PRESENTED BY

MAHAVIR RATHORE

INTRODUCTIONBOILER DRUM IS DEVICE WHICH

SEPARATE THE WATER FROM THE STEAM & WATER MIXTURE GENERATED IN FURNACE WALL AND REDUCE THE DISSOLVED SOLID CONTENTS OF THE STEAM TO BELOW THE PRESCRIBED LIMIT OF 1 PPM.

MODIFIED RENKINE CYCLE

1

2

3 4

T

5

S

1-2 WORK DONE BY BFP

2-3 HEAT ADDITION IN ECONOMISER

3-4 HEAT ADDITION IN FURNACE WW

4-5 HEAT ADDITION IN SUPERHEATER

5-5’ WORK DONE BY HP TURBINE

5’-6 HEAT ADDITION IN REHEATER

6-7 WORK DONE BY IP&LP TURBINE

7-1 HEAT REJECTION IN CONDENSER 7

6

5’

T1

T5

M.S. LINE

FROM F.R.S

300 MWF

RO

M C

RH

LIN

E

HRH LINE

CR

H L

INE

ERECTION OF DRUM• The drum is placed at the upper part of boiler 164 tons of

whole weight.The weight of drum’s hanger is13 tons.• Sort, count and number the equipments after opening the

package.• Remove the drum’s inside devices that will be installed

after chemical cleaning and store them in storehouse.• Review the vertical and horizontal center line. Line the

horizontal center line as per a quarter of the perimeter of drum while take the center of the connecting surface between down comer and base as norm. The horizontal center line shall be compared with the mark of the center line of equipments and signed with punch. Line out the center line of drum’s hanger according to drawing and take it as the norm of hanger’s erection.

• Check the drum, inside device and alloy parts of hanger by spectrum before erection.

• Temporarily hang the hanger on the drum by chain block before lifting drum.

• Aligning norm of drum: setting dimension will take the boiler’s center line as norm; take 1m elevation of the steel structure as the norm for the elevation; measure the horizontality and elevation by horizontal tubes and do record.

• Alignment method: take the center line of column E-G3 and E-G5 as norm to ensure the longitudinal and latitudinal deviation of drum; take the elevation that is marked on the column E-G3 or E-G6 as norm(as per the accuracy of the 1 meter elevation to choose the column) to ensure the elevation and horizontality deviation of the drum.

• The hydraulic lifting device can be removed after the alignment and reinforcement of drum being finished. The alignment of drum shall be assisted by the hydraulic lifting device.

• The drum shall be reinforced on boiler structure by relative big sized steel after the alignment of drum. The reinforcing measures shall be removed after the erection of pressure parts and before boiler water pressure test.

• The quality control of drum’s erection:• The deviation of elevation shall be not more than

±5mm(for the final one when all the connecting pipes’ installation is completed) ;

• The deviation of horizontality shall be not more than ±2mm;

• The distance deviation between drum’s center line and boiler’s center line shall be not more than ±5mm.

WHY WE REQUIRE BOILER DRUM

Function of drum

1.To store water and steam sufficiently to meet varying load requirement

2. To aid in circulation3. To separate vapor and steam from water steam

mixture, discharge by riser.4. To provide enough surface area for liquid steam

disengagement.5. To maintain certain desired PPM in the drum

water by tri sodium phosphate inject and blow down.

CONTINUE………..

THE DRUM IS EQUIPED WITH-

TWO DUAL COLOR WATER LEVEL GAUGES ONE ELECTRICAL WATER LEVEL GAUGE FOR PURCH

WATER FILLED FOUR SINGLE ROOM BALANCE VESSLES PRESSURE MEASURING POINT METAL TEMP. MEASURING POINT SAFETY VALVES VENT LINE NITROGEN FILLING LINE CHEMICAL FEEDING LINE MAIN HOLE

DRUM AND INTERNALS

DRUM INTERNAL Drum internals is single sect vaporize system, the first stage Drum internals is single sect vaporize system, the first stage

distributor is turbo separator (vertical) of Φ315,. The second distributor is turbo separator (vertical) of Φ315,. The second stage distributor is corrugate plates, total 104, they are arranged stage distributor is corrugate plates, total 104, they are arranged at two lines along C.L of drum shell, which is symmetrical; at two lines along C.L of drum shell, which is symmetrical; corrugate plates are located at lean 5, little separated water flow corrugate plates are located at lean 5, little separated water flow into water space through drain tube located on bottom of drum, into water space through drain tube located on bottom of drum, on top of drum are equipped with equalizing hole plates. On on top of drum are equipped with equalizing hole plates. On bottom of drum a baffle is equipped to avoid directly contact bottom of drum a baffle is equipped to avoid directly contact between saturated water and feed water. In order to avoid water between saturated water and feed water. In order to avoid water over cooling and stagnating, the design values of production rate over cooling and stagnating, the design values of production rate of steam between front part and rear part is 0.35 to 0.65, which to of steam between front part and rear part is 0.35 to 0.65, which to produce the pressure to in force mixture to flow from front to produce the pressure to in force mixture to flow from front to behind, so the temperature of up and down of drum can be the behind, so the temperature of up and down of drum can be the same.same.

The normal water level of drum is 100mm below the drum The normal water level of drum is 100mm below the drum centerline, the allowable fluctuate is ±50mm.centerline, the allowable fluctuate is ±50mm.

1. Cyclone separator 2. Drain pipe 3. Perforated plates 4. Corrugated plate 5. Feeding pipe 6. Blow down tube 7. Emergency drain tube 8. Baffle plate 9. Mixture of vapor and water 10. Saturation steam11. Feed water12. Return water 13. Chemical dosing tube

DRUM INTERNALS

DRUM SPECIFICATION1. CONSTRUCTION - SINGLE

2. MATERIAL SPECIFICATION - DIN 13MnNiMo54

3. MANUFACTURER OF PLATE MATERIAL - GERMANY

4. ULTIMATE TENSILE STRENGTH OF PLATE - 575 MPA

5. DESIGN PRESSUER - 19.66MPA

6. DESIGN METAL TEMP. - 363 C

7. DESIGN STRESS AT WORKING METAL TEMP. - 205 Kg/CM2

8. DESIGN STANDARD - DIN

9. DESIGN THICHNESS FOR STRAIGHT PORTION - 97 MM

10. DESIGN THICHNESS FOR DISHED END - 127.8 MM

11. ACTUAL THICKNESS USED FOR STRAIGHT PORTION - 145 MM

12. ACTUAL THICKNESS USED FOR DISHED END - 145

13.OVERALL LENGTH OF DRUM - 22250 MM

14. INSIDE DIA. OF DRUM - 1800 MM

15. CORROSION ALLOWANCE - 4 MM

16. ELEVATION OF DRUM CENTER LINE FROM GROUND - 66800 MM

17. NO. OF CYCLONIC SEPARATOR - 108

19. NO. OF RISER STUB - 94

20. NO. OF DOWN COMER - 04

21. NO. OF SECONDARY DRIER - 2 ROWS

22. NO. OF FINAL DRIER - 2 ROWS

MAXIMUM PERMISSIBLE TEMP. DEFFRENCE BETWEEN ANY TWO PART OF THE DRUM

a. DURING NORMAL - 40 C

b. DURING ACCELERATED STARTING - 50 C

c. DURING SLIDING PRESS. OPERATION FROM 100% - 40 C

TMCR TO 40% TMCR

WATER CAPACITY AT MCR CONDITION B/W NORMAL - 23 M3

AND LOWET WATER LEVEL PERMITED

WATER VOLUME - 54 M3

CONTINUE…….

WORKING PROCEDURE OF DRUMSTEP–1 WATER ENTERS INTO THE DRUM THROUGH ECO FEED LINES FORMING A COMMON HEADER AND FALL DOWN THROUGH HOLES OF HDR AND COLLECTED ON THE LOWER SURFACE OF DRUM.

STEP–2 WATER FALL DOWN THROUGH DOWN COMER AND ENTER INTO WATER WALL LOWER HEADERS.

STEP–3 WATER GOES UP THROUGH WATER WALL AND THE MIXTURE OF WATER AND STAEM ENTERS INTO THE WATER WALL UPPER HEADER.

STEP-4 STEAM AND WATER MIXTURE FROM UPPER RING HEADER OF WATER WALL ENTER INTO THE DRUM THROUGH RISER TUBES.

STEP-5 MIXTURE ENTER INTO THE DEFLECTING SEPARETOR AND ROTATE DUE TO CENTRIFUGAL FORCE.

CONTINUE…..

STEP 6 - DUE TO THE WEIGHT WATER PARTICAL FALLS DOWN ON THE SALVER AND MIX WITH THE FEED WATER AND STEAM DUE TO THE LIGHT DENSITY GOES UP.

STEP-7 STEAM ENTERS INTO THE SECONDRY OR CORRUGATED SEPARATOR AND PASS THROUGH CORRUGATED FINS. WATER PARTICAL FALLS DOWN AND MIX WITH FEED WATER.

STEP– 8 NOW STEAM ENTERS INTO THE FINAL CORRUGATED SEPARATOR WHERE THE REST WATER PARTICAL FALLS DOWN AND MIX WITH FEED WATER FLOWING THROUGH CONNECTING PIPE AND STEAM FINALY GOES UP INTO THE SATURATED STAEM LEAD LINE PASSING THROUGH PEFORATED PLATES.

CHEMICAL DOSING IN DRUM

IT IS USED TO REMOVE THE SILICA PARTICAL FROM THE WATER COMING FROM THE ECO FEED LINE TO AVOID CORROSION ON THE TURBINE BLADES. WE USE TRI SODIUM PHOSPHATE WHICH REACT WITH WATER AND SEPARATE THE SILICA PARTICAL WHICH COMES DOWN THROUGH CONTINUOUS BLOW DOWN LINE

NITROGEN FILLING IN DRUM

FIRST DRUM INTERNALS ARE CEANED BY THE CHEMICAL TO REMOVE THE FOREIGN PARTICALS AND OTHER INGRADIENTS WHICH ARE PRESENT OR STICKED DURING MANUFACTURING THEN

NITROGEN IS FILLED INSIDE THE DRUM TO AVOID THE REACTION OF THE INTERNALS WITH THE OTHER FOREIGN MATERIALS AND ELEMENTS AFTER CHEMICAL CLEANING

PRIMING AND FOAMING

PRIMING –

IF THERE IS TOO MUCH MOISTURE CARRY OVER BECAUSE OF HIGH WATER LEVEL OR A HIGH STEAMING RATE.

FOAMING – IT IS CONDITION RESULTING FROM THE FORMATION

OF BUBBLES ON THE WATER SURFACE.

Boiler performance data (design coal)

Description Unit B-MCR T-MCR

SH flow t/h 1025 913.2

SH out pressure(gauge) MPa 17.5 17.3

SH outlet temp. Deg.C 540 540

RH flow t/h 841.9 755.3

RH inlet/outlet pres.(gauge) MPa 3.83/3.64 3.43/3.27

RH inlet/outlet temp. Deg.C 329.6/540 318/540

Feed water temp Deg.C 280 272

Drum pres.(gauge) MPa 18.7 18.28

SH 1st spray water flow t/h 6.23 19.08

SH 2rd spray water flow t/h 1.56 4.77

RH spray water flow t/h 6.36 2.91

Furnace outlet gas temp. Deg.C 972 942

Final RH outlet gas temp. Deg.C 781 766

Final SH outlet gas temp. Deg.C 685 674

Primary SH outlet gas temp. Deg.C 426 423

Econ. Outlet gas temp. Deg.C 372 366

Exit gas temp.(modified) Deg.C 127 127

AH inlet air temp. Deg.C 25 25

AH outlet air temp. (PA/SA) Deg.C 225/343 251/341

Coal consumption t/h 173.74 155.88

Boiler design efficiency % 92.66 92.65

Overmuch air coefficient of outlet of eco.

/ 1.22 1.22

CONTINUE………..

==

The SET Pressure and Capacity of Safety Valves and PCVS

Service Description QtySet pressure(Mpa.g)

Blow down(%)

Capacity(Kg/H)

SH outlet

1730WD 1 18.30 4 114000

SH outlet

1730WD 1 18.34 4 115000

Drum 1749WB 1 19.64 4 273000

Drum 1749WB 1 20.03 4 281000

Drum 1749WB 1 20.23 4 286000

PCV outlet

3537W 1 18.12 2 119000

Content Water value Operation measure  

Normal water level (under the centre line of the drum)

100mm

 

Warning value of the high water level 1

+100mm Check the water gauge, reduce the feedwater  

Warning value of the high water level 2

+150mm Open the emergency control valve promptly until the water level is normal  

Tripping value of high water level (The emergency shutdown )

+250mm Emergency shutdown, an automatic control device delays time for 2 seconds  

Warning value of the low water Level 1

-100mm Increase the feed water, check the water gauge , stop blowdown  

Warning value of the ow water level 2

-150mm Check the feedwater system, economize and water wall if they runed normally  

Tripping value of low water level (The emergency shutdown )

-250mm Emergency shutdown, an automatic control device delays time for 2 seconds  

  Note: Warning value, tripping value are as to normal water level.

Water Level Alarm and Protection of the Drum

Trimming Signal

Steam

Steam Flow Sensor

Feed Water Flow sensor

Drum Levelsensor

Control Valve Steam Drum

Feed Water

Normal Water Level

Co

ntr

oll

er

THREE ELEMENT CONTROL SYSTEM

Three-Element Drum Level ControlTo address the issues of phasing still present in the two-element control strategy, a third element, feed water flow is added to the drum level control strategy. In this system the math summer output of the two-element controller is cascaded down to a second

Feed water Flow Controller to act as a Remote Set point.The feed water controller is a fast acting flow controller, which uses feed water flow as its process variable and steam flow as its set point. Thus for every pound of steam flow leaving the boiler a pound of feed water is added. This loop has final control on the feed water valve. As the remote set point from the two element level control changes with steam flow and drum level variations due to blow down or other minor losses, the feed water controller modulates its output to regulate the necessary feed water flow to keep the drum level in a mass/heat balanced and level state.Independent tuning of each controller allows for very precise control of the drum level regardless of steam demand and feed water influences. However it is very important to take the thermal dynamics of the boiler’s recovery rate into account when tuning the feed water controller. If you fail to do this and set the controller reset too fast on the feed water controller you may inadvertently sub-cool the drum and start a cyclic phasing action much like that found in a two-element system. Do the math it will save you a lot of heartache.

The three-element control strategy can easily handle large and rapid load changes because it is matching the mass balance between the steam flow from the boiler and the feed water flow to it. This strategy is a must on multiple boilers sharing the same feed water header and supply system, due to the variations in the available feed water flow to any one boiler, while two or more boilers are on line. This is irrespective to boiler size. Additionally if the boilers are subjected to sudden or unpredictable demand changes such as in a batching process, this strategy is capable of matching these demands without operator trim corrections or supervision.