Unit Operating Procedures

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UNITOPERATING PROCEDURES

TABLE OF CONTENTS

DESCRIPTION PageINTRODUCTION 2

UNIT DESCRIPTION 2

PRE-OPERATION PROCEDURES 2

CLEAN-UP 2

CHEMICAL CLEANING 3

BLOWING STEAM LINES 3

SETTING SAFETY VALVES 3

COLD START-UP 3

PREPARATION FOR LIGHT OFF 3

INITIAL FIRING PRECAUTIONS 5

LIGHT OFF-COAL FIRING 8

NORMAL OPERATING-UNIT LOAD CHANGES-COAL FIRING 11DECREASING LOAD 11

INCREASING LOAD 12

NORMAL SHUTDOWN TO COLD 13

NORMAL SHUTDOWN TO HOT STANDBY 15

HOT RESTART 17

EMERGENCY PROCEDURES 18

REHEAT PROTECTION UPON LOSS OF LOAD 18TURBINE VALVE CLOSURE 18

TURBINE TRIP 18

POST TRIP PROCEDURE 18

TURBINE PROTECTION UPON LOSS OF LOAD 18

MASTER FUEL TRIP 19

LOW WATER LEVEL 20

HIGH WATER LEVEL 21

TUBE FAILURES 22

WATER WALL TUBES 22

ECONOMISER TUBES 22

SUPERHEATER AND REHEATER TUBES 22

ILLUSTRATIONS

AIR FLOW Vs LOAD CURVE


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INTRODUCTION

The procedures outlined in this section of the manual are intended to serve as a guide

during initial stages of operation. The procedures include precautions which should beobserved and the proper operating sequences of the unit, the fuel firing equipment andauxiliaries furnished by BHEL. Sequential procedures do not include detailed referenceto equipment furnished by others i. e. feed pumps, condensate pumps, turbine, etc.

Because the unit is only one part of the over all power station and since all equipmentmust operate in unison, specific procedures and detailed values cannot be included inthis manual. As operating experience is gained and controls are fine tuned by the units

characteristics and actual operating requirements will become evident to the operator.

Reference should be made to the control vendors instructions for further operatingdetails.

Reference should be made to the manufacturer's instructions regarding operational andpre-operational procedures for their equipment.

UNIT DESCRIPTION

The unit is a Controlled Circulation plus Radiant Reheat (type CC + RR) boiler. Firingequipment consists of five elevations (20) of remotely controllable High Energy Arcigniters, five elevations (20) of retractable air or steam atomizing oil guns and tenelevations (40) of pulverised coal nozzles. The ten elevations of pulverised coal nozzlesare supplied with coal from ten number type 1003 XRP pulverizers. Completedescriptions of the equipment provided can be found elsewhere in this manual.

Control equipment provided consists of a Furnace Safeguard Supervisory System,Scanner Air Control System and a Secondary Air Control System.

Major auxiliary equipment provided consists of Pulveriser Feeders and Scanner AirFans and miscellaneous valves.

Three Hayward Tyler boiler circulating pumps are provided to insure proper circulation

of water in the furnace wall circuits.

Coal is used as load carrying fuel for which startup procedure is given below:

PRE-OPERATIOINAL PROCEDURES

Clean-Up


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Chemical Cleaning

Specific procedures for boiling out and acid cleaning are included elsewhere in this

manual Firing and circulating pump operating procedures as outlined under Cold Startup, Lighting off" should be used as a guide when operating the fuel firing equipment.

Blowing Steam Lines

Prior to starting up a new unit or following major pressure parts repairs on an older unit,the main steam lines and the reheater steam lines should be blown out to remove scaleand foreign matter thereby preventing damage to the turbine. This should be done after

acid cleaning and prior to setting boiler and superheater safety valves. Considerationshould be given to setting the reheater safety valves before removing the temporaryblow out piping.

Refer to "Steam Line Blowing Procedures" elsewhere in this manual for recommendedoperating procedures and precautions.

Setting Safety Valves

Setting of the Safety valves on the drum and superheater should be done prior toturbine rolling. Refer to the safety valve manufacturers instructions for settingprocedures. A conservative firing rate should be maintained, limiting the furnace exitgas temperature to a minimum of 540DC. If the reheater safety valves were not setduring the steam line blowing procedure, they may be set while the turbine is carrying alight load, by closing down on the intercept valves until a reheat steam pressure isreached high enough to lift the reheat safeties. (Consult the turbine manufacturer's

instructions for allowable procedures). Popping pressure and blowdowns should beadjusted to conform to design values.

COLD START-UPPreparations for Lighting offIt is assumed that at this time the following preparatory work has been completed:

1. The unit has been chemically cleaned, that the steam lines have been blown, that

the safety valves have been set and that the unit has been filled to slightly abovethe normal operating level with properly treated feedwater.

2. All control systems have been checked out and are available for service.

NOTE : Check all safety interlock systems prior to start up to insure proper


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a. Oil guns inserted and properly coupled. (Check gaskets between unions.)

b. All oil gun and igniter quick disconnect couplings properly assembled.

c. All fuel manual valves open.

d. All fuel control valves closed.

5. The pulverizers and feeders have been checked out and are available for service.Recheck items such as:

a. Pulverizer discharge valves open.

b. Hot air gates closed; hot air control dampers closed.

c. Cold air gates open; cold air control dampers open approximately 5%,

d. Bunker outlet valves open; coal available to feeders.

e. Pulverizer and feeder seal air valves open.

f. All classifier vane settings identical.

6. The windboxes have been checked for proper damper positioning, tilts at

horizontal, etc.

7. The feedwater system, instrumentation and equipment, has been checked out andis available for operation. It is recommended that during startups the feedwater becontrolled remote-manually, until a continuous flow is established. See LightingOff. To avoid the possibility of oxygen corrosion in the boiler, the USB of un-deaerated feedwater (temperature less than 100oC) is not recommended. Refer tothe "Water Treatment" instructions elsewhere in this manual.

8. The boiler circulating pumps have been checked out that they have been properlyfilled and vented and that all pump instrumentation is available for service. It isimperative that the pump differential pressure switches are in service and that theproper trip settings have been made.

9. All air handling equipment has been checked out and is available for service. Allair and gas duct dampers should be in the start up position. (Refer to Note and

Caution below.)

a. I. D. Fan outlet shut off dampers open, inlet control dampers closed.

b. F. D. Fan outlet shut off dampers and blade pitch open. (F. D. Fan blade pitchshould be closed before the fan is started-see Note 1.)

c Primary air fan outletshut off dampers and blade pitch closed


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fans, both Air Preheaters, and both Primary Air Fans in service. If theunit started with only one I. D., F. D. and P. A. fan and one air heater inservice, the above damper positions apply to the equipment to be

started. Dampers associated with the idle equipment should be closed.

CAUTION: The I. D. Fans may be capable of developing drafts in excess of thefurnace design pressure. Therefore, the operator must take care toestablish and maintain an air flow path through the unit, prior to startingan I. D. Fan and prior to opening the I. D. Fan inlet control dampers, byinsuring that other dampers in the system are in the start up positionsindicated above.

I. D. Fan inlet control dampers must be kept closed until after the fan isstarted. This procedure minimizes the possibility of developing excessivenegative pressure in the unit during the starting procedure.

The operator must take care to maintain the furnace draft within satelimits at all times. He must be especially careful when draft and air flowcontrols are in the Manual " mode. He must be alert at all times for

possible malfunctions of automatic control equipment resulting inabnormal excursions in furnace pressure, either negative or positive.

10. Check that the Air Heaters have been prepared for service, that an adequatemeans of extinguishing air heater fires is available and ready for use. Refer to AirPreheater instructions for details.

11. The soot blowing equipment has been checked for proper operation and the

system is in the start up conditions. (All blowers retracted, main steam supply valveopen.)

12. All Desuperheater Spray Water Control Valves are closed.

13. All boiler Superheater and Reheater drain and vent valves are in the start upposition.

CAUTION : Prevent possible water damage to the turbine by using extreme careto eliminate all water from the main steam line(s), cold and hot reheatlines and superheater and reheater elements and headers before theturbine is rolled. Refer to the turbine manufacturer's instructions.

14. The furnace gas temperature probe is in working order and available for service.


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of explosive mixtures in the event of poor or delayed ignition after fuel is introducedto the furnace.

2, High excess air through the air heater. This minimizes the dilution of combustionair by inerts, carried over by the air heater rotor.

Air flow should be increased when the boiler reaches a load where additional air isrequired to maintain the design operating excess air. Refer to "Air Regulation" in thesection "Tilting Tangential Firing System".

1. Start two boiler circulating pumps in accordance with pump operating instructions.

The pump starting recommendations anticipate a normal rate of hotter watertemperature rise of about 110oC per hour (i e. 27oC in 15 minutes). Quick boilerstarts can create temperature changes approaching 83

oC in 15 minutes. Pumps

should not be started during intervals of rapid boiler water temperature change.

NOTE: It may be preferable to start only two pumps in order to minimize flashingin the downcomers (and the consequent piping vibration) when the boilerwater is in the range of 95 to 125oC, The third pump should be started

before the boiler drum pressure reaches 7 kgjcm2 to minimize pumpstarting temperature transients.

2. Start both air heaters. (Refer to Air Preheater instructions "Placing Air Heaters inService".)

3. Start scanner air fan.

4. Start two I. D. Fans (see "Caution" under Item 9, "Preparation for Lighting Off")5. Start two P. A. Fans (see Note)

NOTE: Air flow must be maintained through the pulverizer whenever the unit isbeing fired. Therefore P. A. fans must be in service. Open the P. A. Fansoutlet shutoff dampers of the selected fan. Bring the primary hot air ductpressure up to the set point by "Manually" opening the P. A. Fan inletcontrol damper. Then transfer to "Auto" control. When the pulverizers are

out of service, their discharge valves must be fully open and the cold airinlet control dampers must be open to a minimum position. The dischargevalves are closed for pulverizer maintenance or when the pulverizers areidle, full of coal and other pulverizers are being started after a unit trip.See "Emergency Procedures, Master Fuel Trip".


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modulate the auxiliary air dampers to maintain a programmed set point differentialbetween the windbox and furnace. Check that all other purge permissives aresatisfied.

10. Initiate a furnace purge. Upon completion of the purge cycle, check that all firingprerequisites are satisfied.

11. Place the gas temperature probe in service.

12. Initiate a light off sequence of the lower elevation of igniters and warm-up oil guns.Refer to the "Furnace Safeguard Supervisory System", "Igniter" and "Retractable

Oil Gun" instructions for details.

13. During the warming period the economizer recircutating line valves are open. Blowdown the unit as required to maintain the water level in sight in the gauge glass.

14. The firing rate should be controlled to keep the furnace exit gas temperaturebelow 540oC until the HP - LP Bypass is cut in. When the drum pressureincreases, position the superheater and reheater drains and vents and drum ventsin accordance with step 21.

During startups, lighting off is done with the lower igniters and warm up oil guns.Warming up can be accomplished with either the warmup oil guns or pulverized coalfiring. In either case, the required firing rate must permit operation of an entire elevationof fuel nozzles without exceeding the furnace exit gas temperature limitation asdescribed in the following paragraph.

NOTE: To minimize the possibility of adverse visible stack emission, it if desirable

to use the igniters and warm up oil guns to at feast 35 kg/cm2

(g) drumpressure and 175oC secondary air temperature before firing pulverizedcoal or heavy oil.

During all start-ups the firing rate should be controlled to keep the maximum furnaceexit gas temperature below 540C (as measured by the furnace outlet gas temperatureprobe) until the HP- LP Bypass is cut in. After rolling the turbine, the steam temperatureand pressure rise at the turbine throttle should at all times be in accordance with the

limits prescribed by the turbine manufacturer.

NOTE: It is recommended that during initial start of a new unit a relatively slowrate of pressure increase be followed, in order to allow sufficient time forchecking expansion movements and to permit the operators to becomefamiliar with the characteristics of the unit and its auxiliaries. Once these


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Opening the backpass drain valves (see Note), preferably in steps, will cause areduction in the unit pressure. An increase in firing rate to maintain pressure will providea subsequent increase in the superheater outlet steam temperature. EXERCISE CARE

NOT TO EXCEED THE FURNACE EXIT GAS TEMPERATURE LIMIT OF 540o C,Modulating the steam pressure and temperature by this method permits the unit toattain the highest possible superheater outlet temperature, approaching the turbinemetal temperature on a hot restart or 55o of superheat during a cold start.

NOTE: Drain valves should be either open or fully closed, not throttled

CAUTION: All backpass drain valves must be closed immediately after the unit is

synchronized.

Lighting off-Coal Firing

15. Increase the firing rare as required to raise pressure. Take care not to exceed thefurnace exit gas temperature limit to 540o C until the HP-LP Bypass is cut in. Whenready to fire coal, the pulverizer serving a lower elevation of coal nozzles should beprepared for operation and started in accordance with steps 24 through 27.

Adjacent warm-up oil guns supply the required ignition energy. The feeder ratingshould be controlled to keep the furnace exit gas temperature from exceeding540oC until the HP-LP Bypass is cut in.

16. While the unit is heating up frequent checks should be made of the boilerexpansion movements. Special attention should be given to expansion of the lowerpart of the boiler (furnace inlet drums, pump suction manifold etc.) relative tobuilding steel. Expansion movement should be recorded for comparison with future

Start-ups. Refer to the Expansion Movement Diagrams, in the "Pressure Parts"section of the manual.

17. Maintain drum water level at normal and check boiler water concentrations andconstituents as frequently as required to maintain proper boiler water conditions.

18. When continuous feed water flow is established the economizer recirculating linevalves may be closed.

19. Before raising a vacuum in the condenser make sure that all reheater vents ordrains that are open to atmosphere are closed. Leave drains or vents connected tothe condensate open until the turbine is carrying a light load.

20. Start the third boiler circulating pump before the drum pressure reaches 7 kg/cm2to minimize the temperature transients experienced by the pump casting. Two


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21. As drum pressure increases, progressively throttle the superheater main steamline vent (Start Up Vent) and other start-up vents and drains used (main steam linedrain, turbine drains, etc.). Sufficient steam flow must be maintained at all times to

assure clearing the superheater elements of condensate. Increase the firing rateas necessary, without exceeding the furnace exit gas temperature limitation. Donot close start-up drains completely until steam flow through the turbine isestablished. The superheater backpass lower front inlet header and backpass rearinlet header drains should normally be closed immediately after steam is admittedto the turbine.

22. Start rolling the turbine as soon as the minimum permissible start-up pressure and

temperature, specified by the turbine manufacturer are reached. Refer to turbinemanufacturer's instructions.

23. When bringing the turbine up to speed, the firing rate should be controlled, toprevent the furnace exit gas temperature from exceeding 5WC until the HP-LPBypass is cut in. When the turbine is up to speed, it may be synchronized. At thispoint the gas temperature probe may be withdrawn and the firing rate increased asrequired. In no case should the firing rate exceed that which is necessary to satisfy

steam demand.

NOTE: If the unit is put on the line before design operating pressure is reached,further increase of firing rate should be in accordance with a gradual rateof pressure increase consistent with increasing load. Do not allow steamtemperature to exceed the values shown in drg. No. 4Q-BPE-1532

CAUTION: Operators should be alert to detect the symptoms of water carryover

from the boiler and introduction of water into the turbine such as:

a. A sudden unexplained drop in steam temperature in either the main steam or hotreheat line.

b. Vibration in the steam piping resulting from water hammer.

c. Abnormal vibration and differential expansion readings from the turbine supervisoryinstrumentation.

Operators must be prepared to take actions necessary to prevent turbine damage upondetection of water introduction. Refer to turbine manufacturer's instruction for specificactions to be taken.

24 If coal was not fired previously (see Note) the pulverizer serving the lowest


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Supervisory System instructions. The coal fuel-air dampers should remain closeduntil ignition is established. Refer to "Air Flow Control and Distribution" in theSection "Tangential Firing System". Check to see that the nozzle tilts ate

horizontal. Place 3 second P. A. Fan in service if not done previously.

26. Start the pulverizer (see Note), Open the hot air shut-off gate and bring thepulverizer up to the required operation temperature without coal. Place pulverizerair flow and temperature control on Auto. When ready to fire coal, start the feederat minimum rating (Manual control). Ignition of the pulverized coal should takeplace immediately. When the pulverizer is proven in service the fuel air dampersshould open automatically. Maintain the fuel feed at a minimum consistent with

stable ignition. Watch the fires.

NOTE: If the unit start-up follows a Master Fuel Trip the pulverizer may not beempty. It must be operated to cleat it of excess coal before starting thefeeder. During this procedure the pulverizer valves of all other idlepulverizers must be closed in order to prevent blowing hot furnace gasesback into the idle pulverizers and coal piping. (See "EmergencyProcedures".) When most of the coat has been removed from the

pulverizer, the feeder can be started at minimum speed and then adjustedto a speed selected to give a stable flame or, as required to meet unit loadrequirements. Do not admit hot air to the pulverizer until the feeder isstarted. Be sure that the ignition energy is established before starting thepulverizer.

If the ignition does not take place within 5 seconds after coal appears at the coalnozzles, stop the feeder. Determine the cause of ignition failure before attempting

to restart the feeder.

27. Maintain proper coal / air temperature leaving the pulverizers. Regulate the hotand cold air dampers to hold between 70oC and 80o C for Bituminous (Highvolatile) coal at the pulverizer outlet. At no time should this temperature exceed93o C. If it should exceed 93oC, the hot air gate must be closed.

NOTE: Pulverizer start up will cause a sudden and sharp increase of steampressure. This will level out rapidly as load is placed on the turbine.

Check the pulverizer oil temperature and turn on the water to the oil cooler whenthe temperature approaches 65oC. The oil temperature should not exceed 70oC atany time.

28. Place the second pulverizer (supplying the adjacent (*) elevation of coal nozzles)


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in service with feeder ratings on each associated pulverizer greater than50%.

29. The Furnace Safeguard Supervisory System and Secondary Air Damper Controlsshould close the auxiliary air dampers serving compartments adjacent to coalnozzles which are out of service when the boiler reaches 30% of full load andincreases the windbox to furnace differential pressure to approximately 100 mm.w.g.

30. It is essential that the air flow to the furnace is sufficient for the firing rate at alltimes. Automatic control equipment is normally arranged to maintain such a

balanced condition. The O2 measuring devices, which are often tied in with the airflow control, should be checked periodically to assure continuous and dependableoperation.

31. Place additional pulverizers in service as the unit loading demands. The pulverizerserving the lowest available nozzle elevation not already in service should bestarted when the feeders in service reach approximately 80% rating. As eachpulverizer is placed in service the required associated ignition energy must be

available. When the unit firing conditions are stabilized all warm up oil guns andigniters may be taken out of service. (Refer to the Furnace safeguard SupervisorySystem instructions.)

32. Place the steam temperature controls and combustion controls on "Auto" whenfiring conditions are stable and the temperature and pressure control set pointshave been reached. Refer to the control manufacturer's instructions for specificprocedures

33. Adjust the feedwater supply to the boiler as necessary to maintain normal waterlevel. Feedwater control should be placed on automatic as soon as possible andpracticable after continuous feedwater flow is established.

34. Overfire air should not be utilized (for NOx control) below 50% load. The effectivestarting load must be determined during initial unit operation. Refer to operatingrecommendations in the "Tilting Tangential Firing System".

NORMAL OPERATION - UNIT LOAD CHANGES (Coal Firing)

During normal operation, with the unit on the line changes in pulverizer loading and/orthe number of pulverizers in service may be required to accommodate unit loadchanges. A wide range of load control can be achieved with the pulverizers onautomatic.


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6. The auxiliary supporting fuel (associated Igniters and warm up guns) may be takenout of service when furnace conditions have stabilized and at least two pulverizersare in service, each with a feeder rating of at least 50%.

7. Place additional pulverizers in service in the same manner, as required by loadincrease demand.

NORMAL SHUTDOWN TO COLD

The following procedures for normal shutdown are based on the assumption that theunit is operating at full load on automatic control and that it is the intention to reduce the

pressure to zero and cool the boiler completely.

1. Gradually reduce load on the unit; reduce the firing rate in line with the decreasingsteam flow. Allow the pressure to drop with the reduction in load to acceleratecooling. Reduce the steam temperature at the rate prescribed by the turbinemanufacturer.

Steam temperature control, combustion control and feedwater control may be lefton automatic until the point is reached where better control can be obtained onmanual.

CAUTION: Care must be exercised to prevent water from entering the mainsteam line(s), the hot reheat line(s) and the cold reheat line(s) to theturbine from any source during and after the shutdown process. This isto prevent possible water damage to the turbine during a subsequentrestart. Possible sources of water are:

a. Overflow from the drum into the superheater as a result of highwater level.

b. Water entering the superheater or reheater through thedesuperheaters due to open desuperheater control valves orpossible valve leakage with the feed pumps running,

2. When the feeder rating on all pulverizers is reduced to 40% of maximum, place the

pulverizer supplying the upper coal elevation on manual control. Gradually reducethe feeder rating. When minimum rating is reached, close the hot air shut off gate.Stop the feeder when the coal-air temperature has dropped to approximately 60oC.It is advisable to close the coal shut off gate above the feeder and run the spoutand feeders empty before stopping the feeder. Keep the pulverizer running forabout 2 minutes 01 until it is completely empty and then stop the pulverizer Refer


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service in the same manner. *When down to 2 pulverizers the adjacent warm up oilguns must be placed in service, prior to reducing the feeder rating of eitherpulverizer to below 50% maximum.

*NOTE: It is recommended that the above consecutive elevation shut downsequence be followed. Firing coal at separated coal nozzle elevationswithout auxiliary supporting fuel is not permitted.

5. Discontinue admission of overfire air when the unit load has dropped below thepredetermined effective starting load. Keep the overfire air dampers slightlycracked open to prevent the nozzles from overheating.

6. Operate all sootblowers. Refer to manufacturer's instructions.

7. Reduce the air flow in line with fuel reduction until 30% of maximum air flow isreached. Do not reduce the air flow below this rating until all fires are out and theunit is off the line. (See Figure 3.) To avoid firing instability during this period ofhigh relative air flow, the auxiliary air dampers at all elevations should open andreduce the wind box to furnace differential pressure to its lower setting.

8. Check the expansion movement of the unit as load is being reduced.

9. After the last pulverizer has been shut down, remove the warmup oil guns and theigniters from service. Shut off the cooling water to the pulverizers. All fires shouldbe removed when the unit is off the line.

10. Immediately after closing the turbine stop valves, open wide the superheater outletvents and drains and all reheater vents and drains. Open other drains in the

superheater system as required for further pressure reduction. Open steam lineand turbine drains as described by the turbine manufacturer.

11. Open the economizer recirculating line valves. Close desuperheater isolatingvalves.

12. If during the shut down period, it is not necessary to enter the unit sooner, a slowrate of pressure and temperature decay may be desirable. This can be

accomplished as follows :

a. Purge the unit by running the induced draft and forced draft fans, for at leastfive minutes (at 30% air flow) after the fires are extinguished.

b. Reduce the air flow through the unit to a minimum. Keep the fans and airheaters* in service until the unit has cooled to the desired temperature.


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a. Purge the unit by running the induced draft and forced draft for at least fiveminutes (at a minimum of 30% air flow) after the fires are extinguished.

b. Continue running the fans to cool the unit at the desired rate. The air heatersmay be shut down when the gas entering temperature has dropped below205oC (Refer to the Air Preheater instructions)

NOTE: With the air heaters stopped and the fans running, deposits of fly ash mayaccumulate in the air heater resulting unbalance of the rotors.

c. Keep one boiler circulating pump in service to increase recirculation. Maintainthe water level near normal in the gage. Shut down the pump when the boiler

water temperature is reduced to the desired level.

14. Open the drum vents when the unit pressure has been reduced to 2 kg/cm2g.

15. If the boiler is laid up wet, refer to "Lay-Up Procedures".

16. If the boiler will be emptied, the boiler water temperature should be reduced to atleast 95oC before draining

NORMAL SHUTDOWN TO HOT STANDBY

It is assumed that the boiler will be shut down for a relatively short period of time andexisting pressure and temperature conditions will be substantially maintained. Aprocedure similar to that for normal shutdown should be followed except:

1. Do not reduce drum pressure in line with unit load reduction. The rate or pressuredrop should be much smaller than the rate followed during normal shutdown.When the desired pressure at which the boiler is to be held is reached - after theturbine is off the line-the boiler may be bottled up by closing all superheater drainsand vents. Reheater drains and vents are kept open.

CAUTION: Care must be exercised to prevent water from entering the main steamline(s), the hot reheat line(s) and the cold reheat line(s), to the turbinefrom any source during and after the shutdown process. This is toprevent possible water damage to the turbine during a subsequent

restart. Possible sources of water are:a. Overflow from the drum into the superheater as a result of high water level.

b. Water entering the superheater or reheater through the desuperheaters due tothe open desuperheater control valves or possible valve leakage with the feedpumps running.


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baiter water. Opening the pump bypass valves wilt provide a moderaterate of cooling of the pump case. A pump should not be started if thepump casing temperature exceeds the down-comer temperature by

more than 55oC. If load and pressure will subsequently be increased it ispreferable to delay the starting of the pump until the downcomertemperature has increased to within 28oC or the pump casingtemperature to minimize the effects of temperature transients.

2. It is not necessary to close the feeder inlet gates and to run the spouts and feedersempty. As each pulverizer is taken out of service, close the hot air shut off gate.Stop the feeder when the coal-air temperature drops to 50oC. Run the pulverizer

until empty and stop the pulverizer.

3. One boiler circulating pump should be kept in operation to insure adequate boilerwater circulation which will prevent possible local overheating due to hot slagdeposits,

4. It is recommended that, after all fires are extinguished (see caution below) the I. D.and F. D. Fans and air heaters be kept running until the air heater gas inlettemperature has dropped to below 205oC. (See warning below.) Close all gasduct, secondary air duct and windbox dampers after the air heaters and fans areshut down.

CAUTION: If it is known or suspected that combustible deposits are present in theair heater elements, the air heater gas temperature must be reduced to205oC before shutting down the F. D. Fans, I, D. Fans, and air heaters.The air heaters must be thoroughly cleaned to remove anycombustible products before they are shut down.

WARNING: If it is elected to shut down the fans with the airheater gas inlettemperature above 205C, the airheater MUST be kept rotatingHowever, running an airheater with the gas inlet temperature above205oC and no air flow through it will result in seal damage andsubsequent excessive leakage during operation. (Refer to airheaterinstructions) The decision to bottle up the unit above 205oC must bemade with this in mind.

5. All boiler circulating pumps may be shut down after the unit has been bottled up.However, if a hot restart is anticipated at least one pump should remain in serviceto provide more effective warm up circulation for the idle pumps. The ideal pumpsmay be placed on "hot standby", that is; suction and discharge valves open. Referto the "Pump Operating Procedures" for complete pump standby requirements.


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NOTE: The operator should observe the gage glass periodically so that he isalways aware of the actual drum level and can take the appropriate actionto re-establish water level when the unit is being restarted.

HOT RESTART

Assuming the boiler has been down for a comparatively short period of time andconsiderable drum pressure was maintained, the following procedures should be usedin restarting the unit.

1. Make a general inspection of the boiler and check the points as mentioned undernormal start-up.

2. One boiler circulating pump should still be in service.

3. If the airheaters and fans were shutdown at reduced temperature (see Step 4,Normal Shutdown to Hot Standby), start the air heaters and fans as outlined under"Cold Startup-lighting Off", If the unit was bottled up hot, with the air heaters stillrunning, start the fans in the normal sequence.

4. Open wide all superheater drains to allow complete draining of superheaterheaders and/ or elements. After draining close all drains, except the SuperheaterBackpass Front Inlet Header and Backpass Rear Inlet Header drains and the start-up drains (Main Steam Line Vent and drains). Keep the Backpass Header drainsopen. Reheat drains and vents are open. Open the economizer recirculating lineand the desuperheater isolating valves. (Desuperheater control valves must beclosed.)

CAUTION: Prevent possible water damage to the turbine by using extreme care toeliminate all water from the main steam line(s), cold and hot reheatlines and superheater and reheater elements and headers before theturbine is rolled. Refer to the turbine manufacturer's instructions.

5. Initiate a furnace purge and normal light off sequence of the igniters and warm upoil guns.

6. Close all reheater vents and atmospheric drains before pulling a vacuum in the

condenser. Reheater condenser drains may be left open until the turbine is underlight load.

7. When steam is admitted to the turbine for rolling it is desirable to have a minimumsteam/turbine metal temperature differential. This can be achieved by firing at amaximum rate within the furnace exit gas temperature limitation of 540oC In order


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a. A sudden unexplained drop in the steam temperature in either themain steam or hot reheat lines.

b. Vibration in the steam piping resulting from water hammer.

c. Abnormal vibration and differential expansion readings from theturbine supervisory instrumentation.

Operators must be prepared to take the actions necessary to preventturbine damage upon detection of water introduction. Refer to theturbine manufacturer's instructions for specific actions to be taken.

MASTER FUEL TRIP

Under conditions requiring a master fuel trip through normal interlocks or operatorsaction (manual trip); all fuel should be tripped instantaneously. If coal was being fired,the pulverizers should be tripped immediately. Tripping the pulverizers will automaticallytrip the feeders and close the hot air shut off gates. (Refer to emergency shutdownprocedures in section "Pulverizers".) If oil was being fired, the trip valves and individualnozzle shut off valves should be closed immediately.

The following steps should be taken immediately following an emergency fuel trip.

1. Maintain the unit air flow at pre-trip value for at least 5 minutes to purge thesystem. If a hot restart is anticipated the air flow (30% of full load air low) duringthe 5 minute purge. At least two boiler circulating pumps should remain in serviceto maintain uniform temperatures throughout the boiler circulation system and tofacilitate lighting off. In no case should all the pumps be stopped (refer to the"Pump Operating Procedures").

2. IF oil guns were in service when the fuel trip occurred, check to insure that allindividual nozzle shut off valves are closed. Oil guns should be retracted (SeeNote 1), removed, cleaned (See Note 2) and reinstalled, to be ready for a restart ofthe unit

NOTE: 1. Refer to the Furnace Safeguard Supervisory System instructions foremergency oil gun shutdown sequencing.

2. If immediate restart of the unit is anticipated, oil guns do not requirecleaning.

3. If during a fuel trip all auxiliaries are lost, refer to the Boiler Circulating PumpOperating Procedures" for handling of the low pressure cooling water. Flow mustbe maintained.


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A. Close the pulverizer discharge valves on all other idle pulverizers that containcoal. This will prevent hot furnace gases from being carried back into thesepulverizers in the event of a furnace pressure rise when a mill is started.

B. Establish the required ignition energy for the pulverizer to be started (See Note1.)

C. Start the pulverizer and allow it to clear itself of coal (See Note 2).

1) If the pulverizer will be retained in service, start its feeder when thepulverizer amps begin to fall off. When the feeder is started, open the hot air

shut off gate and bring the pulverizer upto normal operating temperature.(See Note 3).

2) If the pulverizer will no! be retained in service, stop the pulverizer after it iscompletely cleared of coat. The pulverizer discharge valves should remainopen to allow a flow of cooling air through the empty pulverizer.

D. An emergency trip subjects residual fuel in the pulverizers to conditions whichmay cause spontaneous combustion. If the unit cannot be re-fired within a

reasonable time (45 minutes) to permit clearing the pulverizers, then thepulverizers should be cooled to ambient and manually unloaded or at minimum,they should be isolated and ail doors should be removed to prevent gases fromentering the furnace.

NOTE: 1. Refer to Unit Cold Startup procedures and Furnace SafeguardSupervisory System instructions for Ignition Energy requirements andpermissives.

2. If due to load conditions and/or requirements of the Furnace SafeguardSupervisory System, it is impossible to establish pulverizer ignitionpermissive for all pulverizers and chat them of coal the dischargevalves of all idle pulverizers (including those still containing coal)should be opened to allow a flow of cooling air through the pulverizer.The discharge valves should remain open until ready to unload and I orrestart a pulverizer.

Each time an additional pulverizer is placed in service or unloaded, anyidle pulverizer containing coal should again be temporarily isolated,see Item A.

3. Following a pulverizer trip under load, the pulverizer should beoperated with cold air only, until its feeder is started.


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water level can be restored immediately without damaging the boiler. In the absence ofsuch a decision:

1. Trip all fuel immediately.

2. Shut of all steam being discharged from the unit, (trip turbine, steam drivenauxiliaries, etc.)

3. Leave the boiler circulating pumps in service as long as they are operatingnormally and do not loose suction due to the low water level.

4. If feedwater has become available and the boiler circulating pump(s) are stillrunning, gradually re-establish the level in the drum.

5. If no boiler circulating pumps can be maintained in service, do not admit feedwaterto the unit.

6. Maintain ahigh air flow at first to hasten the cooling process.

7. If pressure parts damage is suspected, reduce the steam pressure gradually byopening the superheater start up drains. Open the drum vents when the pressuredrops below 2 kg/cm2g as the boiler cools reduce the air flow. Shut down the airheaters and fans as soon as the unit is cool enough for a man to enter. Drain theboiler when the drum metal temperature is 93oC following normal drainingprocedures. Determine the cause of low water and examine the boiler for theeffects of possible overheating such as leaks and distortion of pressure parts.

8. Repair any leaks, etc.

9. Hydrostatically test the boiler at working pressure before putting the unit back inservice.

HIGH WATER LEVEL

Abnormally high water level should be avoided as it may lead to carryover and evenpriming. If the water level rises above the recommended normal operating range

proceed as follows:

1. Reduce the water level immediately by opening the intermittent blowdown valves.

2. Reduce the steaming rate, if necessary, and place feedwater control on Manual.


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4. Investigate the condition of the drum internals as soon as an opportunity Isafforded.

TUBE FAILURES

Water Wall Tubes

In the event of failure of one or more water carrying tubes in a controlled circulationboiler, the best method for shutting down the unit will be dictated by the size of thefailure, the ability to maintain normal water level and the demands for the service of theunit.

The following instructions regarding tube failures are of a general nature. It must beunderstood that conditions may arise which will require exercise of judgment by theoperators.

In case of a leak or tube failure, which does not involve a serious drain on the feedwatersupply, the water level should be maintained and the unit is taken out of service in anormal manner. Refer to Normal Shutdown Procedures.

If the tube failure results in a loss of water so great that the water level cannot bemaintained with the feedwater supply available, use the method outlined below:

1. Trip all fuel.

2. Shut down the last boiler circulating pump just before the water level goes out ofsight after the fuel is tripped.

3. Shut off feedwater to the boiler,

4. Maintain only enough air flow to carry the escaping steam up the stack.

5. Leave fans and airheaters in service until pressure is off the unit.

6. After the unit has cooled enough to permit a man to enter it, make a thoroughinspection of pressure parts for any indication of damage resulting from loss ofwater level. After the necessary repairs have been made, apply a hydrostatic testand obtain the approval of the proper authority before putting the unit back inservice.

Economizer Tubes

An economizer tube leak can be detected by sound and/or increased make up waterrequirements. The leak should be investigated at the earliest possible time and the unitshut down in a normal manner. Water leaks in the economizer can cause considerable


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Any decision to continue with known leaks should be made with this in mind.

A major superheater or reheater tube failure may require an emergency unit shutdown.

The operator must use his judgment to assess the seriousness of the failure and itsconsequences and then decide what type of shutdown is required.


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BOILER PARAMETERS( CONSTANT PRESSURE OPERATION)

LOAD

DESCRIPTION HP Heater In HPHS

Out

100%

BMCR**

89.41%

BMCR

500 MW*

71.3%

BMCR

400MW*

53.9%

BMCR

300 MW*

MAX.

HEAT

INPUT

MAIN STEAM

Steam flow at SH Outlet t / h 1675.00 1498.53 1198.93 909.27 1447.22

Pressure at SH Outlet kg / cm2 (g) 178.0 176.2 173.8 171.6 175.7

Temperature at SH Outlet o C 540.0 540.0 540.0 540.0 540.0

REHEAT STEAM

Steam flow at RH Outlet t / h 1397.4 1335.15 1078.04 825.78 1445.5

Pressure at HPT Outlet / RH Inlet kg / cm2 (g) 44.99 42.99 34.70 26.52 46.18

Temperature at HPT Outlet / RH Inlet o C 338.5 337.4 329.5 321.7 352.3

Pressure drop - RH kg / cm2 2.1 2.01 1.62 1.24 2.17

Pressure at RH Outlet / IPT In let kg / cm2 (g) 42.89 40.98 33.08 25.28 44.01

Temperature at RH Outlet / IPT Inlet o C 540.0 540.0 540.0 540.0 540.0

FEED WATER

Feed Water Temperature o C255.2 253.4 242.7 229.6 171.5

REMARKS: 1) Boiler Parameters are based on Annexure-IV to MoM dated 7/7/2003 except for 60%BMCR

2) ** Maximum capacity Point

3) * Performance Guarantee points


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BOILER PARAMETERS( CONSTANT PRESSURE OPERATION)

LOAD

DESCRIPTION HP Heater In

45.9%

BMCR

250

MW *

60%BMCR

MAIN STEAM

Steam flow at SH Outlet t / h 772.78 1005

Pressure at SH Outlet kg / cm2 (g) 170.9 172.3

Temperature at SH Outlet o C 540.0 540

REHEAT STEAM

Steam flow at RH Outlet t / h 669.22 910

Pressure at HPT Outlet / RH Inlet kg / cm2 (g) 21.47 29.0

Temperature at HPT Outlet / RH Inlet o C 311.9 324

Pressure drop - RH kg / cm2 1.01 1.4

Pressure at RH Outlet / IPT Inlet kg / cm2 (g) 20.46 27.6

Temperature at RH Outlet / IPT Inlet o C 540.0 540

FEED WATER

Feed Water Temperature o C 219.2 235

Remark: 1) Boiler Parameters are based on Annexure-IV to MoM dated 7/7/2003 except for 60%BMCR

2) ** Maximum capability Point

3)* Performance Guarantee Points


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BOILER PARAMETERS( SLIDING PRESSURE OPERATION)

LOAD

DESCRIPTION HP Heater In

500

MW

400

MW

300

MW

250

MW

MAIN STEAM

Steam flow at SH Outlet t / h 1508.4 1193.5 895.1 753.3

Pressure at SH Outlet kg / cm2 (g) 168.47 134.59 101.72 85.73

Temperature at SH Outlet o C 540.0 540.0 540.0 540.0

REHEAT STEAM

Steam flow at RH Outlet t / h 1330.2 1060.7 801.8 660.0

Pressure at HPT Outlet / RH Inlet kg / cm2 (g) 42.79 34.17 25.77 21.18

Temperature at HPT Outlet / RH Inlet o C 338.7 340.2 342.2 340.4

Pressure drop -RH kg / cm2 2.00 1.59 1.20 0.99

Pressure at RH Outlet / IPT In let kg / cm2 (g) 40.79 32.58 24.57 20.19

Temperature at RH Outlet / IPT Inlet o C 540.0 540.0 540.0 540.0

FEED WATER

Feed Water Temperature o C 252.8 242.0 228.8 219.6


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VALVE OPERATING INSTRUCTIONS

BOILER DRAINS AND VENTS


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SYSTEM : CIRCULATION

SL NO TAG NO SERVICE DESCRIPTIONBOILER

FILLING

COLD

START UP

HOT

START

SHUTDOWN

WITH

COOLING

BOILER

EMPTYINGREMARKS

1 E16, E19 Eco Feed line drain, isolation & reg C C C C O2 E20, E21 Eco inlet header drain isolation & reg C C C C O

3 B1, B2, B23, B24 Drum air vent isolation O O(1) C C(2) O(3)

4 B3, B4, B20, B21 Drum purge &Bleed vent isolation O O(9) C C O(3)B5 & B22 to be opened

during N2 filling

5 B05, B22 Drum N2 filling isolation C C C C C(4)

6 B119, B120 Rear WW header drain isolation & Reg C C C C O

7 B114, B115 Emergency drum drain isolation & reg. C C(5) C(5) C C

8 E23 Eco recirculation line isolation O O O O O9 E22 Eco recirculation line regulating O O(10) O(10) C O

10 E17 Eco filling line isolation O C C C C

11 B118 Waterwall drain header drain C C C C O

12 B123 Boiler filling line isolation O C C C C

13 B108 Drum CBD isolation O O O O O

14 B109, B110 Drum CBD inlet isolation & blowoff C C(6) C(6) C C

15 B111 Drum CBD Bypass isolation O O O O O

16 B112, B113 Drum CBD Bypass isolation & blowoff C C(6) C(6) C CTo be opened when main

Line is not in use.

17 B116, B117 Bottom ring hdr blowoff isolation &reg C C(5) C(5) C O

LEGENDS

O OPEN

C CLOSE

O( ) OPEN EXCEPT AS INDICATED IN THE NOTE BELOW

C( ) CLOSE EXCEPT AS INDICATED IN THE NOTE BELOW

1 Open till 2.0 ksc (g) pressure. Close when pressure is more than 2.0 ksc (g). 6 Open according to chemists requirements and directions.

2 Close till 2.0 ksc (g) pressure. Open when pressure is less than 2.0 ksc (g). 7 Close after HP bypass is opened.

3 Close while emptying under Nitrogen capping. 8 Close just before raising vacuum in the condenser.

4 Open while emptying under Nitrogen capping. 9 Close before starting of Boiler water circulating pump.

5 Open to control drum level swell when required. 10 Close after continuous feed starts.

VALVE OPERATING INSTRUCTIONS



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O S S

SYSTEM : SUPERHEATER

SL NO TAG NO SERVICE DESCRIPTIONBOILER

FILLING

COLD

START UP

HOT

START

SHUTDOWN

WITH

COOLING

BOILER

EMPTYINGREMARKS

1 S88, S89 SH roof inlet header drain isolation & reg. C C C C O

2S15, S16, S17,

S18SH roof outlet header vent isolation. O O(1) C C(2) O

3 S86, S87 Backpass lower front header drains isoln & reg C O(1) C C O

4S84, S90, S85,

S91Backpass lower rear header drains isolation & reg. C O(1) C C O

5 S19, S20 Backpass rear upper header vent O C C C OS19 to be open during N2

filling.

6 S21 BP UPPER REAR HDR N2 filling - isoln C C C C C(4)

7S26, S27, S28,

S29SH - DESH link/SH finish platen inlet Link vent isolation. O O(1) C C(2) O

8S82, S92, S83,

S93SH Division panel inlet header Drain isolation & reg. C C C C O

9 S94, S95 SH Finish platen inlet hdr drain isoln & reg C C C C O

10 S31, S32 SH outlet header vent O O(1) C C(2) O S31 to open during N2 filling

11 S33 SH PLATEN O/L HEADER - N2 Filling isolation. C C C C C(4)

12S34, S36, S35,

S37SH Start up vent isolation & reg. C O(7) O(7) C C

13 S96 SH drain header drain isolation C C C C O

14 S97 SH filling line isolation O C C C C

SYSTEM : REHEATER

1 R42, R43 RH finish spaced outlet hdr drain Isolation & reg. C C C C O R 42 to open during RH filling

2 R09, R10 RH finish spaced outlet hdr vent O O(8) C C O R09 to open during N2 filling

3 R11 RH N2 filling isolation C C C C C(4)

4 R12, R13 RH outlet hdr Start up vent isolation & reg. C O(8) C C C

5 R44 RH filling line isolation O C C C C

LEGENDS

O OPEN

C CLOSE

O( ) OPEN EXCEPT AS INDICATED IN THE NOTE BELOW

C( ) CLOSE EXCEPT AS INDICATED IN THE NOTE BELOW

1 Open till 2.0 ksc (g) pressure. Close when pressure is more than 2.0 ksc (g). 6 Open according to chemists requirements and directions.

2 Close till 2.0 ksc (g) pressure. Open when pressure is less than 2.0 ksc (g). 7 Close after HP bypass is opened.

3 Close while emptying under Nitrogen capping. 8 Close just before raising vacuum in the condenser.

4 Open while emptying under Nitrogen capping. 9 Close before starting of Boiler water circulating pump.

5 Open to control drum level swell when required. 10 Close after continuous feed starts.

Unit Operating Procedures

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