established because the associated pulverizer if off.

KORBA SIMULATOR

167

11. The PULV START PERMITS (white) “LUB PRESS SATIS” light comes on when the

pulverizer’s lube oil pressure has remained “not low” for more than five minutes. 12. The PULV START PERMITS (white) “SATIS LUB LVL & TEMP” light comes on

when the lube oil sump level is adequate and the lube oil temperature is greater than 320C. After the pulverizer is on, this permissive is not required to keep the “pulverizer ready” signal established at the pulverizer that is on.

13. A “pulverizer trip” signal does not exist when PULV START PERMITS (white) “NO

PULV TRIP” light is on (see “Pulverizer in Service” section for specifics). After item’s 1 thru 13 above are satisfied, the PULV START PERMITS (white) “PULV READY” light comes on. This indicates that the pulverizer an now be placed in service if the “pulverizer ignition permit” remains satisfied (PULV START PERMITS (white) “IGNITION PERMIT” light is on). The pulverizer can now be placed in service manually or automatically as described in the following sections. MANUAL START The associated pulverizer can be placed in service manually after the PULV START PERMITS (white) “IGNITION PERMIT” and “PULV. READY” light are on. The pulverizer is placed in the manual mode of operation by depressing the PULV MODE “MANUAL” push button momentarily. The “manual mode” memory signal is proven established when the (green) “MANUAL” push button is illuminated and the associated (red) “AUTO” light is off. The pulverizer can now be placed in service manually in the following manner: 1 Momentarily depressing the PULV “START” push button will establish a

“pulverizer start” memory signal (see Note 6). Note 6 A “pulverizer start” memory signal is also established if a “auto start pulverizer” signal is established“ . The following events will now occur: A. The “pulverizer start” signal is now “armed”. B. The pulverizer seal air valve’s “close” command is removed and the “open

command is established. The seal air valve is proven open when the SEAL AIR VLV (red) “OPENED” light is on and the associated (green) “CLOSED” light is off.

C. The pulverizer hydraulic journal system’s hydraulic pump is placed in service.

The pump is proven on when the JOURNAL PUMP (red) “ON” light is on and the associated (green) “OFF” light goes off.

KORBA SIMULATOR

168

D. A ten second counting period is started. 2. After the pulverizer seal air valve is opened and the seal air header to pulverizer

underbowl differential pressure is proven greater than 8 inches w.c., the PULV START PERMITS (white) “SEAL AIR PRESS SAT.” light comes on. When this light comes on, the “pulverizer start” signal is established (see item 1.A. above).

3. When the pulverizer is on, it establishes a “pulverizer on” memory signal. The

following events will now occur. A. The PULV (red) “START” push button is now illuminated and the associated

(green) “STOP” light goes off. B. The ten second counting period is reset (see item 1.D. above). If the pulverizer is

not on when this ten second counting period expires, the pulverizer is tripped. C. The pulverizer discharge valve cannot be closed. D. The pulverizer seal air valve cannot be closed. E. The associated auxiliary air dampers cannot be closed. F. The hot air gate can now be opened. G. The feeder can now be started. H. The cold air dampers are opened to the “100% pulverizer air flow position” and

the “run cold air dampers to < 5% open” signal is removed. I. The “close hot air damper” signal is removed. J. If the pulverizer lube oil pump is off, the Data Logger receives a “PULV LUBE OIL

PRESS. LOW” signal. If this signal remains for more than ten seconds, the pulverizer is tripped.

K. If the pulverizer air header to pulverizer underbowl differential pressure is less

than 5 inch w.c., the Data Logger receives a “PULVERIZER SEAL AIR DP LOW” signal. If this signal remains for more than ten minute, the pulverizer is tripped.

L. The pulverizer hydraulic journal system is now affected in the following manner. a. The Data Logger receives a “PULV JOURNAL HYDRAULIC LEVEL LOW” signal, if

the hydraulic fluid level is low.

KORBA SIMULATOR

169

b. The pressure control system is activated. c. A 120 second counting period is started. d. When the journal hydraulic pressure is satisfactory, the associated feeder can be

started. e. When the 120 second counting period expires, the Data Logger receives a “PULV.

JOURNAL HYDRAULIC PRESSURE LOW” signal if the pressure is low. The associated feeder cannot be placed in service. Corrective action must be taken.

4. After the pulverizer is proven on, the hot air gate should now be opened to

establish the desired coal/air temperature at the pulverizer outlet. The hot air gate will receive an “open” command after the HOT AIR GATE “OPEN” push button is depressed (see Note 7 ). NOTE 7 The hot air gate will also receive an “open” command automatically (after the pulverizer is on), if a “auto open hot air gate” signal is established. See Pulverizer Operation Auto Start” section. The following events will now occur : A. When the hot air gate is moved from the closed position, the (red) “OPEN” push

button is illuminated. The “ open cold air damper to 100 % pulverizer air flow position” signal is now removed.

B. The hot air gate is proven open when the associated (green) “CLOSE” light goes

off. The pulverizer temperature control will now receive a “release air and temperature control to AUTO” signal.

5. It should be noted that the feeder can be placed in service in the MANUAL MODE

of operation without opening the hot air gate. 6. The feeder can now be placed in service, if the following conditions remain

satisfied: A. “Pulverizer ignition permit” remains satisfied. B. The associated pulverizer remains on. C. The journal hydraulic pressure remains satisfied. D. A “no master fuel trip “memory signal remains established.

KORBA SIMULATOR

170

E. The “pulverizer ready” signal remains established. F. The pulverizer outlet temperature is greater than 130 F. G. The “feeder speed demand at minimum” signal is established because the feeder

is off. The feeder can now be placed in service. 7. The feeder is now placed in service when the FEEDER “START” push button is

held depressed. The following events will occur. A. The one hundred eighty “ignition permit required” counting period is reset. B. The five second “coal flow” counting period is started. C. If the feeder discharge chute is not plugged, the feeder “start” signal is

established. The feeder is proven on when the (red) “START” push button is illuminated and the associated (green) “STOP” light goes off. The “feeder seal in “ signal is now established and the “START” push button can be released (after it is illuminated). When the push button is realised the 180 second counting period is started (see item A above).

8. When the five second counting period expires (see item 7.B. above), the following

events can occur : A. The Data Logger receives a “NO COAL FLOW” signal if the “coal on belt” signal

does not exist. B. The feeder is tripped automatically if the following conditions exists. a. The “coal on belt” signal does not exist

AND b. The pulverizer motor power is “low” 9. After the feeder is proven on, the following events occur : A. A fifteen second counting period is started. B. A fifty second counting period is started.

KORBA SIMULATOR

171

C. A “feeder on” memory signal is established, the following events occur: a. The “run feeder speed demand to minimum” signal is now removed if

pulverizer motor power “not high” and the pulverizer bowl differential pressure is “not high”.

b. A three minute counting period is reset. c. A five second counting period is reset. 10. If the feeder goes off after it was on, the five second counting period is started (see

item 9.C.c. above). The following events will occur which will minimize the possibility of a pulverizer fire, if the hot air gate is not closed.

A. The hot air dampers are closed. B. The cold air dampers are opened to the “ 100% pulverizer air flow” position. C. The pulverizer temperature control’s air and temperature control is removed from

AUTO. D. A thirty second counting period is started. Thirty seconds later, the hot air gate

is closed. E. When the hot air gate is closed, the hot air dampers “close” signal is removed if

the pulverizer outlet temperature remains less than 2000F. The cold air dampers will remain in the “100 % pulverizer air flow “position.

11. When the fifteen second counting period expires (see item 9.A. above), the

“include feeder in totalizing circuit” signal is established. 12. When the fifty second counting period expires (see item 9.B. above), a “feeder

proven” memory signal is established and the following events occur: A. The “release feeder speed to auto” signal is now established because the “run

feeder speed demand to minimum” signal was previously removed (see item 9.C.a. above).

B. If at least two of the four scanner indicate flame on the associated flame scanner

elevation, the FIREBALL FLAME SCANNERS (red) “ELEV FLAME” light is on and the associated (green) “ELEV NO FLAME “ light is off.

KORBA SIMULATOR

172

C. When the feeder speed is increased above 50 %., a permissive is established which can established a “pulverizer ignition permit” signal (see “Pulverizer Ignition Permissives” section for specifics).

When the 180 second counting period expires (see item 7.C. above), this indicates that the feeder is established and the furnace flame has stabilized. The “Pulverizer ignition energy” that was initially required to support coal firing is no longer required (see “Pulverizer Ignition Permissives” section for specifics) and can now be removed. It is recommended that a minimum of two feeders be established at greater than 50% loading before the ignition support energy is removed (see “Operator Note” below). OPERATOR NOTE A signal feeder in service for more than fifty seconds at its minimum speed on approximately 25 % constitutes a “Fireball Established”. A signal “Fireball” results when an elevation is in service. Additional elevations placed in service merely enlarges this single “Fireball”. The established “Fireball” is monitored by the associated flame scanners. Only in an emergency situation would an operator select and start an elevation remote from one that is already in service. In this case, good operator procedure dictates that the second feeder be placed in service and “pulverizer ignition energy” be maintain unit both feeders are loaded to greater than 50 % before ignition energy is removed. When removing feeders from service, the inverse procedure should be followed. The “pulverizer ignition energy” should be reinstated when only two feeders are in service and operating at less than 50 % loading. Auto Start The associated pulverizer can be placed in service automatically after the PULV START PERMITS (white) “IGNITION PERMIT” and “PULV READY” lights are on. The pulverizer is placed in the automatic mode of operation by depressing the PULV MODE “AUTO” push button momentarily. The “auto mode” memory signal is proven established when the (red) “AUTO” push button is illuminated and the associated (green) “MANUAL” light is off. The pulverizer can now be placed in service automatically in the following manner : 1. Momentarily depress the PULV “START” push button, the following events will

occur: A. A 210 second” elevation start” counting period is reset and then started.

KORBA SIMULATOR

173

B. The “auto start” memory signal is established. C. An “auto start support ignition” signal is established at the associated oil

elevation. The oil elevation is placed in service in the same manner as previously described in the “Elevation Fire mode Operation” section, if the “oil elevation start permit” signal is established.

2. When the “pulverizer ignition permit” signal is established (PULV START

PERMITS (white) “IGNITION PERMIT” light is on) at the coal elevation being placed in service and both seventy second counting periods have expired, an “auto start pulverizer” and a “auto open hot air gate” signals are established. A sixty second counting period is now “armed”.

3. The “auto start pulverizer” signal will now place the pulverizer in service in the

same manner as previously described in the “Pulverizer Operation Manual Start” section starting with item 1 (see Note 6).

4. After the pulverizer is proven on, the “auto open hot air gate” signal will open the

hot air gate in the same manner as previously described in the “Pulverizer Operation Manual Start’ section, starting with item 4 (see Note 7)

5. When the Pulverizer is on, the sixty second counting period is now started (see

item 2 above when the sixty second counting period expires, an “auto start feeder’ signal is established for five seconds.

6. After the hot air gate is proven open (HOT AIR GATE (green) “CLOSE” light is off)

AND the “auto start feeder” signal is established, the following events will occur : A. The one hundred eighty “ignition permit required” counting period is reset. B. The five second “coal flow” counting period is started. C. If the feeder discharge chute is not plugged, the feeder “start” signal is

established. The feeder is proven on when the FEEDER (red) “START” light is on and the associated (green) “STOP” light is off. The “feeder seal in” signal is now established. If the “feeder seal in signal is not established when the “auto start feeder” signal is removed (after five seconds), the feeder is tripped.

7. The feeder is placed in service in the same manner as previously described in the

“Pulverizer operation - Manual Start” section, starting with item 8. If this signal exists, the following events will also occur: 8. The air and temperature control is removed from AUTO.

KORBA SIMULATOR

174

9. The hot air dampers are closed. 10. The cold air dampers are opened to the “100 % pulverizer air flow” position. 11. The hot air gate is closed after a delay of thirty seconds. 12. When the feeder is off for more than three minutes, the associated pulverizer is

stopped. Pulverizer in Service During normal operation as the unit load increases and decreases, the individual pulverizers share the load. When the average loading with pulverizers in service exceeds 80 %, an additional pulverizer should be placed in service. When the average loading with the pulverizers in service is reduced to less than 40 %, a pulverizer should be taken out of service. When pulverizer and associated feeder are in service, they are subject to the following operational checks : 1. Any of the following conditions will run the feeder speed to minimum until the

initiating condition is corrected: A. Pulverizer bowl differential pressure high. B. Pulverizer motor power high. 2. Five seconds after the “feeder start” command is established, “no coal on belt”

and “pulverizer power less than min. “will trip the feeder. The Operator should take appropriate corrective action, then restart the feeder. If the hydraulic oil pressure is inadequate, the feeder will be tripped.

3. A high pulverizer outlet temperature (above 200 F) will close the hot air gates and

open the cold air dampers to the “100 % pulverizer air flow” position after the air and temp. control are released form auto control.

The high temperature signal will then close the hot air gate after a time delay of thirty seconds. (see Caution Note).

CAUTION A HIGH PULVERIZER OUTLET TEMPERATURE ON AN OPERATING PULVERIZER COULD BE INDICATION OF A PULVERIZER FIRE.. 4. Any of the following condition will cause an individual pulverizer to trip: A. Elevation power or Unit power is lost for more than two seconds. B. Any pulverizer discharge valve not open.

KORBA SIMULATOR

175

C. Pulverizer on and seal air underbowl differential pressure is low (< 5" W.C.) for

more than sixty seconds D. Pulverizer lube oil pressure is not on and associated pulverizer is on for more

than ten seconds. E. Pulverizer lube oil pressure is “not adequate” and pulverizer is on for more than

ten seconds. F. Pulverizer ignition energy not available when support ignition is required (before

expiration of the three minute ignition time period). G. A “primary air trip” signal exists (see Note 8) NOTE 8 A “primary air trip” exists when the following conditions exists at the elevations listed below: Elevations A,B,C,D: 1. Any pulverizer is on AND All F.D. fans are off or all P.A. fans are off OR 2. For Pulverizer A,B,C,D, the hot primary air duct pressure is “Low - Low” OR 3. For Pulverizer A, B, C, D, the hot primary air duct pressure is “low” for more than

five seconds. Elevations E,F,G,H: 4. Same as item 1 above OR 5. For Pulverizer E,F,G,H, the hot primary air duct pressure is “Low - Low” OR

KORBA SIMULATOR

176

6. For Pulverizer E,F,G,H the hot primary air duct pressure is “low” for more than five seconds.

If at least five pulverizers are on and less than two F.D. fans are on or less than two P.A. fans are on, the following events occur:

7. Pulverizer “H” is tripped immediately, then at two second intervals pulverizer G,F

and E are tripped. After pulverizer “H” is tripped, the pulverizers will only be tripped until four pulverizers remain in service. The “primary air trip” signal is then removed. More than four pulverizers can only be placed in service when both F.D. and both P.A. fans are on.

A “pulverizer trip” signal is proven established when the PULV START PERMITS (white) “NO PULV TRIP” light goes off.

UNIT SHUTDOWN When the unit is shutdown, the pulverizers should be removed from service and then the oil elevation are shutdown. PULVERIZER SHUTDOWN The pulverizers can be removed from service in the “manual” or “automatic” mode of operation. The loading should be reduced and then the pulverizer is shutdown. All coal elevations (“A” thru “H”) are removed from service in the same manner. The following sections describe both shutdown procedures. Manual Shutdown When the pulverizer is in the auto mode of operation (PULV MODE (green)”MANUAL” light is on and the associated (red) “AUTO” light is off), the pulverizer on the associated coal elevation is removed from service in the following manner: 1. If the associated oil elevation is not in service, start the oil elevation. 2. Reduce the feeder speed to minimum. This will automatically remove the feeder

speed from AUTO control. 3. Close the hot air gate by depressing the associated HOT AIR GATE “CLOSE” push

button. The hot air dampers are closed, the air and temperature control is removed from AUTO control and cold air dampers are opened to the “100 % pulverizer air flow” position. Thirty seconds later, the hot air gate “close” command is established.

When the hot air gate is moved from the fully open position the HOT AIR GATE (green) “CLOSE” light comes on. The hot air gate is proven closed when the associated (red) “OPEN” light goes off.

KORBA SIMULATOR

177

4. When the pulverizer outlet temperature is reduced below 130 F, shut down the

feeder by depressing the FEEDER “STOP” push button. The following events will now occur:

A. The “start feeder” signal is removed and two seconds later the “feeder seal in”

signal is removed. B. The feeder is proven off when the (green) “STOP’ push button is illuminated and

the associated (red) “START” light is off. C. The “feeder off” memory signal is established and the “feeder proven” memory

signal is removed. D. The fifteen second counting period is reset which removes the “include feeder in

totalizing circuit” signal. E. The fifty second “feeder proven” counting period is reset. F. A fifty second counting period is started. Fifty seconds later, the associated

elevation of fuel air dampers are closed. 5. Allow the pulverizer to run until it is completely empty of coal, then shut down

the pulverizer by depressing the associated PULV “STOP” push button. The pulverizer is proven off when the associated (green) “STOP” push button is illuminated and the associated (red) “START” light is off. The pulverizer seal air valve is closed, the pulverizer hydraulic journal system’s hydraulic pump is shutdown and the pulverizer discharge valve can now be closed, if it is deemed necessary.

6. The pulverizer discharge valve should be left open to allow air flow to exist

through the pulverizer when it is not in operation. 7. The associated oil elevation is shutdown once furnace conditions have stabilized

(see “Oil Elevation Shutdown” section for specifics). Auto Shutdown When the pulverizer is in the auto mode of operation (PULV MODE (red) “AUTO” light is on and the associated (green) “MANUAL” light is off), the pulverizer on the associated coal elevation is removed from service in the following manner: 1. Depressing the PULV “STOP” push button momentarily will cause the following

events to occur simultaneously:

KORBA SIMULATOR

178

A. The “auto start” memory signal is removed. B. The “auto stop” memory signal is established. C. A ten minute “elevation stop” counting period is reset and then started. D. An “auto start support ignition” signal is established and the associated oil

elevation is placed in service in the “elevation firing mode”. 2. When the “pulverizer ignition permit” signal for the associated coal elevation is

established (PULV START PERMITS (white) “IGNITION PERMIT” light is on) AND both seventy second counting periods have expired, the following events occur:

A. A “run feeder speed demand to minimum “ signal is established which removes

the feeder speed control from AUTO and reduces the feeder speed to minimum. B. A “auto close hot air gate” signal is established, causing the following events to

occur: a. The hot air dampers are closed. b. The air and temperature control are released from AUTO control. c. The cold air dampers are opened to the “100 % pulverizer air flow” position. d. A thirty second counting period is started. Thirty seconds later, the hot air gate

is closed. 3. When the hot air gate is proven closed (HOT AIR GATE (red) “OPEN” light is off)

AND the pulverizer outlet temperature is less than 130 F , an “ auto stop feeder signal is established.

4. The feeder is now shutdown in the same manner as previously described in the

“Manual shutdown” section , item 4. 5. When the feeder is off, a three minute counting period is started. Three minutes

later, a “auto stop pulverizer” signal is established. 6. The pulverizer is now shutdown in the same manner as previously described in

the “Manual Shutdown” section, item 5. 7. When the ten minute counting period expires (see item 1.C. above). The Data

Logger will receive a “UNSUCCESSFUL AUTO PULVE SHUTDOWN” signal if the following conditions are satisfied.

A. The hot are gate is not closed OR

KORBA SIMULATOR

179

B. The feeder is on OR C The pulverizer is on. 8. The pulverizer discharge valve can now be closed, if it is deemed necessary. The

pulverizer discharge valve should be left open to allow air flow to exist through the pulverizer when it is not in operation.

9. The associated oil elevation is shutdown once furnace conditions have stabilized. OIL ELEVATION SHUTDOWN All oil elevation (AB, CD,EF,GH) are shutdown in the same manner. The oil elevations can only be shutdown manually. The oil elevation can be shutdown if the “elevation” firing mode exists or if the “pair” firing mode exists. The shutdown procedure for both firing modes is described in the following sections. “Pair” Firing Mode Shutdowns If all feeders are off for more than two seconds, the “pairs firing mode is automatically selected. When “pairs” firing mode is selected, either pair (1-3 or 2-4) can be initially removed from services. Both pairs are shutdown in the same manner. Initially, it is assumed that pair 1-3 will be shutdown. This pair is shutdown in the following manner: 1. Momentarily depress the PAIR 1-3 “STOP” push button, the following events will

occur simultaneously: A. The “pair stop” memory signal is proven established when the (green) “STOP”

push button is illuminated and the associated (red) “START” light is off. B. A thirty second counting period is reset and then started. C. A 340 second counting period is reset and then started. D. The “stop corner No. 1” signal is established. E. The “stop corner No. 3” signal is “armed”. 2. Corner No. 1 is shutdown in the following manner after “stop corner No. 1” signal

is established. A. The heavy fuel oil nozzle valve at corner No. 1 receives “close: command.

KORBA SIMULATOR

180

B. When the oil nozzle valve is moved from the fully open position, the OIL VALVE COR 1(green) “CLSD” light comes on. The oil nozzle valve is proven closed when the associated (red) “OPEN” light goes off.

3. When the oil nozzle valve is proven closed, the steam scavenge valve receives an

“open” command and the steam automizing valve receives a redundant “open” command (atomizing valve is open). The HEA ignitor “spark rod” receives an “advance” signal for fifteen seconds.

4. When the HEA spark rod is moved from the retracted position, the HEA IGNITOR

COR 1 (yellow) “ADVD” light comes on. The HEA spark rod is proven advanced when the associated (green) “RETRO” light goes off. The spark rod is now energized. When the fifteen second counting period expires, the “spark” is extinguished and the spark rod is retracted.

5. The steam scavenge valve is proven fully open when the OIL VALVE COR 1

(white) “SCAV” light comes on. A five minute counting period is now started. 6. When the five minute counting period expires, a “scavenge complete” memory

signal is established. This signal causes the following events to occur: A. The (white) “SCAV” light goes off and the steam scavenge valve is closed. B. A “corner trip” signal is now established because the associated corner

discriminating flame scanner indicates “no flame” (DISCR FLAME SCANNER COR 1 (green) “NO FLAME” light is on and the associated (red) “FLAME” light is off).

7. The “corner trip” signal sends redundant “close” signals to the heavy fuel oil

nozzle valve and the steam scavenge valve to reinsure that they are closed. A “close” command is now established at the steam atomizing valve.

8. When the steam atomizing valve is closed, the oil gun receives a “retract” signal. 9. When the oil gun is moved from the advanced position, the OIL GUN COR 1

(green) “RETRD” light comes on and a redundant “ corner trip” signal is established to ensure that the fuel oil, steam atomizing and scavenge valves are closed.

10. The oil gun is proven retracted when the associated (red) “ADVD” light goes off.

The “scavenge incomplete” memory signal is now reestablished and a “corner shutdown” signal is now established for corner No. 1. The oil gun at corner no. 1 is now successfully shutdown. When the thirty second counting period expires (see item 1.B. above) , the “stop corner No. 3” signal is now established which was previously “armed” (see item 1. E. above).

Corner No. 3 oil gun is now shutdown in the same manner as previously described for the oil gun at corner No. 1 starting with item 2 above.

KORBA SIMULATOR

181

When corner No. 1 and No. 3 were shutdown and the 340 seconds counting period expires (see item 1.C. above), the “elevation stopped and time expired” signal is “armed”.

The second corner pair (2-4) are removed from service in the same manner as corner pair (1-3) when the PAIR 2-4 “STOP” push button is momentarily depressed. The oil gun at corner No 2 is removed from service and thirty seconds later corner No, 4 is removed from service in the same manner as previously described for corner No. 1.

When the 340 seconds counting period for corners 2-4 is also expired, the “elevation stopped and time expired” signal that was previously “armed” is now established.

The following events will now occur: 11. The Data logger receives a “UNSUCCESSFUL FUEL OIL ELEV. SHUTDOWN”

signal if the corner shutdown” signal was not established at any of the four corners (see item 10 above).

12. The Data Logger receives a “UNSUCCESSFUL SPARK ROD RETRACTION” signal

if any of the four corner HEA ignitor spark rods were not retracted (HEA IGNITOR COR (yellow) “ADVD” light is on).

13. An “elevation back up trip” memory signal is now established which establishes

redundant “corner trip” signals at all four corners on the associated oil elevation. The auxiliary air dampers on the associated oil elevation can now be closed if other permissives are satisfied.

“Elevation” Firing Mode Shutdown If any feeder is “proven” the “elevation” firing mode is automatically selected. If any feeder remains “proven” when the oil elevation is removed from service, the associated oil elevation is removed form service in the following manner: 1. Depressing the pair 1-3 or the PAIR 2-4 “STOP” push button momentarily will

cause the following events to occur: A. Corner pair 1-3 are removed from service in the same manner as previously

described in the “Pair. Firing Mode Shutdown” section, starting with item 1 and through item 10.

B. When the “stop corner no. 3” signal is established, corner no. 3 is removed from

service and simultaneously a thirty second counting period is started.

KORBA SIMULATOR

182

C. When the thirty second counting period expires, a corner pair 2-4 “stop” signal is established. Corner No. 2 is then removed from service and then corner No. 4 is removed from service after a delay of thirty seconds.

All four corners are removed from service in the same manner as previously described in the “Pair Firing Mode Shutdown” section.

CORNER SHUTDOWN Any corner oil gun can be removed from service at the corner local control station. IF the associated corner atomizing steam isolation valve remains open, a “stop corner” signal can be established when the selector switch at the local control station is placed in the “SCAVENGE” position. This is indicated by the LOCAL CONTROL STATION COR (white) “SCAV” light coming on. The “stop corner” signal is now established and the associated corner oil gun is removed from service in the same manner as previously described in the “Pair Firing Mode Shutdown” section starting with item 2. If the local control station selector switch is placed in the “OFF” position, the LOCAL CONTROL STATION COR (green) “OFF” light comes on. A “corner trip” signal is established and the oil gun is shutdown without scavenging. The oil gun must then be retracted by another procedure. BOILER TRIP A “boiler trip’ command stops all fuel inputs by tripping all of the pulverizers and feeders and closing all heavy oil nozzle valves on all elevations. There are two separate “boiler trip” commands in this unit. Both “no boiler trip” command signals must be established before a furnace purge cycle can be initiated. A “boiler trip” command will establish a “master fuel trip” memory signal. This is indicated by the (red) “ MFT TRIP” light being on and the (green) “MFT RESET” light being off. When a “master fuel trip” memory signals established (red, “MFT TRIP” light is on), the following events occur: 1. The (red) “MFT A TRIP” and MFT B TRIP” lights come on and the associated

(green) “MFTA RESET” and “MFT B RESET” lights go off. 2. The Data Logger receives a “MFT A TRIPPED” AND MFT B TRIPPED” SIGNALS. 3. The “boiler load greater than 30 %” memory signal is removed.

When the “master fuel trip” memory signal is established (red, “MFT A TRIP” or MFT B TRIP” LIGHT IS ON), the following events occur:

KORBA SIMULATOR

183

4. Both of the (red ) “BOILER TRIP” light come on and the “PUSH TO PURGE” AND “PURGING” light are “armed”.

5. The PULV MODE (green) “MANUAL” light comes on, if it was off. 6. All pulverizers are tripped as indicated by the PULV START PERMITS (white) “NO

PULV TRIP” lights going off. 7. A five minute counting period is started. Five minutes latter, all cold air dampers

are opened to the “100 % pulverizer air flow position”. 8. The “permit to start P.A. fans” signal is removed. 9. The “oil elevation trip” memory signal is established at all oil elevations. 10. If all heavy fuel oil nozzle valves are not closed, the heavy fuel oil trip valve is

closed. The heavy fuel oil trip valve can then be reopened after all heavy fuel oil nozzle valves are closed and the heavy fuel oil recirculation valve is opened.

11. A five second counting period is started. Five seconds later, the “loss of fuel trip

arming” signal is removed. 12. The CAUSE OF TRIP memories cannot be reset. 13. All feeders are shutdown. 14. The upper and lower fuel air dampers are opened. 15. The auxiliary air control is transferred to MANUAL control and all auxiliary air

dampers are opened. 16. The primary air (P.A.) fans are tripped. 17. The “feed forward to furnace draft control” signal is established for thirty seconds

if the following conditions are satisfied: A. The unit critical power is available for more than six seconds AND B. The “loss of fuel trip arming” signal is established. When this signal is established, item “B” is no longer required to keep this signal established. Thirty seconds later, the “feed forward to furnace draft control” signal is removed. 18. The furnace pressure recorder changes to a higher speed for thirty seconds.

KORBA SIMULATOR

184

When the thirty second counting period expires, the furnace pressure recorderwill remain at the higher speed if a “high furnace pressure alarm” or a “low furnace pressure alarm” signal is established. When both of these signals do not exist for more than thirty seconds, the furnace pressure recorder reverts to its original speed. The recorder will revert to the higher speed if either of these signals are reestablished.

A “boiler trip signal is established if any of the following conditions exist: 19. Loss of ACS power for more than two seconds. 20 Loss of customer’s 220 VDC Battery power for more than 2 ) seconds. 21. Loss of unit critical power for more than two seconds. 22. A “simulator trip” signal exists. 23. The water drum level is “low” for more than ten seconds. 24. The water drum level is high” for more than ten seconds. 25 All boiler feed pumps are off. 26. “Inadequate waterwall circulation” signal exists. 27. All I.D. (Induced Draft) fans are off. 28. ALL F.D. (Forced Draft) fans are off. 29. The air flow is less than 30 % before the boiler load exceeds 30 %. 30. The deaerator level is “low-low”. 31. At least two of the three pressure switches indicate a “high furnace pressure trip”

condition. 32. At least two of the three pressure switches indicate a “low furnace pressure trip”

condition. 33. Both BOILER TRIP (emergency) push buttons are depressed simultaneously. 34. All feeders are off and loss of power exists at the elevation that is in service. 35. A loss of reheat protection occurs. 36 A “loss of fuel trip” signal is established (see Note 9).

KORBA SIMULATOR

185

NOTE 9 The “loss of fuel trip” signal becomes “armed” when the first oil elevation that is placed in service has at least three of the four heavy oil nozzle valves proven fully open (OIL VALVE COR (green) “CLOSED” lights are off). After the “loss of fuel trip” signal is “armed”, a “loss of fuel trip” signal will be established if all of the following conditions occur simultaneously: A. At all coal elevation, the feeder is off or loss of elevation power exists. This

condition exists for more than two seconds AND

At all four oil elevations all oil nozzle valves are closed or an “elevation trip” signal is established at the associated oil elevation.

The “loss of fuel trip” signal is proven established when the Data Logger receives a “LOSS OF ALL FUEL TRIP” signal.

B. At all coal elevations, the feeder is off or loss of elevation power exists. This

condition exists for more than two seconds. AND The heavy fuel oil trip valve is not fully open AND At all four oil elevations, all oil nozzle valves are closed.

When the “master fuel trip” memory signal exists for more than five seconds the “loss of fuel trip arming” memory signal is removed.

The Data Logger’s “LOSS OF ALL FUEL TRIP” signal will remain established if item B above is satisfied. When the heavy oil trip valve is proven fully open (for oil recalculation), this signal is removed.

37. A “unit flame failure” signal is established (see Note 10). NOTE 10 During light off and before any feeder is “proven” for more than two seconds, the “fireball” flame scanners do not take part in the overall flame failure protection systems. When any feeder is “proven” for more than two seconds, the system automatically changes from flame failure protection of an individual fuel nozzle to a

KORBA SIMULATOR

186

“FIREBALL” supervision of the furnace. The system is designed to initiate a “boiler trip” when any feeder is “proven for more than two seconds and all five fireball flame scanner elevations vote “no flame” simultaneously. After any feeder is “proven” for more than two seconds, the UNIT FLAME FAILURE (amber) “ARMED” light comes on. After this light is on, a “unit flame failure “signal is established when all five UNIT FLAME FAILURE (amber) “GH” and “FG” and “DF” and “BC” and “AB” lights are all on simultaneously. This is indicated when the Data Logger receives a “FLAME FAILURE TRIP” signal. This signal causes a “master fuel trip” memory signal to be established (both (red) “BOILER TRIP” lights come on). When each fireball flame scanner elevation votes “no flame”, the associated UNIT FLAME FAILURE (amber) light comes on at the associated fireball flame scanner elevation. Listed below are the conditions that will cause this (amber)light to be illuminated for the various fireball flame scanner elevations. Elevation “AB”: 1. Feeder A is off or loss of elevation A power and Feeder B is off or loss of elevation

B power. This condition exists for more than two seconds. OR 2. At elevation AB, less than three of the four heavy fuel oil nozzle valves are fully

open or fuel flow is not adequate at the associated oil nozzle valve or elevation AB power is not available for more than two seconds and less than two of the four “fireball” flame scanners indicate flame on elevation “AB”

OR 3. At elevation AB, less than three of the four heavy fuel oil nozzle valves are fully

open or fuel flow is not adequate at the associated oil nozzle valve or elevation AB power is not available for more than two seconds and any elevation AB heavy fuel oil nozzle valve is not closed or elevation AB power is not available for more than 2 seconds.

Elevation “BC”: 1. Feeder B is off or loss of elevation B power and Feeder C is off or loss of elevation

C power. This condition exists for more than two seconds. 2. Less than two of the four “fireball” flame scanners indicate flame on elevation

“BC”.

KORBA SIMULATOR

187

Elevation “DE”: 1. Feeder D is off or loss of elevation D power and Feeder E is off or loss of elevation

E power. This condition exists for more than two seconds. 2. Less than two of the four “fireball” flame scanners indicate flame on elevation

“DE”. Elevation “FG”: 1. Feeder F is off or loss of elevation F power and Feeder G is off or loss of elevation

G power. This condition exists for more than two seconds. 2. Less than two of the four “fireball” flame scanners indicate flame on elevation

“FG”. 3. One elevation GH, any heavy fuel oil nozzle valve is not closed or elevation GH

power is not available for more than two seconds. Elevation “GH”: 1. Feeder G is off or loss of elevation G power and Feeder H is off or loss of elevation

H power. This condition exists for more than two seconds. OR 2. At elevation GH, less than three of the four heavy fuel oil nozzle valves are fully

open or fuel flow is not adequate at the associated oil nozzle valve or elevation GH power is not available for more than two seconds and less than two of the four “fireball” flame scanners indicate flame on elevation “GH”

OR 3. At elevation GH, less than three of the four heavy fuel oil nozzle valves are fully

open or fuel flow is not adequate at the associated oil nozzle valve or elevation GH power is not available for more than two seconds and any elevation GH heavy fuel oil nozzle valve is not closed or elevation GH power is not available for more than 2 seconds.

CAUSE OF TRIP SYSTEM A “Cause of Trip” system has been incorporated which allows the Operator to determine the cause of a master fuel trip which was initiated by a boiler trip command.

KORBA SIMULATOR

188

The boiler trip commands that can cause a “master fuel trip” memory signal to be established . The first boiler trip command that causes a master fuel trip (both (red) “BOILER TRIP” lights come on), will illuminate the appropriate indicator in the CAUSE OF TRIP section on the console insert. The Data Logger will also receive a corresponding signal. Any successive boiler trip commands to the other indicators are blocked. There will be only one indicator that is illuminated. When the furnace purge cycle is successfully completed (PURGE CYCLE (yellow) “PURGE COMPLETE” light is on) and a “ no master fuel trip” memory signal is established (both (red) “BOILER TRIP” lights are off), all CAUSE OF TRIP memories are reset and there are no illuminated indicators. POST PURGE EXCURSION PROTECTION A post purge excursion circuit has been designed into the Furnace Safeguard Supervisory System. It operates as described below: 1. During the Furnace Purge Cycle, the following conditions are satisfied: A. The mode permit is satisfied B. All heavy fuel oil nozzle valves are closed C. The heavy fuel oil trip valve is closed, D. All pulverizers are off E. All feeders are off F. All flame scanners (discriminating and fireball) indicate no flame G. Air flow is greater than 30 % 2. When all of these conditions are satisfied simultaneously, a five minute counting

period is started. After the five minute counting period expires, the following events will occur:

A. A “post purge time expired” memory signal is established and a “post purge fan

trip” signal is established if a “high or low furnace pressure trip” signal is established.

This is indicated when the Data Logger receives a “FURNACE PRESSURE HIGH” or a “FURNACE PRESSURE LOW” signal.

KORBA SIMULATOR

189

The “post purge fan trip” signal is proven established if the Data Logger receives “POST PURGE FAN TRIP” signal. If this signal is established, the I.D. and F.D. fans are tripped.

B. The “open upper fuel air dampers” memory signal is removed, closing the upper

fuel air dampers. Simultaneously, a thirty second counting period is started.

When the thirty second counting period expires, the “open lower fuel air dampers” memory signal is removed, closing the lower fuel air dampers. Simultaneously, a five second counting period is started.

When the five second counting period expires, the auxiliary air dampers are now released from manual to the auxiliary air control system and the “open auxiliary air dampers” signal is removed. When all auxiliary air dampers are modulating, item 12 in the “Furnace Purge” section is satisfied.

When any heavy fuel oil elevation has at least three of the four oil nozzle valves fully open, the “post purge time expired” memory signal is removed which will now prevent the “post purge fan trip” signal from being established. When the heavy oil trip valve is moved form the closed position (for oil recalculation), the five minute counting period is reset.

PRIMARY, SCANNER AND SEAL AIR FAN OPERATION The operation of the various air fan control systems are described in the following sections. PRIMARY AIR FAN CONTROL There are two primary air fans serving the unit. The primary air fans are used primarily to transport the pulverized coal to the respective coal nozzles at each coal elevation. When a “master fuel trip” memory signal is established, the primary air fans are tripped. When the “master fuel trip” signal exists for more than five minutes, all cold air dampers are opened to the “ 100% pulverizer air flow position”. When the furnace purge cycle is successfully completed and a “no master fuel trip’ signal is established (both (red) “BOILER TRIP” lights are off), the primary air fans can be placed in service. This is accomplished when the customer supplies a “any primary air fan start command”. When this signal is established, the “open cold air dampers to 100% pulverizer airflow position” memory signal is removed and all cold air dampers on all coal elevations (“A” thru “H”) are positioned to “less than 5 % open” because the associated pulverizers are off. When all elevation coal air dampers are positioned to “less than 5 % open”, the “permit to start P.A. fans” signal is established.

KORBA SIMULATOR

190

The primary air fan can now be placed service. After a primary fan is on, a signal is established which keeps the “permit to start P.A. fans” signal established. The “cold air dampers opened to less than 5 %” is no longer required. The second primary air fan can now be placed in service, when it is required. A “primary air permit” signal is required before a pulverizer can be started. There are two separate “pulverizer primary air permit” signals. One signal is used for pulverizers A, B, C, D. The other signal is used for pulverizers E,F,G,H. The “primary air permit” signal (for pulverizers A,B,C and D) is established when the following conditions are satisfied: 1. Both F.D. fans are on and both P.A. fans are on OR

At least one F.D. fan is on and at least one P.A. fan is on and less than four pulverizers are on

AND 2. The hot primary air duct pressure (for pulverizers A,B,C,D) is “not low” AND 3. The hot primary air duct pressure (for pulverizers A,B,C,D) is “not Low-Low”

The “primary air permit” signal (for pulverizers E,F,G,H) is established when the following conditions are satisfied:

4. Same as “1” above AND 5. The hot primary air duct pressure (for pulverizers E,F,G,H) is “not low” AND 6. The hot primary air duct pressure (for pulverizers E,F,G,H)is “not Low- Low”

The “primary air permit” signal is proven established when the PULV START PERMITS (white) “P.A. PERMIT” light comes on. After the associated pulverizer is

KORBA SIMULATOR

191

on, the “primary air permit” signal is no longer required at the pulverizer that is on.

A “primary air trip” signal will trip any pulverizer that is in service (PULV START PERMITS (White) “NO PULV TRIP” light goes off). A “primary air trip” signal is established at pulverizers A,B,C and D when the following condition exists:

7. Any purlveriser is on AND All P.A. fans are off or all F.D. fans are off OR 8. For pulverizers A,B,C, D:

The hot primary air duct pressure is “low” for more than five seconds or the hot primary air duct pressure is “low-low”.

A “primary air trip” signal is established at pulverizers E,F,G AND H when the following conditions exists:

9. Same as item 7 above OR 10. For pulverizers E,F,G,H:

The hot primary air duct pressure is “low” for more than five seconds or the hot primary air duct pressure is “low-low”.

If a “primary air trip” signal is established at pulverizers E,F,G, and H, the pulverizers are removed form service in the following manner:

11. If at least five pulverizers are on and less than two F.D. fans are on or less than

two P.A. fans are on, the following events will occur: A. Pulverizer “H” is tripped immediately; then at two second intervals, pulverizers

G,F and E are tripped. B. After pulverizer “H” is tripped, the pulverizers will only be tripped until four

remain in service. The “primary air trip” signal for pulverizers E,F,G,H is now removed.

KORBA SIMULATOR

192

C. More than four pulverizers can only be placed in service when both F.D. and both P.A. fans are on. When this is acco,plished, the “primary air permit” sigfnal is reestablished and the remaining pulverizers can then be placed in service.

The Data Logger will receive signals when any of the following conditions exist: 12. Hot primary duct pressure is “low” for pulverizers A,B,C,D. 13. Hot primary duct pressure is “low” for pulverizers E,F,G,H. 14. Both P.A. fans are off and any pulverizer is on. SCANNER AIR FAN CONTROL The are two (2) scanner air fans service the unit. The scanner air fans can be placed in service manually or automatically. Both procedures are described in the following sections. When both F.D. fans are off, the scanner air emergency dampers are opened. The dampers are proven open when the SCANNER AIR (red) “EMERG DAMPR OP” light is on and the assocaited (green) “EMERG DMPR CL” light is off. When a least one F.D. fan is not off (“on”), the scanner air emergency dampers are closed. Manual Operation Either scanner air fan can be placed in service manually in the following manner: 1. Momentarily depress the SCANNER AN A or the SCANNER FAN B “START FAN”

push button. The following events occur: 2. A “scanner start” memory signal is established. The associated scanner air fan

recieves a “start” command. Simultaneously, a two second counting period is started if both scanner fans are off.

3. The associated scanner air fan motor is started. The scanner air fan is proven on

when the SCANNER FAN (red) “START FAN” push button is illuminated. The associate (green) “STOP FAN” light goes off. The following events will also occur:

A. The associated scanner air fan outlet damper receives an “open” command. The

scanner fan outlet damper is proven open when the (red) “FAN OUTLET DAMPER OPEN” light comes on.

B. A five second counting period is started if the other scanner air fan is off. Five

seconds later, the associated scanner air fan’s outlet damper receives a “close” command and is closed. The outlet damper is proven closed when the associated (red) “FAN OUTLET DAMPER OPEN” light goes off.

4. If bothscanner air fans remain off when the two second counting period expires

(see item 2 above), the “LOSS OF EITHER SCANNER FAN” signal at the Data

KORBA SIMULATOR

193

logger is established. If this signal is established, both scanner air fans ( A and B) receive “start” commands and are placed in service simultaneously.

Either scanner air fan can be removed from service manually if the scanner duct to furnace differential pressure is greater than 6 inches w.g. This is accomplished in the following manner.

5. Momentarily depress the SCANNER FAN “STOP FAN” push button. The following

events will occur: A. The “scanner start” memory signal is removed. This removes the scanner air fans

“start” command. B. The scanner air fan is proven off when the (green) “STOP FAN” push button is

illuminated and the associated (red) “START FAN” light is off. C. If the other scanner air fan is on, the scanner air fan outlet damper at the

scanner air fan that stopped will be closed after a delay of five seconds. D. If the other scanner air fan is off, the scanner air fan outlet damper at the

scanner air fan that was stopped will remain open even though the “open” command was removed.

Automatic Operation The scanner air fans will be placed in service automatically if the scanner duct to furnace differential pressure is less than six inches w.g. (see note 11). NOTE 11 If the scanner duct to furnace differential pressure remains at less than six inches w.g. for more than ten seconds, the Data Logger receives a “LOSS OF SCANNER COOLING AIR “ signal. The scanner air fans are placed in service in the following manner: 1. Scanner air fan “A” “scanner start” memory signal is established and scanner air

fan “A” is placed in serivice in the same manner as previously described in the “Manual Operation “section, starting with item 2. Simultaneously, a five second counting period is started.

2. When the five second counting period expires, scanner air fan “B” is placed in the

same manner as previously described in the “Manual Operation” section, starting with item 2.

If loss of unit critical power exists for more than two seconds, both scanner air fans ( A and B) are started and both scanner air fan outlet dampers are opened simultaneously.

KORBA SIMULATOR

194

The scanner air fans are removed from service in the following manner: 3. The “scanner start” memory signal at scanner for “B” is removed and a ten

second counting period is started. 4. “Scanner air fan “B” is removed from service in the same manner as previously

described in the “Manual Operation” section, starting with item 5. 5. When the ten second counting period expires (see item 3 above) the “scanner

start” memory signal at scanner fan “A” is removed if the scanner duct to furnace differential pressure remains greater than 24 inches w.g. Scanner air fan “ A” is removed from service in the same manner as previously described in the “Manual Operation” section, starting with item 5.

SEAL AIR FAN CONTROL There are four seal air fans that serve the unit. Two seal air fans are used for pulverizers A,B,C,D and the other two seal air fans are used for pulverizers E,F,G,H. Both pair of seal air fans are placed in service and removed from service in the same manner. Seal air fans No. 1 and No. 2 are used with pulverizers A,B,C,D. Seal Air fans No. 3 and No. 4 are used with pulverizers E,F,G,H. The air fans can be placed in service and removed from service manually or automatically. Both procedures are described in the following sections. The operation of seal air fans No. 1 and No. 2 will only be described. Seal air fans No. 3 and No. 4 operation is indentical. Manual Operation Either seal air fan can be placed in service manually in the following manner: 1. Momentarily depress the SEAL AIR FAN No.1 or the SEAL AIR FAN No. 2 push

button. The following events occur: 2. A “seal start” memory segnal is established. The associated seal air fan receives

a “start” command. Simultaneously, a two second counting period is started if both seal air fans (No. 1 and No. 2) are off.

KORBA SIMULATOR

195

3. The associated seal air fan motor is started. The seal air fan is proven on when the SEAL AIR FAN NO. (red) “START FAN” push button is illuminated. The associated (green) “STOP FAN” light goes off. The following events will also occur:

A. The associated seal air fan discharge damper receives an “open” command. The

seal air fan discharge damper is proven open when the associated (green) “FAN OUTLET DMPR CL” . light is off. The associated (red) “FAN OUTLET DMPR OP” light came on when the discharge damper was not closed.

4. If both seal air fans remain off when the two second counting period expires (see

item 2 above), the “SEAL AIR FAN 1 & 2 OFF > 2 SEC” signal at Data logger is established. If this signal is established, both seal air fans (No. 1 and No. 2) receive “start” commands and are placed in service simultaneously.

If both seal air fans are on (No. 1 and No. 2) , only one of the seal air fans can be stopped. This is accomplished in the following amnner:

5. Momentarily depress the SEAL AIR FAN NO. “STOP FAN” push button. The

following events will occur: A. The “seal start” memory signal is removed and the “seal stop” memory signal is

established. B. The seal air fan is proven off when the (green) “STOP FAN” push button is

illuminated and the associated (red) “START FAN” light goes off. C. The associated seal air fan discharge damper is closed. Automatic Operation The seal air fans will be placed in service automatically in the following amnner: 1. When either P.A. fan is on, a two “start” command is established and a “seal

start” memory signal is established at seal air fan No. 1 and seal air fan No. 1 is placed in service in the same manner as previously described in the “Manual Operation” section, starting with item 2.

2. When either P.A. fan is on and if the seal air header to cold air duct differential

pressure is less than four inches w.g. (pulverizers A,B,C,D) for more than ten seconds, the Data logger recieves a “SEAL AIR HEADER/COLD AIR DUCT P LOW > 10 SEC (PULV’S A,B,C,D)” signal and a “seal start” memory signal is established at seal air fan No. 2.

Seal air fan No. 2 is then placed in service in the same manner as previously described in the “Manual Operation” section. starting with item 2.

KORBA SIMULATOR

196

The seal air fans are removed from service automatically when both P.A. fans are off more than fifteen seconds. When the seal air fan is off, the associated seal air fan discharge damper is closed. PULVERIZER LUBE OIL PUMP OPERATION Each coal elevation’s pulverizer has an associated lube oil pump system. The pulverizer lube oil pump must be operating properly before the associated pulverizer can be placed in service. Initially, the lube oil tempreture must be greater than 32 C and the lube oil sump level must be adequate. When this condition is satisfied, the PULV START PERMITS (white) “STATIS LUBE LVL & TEMP” light comes on (See “Pulverizer Ready “section, item 12). If the lube oil sump level is not adequate for more then ten secondsm the date Logger receives a “PULV LUBE OIL LELVEL LOW > 10 SEC.” signal. If the lube oil temperature is “low”, the Data Logger receives a “PULV LUBE OIL TEMP. LOW” signal. The lube oil pump is proven on when the LUBE PUMP (red) “ON” light is on and the associated (green) “OFF” light is off. When the lube oil pressure is “not low” for more than five minutes, the PULV START PERMITS (white) “LUBE PRESS SATIS” light comes on (See “Pulverizer Ready” section, item 11). After other permissive are also satisfied, the pulverizer can be placed in service. When the pulverizer is on, the “lube oil temperature greater than 32 C” and “lube oil sump level adequate” requirements are no longer required to satisfy the “pulverizer ready” permissive. When the pulverizer is on, the pulverizer will be tripped after a delay of ten seconds if the lube oil pump is off, When the pulverizer lube oil pump is on and the lube oil pressure is “low” the Data Logger recieves a “PULV LUBE OIL PRESS LOW” signal. If this signal exists for more than ten seconds, the pulverizer is tripped. SECONDARY AIR CONTROL For a complete and detailed description of the secondary air damper controls, refer to the manufacturer’s instructions. Operation of auxiliary and fuel air dampers as affectedby the Furnance Safeguard Supervisory System are described below. AUXILIARY AIR DAMPERS All elevations of auxiliary air dampers are transferred to manual control and are opened when any of the following events occur: 1. All I.D. or F.D. fans are off. 2. A “master fuel trip” memory signal is established.

KORBA SIMULATOR

197

3. Loss of unit critical power for more than two seconds exists.

When the five minute “post purge” counting period expires (see “Post Purge Excursion Protection” section for specifics), a thirty second counting period is started. When the thirty second counting period expires, a five second counting period is started. Five seconds later, the auxiliary air control is removed from “MANUAL” operation and the “open auxiliary air dampers” command is removed. The auxiliary air control can now be placed in “AUTO” conrol.

After the auxiliary air control is in “AUTO” contol and at least one I.D. fans is on and at least one F.D. fan is on, all elevation of auxiliary air dampers modulate to maintain a pre-determined set point differential pressure between the windbox and furnace. This is indicated by the DAMPERS MODE (red) lights coming on. When all nine elevations are modulating, the PURGE PERMITS (white) “AUX AIR DMPRS MOD” light comes on. this condition exists during the furnace purge cycle and initial operation of the unit up to 30 % loading.

The auxiliary air dampers on a heavy fuel oil elevation are closed for a high energy arc (HEA) oil start when the following conditions are satisfied:

1. The boiler load is less than 30 % AND 2. An “elevation start” memory signal is established and both seventy second

“elevation pair” counting periods have not expired and less than three of the four oil nozzle valves are fully open or oil flow is not adequate at the associated oil nozzle valve.

The auxiliary air dampers on a heavy fuel oil elevation are positioned to the “warm up firing” position when the following conditions are satisfied:

3. At least one corner oil nozzle valve on the associated oil elevation is not closed AND 4. At least three of the four oil nozzle valves are fully open and oil flow is adequate

at the associated oil nozzle valve or both seventy second “elevation pair” counting periods have expired.

When the unit loading exceeds 30 %, the differential set point is gradually increased to a higher set point as the boiler loading is increased. The rate of

KORBA SIMULATOR

198

increase (“slope”) of the differential pressure is controlled by the Auxiliary Damper Control.

Simultaneously (above 30 % loading), the auxiliary air dampers on elevations “HH”, “FG” , “DE”, “BC” and “AA” close in a timed sequence (ten second intervals), if the pulverizers on adjacent elevations are off. The auxiliary air dampers on elevations “GH”, “EF”, “CD” and “AB” close in time sequence (ten second intervals), if the pulverizers on adjacent elevations are off and a “heavy fuel oil elevation back up trip” signal is established on the associated elevation. The “close” commands are initially sent to the upper elevation not in service and progressing to the lowest elevation.

When the until load is reduced below 30 %, the auxiliary air dampers open in a timed sequence (ten second intervals), starting with the lowest elevation of auxiliary air dampers. Simultaneously, the differntial set point reverts to its lower setting.

FUEL AIR DAMPERS 1. All I.D. or F.D. fans are off. 2. A “master fuel trip” memory signal is established. 3. Loss of unit critical power for more than two seconds exists.

When the five minute “post purge” counting period expires (see “Post Purge Excursion Protection” section for specifics), the upper fuel air dampers “open” command is removed which closes the upper fuel air dampers. Simultaneously, a thirty second counting period is started. Thirty seconds later, the lower fuel air dampers “Open” command is removed which closes the lower fuel air dampers.

When the feeder is “proven” (feeder is on for more than 50 seconds), the feeder speed is released AUTO control and the fuel air dampers modulates as a function of feeder speed. This is indicated by the DAMPERS MODE (red) light coming on at the associated coal elevation. The associated CL (green) light will be off.

When a feeder is off for more than fifty seconds, the associated elevation of fuel air dampers are closed.

KORBA SIMULATOR

199

PROTECTION AND INTERLOCKS

KORBA SIMULATOR

200

KORBA SIMULATOR

201

PROTECTION AND INTERLOCKS ID FANS INTERLOCKS ID FAN - A START PERMISSIVES 1. Inlet Guide Vane Position minimum. 2. Hyd. coupling scoop position minimum. 3. SAPH A / B Running and Inlet / Outlet dampers open & any FD discharge damper open (SAD 1 / 2). 4. Hyd. coupling oil Pump ON and pr. adequate. > 1.2 Kg / cm2 5. Inlet / Outlet dampers fully closed. 6. Hyd. coupling oil level normal. 7. Hyd. coupling oil temp. at cooler inlet normal. < 95 0C 8. Hyd. coupling oil temp. at cooler outlet normal. < 65 0C 9. Temp. of Motor , Fan & 8 H.C. bearings are normal. <80 oC 10. ID Fan - B is not running in Bus ‘A’ 2. TRIP CONDITION 1. Any hyd. coupling temp very high > 85 0C 2. Hyd. coupling oil temp at cooler inlet very high. >100 0C 3. Hyd. coupling oil temp at cooler outlet very high. > 75 0C 4. Fan/motor bearing temp. Hi - Hi > 85 0C 5. Hyd. coupling oil pressure lo - lo < 0.5 Kg/cm2 6. Discharge dampers / gate does not open fully within specified time. 3 min after

the fan start 7. Post purge furnace pressure hi/lo from FSSS 8. ID - A trips when both FD fans are running & FD Fan A trips

KORBA SIMULATOR

202

9. Electrical Protection Trip 10. Emergency PB Pressed ID FAN - B (BUS - B) START PERMISSIVES 1. Same as ID Fan - A for 1 to 9 2. ID Fan C not running and ID Fan B not running on BUS - A TRIP CONDITIONS 1. Same as ID - A for 1 to 7 2. ID Fan B (BUS-B) trips when both FD fans are running and FD Fan B trips. ID FAN - B (BUS-A) START PERMISSIVES : 1. Same as ID Fan A for 1 to 9 2. ID Fan A not running and ID Fan B not running on BUS - B TRIP CONDITIONS 1. Same as ID Fan A for 1 to 10 2. ID Fan B (BUS - A) trips when both FD fans are running and FD Fan A trips. ID FAN - C : START PERMISSIVES 1. Same as ID Fan A for 1 to10 2. ID Fan B not running on Bus - B. TRIP CONDITIONS 1. Same as ID Fan A for 1 to 7

KORBA SIMULATOR

203

2. ID Fan C trips when both FD fans are running and FD Fan B trips. HYDROCOUPLING OIL PUMP INTERLOCKS The Pump Selected To Lead starts under the following conditions : 1. When the ID fan start command is given the pump starts and runs for 40 secs. 2. The pump starts if the oil pr. is less than specified limit < 1.8 Kg/cm2 3. The pump starts and runs for 25 mins after the ID fan stops The Pump Selected To Lead stops under the following Conditions : 1. Stops after 40 Secs of ID fan start command and oil pr. reaches the specified

limit. > 2.2 Kg / cm2 [NB The pump selected to lag starts when lead pump fails to start.] FD FAN-A START PERMISSIVE 1. Blade pitch position min 2. Control oil pressure adequate > 8 Kg / cm2 3. Lub 0il presssur adequate > 0.5 Kg/cm2 4. Any ID fan running AND no FD fan running - OR - Two ID fans running 5. Discharge damper fully closed. TRIP CONDITIONS 1. No ID fan is running 2. Fan / motor bearing temp. Hi-Hi > 85 0 C 3. Discharge damper does not open fully within specified time after 2 min starting fan 4. Post Purge furnace Pr. Hi / Lo from FSSS

KORBA SIMULATOR

204

5. FD fan B running, ID fanB running on BUS B & running ID fan A trips FD FAN - B START PERMISSIVES 1. Same as FD - A TRIP CONDITIONS 1. Same as ID - A for 1 to 7 2. FD - A running and ID - A running, ID-B running on BUS - B trips. F.D.Fan oil pump interlocks When the selector switch is in Auto, the oil pump starts under the following conditions. 1. LEAD pump starts when FD fan start command is given. 2. Fan running and control oil pr. is < 6 Kg / cm2 3. When the LEAD pump trips, LAG pump starts within 1 sec. PA FAN - A START PERMISSIVES : 1. F.D. fan A or B running but PA fan B not running or both FD fan A & B running. 2. Lub / Control oil pressure adequate. > 8 Kg / cm2 3. Blade pitch position minimum 4. Outlet damper fully closed. 5. Start permit from FSSS (Purge cycle complete & MFR reset. TRIP CONDITIONS 1. Fan / motor bearing temp Hi-Hi > 85 0 C 2. Discharge damper does not fully open within 100 Secs. 3. Trip from FSSS (MFT) 4. Both PA - A & B running, on FD - A trip PA - A trip

KORBA SIMULATOR

205

5. Electrical Protection trip 6. Emergency PB pressed PA FAN - B START PERMISSIVES : 1. F.D. fan A or B running but PA fan A not running or both FD fan A & B running. 2. Others same as PA fan A TRIP CONDITIONS 1. Same as PA fan A for 1 to6 2. Both PA fan A & B running, on FD fan B trip PA fan B trip PA fan oil pump interlocks : When the selector switch is in Auto the oil pump starts under the following conditions. 1. Pump selected to LEAD pump starts when fan start command is given. 2. Stand by ( LAG ) pump starts when fan is running and control <6 Kg/cm2 oil

pressure is low. 3. LAG pump starts when fan is running and LEAD pump trips. B.C.W. PUMP INTERLOCKS START PERMISSIVES: 1. Both the discharge valves 1 & 2 fully open. 2. Motor cooling water flow adequate >32 GPM 3. Motor cavity temp. not High < 57.2oC 4. Pump cavity suction manifold diff. temp adequate. < 37.8 0 C TRIP CONDITIONS 1. Any of the discharge valves not fully open. 2. Motor cavity temp. high for more than 5 sec. 57.2 O C 3. Electrical protection trip / EPB pressed AUTO START Pump selected auto starts when

KORBA SIMULATOR

206

1. Any running pump tripsand 2 secs not over. 2. Boiler load > 60 % & only 1 pump is effective (i.e. second pumps not running &

DP low ( < 10 Psi ) AIR HEATERS ELECTRIC / AIR MOTOR DRIVE INTERLOCK (PAPH & SAPHS) START PERMISSIVE FOR ELECTRIC MOTOR 1. Both hand switches of SB Lop are not OFF 2. Both hand switches of GB Lop are not OFF 3. Air Motor Hand Switch on Auto 4. Air preheater receiver air pr. Adequate START PERMISSIVE FOR AIR MOTOR 1. Start Hand switch of Electric motor should not in off position. 2. Air motor starts when electric motor trips. G.B. AND S.B. LOP OF AIR HEATERS : STARTS WHEN : 1. Oil temp > 550C, lead pump starts. 2. Lag pump starts if the lead pump is OFF and Oil temp > 550C 3. Running Oil pump will stop when oil temp. falls below 450C CAUSES OF BOILER TRIP Boiler trips if any of the following happens. 1. Loss of 220 V D.C. Power Supply > 2 Secs. 2. Loss of unit critical power supply > 2 Secs. (Unit critical power consists of unit logic Voltage and unit critical interrogate scan Voltage, which scans All MFT I / P Contracts) 3. A ‘Simulator Trip’ signal exists (All oil & coal elevations OR Unit not in operate

mode) 4. Drum level is Lo - Lo. for 10 Secs

KORBA SIMULATOR

207

5. Drum level is Hi-Hi. for 10 Secs 6. All BFP OFF 7. “Inadequate water wall circulation” signal exists.

( i.e. if Boiler Load is > 60 % and atleast two B.C.W. Pumps are ineffective (Pump is ‘ON & its DP between suction & discharge is < 10 psi 5 Sec OR Pump is OFF)

OR

Boiler load is < 60 % AND (No B.C.W. Pump is ON OR Pump ON AND DP is low) 8. All ID fans are off 9. All FD fans are off 10. Air flow is less than 30 % of rated air flow, before the Boiler load exceeds 30 % <

624 T / hr 11. The deaerator level is Lo-Lo (2/3 logic, Two from< - 2134 mm 12. 2 out of 3 Furnace Pressure Hi-Hi <+ 325 mmWC 13. 2 out of 3 Furnace Pressure Lo - Lo < - 250 mmWC 14. Manual emergency Trip (Both the push buttons are pressed ) 15. All feeders OFF AND LOSS of Power exists at any oil elevation that is in sevice. 16. Loss of Reheat Protection > 5 Sec. a) Boiler working but all HP ESVs OR all IP ESVs are closed AND (both the HPBP

valves closes or both the LPBP valves closes)

- OR - b) Boiler working AND (Generator ckt. br. opened or turbine tripped) AND (Both

HPBP valves are closed (open < 2 %) or both LPBP valves are closed (Open < 2 %). 17. “A loss of fuel trip “Signal is established (This signal is established under the

following condition)

After loss of fuel trip signal is “armed” (i.e. when any oil elevation that is placed in services has atleast 3 / 4 HONVS proven open for > 2 Secs.) this signal will be established if.

A) All feeders OFF or Loss of elevation. Power in all coal elevation > 2 Secs AND (All

HONVS closed at all four oil elevations or any elevation trip signal is established at the elevation in services.

KORBA SIMULATOR

208

OR

B) (All feeders OFF or Loss of elevation. Power > 2 Secs.

AND HOTV valve not fully open

AND All 4 oil elevations HONVS are closed. 18. A “Unit flame failure “ siganl is established (This trip is “armed” only if a feeder is proven for > 2 Secs. This trip is established when unit flame failure is armed AND All elevations scanner Vote ‘NO FLAME’ simultaneously) INTERLOCKS FOR COAL ELEVATIONS MILL DISCHARGE VALVE (MDV) Does not accept stop command if Pulv is ‘ON’ MILL INTERLOCKS : (A) START PERMISSIVES : Mill starts after the ‘ON’ push button is pressed if following conditions are fulfilled 1. Pulveriser Ready is available. This signal will be available if following conditions

are fulfilled a) M.D.V. is open (all four) b) Mill outlet temp < 93 0 C c) Feeder local switch in Remote d) Pulv. start permit (if Nozzle tilt Horizontal & air flow < 40 % ) OR ( Any feeder proven and NO MFT ) e) Cold air gate open f) Tramp iron valve open g) Feeder inlet gate open h) Lub oil level & temp. adequate i) Lub oil pressure not low for more than 300 sec

KORBA SIMULATOR

209

j) No Mill trip existing k) P.A. permit available (i.e. (i) Hot P.A. duct Pressure. not low ( > 625 mm wc) (ii) P.A. duct pr. not lo-lo ( > 500 mmWc AND

(iii) Both FD s ON and both PA fans ‘ON’ or (Any PA fan ON and any FD Fan ‘ON’ and > 4 mills not ON)

AND

2. No Auto pulv unsuccessful start 3. Seal air Header to mill under bowl DP satisfactory > 8" wc 4. Mill not ‘ON’ 5. Pulv Ignition permit available.

For Mill A: a ) AB elevation 3/4 HONV’s open

OR b) Boiler load > 30 % and Feeder - B speed > 50 % ( > 30 T/hr.) For Mill B: a) AB elevation proven

OR b) Boiler load > 30 % and Feeder A or Feeder C proven. For Mill C: a) CD elevation proven

OR b) AB oil elevation and feeder B proven

OR c) Boiler load > 30 % & either feeder B or Feeder D proven.

KORBA SIMULATOR

210

For Mill D : a) CD elevation proven

OR b) Boiler load > 30 % and either feeder C or feeder E proven. For Mill E,F,G & H identical logic. Mill TRIPS / STOPS: a) Auto / manual mode selected to manual & stop PB depressed.

OR b) Pulv. start command given & not ‘ON’ for > 2 Secs.

OR c) Loss of Elevation poer OR Unit critical power for >2 Secs

OR d) Pulv ‘ON’ & seal air / under DP Low < 5” wc for more than 1 minute.

OR e) Pulv ‘ON’ and lub oil pump OFF > 10 sec. f) Pulv ‘ON’ and lub oil pr. low > 10 secs. < 1.76 Kg/cm2 g) Ignition permit required (> 180 secs) & ignition permit lost (i.e. with -in 180 sec of

feeder start) h) Any of the MDV is not fully open

OR i) Hot PA duct. pr. Lo & Lo - Lo occures simultaneously LoLo = <625mmWC

OR j) MFT

OR

KORBA SIMULATOR

211

k) PA / FD Fan trip a) If both PA Fans & both FD fans running & any PA or any FD Fan trips then

mills start tripping from top elevations with 2 secs time delay till 4 mills are available.

b) If both PA / FD fans trip then all mills will trip. PULV. SEAL AIR VALVES : Valve opens when : a) Pulv. start command is given OR b) Pulv. is ON Valve closes when a) Pulv. is OFF HOT AIR GATE : Hot air gate (HAG) opens when : a) Pulv is ‘ON’ AND b) Hot air gate open P.B depressed or auto HAG open command is there AND c) No HAG close command. Hot air gate closes when : I) Loss of power > 2 secs OR ii) Pulv. off OR iii) Pulv. outlet temp > 93 0 C

KORBA SIMULATOR

212

OR iv) Close P.B. depressed v) Feeder ON Time delay of 5 secs & Feeder Trips. OR vi) Auto pulv. unsuccessful start OR vii) Auto pulv. run feeder speed to minimum. FEEDER START / STOP INTERLOCKS I. Pulv. Ready is available II. Feeder speed demand at minimum III. Pulv. manual mode IV. Pulv. ignition permit available V. No feeder stop command is there VI. No MFT VII. Pulv ‘ON’ Feeder stops when : a) Ignition energy removed within 180 secs of feeder start

OR b) Feeder in manual mode & stop PB depressed

OR c) Auto Pulv. Feeder stop command d) Pulv. OFF OR

KORBA SIMULATOR

213

e) MFT OR f) No coal on belt OR g) discharge plugged PULV TEMP CONTROL A) Release air & temp control to auto if a) Pulv is ‘ON’ AND b) No HAG close command and c) HAG is open B) Open CAD to 100 % a) 5 min. after MFT OR b) Pulv ‘ON’ and HAG Close command or HAG closed on inter locks. C) Run CAD to < 5 % open (close) a) Pulv is OFF AND b) No command open CAD to 100 % D) CLOSE HAD a) Pulv. off OR b) HAG CLOSE command and HAG not closed E) RUN FEEDER SPEED TO MIN. : a) Auto pulv. run feeder speed to min. OR b) Pulv. motor current HI. > 62 amps. c) Pulv. bowl DP High OR d) Feeder OFF

KORBA SIMULATOR

214

F) Release Feeder Speed to auto. a) Feedeer proven AND b) No run feeder speed to minimum command. G) Include Feeder in Totalising Circuit. a) Feeder ‘ON’ AND b) Feeder not OFF > 15 secs. INTERLOCKS FOR Heavy oil Trip Valve ( HOTV) & Heavy Oil Recirculation Valve (HORTV) 1. HORV : (A) This can be opened by pressing the Push button (PB) from Console if All the

HONV s are closed. (B) HORV closes automatically when any HONV is not closed OR by pressing close

PB. 2. HOTV : (A) TO OPEN HOTV : Permissives SET I : 1. No. Boiler Trip persisting

2. HFO Header temperature satisfactory >930C 3. HFO supply press satisfactory > 15 Kg/cm2 4. All HONV’s closed 5. No close / Trip command 6. Open PB depressed OR SET II : 1. All HONV’s closed

KORBA SIMULATOR

215

2. MFT acted 3. HORTV open 4. Open PB depressed (B) HOTV closes automatically if any of the following conditions exists : 1. Any HONV not closed AND a) HFO pressure low < 3 Kg/cm2 b) Atom. steam Pr. low < 3.5 Kg/cm2

c) HFO Header Temperature Lo-Lo for > 2 secs. < 950C 2. Any HONV not closed and MFT acted 3. Loss of critical power > 2 Secs FLAME FAILURE VOTE LOGIC : ‘AB’ ELEVATION : a) Feeder A is OFF or LOSS of elevation ‘A’ Power > 2 sec and Feeder B is OFF or

LOSS of elevation B Power > 2 Secs.

OR b) Elevation AB 2 out of 4 nozzle valves not proven or loss of power for >2 sec.

AND Elevation AB 3 out of 4 fire ball scanners sensing no flame

OR c) Elevation AB 2 out of 4 nozzle valves not proven or loss of power for >2 secs

AND

Elevation AB any nozzle valve not closed or elevation started and power loss for 2 secs.

KORBA SIMULATOR

216

BC ELEVATION a) Feeder ‘B’ off or loss of elevation power for >2 secs andFeeder ‘C’ off or loss of

elevation Powerfor >2 secs OR

b) Elevation BC 3 out of 4 fire ball scanners sencing no flame GH is same as AB elevation. FG & DE Elevation same as BC elevation SCANNER AIR FANS 1. No fan running for 2 secs. A.C. Fan starts and if A.C. fan fails to start, D.C. Fan

starts 2. A.C. Fan running and Scanner Duct / furnace DP low (< 6" WC) D.C scanner Fan takes start. DISCHARGE DAMPERS 1. A.C. Fan running and D.C. fan off A.C. Fan discharge damper opens and D.C. fan

damper closed. 2. D.C. Fan ON and A.C. FAN OFF - D.C. fan’s discharge damper opens and A.C.

fans damper closes. 3. Scanner air Emergency damper opens on both FD fans are off. TURBINE TRIPS TRIP REASON (A) ELECTRICAL TRIPS : I) Emergency Trip From UCB Push Button II) FIRE PROTECTION a) MOT LEVEL VERY LOW LOW< -150 mm in 2 out of 3 sonar probe

b) Push Buttons

1. At UCB console 2. AT MCT room 3. Near HP turbine 4. AT LPBP rack

KORBA SIMULATOR

217

III) BOILER TRIP from FSSS VI) MCB TRIP OPERATED during ATRS S/ D V) CONDENSER VACUUM LO LO > 0.3 bar VI) LUBE OIL PRESSURE LO LO < 1.1 bar VII) EXTENDED TURBINE PORTECTION (2 / 2 LOGIC) a) Generator Bushing level hi-hi > 90 mm b) Cold gas temp. behind cooler hi-hi > 55 0 C c) Warmair main exciter temp hi-hi > 80 0 C d) Seal oil temp. behind cooler hi-hi > 60 0 C e) Primary water flow stator outlet Lo-Lo < 3.3dm3/S (47.88T/Hr) f) Primary water flow at Main Bushing Phase U lo-lo <0.37 dm3 /S (1.3 T/Hr) g) Primary water flow at Main Bushing Phase V lo-lo < 0.37 M3 / S h) H.P. casing top - bottom 50 % diff. temp hi-hi >+ 450 K i) I.P. casing front top - bottom 50 % diff. temp hi-hi >+450 K j) I.P. casing Rear top - bottom 50 % diff. temp hi-hi >+450 K k) Primary water temp. behind cooler hi-hi > 60 0 C l) Primary water flow at main bushing phase W Lo-Lo < 0.37d m3 / S m) H.P. Exhaust steam temp. hi-hi > 500 0 C B. MECHANICAL TRIPS I) OVER SPEED 11 % OF 3000 RPM II) THRUST BEARING SHIFT III) CONDENSER VACUUM LO-LO IV) LOCAL TRIP DEVICE OPERATED FROM GOVERNING RACK TDBFP START PERMISSIVES

KORBA SIMULATOR

218

1. Lub Oil Pressure Normal > 2 Kg / cm2 2. Deareator Level Normal - 610 mm 3. Seal Quench Pressure Normal > 15 Kg / cm2

4. Diff. Temp. Across Top & Bottom Of Pump > 150C Barrel Normal 5. Suction Valve Open 100 % 6. Recirculation Valve Open 100 % 7. No Turbine Trip TDBFP TRIP CONDITIONS 1. Lube Oil Pressure Lo Lo < 1 Kg/cm2 2. Exhaust Steam Pressure Hi Hi > -0.7 Kg/cm2 3. Live Steam Pressure Hi Hi (Live Steam) > 10 Kg/cm2 4. Gov. Oil Pressure Lo Lo < 4.5 Kg/cm2 5. Exhaust Steam Temp. Hi Hi > 120 0 C 6. Axial Shift Hi Hi > 0.7 MM 7. Eccentricity Hi Hi > 200 m 8. Bearing Temp. Hi Hi > 105 0 C 9. Turbine Speed Hi Hi > 6330 rpm 10. Seal Quench Water pressure very low < 10 Kg/cm2 11. Suction & Discharge Diff. Temp Of Main Pump Hi Hi > 16 0 C 12. Deareator Level Lo Lo - 2134 mm 13. Suction Valve Closed 15. A) Emergency Trip From UCB B) Emergency Trip From LCP (Local control Panel)

KORBA SIMULATOR

219

MDBFP START PERMISSIVES 1. Lube Oil Pressure Normal > 2 Kg/cm2 2. Seal Quench Pressure Normal > 15 Kg/cm2 3. Deareator Level Normal - 610 mm 4. Diff Temp Top-Bottom of BFP Barrel Normal < 15 0 C 5. Suction Valve Full Open 100 % 6. Recirculation Valve Full Open 100 % 7. Hydraulic Coupling Scoop minimum 8. Trip Command Not Persisting MDBFP TRIP CONDITIONS 1. Deareator Level Lo - Lo - 2134 mm 2. Lub. Oil Pressure Lo - Lo < 0.8 Kg/cm2 3. Suction Discharge Diff. Temp. Hi-Hi > 15 0 C 4. Working Oil Pressure Lo- Lo < 2.2 Kg/cm2 5. Working Oil Temp. Hi Hi > 130 0 C 6. Seal Quench Pressure Lo- Lo < 10 Kg/ cm2 7 Suction valve closed CEP START PERMISSIVE 1. DC Control Supply On / Available 2. Breaker Selector Switch at Switch gear in Service 3. E.P.B. in Release Position 4. Recirculation Valve Open > 90 % 5. Discharge Valve Closed or Any CEP On

KORBA SIMULATOR

220

6. Suction Valve Open 100 % 7. Breaker Not Closed 8. Hot Well Level Normal 9. Cooling Water Flow Normal 10. Switch Gear Selector Switch In ‘Remote’ Position C.E.P. PROTECTION 1. Emergency Trip From Local Push Button 2. Under Voltage Trip From Switch Gear 3. Protection Relay Contact Operated In Switch Gear 4. Hot Well Level Lo Lo -1290 mm 5. Suction Valve Close 0 % 6. Pump Running & Discharge Pressure Lo (for 5 secs Time Delay) < 20 Kg /cm 2 ARCW & DMCW START PERMISSIVE 1. D.C. Control Supply On/Available 2. Switch Gear Selector Switch To Be In Service Position 3. EPB in Released Position 4. Suction Header Pressure Ok > 2 Kg / cm2 5. Start Command Not Persisting 6. Discharge Valve Closed 0 % HP BYPASS INTERLOCKS For BP Valves :

KORBA SIMULATOR

221

1. If Condenser vacuum reaches -0.8 Kg/cm2, Manual Trip Command will go for

both BP1 & BP2 valves to close. 2. If HPBP downstream steam temp. goes beyond 3800C , BP1 & BP2 will close on

temperature protection. 3. In case of Hydraulic oil pr. low, BP valves control changes to manual and it will

become inoperative (it will remain stay put) 4. If BP valves position drops to 2% open, it will receives a close command (for positive shut off) 5. Manual Trip command will initiate incase of CRH pot level High alarm. For BPE Valves : 1. HP Bypass valves opening less than 2 % will automatically close the spray valves. 2. If opening of either of the bypass valves goes to 2%, BP1 & BP2 , valves will

switch over to Auto. 3. If hydraulic oil pressure is low BPE valves control will go to Manual and remain stayput. 4. In case of fast opening of BP valves irrespective to temp. BPE valves will open by 20 % till fast open command is persisting. Fast Opening OF HP Bypass 1. If set pressure and actual pressure deviation exceeds 20 Kg/cm2. 2. Gen breaker gets open. 3. Load shedding relay operated. 4. Depressing Fast Open push button (Fast open pulse will persist for 5 Sec.) BD Valve : In case of low Hydraulic oil pressure, it will be forced to Manual. * Actual Pr. & Set Pr. deviation +20 Kg/cm2 will initiate “HPBP Pr. Limit exceeded

alarm”.

KORBA SIMULATOR

222

Reheat Protection : Boiler will trip when any one or more of the following conditions occur : 1. Turbine Tripped or Gen CB open and HP or LP Bypass valves opening < 2% then

after 5 sec of Time delay. 2. Turbine working (control valves >2 %) and Load shedding relay actuated and if

HP or LP Bypass opening is < 2 % Reheat protection will act after 10 sec. delay. 3. If Turbine not working (HP or IP control valves < 2%) and boiler working (No.

contact of loss all fuel arming relay from FSSS) and HP or LP Bypass valves < 2 % with a time delay of 5 Sec. Reheat Proctection will act.

Arming of Reheat Protection - Once HP & LP Bypass are open 2 % and steam flow increases beyond 200T/hr Reheater protection will be armed .

KORBA SIMULATOR

223

ANALOG CONTROL SYSTEM

KORBA SIMULATOR

224

KORBA SIMULATOR

225

ANALOG CONTROL SYSTEM

In power plant industries, the four basic variables namely Pressure, Temperature, Level, and Flow of the process media needed to be continuously controlled for maintaining them within desired /required limits .Solid state electronics based Analog control system is provided in the plant for controlling various process variables (e.g. main steam pressure ,temp, flow drum level, air flow etc.)at desired value. In this type of control system analoge electrical signals (4 -20mA) are generated to represent the value of process variables using primary elements /transducers. These signals are conditioned and transmitted to electronic control system for further processing. Output of this system is used to activate the final control element e.g. control valves, dampers, guide vanes etc. so as to maintain the process variables at desired set point. This system is called Analog Control System because throughout the control starting from monitoring to conditioning ,to processing and till operating the final control element there exists a definite analogy between the input and output of various subsystems (i.e. transducer, transmitter etc.).Here the signals being processed /used for control are nothing but physical quantities current ,voltage etc. which are similar to the process variables being controlled. It is totally different from digital system wherein ,instead of physical quantities, discrete numbers are used for processing. It is necessary that all the parameters should have optimum values throughout the range of unit operation. For having control on parameters of various subsystem several control loops are in service with specific objectives. Description of following important control loops is covered here under : - 1. Hotwell level control 2. Drum level control / Feed water control 3. PA header pressure control 4. R/H temperature control 5. SH temperature control 6. Draft control Acs has got two operating channels which are simultaneously active i.e.

Teleperm - M & Teleperm - C Teleperm C - is the control system which is purely hardware based electronic wherein controls all the related logics & computation are done through electronic cards/modules only. Teleperm M - This the control which uses software in addition to hardware electronic cards. Wherein part of the computation logics are performed through software. During

KORBA SIMULATOR

226

normal operation if Tel. C fails for a particular system, that control will transfer to Tel M automatically however reverse is not possible. Selection of any of these two channel can be done from UCB depending on the healthiness of control system. Hotwell Level Control Condenser hotwell level shall be controlled by regulating the make up water flow to the condenser. The make up to condenser is primarily provided through the make up line from demineralisation plant. If the condenser make up demand exceeds the flow in DM water make up line ,the additional requirement of make up water shall be supplied from condensate storage tank. Accordingly ,the low level in hotwell shall be controlled by modulating: (a) Normal make up valve in DM water make up line. (b) Emergency make up valve in emergency make up line from CST. Hotwell level control system is provided with three separate controllers termed as Hotwell high level controller, Hotwell normal level controller and Hotwell low level controller. For high level and normal or low level there are two separate level transmitters. In all the three controllers actual Hotwell level is measured through level transmitters, Output of which is inturn converted into corresponding current signal and then voltage signal through two converters .The available voltage signal is compared with Hotwell level set value in terms of voltage. Net available voltage is fed to a PI controller and output of this used for opening or closing of respective pneumatic control valves provided for Normal, Emergency or spill control thereby controlling the makeup flow as per the demand. Actual position feed back of the valve is available in the UCB. Control circuit is provided with hard hold memory card which retains the last available value and provides smooth change over to manual whenever auto control fails. Auto control fails giving a flashing lamp on the controller module when actual level goes beyond the level transmitter range. Drum Level Control / Feed Water Control This control loop is used for controlling of drum level. Depending on the feed water flow path two separate control loops are used. Namely, single element control & three element control. Single element control :- This control system gets selected when BLI(Boiler load index)is below < 20 % and feed water flow is controlled through low range line. In this control system actual level of drum, after pressure correction, is compared with the set point and available net voltage is processed through a PID controller. Output of this controller is used for generation of pneumatic pressure for actuation of low range feed water control valve. Actual valve position is displayed in UCB. If running BFP scoop/speed is kept on auto it will slowly bring the speed to a constant value which is already preset in the control system and the feed flow will be controlled through pneumatic control valves.

KORBA SIMULATOR

227

Three element control :- Three element control is selected for higher load operation. In this control the feed flow is controlled by varying BFP speed. The set demand for scoop is achieved as follows - Actual drum level and set point difference, after taking into account input of BLI, is compared with sum of feed water flow & SH spray flow signal . The net resultant output is fed to a PI controller and subsequently the output of feed master controller sets the speed demand for TDBFP and MDBFP. Primary Air Pressure Control It is needed to maintain sufficient primary air pressure under all condition as this is essential for carrying coal from pulveriser to furnace. Under this control system actual pressure developed by PA fans is converted into voltage and is compared with the set voltage (in terms of PA header pressure)then the net available output is separately processed through two PI controllers meant for individual control loop, the output of these controllers is used to set the demand position of blade pitch of each fans. Actual position of blade pitch is available in UCB. Moreover biasing is provided for adjusting the loading between two fans. Control loop includes following interlocks 1. Control system is released for auto operation only after outlet damper has opened

fully. 2. Control system switches to manual when fan is stopped. 3. Blade pitch operation is blocked on control oil pr. LO. LO. Reheater temperature control : Reheater temperature control is achieved through burner tilt and spray. In the process of reheat temperature control, it is ensured that burner tilt operates first for bringing down the temperature and after certain time spray comes in service, likewise when reheat temperature is going down then first spray is cut-off and thereafter burner tilt is operated. Reheat temperature Control system consists of two Thermocouples one each for left and right reheat temperature measurement. For generating temp. demand set point ,output of a function generator, based on BLI and output of a manual setter on the control desk, are fed to a minimum selector. Minimum of these two signals is used as final temp. set point for burner tilt. The set point for spray control can be given with a bias from the panel itself in the range from 0 to 50c. Biasing between left and right spray valve is also provided which can be set from panel. Spray block valve will close if control valve opening becomes less than 5 %. In the control system actual reheat temp is compared with set value for temp and output is

KORBA SIMULATOR

228

processed through separate PID controllers for spray control & the demand position of spray valve and burner tilt. Demand position of RH spray valves are displayed on the panel and average tilt position along with the position feedback of all the four corners tilt position is shown separately on UCB panel. SH temperature Control In this control system SH steam outlet temp. is maintained at set point which is equal to the minimum of (1) set point manually set from UCB. (2) Set point derived through a function generator based on BLI (Boiler Load Index). Thus derived temp. set point is compared with signal corresponding to actual main steam temp. measured through thermocouple at SH outlet. Separate comparison is done for SH left and right streams . Error signals thus developed are further influenced by feedforward signals from burner tilt position and BLI. These corrected error signals are now compared with respective error signals derived by desuperheater control loop and the final error signals are given as input to two separated PID controllers ,one each for left and right streams, for finally controlling the superheater spray through pneumatically operated control valves. The controler output is displayed in UCB. An interlock is provided for closing the inlet block valve below 5% opening of control valves.. Co - ordinated Control System : As electrical energy cannot be stored in a large quantity it is necessary to balance its generation with momentary consumption. The grid frequency is the factor which indicates the degree of balance between production (generation) and the consumption. In absence of storage capacity for electrical energy it is a must for a modern power plant to have adequate control system to respond to rapid load changes and at the same time control the process/the equipments so that no part of the plant runs into a dangerous operating state i.e. the pressure, temperature and other process parameters must not cross the designed/safe limits of a particular equipment , otherwise, the availability and required safety of the man and machine will be reduced / endangered. In order to achieve best efficiency and best availability with requisite safety, it is necessary that operation of both the main plant equipments ( i.e. Boiler and Turbine) is co-ordinated using suitable control system and there should be a possibility of decoupling them during disturbances by means of bypass system. Boiler and Turbine have a number of equipments which must be able to follow their demands during unit start-up / shutdown and load variations. As a result, the power plant process has a hierarchial structure and in order to match with the process best

KORBA SIMULATOR

229

the control/automation concept adopted is also hierarchial. A typical scheme is shown in following block diagram. The above hierarchial control concept is implemented through Teleperm ‘C’ & Teleperm ‘M’ series of Siemens AG, WG make control system in case of Singrauli 500MW units. As the 500MW Simulator is designed as replica of Singrauli’s 500MW unit, the control system of the same is taken as base for discussion here. However, the general philosophy is similar to hierarchial control systems of other projects. A simple scheme of control system for unit co-ordination is shown in drawing. Depending upon various conditions/limitations of the plant equipments, different control configurations/modes are selected to carry out the unit co-ordination function. Followings are the four basic operating modes available in the control system :-

• Co-ordinated Master Control (CMC) Mode

• Boiler Follow Mode (BFM)

• Turbine Follow Mode (TFM)

• Run Back Mode The basic task of achieving balance between energy generated (supply) and its instantaneous consumption (demand) calls for generating a load set point depending upon instantaneous grid demand and permissible/allowable limits/conditions of the various plant equipments at that moment. This is called Target Load Set Point. This set point is used as guidance signal for monitoring/controlling various plant equipments/process parameters to accomplish the desired task of energy balance. The process of generating this target load set point guidance signal is discussed in following section along with four modes of unit co-ordination . Working philosophy of some of the important individual control loops of the hierarchial control system is already covered under Analog Control System above. Generation Of Load Demand Signal Load Demand is the MW set point signal for boiler combustion control and turbine (EHC). This signal is generated as follows: Target Load (MW set point) for the unit is set either by UCB operator or in auto mode from load despatch centre. Digital display is provided for target load. This target load is subject to MIN & MAX Limits, set by the UCB operator. After this limiting, target load is subjected to a rate control which various the MW set point signal at the rate set by the UCB operator or as permitted by the TSE whichever is lower. In CMC both turbine and Boiler Master (BM) are on auto hence the input to the rate controller (Known as SPCM) will be the target load set point. To this rate controlled set point a frequency influence correction signal is added and Load Demand signal is formed.

KORBA SIMULATOR

230

To ensure that the unit is following the load set point closely, an inhibit increase / decrease feature is provided. If any of MW, Throttle steam pressure, FW flow, Fuel flow & PA Header pressuredeviates from set point significantly or has reached the MAX/MIN limits, the load demand is inhibited from increasing or decreasing as the case may be. Air flow & turbine load limit active are two additional signals to inhibit increase of load demand. Boiler master and generation of fuel / air set point: The function of the boiler master auto / manual station in CMC Console is to provide a set point for fuel and air flow i.e. fuel demand and air demand signals. In Co-ordinated mode, it is equal to sum of boiler load set point and master controller (PID) output. In this mode Boiler master controller acts on DP error. The fuel demand as generated is compared with actual air flow and a minimum of the two is selected as the fuel set point. The air demand as generated is compared with fuel flow & 30 % of air flow and maximum is selected as air set point. This MIN/MAX selection ensures an air rich furnace. When fuel/air demand increases the MAX gate first increases the air set point and when fuel demand decreases the MAX gate permits reduction of air flow only after fuel has decreased. Fuel Flow control : Oil flow to burners and feeders speed (which is the measure of coal flow) along with Calorific Value(C.V) corrections added to get total fuel flow. Cabinet adjustments are provided to take care of individual calorific values to obtain total fuel flow as fuel oil equivalent (FOE). The total fuel flow (FOE) is compared with fuel set point to generated fuel control error. This control error is fed through (Pl) controller (Master Fuel Controller) to all feeders in auto and Each feeder is provided with a bias and an auto /manual station. Secondary Air Flow Control As mentioned earlier, air demand is generated as the MAX of the following:- 1) Air demand from Boiler Master 2) Air flow as calculated based on actual fuel flow 3) A safe minimum 30 % air setting At SSTPS secondary air flow is measured by aerofoil near the windbox (left & right) by two transmitters, sum of the two transmitters give the secondary air flow. Primary air flow is added to this to give total air flow which is used for combustion control, purge logic & SADC (Secondary Air Damper Control). This actual air flow is compared with the air set point and then modified by O2 trim to generate the air flow control error. This signal is doubled in case only one, out of two running fans available for automatic control. An equalising and biasing signal is added to equalise and bias the individual fan air flows. Control signal thus formed operates on the individual controller (for

KORBA SIMULATOR

231

each fan) whose output fires the thyristor drives of the 415 V AC motors for blade pitch control. An auto / manual station is provided for each fan. O2 TRIM A selection station and a setter for oxygen set point are provided to achieve the desired excess air. If variable O2 set point (SP) is selected, set point is generated by a function generator which is a function of MAX (air flow SP and total air flow). In other mode SP is set from UCB. O2 in flue gas is compared with this SP and error is fed to PI controller, output of which is limited between 0.8 and 1.2 times of total air flow. O2 PI controller output is now multiplied by total air flow and the resultant O / P signal is given to makes the FD fans blade pitch controllers for achieving desired air flow. O2 probes are provided at the outlet of economiser for measurement and control of the flue gas O2. These probes are zirconium oxide probes working on the principle of partial pressure of oxygen.Thus the input signal to FD Fan blade pitch controllers is trimmed by O2 signal to get desired Excess air / O2 set point Generation of DP / DMW Signals The pressure set point compared with actual throttle steam pressure to obtain the control error signal DP. Three pressure transmitters are provided for redundancy along with deviation monitoring and middle of the three is selected as actual pressure. In case of two transmitters fault, the control is put to manual. The pressure set point generated in this circuit is also sent to HP Bypass Control. Actual MW signal (middle value of O/P of 3 transducer) is sent from turbine control panel to CMC console where DMW signal is formed as the difference between load demand and actual MW. Selection of CMC 1. Put Air Master on Auto i.e. atleast one FD fan blade pitch controller on auto. 2. Put feeders speed control on auto after varying Fuel Master (FM) output and

making feeder speed controller error zero. 3. Vary Boiler Master Output so that FM error becomes zero. Then put FM on auto. 4. Make throttle pre. set point and actual pr. difference zero . 5. Put BM on auto 6. Increase / decrease unit master output so that it becomes equal to actual load.

(wait until load set value and load actual value matches as shown in the CMC console digital indicator)

7. From Turbine desk put turbine control on auto. 8. Press co-ordinated push button along with manual release on CMC desk.

KORBA SIMULATOR

232

Boiler Follow Mode In this mode turbine is in manual and the load is set at the turbine desk. The boiler in auto follows the turbine and fires to maintain the throttle pressure. It means boiler master has to be on Auto. If for any reason or other,the load demand set point signal is not available the turbine load has to be set manually and the system can be switched to boiler follow mode. In Boiler follow mode, set point = sum of boiler load index and Master controller output (PID) acting on DP. In Boiler Follow Mode as turbine is on manual so input to SPCM will be turbine load set point. . Selection of Boiler Follow Mode : 1) Put Air, FW & Fuel Master Controller on Auto. 2) Put Boiler Master Controller on Auto.

Note : While putting any controller on auto ensure corresponding error signal is zero.

If the unit is in co-ordinated mode automatic change over to Boiler Follow Mode occurs under following conditions a) Turbine goes to manual because of any reason.

OR b) (PrCMC - Pr lim) > 60 MW [i.e. when difference between set point guidance signal

and load set point for EHC is more than 60 MW ] Turbine Follow Mode It means turbine control has to be on Auto. On turbine follow mode the unit load is controlled through boiler, acting on the firing rate in the same manner as the steam pressure control described in CMC mode. The pressure is controlled by Pr.controller of EHC utilising the pressure deviation formed in the boiler master control system. In turbine follow mode turbine operates in initial pressure mode. In TFM set point = Sum of boiler load set point and master controller output (acting on DMW Error) Selection of Turbine follow mode: 1) Boiler master on manual 2) Confirm that throttle pressure deviation is zero 3) Put turbine in Auto from turbine desk

KORBA SIMULATOR

233

4) Press “ Turbine follow” push button along with manual release on CMC desk and turbine goes to initial pressure mode from limit pressure modes by itself. 5) Now load set point can be changed by varying the boiler master manually. Runback Mode Under runback condition the firing rate for the boiler must be reduced to pre-set values, as close as possible to the tolerable limits. Therefore the swings of firing rate caused by the action of the PID controller must be avoided. As consequence of this condition the system has to be switched to pure feed forward control, where the firing rate set point is directly proportional to the load capability signal. To avoid any mismatch between steam production of the boiler and the turbine load, the turbine has to be switched to initial pressure control, as with TFM. Runback Resetting 1) Let the boiler master be in auto 2) Reduce load set point from the turbine desk to a value slightly less than Unit

capability so that 1 0 “Runback in Operation” resets.

KORBA SIMULATOR

234

KORBA SIMULATOR

235

AUTOMATIC TURBINE RUN-UP SYSTEM

KORBA SIMULATOR

236

KORBA SIMULATOR

237

OPERATION INSTRUCTION OF SGC TURBINE The operator should have clear knowledge of the logic sequences and various criteria requirements. This is an essential prerequisite for smooth trouble free and safe operation. The operating staff should have thorough experience of operation of the turbine and its sub-systems. The sub groups (SGC) can be started in any sequence but it is suggested to switch on the four SGCs one after other, i.e. the SGC control fluid system first, SGC oil system there after SGC vacuum system, and then SGC Turbine. Before starting a particular SGC in ‘Operation or Shutdown’ direction, it is recommended to check from ATRS control console, that all the relevant enabling criteria, necessary for release of programme is available, have been actually accomplished / achieved. For this, press the push button of start up or shutdown of the particular SGC, without pressing the manual release push button. If all the criteria have been fulfilled, the fault lamp (the middle push button) should not glow by pressing this button of start up or shutdown of that particular SGC. If few criteria or a criterion is not fulfilled, then the fault lamp along with the lamps for unfulfilled criteria will glow as long as the start up or shut down button is kept pressed. After checking that all the release criteria are fulfilled, simultaneously press the manual push button of start up or shutdown in the SGC title and push button for manual release. The lamp start up or shut down shall start flickering. the programme would come to first step. The lamp for first step shall continue to glow so long as the programme stays in that step. Along with this, the lamps for unfulfilled criteria shall also glow until the same gets fulfilled as desired by the process. If the criteria do not get fulfilled within the specified monitoring time of that particular step, an alarm “SGC Monitoring Time Exceeded” will appear. In case the criteria of a particular step get fulfilled after the elapse of the monitoring time, the programme shall go ahead automatically but it will leave behind the lamp of the ‘step’ & ‘criteria’ glowing as a trace of Tell-tale story. Once the monitoring time exceeds for any step, then following shall be observed: i) Fault lamp starts flashing. ii) Start lamp or shutdown lamp starts flashing. iii) The lamps for step and unfulfilled criteria get locked up. That means if criteria

are achieved after the monitoring time has exceeded, the lamps do not go off by themselves. Note down the step and criteria number for which the lamp continued to glow and investigate the cause for the delay in getting criteria. By once pressing the push button ON/OFF (without pressing the manual

release push button) these lamps can be put off, after the criteria have been achieved.

iv) An alarm is given in case the running time of any step is exceeded.

KORBA SIMULATOR

238

When the SGC in one Step by Step mode, all the drives controlled by ATRS get switched ‘ON’ and OFF automatically by the SGC logic sequence. These drive can be operated manually also pressing the manual release push button and at the same time ON and OFF push button control interface title of the drive. The condition of the driven equipment shall be displayed by the three lamps as has been explained earlier. OPERATOR GUIDE MODE : In this mode of operation, the function group control does not have any automatic command to the control interfaces, nevertheless the logic programme is followed since sub group control receives data from the plant and control sections, but the command output is blocked. The commands to the control interface are to be given manually at the control interface tiles. For operating the unit under this mode, a lockable stay - push type switch ‘Operated Guide Mode’ has been provided on the control console. It should be turned On with the help of its key. Then start up or shutdown push button on SGC tile alongwith the manual release push button are to be pressed to bring the operation to first step of start-up/shutdown programme. Then the commands of the first step are given manually at control interface level. The programme will seek the checkback criteria and when they are fulfilled, shall just go to second step. Then again the commands for that steps are to be given at control interface level, and so on. Thus although the commands at each step are given manually, the operators strictly follow the programme and can closely watch the sequences, which otherwise in automatic mode runs through. Due to obvious reasons, in this operation mode, the alarm for “Monitoring Time exceeded” is blocked. STEP BYPASS This mode of operation suggested only in very special cases for simulating the missing criteria for any particular step. When some criteria are missing due to some fault in transmitter etc., while the plant is in healthy state and actually the criteria have been fulfilled, a deliberate decision can be taken to electrically simulate the missing criteria. For this purpose a lockable spring return switch ‘step by step mode’ has been provided on the control console.

When the programme is stuck up at any step, the switch ‘step by step mode’ is to be turned with the help of its key. Simultaneously once press the push button start up or shutdown of SGC tile, without pressing the manual release push button. This will electrically simulate the criteria for that particular step where the programme got stuck up and thereby programme shall proceed forward. Before simulating the criteria, the healthiness of plant and actual fulfilment of all the criteria must be ascertained. Automatic Runup of Turbine with ATRS should only be tried after the unit has been successfully run with manual methods and all auxiliaries, auto controls etc., have undergone successful reliable operation.

KORBA SIMULATOR

239

Even when the unit is under automatic runup, the operators should not totally withdraw their supervision on the equipments and the process parameters like vibrations, turbo-visory parameter oil flow through bearings and any other abnormality. ATRS START UP PROGRAMME (SGC TURBINE) OPERATION RELEASE: 1. Starting device 0%

2. Position set point turbine controller < 0%

3. Field breaker OFF.

4. Generator breaker OFF.

5. Drain HP control valve1 not closed.

6. Drain HP control valve2 not closed.

7. Drain HP control valve3 not closed.

8. Drain HP control valve4 not closed.

9. Limit pressure operation ON.

10. Load controller is ON.

11. Synchroniser is OFF. STEP 1 Commands : 1. SLC drains ON. 2. AVR switched to AUTO. Monitoring time - 2 Secs CRITERIA FOR STEP 2 1. SLC drains ON. 2. HP ESV1 closed. 3. HP ESV2 closed. 4. HP ESV3 closed. 5. HP ESV4 closed. 6. INTCPT ESV1 closed.

KORBA SIMULATOR

240

7. INTCPT ESV2 closed. 8. INTCPT ESV3 closed. 9. INTCPT ESV4 closed.

or

Starting device > 42 % & ESVS open.(Bypass criteria for 2 to 9)

10. HP control valve1 closed. 11. HP control valve2 closed. 12. HP control valve3 closed. 13. HP control valve4 closed. 14. INTCPT valve1 closed. 15. INTCPT valve2 closed. 16. INTCPT valve3 closed. 17. INTCPT valve4 closed. 18. CRH NRV left closed. 19. CRH NRV right closed. or

Starting device is >56% and position set point of turbine controller >0%

(Bypass criteria for 10 to19) 20. Extraction NRV A5 < 5% 21. Extraction NRV A4.1 < 5% 22. Extraction NRV A4.2 < 5% 23. Extraction NRV A3 < 5% 24. Extraction NRV A2 < 5% or Generator load >10% (Bypass criteria for 20 to 24) 25. AVR is on auto.

KORBA SIMULATOR

241

STEP 2 Commands: No command is issued. Monitoring time - 500 Secs CRITERIA FOR STEP 3 1. Turbine speed > 15 rpm. 2. Condenser pressure < 0.5Kg/cm2. 3. Any one CEP is ON. 4. Drains no fault. 5. DT HPT casing mid top/bottom < 30 0K 6. DT IPT casing front top/bottom < 30 0K 7. DT IPT casing rear top/bottom < 30 0K 8. Trip fluid pressure is > 5 Kg/ cm2 9. Drain main steam stainer1 not closed. 10. Drain main steam stainer2 not closed. 11. Drain main steam stainer3 not closed. 12. Drain main steam stainer4 not closed. 13. Drain HRH stainer1 not closed. 14. Drain HRH stainer2 not closed. 15. Drain HRH stainer3 not closed. 16. Drain HRH stainer4 not closed.

Or

Turbine speed is >300 rpm(Bypass criteria for 9-16)

KORBA SIMULATOR

242

17. Drain DW2 LPBP not closed. 18. Drain DW4 LPBP not closed. STEP 3 Commands: 1. Drain before HPCV1 close. 2. Drain before HPCV2 close. 3. Drain before HPCV3 close. 4. Drain before HPCV4 close. Monitoring time - 60 Secs. CRITERIA FOR STEP 4 1. Drain before HPCV1 closed. 2. Drain before HPCV2 closed. 3. Drain before HPCV3 closed. 4. Drain before HPCV4 closed.

or

ESVs open.

STEP 4 Commands: No command is issued. Monitoring time is blocked. CRITERIA FOR STEP 5 1. Boiler fire is ON.

2. Steam before HP BP1 > 30 0K superheat.

3. Steam before HP BP2 > 30 0K superheat.

KORBA SIMULATOR

243

4. Steam before LP BP1 > 30 0K superheat.

5. Steam before LP BP2 > 30 0K superheat

or

(Bypass criteria for 2 to 5)

HPCV1 mean temp TM is < 100 0C

HPCV2 mean temp TM is < 100 0C 6. DT (HP bypass1 - HPCV1 /TM) > X1.1 7. DT (HP bypass2 - HPCV2 /TM) > X1.2 8. DT (Wet steam1 - HPCV1) < X 2.1 9. DT (Wet steam2 - HPCV2) < X 2.2 10. Temp LSTM is < Max.

or

LSTM TEMP BEF HPESV > 400 0C

or

DT (HP BP1 - HPCV1 /TM) < X3

11. Temperature H.P control fluid > 50 0C.

12. Oil temperature after cooler > 35 0C. STEP 5 Commands : 1. Starting device raise. Monitoring time 30 secs. CRITERIA FOR STEP 6: 1. Any one ESV is not closed.

Or

KORBA SIMULATOR

244

Starting Device Position >42%. STEP 6 Commands: No command is issused. Monitoring time - 60 Secs CRITERIA FOR STEP 7: 1. HP ESV1 is open. 2. HP ESV2 is open. 3. HP ESV3 is open. 4. HP ESV4 is open. STEP 7 Commands: No Command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 8 1. Main steam flow > 15%

or

MS Strainer 1&3 and 2/4 are open.

or

Turbine speed > 2850 rpm.

2. Steam before HP BP1 > 30 0K.superheat

3. Steam before HP BP2 >30 0K.superheat

4. Steam before LP BP1 >30 0K superheat.

5. Steam before LP BP2 >30 0K superheat.

KORBA SIMULATOR

245

Commands : 1. HPCV Drain Controller switched to Auto Mode. Monitoring time - 2 Secs CRITERIA FOR STEP 9: 1. HPCV Drain Controller on Auto. or Gen Brkr is ON. or Turbine speed > 540 rpm. STEP 9 Commands : 1. Tracking device is switched ON. Monitoring time - 20 Secs CRITERIA FOR STEP 10 1. Tracking device is ON. 2. INTCPT ESV1is open. 3. INTCPT ESV2 is open. 4. INTCPT ESV3 is open. 5. INTCPT ESV4 is open. STEP 10 Commands : No command is issued. Monitoring time - 30 Secs CRITERIA FOR STEP 11

KORBA SIMULATOR

246

1. Drains no fault. 2. Speeder gear position is 100 %. 3. Seal steam pressure controller on. 4. Lub oil temperature control valve on AUTO. 5. Any One oil vapour extractor fan is ON. 6. Any one Generator bearing Exh. Fan is ON. 7. Generator bearing extractor fan 1 available. 8. Generator bearing extractor fan 2 available. 9. Hydrogen temperature controller is on AUTO. 10. Hydrogen concentration is > 94%. 11. Hydrogen Pressure (manifold) > 3 Kg/cm2 12. DP seal oil Air-Hydrogen side (T.E.) > 0.7 Kg/cm2 13. DP seal oil Air-Hydrogen side (E.E) > 0.7 Kg/cm2 14. Pressure seal oil behind pump Hydrogen side > 3 Kg/cm2 15. Seal oil pre-chamber turbine side level < MAX. 16. Seal oil pre-chamber excitor side level < MAX. 17. Liquid Level in Generator < MAX. 18. Liquid Level in Generator < MAX. 19. Liquid Level in Generator lead < MAX. 20. Liquid Level in Generator lead < MAX. 21. Any one seal oil pump Air side is ON. 22. Seal oil pump hydrogen side is ON 23. Seal oil pump 3 Air side voltage is available. 24. Primary water temperature controller is on AUTO. 25 Generator cooling water conductivity < 1.5mS/cm. 26. Any one Primary water pump is ON.

KORBA SIMULATOR

247

27. Pressure after Primary water pump is > MIN. STEP 11 Commands: No command is issued.. Monitoring time is Blocked. CRITERIA FOR STEP 12 1. Generator conditions are fulfilled (Step 10). 2. Steam before HP ESV1 SUPERHEAT > X4.1 3. Steam before HP ESV2 SUPERHEAT > X4.2 4. DT (HP ESV1 - HP CASING) > X5.1 5. DT (HP ESV2 - HP SHAFT) > X5.2 6. Turbine speed is > 15 rpm.

7. DT (LP bypass1 - IP CASING ) > 30 0K.

8. DT (LP bypass2 - IP CASING ) > 30 0K. or

9. Steam temperature before LP BP1 > 480 0 C

10. Steam temperature before LP BP2 > 480 0 C 11. Drain before HPCV1is not closed. 12. Drain before H.PCV2 is not closed. 13. Drain before HPCV3 is not closed. 14. Drain before HPCV4 is not closed. or Turbine speed is > 2850 rpm 15. Load reference is > 10 %.

KORBA SIMULATOR

248

16. Condenser pressure < 0.2 Kg/cm2 STEP 12 Commands : 1. Turbine speed reference raise. Monitoring time - 40 Secs. CRITERIA FOR STEP 13 1. Turbine speed > 360 rpm. or Gen Bkr is ON. STEP 13 No Command is issued. Monitoring time is Blocked. CRITERIA FOR STEP 14 1. Turbine speed is > 300 rpm. STEP 14 Commands: 1. Wall stress test programme - Block. Monitoring time - 180 Secs Waiting time - 180 Secs. CRITERIA FOR STEP 15 1. Wall stress test programme - Block.

Waiting time 180 secs lapsed. or

KORBA SIMULATOR

249

Wall temp HP Turbine Casing >250 0C

2. TSE Margins are > 30 0K or Turbine Speed 2850 rpm. 3. DT (HP BP1 - HP SHAFT) < X 6 STEP 15 Commands : 1. HPCV Drain Controller switched to manual mode. Monitoring time - 1 Sec. CRITERIA FOR STEP 16 1. HPCV Drain Controller on manual. 2. Gate valve Gearing is Closed. STEP 16 Commands : 1. Turbine speed set point raise. 2. Drain before HPCV1 close. 3. Drain before HPCV2 close. 4. Drain before HPCV3 close. 5. Drain before HPCV4 close. Monitoring time – 200 Secs. STEP 17 Commands : No Command issued. Monitoring time is Blocked. CRITERIA FOR STEP 18

KORBA SIMULATOR

250

1. Turbine speed is > 2950 rpm. or Gen Brkr is ON. 2. Bearing vibration Casing & Generator < Max. 3. Shaft vibration < Max.. 4. Bearing Temperature < Max. STEP 18 Commands : 1. AVR is switched to Auto. 2. Field Brkr is switched ON.

Monitoring time 40 Secs. CRITERIA FOR STEP 19 1. Field Bkr / AVR ON/AUTO or Gen Bkr ON. STEP 19 Commands : 1. Drain before HPCVs (1-4) close . Monitoring time is Blocked. CRITERIA FOR STEP 20 1. Both AOPs are OFF (timer 0- 10 secs). 2. DT (LP BP1-IP shaft) < X7. 3. H2 Casing Pressure > 3 Kg/cm2

KORBA SIMULATOR

251

4. Temp cold gas after H2 Cooler A/B < 45 0C. 5. Temp cold gas after H2 Cooler C/D < 45 0C.

6. Excitation cold air temperature < 45 0C. 7. Drain before HPCV1 is closed. 8. Drain before HPCV2 is closed. 9. Drain before HPCV3 is closed. 10. Drain before HPCV4 is closed. 11. One Seal Oil Pump Air side is ON. 12. Seal oil Pump1 Air side is available. 13. Seal oil Pump2 Air side is available.

14. Primary Water Temperature is < 50 0C. 15. Conductivity main filter is < 1.5 mS/cm. 16. Primary Water flow in Gen. & Bushing not low.

17. DT( Primary Water- H2) > 1 0K STEP 20 Commands : 1. AVR is switched to Auto. Monitoring time - 15 Secs. Waiting time - 15 Secs. CRITERIA FOR STEP 21 1. Waiting time is lapsed.. 2. AVR on Auto. 3. Generator voltage > 95%).

KORBA SIMULATOR

252

Or Generator breaker is on and Gen load >10% (Bypass criteria for 1,2,&3) STEP 21 Commands : 1. Synchroniser ON. Monitoring time - 60 Secs. CRITERIA FOR STEP 22 1. Generator Breaker is ON. STEP 22 Commands : 1. Load Reference raise. Monitoring time - 1 Sec. Waiting time - 1 Sec. CRITERIA FOR STEP 23 1. Waiting time 2 seconds. or 2. Generator load > 10 % STEP 23 Commands: No command is issued. Monitoring time -2Secs. END OF PROGRAMME

KORBA SIMULATOR

253

S.G.C TURBINE SHUT DOWN PROGRAMME STEP 51 Commands : 1. SLC drains is switched ON. Monitoring time - 2 Secs. CRITERIA FOR STEP 52 1. SLC drains is ON. STEP 52 Commands : 1. Load reference lower.

Monitoring time - 60 Secs. CRITERIA FOR STEP 53 1. Generator load is 0%. 2. Speed controller in Action. STEP 53 Commands : 1. Turbine speed set point lower. Monitoring time - 60 Secs. CRITERIA FOR STEP 54 1. Gen Brkr is OFF.

KORBA SIMULATOR

254

STEP 54 Monitoring time - 2 Secs. Commands : 1. Electrical Turbine Trip Channel 1. 2. Electrical Turbine Trip Channel 2. 3. Synchroniser OFF. 4. Field Breaker OFF. 5. Tracking Device OFF. CRITERIA FOR STEP 55 1. Synchroniser is OFF. 2. HP ESV1 closed. 3. HP ESV2 closed. 4. HP ESV3 closed. 5. HP ESV4 closed. 6. INCPTESV1 closed. 7. INCPTESV2 closed. 8. INCPTESV3 closed. 9. INCPTESV4 closed. 10. Trip fluid pr < 5 Kg/cm2 or Starting device 0% 11. Tracking device is off. 12. Overspeed Trip 1 off. 13. Overspeed Trip 2 off.

KORBA SIMULATOR

255

14. Shaft position Trip off. STEP 55 Commands: 1. Starting device lower. 2. Drains HPCV(1- 4) open. Monitoring time 120 secs. CRITERIA FOR STEP 56: 1. Drains HPCV(1- 4) closed. 2. Startind device 0%. 3. Drains no fault. STEP 56: No command issued. Monitoring time blocked. END OF SHUT DOWN

KORBA SIMULATOR

256

SUB GROUP CONTROL OIL OPERATION START-UP PROGRAMME OPERATION RELEASE: 1. Any one Oil vapour extractor is ON. STEP 1: Commands: No command is issued. Monitoring time blocked. STEP 2: Commands: 1. Auxiliary oil pumps 1 ON.

Monitoring time - 5 Secs. CRITERIA FOR STEP 3 1. Auxiliary oil pump is ON

or

Auxiliary oil pump 2 is ON.

or

Turbine speed is >2850 rpm.

2. Pressure oil pressure is > 4.8 Kg/cm2

STEP 3 Commands: 1. Lub Oil temperature controller on Auto. Monitoring time - 20 Secs. CRITERIA FOR STEP 4 1. Lub Oil temperature controller on Auto. 2. DP seal oil (Air - H2) Turbine end > 0.7 Kg/ cm2

KORBA SIMULATOR

257

3. DP seal oil (Air - H2) Exciter end > 3 Kg/cm2

4. Pressure seal oil behind pump H2 side > 3 Kg/ cm2

5. H2 concentration is > 94% 6. H2 pressure in the generator casing > 3 Kg/ cm2

7. Liquid level in generator < Max. 8. Liquid level in generator < Max. 9. Liquid level in generator lead < Max. 10. Liquid level in generator lead < Max. 11. Any one Generator bearing chamber Exhauster Fan is ON. STEP 4 Commands : 1. SLC Turning gear ON (Monitoring time 60 seconds). CRITERIA FOR STEP 5: 1. Gate valve gearing is OPEN.

or

Turbine speed >240 rpm.

2. SLC Turning gear is ON. STEP 5 Commands : 1. SLC AOP1 ON. 2. SLC AOP2 ON. 3. SLC EOP ON. 4. SLC JOPs ON. 5. SLC JOP3 ON.

KORBA SIMULATOR

258

Monitoring time - 200 Secs CRITERIA FOR STEP 6: 1. SLC AOP1 is ON. 2. SLC AOP2 is ON. 3. SLC EOP is ON. 4. SLC JOPs is ON. 5. SLC JOP3 is ON. 6. Turbine speed > 15 rpm. STEP 6 Commands: No command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 7: 1. Turbine speed is > 540 rpm. STEP 7 Commands : JOPs are switched off. Monitoring time 60 secs. CRITERIA FOR STEP 8: 1. JOP1 OFF. 2. JOP2 OFF. 3. JOP3 OFF. 4. Gate valve gearing is closed.

KORBA SIMULATOR

259

STEP 8 Commands: No command is issued. Monitoring time is Blocked. CRITERIA FOR STEP 9: 1. Turbine speed is > 2850 rpm. 2. Pilot oil pressure > 7 Kg/ cm2

STEP 9 Commands : 1. Auxiliary oil pump1 off. 2. Auxiliary oil pump2 off. Monitoring time - 5 Secs. Waiting time - 0.5 secs. CRITERIA FOR STEP 10: 1. Waiting time over.. STEP 10 Commands : No command is issued. Monitoring time - 10 Secs. Waiting time 10 secs. CRITERIA FOR STEP 11: 1. Waiting time is over.

or

Generator Load is >10%.

2. Auxiliary oil pump1 is off.

KORBA SIMULATOR

260

3. Auxiliary oil pump2 is off. 4. EOP is off. STEP 11: Commands : No command is issued. Monitoring time is Blocked SGC OIL SHUTDOWN PROGRAMME. RELEASE CRITERIA 1. Temperature HP casing TOP 50% < 100 0C. 2. Temperature HP casing BOTTOM 50% < 100 0C. STEP 51 Commands : 1. SLC Turning gear OFF. 2. Gate valve gearing closed. Monitoring time - 60 Secs CRITERIA FOR STEP 52: 1. SLC Turning gear is OFF. 2. Gate valve gearing is closed. STEP 52 Commands : No Command is issued. Monitoring time is blocked. CRITERIA FOR STEP 53: 1. Turbine speed is < 10 rpm. STEP 53 Commands :

KORBA SIMULATOR

261

No command is issued. Waiting time - 1000 Secs. CRITERIA FOR STEP 54: 1. Waiting time 1000 Secs is lapsed .

or

a. SLC AOP1 is off. b. SLC AOP2 is off. c. SLC EOP is off. d. AOP1 is off. e. AOP2 is off f. Lub oil temp. control valve is closed. STEP 54 Commands : 1. SLC JOPs off. 2. JOP1 off. 3. JOP2 off. 4. SLC JOP3 OFF. 5. Oil temperature control valve on manual.

Monitoring time - 30 Secs. CRITERIA FOR STEP 55: 1. SLC JOPs off. 2. JOP1 off. 3. JOP2 off. 4. SLC JOP3 off.

KORBA SIMULATOR

262

5. Oil temperature control valve on manual. 6. JOP3 OFF. STEP 55 Commands : 1. SLC AOP1 off. 2. SLC AOP2 off. 3. SLC EOP off. 4. AOP1 off. 5. AOP2 off. 6. Oil temperature control valve closed. Monitoring time - 30 Secs CRITERIA FOR STEP 56: 1. SLC AOP1 off. 2. SLC AOP2 off. 3. SLC EOP off. 4. AOP1 is off. 5. AOP2 is off. 6. Oil temperature control valve is closed. 7. EOP is off. STEP 56

Commands:

No command is issued.

Monitoring time - Blocked.

END OF PROGRAMME

KORBA SIMULATOR

263

SGC - EVACUATION START-UP:- RELEASE 1. Any one Seal steam exhauster fan is on. 2. Any one CEP is on. 3. Air header1 air isolating valve IV open. 4. Air header2 air isolating valve IV open. STEP 1 Commands : 1. SLC Drains switched on. Monitoring time - 2 Secs. CRITERIA FOR STEP 2: 1. SLC Drains on. Or Condenser Pressure <0.85Kg/ cm2

STEP 2 Commands : 1. Vacuum breaker closed. 2. Gland steam pressure controller on manual. 3. Gland steam control valve closed. Monitoring time - Blocked. CRITERIA FOR STEP 3 1. Vacuum breaker closed. 2. Gland steam pressure controller on manual. 3. Gland steam control valve closed.

KORBA SIMULATOR

264

STEP 3 Commands: 1. Vacuum pump1 ON. 2. Air IV1 open. 3. Vacuum pump2 ON. 4. Air IV2 open.

Monitoring time - 120 Secs CRITERIA FOR STEP 4: 1. Vacuum pump1 ON. 2. Air IV1 open. 3. Vacuum pump2 ON. 4. Air IV2 open. STEP4 Commands : No command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 5: 1. Turbine speed is > 15 rpm. 2. Condenser pressure < 0.85 Kg/ cm2

STEP 5 Commands : 1. Gland steam pressure controller on auto.

Monitoring time - 30 Secs

KORBA SIMULATOR

265

CRITERIA FOR STEP 6: 1. Gland steam pressure controller on auto. 2. Shaft seal steam pressure is not high. 3. Shaft seal steam pressure is not low. STEP 6 Commands : No command is issued. Monitoring time - Blocked. CRITERIA FOR STEP 7: 1. Condenser pressure is < 0.12 Kg/ cm2

2. Generator Load > 5 %. STEP 7 Commands : 1. Vacuum pump 1 or 2 OFF. 2. Air valve 1 or 2 closed. (If the vacuum pump 1 or 2 pre-selected respectively) Monitoring time - 60 Secs. CRITERIA FOR STEP 8: 1. Vacuum pump 1 is OFF, Air IV 1 closed. Or 2. Vacuum pump 2 is OFF, Air IV 2 closed. STEP 8 Commands: No command is issued.

KORBA SIMULATOR

266

Monitoring time - Blocked. CRITERIA FOR STEP 9: 1. Condenser pressure > 0.12 Kg/ cm2

STEP 9 Commands: 1. Vacuum pump 1 ON & Air IV1 open. 2. Vacuum pump 2 ON & Air IV2 open. Monitoring time -120 Secs. CRITERIA FOR STEP 10: 1. Vacuum pump1 ON & Air IV1 open. 2. Vacuum pump2 ON & Air IV2 open. Commands: No command is issued. Monitoring blocked.

SGC EVACUATION SHUTDOWN :-

Release Conditions: Nil. CRITERIA FOR STEP 51: 1. Turbine speed < 200 rpm. STEP 51 Commands : 1. Vacuum pump1 OFF. 2. Air IV1 close. 3. Vacuum pump2 OFF. 4. Air IV2 close.

Monitoring time - 60 Secs

KORBA SIMULATOR

267

CRITERIA FOR STEP 52: 1. Vacuum pump1 OFF. 2. Air IV1 closed. 3. Vacuum pump2 OFF. 4. Air IV2 closed. STEP 52 Commands : 1. Vacuum breaker open. Monitoring time - 30 Secs. CRITERIA FOR STEP 53: 1. Vacuum breaker open. STEP 53 Commands : 1. SLC drains ON. 2. Gland steam pressure controller on manual. 3. Gland steam control valve closed. CRITERIA FOR STEP 54: 1. SLC drains ON. 2. Gland steam pressure controller on manual. 3. Gland steam control valve closed. STEP 54: Commands : 1. No command is issued. 2. Monitoring time is blocked.

END OF SHUT DOWN PROGRAMME

KORBA SIMULATOR

268

SGC HP CONTROL FLUID - START UP RELEASE: HP Control fluid tank temp.> 20 0C. STEP1 Commands : 1. SLC CTRL FLUID PUMPS ON. CRITERIA FOR STEP2: 1. HP Control Fluid pr is > 30 Kg/cm2. STEP 2 Commands : 1. HP C/F Control valve on Auto. 2. SLC Ctrl Fluid Heater ON. 3. HP C/F Circ P/P1 ON. SGC HP CONTROL FLUID SHUT DOWN SHUT DOWN RELEASE : 1. Boiler Fire is off 2. Seal Steam pr Control is off. 3. Condenser 1& 2 Abs pressure is >.4 Kg/cm2 4. Gland Steam valve is closed. STEP 1 Commands: 1. HP Control Fluid Pump 1 & 2 off 2. HP Control Fluid Circulating Pump 1 & 2 off 3. SLC HP Control Fluid Off 4. HP Control Fluid Temp. control valve Manual 5. HP Control Fluid Temp. control valve close.

KORBA SIMULATOR

269

SGC GENERATOR EXCITER Drying: Generator exciter drying is switched on automatically if SLC is on and turbine speed is less then 210 rpm. The exciter dome and frame flapper are closed on interlock with drying ON. Similarly if turbine speed is more than 240 rpm, and the SLC is on the Gen. Exciter dryer is switched off. Heating: If SLC Exciter dryer is on & the speed of turbine is <210 rpm and exciter top casing temp is below 450C, Exciter Shut down Heating is switched on and when turbine speed > 240 rpm and top casing temp >500C Heating is switched off. Also if dryers are off, Heating is switched off on interlock. If the heating is switched on, it shall also, automatically close exciter dome flap and flaps 1 & 2 on frame. Excitor flap(Dome): It is opened automatically on protection if cold air temperature is >450C or manually through P.B. Open command. Exciter flap is closed automatically if exciter heating is On or drying is on. The release for closing is, frame flaps 1 and 2 must be closed. The manual P.B. command for closing can close the exciter flap (dome) if release is available. Exciter Flap Frame(1/2): Release:- If exciter flap(dome) is open and cold air temperature is >450C, frame flaps 1 & 2 are opened on protection or through manual push button commands flaps can be opened. Alarms: Exciter drying not ON: When turbine speed is 210 rpm and exciter top casing temperature is <450C, if exciter drying or heating is off , this alarm is initiated.

Exciter drying not off: This alarm is initiated if turbine speed is >240 rpm and drying or heating is on GENERATOR FIELD BREAKER:

KORBA SIMULATOR

270

The field breaker is released for closing only if turbine speed is >2850 rpm. It can be closed by manual “close” command or by auto SGC TURBINE command (step-18) AUTO SYNCHRONISER: It can be switched on if manual synchornise SGC “release “ command is issued and SGC Turbine step 21 Auto synchroniser ON Command is available or manual “on” command P.B. is pressed: provided turbine speed is more than 2850 rpm. The synchorniser is switched ON if any of the following conditions are not present • Manual “off “command • AVR fault • EHC speed control fault • SGC turbine step 54(Shut down from ATRS) • Generator breaker is on.

KORBA SIMULATOR

271

ELECTRICAL PROTECTION

KORBA SIMULATOR

272

KORBA SIMULATOR

273

ELECTRICAL PROTECTION 1. Differential Protection :

a. Generator Differential (87GR, 87GY, 87GB)

b. GT HV winding differential cum overhead line protection (87HVR, 87HVY, 87HVR)

c. UAT differential (87 UTA, 87 UTB)

d. GT differential protection (87 T)

e. GT Overall Differential Protection (87 GT)

2. Earth Fault Protection :

a. Stator earth fault standby E/F

b. ( 64 G1, 64G2, 64 G3)

c. GT standby E/F protection (51 MGT) 3. Stator interturn fault 4. Negative phase sequence 5. Generator back-up impedence protection 6. Loss of excitation 7. Pole slipping 8. Over voltage 9. Over fluxing 10. Low forward power 11. Reverse power 12. Generator LBB protection 13. Generator transformer protection

a) Buchholtz operation

b) Winding temperature high

c) Oil temperature high

KORBA SIMULATOR

274

d) Fire protection

14. UAT protection DIFFERENTIAL PROTECTION GENERATOR DIFFERENTIAL A direct short circuit between different phases with or without ground fault of the winding causes a severe fault current to flow inside the affected machine and cause highly extensive damage. As a result there is a distinct difference between the current at the neutral and terminal ends of the particular winding. This difference is detected by the differential relay. The current entering and leaving the protected object is determined by current transformers and compared by relays by means of a differential circuits. A fault inside the protected zone is fed from either one side or both sides depending upon the current sources present, thus producing a difference current in the differential circuit. If this differential current exceeds a set percentage of the current flowing in the protected object, the relay picks up. The relays used is designated 87GR, 87GY, 87GB type CAG34. It is set to operate current which corresponds to 1000 Amp fault current . 5% of 5 amp with stabilising resistors. Rstab = 400 ohm. UATS DIFFERENTIAL Since UATs are connected directly to the stator windings, so it has been provided with a biased differential protection in a similar circulating current scheme. The relay are designated 87 UTA and 87 UTB are DTH 31 type. GT OVERHEAD LINE DIFFERENTIAL The 400 KV bushings of the generator transformer are connected to the switchyard by double moose conductor overhead line. Any fault occurring on these lines is detected by overhead line differential protection. The relay designated 87 HVR, 87HVY, 87HVB CAG 34 type 0.1 amp with stabilising resistor of 685 ohm. It picks up at 100 Amp. fault current. G T RESTRICTED EARTH FAULT The H.V. winding of the generator transformer is star connected and the neutral is solidly earthed. The protection is meant for complete protection of H.V. winding of generator transformer. The delta side of the generator transformer is considered as a part of the generator and its earth fault would cause the earth fault current to flow towards the generator neutral and be detected as generator earth fault.

KORBA SIMULATOR

275

The relay designated as 64 GT and is CAG 14 type one amp and impedence definite current attracted armature type. G.T. OVERALL DIFFERENTIAL Since generator transformer is directly connected to it would be proper to include the transformer windings including those for UAT HV side and conductors in a current protection scheme. The relay is designated 87 GT and is of DTH 32 type 5 Amp which is a biased differential type relay.

Biased setting of 30% is used to prevent the relay operation in case of a through fault when the current transformer may saturate and produce an erroneous secondary current. EARTH FAULT PROTECTION STATOR EARTH FAULT (MAIN) The generator neutral is earthed through the primary winding of neutral grounding transformer of the rating 60 KVA, 18/.24 KV ratio. The secondary winding of the transformer is shorted through loading resistance of 0.410 ohms. For an earth fault in the generator the E/F current flows in the primary of the neutral grounding transformer. As a result a voltage across the resistor is developed which activates stator E/F sensing relay.

The reason for this kind of protection is due to the mechanical damages resulting from the insulation fatigue creepage of the conductor bases, vibration of the conductors or other fittings of the cooling systems.

The earth fault relay designated is VDG 14 type 64 G 1. The relay has a inverse definite minimum time characteristics.

Generally 5% of the generator winding starting from neutral point remains unprotected because a fault in this portion will generate too low a voltage for relay operation. STATOR STANDBY EARTH FAULT The relay is connected across an open delta of the generator PT secondary windings. When there is no E/F the sum of the phase voltages of the generator and hence the voltage across the relay is zero. The voltage across the point A & B will assume a positive value when one phase voltage of the generator drops because of earth fault on that phase.

The relay designated is 64 G2 VDG 14 type. It has an inverse time voltage characteristics.

KORBA SIMULATOR

276

ROTOR EARTH FAULT Ground leakage in the rotor circuit of a generator does not adversely affect operation, if it occurs only at one point. Danger arises if a second fault occurs causing the current to be diverted in part at least, from the intervening turns which can burn the conductor causing severe damage to rotor. If a large portion of winding is shorted the field flux pattern may change causing the flux concentration at one pole and wide dispensation at the other. The attractive forces which are proportional to the square of the flux density will be stronger at one pole than the other which will cause high vibration and may damage the bearings and may sufficiently displace rotor thereby fouling the stator. Rotor E/F is proved by monitoring the I / R value of rotor winding. < 80 k ohm Alarm < 5 K ohm Trip STATOR INTER-TURN FAULT When leakage occurs between the turns in the same phase of a winding the induced voltage is reduced and there will be a voltage difference between the centre of the terminal voltage triangle and the neutral of the machine. Therefore, in a generator having one winding per phase, a voltage transformer is connected between each phase terminal and neutral of the winding, the secondary transformer leads being connected in open delta, when inter-turn leakage occurs at the ends of the open delta, it is detected by a polarised voltage relay.

For generators having several parallel windings per phase, the neutral ends are connected together to form as many neutrals as there are parallel windings per phase. These neutrals are then joined through current transformer to current relays, or through voltage transformer to voltage relay. If an inter-turn fault occurs in the machine, the current transformer carries a transient current or alternatively voltage transformer produces a voltage thereby picking up the relay and tripping the generator.

The relay is designated 95G, is a VDG 14 type 5 amp attracted armature voltage operated IDMT (Inverse Definite Minimum Time) type .

NEGATIVE PHASE SEQUENCE A three phase balanced load produces a reaction field which is constant and rotates synchronously with the rotor field system. Any unbalanced condition could be resolved into positive, negative and zero sequence components. The positive sequence component is similar to the balanced load. The zero sequence components does not produce armature reaction. The negative sequence component is similar to that of positive sequence but the resulting reaction field rotates in the opposite direction. Hence the flux produced by the negative phase sequence current cuts the rotor at

KORBA SIMULATOR

277

double the rotational speed thereby inducing double frequency current. As a result eddy currents produced are very large and cause severe heating of the rotor windings particularly damper windings.

For any current conditions in the three phases the amount of unbalance can be determined from the values of the negative sequence components I2 of current by the method of symmetrical components.

The degree of unbalance is taken to be the value of the negative sequence current component expressed as percentage of rated current. The losses in the rotor are proportional to the square of the degree of unbalance. This generator has I22.t =8 characteristics indicating that within the generator is capable of withstanding but beyond it there is time delay of 5 sec.

The time delay has to be matched to the machine negative sequence current withstand capability.

The relay used is designated 46GA, 46GT and is of solid state design & CTNM+VTT11 type with fixed resistors.

GENERATOR BACK-UP IMPEDANCE PROTECTION A three phase zone impedance relay is provided for the back-up protection of generator against external three phase and phase to phase fault in 400 KV system. The zone of impedance relay should be extended beyond 400KV switchyard and it should be connected to trip the generator after a time delay of 2 seconds so that the generator is tripped only when 400KV protection has not cleared the fault even in the second zone. The relay used is designated 21GRY, 21GRB, 21 GBR, type CG15A FIELD FAILURE. Failure of the field system leads to losing of synchronism and resulting in running above synchronous speed. It acts as an induction generator, the main flux being produced by wattless stator current drawn from the system. Operation as an induction generator necessitates the flow of slip frequency current in the rotor, damper winding, slot wedges, excitation under these conditions requires a large reactive component which approaches the value of rated output of the machine. Since rotor would get overheated due to slip frequency current, the machine should not run more than a few seconds without excitation. Also it could overload the grid which may not be able to supply the required excitation MVAR. When loss of excitation is accompanied by under voltage it will initiate class A trip. Otherwise class B trip if the grid is able to sustain the voltage dip. The relay used is designated 40 G YCGF11 type.

KORBA SIMULATOR

278

POLE SLIPPING The asynchronous operation of the machine while the excitation is still intact unlike loss of excitation, causes severe shock both to machine and grid due to violent oscillations both active and reactive power. Because of it the machine may fall out of step or usually known as pole slipping trip.

The oscillation may disappear in a few seconds in which case it is not desirable to trip the machine. If however the angular displacement of the rotor exceeds the stability limit the rotor will slip a pole pitch. If this disturbance has been sufficiently reduced by the time this has occurred, the machine may regain synchronism, but if it does not, it must be isolated from the system.

The swing curves can be detected by an impedance relay. The relay has measuring elements set at two values near the impedance as seen by the relay. As the impedance seen by the relay changes it comes in the operating zone of the two relays one after the other. The sequential operation is observed by auxiliary relays. Since the system faults would suddenly change the system impedance both the relays shall operate within 55 cms. However, during pole slipping the two elements would operate sequentially and a trip command is given when both have operated.

The relay can be set to be in operation for swings up plus minus 90 deg. Corresponding to the stability limit of the generator. The relay used is designated 98G and is of solid state design of ZTO11 + YTGM14. In order to discriminate against swings on the grid the tripping is through impedance, relay (98 GY) set with a reach upto the 400KV yard. Current setting is 90% of 5 amp. OVER VOLTAGE The generator winding is rated for 21 KV terminal voltage sustained over voltage would unduly stress the winding insulation and may lead to failure after some time. To protect the machine against over voltage the protection relay senses the voltage at the secondary of the bus duct Pts. The relay is set to operate at 105% rise in the terminal voltage. A time delay of 3 seconds is provided to take care of transient over voltage arising from line charging, switching capacitive faults etc. The relay used is designated 59G & is VTU 21 type 110V A.C. G.T. OVER FLUXING The iron core of the generator transformer carries the flux to produce required emf. If the flux increase unduly the magnetic circuits of the generator, generator transformer become over saturated resulting in high magnetising current. This in turn leads to higher iron losses which will increase the winding temp. of the transformer. Since core can be damaged because of the overheating, protection has to be provided against it. The flux is dependent on ratio of voltage & frequency.

KORBA SIMULATOR

279

The condition of over fluxing could arise in case the voltage at the machine terminal rises or its frequency drops or both occurring simultaneously. Practically this condition will arise if the machine AVR misbehaves thereby unduly increasing the voltage even when the grid frequency is low. The relay used is designated 99GT and GTT21 + VTT11 type which senses v/f ratio at the secondary of the bus duct P.T. and gives alarm and trip signals at different time delay. The adopted setting for relay is v/f = 1.18 P.U. i.e. 20% higher than rated v/f ratio. Alarm is set at .5sec and trip at 2 sec.. This v/f relay also generates a AVR ‘ Raise’ block. Surge voltages originating from lines because of switching or atmospheric disturbances are dealt with directly by lightning arrestor and surge diverters. LOW FORWARD POWER PROTECTION When a generator, synchronised with grid, loses its driving force the generator remains in synchronism. The generator should be isolated from the grid after the steam flow ceases and the flow of power to grid reduces to minimum i.e. the point when the generator starts drawing power from the grid and acts as motor. When the load on generator drops to less than 0.5 percent, generator low forward power relay gets energised and with turbine tripped or stop valves closed, trips the generator with a time delay of 2 seconds. This is a protection to trip generator other than electrical faults. Also this protection is used for a few electrical faults where generator trip can be delayed. However, provision for time lag unit is there to prevent undesired operation from transient power reversal. The power relay used is designated 37GA, GB and is a WCD13+VTT11. acts as a final back-up to both L.P.F. protection. Local Breaker Back-up Protection This is a protection against the main generator breaker failure which may occur due to - i) Mechanical failure ii) Trip circuits not healthy Hence, this protection acts as a back-up to the main generator by tripping all the breakers connected to that particular bus.

KORBA SIMULATOR

280

RELAY SENSING: i) D.C. to the relay extended through the trip command (either 86G or 286 G or

B/B protection trip) ii) Over current element senses that generator breaker that generator breaker

contacts have failed to open. When both above conditions satisfied LBB protection acts with a timer ( 0.2 secs.) to trip all other breakers connected to that bus. The LBB protection initiates bus bar protection. (Refer to the bus bar protection scheme). The relay used is designated as 50Z, CTIG39+VTT11 type. GENERATOR TRANSFORMER PROTECTION (A) G.T. BUCHHOLZ OPERATION Any internal fault in generator transformer the winding temperature increase rapidly resulting in vaporisation of oil dissociation of oil accompanied by generation of gas. The generator gas is utilised for relay operation., The relay is a gas operated device arranged in the pipe line between the transformer tank and separate oil conservator. In the fig. The vessel is full of oil. It contains two floats B1 and B2 which are to be hinged and to be passed by their buoyancy against two stops. If gas bubbles are generated in the transformer due to fault, they will rise and get trapped in the upper part of the relay chamber thereby displacing the oil and lowering the float B1. This sinks and eventually closes an external contact which operates as an alarm. If the rate of generation of gas is small the lower float B2 is unaffected. When the fault is dangerous and gas production is violent the sudden displacement of oil along with the pipe tips the float B2 and causes a second contact to be closed and making the trip circuit and operating the main switches on both HV & LV side. Gas is not produced until temperature exceeds about 150 deg.c., so momentary overload of transformer does not affect the relay unless the transformer is really hot. Also insufficient oil level in Buchholz relay could lead to inadvertent operation of the same. B) THERMAL OVERLOAD PROTECTION Vapour pressure thermometers or resistance temperature detectors are used for this purpose. The transformer winding temperature and oil temperature are continuously monitored; when the temperature reaches a certain value it will give indication. Then the load on the transformer is to be reduced. If the temperature rises still further tripping will take place.

KORBA SIMULATOR

281

C) FIRE PROTECTION Sprinkler system is used to protect the transformer from fire hazards. Sprinkler installation comprising a system of interconnected pipes into which sprinkler heads are fitted on a definite basis of distribution, according to the network design. Sprinkler heads are so constructed that the heat arising from fire will cause them to rupture. Generally the sprinkler system consists of a compressed air line and a water line. Sprinkler heads are provided in the compressed air line. The compressed air line will always be in changed condition and prevents the contractor from entering the water line. When the sprinkler heads then the pressure in the water header will open to send the water into the water header, from water will be sprinkled on to the transformer.

KORBA SIMULATOR

282

GE

NE

RA

TO

R P

RO

TE

CT

ION

KORBA SIMULATOR

283

GE

NE

RA

TO

R P

RO

TE

CT

ION

KORBA SIMULATOR

284

GE

NE

RA

TO

R P

RO

TE

CT

ION

KORBA SIMULATOR

285

POWER PLANT CHEMISTRY

KORBA SIMULATOR

286

KORBA SIMULATOR

287

POWER PLANT CHEMISTRY

INTRODUCTION: In a modern Thermal Power Plant, the life expectancy of equipment is about 30-40 years. The plant utilizes the best material and technology in designing the critical plant items such as boiler, turbine generator etc. The control of chemical parameters is an important task to achieve the goal set for the life of a power plant. The control is being done at various stages in operation of the plant. The objectives of water Chemistry control are: 1. Prevent or minimise corrosion in boiler, feed and steam systems. 2. To prevent or minimise deposition of oxides or scales on heat transfer Surfaces. 3. To maintain high level of steam purity and thus prevent problems in the super

heater, reheater and turbine.

Besides above Power Plant Chemistry covers a vide area of service which affect the station availability and efficiency as well as Operation, Maintenance and Safety. to achieve the objectives the control are divided into following headings: 1. Water Treatment 2. Chemical control of Water/Steam cycle 3. Control of quality of lubricating/control fluids 4. Control of fuel quality 5. Monitoring losses, equipment efficiency and environment WATER TREATMENT : DESIGN

The design & operation of W.T. Plant depends upon the feed & boiler water requirement. In Korba Super Thermal Power Station the design parameter for the W.T. Plant are as follows: (for 3 x 500MW units)

Sl No Parameter pH Turbidity NTU

Organic ppm

SiO2 ppm

Conductivity ms/cm

1 Clarified Water

7.0-7.5 10-20 Nil -- --

2 D.M.Water 6.8-7.2 -- Nil <0.01 <0.01

KORBA SIMULATOR

288

REATMENT The treatment of water in KSTPS is being done in Two steps. A) PRE-TREATMENT B) DE-MINERALIZATION a) Pre-Treatment:- The river water contains suspended and organic impurities. The removal of these impurities is done by the process of coagulation/flocculation in a Clarifier. The chemicals like Alum & Lime are added to catalyse the process. Chlorine is also added to disinfect the water. b) De-mineralization:- In second step, the treatment of water is affected by a series of filters and ion-exchangers. The filter and specific ion-exchanger remove the suspended particles and dissolve solid present in water. The ion-exchanger uses specific type of resins capable of removing cation (calcium, Magnesium, Iron, Aluminium etc.) or Anion (Chloride, sulphate, silicates etc.). Beside this degasification of water is also done and undesirable CO2 is removed. The final water is taken to a mixed resin exchanger (containing cation and Anion Resins) which removes the last traces of dissolve impurities and achieve the D.M. Water quality mentioned elsewhere. The exchangers (Cation, Anion & Mixed) are regenerated separately utilizing acid and alkali to restore the exchange capacity. The general schemes for pre-treatment and demineralisation of water are follows:

PRETREATMENT AND DEMINERALISATION PLANT

KORBA SIMULATOR

289

To achieve the design water quality the proper operation of W.T. Plant and control of chemical parameters are very essential. The quality of D.M. Water directly affects the corrosion, sealing & deposition of heat exchangers and other equipments during steam generation processors. 2. CHEMICAL CONTROL OF WATER/STEAM CYCLE The demineralised water produced in W.T. Plant is utilised for steam generation. The main objective is to prevent or minimise the corrosion, deposition or scale forming on various system. To achieve this objective various treatment in Water/steam cycle is done. This includes the dosing of alkaline chemicals such as Ammonia and tri sodium phosphate. These chemicals help in maintaining alkalinity in water/steam cycle thus minimising effect of corrosive species and eliminating the scale forming salts. Second type of chemical is deoxyfier (Hydrazine) in nature. It removes the last trace of dissolve oxygen from the feed water, which may accelerate the rate of corrosion. A part from this condensate purification plant is also provided in Water/Steam chain. This plant purifies the condensate thus eliminating the deposition of oxides and other corrosion product in feed, boiler and steam circuits. To monitor the chemical parameters, On line instrumentation is provided. The lists of various instruments are as below: INSTRUMENT LOCATION Conductivity Meter Condensate Feed Boiler Steam Oxygen Analyser Condensate Feed Hydrazine Analyser Feed pH meter Condensate Boiler Steam Silica Analyser D.M. Water Boiler Phosphate Analyser Boiler Sodium Analyser Condensate Steam The various design parameters of Water/Steam cycle are as below: (for 3x500 MW units)

KORBA SIMULATOR

290

PARAMETERS CONDENSATE FEED BOILER STEAM

Ph 9.0-9.2 9.0-9.2 9.1-9.2 9.0-9.2

Ammonia, ppm 0.5-1.0 0.5-1.0 –– 0.5-1.0

Hydrazine, ppm –– 0.01-0.02 –– ––

Silica, ppm 0.010 0.010 <0.10 0.01

Sodium, ppm 0.005 –– –– 0.005

Dissolve oxygen, ppm 0.04 0.005 –– ––

Phosphate, ppm –– –– 1-2 ––

Copper, ppm 0.003 0.003 –– 0.003

Iron, ppm 0.01 0.01 –– 0.01

Chloride, ppm –– –– 0.5 ––

The schematic indicating various chemical feeding points & sample/instrument location:

LOCATION OF SAMPLING AND DOSING POINTS

GENERATOR COOLING SYSTEM 1. PRIMARY STATOR WATER SYSTEM: The generator winding is cooled by D.M. Water. The chemical control for the system is done in two ways: a) Removal of dissolve oxygen and other corrosion product.

KORBA SIMULATOR

291

b) Alkalisation In first case for degassification high purity nitrogen is used. The corrosion product or other ionic species are removed from the circuit with the help of a polishing unit. In second case stator water is made alkaline by addition of caustic soda. This help in minimising the corrosion of copper and steel. The parameters of primary stator water system are:(for 3x500MW units)

pH :

8.5-9.0

Conductivity ms/cm :

1.5-2.2

Dissolved oxygen ppm :

<0.03

Copper ppm :

<0.02

Iron, ppm :

<0.02

2. HYDROGEN:- The generator is also cooled by pure hydrogen. The purity of hydrogen and moisture contents are determined in laboratory for corrective action. The limiting parameters are as below: i) H2 Gas purity : 97% minimum ii) H2 Gas dew point : <10oC at frame pressure 3. CONTROL OF QUALITY OF LUBRICATING/CONTROL FLUIDS. The lubricants & control fluids used in power plant deteriorate on time by oxidation and by ingress of foreign matter. The quality of lubricant to be monitor in a fixed interval for: a) Viscosity b) Acidity c) Foaming characteristics d) De emulsification Nos. e) Moisture contents

KORBA SIMULATOR

292

f) Mechanical impurities The corrective action/rejection of lubricating oil/control fluid suggested if deviations in parameters are observed. 4. CONTROL OF FUEL QUALITY KSTPS get coal and oil from outside. The payment is done on the basis of grade and calorific value of fuels. The sampling done jointly with Coal Company and the grade is being determined. Similarly for oil the samples are being drawn on receipt of the oil rack for determination of Calorific value. 5. MONITORING OF LOSSES, EFFICIENCY & ENVIRONMENT A) LOSSES: In combustion process coal is burnt in boiler the losses occurred with carry-over of unburnt carbon along with ash. The quantity of unburnt is direct measure of fuel loss in system. The monitoring is regularly done and corrective action suggested controlling the losses to permissible limit. B) EFFICIENCY: During monitoring of plant/equipments efficiency various parameters needed are mentioned as below: i) % of oxygen in flue gas ii) Fineness of pulverised coal iii) Proximate analysis of coal iv) Analysis of ash These parameters are provided to various groups for efficiency calculation. C) ENVIRONMENT Thermal Power Plant uses coal and oil as fuel. On combustion various constituents are produced causes degradation of environment. Therefore, it is very essential to monitor and control these constituents at the source. The table below give various constituents monitored and their limits:

KORBA SIMULATOR

293

I) ATMOSPHERIC POLLUTION Stack Emission Ambient Air mg/Nm3 ug/Nm3 Suspended Particulated 150 500 Oxides sulphur –– 120 Oxides Nitrogen –– 120 II) WATER POLLUTION S.S.ppm 100 pH 5.5-9.0 Chloride, ppm 1000

Oil, ppm 10 BOD, ppm 30 COD, ppm 250

KORBA SIMULATOR

294

KORBA SIMULATOR

295

EMERGENCY HANDLING

KORBA SIMULATOR

296

KORBA SIMULATOR

297

EMERGENCY OPERATION

Emergency 1 : MOP COUPLING FAILURE

CAUSE : MECHANICAL FAILURE 1. Pilot oil pressure low alarm will appears 2. Standby AOP will start on AUTO. 3. HPT front bearing vibration becomes high 4. TG bearing vibration high (>35 microns) 5. ABS shaft vibration BRG1 casing front & BRG 1/2 rear increases 6. Speed controller output will go to maximum 7. MW goes up due to control valve opening 8. Turbine rpm indicator will show gradual fall 9. Speeder gear becomes ineffective NOTE : Prolonged operation under this condition is not

recommended Emergency 2 : MAIN TURBINE EHTC FAILS HI

CAUSE : SPURIOUS ELECTRICAL MALFUNCTION

1. Plunger coil output increases 2. EHTC fault annunciation appears 3. Opening of HP control vlv increases a result of higher EHTC output 4. Unit load increases unless tracking device is 'ON' 5. Else tracking device will take control and stabilise load

NOTE : Turbine should be taken on Hydraulic governor to control

unit load.

KORBA SIMULATOR

298

Emergency 3 : FIRE PROT OPERATED (for fire protection-2)

CAUSE : SPURIOUS SIGNAL

Electrical turbine trip is initiated 1. Fire protection operated alarm comes on. 2. HP control fluid pump trip 3. SLC Aux. oil pump - 2 goes off 4. SLC jack oil pump goes off 5. SLC jack oil pump - 3 goes off 6. SLC turning gear goes off 7. SGC oil supply goes off 8. SLC emergency oil pump goes on 9. Vacuum breaker opens 10. HP CTRL fluid pumps 1 & 2 off. 11. HP CTRL fluid pressure comes to Zero 12. LP CTRL fluid pressure comes to Zero 13. SLC Aux. oil pump goes off 14. SLC jack oil pump goes off 15. SLC turning gear goes off Emergency 4 : TRB TRIP DUE TO TOP/BOT DT

CAUSE : THERMO COUPLE FAULT (PARTIALLY BURNT) (BOTTOM SENSER)

1. Differential temperature of turbine casing high 2. Top/Bot diff temp reaches turbine trip limit (+45oK)

KORBA SIMULATOR

299

3. Annunciation HP/IP casing diff temp High /Trip appear. 4. DT HP out cas Top/Bot high alarm appears. 5. Turbine Trips 6. Turbine trip annunciation appears. Emergency 5 : ALL DMCW PMPS TRIP

CAUSE : PRESSURE SWITCH LATCHES ON AND GETS STUCK, DUE

TO LOW SUCTION PRESSURE ON STARTING 3rd DMCW PUMP WITH DISCHARGE VALVE FULLY OPEN OR HEAVILY PASSING

1. Start permissive for all CEP's will go "Motor cooling water flow LO" 2. All CEP bearing temperature starts rising 3. DM water pump discharge pressure decreases 4. If DMCW pump A trips: DMCW pump - A motor current decreases to zero DMCW pump A motor status become trip DMCW pump A motor trip 5. If DMCW pumps B trips: DMCW pump - B motor current decreases to zero DMCW pump B motor status becomes trip DMCW pumps B motor trip 6. If DMCW pump C trips: DMCW pump - C motor current goes to zero DMCW pump C motor status become trip DMCW pumps C motor trip 7. DM water pump discharge pressure decreases 8. All bearing temperatures will rise, Hydrogen gas, PW , exciter hot air temperatures increases. Unit may trip on any of the above temperature high protection. Emergency 6 : 220 V DC FAILURE

CAUSE : GRP DC SUPPLY FUSE BLOWN 1. All HT breaker indication lamp will stop glowing. 2. DC voltmeter will read zero. 3. Boiler will trip by FSSS. 4. Turbine will trip through MFR.

KORBA SIMULATOR

300

5. Generator will start motoring. 6. Feeders will trip. 7. Mills, Fans, CEPs will continue to run. 8. Generator protection will not be available. 9. Generator breaker wil be operable from UCB. 10. DC pumps, fans will not be available. 11. HOTV, HORV will close. 12. Vacuum breaker will remain closed. 13. Field breaker will not be operable. 14. Extraction FCNRVs close. 15. MDBFPs can not be started if not already running. 16. TDBFPs AOPs will continue to run 17. SADCs will open full. 18. Deaerator overflow valve opens full 19. HP heaters protection will not be available. 20. Scanner air fan outlet damper and emergency dampers will remain stay put. 21. In ATRS panel DC AOP & DC JOP will have fault lamps glowing; if they were in service they will stop with red fault lamp. 22. Trim device will lose supply 23. Load shedding relay will lose supply (this relay has 220 v d.c supply but load Shedding solenoid is having 24 v supply) Emergency 7 : FAILURE OF + 24 V DC

CAUSE : REASON NOT KNOWN

Identification : All ATRs panel lamps will go off. Consequences :

KORBA SIMULATOR

301

1. EHC command will go to maximum, hence all control valves will open 100% load

will shoot up to maximum with CVs wide open condition. Tracking device will go to manual. UCB console EHC command NR PR will read zero. Hydraulic governor will become active.

2. ATRS panel supply fails. 3. All turbine protections will not be available. (Mechanical protections will be

available). 4. LP BP will not be available. 5. TSE fails 6. Hydraulic governor starting device motor control not available. 7. Lub oil temperature, HPCF temp., PW temp., coal gas temp., MAL 11, 12, 13, 14

temp. Controllers will remain stay put. 8. DC EOP will take start if the SLCs ON and lub oil pressure is less than 1.1

Kg/cm2. 9. JOP-3 will not start even if SLC is ON before the DC failure. 10. Excitation system pulse cards will be blocked and excitation collapses. Emergency 8 : -24V DC FAILURE

CAUSE : REASON NOT KNOWN

1. ATRS console lamps will remain healthy. 2. All turbine protection and extended turbine protection will remain healthy. 3. Remote control of all turbine side drives available. 4. LPBP not available. 5. Speeder gear and starting device UCB indication not available. 6. Lub oil temp., PW temp., cold gas temp., MAL-11, 12, 13, 14 and HPCF temp.

Controllers will remain stay put. 7. EHC command will go to maximum, HP & IP secondary oil pressure will be

maximum, UCB desk indication and EHC position, NR, PR, starting device, speeder

gear, indicator show zero.

KORBA SIMULATOR

302

8. EOP and JOP - 3 can be started from the console. NOTE : a) Confirm the starting of EOP. Trip the Turbine in case

restoration of - 24 v supply not possible b) Restoration of - 24 v supply : plunger coil will remain

ON & EHC will take original / less valve position Emergency 9 : UPS FAILURE

CAUSE : 1. FSSS trips the Boiler. 2. Turbine will trip on protection. 3. SADC will go full open. 4. Hydrastep indication will not be available. 5. DAS will be available. 6. Annunciation system will not be available. 7. ACS supply will not be available. 8. Total instrumentation supply will go OFF. 9. Burner tilt will be stay put, feedback indication will show zero as power to ACS is

not available. 10. Analog controller goes to zero. Emergency 10 : FD FANS LUB OIL PRESS LO

CAUSE : LUBE OIL DUPLEX FILTER CHOKED

1. DP across FD fan A/B lube oil filter becomes HI (> 1.2 kg/cm2) with a short delay 2. Annunciation "FD fan cont/lube oil press low" comes in (< 0.8 kg/cm2) 3. FD Fan A/B lube oil pressure becomes low

KORBA SIMULATOR

303

4. FD Fan A/B bearing temp monitor shows increasing value as the temperature

increases gradually with a time delay of 6-8 minutes 5. Annunciation "FD fan/motor bearing temperature high" comes on after sometime 6. FD fan lub oil pressure adequate permissive lamp will go off 7. "FD fan A/B Motor/fan brg temperature high" annuncitation comes in (> 85/95oC) 8. "FD fan Motor /fan brg temperature high high "comes in (> 90/105oC) NOTE : Prolonged operation may cause bearing temp. high enough

to trip FD fan. Emergency 11 :

ID FANS TRIP

CAUSE : LUBE OIL PRESSURE LOW DUE TO GRADUAL CHOKING OF DUPLEX FILTER

1. The ctrl oil pr drops below 1.8 Kg/sq cm. This causes the lead pump to take auto

start red ON lamp comes, green OFF lamp goes off 2. ID fan control/lub oil pr continues to drop, the permissive lamp hydraulic coupling

oil pr adequate goes off at pr less than 1.2 Kg/cm2) 3. ID fan vibration high alarm also comes 4. 'ID fan control oil pr low' annunciation appears (< 0.8 kg/cm2) 5. Running ID fan A HC oil pr low alarm appears 6. ID fan trips on hydraulic oil pr low protection bkr trip white lamp appears (< 0.5 kg/cm2) 7. 'ID fan tripped/start failure' annunciation appears 8. 'ID fan amps drop down to zero' 9. 'ID fan inlet vane and hydraulic coupling control is forced to manual yellow LED

glows 10. 'ID fan A inlet outlet damper GD 19, 22 starts closing and closed green lamp comes 11. Inlet/outlet damper full close permissive lamp glows

KORBA SIMULATOR

304

12. FD fan A trips on interlock white trip lamp glows 13. FD fan blade pitch control is forced to manual and auto release lamps starts

flickering as ID fan A ctrl is not on Auto 14. 'FD fan tripped/start failure' annunciation appears 15. FD fan discharge damper closes on auto Tripping of FD fan causes PA fan A to trip,

white trip light comes. 16. 'PA fan tripped/start failure' annunciation appears 17. PA fan amps drop down to zero 18. Co-ordinated control system (CCS) transfers to run back mode and initial pr mode.

Run back in operation facia glows 19. SPCM comes down to approx 60% and unit capability drops down

20. ID fan trip/FD fan trip facia glows on CCS insert 21. 'Unit run back in operation' annunciation appears 22. Boiler master output drops down to approx. 60% value 23. Fuel master controller output also drops down

24. Fuel flow and coal flow drops down 25. Air flow also drops down as a result 26. Furnace pr fluctuates widely 27. The HP control vlv opening reduces 28. Boiler pr/temp drops down NOTE : Loss of both ID fans at full load will cause a boiler trip.

KORBA SIMULATOR

305

Emergency 12 :

ABNORMAL ASH BUILD UP ON REHEATER PENDENT

CAUSE : CHANGE IN ASH CHARACTERISTICS. OF COAL BEING BURNED CAUSES ASH TO ACCUMULATE ON THE REHEATER TUBE SURFACES

1. Hot reheat temp. at IP turbine inlet decreases 2. The flue gas differential pr across reheater increases 3. MS/RH steam super heat low alarm appear (<480oC) 4. Final SH inlet and Eco. inlet flue gas temp. increases 5. RH Steam temperature control will reduce attemperation and/or raise burner tilt

to compensate for falling temp 6. SH temperature begins to increase 7. Flue gas pressure at RH inlet decreases 8. Flue gas press. at economiser inlet decreases 9. Flue gas pressure at RAPH inlet decreases 10. Furnace pressure increases slightly 11. ID fan control will go wide open and ID fan motor overload alarm appears 12. If Existing state is retained soot blowing should be done. 13. The flue gas differential pr across reheater decreases to normal value 14. Flue gas pressure at RH inlet gradually decreases to normal value 15. Flue gas press. at economiser inlet gradually increases to normal value 16. Flue gas pressure at RAPH inlet gradually decreases to normal value 17. Furnace pressure gradually decreases to normal value.

KORBA SIMULATOR

306

KORBA SIMULATOR

307

LIST OF MALFUNCTIONS

KORBA SIMULATOR

308

KORBA SIMULATOR

309

LIST OF MALFUNCTIONS

SL.NO. MNEMONIC DESCRIPTION

1. MAOl PRIMARY SCAPH STEAM INLET ISOLATION CLOSED

2. MAO2 SECONDARY SCAPH STEAM INLET ISOLATING VALVE

CLOSED

3. MAO3 PRIMARY / SEC RAPH LUB OIL PUMP TRIPS

4. MAO4 PRIMARY RAPH AIR MOTOR NOT AVAILABLE

5. MAOS SEC RAPH AIR MOTOR NOT AVAILABLE

6. MAO6 SCANNER AIR FILTER DIFF PRESS HI

7. MAO7 FD FANS LUBE OIL PRESS LO

8. MAOB ID FANS TRIP

9. MAO9 FD FANS TRIP

10. MAlO PA FANS TRIP

11. MAll ID FAN OUTBOARD BEARING TEMP HI

12. MA12 FD FAN OUTBOARD BEARING TEMP HI

13. MA13 PA FAN INBOARD BEARING VIBRATION HI

14. MA14 ID FAN INBOARD BEARING VIBRATION HI

15. MA1S PRIMARY AIR DAMPER AT RAPH OUTLET FAIL CLOSED

16. MA16 PULV COLD AIR DAMPER JAMMED

17. MA17 PLUGGED PRIMARY AIR HEATER

18. MA1B PLUGGED SEC AIR HEATER

19. MA19 AUX AIR DAMPER ADJUSTMENT TO COAL ELEVATION

FAULTY MODULATING

20. MA2O FSSS AC SUPPLY FAILURE

21. MA2l FD FAN DISCHARGE DAMPER FAIL CLOSED

22. MA22 ANY OF ELEVATION AUX AIR DAMPER NOT MODULATING

23. MA23 LEFT SIDE FURNACE PRESS TRANSMITTER FALSE READ

24. MA24 PRIMARY AIR HEATER MAIN DRNE MOTOR TRIP

25. MA2S SEC AIR HEATER MAIN DRNE MOTOR TRIP

26. MA26 AIR FLOW RUNBACK TO LESS THAN DEMAND

27. MA27 ID FAN INLET VANES FROZEN

28. MA28 LOSS OF SEAL AIR TO PULVERISER GROUP

KORBA SIMULATOR

310

SL.NO. MNEMONIC DESCRIPTION

29. MA29 AIR FLOW LESS THAN 30%

30. MA30 AIR FLOW MORE THAN 40% DURING START-UP

31. MA31 FURNACE WALLS BADLY SLAGGED

32. MA32 ASH BUILD UP IN ECONOMISER

33. MA33 PRIMARY AIR PRESS CTRL MALFUNCTIONING

34. MA34 FURNACE PRESS CONTROLLER MALFUNCTIONING

35. MA35 PRIMARY AIR HEATER FIRE

36. MA36 SEC AIR HEATER FIRE

37. MA37 AUX AIR DAMPER AIR SUPPLY FAIL

38. MA38 SCANNER AIR FAN (A) OR (B) TRIPS

39. MA39 PRIMARY AIR HEATER AIR MOTOR FAIL TO AUTO START

40. MA40 SEC AIR HEATER AIR MOTOR FAIL T0 AUTO START

41. MA41 PRIMARY /SEC AIR HEATER GUIDE/SUPPORT BEARING

TEMP INCREASING

42. MA42 FLAME INSTABILITY

43. MA43 FD FAIL CTRL FLUID PRESSURE LOW

44. MA44 FAIL OF ESP FIELD MORE THAN 40%

45. MA45 HI FURNACE PRESSURE (MANHOLES IN ESP)

46. MA46 FURNACE PRESSURE TRANSMITTER FAILURE

47. MA47 HI FURNACE PRESSURE (WATER SEAL BROKEN)

48. MA48 HI SUPERHEATER TUBE METAL TEMP

49. MA49 BOILER PURGE TIMER FAILURE

50. MA50 BOILER MASTER CONTROLLER FAILURE

51. MA49 BOILER PURGE TIMER FAILURE

52. MA50 BOILER MASTER CONTROLLER FAILURE

53. MA53 LOSS OF 220V DC TO FSSS

54. MA54 PULVERISER TRIP

55. MASS HEAVY OIL TRIP VALVE FAIL CLOSED

56. MA56 ALL PULVERISERS TRIP

57. MA57 FLAME SCANNER FAILURE

58. MA58 ELEV AB OIL GUN SCAVENGING VALVE STUCK OPEN

59. MA59 PULV HOT AIR GATE GETS CLOSED

KORBA SIMULATOR

311

SL.NO. MNEMONIC DESCRIPTION

60. MA60 PULV FAILS TO START

61. MA61 ID FAN HYDRAULIC COUPLING WORKING OIL TEMP

INCREASE

62. MA62 ANY PRIMARY RAPH STOPS

63. MA63 ANY SEC RAPH STOPS

64. MA64 PA FAN BLADE PITCH CTRL INOPERATIVE

65. MA65 MILL BREAKER NOT TRIPPING

66. MA66 ID FAN SCOOP TUBE INOPERATIVE

67. MA67 FD FAN BLADE PITCH NOT OPERATIVE

68. MA68 AF MAL SPARE L-16

69. MBOl BURNER TILT SYSTEM STUCK UP

70. MBO2 ABNORMAL ASH BUILD UP ON REHEATER PENDENT

71. MBO3 BURNER TILT POSITION DIFF AMONGST CORNERS

72. MBO4 BOILER WATER CIRC PUMP TRIPS

73. MBO5 WATER WALL TUBE LEAK

74. MBO6 STEAM DRUM PRESS TRANSMITTER FAIL LO

75. MBO7 REHEATER TUBE LEAK

76. MBO8 SEC SUPERHEATER TUBE LEAK

77. MBO9 SH ELECTROMATIC SAFETY VALVE FAIL OPEN

78. MBI0 RH ELECTROMATIC SAFETY VALVE FAIL OPEN

79. MBll ANY OF DRUM BLOW DOWN VALVE FAIL OPEN

80. MB12 AUX PRDS VALVE FAIL CLOSED

81. MB13 BURNER TILT CONTROLLER FAILS

82. MB14 BOILER WATER SILICA CONCENTRATION HI

83. MB15 ECONOMISER TUBE LEAK

84. MB16 RH SPRAY VALVE CONTROL FAILS OPEN

85. MB17 FAIL OF FINAL REHEATER TEMP CONTROLLER

86. MB18 SUPERHEATER STEAM OUT TEMP SWING

87. MB19 REHEATER STEAM OUT TEMP SWING

88. MB20 LOSS OF AUX STEAM .

89. MB21 LOSS OF SOOT BLOWING STEAM

90. BB22 HYDRAZINE FEED PUMP FAILS

KORBA SIMULATOR

312

SL.NO. MNEMONIC DESCRIPTION

91. MB23 LO SUPERHEATER TEMP

92. MB24 LO REHEATER TEMP

93. MB25 REHEATER SPRAY CONTROLLER FAILURE

94. MB26 LO STEAM PRESS

95. MB27 AUX STEAM PRESS LO

96. MB28 AUX STEAM TEMP HI

97. MB29 BCW PUMP STANDBY MOTOR CAVITY TEMP INCREASE

98. MB30 BCW PUMP TRIP, STANDBY NOT STARTING

99. MB31 BW MAL SPARE

100. MCOl VACUUM PUMP ISOLATING VALVE FAILS TO OPEN

101. MCO2 STANDBY VACUUM PUMP NOT AVAILABLE

102. MCO3 TRIPPING OR RUNNING VACUUM PUMP A/B

103. MCO4 VACUUM PUMP A/B 'ON' NOT AVAILABLE

104. MCO5 VACUUM PUMP ISV FAILS CLOSED

105. MCO6 HOTWELL NORM MAKE UP FLOW CTRL VALVE CLOSE

106. MCO7 HOTWELL NORM MAKE UP FLOW CTRL VALVE OPEN

107. MCO8 HOTWELL EMERGENCY MAKE UP FLOW CTRL VALVE

OPEN

108. MCO9 HOTWELL EMERGENCY MAKE UP FLOW CTRL VALVE

CLOSE

109. MCI0 HOTWELL MAKE UP PUMP TRIP

110. MCll CEP DISCHARGE SIDE ISOLATING VALVE STUCK

111. MC12 CEP MOTOR HAVE NO COOLING WATER FLOW

112. MC13 CEP MOTOR LOW BEARING TEMP START INCREASE

113. MC14 LOSS OF CONDENSER COOLING WATER puMp

114. MC15 GSC MIN RECIRCULATION VALVE FAIL OPEN MCO45

VALVE

115. MC16 CONDENSATE STORAGE TANK LO LEVEL SWITCH FAILS

116. MC17 HOTWELL LEVEL HI

117. MC18 CONDENSER TUBE LEAK

118. MC19 CONDENSER AIR LEAKAGE

119. MC20 CONDENSATE EXTRACTION PUMP TRIP

KORBA SIMULATOR

313

SL.NO. MNEMONIC DESCRIPTION

120. MC21 CONDENSER CIRC WATER DIFFERENTIAL PRESS HI

121. MC22 CEP RECIRCULATION VALVE FAIL CLOSED

122. MC23 GLAND STEAM CONDENSER TUBE LEAK

123. MC24 EXT STEAM SHUT OF VALVE TO HP HEATER FAIL TO

CLOSE POSITION

124. MC25 FW HEATER ALT DRAIN VALVE FAIL OPEN

125. MC26 FW HEATER NOR DRAIN VALVE FAIL CLOSED

126. MC27 DEAERATOR EXT STEAM VALVE CLOSED FALSELY (EX-

009)

127. MC28 EXT STEAM VALVE TO LP FW HEATER FAIL CLOSED

128. MC29 HP HEATER EXT STEAM BLOCK VALVE FAILS CLOSED

129. MC30 HP HEATER LEVEL VERY HI

130. MC31 SA OR sB HPH GROUP BYPASS STUCK UP AT 20%

131. MC32 TOTAL LOSS OF INSTRUMENT AIR PRESS

132. MC33 CS MAL SPARE 1-11

133. MEOl GENERATOR BEARING EXHAUST FAN NOT AVAIL

134. MEO2 GEN MAIN BREAKER FAILS TO CLOSE

135. MEO3 STATOR COOLING WATER LEAK INSIDE GENERATOR

136. MEO4 HYDROGEN COOLER TUBE LEAK

137. MEO5 LOSS OF HYDROGEN SEAL OIL PRESS

138. MEO6 GENERATOR HYDROGEN LEAK

139. MEO7 GENERATOR GAS TEMP HI

140. MEO8 LO STATOR COOLING WATER FLOW

141. MEO9 LOSS OF STATION POWER TO UNIT BUSES

142. MEI0 GENERATOR TRIP (PHASE TO PHASE OR PHASE TO

EARTH)

143. ME11 GENERATOR AVR FAILURE

144. ME12 SYS VOLTAGE DROP LO

145. ME13 LOSS OF GENERATOR EXCITATION

146. ME14 UNEQUAL GENERATOR PHASE LOADING

147. ME15 LOSS OF 41sV AC BUS

148. ME16 LOSS OF NORM FEED BKR TO AC/EMER BUS SECN

KORBA SIMULATOR

314

SL.NO. MNEMONIC DESCRIPTION

149. ME17 LO STATOR WATER RESISTANCE

150. ME18 HI STATOR CLG WTR TEMP

151. ME19 SEAL OIL LEAK INTO GENERATOR

152. ME20 AUTO SYNCHRONISER FAILS

153. ME21 GENERATOR SEAL OIL TEMP HI

154. ME22 MAIN POWER TRANSFORMER OIL TEMP HI

155. ME23 UNIT AUX TRANSFORMER FAILURE

156. ME24 LOSS OF EMERGENCY SUPPLY POWER

157. ME25 GENERATOR AVR OSCILLATE

158. ME26 AC SEAL OIL PUMP FAIL & DC SEAL OIL PUMP FAIL

159. ME27 STATOR CLG WTR PUMP TRIP (A/B)

160. ME28 220V DC BUS FUSE FLOWN

161. ME29 UPS SUPPLY FAILURE (+/- 24 V)

162. ME30 INSTRUMENT POWER SUPPLY TO UCB FAILURE

163. ME31 GENERATOR ROTOR TEMP HI

164. ME32 EXCITER CLG AIR TEMP HI

165. ME33 PRIMARY WTR/HYD COOLER DIFF TEMP LO

166. ME34 EXCITER DOME OPENS

167. ME35 GT TAP OUT OF SYNCHRONISM

168. ME36 ES MAL SPARE 1-5

169. MFOl FUEL MASTER CONTROLLER FAILURE

170. MFO2 HEAVY OIL HEADER PRESS LO

171. MFO3 COAL HANG UP AT MILL(A-H) INLET

172. MFO4 COAL FDR TRIP

173. MFO5 PULVERISER REDUCED CAPACITY

174. MFO6 FUEL FLOW RUNBACK TO LESS THAN DEMAND

175. MFO7 HEAVY OIL TEMP LO

176. MFO8 HEAVY OIL SUPPLY HEADER PRESS LO

177. MFO9 HI MILL OUTLET TEMP

178. MFI0 MILLS CHOKING

179. MFll LOSS OF SERVICE AIR PRESS

180. MF12 FS MAL SPARE 1-6

KORBA SIMULATOR

315

SL.NO. MNEMONIC DESCRIPTION

181. MTOl LPBYP GETS CHARGED SPURIOUSLY

182. MTO2 FALL OF CONDENSER VACUUM

183. MTO3 ALL ELECTRIC TRIP TAB DISABLED

184. MTO4 JACK OIL PUMP FAIL

185. MTO5 GLAND STEAM PR CONTROL VALVE CLOSED

186. MTO6 GENERATOR BEARING 1 BABBIT TEMP HI

187. MTO7 JACK OIL PUMP FAILS TO START

188. MTO8 ARTS STEP TIME EXCEEDED

189. MTO9 MOP FAILURE DUE TO COUPLING

190. MTI0 DM COOLING WATER PUMP MOTOR TRIP

191. MT11 LOSS OF GLAND STEAM VAPOR EXTRACTOR

192. MT12 LOSS OF TURB LUB OIL VAPOR EXTRACTOR

193. MT13 TURB AUX OIL PUMP TRIPS

194. MT14 LO SEC OIL PRESS TO IP CV

195. MT15 LOSS OF TURB GLAND SEALING STEAM

196. MT16 GLAND STEAM PRESS HI

197. MT17 ESV FAIL CLOSED

198. MT18 ISV FAIL CLOSED

199. MT19 TURBINE OVERSPEED TRIP DEVICE EARLY

200. MT20 HPCV MALFUNCTIONING

201. MT21 LOSS OF EXHAUST HOOD SPRAY

202. MT22 TURB MAIN OIL PUMP FAIL

203. MT23 LO TURB LUB OIL RESERVOIR LEVEL

204. MT24 HI TURB BEARING VIBRATION

205. MT25 ATRS SUBLOOP CTRL TURB DRAINS FAIL

206. MT26 LOSS OF TURBINE TSS POWER

207. MT27 BROKEN LAST STAGE TURBINE BLADES

208. MT28 MAIN TURBINE EHTC FAILS HI/LO

209. MT29 TURBINE AXIAL SHIFT HIGH

210. MT30 TURBINE OVERSPEED ON VERY HIGH LOAD REJECTION

211. MT31 BARRING GEAR VALVE STUCK CLOSED

212. MT32 HP TURBINE DIFFERENTIAL EXPANSION HIGH

KORBA SIMULATOR

316

SL.NO. MNEMONIC DESCRIPTION

213. MT33 TURBINE EOP FAILS TO AUTO START

214. MT34 TURBINE THRUST BEARING TRIP DEVICE SPUR TRIP

215. MT35 ESV SEAT DRAIN NOT OPEN DURING ROLLING

216. MT36 LOSS OF CONTROL POWER TO EHTC SYSTEM

217. MT37 MAIN TURB EHTC THROTTLE PRESS CONTROLLER FAIL

LO

218. MT38 TURB HP BYP PR VALVE FAILS CLOSED

219. MT39 LP BYP DESUPERHEATER VALVE FAILS CLOSED

220. MT40 WALL STRESS ANALYSER FAIL

221. MT41 TURB LP BYP FAIL CLOSED

222. MT42 TURB HP BYPVALVE FAIL TO OPEN ON DEMAND

223. MT43 TURB LUB OIL TEMP CTRL FAIL

224. MT44 ATRS CTRL POWER FAIL

225. MT45 ATRS SUB GROUP OIL SYS FAIL

226. MT46 LO VACUUM TRIP DEV FAIL TO FUNCTION

227. MT47 HP TURB CTRL VALVE MALFUNCTION (4 VALVES

228. MT48 IPTURB CTRLVALVE MALFUNCTION (4 VALVES)

229. MT49 TURB ECCENTRICITY HI

230. MT50 TURB LUB OIL PRESS LO

231. MT51 OVERSPEED TRIP DEV NOT RESET

232. MT52 LO VOLTAGE TO ATRS CTRL CUB

233. MT53 HP BYP OPENS

234. MT54 TURB LOAD START REDUCE

235. MT55 HP TURB EXHAUST TEMP HI

236. MT56 FIRE PROT OPERATED

237. MT57 EHTC REDUCE LOAD

238. MT58 TURB TRIP DUE TO TOP/BOTTOM DT

239. MT59 PR CONTROL OPR FROZEN

240. MT60 UNIT CMC MODE INEFFECTIVE

241. MT61 ARCW PUMPS A[6/B TRIP

242. MT62 ALL DMCW PUMPS TRIP

243. MT63 TS SPARE l-18

KORBA SIMULATOR

317

SL.NO. MNEMONIC DESCRIPTION

244. MWOl LO DRUM LEVEL

245. MWO2 HI BOILER DRUM LEVEL

246. MW03 SUPERHEATER ATTEMPERATION SPRAY BLOCK VALVE

(S83/S84) FAIL CLOSED

247. MWO4 LO SUPERHEATER TEMP

248. MWO5 HI REHEATER TEMP

249. MWO6 HI SUPERHEATER TEMP

250. MWO7 TURB DRIVEN BFP TRIP

251. MWO8 MDBFP-C BOOSTER PUMP COUPLING FAIL

252. MWO9 TDBFP COUPLING FAIL

253. MWI0 BFPT LUB OIL PRESS LO

254. MW11 FW HEATER TUBE LEAK

255. MW12 BFP RECIRCULATION VALVE FAIL CLOSED

256. MW13 BFP SPEED CONTROLLER FAIL DURING MDBFP IN

SERVICE

257. MW14 FLUCTUATING FW MASTER

258. MW15 LO RANGE FW REGULATING VALVE FAIL OPEN

259. MW16 MDBFP-C LOSS OF OIL PRESS

260. MW17 BFP HI BEARING VIBRATION

261. MW18 LOS OF BFP SUCTION

262. MW19 BFP RECIRCULATION VALVE FAIL OPEN

263. MW20 DEAERATOR OVERFLOW VALVE FAIL

264. MW21 DEAERATOR LEVEL CTRL VALVE FAIL OPEN

265. MW22 BFP TRIPS

266. MW23 BFP C HYD COUPLING OIL TEMP HI

267. MW24 DEAERATOR PRESS CTRL FAIL

268. MW25 LO RANGE FW CONTROLLER FAILS LO

269. MW26 TDBFP EHTC FAULT

270. MW27 TDBFP EHTC FAIL CLOSED

271. MW28 TDBFP FLOW INSUFFICIENT FOR FULL LOAD

272. MW29 MDBFP COOLING WATER MOTOR SIDE VALVE FAIL

CLOSED

KORBA SIMULATOR

318

SL.NO. MNEMONIC DESCRIPTION

273. MW30 BFP-C SCOOP TUBE INOPERATIVE

274. MW31 FW MAL SPARE 1-4

275. MXOl DAS KEYBOARD HANG UP

276. MXO2 ALARM CRT FAIL

277. MXO3 DAS SYS FAIL

278. MXO4 DAS MAL SPARE 1-4

Filename: volume2 Directory: D:\Backup-CD\Manuals\500MW Template: C:\Documents and Settings\SIMULATOR\Application

Data\Microsoft\Templates\Normal.dot Title: Subject: Author: Simulator Keywords: Comments: Creation Date: 1/1/2000 12:47 PM Change Number: 6 Last Saved On: 4/27/2006 11:47 PM Last Saved By: user Total Editing Time: 11 Minutes Last Printed On: 7/14/2006 11:46 AM As of Last Complete Printing Number of Pages: 318 Number of Words: 54,079 (approx.) Number of Characters: 270,396 (approx.)