Boiler IN&PR1.pptx

RC FEEDER INTERLOCK & PROTECTION 1

INDIABULLS POWER LIMITED

BOILER-PROTECTION & INTERLOCK

2RC FEEDER INTERLOCK & PROTECTION

PROTECTION& INTERLOCKCLASSIFICATION OF BOILER

PROTECTIONS & INTERLOCKS

BOILER AUXILIARIES INTERLOCK & PROTECTION

This system takes care of sequence of starting protection & interlock of boiler auxiliaries like 1) ID fans2) FD fans3) PA fans4) APH5) MILL6) RC FEEDER7) REHEATER Protection

FURNANCE SAFEGAURD SUPERVISORY SYSTEM(FSSS)

This system takes care of interlocks required for starting, supervising the operating & safe shutdown of the equipments connected with fuel firing system like1) Purge Interlock2) LOTV control & supervision3) HOTV control & supervision4) Pulveriser interlocks5) SADC- on/off & supervision6) Flame Intelligence & checking7) Boiler flame failure protection8) Boiler Trip protection


Furnace safeguard Supervisory System

It is designed to ensure the execution of safe, orderly operating sequence in

start up and shutdown of fuel firing equipments and to prevent error of

omission and commissioning in following such a safe operating procedure.

• FSSS system supervises, controls and monitors the preparation,

distribution and admission of fuel & air into the furnace and execution

and enforcement of pre-established safe firing procedure.

• The FSSS provides permissive interlocks only to ensure safe start up

sequence of equipment.

Introduction to FSSSFurnace Safeguard Supervisory System(FSSS)


FSSS is designed to perform the following functions:

• Prevent any fuel firing unless a satisfactory furnace purge sequence has

first been completed.

• Prevent start-up of individual fuel firing equipment unless certain permissive

interlocks have first been satisfied.

• Monitor & control the proper sequence (Manual or Automatic) during start-

up and shutdown of fuel firing equipment.

• Make continued operation of fuel firing equipment subject to certain safety

interlocks remaining satisfied.

• Provide status feedback to the operator and in some cases, to the unit

control system.

• Provide flame supervision when fuel firing equipment is in service and affect

a fuel trip upon certain adverse operating conditions.

• Initiate a fuel trip when certain abnormal operating conditions exist.

5

FSSS’s Operational Function:1) FURNACE PURGE SUPERVISION.

2) LIGHT OIL ON/OFF CONTROL & SUPERVISION.

3) HEAVY OIL ON/OFF CONTROL & SUPERVISION.

4) PULVERISER CONTROL & SUPERVISION.a. Pulveriser discharge valve control.b. Pulveriser ignition permissive.c. Pulveriser ready permissive.d. Pulveriser on/off control.e. Hot air gate open/close controlf. Feeder start/stop control.

5) SADC - ON/OFF CONTROL & SUPERVISION.

6) FLAME SCANNER INTELLIGENCE & CHECKING.a. Scanner air fan control.b. Flame scan output indication.c. Flame failure trip.

7) BOILER TRIP PROTECTIONRC FEEDER INTERLOCK & PROTECTION


FSSS’s Operational Function:• Furnace Purge

Before any fuel firing can take place, (initially or after a boiler trip) a

successful furnace purge cycle must be completed. To start furnace purge

cycle

• Establish AC/DC supply to FSSS equipments.

• Bring normal water level in drum.

• Take at least one ID&FD fans in service.

• Establish airflow between 30% to 40% of MCR

PURGE READY

AND

Press “START PURGE” button

START PURGEPURGING

5 minute count down timer ON


FSSS’s Operational Function:• Furnace Purge

If PURGE READY signal is not available, then check the following

conditions are satisfied• Light oil trip valve is proven closed.• Light oil nozzle valves are proven closed.• Heavy oil trip valve is proven closed.• Heavy oil nozzle valves are fully closed.• All PA fans are off.• All feeders are off.• All hot air gates are fully closed.• All the flame scanners show “NO FLAME”• No boiler trip command is present.• Airflow between 30% & 40% MCR.• All auxiliary dampers are modulating.


FSSS’s Operational Function:LIGHT OIL TRIP VALVE CONTROL(LOTV)

• Conditions to be fulfilled to open LOTV after successful purging Light oil supply pressure is adequate All LO nozzle valve proven closed in AB elev

•Conditions leading to close LOTV automaticallyMFT

Any Light oil nozzle valve not closedLight oil header pressure very low

Any light oil nozzle valve not closedAtomizing air pressure very lowNo light oil Start/Stop in Elevation AB

LOTV

FM To AB elevation burners

AIR

LDO LOFCV

Tripping command to close LOTVand or

and

AND “LOTV OPEN”

Permissive ok


FSSS’s Operational Function:HEAVY OIL TRIP VALVE CONTROL(HOTV)

• HOTV opening conditionsHORTV is fully openHOTV close command is not present

All heavy oil nozzle valves are closedNo MFT condition is presentHO supply pressure is adequateHO supply temperature is adequateHOTV close command is not present

HFO

Return line to tanks

FM To AB,CD,EF elevation burnersHOTV

HOFCV

SteamHORTV

“HOTV OPEN” permissive satisfied

and

or

and

and


FSSS’s Operational Function:HEAVY OIL TRIP VALVE CONTROL

• HOTV closing conditions

Master fuel trip

HO Recirculation valve is not closed

If any of the conditions exist for more than 5 sec

Atomizing steam pressure very low

No HO start or stop in any elevation

Any HO nozzle valve not closed

HO header pressure very low


HO header temperature very low


*Also HO commanded to close under loss of 220VDC

CLOSE command to HOTV

or

and

and

and

and

or

11

PULVERISER CONTROLPULVERSISER DISCHARGE VALVE CONTROL:

•The pulveriser discharge valve can be opened manually by depressing the push-button on the console insert. •The valve can be manually closed by the push-button on the console insert only when the pulveriser is off. The corresponding indications are available on the console insert as Red and Green lamps for open and close positions respectively

FSSS’s Operational Function:

RC FEEDER INTERLOCK & PROTECTION

12

PULVERISER CONTROL PULVERISER IGNITION PERMIT:Prior to starting any feeder, the feeder ignition energy must be adequate to support coal firing. This is accomplished all 6 elevations as follows:PULVERISER "A“A minimum of 3 of the 4-elevation “AB“ oil nozzle valves proven open Boiler loading is greater than 30%Feeder “B” is in service at greater than 50% loading

PULVERISER "B“A minimum of 3 of the 4-elevation “AB“oil nozzle valves proven open Boiler loading is greater than 30% Feeder “A” is in service at greater than 50% loading.Feeder “C” is in service at greater than 50% loading.

PULVERISER "C" A minimum of 3 of the 4-elevation “CD“oil nozzle valves proven open Boiler loading is greater than 30%Feeder “B” is in service at greater than 50% loadingFeeder “D” is in service at greater than 50% loadingA minimum of 3 of the 4-elevation “AB“oil nozzle valves proven openFeeder “B” is in service at greater than 50% loading.


Permit signal to start PULVERISER A

andor

Permit signal to start PULVERISER Cand or

or

and

Permit signal to start PULVERISER Band or

or


13

PULVERISER "D" A minimum of 3 of the 4-elevation “CD“ oil nozzle valves proven open. Boiler loading is greater than 30%Feeder “C” is in service at greater than 50% loading.Feeder “E” is in service at greater than 50% loading.

PULVERISER "E“A minimum of 3 of the 4-elevation “EF“oil nozzle valves proven open Boiler loading is greater than 30%Feeder “D” is in service at greater than 50% loading.Feeder “F” is in service at greater than 50% loading. A minimum of 3 of the 4-elevation “CD“ oil nozzle valves proven openFeeder “D” is in service at greater than 50% loading.

PULVERISER "F“A minimum of 3 of the 4-elevation “EF“oil nozzle valves proven open. Boiler loading is greater than 30%Feeder “C” is in service at greater than 50% loading


Permit signal to start PULVERISER D


and or

or

Permit signal to start PULVERISER E

oror

and

and

Permit signal to start PULVERISER F

or

and

PULVERISER CONTROL PULVERISER IGNITION PERMIT:

14

PULVERISER CONTROLHOT AIR GATE(HAG) CONTROL:

• CONDITIONS FOR HAG OPENPULVERISER ON

PULVERISER AUTO START

MANUAL MODEOPEN HAG FROM PUSH BOTTON

• CONDITIONS FOR HAG CLOSE

CLOSE HAG COMMAND EXIT>30 SECSPULVERISER OFFLOSS OF 24V DC IN ELEVATION



orCLOSE COMMAND TO HOT AIR GATE

OPEN COMMAND TO HOT AIR GATEor

and

and

15


MASTER FUEL TRIP

• If some abnormal condition occurs(like less than 30% air ), Master Fuel Trip

Relay acts and ensures the closure of Heavy Oil Trip valve (HOTV) and all

light Oil Nozzle Valves (LONV), thus cutting off total oil supply.

• Thus MFT ensures a safe shut down of the boiler in case of any abnormal

conditions in boiler/ furnace.

• It also ensures the stopping of all pulverizer systems and Primary Air (PA)

fans, cutting off total coal supply to boiler. The various abnormal operating

conditions under which Master Fuel Trip occurs are as follows:-


16


MASTER FUEL TRIP CONDITIONS

1. Drum level very low > 5 seconds.

2. Drum level very high > 10 seconds.

3. Both FD Fans off.

4. Both ID Fans off.

5. Air flow is less than 30% (318.03Tons/Hr )

6. Furnace pressure very low.

7. Furnace pressure very high.

8. Loss of all fuel trip.

9. Unit flame failure trip.

10. Loss of 220V DC for more than 2 seconds

11. Less than fire ball and loss of 110V AC at any elevation in service.

12. Loss of Reheater protection.

13. Both emergency trip Push Buttons pressed (Operator initiated boiler trip).

14. Spare trip.


17

FSSS’s Operational Function:MASTER FUEL TRIP CONDITIONS

When MFT acted, simultaneous impulses shall be given for :-

1)Closing all the nozzle valves (LONV/HONV) and trip valves (LOTV/HOTV).

2)All fuel inputs are stopped by tripping all the mills.

3)Closing all hot air gates(HAG).

4)Tripping all the feeders.

5)All fuel air dampers are opened 100% and transferred to manual.

6) All auxiliary air dampers are opened 100% and transferred to manual.


18


•During light up and until any main fuel (coal) is in service at a fire condition, the flame scanners do not take part in the overall flame failure protection system.

•A fire ball condition is established for coal firing when either or both the adjacent feeders are proven

.AND. 2 out of 4 fireball scanners show flame.


FLAME SCANNER INTELLIGENCE AND CHECKING SCANNER AIR FLOW CONTROL FLAME SCANNER OUTPUT INDICATION FLAME FAILURE PROTECTION



Two scanner air fans (1 AC main + 1 DC stand-by) are provided for the unit.

1)AC scanner fan will automatically start if following condition are fulfilled:

2)DC scanner fan will automatically start:

3)In the event of 24VDC failure or all FD fans off, scanner’s atmosphere emergency suction damper will open(at normal condition suction from FD discharge)

FLAME SCANNER INTELLIGENCE AND CHECKING SCANNER AIR FAN CONTROL

AC scanner fan does’t start >5secs

AC scanner fan trips

Low DP across Furnace to Scanner Duct> 10 secs

OR

LOGIC

Start cmd to DC Scanner Fan

AND LOGIC

AC Scanner Fan will automatically start

After completion of PURGE

ON MFT



For AB elevation

Feeder B proven

Elv. AB 2/4 FB scanner show flame

Feeder A proven

*Same similar flame indication logic for BC,CD,DE,EF

FLAME SCANNER INTELLIGENCE AND CHECKING FLAME SCANNER OUTPUT INDICATION

AND

LOGICOR

LOGIC

ELE AB FLAME

Arming signal to “FLAME

FAILURE TRIP PROTECTION”

>2secs


FSSS’s Operational Function:FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION:

•An elevation voting for "No Flame" condition is as described below for the respective coal and oil elevations.

ELEVATION “A”Feeder “A” is not provenElevation AB- 3/4 Fireball scanners shows no flameElevation AB HO/LO- 2/4 nozzle valves not openElevation AB started and loss of 110V AC power

ELEVATION “B”Feeder “B” is not proven. Elevation AB- 3/4 Fireball scanners shows no flameElevation AB HO/LO- 2/4 nozzle valves not open Elevation AB started and loss of 110V AC powerElevation “BC” 3/4 fire ball scanners show no Flame

ELEVATION “C”Feeder “C” is not proven.Elevation CD- 3/4 Fireball scanners shows no flameElevation CD HO- 2/4 nozzle valves not open.Elevation CD started and loss of 110V AC power.Elevation “BC”- 3/4 fire ball scanners show no Flame

FSSS

and or

ELEVATION BVOTED NO FLAME

andor

and

ELEVATION CVOTED NO FLAME

and

and

or

ELEVATION AVOTED NO FLAME

and or



ELEVATION “D”Feeder “D” is not provenElevation CD 3 out of 4 Fireball scanners shows no flameElevation CD HO 2 out of 4 nozzle valves not openElevation CD started and loss of 110V AC powerElevation “DE” 3 out of 4 fire ball scanners show no Flame

ELEVATION “E”Feeder “E” is not provenElevation EF 3 out of 4 Fireball scanners shows no flameElevation EF HO 2 out of 4 nozzle valves not openElevation EF started and loss of 110V AC powerElevation “DE” 3 out of 4 fire ball scanners show no Flame

ELEVATION “F”Feeder “F” is not proven.Elevation EF 3 out of 4 Fireball scanners shows no flameElevation EF HO 2 out of 4 nozzle valves not openElevation EF started and loss of 110V AC power

ELEVATION DVOTED NO FLAME

andor

and

ELEVATION E VOTED NO FLAME

and

and

or

ELEVATION F VOTED NO FLAME

and or

FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION(cont):


FSSS’s Operational Function:FLAME SCANNER INTELLIGENCE AND CHECKING FLAME FAILURE PROTECTION(cont):

Any of feeder proven

Elv. F voted no flame

Elv. E voted no flame

Elv. D voted no flame

Elv. C voted no flame

Elv. B voted no flame

Elv. A voted no flame

ANDLOGIC

UNIT FLAME FAILURE TRIP

SIGNAL

All elevation voting for “No Flame" as described above will cause a unit trip on Flame Failure trip, provided the flame failure circuit is armed. (Unit Flame failure Trip circuit is armed 2 seconds after any coal elevation is put into service. i.e. any feeder proven

24

SADC CONTROLFSSS’s Operational Function:


Secondary Air Damper Control includes both auxiliary & fuel air Damper control

25



Auxiliary air damper position at above & below 30% boiler load.

Note:During furnace purge, all auxiliary air dampers are in 100% open condition

Auxiliary Air Damper PositionBoiler load<30%(opening) Boiler load>30%(closing)

1) When boiler load below 30% MCR all auxiliary air dampers are opened 100%

2) Furnace to Wind box DP is maintained approximately 40mmwc

1) Auxiliary air dampers associated with non service elevation will close from top to bottom with 10secs time sequence

2) Furnace to Wind box DP is increased with respect to oil header pressure.

SADC CONTROLA) Auxiliary Air Damper Control:

26

SADC CONTROLA) Auxiliary Air Damper Control:



1)Conditions leading to Manual control & automatically open of Auxiliary Air Damper:

All ID fans OFF

All FD fans OFF

MFT

Loss of 24V DC

2) Conditions leading to Manual control :

DP trans. deviation very high

Failure of selected DP trans.

Furnace to Wind Box DP very

High >240mmwc

OR

Logic

Commanded to 100% open

+ Manual control

OR

LogicThrown to

Manual control

27



Fuel air dampers are modulated with respect to feeder rate

Feeder ON signal

Feeder OFF signal

Note:During purging all fuel air dampers are in 100% open position.

SADC CONTROLB) Fuel(Coal) Air Damper Control:

50 seconds > OPEN cmd to fuel air damper

50 seconds > CLOSE cmd to fuel air damper

28



1)Conditions leading to Manual control & automatically open of Fuel Air Damper:

All ID fans OFF

All FD fans OFF

MFT

Loss of 24V DC

2) Conditions leading to Manual control :

Feeder rate signal failed

open cmd from FSSS

close cmd from FSSS

OR

Logic

Commanded to 100% open

+ Manual control

OR

LogicThrown to

Manual control

SADC CONTROLB) Fuel(Coal) Air Damper Control:

29



C) Over fire Air Damper Control:

Over fire air dampers are used to control SOx & NOX

1. Lower Over fire air damper will open when boiler load >50% MCR

2. Upper Over fire air damper will open when boiler load>75%MCR



31

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTION

Conditions existing when the unit is shutdown and prior to starting of ID Fans:

1)ID fan A & B are OFF.

2)Regulating dampers of fans A & B are fully open.

3)Inlet gates of ID fans A & B open.

4)Outlet gates of ID fans A & B open.

5)The regulating dampers and hydraulic coupling will be on manual control

during shutdown and impulse from furnace draft control to

regulating dampers of ID fans disconnected.


32

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan A (ID Fan B is OFF):

A) ID fan A shall be prohibited from starting till the following conditions are satisfied:

1)Regulating dampers of ID FAN - A in minimum position.

2)Hydraulic coupling scoop tube for ID FAN - A in minimum position &

manual.

3)Outlet gate of ID FAN – A closed.

4)Intel gate of ID FAN – A closed.

5)ID FAN - A’s fan & motor bearing temperature not very high.

6)Motor winding temperature not very high.

7)One of APH is running with its inlet & Outlet dampers in open position.

8)Lube oil permissive satisfied(any LOP on & pressure >0.8 ata).

9)Hydraulic coupling of ID Fan-A’s oil level O.K and cooler ready for

operation.

10)Flue gas path available(dampers across APH,ESP & FD fan o/l damper

open).


33

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan A (ID Fan B is OFF):

B) When ID fan A is started , impulses shall be given for :-

1)Opening the inlet gate of ID Fan- A after the motor reaches rated speed.

2)Connecting the regulating dampers/scoop tube control of ID Fan – A to

auto control

3)Closing the inlet gate and the outlet gate of ID Fan – B and bring the

regulating dampers/scoop tube control to minimum position

4) Permission to start either FD Fan – A or B

*Same similar interlocks for Starting ID Fan B (ID Fan A is OFF)


34

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan A (ID Fan B is OFF):

A) ID fan A will trip automatically under following conditions:-

OR LOGIC

ID fan A’s fan bearing temp too high>90’c >10secs

ID fan A’s motor bearing temp too high>90’c >10secs

ID fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

FD fan’s tripping interlock to ID fan

ID fan A’s motor winding temp too high>130’c >10secs

ID fan A ON & its I/T gate closed>30secs

ID fan A’s working oil temp very high>110’c>2secs

ID fan A’s motor protection, eg- earth fault, short-circuit

Trip signal to ID fan A


35

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan A (ID Fan B is OFF):

B) When ID fan A trips simultaneous impulse will be give for :-

1) Tripping signal to working FD fan.

2) Tripping signal to Boiler through FSSS.

3) Disconnecting the impulse from auto control to regulating damper and

Hydraulic coupling control.

4) Opening of inlet & outlet gate of ID fan B.

5) Commanded to wide open of regulating damper of ID A & B.

*Same similar interlocks for ID Fan B(ID Fan A is OFF)


36

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan B (ID Fan A is ON):

A) ID fan B shall be prohibited from starting till the following conditions are satisfied:

1)Regulating dampers of ID FAN - B in minimum position.

2)Hydraulic coupling scoop tube for ID FAN - B in minimum position &

manual.

3)Outlet gate of ID FAN – B closed.

4)Intel gate of ID FAN – B closed.

5)ID FAN - B’s fan & motor bearing temperature not very high.

6)ID FAN - B’s Motor winding temperature not very high.

7)Lube oil permissive satisfied(any LOP on & pressure >0.8 ata).

8)ID Fan-B’s Hydraulic coupling oil level O.K.


37

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONStarting of ID Fan B (ID Fan A is ON):

B) When ID fan B is started (ID fan A is ON), impulses shall be given for :-

1)Opening the inlet gate of ID Fan- B after the motor reaches rated speed.

2)Connecting the regulating dampers/scoop tube control of ID Fan – B to

auto control

3)Permission to start another FD Fan.

*Same similar interlocks for Starting ID Fan A (ID Fan B is ON)



BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan B (ID Fan A is ON):

A) ID fan B will trip automatically under following conditions:-

OR LOGIC

ID fan B’s fan bearing temp too high> 90’c >10sec

ID fan B’s motor bearing temp too high> 90’c >10sec

ID fan B’s fan (12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

FD fan’s tripping interlock to ID fan

ID fan B’s motor winding temp too high130’c>10sec

ID fan B ON and I/T gate not open>30sec

ID fan B’s hydraulic coupling lub oil pressure very low<0.6Bar

ID fan B’s hydraulic coupling working oil temp very high>110’c for 2sec

Trip signal to ID fan B

ID fan B’s motor protection, eg- earth fault, short circuit

39

BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S INTERLOCKS & PROTECTIONTripping of ID Fan B (ID Fan A is ON or vise versa):

B) When ID fan B trips simultaneous impulse will be give for :-

1) Disconnecting the impulse from auto control to regulating damper and

Hydraulic coupling control.

2) Bring the regulating damper of ID fan B to minimum position.

3) Bring the hydraulic coupling scoop tube position to minimum.

4) Commanded to close inlet & outlet gate of ID fan B.

5) Tripping signal to one working FD fan( 2 FD fans working).

6) Initialization of Partial load relay to reduce boiler load to 60%MCR.

*Same similar interlocks for ID Fan A(ID Fan B is ON)



BOILER AUXILIARIES INTERLOCK & PROTECTIONID FAN’S LUBRICATION OIL PUMPS:

• There are 2x100% LOPs(1W, 1S) are provided for each ID fans

LOPs will automatically start under following condition(when ID A is ON):

LOP A or B will automatically stop under following condition(when both LOPs are ON):

TRIP CMD TO ANY ONE LOP A or B

LOP A tripped >30secs

LOP A is ON & pressure<0.6ATA >30secs

ORLOGIC

START CMD TO LOP B

LOP B tripped

LOP B is ON & pressure<0.6ATA

ORLOGIC

START CMD TO LOP A>30secs

>30secs

LOP B ON

Lub Oil pressure>0.8ATA

>5secs

LOP A ON AND

LOGIC

*same similar interlocks for ID fan B’s LOPs


BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTION

Conditions existing when the unit is shutdown and prior to starting of FD Fans:

1)FD fan A & B are OFF

2)FD fan A & B blade pitch in maximum position.

3)FD fan blade pitch control disconnected.

4)Lub Oil pumps of FD fans off.

5)Outlet dampers are fully open.

42

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan A (FD Fan B is OFF):

A)FD fan A shall be prohibited from starting till the following conditions are satisfied:

1)ID fan either A or B is ON.

2)FD FAN – A blade pitch control in minimum position.

3)Outlet damper of FD FAN – A closed

4)Intel gate of FD FAN – A open

5)FD FAN - A’s fan & motor bearing temperature not very high

6)Motor winding temperature not very high

7)FD fan’s Lube oil permissive satisfied(any LOP on & pressure >13bar)


43

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan A (FD Fan B is OFF):

B) When FD fan A is started (FD fan B is off), impulses shall be given for :-

1)Opening the outlet gate of FD Fan- A after the motor reaches rated speed.

2)Outlet damper of FD Fan – B to close & impeller blades of FAN-B to be

driven to minimum position.

3)Connecting the blade pitch control of Fan – A to auto control.

*Same similar interlocks for Starting FD Fan B (FD Fan B is OFF)


44

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan A (FD Fan B is OFF):

A) FD fan A will trip automatically under following conditions:-

OR LOGIC

FD fan A’s fan bearing temp too high> 105’c >10sec

FD fan A’s motor bearing temp too high> 110’c >10sec

FD fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

ID fan trips

FD fan A’s motor winding temp too high> 130’c >10sec

FD fan A ON and its O/T gate not open>120sec

Trip signal to FD fan A

FD fan A’s motor protection, eg- earth fault, short circuit


45

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan A (FD Fan B is OFF):

B) When FD fan A trips simultaneous impulse will be give for :-

1) Disconnecting the blade pitch of FD fan A & B to the maximum.

2) Opening the outlet damper of fan B.

3) To open the scanner air emergency suction damper.

4) Tripping signal to Boiler through FSSS

5) The outlet damper of FD fan A shall remain open.

*Same similar interlocks for FD Fan B(FD Fan A is OFF)


46

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan B (FD Fan A is ON):

A)FD fan B shall be prohibited from starting till the following conditions are satisfied:

1)Two ID fans should be ON.

2)FD FAN – B blade pitch control in minimum position.

3)Outlet damper of FD FAN – B is in closed position.

4)FD FAN - B’s fan & motor bearing temperature not very high

5)Motor winding temperature not very high

6)FD fan’s Lube oil permissive satisfied(any LOP on & pressure >3BAR)


47

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONStarting of FD Fan B (FD Fan A is ON):

B) When FD fan B is started (FD fan A is on), impulses shall be given for :-

1)Opening of outlet damper of FD Fan- B after the motor reaches rated

speed.

2)Connecting the blade pitch control of Fan – B to auto control.

*Same similar interlocks for Starting FD Fan A (FD Fan B is OFF)RC FEEDER INTERLOCK & PROTECTION

48

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan B (FD Fan A is ON):

A) FD fan B will trip automatically under following conditions:-


OR LOGIC

FD fan B’s fan bearing temp too high> 105’c >10sec

FD fan B’s motor bearing temp too high> 110’c >10sec

FD fan B’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

Any one or both ID fan trips

FD fan B’s motor winding temp too high> 130’c >10sec

Trip

signal to FD fan B

FD fan B’s motor protection, eg- earth fault, short circuit

FD fan B ON and its O/T gate not open>120sec

49

BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S INTERLOCKS & PROTECTIONTripping of FD Fan B (FD Fan A is ON):

B) When FD fan B trips simultaneous impulse will be give for :-

1) Disconnecting FD fan B the blade pitch control from auto.

2) Bringing the FD fan B blade pitch control to minimum position.

3) Closing the outlet damper of Fan B.

4) Initiation of partial load relay for 60% MCR

*Same similar interlocks for FD Fan A trips (FD Fan B is OFF)



BOILER AUXILIARIES INTERLOCK & PROTECTIONFD FAN’S LUBRICATION OIL PUMPS:

There are 2x100% LOPs(1W, 1S) are provided for each FD fans

LOP will automatically start under following condition(when FD A is ON):

LOP will automatically stop under following condition(when both LOPs are ON):

*same similar interlocks for FD fan B’s LOPs

ORLOGIC

START CMD TO LOP BLOP A tripped >30secs

LOP A is ON & pressure<9BAR >60secs

LOP B tripped

LOP B is ON & pressure<9BAR

ORLOGIC


>30secs

LOP B ON

Lub Oil pressure>13BAR

>5secs TRIP CMD TO ANY ONE LOP A or B

LOP A ON AND

LOGIC


BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTION

Conditions existing when the unit is shutdown and prior to starting of PA Fans:

1)PA fan A & B are OFF

2)PA fan A & B blade pitch in maximum position.

3)PA fans blade pitch control disconnected.

4)Lub Oil pumps of PA fans off.

5)Outlet dampers are fully open for PA Fan A & PA Fan B.

52

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan A (PA Fan B is OFF):

A)PA fan A shall be prohibited from starting till the following conditions are satisfied:

1)Either FD fan A or B is ON.

2)PA FAN – A blade pitch control in minimum position.

3)Purge completed

4)PA FAN - A’s fan & motor bearing temperature not very high

5)Motor winding temperature not very high.

6)APH should be in service with one gas & air inlet and outlet damper

opened.

7)PA fan’s Lube oil permissive satisfied(any LOP on & pressure >0.8 ata)


53

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan A (PA Fan B is OFF):

B) When PA fan A is started , impulses shall be given for :-

1)Opening the outlet damper of PA Fan- A.

2)Connecting the blade pitch control of PA Fan – A to auto control

3) Bringing the blade pitch of PA fan B to minimum position.

4)Closing of outlet damper of PA fan B

5) Permission to start 3 lower coal elevations through FSSS

*Same similar interlocks for Starting PA Fan B (PA Fan A is OFF)


54

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan A (PA Fan B is OFF):

A) PA fan A will trip automatically under following conditions:-


OR LOGIC

PA fan A’s fan bearing temp too high> 105’c >10sec

PA fan A’s motor bearing temp too high> 90’c >10sec

PA fan A’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

Both FD fan trips

PA fan A’s motor winding temp too high>120’c >10sec

Trip

signal to PA fan A

PA fan A’s motor protection, eg- earth fault, short circuit

MFT acted

PA fan A ON and its O/T gate not open>120sec

55

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan A (PA Fan B is OFF):

B) When PA Fan B trips simultaneous impulse will be give for :-

1) Disconnecting the blade pitch control from auto.

2) Bringing the PA fan A blade pitch control to minimum position.

3) Closing the outlet damper of PA Fan A.

4) Tripping all the operating mills (through FSSS)

*Same similar interlocks for PA Fan B(PA Fan A is OFF)


56

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan B (PA Fan A is ON):

A) PA fan B shall be prohibited from starting unless following condition are satisfied

1)Both FD fans ON.

2)Blade pitch control of PA fan B in min. condition.

3)PA fan B & Motor bearing temp not very high(<90oC)

4) Motor winding temp. not very high(<80oC).

5)Both APH are running with their gas and air inlet and outlet dampers

opened

6)Lube oil permissives satisfied

*Same similar interlocks for Starting PA Fan B (PA Fan A is ON)


57

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONStarting of PA Fan B (PA Fan A is ON):

B) When PA fan B is started (PA fan A is ON), impulses shall be given for :-

1)Opening the outlet damper of PA fan B after the motor ON (TD = 30 sec.).

2)Connecting the damper control of PA fan B to auto control.

3)Permission to put in service remaining coal elevation through FSSS.

*Same similar interlocks for Starting PA Fan A (PA Fan B is ON)


58

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan B (PA Fan A is ON):

A) PA fan B will trip automatically under following conditions:-


PA fan B ON and its O/T gate not open>120sec

OR LOGIC

PA fan B’s fan bearing temp too high> 105’c >10sec

PA fan B’s motor bearing temp too high> 90’c >10sec

PA fan B’s fan(12.6mm/sec) or Motor(9.6mm/sec) vibration too high>10sec

Both FD fans OFF

PA fan B’s motor winding temp too high>120’c >10sec

Trip

signal to PA fan B

PA fan B’s motor protection eg- earth fault, short circuit

MFT acted

59

BOILER AUXILIARIES INTERLOCK & PROTECTIONPA FAN’S INTERLOCKS & PROTECTIONTripping of PA Fan B (PA Fan A is ON):

B)When PA Fan B trips simultaneous impulse will be give for :-

1) Disconnecting the blade pitch control of PA fan B from auto.

2) Bringing the PA fan B blade pitch control to minimum position.

3) Closing the outlet damper of PA Fan B.

4) Initiation of partial load relay for 60% MCR

*Same similar tripping interlocks for PA Fan A(PA Fan B is ON)




• There are 2x100% LOPs(1W, 1S) are provided for each PA fans

LOP will automatically start under following condition(when PD A is ON):

LOP will automatically stop under following condition(when both LOPs are ON):

*same similar interlocks for PA fan B’s LOPs

ORLOGIC

START CMD TO LOP BLOP A tripped >30secs

LOP A is ON & pressure<13BAR >30secs

LOP B tripped

LOP B is ON & pressure<13BAR

ORLOGIC


>30secs

LOP B ON

Lub Oil pressure>20BAR

LOP A ON AND

LOGIC>5secs TRIP CMD TO ANY ONE LOP A or B

PA FAN’S LUBRICATION OIL PUMPS:


BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTIONConditions existing when the unit is shutdown and prior to starting of APH:

1)All AHs are off (both electric motor and air motor).

2)The inlet and outlet dampers of flue gas path, Secondary Air path,

Primary Air path are in full open condition.

Starting Air Heater – A (Air Heater – B is OFF)

One electric motor and one air motor have been provided for APH drive system.3) Air Heater – A electric main motor is started if the sump oil temperature

of the bearings measured through RTD is less than 70oC

4)Impulse shall be given for closing of the inlet and outlet dampers for air & gas side of Air Heater B which is off

*same similar interlocks for starting APH – B(APH – A is OFF)

62

BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTIONTripping of APH-A (APH-B is OFF):

1)APH electric motor fault.2)Whenever the sump oil temperature of support/guide bearing is greater

than 70oC an alarm shall be initiated through RTD to the operator. The operator shall check the circulation pump operation & the coolant flow at local to bring down the sump oil temperature. In case if the temperature of sump oil is unable to be brought down, APH electric motor/air motor shall be tripped manually.

When APH’s electric motor trips simultaneous impulse will be give for :-

3)To start Air motor with 5 secs delay

*same similar interlocks for starting APH – B(APH – A is OFF)


63

BOILER AUXILIARIES INTERLOCK & PROTECTIONAPH’s INTERLOCKS & PROTECTION

Tripping of APH-A (APH-B is ON) or vise versa:1) Gas I/L & O/T damper, Secondary air O/T damper, and PA I/L & O/T damper

of the tripped AH shall be automatically closed.2) Boiler load reduced approx 60 %MCR

Tripping of both APH A & B3) Operator may try for restarting the APHs. 4) If any one of the APH is not started within 5 minutes the operator shall

manually trip the boiler.5) All Gas I/L & O/T damper, Secondary air O/T damper, and PA I/L & O/T

damper should be opened


64


Interlocks for Oil Circulation Pumps of support bearings(SB) of Air heaters:2 x 100% oil circulation pump have been provided for the support bearing. Anyone of the two oil circulation pumps can be pre selected as main pump and the other as standby.

Following interlocks shall be provided for Oil Circulating Pumps

APH ON

SB LOP1 OFF>2SECAND

APH ON

SB LOP1 ON

LOW FLOW>30SECS

AND

START CMD TO OTHER LOP

OR


65


Interlocks for Oil Circulation Pumps of guide bearings(GB) of Air heaters:2 x 100% oil circulation pump have been provided for the guide bearing. Anyone of the two oil circulation pumps can be pre selected as main pump and the other as standby.

Following interlocks shall be provided for Oil Circulating Pumps

APH ON

GB LOP OFF>2SECAND

APH ON

GB LOP1 ON

LOW FLOW>30SECS

AND

OR START CMD TO OTHER LOP


66

PULVERISER INTERLOCKS & PROTECTION

Conditions existing when the unit is shutdown and prior to starting of MILL:

1)Mill Motor off

2)LOPs for Mills off



67

Starting of Mill:

A)MILL shall be prohibited from starting till the following conditions are satisfied:1) Bunker Outlet Gate open2) Feeder Inlet Gate open3) Mill Discharge valves open(4nos)

4) Seal air valve is open5) Mill start permit from Pulveriser Lub Oil System6) Mill outlet temp not high <94˚C7) Cold air Gate open8) Tramp Iron Hopper Valve open9) Mill/Oil elevation start permit.

10) Nozzle tilts placed in the horizontal position(for 1st pulveriser only).11) Primary air pressure is adequate(>650mmwc)12) Pulveriser Bowl DP Adequate >200 mmwc13) MILL status off & ignition permit available

PULVERISER INTERLOCKS & PROTECTIONBOILER AUXILIARIES INTERLOCK & PROTECTION


68

Starting of Mill:

B) When MILL is started, impulses shall be given for :-

1)Permission to open the hot air gate(HAG) & impulse to regulate HAG

2)Permission to start the Raw Coal Feeder.

*Same similar interlocks for Starting all other Mills



69

Tripping of Mill:A) Mill will trip automatically under following conditions:-

Motor winding temperature too high>130oC >5sec

Motor bearing temperature too high>85oC >5sec

Mill vibration too high>9mm/s> 15 sec

Mill trip from Pulveriser Lub Oil System(PLOS)

Mill bearing temperature too high> 90oC>5sec

OR LOGIC

Trip

signal to Mill

motor

MFT acted

Mill discharge damper not open

Both PA fans trips

Ignition energy disappears before 180 secs from feeder start



Seal air header pressure very low>60secs

70

Tripping of MILL:

B) When MILL is tripped, simultaneous impulses shall be given for :-

1)Signal to trip the feeder’s motor

2)To close the hot air gate.

3)To bring cold air damper to minimum position

*Same similar interlocks for other Mill tripping.



71

RAW COAL(RC) FEEDER INTERLOCKS & PROTECTION

RC Feeder Starting:

A) RC Feeder motor is prohibited from starting till the following conditions are

satisfied:

1)No boiler trip condition prevails.

2)Elevation AC&DC available

3)Ignitor energy is available

4)Pulveriser is ON

5)Hot air gate is open



72

RC FEEDER INTERLOCKS & PROTECTION

RC Feeder Starting:

B) RC Feeder motor is simultaneous impulse shall be give for :

1)To include feeder output in totalizing circuit after 15secs

2)To release feeder speed control to auto after 50secs

3)To modulate fuel air dampers according to feeder speed after 50secs



73

RC FEEDER INTERLOCKS & PROTECTIONTripping of RC feeder motor:

RC feeder motor will trip automatically under following conditions:-

Boiler Trips

Elevation DC fails >2secs

Pulveriser trips

RC motor’s electrical trip

Elevation AC failsOR

LOGIC

Trip

signal to RC motor

Loss of coal flow & pulveriser amps low

Ignition energy disappears before 180 secs from feeder start



74

BOILER AUXILIARIES INTERLOCK & PROTECTIONREHEATER PROTECTION

This protection is provided to protect the Reheater against starvation of steam flow during abnormal conditions. To take care of Reheater protection, the Boiler shall be tripped after 10 seconds, when any of the following conditions occur.

Reheater protection will armed automatically under following conditions:

DRUM PRESSURE >8ata

ANY FEEDER ON

BOILER FIRING SIGNAL FROM FSSS

OR

LOGIC

AND

LOGIC

REHEATER PROTECTION ARMED


75

BOILER AUXILIARIES INTERLOCK & PROTECTIONREHEATER PROTECTION

Reheater protection will automatically enable under following conditions:

REHEATER PROTECTION ACTED(Boiler Trip)

HPBP OR LPBP OPENED<2%

AND

LOGIC

GENERATOR CKT BREAKER OPENED

REHEATER PROT ARMENDOR

LOGIC

10SEC >

AND

LOGIC

IF ANY OF 1 OR MORE VALVES CLOSED1. HPSV1 5. IPSV12. HPCV1 6. IPCV13. HPSV2 7. IPSV24. HPCV2 8. IPCV2

HPBP OR LPBP OPENED<2%

REHEATER PROT ARMEND



T H A N K S

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