Manual Part - II-MPL Project 23 07 2012.pdf

Document No.: 2003-E-065-00 Date: 23.07.2012

Project : 2 x 90 TPH CFBC Boiler Customer: MEGHALAYA POWER LTD. W.O. No.: 2M0015 & 16 Issue Status: Controlled Copy – Unauthorized copying not

Page 73 of 177

TITLE: COMMISSIONING & OPERATION

D0 - 0 - 0 - 0 COMMISSIONING & OPERATION



Page 74 of 177

TITLE: FILLING STEAM GENERATOR

D1 - 0 - 0 - 0 FILLING STEAM GENERATOR



Page 75 of 177

TITLE: FILLING STEAM GENERATOR D1.1.0.0 QUANTITY OF FEED WATER

The steam generator must only be filled with degassed and de-mineralized boiler water

(feed water specification are furnished to clients elsewhere). Approximately 36 m3 of

feed water is required to fill the boiler, up to centre of steam drum.

The status of various valves of the steam generator prior to filling water should generally

be:

D1.2.0.0 FIRST TIME OR WHEN THE BOILER IS EMPTY

Sl. No.

Valve Name Condition

1. Vent valves on drum, eco, and super-heaters Open

2.

Drain valves of Superheaters, Evaporator, Economizer,

Furnace walls bottom headers, screen (i.e. evaporator drain

station)

Open

3. Valves on feed control station Close

4. All isolation and control valves of drum mountings except

isolation and control valves of one gauge glass Close

5. All valves on steam circuit Close

Furnace portion is filled usually by filling pump connections through furnace wall drain

header / Evaporator drain station. Start fill pump, open isolation and control valves on

filling pipe up to drain station and allow water to flow at the rate not exceeding approx.

20 TPH.

Close the vent valves on Economiser-I and Economiser-II soon after water flows full

throat from them. Close Economiser and evaporator drain valves.

After drum is filled and the water rises up to saturated steam header water will start

entering the super-heaters. As water starts flowing full from superheated vents close

them one by one. Thus superheated is now full of water. (This will only be required if

Boiler Hydraulic test is to be conducted).



Page 76 of 177

TITLE: FILLING STEAM GENERATOR

In case, fill pumps are not available then water will have to be taken through boiler feed

pumps. Under this condition, all valves under Sl.No. (2) Stated above, have to be

necessarily "closed" before starting feed pumps. Feeding rate should be less than 20

TPH and the water should be taken in boiler through low feed line.

As the drum level reaches approximately (-) 100 mm, switch off filling pump / feed

pump. Close corresponding isolation / control valves.

D1.3.0.0 WHEN THE BOILER IS PARTIALLY FILLED (NORMAL OPERATION)

a) All drain valves are expected to be closed. Maintain same status.

b) Keep vent valves on Economiser, drum and Superheater open.

c) Valves at feed control station and spray control station are closed.

d) All valves on drum steam circuit are kept closed.

e) Valves on drum mountings are kept open except "drain" valves.

Start the feed pump and start topping up by keeping low feed line control valve crack

open (flow <20 TPH). Close vent valves on Economizer-I & II soon after water flows full

throat through them. As the water level in gauge glasses is approx. (-) 100 mmWC

close the low feed control valve and switch off the feed pump.



Page 77 of 177

TITLE: START-UP CHECK LIST

D2 - 0 - 0 - 0 START-UP CHECK LIST



Page 78 of 177


D2.0.0.0 START UP CHECK LIST

Preparatory to light up of the boiler, check the following:

1. All access doors on furnace, flue, ducts, fans etc. are closed properly.

2. Water level in steam drum is around -100mm from NWL.

3. All interlocks are checked & operating satisfactorily. Do not bypass any safety

interlock.

4. All instruments and control systems are operational.

5. All auxiliary dampers are in "start up" position.

6. Sufficient start-up fuel is available.

7. Sufficient main fuel is available.

8. Sufficient feed water is available.

9. The bed level is normal and it is free from any foreign material.

10. Cooling water is switched on.

11. Compressed air is available.

12. Electric power for auxiliary equipment and control is available.

13. All fire protection system is operational.

14. Hydrostatic plugs or test gags are removed from safety valves.

15. Variable/constant load hanger supports are unlocked.

16. Slide gate on bed ash and cyclone ash drop pipes are in closed position and

operational.

17. Bottom ash, cyclone ash and fly ash handling system are fully operational.

18. Pressure gauges especially drum; temperature and level indicators are in

service.

19. Valves required in "close" position:

a) Economiser drains and vent

b) Evaporator drains and vent

c) Drum drain (IBD)

d) All water walls bottom header drains

e) Continuous blow down valves

f) Chemical dosing valve.

g) Screen inlet header drain



9 of 177


20. Valves required in open position:

a) Drum vent

b) Superheater drains and vents

c) Low feed isolation and feed check valves.

d) Drum & Superheater pressure gauge isolation and control valves.

e) Direct gauge glass isolation and control valves.



0 of 177

TITLE: SEQUENTIAL START-UP/SHUTDOWN & BOILER SAFETY INTERLOCKS

D3 - 0 - 0 - 0 SEQUENTIAL START-UP/SHUTDOWN &

BOILER SAFETY INTERLOCKS



Page 81 of 177


D3.1.0.0 SEQUENTIAL START-UP

Boiler auxiliaries have to be started in the following order so that safe light up is

achieved without any conflict with interlocks. Boiler is to be purged before light up from

the cold condition (cold start-up). For this purpose, a soft Timer shall be built in the

DCS, the setting of which can be adjusted. During the cold start-up, the setting of this

timer is to be set for 10 min., which is the purge cycle duration. Setting time of 10 min.

ensures about 3 volumetric changes of air in the Boiler and the air / flue gas path. This

setting has been followed in Cold Cyclone CFBC Boiler installations in Germany, which

yielded satisfactory results. This also meets NFPA requirement.

Under all condition of boiler starting it must be ensured that water level in steam drum is

approx. (-) 100 mm from NWL and coal feeders are not in operation. Also coal isolation

gates above siphon are in closed position.

D3.2.0.0 START-UP SEQUENCE

D3.2.1.0 AIR /FLUE GAS START-UP SEQUENCE

The damper positions marked ‘*’ thus below are only for starting-up of fans. The suction

and discharge dampers of ID, SA and PA fans are to be kept closed during the starting

of respective fans to isolate the system resistance. Once ID fan is started, followed by

SA fan, PA fan in a sequence, the discharge dampers of ID, SA and PA fans are fully

opened. The control dampers of SA and Tertiary Air local to the boiler are also to be

kept around 50% open. SA Fan speed is kept low i.e. about 10% of rated speed and

maintained during the light-up. Thereafter, speed of PA fan is gradually increased till the

minimum PA flow condition required for light-up is reached. The ID fan speed is slowly

increased with the VFD Control, commensurate with PA fans’ speed, basically to

maintain around (-) 30 to (-) 50 mm (may be around – 10 mm during oil firing) Furnace

draft.



Page 82 of 177

TITLE: SEQUENTIAL START-UP/SHUT-DOWN & BOILER SAFETY INTERLOCKS

D3.2.1.1 ID FAN START / STOP LOGIC

STARTING LOGIC

ID FAN 1/2 will start after ID Fan start command is given from DCS only when the

following conditions are satisfied:

1. Drive selected (1-IDF1/IDF2-YRE) Remote

2. Motor (1- IDF1/IDF2-XH) Not Tripped

3. Control (1-IDF1/IDF2-YRE) Available

4. Local Stop Push Button Not Operated

5. ID Fan disc damper (1-FLG-ZSC-02/05) Closed

6. ID Fan (1-IDF1/IDF2-YBO) Not running

7. ID Fan Suc. damper (1-FLG-ZSC-00/03) Closed

8. ID Fan – bearing (DE) temp. Not high

9. ID Fan – bearing (NDE) temp. Not high

AND

11. ID Fan 2/1 (1-ID-FAN2/IDFAN1-YBO) Running

OR

12. ID Fan 2 Discharge Damper (1-FLG-ZSC-05/02) Closed

Note: Start ID Fan 1 and maintain Furnace Draft around (-) 30

mmWC.



Page 83 of 177


STOP / TRIPPING LOGIC FOR ID FAN

If any one of the following signals is present ID Fan 1/2 will stop / trip

1. ID Fan stop command From DCS

2. Control (1-IDF1/IDF2-YRE) Not Available

3. Motor (1-IDF1/IDF2-XH) Tripped

4. ID Fan A Bearing (DE) temp High

5. ID Fan A Bearing (NDE) temp High

6. Furnace Pressure Very Low

7. ID Fan Bearing (DE) Vibration Very High

8. ID Fan Bearing (NDE) Vibration Very High.

9. Local Stop Push Button Operated

.

.



Page 84 of 177


SA FAN – 1/2 – START / STOP LOGIC SA Fan will start after SA Fan start command is received from the CRT only when the


1. Remote (1- SAF1/SAF2-XS) Selected

2. Control/MCC (1-SAF1/SAF2-XH) Available

3. MCC (1- SAF1/SAF2-XF) No Fault

4. Local Stop (1-SAF1/SAF2-XNOT) Not Operated

5. SA Fan 1/2 Discharge Damper (1-SAP-ZSC-01/03) Closed 6. SA Fan 1/2 (1- SAF1/SAF2-XA) Not Running 7. SA Fan 1/2 bearing (DE) temp Not high

8. SA Fan 1/2 bearing (NDE) temp Not high

AND

9. Any ID fan Running

10. SA Fan – 2/1 Discharge Damper (1-SAP-ZSC-03/01) Closed

11. Furnace pressure < max

12. Furnace Pressure >min

OR 13. SA Fan – 2/1 Running

SA Fan – will stop /trip if any one of the following signals is present:

1. Control/MCC (1-SAF1/SAF2-XH) Not Available

2. MCC (1- SAF1/SAF2-XF) Fault

3. SA Fan – 1/2 bearing (DE) temp HI – HI

4. SA Fan – 1/2 bearing (NDE) temp HI – HI

5. ID fan 1 & 2 Not Running

6. SA Fan stop command From CRT

7. Stop command From SEQ tripping

8. Fan Bearing (DE/NDE) Vibration Very High

9. Furnace Pressure Very High

10. Furnace Pressure Very Low

11. Drum Level Very High

12. Local Stop (1-SAF1/SAF2-XNOT) Operated



Page 85 of 177


PA FAN - 1/2 – START / STOP LOGIC PA Fan – will start after receiving PA Fan – start command from CRT only if the


1. Drive selected (1-PAF1/PAF2-YRE) Remote

2. Control (1-PAF1/PAF2-XH) Available

3. Breaker (1-PAF1/PAF2-YBR) Ready

4. PA Fan 1/2 Discharge damper (1-PAP-ZSC-01/03) Closed

5. PA Fan1/2 Vane(1-PAP-ZSC-00/02) Minimum

6. PA Fan – 2/1 (1-PAF1/PAF2-YBO) Not Running.

7. PA Fan bearing (DE) temp Not high

8. PA Fan bearing (NDE) temp Not high

9. Furnace Pressure > Minimum

10. Furnace Pressure < Maximum

11. Drum Level < Maximum

12. Drum Level > Minimum

13. Any ID fan Running

14. Any SA fan Running

15. TA flow > Min

16. SA flow > Min

17. PA Fan – 2/1 Discharge Damper (1-PAP-ZSC-03/01) Closed

OR 18. PA Fan – 2/1 (1- PAF1/PAF2-YBO) Running.

20 PA Fan – 1/2 Stop Command from CRT Not Present



Page 86 of 177


PA Fan 1/2 – will stop / trip if any one of the following signals is present:

1. PA Fan stop command From DCS

2. Breaker (1-PAF1/PAF2-YBR ) Not Ready

3. Motor bearing (DE) temp HI - HI

4. Motor bearing (NDE) temp HI - HI

5. Fan bearing (DE) temp HI - HI

6. Fan bearing (NDE) temp HI – HI

7. PA Fan stop command From seq. tripping

8. Control (1- PAF1/PAF2-XH) Not Healthy.

9. Both SA Fans Tripped

10. Both ID Fans Tripped

11. Fan Bearing (DE/NDE) Vibration Very high

12. Boiler Tripped

13. SA Flow < Minimum

14. TA Flow < Minimum

15. PA Discharge Pressure > Maximum



Page 87 of 177


B. BOILER AIR PROTECTION: (PRECONDITIONS):

Fluidised bed temperature < max. 3

Furnace draft > min. 2

Furnace draft < max. 2

Siphon I exit temperature < max. 2

Siphon II exit temperature < max. 2

Drum level > min. 2

Drum level < max. 2

Primary air flow > min. 2

Bed temperature > Min 1A

Note: Out of four bed temperature measuring points, normally average of

four is considered. In case there are three in operation only, average

of three may be considered. Under the worst conditions, average of

two may be considered on "short term" basis.

BOILER MUST BE TRIPPED IF ONLY ONE BED TEMPERATURE

MEASUREMENT IS AVAILABLE



Page 88 of 177


BOILER OIL PROTECTION / PRECONDTIONS TO START HOT GAS GENERATOR.

Before any fuel firing can take place a satisfactory Purge cycle must be completed. To

start a furnace Purge cycle the following conditions must be satisfied:

1. Primary air pressure Not low

2. Any PA Fan Running

3. Atomising air pressure (1-SEA-PSL-01) Not low

4. Fuel oil pressure (1-LDO-PSL-01) Not low

5. Fuel oil pressure (1-LDO-PSH-01) Not high

6. Flame Not On

7. Oil SSOV (1-LD0-CTS-01) In closed position

8. HAG outlet gas temp Not HI - HI

9. HAG bypass isolation damper (1-PAP-ZSC-06) Fully closed

10. Scavenging on No

11. Instrument Air Pressure (1-INS-PSL-01) Not Low

12. Diff. Pressure across HGG –1 (1-FLG-DPT-01) Not Low

13. PA Flow > Min

14. Burner Start Command Not Present

15. Refractory Temperature Not High

With all above conditions satisfied furnace purge ready lamp will be on. After

Purge start PB operated Furnace Purging will start and Furnace Purge ready lamp

will be off. Purge progress indication will be available in CRT and after a time delay

of 5 mins. Purge Complete indication will be available on CRT and Burner Ready

will be available when Purge is complete AND Oil Valve opening is > 25% and <

50% AND Oil Gun IN Position



Page 89 of 177


Start Oil Burner From Local/DCS

Burner Start Command:

With Burner Ready signal On AND Local / Remote mode selected

AND

Burner Start PB Operated OR Burner Start command from CRT

Following Cycle will be initiated:

Step – 1 Ignitor Will Be Inserted And When Ignitor Retract Limit Switch Is Released Ignitor

transformer Will Be energized For 20 secs.

Step – 2

When Ignitor is Inserted, Atomising Air Valve will Open and Oil Valve will Open

simultaneously. Step – 3 – Condition – 1

Ignition Timer Over and Oil Flame established. Oil and Atomising

Valves will remain Open

Condition – 2 Ignition Time Over, Oil valve Opened But Oil Flame Failed to establish.

Oil valve will close. Ignitor will be Inserted and energized. Scavenge On/ Start

Indication will be available on CRT and Atomising Valve will remain in open

condition. Scavenge Valve will Open.

After 20 secs. HEA will be De-energised and after 25 secs. both scavenge and

atomizing valve will close.

Step – 4

Oil Burner firing and burner stop PB Operated

Oil Valve will Close and Atomising Valve will remain Open.

Scavenging On/Start indication will be available on CRT.

Ignitor will be Inserted and energized

Scavenging Valve will Open.

After 20 secs. Ignitor will be De-energised and retracted.

After 25 secs. Both Scavenging and atomising Valves will close.



Page 90 of 177


Step – 5 Oil Burner Firing and HAG Trips due to any one of the following conditions:

Primary Air Pressure Low

Atomising Air Pressure Low.

HAG Outlet temperature High High.

Emergency Stop PB Operated.

Oil pressure low or High

Diff. Pressure across HAG Low

Primary air Flow Low

Then the Following Occurs:

Oil Valve will Close and atomising Valve will close.

No Scavenging will take place.



Page 91 of 177


D. PRECONDITIONS TO START MAIN FUEL

FUEL FEEDER START / STOP SIGNAL

Fuel feeder will start after start command is given from CRT if the following conditions are satisfied:

1. Selection (1-VFD02/03-XS) Remote 2. CF – 1 (1-VFD-02/03-XA) Not running 3. Feeder 1/2 Outlet Date (1-FHS-ZSO-02/04) Open 4. Drive (1-VFD-02/03-XH) Healthy 5. Feeder.(1-VFD-02/03-XT) Not Tripped 6. Bed temp > Min 1A (2 out of 4 logic) 7. Air protection O.K. 8. Boiler Not tripped 9. Any PA fan Running 10. Fuel feeder Stop PB (DCS) Not operated 11. Trip coal feeder signal Not present.

Start one Fuel Feeder from DCS Vary Speed as Required. Start second fuel feeder as required.

Note: Adequate numbers of “Rods” are withdrawn from Rod type gate of Feeder I and / or II prior to check permissive.

Fuel feeder will stop / trip if any one of the following signal is present :

1. PA fan Not running 2. Boiler Tripped 3. Bed temp > 920deg C 4. Fuel feeder –1 Drive(1-VFD-02/03-XT) Fault/Trip 5. Fuel feeder –1 stop PB (DCS) Operated 6. Drive (1-VFD-02/03-XH) Not Healthy 7. CF O/L gate (1-FHS-ZSC-02/04) Closed 8. Bed Temperature < Min 3 9. Siphon 1 / 2 Outlet temperature > Max (450 oC)



Page 92 of 177


D3.3.0.0 TRIPPING SEQUENCE -

A. AIR FLUE TRIPPING SEQUENCE:

Coal tripping sequence OK

PA fan Off / Trip

PA fan suction dampers (control) Close

PA fan discharge dampers Close

SA fan Off / Trip

SA fan Suction (control) damper Close

SA fan discharge damper Close

ID fan Off / Trip

ID fan suction (control) damper Close

ID fan discharge damper Close

Note: All discharge dampers of ID; SA, PA fans may also be closed.



Page 93 of 177


BAMBOO CHIP FEEDER START / STOP Bamboo Chip Feeder will start after start command is given from CRT if the following Input conditions are satisfied:

1. Remote (1-VFD07-XS) Selected 2. Drive (1-VFD07-XH) Healthy

3. Belt Conveyor (1-VFD08-XA) Not Running

4. Bed Temperature (2 Out of 3 Logic) > Min 1A

5. Air Protection OK

6. Boiler Not Tripped

7. BCF (1-VFD07-XA) Not Running

8. PA Fan 1 or 2 Running

9. BCF Stop PB (DCS) Not Operated

10. Drive (1-VFD07-XT) No Fault

11. Trip Signal Not Present

12. Local Stop PB Not Operated

Bamboo Chip Feeder will stop / Trip if any one of the following input signals is present:

1. PA Fans 1 and 2 Not Running 2. Boiler Tripped

3. Bed temperature > 920 Deg C

4. BCF Stop PB (DCS) Operated

5. Drive (1-VFD07-XH) Not healthy

6. Drive (1-VFD07-XT) Fault

7. Bed temperature < Min 3

8. Local Stop PB Operated



Page 94 of 177


D3.4.0.0 SAFE LIMITS/TRIP LEVELS FOR CFBC BOILER

Sl. No.

Description Limits

(Max/Min) Set Value Unit

1. Furnace pressure min. 2

max. 2

(-)150

(+)100 mmWC

2. ID fan I inlet pressure

ID fan II inlet pressure min. 2 (-)510 mmWC

3.

Primary air flow (Total)

Primary air flow to the HGG

min. 2

min. 2

11

5.5

kg/sec

kg/sec

4.

Drum level-I

Drum level- II

Drum level-I

Drum level-II

min. 2

min. 2

max. 2

max. 2

(-)320

(-)320

150

150

mm

5.

Fluidised bed temperature


Fluidised bed temperature coal


max. 2

max. 3

min. 1A

min. 3

940

920

> Ignition

Temp

350

°C

Note: 1. "Min .2" and "Max. 2" are limiting values of boiler trip.

2. In the event of “Boiler trip", (on account of reaching min 2/max 2 values) "Air/Flue

tripping sequence" should be initiated automatically. This will immensely help to

achieve quick start of boiler when normal condition is restored for restart.

3. Permissive (min.) to start coal firing is indicated a "Min. 1A".

4. Coal feeders (only) should trip if fluidised bed temperature exceeds "Max.

3" or drops below "Min. 3" once coal is charged.

5. Set values mentioned for Bed Temp. (Sl. No. 5 above) are indicative and

shall be adjusted during commissioning.

6. ID Fans shall run for approx. 10 minutes in case of planned trip.

7. CO Vent valve shall be opened after boiler trip as a safety measure.



Page 95 of 177


D3.5.0.0 LIST OF ANNOUNCIATION / ALARM POINTS: Sr.No. Description Setting Unit Remarks

1. Drum Level (2 out of 3 voting of LT), + 50 mm High

2. Drum Level (2 out of 3 voting of LT) - 100 mm Low

3. Drum Pressure 130 kg/cm² (g) High

4. Final Steam Pressure 114 kg/cm² (g) High

6. Final Steam temp. 540 °C High

8. HGG Outlet/Wind Box Temperature 870 °C High

9. Bed Temperature (Average of 4nos.Thermocouples) 880 °C High

10. Bed Temperature (Average of 4nos.Thermocouples) 600 °C Low

11. Bed Height 1200 mm High

12. Bed Height 800 mm Low

13. Oxygen at Eco I inlet 5 /2.5 % High/ Low

14. Primary air Discharge Pres 1660 mmWC High

15. Sec. air Discharge pressure 600 mmWC Low

16. Furnace pressure - 80 mmWC Low

17. Furnace pressure +50 mmWC High

18. ID Fan 1 /2 Tripped

19. PA Fan 1/ 2 Tripped

20. SA Fan 1/ 2 Tripped

21. Fluidizing Air Bed Cooler temp 1 / 2 oC High

22. Cyclone Ash Screw feeder 1 / 2 Tripped

23. Cyclone Ash Screw feeder 1/2 cooling water flow Low

25. Cyclone Ash static cooler 1 / 2 level High

26. Coal Feeder 1 / 2 Tripped

27. Coal Feeder 1 / 2 No coal flow 28. HGG refractory temp. 870 oC High

29. HGG Flame failures

30. HGG Oil pressure High



Page 96 of 177


Sr. No. Description Setting Unit Remarks 31. HGG Oil pressure Low

32. HGG atm. air pressure Low

33. Instrument Air Pressure Low

34. ESP 1/2/3/4 hopper level High

35. Fuel oil pump 1 / 2 Tripped

36. BFP A / B/ C Suction Pressure Kg/cm2 Low

37. BFP A / B/ C DE / NDE Vibration microns High

38. DP Across BFP A / B/ C Suction Strainer Kg/cm2 High

39. Deaerator Level mmWC Low

40. HSD tank level Very Low

NOTE: 1. Above initial settings may have to be changed in course of

commissioning.

2. Bearing and winding Temperatures of Boiler Auxiliaries are not

listed.



Page 97 of 177


D3.6.0.0 LIST OF SOE POINTS:

Sr. No. Description Setting Unit Remarks

1. Drum Level (2 out of 3 voting of LT) +150 mm. HI – HI

2. Drum Level (2 out of 3 voting of LT) -320 mm LO – LO

3. Bed Temperature (2 out of 4 voting of TC) 940 °C HI - HI

4. Bed Height 1400 mm HI – HI

5. Bed Height 500 mm LO- LO

6. Primary Disch. Pressure 1750 mmWC High

7. Primary Disch. Pressure 800 mmWC LO-LO

8. Furnace Pressure -150 mmWC LO –LO

9. Furnace pressure +100 mmWC HI – HI

10. ID Fan 1 / 2 Tripped

11. PA Fan 1 / 2 Tripped

12. SA Fan 1 / 2 Tripped

13. Primary air flow <15 Kg/sec Low

14. Secondary air flow <2 Kg/sec Low

15. Tertiary air flow <1 Kg/sec Low

16. ID Fan Brg. (DE / NDE) Temp. 90 Deg C HI-HI

17. PA Fan Brg. (DE / NDE) Temp. 90 Deg C HI-HI

18. SA Fan Brg. (DE / NDE) Temp. 90 Deg C HI-HI

19. ID Fan (DE / NDE) Brg. Vibration 11 mm/sec High

20. PA Fan (DE / NDE) Brg. Vibration 11 mm/sec High

21. SA Fan (DE / NDE) Brg. Vibration 11 mm/sec High

22. Final Steam Temperature 480 Deg C LO-LO

23. ID Fan Suction Pressure -550 mmWC LO-LO

NOTE: 1. Above initial settings may have to be changed in course of

commissioning.



Page 98 of 177

TITLE: HOT GAS GENERATOR - OPERATION

D4 - 0 - 0 - 0 HOT GAS GENERATOR - OPERATION



Page 99 of 177


D4.1.0.0 PURPOSE OF HOT GAS GENERATOR (HGG)

In CFBC Boiler, usually coal or lignite is the main fuel for normal operation. It is

therefore necessary that the injected fuel falls in the surrounding which is conducive to

start its burning and is sustained. PF boilers have "Light-up" oil burners, likewise in

CFBC boiler, we have to raise the temperature of bed material, before charging main

fuel to a level which is, say 20°C above the ignition temperature of fuel.

The HGG is mounted on cradle and suspended from Constant Load Hangers. HGG

outlet is fixed to the Airbox for initial heating of the bed material. The HGG is fed by

combustion air, i.e. primary air and dilution air from PA Fans. A set of dampers

regulates the air quantity suitably. Hot gas generators gradually raise the bed

temperature at a predetermined rate up to ignition temperature of the main fuel (coal).

D4.2.0.0 OPERATION OF HGG

Under "cold start" condition, Fans are started in the sequence ID, SA, PA. Furnace

draft is maintained at about (-) 30 mmWC keeping primary airflow just above fluidisation

level. Pre-requisites for starting HGG are:

1. Oil pressure at burner gun 6 Kg/cm2 (g) minimum

2. Compressed air for atomisation 7 Kg/cm2 (g) minimum

3. Differential across the HGG 25 mmWC minimum

4. Total primary air flow 17 Kg/sec minimum

One (1) Local Push Button Stations (LPBS), with various digital indicators, lamps & etc.,

are provided for the operation of the HGG, respectively. The burner management logic

and safety interlocks are built in the main DCS.



Page 100 of 177


Press burner "start" push button. Sequential operation will start, the HEA Ignitor

will insert & spark will start, which will initiate to open oil "shut off valve" and

atomizing air valve.

As the Oil starts flowing, the Main burner is lighted up keeping oil flow around 150 kg/hr.

The sparking of igniter will stop after 15secs. In case the Oil does not catch fire during

this period the whole sequence is to start again.

The combustion air damper is to be adjusted to the predetermined “air-fuel oil ratio” for

efficient combustion and to keep the flame healthy. Keep the dilution air quantity

sufficient to maintain HGG outlet gas temperature at around 350 OC initially. Gradually,

start raising the oil flow till it reaches around 900 kg/hr. Open dilution air damper such

that HGG outlet gas temperature rises gradually and does not exceed 850 OC in any

case. This is important to have uniform thermal expansion of refractory bricks of HGG.

Main fuel (coal) is charged after temperature of bed material exceeds ignition

temperature of the fuel and all other boiler interlocks are fulfilled. Due to cold fuel,

initially there is slight "dip" in bed temperature. However, it picks up soon and after the

bed temperature exceeds 700°C, gradually reduce the oil flow to about 250 kg/hr and

then smoothly trip the HGG.

The entire HGG operation can also be done in “Auto” mode from LPBS, where fuel flow

rate, airflow are regulated at predetermined ratio and also the HGG outlet temp. is

controlled at preset gradient. For further specific operational details of HGG, please

refer HGG supplier’s “Operation & Maintenance Manual”.



Page 101 of 177


D4.3.0.0 HGG – PROTECTION & SAFETY

Control circuit incorporates the operation logic & safety interlocks such as low fuel oil

pressure, low atomising air pressure; differential pressure across the HGG drops below

safe values, HGG gas outlet temperature exceeds safe operating limits, no-flame signal

from flame scanner etc. HGG must be tripped in the event of occurrence of one of the

above conditions. In the event of such tripping, the whole cycle from clearing the

precondition has to be repeated.



Page 102 of 177

TITLE: COLD START-UP OF BOILER

D5 - 0 - 0 - 0 COLD START-UP OF BOILER



Page 103 of 177

TITLE: COLD START-UP OF BOILER

D5.0.0.0 COLD START-UP OF BOILER

During cold start-up of boiler, Hot Gas Generator (HGG) must be fired at minimum firing

rate i.e. about 150 kg/hr fuel oil flow. Also, HGG must be operated with high dilution air

in order to keep the HGG outlet temperatures low. Initially, Superheater drain valves

are kept open, along with drum and Superheater vent valves. When drum pressure

exceeds 2 kg/cm², drum vent valve and Superheater vent valves should be closed.

Once drum pressure reaches approx. 5 kg/cm², Superheater drain valves are kept

partially open for allowing steam flow through the Superheaters.

Adjust fuel oil flow rate, dilution air such that hot gas generator outlet temperature does

not exceed 600º C above the saturated steam temperature. At approximately 15 kg/cm²

drum pressure, close all S/H drains and partially open start up vent valves such that

drum pressure increase is kept within permissible gradient 2 kg/cm² (g) per minute. This

will allow steam flow through the super-heaters and final steam temperature will also

increase as per requirement. Overheating of superheater’s must be avoided.

After fluidised bed temperature reaches about 20 OC above the ignition temperature of

main fuel (coal), charge the main fuel slowly through first stream. Initially, main fuel

feed should be minimum, say 10% of MCR requirement. There may be slight dip in

fluidised bed temperature initially, but in a few minutes the temperature will start

increasing. Gradually reduce oil flow of HGG as fuel firing stabilises. Slowly start the

second stream of main fuel. Once the fuel firing through both the streams is

established, HGG should be switched off gradually. The HGG Bypass damper should

also be opened gradually.

Increase in steam pressure and corresponding increase in steam temperature is

controlled by regulating the start-up vent valve but within permissible gradient i.e. 2

kg/cm2 per minute.

Initially, primary air is admitted through the Airpreheater bypass duct to minimise the

cold end corrosion of Airpreheater. Once the flue gas temperature at Airpreheater outlet

reaches approximately 130º C, Airpreheater is brought in to the service for heating PA &

SA and gradually airflow through Airpreheater by-pass duct is closed.

SEE "PRESSURE RAISING" & CHARGING MAIN FUEL" CHAPTERS ALSO.



Page 104 of 177

TITLE: HOT START-UP OF BOILER

D6 - 0 - 0 - 0 HOT START-UP OF BOILER



Page 105 of 177

TITLE: HOT START-UP OF BOILER

D6.0.0.0 HOT START-UP OF BOILER

Boiler can be started without starting the HGG if the fluidised bed temperature is at least

20ºC above ignition temperature of the main fuel. This is possible after a short duration

shut down of boiler. Main fuel (coal) can be charged directly after all auxiliary fans have

started and bed fluidisation is maintained by ensuring minimum primary air flow.

Starting procedure and preconditions for boiler start-up shall be as explained in the

chapter “SEQUENTIAL START-UP/SHUTDOWN & BOILER SAFETY INTERLOCKS”

(CHAPTER D3-0-0-0).

Start coal feeding with minimum fuel flow (say 10% of MCR requirement) through one

stream. There may be slight dip in temperature of bed initially, but in a few minutes, bed

temperature will start increasing. Start now second stream of coal feed and allow it to

stabilise.

Increase in steam pressure and corresponding increase in steam temperature is

controlled by regulating the start-up vent valve but within permissible gradient i.e. 2

kg/cm2 per minute.

It should be noted that during hot start-up, bed material is likely to get cooled-down

rapidly when minimum primary airflow is established. Therefore, it is advisable to start

charging of fuel quickly while the bed temperature is sufficiently high.



Page 106 of 177

TITLE: PRESSURE RISING OF BOILER

D7 - 0 - 0 - 0 PRESSURE RAISING OF BOILER



Page 107 of 177

TITLE: PRESSURE RISING OF BOILER

D7.0.0.0 PRESSURE RAISING OF BOILER

Boiler circulation should start soon after a fire is lit in combustor. Top headers and drum

should become warmer first followed by lower portion.

Close the steam drum vent when drum pressure is 2 kg/cm²g. Superheater vents may

also be closed. Close Superheater inlet header drains at pressure 5 kg/cm²g and open

the start up vent until the unit is put on load. Opening of start up vent should be

controlled to help raise the pressure in boiler and at the same time the super-heaters

are properly cooled.

It is advisable to warm up the boiler by continuous firing to maintain the continuous

water/steam circulation thus assuring uniform heating of the boiler and minimum of

stresses to the pressure parts and refractory.

In cases where the steam pressure is raised with intermittent firing, it is possible to

arrive at full operating pressure in steam drum and still have lower portion of furnace

relatively cool.

During pressure raising the water level will normally rise to the top of gauge glasses as

steam pressure is increased. This is due to expansion in volume of water due to heat

transfer and circulation. The excess water from system should be removed by blow

down. Especially, lower water wall blow-off may be advantageous, as this will

accelerate circulation.

While giving the blow-down, do not keep the blow-down valves open for more than 20

seconds. The blow-down normally should be given with quick open/close operation.

Pressure and load limits of blow off valves operation are:

Up to 60 kg/cm²g 100% load

60 to 85 kg/cm²g 75% load

85 to 100 kg/cm²g 50% load

100 kg/cm²g and above Never

NEVER DRAIN THE BOILER WHEN THERE IS GLOWING SLAG OR ASH IN THE

COMBUSTOR OR FLUE GAS PASSES.



Page 108 of 177

TITLE: CHARGING MAIN FUEL

D8 - 0 - 0 - 0 CHARGING MAIN FUEL



Page 109 of 177


D8.0.0.0 CHARGING MAIN FUEL

During start-up of boiler, as bed temperature approaches the near to the ignition

temperature of main fuel; preparation to start fuel firing has to be completed to enable

main fuel combustion quickly and reduce expensive oil burning.

The sequences of operations are briefly:

1) Open plate type cut off gates above feeders

2) Open rod type cut off gates above coal feeder

3) Open fuel valves/dampers above siphons

4) Start fuel conveyors (where applicable) at min. speed.

Once minimum bed temperature interlock is cleared, start the fuel feeder at lowest

speed. Initial charge of fuel may cause slight fall in bed temperature but soon bed

temperature starts rising and the coal feed also needs to be increased gradually. Bed

temperature, boiler pressure will now rise fairly fast and as Super-heater pressure

reaches the nominal (rated) value the main steam stop valve is opened to put the boiler

on load after warming up of MS line through by-pass valve.

As the bed temperature crosses 700 º C level, gradually reduce oil flow through HGG

and simultaneously increase main fuel flow to maintain rising trend of bed temperature.

Finally, switch off HGG. Although the oil flow is reduced through HGG, total primary

airflow (combustion air plus dilution air) should not be reduced. In other words dilution

air should be increased to compensate decrease in combustion air linked to fuel oil

quantity. Immediately after HGG switch off, open HGG by-pass damper full. HGG

Bypass Dampers maybe controlled to maintain equal airflow through both HGG’s /

maintaining equal O2 % on both LHS & RHS of Flue Gas, if required.

Once the Boiler stabilizes on Coal, 20% Bamboo Chips, maybe fired by operating the

BCF. Necessary precaution maybe taken while firing bamboo chips by monitoring the

Flue Gas Temperature, to ensure complete ignition of Bamboo chips before exiting the

Furnace.



Page 110 of 177


Bed temperature, especially in low load operation, needs to be controlled by regulating

P.A. /S.A. (In practice it is higher than normal requirement). At higher loads, bed

temperature can be stabilised by operating the cyclone ash screw coolers.



Page 111 of 177

TITLE: STANDARD OPERATION AND LOAD VARIATION

D9 - 0 - 0 - 0 STANDARD OPERATION AND LOAD VARIATION



Page 112 of 177


D9.0.0.0 STANDARD OPERATION AND LOAD VARIATION

As the main fuel firing stabilises, the boiler pressure also gradually rises close to

nominal main steam pressure. First, open by-pass valve of main steam stop valve.

Allow steam to flow for sufficient time to warm up main steam piping. Then open main

steam stop valve and subsequently close by-pass valve.

At this time generally status is:

1) Hot gas generator is switched off.

2) Fuel conveyors and feeders are in service.

3) Bed temperature is at approximately desired level (for coal around

860ºC)

Steam generation from the boiler can be increased or decreased smoothly by regulating

the following:

1) Fuel feed and combustion air

2) Drum level

3) Furnace draft

4) Fluidised bed temperature

5) Steam temperature (especially beyond say 70% of MCR)

D9.1.0.0 FUEL FEED AND COMBUSTION AIR

Normally fuel quantity in bed at any point of time is approximately 3 to 4% of ash

quantity.

Increase in steam supply should promptly increase combustion air (primary and

secondary/tertiary) and the increase in fuel quantity has to follow quickly. Drop in steam

supply should cut down the combustion air promptly and fuel cut has to follow promptly.

Operative behaviour of fuel and combustion air is shown in different diagrams referring

to temperature, pressure and mass flows. Adjusted values of primary, secondary and

tertiary air are maintained by operating personnel or automatic control circuits. The

values of fuel and air will also depend on the fuel characteristics and hence manual

intervention at times becomes necessary in control process.



Page 113 of 177


D9.2.0.0 DRUM LEVEL

Usually three element control, i.e. steam flow, feed flow and drum level, is responsible

to regulate feed water flow and maintain water level in drum reasonably steady.

Occasionally, pressure and temperature corrections are also applied in control circuits.

D9.3.0.0 FURNACE DRAFT

Furnace draft of approximately (-) 30 to (-) 50 mmWC is maintained by regulating ID

Fan speed through VFD, either on manual remote mode or auto mode.

D9.4.0.0 FLUIDISED BED TEMPERATURE

Regulating the bed temperature of CFBC boiler can judiciously control emission of

pollutants, such as CO, NOx. Similarly, where desulphurisation of fuel (like lignite) is

desired by dosing limestone, the reaction takes place in fluidised bed. And the

effectiveness of reaction will depend on bed temperature.

Bed temperature with coal as a fuel should be between 840ºC to 880ºC. The

temperature of circulating ash drops to roughly 400º C during its vertically upward travel

as it enters cyclones. The circulating ash is separated in cyclone by centrifugal action

and it is returned to furnace via siphon. Increase or decrease of the quantity of cyclone

ash (at 400ºC) returned to bed (at approx. 850º C) will correspondingly decrease or

increase the bed temperature from its present level.

At siphon, the branch off for extracting the ash is provided which connects to cyclone

ash screw inlet. The speed regulation of cyclone ash screw cooler governs the bed

temperature.

Coal is charged only after bed temperature rises 20°C beyond fuel ignition temperature.

Boiler is tripped in the event of bed temperature shooting up beyond 940ºC.

Coal feeders/BC feeders may be tripped if bed temperature exceeds 920ºC.



Page 114 of 177

TITLE: STANDARD OPERATION AND LOAD VARIATION D9.5.0.0 STEAM TEMPERATURE CONTROL

At higher load, say above 70% of MCR, mass flow of flue gas and heat absorption in

the Superheaters reach a stage where it is possible not only to achieve final rated

temperature, but it becomes necessary to cool the steam in stages to maintain final

temperature within close limits.

Stage-I Attemperator is interposed between Superheater-I & Superheater-II such that

Superheater-I outlet steam is cooled by the spray of water and enter Superheater-II at a

desired temperature. Stage-II Attemperator is interposed between Superheater-II and

Superheater-III such that steam entering the Superheater-III is cooled by the spray

water and the final steam outlet temperature is controlled to the desired value.

As the load increases, the quantity of water spray also increases. In the event of only

one spray nozzle, it is likely that at higher water flow, atomization of water may not be

proper, which may adversely effect on life of Attemperator. However, multi-spray nozzle

system incorporated in CFBC boiler ensures fine spray of water, within specific limits

through each nozzle, to achieve quick evaporation.



Page 115 of 177

TITLE: ANTICIPATED PERFORMANCE CHARACTERISTICS

D10 - 0 - 0 - 0 ANTICIPATED PERFORMANCE CHARACTERISTICS



Page 116 of 177


D10.0.0.0 ANTICIPATED PERFORMANCE CHARACTERISTICS

1. Boiler Load % Vs Steam Flow (TPH).

2. Air Staging (kg/s) for Coal Grade – F.

3. Air Staging (%) for performance coal.

4. Boiler Load Vs Attemperator Spray flow.

5. Boiler Load % Vs Excess air coefficient

6. Boiler Load % Vs Fuel consumption.

7. Excess Air Vs Excess Oxygen in flue gas.

8. Boiler Load Vs Flue gas Temperature profile.

9. Coal Feeder Speed Vs Coal Flow.

10. Boiler Load Vs Water & Steam Temperature profile.



Page 117 of 177


Boiler Load

0

5

10

15

20

25

30

35

40

45

50

55

60

65

70

75

80

85

90

95

100

0 10 20 30 40 50 60 70 80 90 100 110

Boiler Load (%)

Boi

ler L

oad

(TPH

)



Page 118 of 177


Air Staging (Kg/s)Fuel: Meghalaya Coal

Total Air

Primary Air

Secondary Air

Tertiary Air

0

5

10

15

20

25

30

0 10 20 30 40 50 60 70 80 90 100Boiler Load %

Air

Stag

ing

(Kg/

s)



Page 119 of 177


Air Staging %Fuel: Meghalaya Coal

0

10

20

30

40

50

60

70

80

90

100

110

0 10 20 30 40 50 60 70 80 90 100

Boiler Load (%)

Air

Stag

ing

%

Tertiary Air

Secondary Air

Primary Air



Page 120 of 177


Anticipated Attemperator Spray Water FlowSpray Water Temperature: 230 Deg C

Fuel: Meghalaya Coal

Attemperator # 1

Attemperator # 2

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

60 65 70 75 80 85 90 95 100 105

Boiler Load (%)

Spra

y W

ater

(TPH

)



Page 121 of 177


Excess Air Co-efficientFuel: Meghalaya Coal

1.00

1.10

1.20

1.30

1.40

1.50

1.60

1.70

1.80

1.90

2.00

2.10

2.20

2.30

2.40

2.50

0 10 20 30 40 50 60 70 80 90 100 110

Boiler Load %

Exce

ss A

ir C

o-ef

feci

ent



Page 122 of 177


Anticipated Fuel Consumption (TPH)Fuels: Performance Coal (GCV - 5520 kCal/kg)

Design Coal (GCV- 3345 kCal/kg)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

0 10 20 30 40 50 60 70 80 90 100 110

Boiler Load (%)

Fuel

Con

sum

ptio

n (T

PH)

DESIGN FUEL

PERFORMANCE FUEL



Page 123 of 177


2.0

2.2

2.4

2.6

2.8

3.0

3.2

3.4

3.6

3.8

4.0

4.2

4.4

4.6

4.8

5.0

5.2

5.4

5.6

15 20 25 30 35 40 45

Excess Air %

O2

% W

et (

% b

y V

olum

e)

EXCESS AIR Vs EXCESS OXYGENPerformance Fuel: Indian Coal



Page 124 of 177


Anticipated Flue Gas Temperature ProfilePerformance Fuel: Meghalaya Coal

Screen Inlet

SH3 Inlet

SH2 Inlet

SH1 Inlet

Evaporator Inlet

ECO2 Inlet

Cyclone Inlet

AH Inlet

AH Outlet

Bed Temperature

0.00

50.00

100.00

150.00

200.00

250.00

300.00

350.00

400.00

450.00

500.00

550.00

600.00

650.00

700.00

750.00

800.00

850.00

900.00

950.00

60 65 70 75 80 85 90 95 100

Boiler Load (%)

Flue

Gas

Tem

pera

ture

(Deg

. C)



Page 125 of 177


Fuel Feeder Speed Vs Fuel Feeder FlowFeeder Width = 550 mm ; Bed Height = 180 mm / 80 mm ; Fuel Density = 800 Kg/m3 ; Sprocket PCD = 456.9 mm

Bed Height = 180 mm

Bed Height = 80 mm

0

5

10

15

20

25

30

35

40

45

150 200 250 300 350 400 450 500 550 600 650 700 750

Flow (TPH)

Motor Speed = 750 RPM; Primary Reduction = 40:1 ; Secondary Reduction = 13:38Fuel Flow (TPH) = (Bed Width) m x (Bed Height) m x (Fuel Density) T/m3 x 3.142 x (Sprocket PCD) m x (Feeder RPM) x 60

Mot

or S

peed

(RPM

)



Page 126 of 177


Anticipated Steam & Water Temperature ProfileFuel: Meghalaya Coal

ECO1 In

ECO2 In

ECO2 Out

SH1 In

SH1 Out

SH2 In

SH2 Out

SH3 In

SH3 Out

0

50

100

150

200

250

300

350

400

450

500

550

600

60 65 70 75 80 85 90 95 100

Boiler Load (%)

Tem

pera

ture

(Deg

C)



Page 127 of 177

TITLE: NORMAL/STANDARD SHUT DOWN

D11 - 0 - 0 - 0 NORMAL/STANDARD SHUT-DOWN



Page 128 of 177


D11.1.0.0 NORMAL/STANDARD SHUT DOWN

In principle, the firing can be switched off at any boiler load without a special

preparation. Usually, generation of steam is gradually reduced to minimum load and

then shut down is initiated to bank the steam generator. Refer “SEQUENTIAL START-

UP/SHUTDOWN & BOILER SAFETY INTERLOCKS” (CHAPTER D3-0-0-0). While

pulling out the boiler from service sudden pressure and temperature drops must be

avoided so that pressure parts and non-pressure parts of boiler are spared from thermal

shocks.

D11.2.0.0 BOILER BANKING

Recommended sequence of activities for scheduled short shut down of the boiler is as

under:

1. Reduce fuel feed and steam supply to minimum load

2. Switch off coal feeders

3. "Close" the slide gate damper at coal feeder outlet

4. Switch off PA, SA, ID fans

5. Close the main steam stop valve

6. Raise water level to approximately (+)140 mm in gauge glass

7. Switch off feed water pumps.

D11.3.0.0 BOILER SHUT DOWN FOR LONGER OUTAGES

Follow all steps under "BOILER BANKING" and subsequently:

1. Maintain drum level within (-)200 to (+)140, if necessary, by topping up water

through low feed line. Feed pumps may have to be started for short duration.

2. When the drum pressure comes down up to 2 kg/cm2(g) open "Drum &

Superheater Vent" valves.

3. Natural cooling may be adopted for all boiler surfaces.



Page 129 of 177


D11.4.0.0 BOILER SHUT DOWN FOR PRESSURE PARTS REPAIR WORK BY DRAINING

Follow all steps under "BOILER BANKING" and subsequently:

1. Slowly reduce the drum pressure (according to permissible gradients) by regulating

start up vent valve.

2. Open drum & Superheater vents for residual evaporation at 2 kg/cm2 (g) pressure.

3. Start fans and gradually cool furnace and boiler second pass till gas temperature at

inlet of cyclone reaches around 90° C.

4. Switch off the boiler feed pumps.

5. Initiate draining of the boiler from drum pressure 5 kg/cm2 (g).

6. Switch off the fans.



Page 130 of 177

TITLE: EMERGENCY SHUT DOWN

D12 - 0 - 0 - 0 EMERGENCY SHUT-DOWN



Page 131 of 177

TITLE: EMERGENCY SHUT DOWN

D12.0.0.0 EMERGENCY SHUT DOWN

Boiler could be tripped on account of exceeding safe limits (Min.2 / Max.2 values of

boiler protection) during operation or manually by pressing of the "Emergency Trip”

push button.

Should the pressure starts increasing, open "Start-up Vent" valve partially and reduce

the pressure slightly, say 4 to 5 kg/cm2. Let the boiler cool naturally or initiate forced

cooling, if required (only in emergency), and open drum and super-heater vents when

pressure falls to around 2 to 3 kg/cm2 (g).

Maintain the water level in drum between (+) 140 to (-)150 mmWC.

Now follow the steps under "BOILER BANKING" wherever necessary.



Page 132 of 177

TITLE: REFRACTORY DRYING

D13 - 0 - 0 - 0 REFRACTORY DRYING



Page 133 of 177


D13.0.0.0 INTRODUCTION

Refractory materials applied on furnace walls, air box as well as cyclones plays an

important role in boiler operation. The main objective of refractory is to prevent erosion

of surfaces especially of furnace and cyclones where expensive low castable is applied.

Besides, it prevents wastage of heat, and helps desired heat transfer in lower portion of

furnace. Natural drying will have no doubt removed part of the moisture in refractory.

Remaining moisture as well as chemically combined water has to be removed slowly so

that it is cured without giving rise to big cracks in settings.

D13.1.0.0 METHODOLOGY

The boiler is drained completely before both hot gas generators are lit up to start

refractory drying. In order to ensure slow heating from ambient temperature, oil guns /

sprayer plates of lower capacity say 250 litres (max) per HGG should be used. Keeping

the oil consumption at low level initially at around 100 Ltrs /hr, the rise in temperature of

flue gases at screen inlet can be maintained at about 20°C/hr. The heat absorption of

pressure part steel is negligible unlike the water filled furnace walls. The temperature

gradient between air box to cyclone is also small. Once flue gas temperature reaches

approximately 110°C, control the rate of oil consumption so that soaking can be done

for about 36 hours at this level. This will slowly evaporate the moisture.

Raise the temperature of flue gases by slow increase in oil consumption at the HGG so

that a gradient of 20°C per hour is achieved from 110°C up to 220°C temperature. Soak

the refractory at 220°C approximately for 18 hours.

Shut down the HGG and allow the natural cooling of refractory after 18 hours of soaking

at 220°C. This marks the end of first phase of refractory drying.

Second phase of refractory drying is taken up at the commencement coal/lignite firing.

Raise the bed temperature with the help of HGG at the rate of 15°C per hour when the

bed material is in furnace, which is filled with water. Soaking may be done for approx

12 hours maintaining bed temperature 500°C to 550°C.



Page 134 of 177


The refractory drying is concluded now and we can proceed with normal operation like

charging coal etc.

In order to achieve proper curing of cyclone refractory, a small flue modification is

carried out so that flue gases do not escape via coal-ash pipes, and siphon. The blanks

on coal pipes may be retained during alkali boil out, steam line blowing etc and removed

after bed material is charged in furnace. Closing plate between cyclone outlet and

Economiser I as well as bye pass duct short circuiting cyclone bottom to Air heater may

be removed after first phase of refractory drying is concluded.

0

55

110

165

220

275

330

0 6 12 18 24 30 36 42 48 54 60 66 72 78 84Time in Hours

Te

mp

. in

De

g.C



Page 135 of 177

TITLE: ALKALI BOIL OUT

D14 - 0 - 0 - 0 ALKALI BOIL OUT



Page 136 of 177


D14.1.0.0 PURPOSE

The cleaning of internal surfaces of furnace pressure parts is essential to ensure that

during normal operation of steam generation, steam is free from impurities/foreign

particles such as lubricants, oil, rust, sand, metal fragments and assorted debris which

are harmful for steam consumers e.g. steam turbine. This is achieved by boiling

out/circulating alkaline solutions through part of pressure parts.

As preparatory to boil out process, flushing of the boiler is carried out by repeated filling

up of steam generator and draining. Treated (completely desalinated or softened) and

deaerated feed water should be used as filling water for flushing and through out alkali

boil out operation.

D14.2.0.0 CHEMICALS

The following chemicals should be added through steam drum manhole just before

commencement of heating by hot gas generators. Quantities are for each cubic metre

of water in the system.

Anhydrous Trisodium Phosphate (Na3PO4) : 2 kg

OR

Crystalline Trisodium Phosphate (Na3PO4, 12H2O) : 5 kg

OR

Soda Ash (Na2CO3) : 9 kg

1.5 kg to 2 kg of good detergent may also be mixed with water in addition to quantity of

one of the chemicals stated above.

Water holding capacity (up to steam drum centreline) ~ 36 Te.

Provision should be made for double quantities of chemicals. Mostly, two charges of

chemicals may not be necessary.



Page 137 of 177


Open the steam drum manhole door and feed water through filling line until water is

about 150 mm below the bottom of steam drum manhole opening. Boiler is lighted up to

raise water temperature to approx. 900C. Dissolve the chemicals thoroughly in hot

water in a suitable tank or container and transfer the solution into the drum via manhole,

ensure the chemicals are evenly distributed across the drum. Do not pour the solution

in empty boiler drum. After charging solution (of chemicals), slowly feed the water in

system to assist mixing. Close and secure drum manhole door and finally take water in

system to bring water level up to approx 100mm below centre-line of gauge glass.

D14.3.0.0 PROCEDURE

Start hot gas generators with fuel at minimum level. Soon after the HGG is switched on,

the boiler is thermally "Alive". During the initial warming up, temperature changes

through out, the unit may indicate places where expansion strains are felt or where

warming up of headers and drum are not occurring uniformly. Keep close watch on

such undesirable developments. The following items should be observed:

1. Thermal expansion of casing and buck-stays.

2. Boiler circulation starts soon after a fire is lit in the combustor. Top headers

and drum will get warmer first to be followed by lower portion of furnace and

bottom headers. In case a particular header or a portion of it shows signs of

non-uniform heating, give number of short blows (max 20secs) through the

header drain /blow down valves until the circulation is observed/noted. Blow

down from each header should be roughly same quantity.

3. Expansion joints remain tight and unrestrained.

4. Boiler is expanding in different directions as desired.

(Trams are already fixed at various levels and locations for monitoring thermal

expansion)

The steam generator is heated up with a firing capacity of approx. 3 to 5% MCR to

reach boiling condition and later on approx. 7% MCR up to about 30 Kg/cm2 (g) working

pressure. Both hot gas generators may be pressed in service for boil out operation.

Start up vent and Super-heater drain will be partially open to maintain pressure and

small circulation. The flue gas temperature at SH3 entry should not exceed 450-480°C

(fuel quantity limitation).



Page 138 of 177


Air vents should be shut off as soon as strong blow of steam occurs, at about 2 Kg/cm2

Boiler pressure. (The drum pressure gauges impulse lines may be blown through for

commissioning drum pressure gauge). As the pressure is raised, carefully inspect drum

manhole joints for leaks and tighten where necessary.

The water level in drum will normally increase due to expansion of water and circulation

and occasionally, the level touches top of gauge glass. Under these conditions the

excess water should be removed by operating lower water wall header drain valves. By

removing water from the boiler at this location, circulation can be accelerated.

It is desirable to warm up the boiler by continuous (controlled) firing because circulation

can be maintained continuously, thus assuring uniform heating of all pressure parts and

minimum of stress to them as well as refractory. When raising steam pressure with

intermittent firing, it is possible to arrive at full operating pressure in steam drum and still

have lower portions of boiler, remain relatively cool.

Around 30 kg/cm2(g) pressure in boiler will produce adequate circulation. Maintain this

pressure for 10 hours or longer. It is permissible to throttle vent to conserve fuel.

However ensure that sufficient steam is generated to have active continuous boiling of

solution and corresponding circulation of boiler water.

During boil out, furnace bottom header drain blow down valves should each be opened

for approximately five seconds at after every two hours interval. This will remove

maximum of sludge with minimum of risk of choking the blow down pipe work. Collect

Boiler water sample (CBD sample) for analysis of (a) Phosphate concentration, (b)

Alkalinity, and (c) Oil & Grease content in the sample. During the process, if the

phosphate concentration drops below 2000 ppm, doze additional chemicals through HP

dozing system to restore the original concentration.

Blow down lines should be hot. If not give them additional short blow down until they

become hot. Add clean warm water to bring back normal water level, bring the pressure

back to boil out pressure and continue boiling with steam venting.



Page 139 of 177


D14.4.0.0 CLEANING AND INSPECTION

After maintaining the drum pressure around 30 kg/cm² (g) and normal circulation for

about 20 hours, shut down the HGG. Give blow down for longer period. Water level

should be restored and maintained until the boiler cools. When the boiler has finally

cooled, but before zero pressure is reached (say 6Kg/cm2) open all blow down and

drain valves to hot drain the boiler, economiser and super-heater. Open all air vents

when the pressure reaches 2 Kg/cm2. During emptying check that each drain and blow

down is running clear and it is not choked. On completion, feed a little water into the

boiler to wash out any remaining sludge.

Repeat blowing down and refilling the boiler at every two hours intervals. After alkali

boil out, periodically take blow down samples and analyse for oil content, silica, pH,

phosphate, suspended matter and clarity, if laboratory facilities are available. Continue

draining and refilling till quality of circulated water has conductivity within 50 micro-mho

of the incoming water. If analytical equipment is not available, charging and draining

water every two hours can be terminated when clarity or turbidity of drained water is

visibly same as the incoming water.

Inspect the interior of the steam drum, lower water wall headers and all other accessible

internal surfaces. Wash out any loose scale or other residue seen on internal surface of

the drum with high-pressure water hoses. The inspection nipples of furnace bottom

headers and economiser inlet header should be cut to examine bottom headers for left

over sludge/sediment. Remove all foreign material by washing with high-pressure water

hoses. The inspection nipples should now be rewelded and post heat treatment

wherever necessary carried out. Drum internals should now be fixed.

When all cleaning operations are completed and inspection confirms that internal

surfaces are clean, install new gaskets on any gasketed openings that were used for

access.

Unit is now ready for steam line blowing.

It should be the responsibility of nominated competent individual to control water level

(bearing in mind that alarms and remote indicators available in normal service are not

pressed in service during this operation) and rate of change of pressure and

temperature. Adjust drain quantities such that no excessive pressure drop occurs while

opening the drain valves.



Page 140 of 177

TITLE: STEAM LINE BLOWING

D15 - 0 - 0 - 0 STEAM LINE BLOWING



Page 141 of 177


D15.1.0.0 PURPOSE

High velocity boiler steam is often used to clean the Superheaters and steam piping

which may contain mill scales, and any loose material that may damage the turbine

valves, blades or nozzles. Temporary exhaust piping is attached to the steam line near

the turbine so that the loose material can be discharged into the atmosphere without

allowing it to enter the turbine. After the blowing operation is completed and the

temporary piping is removed, fine mesh screens are often installed at the turbine inlet

and left in place during the preliminary operation or until inspections show no debris

collected on them.

Various piping and valve arrangements are used, but the basic scheme and

requirements are shown in a Figure-1 below.



Page 142 of 177


There are certain items that must be incorporated in the design of the temporary piping

and valves on all units. These are:

1. The temporary piping, valves and flanges must be designed for the pressure

used during the blowing periods.

2. The temporary atmospheric exhaust must be well supported to withstand the

reaction forces created during the blowing period.

3. The nozzle should also be directed so that the debris discharged at high velocity

during the blowing period does not endanger personnel and equipment.

4. The temporary exhaust pipe bore should be at least as large as the existing

steam piping so that steam flow is not restricted.

5. All NRV internals, control valves, flow nozzles and orifice plates, if any, in the

blow circuits are to be removed and spool pieces to be provided.

6. All permanent hangers and supports for various lines are to be erected and set

for proper values as per design figures. All locks and restraints are to be

removed from pipelines.

7. The area around the exhaust point should be cordoned off. For warning sound,

prior to blow, siren or public address system can be utilised.

8. Boiler should be ready in all respects including:

a. Interlocks, protections, alarms, annunciation and instruments

b. Chemical dosing system

c. Insulation of furnace and air & flue gas ducts

d. Fire fighting system as per designed scheme

e. Fuel oil firing equipment

9. Chemical cleaning of pressure parts internals must be complete prior to steam

blowing.

10. All drain connecting pipes on MS line are to be left open to atmosphere and are

not to be connected to drain vessel to ensure proper and quick draining. After

checking drain pots for choking, the drain lines are to be connected permanently

to vessels after steam blowing.

Note:

All piping, various supports, exhaust steam regulating valve and other valves connected

to turbine and related to steam blowing are not in TKIIPL's scope unless it is specifically

included in contract.



Page 143 of 177


D15.2.0.0 PROCEDURE

One procedure for blowing is to raise the boiler pressure to a value slightly below the

design pressure of the temporary piping, gradually open the steam regulating valve

while increasing the firing rate to maintain pressure during the blow and gradually close

the regulating valve while reducing the firing rate. Long blowing periods can be

maintained with this procedure.

An alternate procedure is to raise boiler pressure to a value slightly below the design

pressure of the temporary piping, shut off the firing, open the regulating valve quickly

and permit the boiler pressure to drop to a pressure which will result in a saturation

temperature drop not exceeding 40ºC, then quickly close the regulating valve. This

procedure results in sudden temperature changes, which helps to loosen scale from

inside the steam piping. However, all the boiler pressure parts are subjected to the

same temperature shock. The 40ºC change in temperature during the blowing period

has been established to prevent excessive stresses to the steam drum. Because of the

limited blowing period permitted by this procedure, a number of blows may be required

to do a thorough cleaning job.

In practice, usually the boiler pressure is raised to 40 kg/cm2. Trip the firing and quickly

open the blow off valve.

Allow drum pressure to drop down to approximately 20 kg/cm2 and quickly close the

blow off valve.

The interval between successive blows will be approximately 2 hours. In a day normally

about 6 to 8 blows maybe given with Overnight shutdown of the boiler for about 8 hrs.

This will help in loosening the Mill scale due to cooling and contraction.

All the permanent main steam piping must be insulated before commencing the steam

blowing operation.

All permanent hangers are in position and pressed in operation after floating.

All equipment and personnel around temporary steam piping/supports must be guarded

against any damage /injury.



Page 144 of 177


Observe all of the precautions used for normal start-up and normal operation, namely,

purge the furnace, do not exceed drum temperature differential limits throughout the

pressure raising and blowing periods, and maintain adequate water level in the boiler.

Sufficient feed-water pump capacity and condensate storage must be available to

replace the water loss during the blowing period. The water level in the boiler must be

kept under proper control at all times. The water level will rise sharply at the beginning

of each blow and fall sharply at the ending of each blow with the rate of level change

following the rate of valve openings in the steam lines.

The boiler pressure used for blowing out the line must not exceed, the design pressure

of the temporary piping, valves and flanges. Many operators prefer low-pressure

saturated steam or slightly wet steam at high velocities. Velocities above normal

operating velocities can be obtained with low-pressure steam because of the great

change in specific volume of the steam. Other operators feel that temperature shocks,

along with high velocities are required to loosen scale inside the steam piping.

The colour of the steam discharged to the atmosphere can be used as an indication of

the debris being removed from the piping. The abrasion of aluminium target plates

(used in early stages and polished S.S. target plate is used at later stage) at the end of

the exhaust piping gives an indication of amount of debris removed during the blowing

operation. These target plates can be inspected for progressive abrasion after each

blow or they can be replaced after each blow.

In selecting the blowing pressure, it must be remembered that high velocities are easily

obtained with low pressure but changes in drum water level, on the other hand, are

minimized if higher blowing pressures are used.



Page 145 of 177

TITLE: STEAM LINE BLOWING D15.3.0.0 DISTURBANCE FACTOR

Disturbance Factor will be calculated using the formulae:

W2purge X Vpurge

Disturbance Factor (DF) = ------------------------

W2MCR X VMCR

Where,

Wpurge = Mass flow during purge condition. This shall be calculated using

Lapple’s equation for compressible fluids.

Vpurge = Specific volume of steam at purge parameters.

WMCR = Steam flow at MCR

VMCR = Specific volume of steam at MCR.

The value of DF at selected locations should be in the range 1.7 > DF > 1.3

D15.4.0.0 COMPLETION CRITERIA

Steam blowing can be declared complete only after ensuring cleanliness of target plates

mounted in the temporary exhaust pipe.

The highest velocity of steam being at the centre, the effectiveness of steam blowing is

judged by the absolute pitting on the Target plate in the central zone i.e. the area

covered by 3/4th of the diameter.

The piping is considered clean if there are not more than five (5) pitting on the target

plate central zone and the edges are not deformed. Besides there should be no pitting

on the rim zone i.e. the area other than the central zone. This should be achieved on 3

consecutive plates.



Page 146 of 177

TITLE: SETTING OF SAFETY VALVES

D16 - 0 - 0 - 0 SETTING OF SAFETY VALVES



Page 147 of 177


D16.1.0.0 GENERAL

All safety valves are set for popping pressure and blow down before despatch from

manufacturer's works. However, possibility of slight disturbance from desired settings

cannot be ruled out on account of:

1) Physical layout of inlet and outlet piping, drain connections and supports.

Incorrect layout may generate high stresses and back pressure.

2) Ambient temperature.

3) Quality of steam.

4) Any damage during transit, storage or installation.

5) Rust, dirt or foreign material trapped in safety valve components during

storage.

It is therefore necessary to dismantle the safety valve, service it and assemble it

properly. For this purpose, the operation and maintenance instructions of manufacturer

must be thoroughly studied before setting out to float safety valves. Exact position of

compression nut, upper adjustment ring, lower adjustment ring etc. must be properly

recorded in "as received condition". Ensure same setting after servicing and assembly.

Use "Molykote" to lubricate threaded components and areas recommended by

manufacturer.

D16.2.0.0 PRECAUTIONS AND SAFETY MEASURES:

1) Use earmuffs when you are near to safety valves during adjustment.

2) Do not stand close to discharge pipes of safety valves

3) Gagging of safety valve is must while making ring adjustment.

4) Use hand gloves to protect from hot safety valve

5) Make sure that valve body and discharge elbow is free from external stresses

passed on from discharge piping. Safety valves escape piping supports must

be as per drawing.

6) During the boiler hydraulic test at 1.5 times the design pressure the hydrostatic

plugs must be in place. In addition, gag all safety valves.

7) Under no circumstances, the hydraulic test pressure should exceed design

pressure of the boiler unless hydrostatic plugs are in place.



Page 148 of 177

TITLE : SETTING OF SAFETY VALVES

8) Fix the gags on safety valves while raising the system pressure at

approximately 80% of design pressure. Similarly, gags should be removed at

approximately 80% of design pressure while releasing the system pressure. in

our case, design pressure is 120 kg/cm² (g).

9) Drain connections from body of safety valve, exhaust elbow, drip pan and

cover vent up to tundish should not have upward slope in any circumstances.

Ensure correct supporting arrangement for drain piping.

D16.3.0.0 PROCEDURE OF SAFETY VALVES FLOATING

Keep water level in drum approximately 150 mm below NWL.

Light up the boiler and raise the pressure at the normal rate (without exceeding

pressure raising curve limits). Gag all valves, except the one, which is being tried for

checking the setting, when pressure reaches around 80% of pop up pressure of lowest

set valve. Usually the Safety Valve with the highest Set Pressure is floated first.

Position the gags properly and tighten them with only light force applied to the gag stem.

Gagging of safety valves in cold condition or low pressure is risky.

Ensure that no person is within 5 metres radius from specific valve under testing. Tie a

rope to the hand lever of safety valve and pull it clean for hand pop up at around 90 to

95% of rated pressure. Give one or two hand pops to remove any dirt/impurities left in

body/inlet of safety valve.

When safety valves are being floated, the water level should be kept below half gauge

glass, feed water should be available at the regulating valve, and the Superheater

drains should be opened. Raise the boiler pressure and allow the safety valve to lift on

its own. During this period it is advantageous to accelerate pressure-raising rate, for

clean pop. Safety valve may simmer when the boiler pressure is very close to the set

value.

The valves should be individually set within +1% of set pressure. The blow down

should be 3 to 5% of set pressure. In case of deviation, adjustment of compression nut,

upper ring and lower ring should be carried out only after lowering the system pressure

to about 80% of rated value and precisely as per instructions of safety valve

manufacturer.



Page 149 of 177


Soon after safety valve floats, kill the fire and open the start up vent (partially) to reduce

the pressure in the boiler. Initially, water level may swell but with each safety valve

floating, fresh warm water will have to be admitted to bring up water level in the drum.

Just in case boiler pressure exceeds 1% beyond set value and even then safety valve

does not pop up, kill the fire and open start up vent partially to reduce the pressure to

about 80% of rated value for carrying out corrections.

Successive floating of same safety valve in the event of unsatisfactory performance viz.

pop up pressure or blow down should be avoided. After the boiler pressure drops to

about 80% of pop up pressure (subsequent to safety valve floating) gags may be

interchanged and second safety valve (for its respective setting) may be tried. This will

save time and allow sufficient cooling of safety valve.

In any case ensure that at least one hour of cooling time is provided between

successive floating of same safety valve.

D16.4.0.0 DEFINITIONS

Set Pressure is that predetermined pressure above the working pressure of the boiler

that gives an adequate margin of pressure difference to prevent unnecessary

simmering. It is the pressure at which the first audible sound of escaping steam is heard

and Not the Pressure at which the valve lifts fully.

Full Lift Pressure is that pressure at which the valve has reached its maximum lift and

is usually within 3% excess of the set pressure.

Closing Pressure is that pressure at which the valve re-sets.

Blow-down is the difference between the set pressure and the closing pressure and

should be within 3 – 5 % of the set pressure.

Blowdown = (Set Pressure) – (Closing Pressure) X 100%

(Set Pressure)



Page 150 of 177

TITLE: PRESERVATION OF BOILER

D17 - 0 - 0 - 0 PRESERVATION OF BOILER



Page 151 of 177



The advantages of efficient feed water and boiler water treatment during operation may

be lost if the same diligence is not applied to protect heat transfer surfaces during idle

periods. Protection from corrosion during storage becomes vitally important considering

the number of times the boiler and its auxiliary equipment will be idle during its life. To

minimize the possibility of corrosion, boilers to be put into the storage must be carefully

prepared for the idle period and closely watched during the outage.

There are two methods available for storing the unit i.e. dry storage and wet storage.

Although the wet storage procedure is preferred, factors such as availability of good

quality water, ambient weather conditions, length of storage period, auxiliary supply of

heat etc., may dictate that the dry storage procedure is more practical. When the unit is

required for standby service and must be held for sudden calls for operation and the unit

can be quickly made ready for placing in service, wet storage method is adopted.

D17.2.0.0 DRY STORAGE

When it is known that a boiler is to be idle for a considerable length of time and that a

brief period will be allowed for preparation to return it to service, the dry storage method

is recommended. In this method, the unit is emptied, thoroughly cleaned internally and

externally, dried, and then closed up tight to exclude both moisture and air. Trays of

lime, silica gel, or other moisture absorbent may be placed in the drums to draw off the

moisture in the air trapped by the closing up of the boiler. The following general

procedure is recommended when placing a unit into dry storage:

1. Fire the boiler according to the normal start-up procedure and establish 3.5

kg/cm² (g) drum pressure. Secure the boiler and when the pressure decays to

1.5 kg/cm²(g), drain immediately under air. As soon as possible, open the

drums to allow air to circulate for drying of all internal surfaces. This step is

included for a unit that has been in service and is to be placed into storage.

For a unit, that has never been in service, start with Step 2.



Page 152 of 177

TITLE: PRESERVATION OF BOILER 2. If the unit is full of water, drain the unit under air. All non-drainable boiler tubes

and super-heater tubes should be blown with compressed air. If an external

source of heat is available such as a steam coiled air heater, portable heaters,

etc., operate these heaters to assist in drying the internal surfaces. Install a

tray containing moisture absorbent (silica gel is preferred) into the drums. To

insure against overflow of corrosive liquid after the moisture has been

absorbed, the trays should not be more than 3/4 full of dry absorbent. The

amount of moisture absorbent can vary but one Kilogram per Tonne/hour

steam flow capacity is a suggested minimum.

3. Attach a source of nitrogen to the steam drum vent, close all other vents and

drains and pressurize the boiler to 0.7 to 1.0 kg/cm²(g) with nitrogen. The

amount of nitrogen required will vary according to the volume of the unit.

4. With the boiler and super-heater pressurized, alternately open all boiler drains

(including super-heater) to purge air from the unit until pressure decays to zero.

It may be necessary to repeat this process several times to reduce the amount

of oxygen left in the unit to a minimum.

5. The unit should now be stored under 0.3 to 0.7 kg/cm² (g) nitrogen pressure

maintained at the steam drum.

6. We would recommend that periodic inspection of the unit be performed every 3

to 6 months to assure that no corrosive action is taking place and to replenish

the absorbent as required. Since air will enter the unit during this inspection, it

will be necessary to repeat Steps 3 and 4 to expel the air.

CAUTION:

THE UNIT SHOULD BE PROPERLY TAGGED AND THE APPROPRIATE WARNING SIGNS

ATTACHED NOTING THAT THE BOILER IS STORED UNDER NITROGEN PRESSURE AND

THAT COMPLETE EXHAUSTION OF THE NITROGEN MUST OCCUR BEFORE ANYONE

ENTERS THE DRUM. BEFORE ENTERING DRUM, TEST TO PROVE THAT THE OXYGEN

CONCENTRATION IS AT LEAST 19.5 PERCENT.

The above procedure is intended to include the economizer and super-heater.



Page 153 of 177


D17.3.0.0 WET STORAGE

The advantage of employing the wet storage procedure is that the unit is stored

completely wet with the recommended levels of chemicals to eliminate a wet dry

interface where possible corrosion can occur. It is suggested that volatile chemicals be

used to avoid increasing the level of dissolved solids in the water to be used for storage.

In preparing a unit for wet storage, the following procedure is recommended.

1. The unit should be filled with deaerated, demineralised water treated with 200

ppm hydrazine (N2H4) for oxygen removal and sufficient ammonia (NH3) to

attain a pH of 10 (for demineralised water, this will require approximately 10

ppm ammonia).

2. We strongly recommend pre-mixing of the chemicals with the water to insure a

uniform mixture entering the boiler. This can be accomplished by the blend-fill

method, or if possible, by pre-mixing of the chemicals in the condenser. Simply

introducing the chemicals through the drum manhole after established water

level will not insure adequate dispersion of chemicals to all internal surfaces,

unless sufficient heat is delivered to the furnace (i.e. firing the boiler) to induce

natural circulation throughout the boiler.

3. Fill the unit with the treated demineralised water until flooding occurs at the

steam drum vent.

4. Back fill the Superheater with treated demineralised water.

5. A source of low-pressure nitrogen should be connected at the steam drum to

maintain 0.3 to 0.7 kg/cm²(g) pressure to prevent air entering the unit.

CAUTION:




ENTERS THE DRUM. BEFORE ENTERING DRUM, TEST TO PROVE THAT THE OXYGEN




Page 154 of 177


6. If storage continues into winter, ambient temperatures below the freezing point

of water create a real hazard to the boiler pressure parts and it will be

necessary to provide a means of keeping the unit warm to avoid damage.

7. At some later date when the unit is to be placed into service, the boiler can be

drained to normal start-up water level and placed into operation.

In some cases, an expansion tank or surge tank above the drum and super-heater

elevation may be required to accommodate volume changes due to temperature

changes. The ammonia and hydrazine are not required for short period of storage of

less than two weeks; however, the nitrogen blanket is recommended for the steam drum

and super-heater.

Even with the above procedures, the possibility of corrosion must not be

underestimated. The boiler should be inspected periodically for possible corrosion

damage. Analysis of the boiler water should be conducted periodically and, when

necessary, sufficient chemicals added to establish the proper levels recommended. To

ensure uniform dispersion of the chemicals, it will be necessary to repeat one of the

methods outlined in Step 2.

Super-heaters during out-of-service periods, except when the wet storage method is

used, should always be kept dry and closed from contact with air.

No unit should be stored wet when there is any possibility of a temperature drop to the

freezing point unless sufficient heat can be provided to the unit to eliminate the danger

of water freezing and subsequent damage to pressure parts.

Storage of the pre-boiler piping systems, whether it is wet or dry, can be handled in a

manner similar to those suggested for the boiler.



Page 155 of 177

TITLE: PRESERVATION OF BOILER D17.4.0.0 NITROGEN BLANKET

Nitrogen should be introduced through a "T" fitting or one vent (or drain) at each of the

following locations:

1. Drum vents

2. Crossover piping vent between primary and secondary super-heater.

3. Secondary super-heater outlet header connection.

The "T" fitting is to be installed between the pipe (or header) and the vent (or drain)

valve. The nitrogen inlet to the "T" should include a stop valve identical to the vent (or

drain) valve. The stop valve and "T" fitting should be a permanent addition to the

location listed.

The nitrogen required to seal the drainable components may be supplied from a

permanent nitrogen system or portable tanks located near the vent elevations. Due to

differences in plant layout, the owner should choose his own method of piping the

nitrogen, either from their permanent system for from portable tanks, to the vent (or

drain) locations listed.

CAUTION:




ENTERS THE DRUM. BEFORE ENTERING DRUMS TEST TO PROVE THAT THE OXYGEN


D17.5.0.0 PROTECTION OF EXTERNAL SURFACES Gas side corrosion of an idle boiler can cause considerable damage, especially to the

ash hoppers, expansion joints, dampers, boiler casing, fuel burning equipment, baffles,

and flues and ducts. Flue dust, ash, slag, or cinders from sulphur bearing fuels contain

sulphuric acid. When moisture is added, a dilute acid is formed which is very corrosive.

In preparing the boiler for Storage these accumulations must be removed by either

blowing with air lances, washing with water, scraping, or brushing.



Page 156 of 177


In most cases the deposits cannot be completely removed by mechanical means and

therefore must be neutralized with alkaline water. The alkaline flush should be continued

until the water leaving the boiler is completely neutralized. Litmus paper may be used to

determine the acidity of the wash leaving the boiler.

After the flushing operation has been completed, the boiler should be filled with treated

water and fired with a low sulphur fuel to completely dry the setting.

In areas with extremely corrosive atmosphere, all machined surfaces on fuel burning

equipment should be protected with a preservative coating.



Page 157 of 177

TITLE: WATER TREATMENT

D18 - 0 - 0 - 0 WATER TREATMENT



Page 158 of 177

TITLE : WATER TREATMENT


The water is taken from raw water reservoir and then it is transferred to water treatment

plant by raw water transfer pumps. Requisite Alums are added. The chlorinated raw

water is then suitably pre-treated prior to feeding to the DM or Softener unit. The pre

Treatment section consist of Chemical dosing and Multi grade filters (MGF). The silica

& turbidity level in the feed water is reduced by filtration. The filters are back washed

after 20 hours of service cycle. (During filter backwash, the DM plant and Softening

plant will be out of service mode and standby is taken into service). The filtered water is

then de-chlorinated with ACF or by stand-by Sodium meta-bi-sulfite dosing. The de-

chlorinated water is then passed to softener and DM stream.

The softening plant consists of Softener exchanger (sodium based ionexchanger), soft

water storage tank and soft water transfer pump sets for cooling water cycle make-up.

The Demineralisation plant consists of RO Plant, Degasser, Degassed Water Tank,

Mixed Bed Exchanger, DM water storage tank and DM water transfer pump sets. The

outlet quality of DM water will correspond to boiler make-up water quality requirement

Maintenance of internal and external surfaces of pressure part tubes/pipes in healthy

condition is essential to achieve high load factor and long life of any boiler. Deposition

of insoluble material on internal surfaces of water and steam tubes/pipes influence heat

transfer adversely and sometimes results in tube failures. Treatment of water should

therefore be in its entirety i.e. from raw water to quality of steam in terms of impurities.

Working pressure of water and steam at different stages also significantly affect rate of

reaction and solubility of chemicals used in water treatment. Higher operating pressure

and temperature of boiler call for further stringent requirements and closer limits on

tolerance. Water treatment system is provided to ensure quality of water at feed water

entry point and also take care of dosing appropriate chemicals at low pressure and high

pressure in steam drum to ensure that impurities are within specified limits given in VGB

or similar internationally accepted code.

Present day practice in water treatment technology suitable for the CIRCOFLUID boilers

generating steam at about 90 to 120 kg/cm²(g) pressure and 500°C plus temperature is

generally discussed in the following pages to serve as guideline only.



Page 159 of 177


D18.2.0.0 OXYGEN CORROSION OF INTERNAL SURFACES

Carbon steel is protected by a fundamental iron-water chemical reaction that forms a

protective film of magnetic iron oxide on the internal metal surfaces. A small amount of

iron reacts with water until the protective oxide film is formed. Once the film is

established, the reaction virtually stops and does not resume until the film is disturbed or

removed. If the film is removed chemically or mechanically, the iron-water reaction

starts again to build up the protective oxide. This, of course, removes more iron from

the surface of the boiler parts and if allowed to continue will definitely thin the metal

parts. It is, therefore, very important to maintain boiler water chemistry within close

limits to prevent the chemical removal of the initial protective magnetic iron oxide film on

the internal metal surfaces.

The most common form of corrosion is that caused by the presence of oxygen in the

water-steam cycle. The most logical approach to the prevention of corrosion due to

dissolved oxygen is to eliminate the entrance of oxygen to the cycle as far as possible

and by expelling at the first opportunity the oxygen which has unavoidably entered the

cycle. The most common method of expelling oxygen is by deaerating the feed-water

from heaters or condenser.

It is of the utmost importance that this equipment should function over full load range of

the boiler. Oxygen concentrations at the deaerator outlet should be consistently less

than .007ppm. As a further assurance against the destructive effect of dissolved

oxygen, sufficient quantities of oxygen scavenging chemical compound should be

added to the feed-water after the deaerator to maintain a residual of chemicals in the

boiler water. The residual is an indication that all oxygen has been removed; it is also

available for upset conditions.



Page 160 of 177


D18.3.0.0 HYDRAZINE AND SODIUM SULPHITE

Reaction of hydrazine with dissolved oxygen produces nitrogen and water. Even

products of decomposition of hydrazine are volatile and tend to form, alkaline solutions

with water. This, therefore do not increase dissolved solids content in boiler water. The

reaction is of course dependant on hydrazine concentration, temperature and time. Due

to the volatility of hydrazine and its decomposition at elevated temperatures, only a

small residual (a few hundredths of a part per million) can be maintained in the boiler

water. It is apparent that with this small quantity of hydrazine available only minute

amounts of oxygen can be allowed to enter the boiler system.

Sodium sulphite is another chemical commonly used in low-pressure boilers as oxygen

scavenger. Sodium sulphate formed after its reaction with traces of oxygen is relatively

harmless chemical. It is advisable to inject sodium sulphite solution in the feed pipe

downstream of Attemperator take off point and upstream Feed Control station to be

assured that boiler salt does not accumulate in steam circuit after evaporation and at the

same time increase feasibility of oxygen scavenging from feed control station piping,

economiser etc.

Products of thermal decomposition at higher operating pressures of boiler are hydrogen

sulphide and sulphur dioxide.

These will re-dissolve at a point where condensation of steam occurs leading to acidic

condition in water circuit. Hydrazine is therefore preferred as oxygen scavenger in the

boiler operating in the region of 100 bars pressure.



Page 161 of 177


D18.4.0.0 pH CONTROL OF CONDENSATE FEEDWATER

In accordance with Table-I, feed-water pH should be controlled in the range of 8.5 - 9.5

to reduce iron and copper pick-up in the condensate - feed-water system. The most

common neutralizing chemicals used for controlling the pH of the condensate - feed-

water are - Ammonia, Morpholine, Cyclohexylamine, and Hydrazine.

These chemicals are volatile alkalizers, which distil with the steam and neutralize trace

acids formed in the condensate. Hydrazine is included with the volatile alkalizers,

besides being an oxygen scavenger; it decomposes at the operating temperature of the

boiler (beginning at 200º C) into ammonia in accordance with the following reaction:

Hydrazine -------- Nitrogen + Hydrogen + Ammonia

2N2H4 -------- N2 + H2 + 2NH3

Experience has shown that the condensate pH, when using hydrazine, will stabilize in

the range of 8.5 -9.5 (due to the ammonia formation) depending upon the residual of

hydrazine maintained at the economiser inlet.

Proper pH control and selection of neutralizing chemical can only be determined by a

critical study of the materials making up the condensate feed-water system and on the

basis of iron and copper concentrations in the feed-water which would be indicative of

the attack on these cycle materials. Limits for iron and copper concentrations in the

feed-water are included in the Table-1 given below.

In general, a high pH (due to the ammonia concentration) is considered more

aggressive to copper bearing alloys but is more protective to the carbon steel surfaces.

Therefore, in a cycle consisting of both carbon steel and the copper bearing materials,

of varying quantities, the proper pH can only be prescribed after some experimentation.



Page 162 of 177


Of the above alkalizers, morpholine has the most favourable vapour to liquid distribution

ratio; that is, it readily dissolves in the first condensate forming in the turbine,

condenser, feedwater heaters, etc. Its decomposition temperature is in excess of

520ºC. If higher steam temperatures are encountered, formation of ammonia in the

cycle will increase. The decomposition products of morpholine and cyclohexylamine

yield small quantities of ammonia.

When feed-water or boiler water conditions are changed suddenly and drastically,

temporary upsets may be produced which can be troublesome. Therefore, any changes

such as an alteration in the feed-water treating practice, should be made gradually and

with close observation. When hydrazine feed is first started, initial dosage should be

small and changes in the iron and copper concentration in the feed-water should be

carefully monitored. If iron and copper concentration in the feed-water and boiler water

increase significantly, boiler blow-down should be increased. Since it sometimes

requires days or weeks for conditions to stabilize, results must be observed over a

significant period before effects can be properly evaluated.

D18.5.0.0 CARRY-OVER

The trend toward higher steam pressures and temperatures resulting in higher operating

efficiencies imposes a great demand from steam purification equipment to eliminate

troublesome turbine deposits caused by carry-over. Carry-over may result from

mechanical means and/or vaporization of the boiler water salts.

Mechanical carry-over is the entrainment of small droplets of boiler water in the

separated steam. Since entrained boiler water droplets contains solids in the same

concentration and proportions as the boiler water, the amount of impurities in the steam

contributed by mechanical carry-over is the sum of the products of each impurity in the

boiler water multiplied by the moisture content of the steam.

Vaporous carry-over is the distillation of contaminants directly from the boiler water to

the steam. Unlike mechanical carry-over, vaporous carry-over is selective because the

particular constituent usually represents a different percentage of impurity in the steam

than it does in the boiler water.



Page 163 of 177


Total carry-over is the total of the mechanical and vaporous carry-over of all impurities.

Experience has shown that operation is satisfactory if the silica in the steam is

maintained below 25 ppb.

Vaporous carry-over is more difficult to alleviate than mechanical carry-over. The only

obvious way is to reduce chemical concentrations in the boiler water. Every kilogram of

chemicals added to the boiler water must be viewed as a potential source of difficulty.

Among the causes of moisture carry-over are high water level, high total solids content

of the boiler water, high alkalinity, and material. Operation of a boiler at loads in excess

of design rating will provide more cause for carry-over than operation within the design

rating. Sudden load changes will cause more difficulty than operation at steady loads.

D18.6.0.0 INTERNAL DEPOSITS

Internal deposits vary in both their physical and chemical character. They differ in

degree, all are barriers to heat transfer and prevent complete wetting of the tube

surfaces with water. The result is always elevated tube metal temperature.

At one extreme are the very hard and dense deposits, which are impervious to water

and are poor heat conductors. When these form in high heat input zones, the results

are tube failures from overheating.

The failures may be the result of rapid localized overheating where considerable

swelling and thinning of the tube wall has occurred. If the failure is of the long term

overheating, there may be little or no swelling and thinning of the tube.

At the other extreme are soft and porous deposits, which allow boiler water to seep to

the tube surface. The result is a concentration of boiler water constituents at the tube

surface. If the constituents are scale forming, more scale will form. If they consist of

caustic, under deposit corrosion will take place.



Page 164 of 177

TITLE: WATER TREATMENT D18.7.0.0 TREATMENT

Much of the art of feed-water treatment is devoted to the elimination of deposit forming

materials and the treatment of those minute quantities, which enter the boiler so as to

render them harmless. Pre-treatment equipment is used to eliminate, in so far as

possible, the deposit forming materials. Internal treatment handles the trace quantities,

which get past the pre-treatment equipment and also protects the boiler against

temporary upsets of the pre-treatment system, condenser leakage and contamination

from the condensate return system. In any case, internal boiler water treatment should

not be substituted for pre-treatment.

D18.8.0.0 PRE-TREATMENT

As operating pressures and percent make-up increase, it is imperative also to increase

the quality of the make-up water. As a guide for extended trouble free operation, the

feed-water quality limits indicated in Table-1 should be closely followed.

The type of pre-treatment necessary to obtain these limits depends almost entirely on

the quality and quantity of make-up water to the system. The type of pre-treatment may

include clarification and filtering, cold or hot lime soda, zerlite softening, demineralizers,

or evaporators.

D18.9.0.0 PRE-TREATMENT OF BOILER WATER TO PREVENT HARMFUL DEPOSITS

For boilers operating in the pressure range of 70kg/cm²(g) and above, more stringent

control is required to obtain the necessary feed-water quality. The make-up water

treatment should be of evaporative or demineralised quality. A demineralising plant has

the advantage of being able to produce high quality water without heat loss. However,

when raw water is particularly high in contaminants, there may be an economic

advantage in using an evaporator. The use of condensate polishing systems to ensure

minimum levels of both dissolved and suspended material in the cycle also provides the

additional advantage of reduced start-up time.



Page 165 of 177

TITLE: WATER TREATMENT D18.10.0.0 INTERNAL TREATMENT OF BOILER WATER

There are various methods for the internal treatment of boiler water. A blanket

recommendation of any one method is not realistic. The final decision as to the type of

treatment to be used in a particular boiler should be used on the raw water supply,

history of condenser leakage, the percent of make-up required, the nature of the

condensate returns, and other unique factors. A short summary of the recommended

internal water treatment methods is as follows:

D18.10.1.0 CONVENTIONAL TREATMENT

This type of treatment involves the addition of phosphate and caustic through the

chemical feed line to the steam drum. The caustic is added to the boiler water to

maintain the pH in the range of 10.2-11.2.

The primary purpose of phosphate addition to boiler water is to precipitate the hardness

constituents under the proper pH conditions. The calcium reacts with phosphate to

precipitate calcium phosphate as hydroxyapatite [calcium hydroxyapatite - Ca10 (PO4)6

(OH)2]. This is a flocculent precipitate tending to be less adherent to boiler surfaces

than simple tricalcium phosphate, which is precipitated below a pH of 10.2. Also,

caustic reacts with magnesium to form magnesium hydroxide or brucite [Brucite - Mg

(OH)2]. This precipitate is formed in preference to magnesium phosphate at a pH

above 10.5 and is considered, less adherent than magnesium phosphate.

At the higher pressures, comparatively low phosphate residuals must be maintained in

order to avoid appreciable phosphate hideout. Hideout is the term used to express the

phenomenon of the partial disappearance of phosphate in the boiler water upon

increase in load (drum pressure) and its reappearance upon load reduction. (A change

in phosphate concentration greater than 5 ppm as PO4 between high load and low load

is considered hideout). Phosphate hideout does not appear to be important below 100

bars and, even at this pressure, phosphate concentrations of 12 to 25ppm as PO4 can

be carried without appreciable hideout. When the pressure is increased to 150 bars,

the phosphate concentration must usually be decreased to 5 - 10 ppm as Na3PO4 to

avoid excessive hideout.



Page 166 of 177


D18.10.2.0 CO-ORDINATED PHOSPHATE TREATMENT

In this method of treatment, no free caustic is added to the boiler water. Figure 1

graphically shows the phosphate concentration versus the resulting pH when trisodium

phosphate is dissolved in water. Points on this Whirl-Purcell curve (mol ratio = 3.0)

indicate that all the phosphate exists as trisodium phosphate.

Recent laboratory tests show that the crystals, which precipitate from a solution of

trisodium phosphate at elevated temperatures, contains some disodium phosphate and

that the supernatant liquid contains sodium hydroxide. These same tests also indicated

that at mol ratios of 2.6 or less, free hydroxide did not form in the supernatant liquid. To

insure that no free caustic is present, we recommend a boiler water phosphate

concentration, which corresponds to a mol ratio of Na to PO4 of 2.6 as shown in Figure.

When using the regular commercial grades of chemicals, caution should be used in

calculating the weights to add to obtain the proper mol ratios since the phosphates are

in the form of Na3PO4 12H2O, Na2HPO4 7H2O. A mixture of 65 percent Na3PO4

12H2O and 35 percent Na2HPO4 7H2O corresponds to a mol ratio of Na to PO4 of 2.6.

In controlling the phosphate, should the pH be too low, it may be corrected by

increasing the ratio of trisodium to disodium phosphate. If the pH is high, this condition

may be corrected by decreasing this ratio. Figure 2 graphically shows the desired

phosphate concentration for a given operation pressure.

D18.10.3.0 VOLATILE TREATMENT WITH SUPPLEMENTAL PHOSPHATE This type of treatment is identical to the volatile treatment except that a small phosphate

residual is carried. How much phosphate that can be carried without excessive hideout

(greater than 5 ppm) change in phosphate concentration between high load and low

load varies somewhat between boiler units even at the same operating pressure. We,

therefore, recommended 3 - 10 ppm as PO4 as the range of concentrations that will not

produce excessive hideout. Phosphate is added to react with any residual hardness

that may escape the pre-treatment plant. The pH of the feed-water is usually

maintained at a value between 8.5 and 9.5 and the boiler water at a value between 9.0

and 10.0. As traces of impurities enter the cycle with the make up, the phosphate will be

precipitated producing free hydroxide.



Page 167 of 177


If supplemental phosphate treatment is used, it will be necessary to add di - or mono -

sodium phosphate to control the free hydroxide. Generally, the free hydroxide should

be maintained within 0 - 1 ppm.

D18.11.0.0 CONTROLS

For safe and efficient operation of boilers over 70 kg/cm² (g) operating pressure it is

necessary to continuously monitor the water quality. Early detection of any

contamination entering the cycle is essential so that immediate corrective action can be

taken before the boiler and its related equipment is damaged.

Electrical conductance, the reciprocal of resistance, affords rapid means of checking for

contamination in a water sample. Electrical conductance of a water sample is the

measure of its ability to conduct an electric current, and can be related to the ionisable

dissolved solids in the water. A single instrument will measure and record important

conductivities of the cycle water, from as many as twenty locations in the system. This

electrical conductivity signal can be used to actuate alarm systems or operate

equipment in the water system. The micromho (1x10-6 mho) is normally the unit of

measurement. For most salts in low concentrations, 2micromho equal 1ppm

concentration when corrected to 25°C.

Ammonia or amines used for pH control effect the conductivity. To obtain an accurate

indication of the solids, a cation ion exchanger is used to remove the volatile alkalizers

and convert the salts to their corresponding acids. The relationship is 7 micromho equal

1ppm concentration for most salts.

For boilers with operating pressures over 70kg/cm²(g), cation conductivity of the

condensate should normally run between 0.2 to 0.5 micromho. A reading above this

limit indicates the presence of some condenser leakage or contamination from some

other source. The source of the contamination should be investigated and remedied at

the first opportunity.

Dissolved oxygen should be monitored at the condensate pump discharge and the

deaerator outlet. Below 125kg/cm² (g) operating pressure where sulphite oxygen

scavenging and conventional or coordinated water treatment are used, the sulphite

chemical feed pumps are usually adjusted manually based upon the results of periodic

wet chemical analysis.



Page 168 of 177


Above 125 kg/cm² (g) operating pressure where hydrazine is used as an oxygen

scavenger and the volatile water treatment is used, the hydrazine pumps can be

controlled by either an analyser or recorder for oxygen hydrazine.

Feed-water pH is monitored at the economizer inlet and the condensate pump

discharge. Chemical injection pumps are usually adjusted manually to maintain the

proper pH for the conventional and coordinated phosphate water treatment systems.

Automated equipment is commercially available for the continuous on-stream analysis

of the critical constituents of the boiler water such as hardness phosphate, iron, copper

and silica. Most laboratory analytical procedures that depend on the development of a

colour and then measuring the intensity of that colour to indicate the concentration of

the constituent in the water sample can be put on an automatic basis.

D18.12.0.0 BLOWING DOWN

In many plants the amount and frequency of blowing down is determined from a

chemical analysis of the continuous blow-down from the boiler and the amount of blow-

down depending upon the quality of feed-water and the amount of steam generated. In

regular operation, economizer and furnace wall headers should never be blown down, in

the ordinary sense, while the unit is in active steam service. Valves on these pressure

parts are provided to serve only as drain valves and should be padlocked closed while

the boiler is in service.

The blow-down valves or any drain valve which permits hot water or steam under

pressure to flow into a relatively cold line should be opened slowly and gradually so that

at least one minute is allowed to open a 40 NB drain line from a 70kg/cm² (g) unit from

the time the hot medium starts coming through until the line is opened fully for the

complete blow. Proportionately more time is required for higher pressure and OD pipes.

If the water level in the gauge glass cannot be seen, by the person operating the blow-

down valves, an assistant should be so stationed that he can observe the level and

signal the completion of the desired amount of the blow-down.



Page 169 of 177


The disadvantages of intermittently blowing down, such as the resulting variations of

concentration and the inadvisability of blowing down, large quantities of water while the

boiler is operating at high duty, have brought about an increased use of the continuous

blow-down. This consists of a small size connection with a suitable regulating valve or

orifice, so located that blowing down can be accomplished without adversely affecting

boiler circulation. This method permits discharging a small quantity of water

continuously and allows easy adjustment of the quantity as called for by routine

chemical analysis.

TABLE-1 FEED WATER QUALITY LIMITS

Sl. No. Description Values

1. pH 8.5 - 9.2 * OR 9.3 - 9.5 **

2. Oxygen (ppm) 0.007 (Prefer 0)

3. Fe (ppm) 0.01

4. Cu (ppm) 0.005 Max.

5. SiO2 (ppm) 0.02 - 0.07

Note:

* With Copper alloys in feed-water heaters.

** With Carbon steel feed-water heaters.

RECOMMENDED BOILER WATER CONCENTRATIONS FOR CONVENTIONAL

TREATMENT

Characteristics Unit Value

Conductivity at 25oC Micro Siemens/cm 0.1

pH 9.0 – 10.0

Silica as SiO2 ppm 0.002

Phosphate as PO4 ppm 2



Page 170 of 177


CO-ORDINATED PHOSPHATE TREATMENT



Page 171 of 177


Co-ordinated Phosphate Treatment Drum Water Phosphate Limits

(Normally not used beyond 110 kg/cm2 pressure)



Page 172 of 177


Recommended Silica Concentration In Boiler Water At pH 9.5



Page 173 of 177

TITLE : LUBRICATION SCHEDULE

D19 - 0 - 0 - 0 LUBRICATION SCHEDULE



Page 174 of 177

TITLE: LUBRICATION SCHEDULE

Sl. No.

System / Equipment

Duration of Change / Top-up

Qty. in Litre

Trade Name of Lubricant Manufacturer

1

PA, SA and ID Fans: a. Bearings b. Coupling for

SA Fan PA

a. First oil change

after 500 running hours. Second oil change after every 2000 running hours. Every 5000 hours thereafter.

b. Complete grease

change after one year

3.6 1.75 Kg

a. Enklo-100 b. Servo Syst-100 c. Parthan Ep-5/4 d. Apreslube- 90/86 e. Meropa-5/4 (ISO VG-100) a. Servogem 2

a. BPCL b. Indian Oil c. HPCL d. Tide water e. Caltex a. Servogem 2

2

Coal Feeders a. Motor Bearing b. Pedestal Bearing for: i. Drive Sprocket Shaft ii. Trailing wheel shaft b. Gear Box c. Tension screws & connected nuts & bushes d. Drive Transm.

Roller Chain

a. Every 3 months b. Every 3 months c. Every 3 months d. Every 3 months e. Every 3 months

As reqd.

a. Energrease HTG 2 b. Temp 78 c. Spheerol BNS d. Thermotex EP 2

a. BP b. Mobil c. Castrol d. Caltex

4

Electric Motors - LT Motor : a. Bearings

The bearings should be cleaned and re-greased completely as regularly.

As reqd.

Lithium soap base Grease Grade-II for SA Fan. UNIREX-N3

Exxon Mobil

5

Electric Motors - HT Motors : a. Bearings

NA

NA NA NA



Page 175 of 177

TITLE: LUBRICATION SCHEDULE

6

Electrical Actuators for Dampers and Valves

NA NA NA NA

7

HP Dosing System:

Gear Reservoir of the Pump

Change every 500 hours of operation or every 3 months, whichever is earlier.

0.2 Litres

a. Servosystem 460

b. Enklo 460

a. Indian Oil

b. HPCL

8

Pneumatic Slide Gates for Bed, Cyclone Ash: a. Pneumatic

Actuator b. Gates

a. As and when

dismantled. b. Whenever

excessive operating torque is experienced.

As reqd.

a. Any moly based

grease. b. Any lithium

based grease.

Any std. Manufacturer.

9

Electrical Hoists:

Gears and Bearing

As and when dismantled or whenever excessive operating torque is experienced or once in a year.

As reqd.

Servogem 2

OCL



Page 176 of 177

TITLE : BOILER GA DRAWINGS AND P&I DIAGRAMS

E1 - 0 - 0 - 0 BOILER GA DRAWINGS AND P&I DIAGRAMS



Page 177 of 177

TITLE: BOILER GA DRAWINGS AND P&I DIAGRAMS

LIST OF DRAWINGS

Sr. No. Drawing Name Drawing No. Rev.

1. G.A. of Boiler PB-10969-0 F

2. Boiler Pressure Parts Assembly(FBB-35) PB-13961-0 A

3. Boiler Pressure Parts Assembly(FBB-36) PB-13963-0 0

4. P & ID of Water and Steam PB-10970 E

5. P & ID of Plant Steam system PB-10971-1 E

6. P & ID of Air / Flue gas PB-10972-1 D

7. P & ID of Fuel PB-10973-2 C

8. P & ID of Ash Handling System PB-10974-1 D

9. P & ID of HP Dosing PB-10975 C

10. P & ID of Hot Gas Generators Attached to HGG Manual

11. P & ID of Cooling water system PB-11919-2 C

Manual Part - II-MPL Project 23 07 2012.pdf

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