Copy of Boiler

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QUALIFICATION BOOK

BOILER AREA

AES THERMAL POWER PLANT LAL-PIR

DISTRICT MUZAFFAR GARH

Fuel oil system 1

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Q.1.1:- Why it is necessary to remove water from oil tank before taking inservice?

Water in oil tank could cause following problems.

During HFO decanting water mixes with oil and it accumulates at the tank bottom,We know that moisture will lower the calorific value of fuel oil, so it is necessary todrain it otherwise following problems could occur in system.

1.Water in HFO could choke suction strainer in very short span of time becausewhen we heat the oil in suction heater it will causes the foaming on strainers mesh.

2.Accumulation of water will decrease the overall boiler efficiency, when it goes tofurnace with HFO, it consumes heat to evaporate so oil consumption will increaseand FCV will open more. Over all effect will be increase in heat rate and lower plantthermal efficiency.

Q..1.2: -: What is the fuel oil specification? What do you understand by CV?

Minimum fuel oil specifications are:

Calorific value should be equal or greater than 18200 btu/lb.Water should be < 0.3 %.Sediments should be < 0.15 %.Sulphur should be < 3.2 %.CV stands for calorific value.

Q.1.3: -What do you mean by dead stock level in fuel oil storage tank, why wekeep this level?

Actually we need to get dead stock of HFO because we have sediments and waterin oil, so they are settled in bottom (water % max. allowable is 0.30 and sediment %Max. allowable is 0.15).It could cause the differential pressure high problem on suction and dischargestrainers frequently. Even after draining the water of tank, it is possible that some ofwater pockets could remain in the tank, which could cause problem in the system.

Tank high level provides more absolute suction pressure to pumps then low levels.

Q.1.4:- Write the HFO tank low, low low, high and high high level alarm setpoints.Set points are as under:-

High 13.8metersHigh High 14.2Low 3.8Low Low 3.5

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Q.1.5: - How to put HFO tank bottom heating coil in service , also state theprecaution to do this job?

After settling time of HFO (36-48hrs) drain water in HFO tank from all three tankdrains.

Open the condensate return line isolating valves.Crack open TCV bypass valve.After 15-30minutes open TCV inlet and outlet Valves.Close TCV bypass valve.Make sure that bottom heater TCV controller set point is 40-45C.

Precautions: While draining water from tank, keep an eye on channel level anddrain valve should only be crack opened.

Gave warming time to bottom heater by opening TCV bypass line.Before starting heating steam, make sure that condensate return lines

valves are open.

Q.1.6: - What are the precautions before and during oil tank change over?Describe tank #3 change over which additional valves you will check other thannormal?

Following precautions and measures are necessary during HFO tankchangeoverAfter final tank dip reading by fuel group accumulated water should be drained fromall three drains of HFO tank.

Start heating of tank, temp should be 50oC before taking it into service.For Emergency we can take the tank in service at 40oC.Take suction heater TCV into service we can also open TCV bypass if required.

TCV should be on control from CCR and on auto from local box.Suction heater temp should be 40oC before opening tank outlet valve.First open tank outlet valve by one turn and maintain suction heater temp. And

dont allow it to down then 60oC, by this way open tank discharge Valve up to 100%.During HFO tank change over suction strainer DP alarm could come so in this casefirst change over the suction strainer and then proceed.After opening tank out let valve by 100% then close the outlet valve of that tank which

we are going to take out of service.Then open return line valve of coming in service tank and then close the outlet valveof goingoutservice tank.Tank suction heater TCV bypass valve should be closed and TCV should be on auto.Tank # 3:Procedure for tank # 3 is same as above except for one slight difference. Thisdifference occur because this tank is common for Pakgen & Lalpir.If lining up with Pakgen then close tie valves at fuel oil supply and return linestowards Lalpir and vice versa for Lalpir.

Q.1.7: -Describe the HFO pump suction strainer change over and cleaningprocedure.

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We assume that (a) suction strainer in service and (b) suction strainer is standby.First of all check that stand by suction strainer (b) inlet valve is opened and it isprimed.

Now open out let valve of stand by suction strainer (b), now both suction

strainers are in service.Close inlet and out let valves of suction strainer (a) very slowly andmake sure that pump sound is ok .Now open drain valve of suction strainer (a) and open its vent valve.

Check waste oil pit level, if necessary start waste oil transfer pump totransfer it to the oil separator storage pit.

Cleaning procedure of suction strainer:After completion of tag out, open the top cover of suction strainer (a) besure that there is no oil in suction strainer.Take out suction strainer, holding it strongly and clean its outer surface

with cotton rags then take this basket to the washing platform.Wash it with water and steam mixture thoroughly; during washing rub itwith wire brush (wet the brush with diesel oil).Wipe the basket with cotton rags.Then put the clean basket back into the suction strainer and close itstop cover with all bolts.

Now release tag out removes isolations.Close its drain valve.Crack opens its inlet valve to prime it, when priming is complete, open itcompletely.Now strainer is standby to use.

Q.1.8: - How to start HFO transfer pump? Explain pre- start and after startchecks?Before starting the pump:

Suction strainer should be in service.Pump suction heater should be in service & oil temp should morethen 70oC.Vent the air from pump by opening the pump pressure gauge and after that

little open pump suction valve after venting, close the suction valve and.. then put the P/G on its place.Then open pumps suction and discharge valve.

Open warning up line valve. (In case of one pump in service).Open PCV bypass two or three turns & PCV should be on auto and its ..

.. pressure should be adjusted at 30-32 bars.After properly warm up pump can be started.After starting the pump check the PCV and if it is controlling then slowly ..

.. start closing of its bypass valve. Check the header pressure whileclosing the PCV bypass.

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Q.1.9: - What is the purpose of pressure relief valves by pass valve at HFOtransfer pump?

To test the pump we must have to provide enough flow path to the discharge of HFOpump but if discharge valve is close we can test the pump by opening this valve.

Q.1.10: - Warm up line valve is open but stand by pump is not rotating, why?Explain your action.

It means that the pump is jammed, check the suction valve ,check the tracing steamof pump body & line and check the pump physically either it is warm or not. Possibleline of action in this regard will be to start the pump in the presence of maint: people.If it is normal then it may be kept in service by changing pump duty.

Q.1.11: - Write the isolation and depressurizing procedure of HFO pump formaintenance job. Explain normalization method after job completion.

Isolation & de-pressuring of HFO transfer pump.Off pump breaker from MCC.Close pump suction v/v, discharge v/v, warming line v/v , relive v/v& by pass v/v.Close tracing steam supply valve to pump and close steam trap inlet and

by .. pass valve.HFO pump can be de pressurized by opening its PG isolating valve.Valves should be tagged out properly.

After job completion, following steps will normalize the pump.Open suction valve of pump a few turns and then prime the pump by opening

.. its discharge PG after priming place the pressure indicator on its place.Open the line warm up valve.Open tracing steam for pump suction, discharge & casing andOpen steam trap isolating and bypass valve. Close trap bypassafter some time.Now open discharge valve.Normalize pump breaker.Now pump is ready for operation.

Q.1.12: - Write the isolation and depressurizing procedure of HFO dischargeheater for some repair job, also describe normalization method.

HFO pump discharge heater isolation and de-pressuring method.

Take heater out of service from CCR.Close TCV bypass and its isolating valve.Close steam trap isolating and bypass valve, and close tracingsteam inlet valve.Close HFO inlet and outlet valve.

Open steam side valve and also drain and vent the HFO side valves.Now heater is ready for repair.

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Normalization of HFO discharge heater after repair job:

Close the oil side drain valve and vent valve should remain partially open.Open heater oil side inlet valve a few turns to prime the heater

through vent line.After priming close the vent valve and open the discharge valve fully.Now open steam trap isolating valve and its bypass valve fully.Open TCV isolating valve.Gradually warm the heater by manual control of TCV or it can bewarmed also by opening a little TCV bypass valve.Open heater oil outlet valve slowly maintaining the oil outlet temperature.We can make heater standby by keeping TCV slightly open at manual.

Q.1.13: - What is the tag out procedure for HFO discharge strainer? What pre-

cautions to be taken during change over?

Take heater out of service from CCR.Close TCV bypass and its isolating valve.Close steam trap isolating and bypass valve, and close tracingsteam inlet valve.Close HFO inlet and outlet valve.Open steam side valve and also drain and vent the HFO side valves.

Now put tags and locks and get it verify from some one else now heateris .. ready for repair be careful while lifting the cover.

Prime the discharge strainer carefully, dont through cotton rugs intoor nearby the strainer.

Q.1.14: - Why we heat the oil before and after HFO transfer pumps. Describelow/ high, oil temperature effects on HFO transfer pumps and boiler? staterecommended temperatures set points ?

To decrease HFO viscosity we do oil heating, because it is easier to transfer lowviscosity oil then by high.Highly viscous oil cannot flow frequently in lines and could cause the pump motor to

over load and trip.Hot oil prevents frequently chocking of suction & discharge Strainers because highviscous oil could chock strainers easily.Low temp. Fuel cannot be fully atomized because of that proper combustion cannotbe achieved.

Temperature limits:-At suction of HFO pumps: 60 CAt outlet of discharge heaters: 115 C

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Q.1.15: - What is the function of HFO suction & discharge strainers, what arethe effects on the process if not changing the strainer after high differentialpressure alarm? What is the setting for suction & discharge strainer high DPalarm?

HFO have some amount of sediments and other particles in it, so suction anddischarge strainers are provided to prevent these things to jam the pump and toprevent to go into the burner tips, so they cant chock erode or damage the burnertips so that the efficiency of the unit remains constant.If we will not clean the suction strainer pump will trip at low suction pressure. If we willnot clean discharge strainer after high diff. Alarm FCV will go to 100% open due toless quantity of HFO & unit will go to run back and can tripped.Set point of strainer diff. Pressure is 0.2 Kg/cm2.

Q.1.16: - There is an excessive temperature variation at HFO discharge heaters.

How you will correct it?

Put temperature controller, for HFO discharge heater TCV, on manual and adjustopening of TCV by controller knob and watch temperature for 10 minutes, iftemperature is not ok adjust TCV opening again with the help of controller knob.

Q.1.17: - Both HFO transfer pumps in service. HFO discharge header pressureis low than normal, find the cause of this problem?

Check all system if there is any leakage, arranges to rectify it.Check pump house PCV set point and its opening.Check PCV by pass valve it should be fully closed.Check HFO pump relieve valve.Check FCV opening.If there is any abnormality, in any of the above-mentioned equipment,

immediately arrange to rectify it.

Q.1.18: -What will you do if stand by igniter oil or diesel oil pump is cut in onauto?

Check any leakage in the system.Check suction strainer of diesel oil system, if required change over the strainer.

After doing above checks try to stop one pump then put it again on auto ifpump does not cut in again then it is ok.

Q.1.19: -What is the operating method of waste oil separator? How it works,explain with sketch?

This equipment is provided to treat oily water and remove oil from oily water. This isdone by floating & separating it because of density of water and oil by gravity.

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Check drain pit oil level.Open oil-heating steam if required.Start the pit transfer pump and adjust its discharge pressure.Open the service water to oil separator inlet pit and adjust the flow.

Keep an eye on HFO flow towards the skimmed oil pit.Adjust the skimming pipe angle to permit HFO towards theSkimmed oil pit.Water will enter into filter area, if oil traces these, they should be removed.After ward filter water will go to neutralization basin through over flow line.

When skim oil pit level comes to maximum, stop the oil transfer pump and .... service water and empty the pit by vacuum truck.

Q.1.20: -How you will by pass HFO flow integrator, what pre-caution you willtake during this operation?

If some maintenance is required on HFO flow integrator then its by pass valve is tobe opened and to open it take FCV and combustion air on manual, with thecoordination of CCR, then open its by pass valve very slowly, approximately one turnper minute.While opening its by pass valve watch care fully, FCV opening, burner headerpressure, combustion air, boiler smoke and boiler burners, locally. CCR will watchload variation.

Q.1.21: - Draw diagrams of following systems.(a) HFO.(b) Diesel & Ignitor oil system.

Attached.

FEED WATER SYSTEM 2

Q.2.1: - Draw a sketch of Boiler feed water system from condenser to Boilersteam drum, with water pressures and temperatures at minimum and maximumload conditions?

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Q.2.2: - What is the duty of deaerator?

The basic duty of de-aerator is to remove dissolved oxygen from boiler feed water toeliminate the chances of corrosion.

Q.2.3: - What is the function of BCP? When 1st

and 2nd

BCP is started ?

BCP is provided for forced circulation of water in up risers.

1st BCP will be in service when drum level becomes more than normal water level.2nd BCP can be started when drum pressure will reach more than 30 Bar.

Q.2.4: -Describe BCP start up and its interlocks?

To start the BCP prior checks are as follows:-Steam drum level should not be low low

Cooling water flow should be normalCavity temperature below 57 CCavity turbidity should be normalInstrument air should be availableThen proceed to actual start activities:-Check steam drum level to be above normalMotor breaker should be normalInlet and outlet valves should be openCasing drain closedBCP cooler in serviceAfter taking air and gas cycle in service, start any one BCPIt is important to start BCP because it is one of the prerequisites of furnace purge.Second BCP will cut in on AUTO at above 30 Bar steam pressure.Q.2.5: - What is the function of BCP purge cooler, at which condition we haveto purge the BCP? Explain purging procedure?

The function o BCP purge cooler is to cool the BCP motor cavity filling water.

Conditions:

After shut done we do BCP casing filling by purging.

Purging procedure:

Fix Spool Piece.Open condensate water valve from turbine mezzanine floor.Open inlet valve to purge cooler.Open line drain valve.When clear water comes from the drain then close this drain.Open next isolating valve and drain valve when clear water comes then

Close its drain.

Open purge cooler inlet valve and flush the purge cooler

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through its drain valve.Open purge cooler vent valve and prime it.Open purge cooler outlet valve and flush the line.Open strainer drain and drain the water for some time.Open purge cooler strainer outlet valve.

Open isolating valve near BCP cooling water flow meter andalso open next drain and flush the line.

Open purge water valve to BCP motor.Open vent valve of BCP cavity and close it when clearwater comes through it.

Q.2.6: - How you will isolate the BCP for any maintenance job, also explainwarm up and normalization method after completion the job?

BCP Isolation Procedure:

Rake-out 11K.V breaker.Close both balancing line and suction isolating valves.Close both discharge and balancing line-isolating valve.Close BCP cooler inlet supply valves from condensate pumpand feed water pumps.Close BCP motor cooler inlet and outlet isolating valve if required.Open the drain valve and open the BCP casing vent.Close BCP Purge cooler cooling water inlet and outlet valve.

Warm up and Normalization method after maintenance job:

Close BCP drain valve.Flash the BCP cavity filling line by penning all the drains step by step.After flushing take sample of cavity filling water and check its conductivityand temperature.Fill motor cavity at slow rate and check the pump-casing vent, whenair free waters jet start coming from the vent that time close the vent valve.Open balancing valve of both suction valves.Start to open the suction valve.Open discharge valve.Warm up the pump by opening the warming valve and before starting the

. pump differential temperature between pump casing and drummetal temperature should not be more then 50'C.Cavity temperature should be normal.

Q.2.7: - What is the function of economizer re-circulation valve?

It is provided to recalculate the water from economizer inlet to water drum to avoidany excessive heating in water drum. Severe shock can occur and drum level will become impossible to control. To protect against steaming, economizer-recalculatinglines connect the water drum with economizer inlet header.

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AIR AND GAS SYSTEM 3Q.3.1: - Write down FDF & GRF pre startup checks?

Start checks for FDF :Air heater should be in service.

Air Heater pre-start checklist:Lube oil pump on auto or lube oil temperature less then 55 C.Instrument air and cooling water normal.

FDF start permissive:Air heater on.Both inlet and outlet should be in close position.Instrument air and cooling water normal. (Cooling water for the motor windingand bearings). Cooling water inlet and outlet valve should be opened.Lube oil of motor bearing and fan bearings should be normal.

GRF start permissive:One FDF must be in service.Instrument air and cooling water normal.Lube oil motor bearings and fan bearing should be normal.

Q.3.2: - How you will change FDF inlet vanes auto to manual and manual toauto from local?

Auto to manual: Turn the change over lever (co-axial with hand wheel) fully to manual.

Turn over change over knob (on front panel) to manual.Now you can control inlet vanes manually.

Manual to auto: Give a corresponding input signal with damper opening at manual operation

Then turn the change over knob (on front panel) to auto.Turn the hand wheel to find a position where it turns with out load (damperopening corresponds to input signal completely).Turn change over lever (co-axial with hand wheel) fully to auto.

Q.3.3: - What is the function of steam air heater, when it is necessary to takeninto service, describe sources of steam supply?

The function of steam air heater is to raise and maintain the proper air heater cold-end metal temperature by heating the combustion air during fuel oil firing. This

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prevents acidic attack on metal. The steam air heater is installed in the air ductsbetween the FDF and the AH.Start up procedure:

First open SAH steam line drain valve.Open main root valve to one turn to warm up SAH steam line.

After warm up completely open root valve and close the drain valve.Now open SAH TCV as per equipment.

Sources of steam =Aux steam & 5th extraction

Below 70% load steam is taken from Aux. Steam header and above that taken from#5 extraction of turbine. Consumption of steam at low load is about 40 tons/hr and athigh load is about 8 9tons/hr.

Q.3.4: - Draw steam & condensate system sketch of steam air heater?

Q.3.5: - Why air pre-heater is used in air & gas system. What are the starts upchecks for air heater?

The air heater exchange system transfers the waste heat of flue gas (fromeconomizer) to the combustion air. This improves plant efficiency because of therecovery of some of the heat in the combustion exhaust gas.The air heater absorbs waste heat from the combustion exhaust gas, and transfer tocombustion air by means of continuously rotating heat transfer elements of speciallyformed metal plates. This heat transfer will raise the temperature of cold combustionair approx. 270C.Pre start up checks:

Oil cooler coolant supply valve should be open.Before AH is put in service, confirm that the air driven motor is in Auto

position. The air motor is used to insure continued operation of the air heater rotor ifpower is lost to the electric motor.

Q.3.6: - When air pre-heater washing is required, what is max DP allowed?

When DP becomes more than 150mm of water then air heater washing is required.

Q.3.7: - What are the sources for air pre-heater rotation, mention the RPM of air

heater?

Normal air heater rotation is with an electric motor but air motor is used in case ofpower lost and in case of complete blackout air heater is rotated with a manual hand-cranking lever, provided to rotate the rotate the air heater during the blackout period.

Air heater is rotated by electric motor at 1.42 RPM.

Q.3.8: - At which situation you have to move air heater motor by hand? Whatare the precautions to do this job?

In case of black out and when emergency power is not available then we are required

to rotate AH motor by hand.

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Before rotating it by hand ask CCR to open its breaker (from emergency bus) andlock it from CRT.

Q.3.9: - Describe the purpose and source of sealing and cooling air also writethe names of equipment where sealing and cooling air is being used?

Purpose of sealing and cooling air:

This system is provided to prevent leakage at air and gas system and from boiler thesystem seals furnace gas and exhaust gas in the boiler.The system prevents some equipment from overheating .Sealing and cooling air source is cooling air fan (AC or DC).Equipment where cooling and sealing air is provided.

TV camera.All burners and Igniters scanners.Peep holes.

Tampering air.Wind box dampers shaft seals.Burner air seals.GRF shaft and inlet dampers seals

Q.3.10: - What you check if any air and gas damper does not opens?

Check opening position of damper and its limit switch, locally. If damper is open andlimit switch is not giving signal, knock the knob of limit switch.If damper is in close position, open it by its cylinder air supply solenoid valve.

Q.3.11: - DC cooling fan has cut in on auto, check the cause of start up andcorrect it.

If normal running A/C cooling fan trips the DC cooling fan will start.If ( Wind box Furnace) discharge PCV stop working.Start A/C cooling fan and stop DC cooling fan, Check PCV and rectify and if theinlet(Suction) strainer is chocked then clean it and start A/C cooling fan.

COMBUSTION SYSTEM 4Q.4.1: - What is furnace, why it is provided with high-pressure protection, whatis the set point for Lal pir and Pak Gen boiler? Where are the switches located?

Furnace is enclosed area where burners are located and combustion of fuel occurs.Water walls surrounds the furnace and absorb the heat of combustion. The furnace isprovided with high-pressure protection to avoid furnace explosion and infiltration ofgases in air passage and other equipment like GRF fans. Pressure switches arelocated at 6th floor.

Pressure switch set points:

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LALPIR: 600 mmH2OPAKGEN: 710 mmH2O

Q.4.2: - Explain the permissive conditions to start the furnace purge? What isthe duration of purging in our Boiler and why it is important?

Following are the permissive conditions for furnace purge:Igniter oil conditions full filled.Diesel oil conditions full filled.All burners shut off valves closed.All flame detectors off.All aux. Air dampers modulated.Airflow more then 30% of BMCR.Any FDF on.

Any GRF on.Any BCP differential pressure normal.MFT exist.

Furnace purge duration is 5 minutes, the furnace purge is done to remove anyunwanted air or unburned fuel or combustible gas from the furnace and it is done tomake sure that only fresh air exists hair and no any combustible mixer is there in thefurnace.

Q.4.3: - What is the purpose of the leak test, what will be your action in leak testbeing failed repeatedly?

The purpose of this test is to check weather any burners shut off valve of diesel oil orHFO is passing or not and by leak test we can make it sure. If any Diesel Oil or HFOburner shut off valve is passing it can cause fuming of oil molecules in furnace andthose fumes could cause explosion during first fire.

If any Diesel Oil or HFO or Igniter oil leak test fails, following steps could be taken.

During leak test when we go to opening main shut off valve of fuel at that time justcrack open burner header vent valve when main fuel shut off valve is going to close

immediately close the vent valve, with the help of this we can remove air from burnerheader.If any burner shut off valve is passing then close its Manual isolating valve andtry to fix this problem.

Q.4.4: - Write down burner ON permissive & light off sequence give all stepswith time.

Burner start permissive:Oil temperature should be greater than 90 C and less than 130 C.Furnace purge and leak test should be complete and MFT reset.

Atomizing steam and air pressure should be normal.

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Light off sequence:Give burner ON command. Igniter will fire.Gun will advance.Atomizing steam or air valve will open.Fuel valve will open.

Stop sequence:Give burner OFF command.Igniter will fire.Burner fuel valve will close.Purge and atomizing valve will open.After 1 minute atomizing valve will close.After 2 minutes atomizing valve will open.After 1 minute purge and atomizing valve will close.Gun will retract.Igniter will turn off itself.

Q.4.5: - What is the capacity of main burner, give burner header pressure low &high set points, Why are they provided?

Capacity of main burner is 5.125 tons/hr. Low pressure set point: 12 Kg/ cm2.Low low pressure setting: 7 Kg/cm2.High pressure setting: 27 Kg/cm2.

If header pressure is low fireball will be improper and since airflow is same and fuelpressure is low, airflow ratio will be affected. Combustion will be unstable and flamewill get weaker and might extinguish. If header pressure is high then again fireball willbe improper and atomization of fuel will be improper.

Q.4.6: - What are the basic causes of furnace explosions, how it can beprevented?

The basic cause of furnace explosion is accumulation of unburnt fuel.Combustible or explosive gases inside the furnace.Increase in furnace pressure due to chocking of AH.

Preventions: To avoid accumulation of unburnt fuel, we perform HFO leak tests.

We observe D/P of AH and do washing when it requires.During outage boiler is cleaned/inspected thoroughly to avoid anyinterruption to flue gases.

Q.4.7: - What is the function of atomizing steam? What will your action if

atomizing steam pressure is decreased also write the effect of low atomizingsteam pressure at Boiler?

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Atomizing steam atomize the HFO in very fine particles for complete combustion. Ifatomizing steam pressure is going down then take following immediate steps.

Try to improve aux steam header pressure by adjusting its set point.

Check atomizing steam PCV for any damage.Otherwise close decanting steam supply valve to improve pressure of

aux steam header.If after taking those steps aux steam pressure is not improving thentake steam jet air ejector out of service.If still pressure is not improving then get aux steam from both aux

steam sources i.e. from 3ry SH inlet header and from cold reheat. Bytaking both MOVs on Manual so by this way aux steam headerpressure will increase.

If low atomizing steam pressure occurs:

Atomizing steam pressure low alarm will come at 7-bar and boiler will tripat 5-bar pressure.Combustion will not take place properly so due to that excessive fuelconsumption may take place.Smoke will also become dark due to in complete combustion.Again FCV of HFO will more open to meet fuel demand.

Q.4.8: - Explain the term of damper. What is the function of fuel and aux. airdampers? Write their positions during burner off & ON conditions, how windbox pressure is controlled?

Damper is a device, which is used to control or regulate the volumetric flow of gasand air.Fuel air damper opening varies with fuel pressure when the burner is in service. Itremains fully close position when burner is out of service.Aux air dampers supplies air for secondary combustion it is controlled by BMSsystem depending on the boiler load. It maintains the differential pressure betweenwind box and furnace.

Wind box pressure controlled through aux air dampers.

Q.4.9: - What you will do, if a burner gun did not retract after shut down? Writethe result of delay to normalization?

Following steps can be taken if a burner gun did not retract even after shut down ofburner.

Locally retract burner gun by pressing its solenoid.If it is not retracting take it out mechanically(manually).We can open aspirating air source to provide some cooling air toBurner tips.Solenoid valve of atomizing steam shut off valve can be provided to

some cooling media to burner gun tip.

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If burner gun will remain inside for more time burner tip could be damaged.

Q.4.10: - What you have to do, if ;(a) Igniter fails to ignite.(b) Burner header oil pressure high.

(c) Burner gun has advanced but fuel & steam supply valves did not open.

Igniters fail to ignite:Try to ignite it by adjusting fuel and air valve manually.Check the spark plug.Clean igniters oil strainers.Check air filter.Check igniters wind box pressure.Flame detectors should be cleaned.

Burner header oil pressure if becomes high:Check PCV opening and it can be taken on manual for maintainingBurner pressure should be checked.We can open equalizing line MOV to release some pressure.Burner guns should be cleaned.

If burner gun has advanced but HFO and atomizing steam supply valvedid not open:First make sure, has the burner gun touched the limit switch or not.In case of no touching the burner gun to limit switch then adjust thegun position.Check that is the gun fully advanced or between advances retractsposition, if like that then rectify problem.We can open atomizing and fuel valve by pressing the limit switch

Q.4.11: - Write the replacing and cleaning way of burner guns? Whichprecautions you should have in your mind to do this job?

Replacing and cleaning way of burner guns:

Shut off burner from control room and then put it on sub group.Burner gun should be off purge and retracted.Close fuel and atomizing source isolating valves.Open aspirating air valve.Lose the local nut for burner gun and remove the local latch.Pull out the gun.Remove old gas kit and put the new gas kit after cleaning the surface ofgas kit seat.

Cleaning burner tip.

Put the gun on cleaning stand.

Remove burner tip.Clean the nozzle cap, spray plate, and back plate.

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Inspect the burner assembly and parts for any corrosion erosion orany damage.

Hole size should also be checked.

Insert the clean gun inside.Latch the local and tight the latch nut.Close the aspirating air valve.Normalize the fuel and atomizing steam-isolating valve.

Q.4.12: - Explain the properties of good combustion? How we can verify thatboiler combustion is ok?

Properties of good combustion. Oxygen and fuel ratio should be proper.

Atomizing of fuel should be proper.

Fuel temp. Should be proper for healthy fuel burning.

Verification of good combustion. Smoke should not be dark it should be light brown.

Flue gas analyzer should show some percentage of oxygen, whichis a verification of complete burning.Flame color should be proper and in orange color, we can watch iton TV screen in CCR and also on local.

Q.4.13: - What is re-heater protection? How does it operate?

At the time of boiler start up, to avoid the over heating and damaging of re-heaterpressure or open its by pass valve slightly to regulate pressure .tubes and

to limit the boiler firing rate to control furnace exit temperature of flue gases followingprotections are provided.

If difference between fuel supply and return is greater than 30% of MCR andmain steam flow is low low then re-heater protection operates with time delay of 10seconds. In another case if fuel flow difference is greater than 17% of MCR then re-heater protection operates with time delay of 20 seconds.

Q.4.14: - What are boiler interlocks explain in detail.

If boiler tripping occur,all fuel oil system (fuel shut off v/v) will be shut down simultaneously.

The Boiler will trip under following conditions:-Emergency boiler trip PB on (manual trip).Re heater protection.All FDF stopped.Air flow low low (


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Unstable fuel supply.Boiler trip request from turbine interlock.APC failure.

MAIN AND REHEAT STEAM SYSTEM 5

Q.5.1: - Draw a sketch of main steam cycle from steam drum to 3ry SH andheader along with pressure and temperature at minimum and maximum loadconditions?

Attached.

Q.5.2: - Draw a sketch of reheat steam cycle from HP turbine outlet to IP turbineinlet, showing with pressure and temperature at minimum and maximum loadconditions?

Attached.

Q.5.3: - What are the steam conditions for turbine rolling? at(a)-Cold start(b)-Warm start and(c)-Hot start.

For cold start up main steam pressure should be > 60kg/cm and main steamtemperature should be 350C 420C.

For warm start up MSP should be > 80kg/cm and MST should be > 360C.

For hot start up MSP should be > 100kg/cm and MST should be > 400C.

Q.5.4: - What is the purpose of S.H & S.P header drain valves and vents valves?Write their opening/ closing position during start up and shut down?

The vent valves are provided to remove unwanted air from the system and they arealso used to drain the SH and SP heaters. Close these vents when drum pressurereaches at 2bar.When pressure reaches at 30bar close the 2ry SH drains and when the drumpressure reaches up to 40bar then close the blower header drains.Close the 1ry and 3ry SH drains when required pressure and temperatures andachieved.If we do complete shut down of boiler then open all the vents and drains and in caseof hot banking close all the vents and drains.

Q.5.5: - How main steam temperatures is controlled?

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Main steam temperature is controlled by installing de-super heaters between 2ry and3ry super heaters.Q.5.6: - Why de-super heater is located on 3ry S.H inlet header?

A de super heater function is to get required temperature by decreasing enthalpy,

When we add water in 3ry inlet heater in that way we increase steam mass anddecrease enthalpy (latent heat & sensible heat) so when it enters in the 3ry SH then itgets the required temperature.

Q.5.7: - How re-heat steam outlet temperature controlled?

Here are some tips to control hot reheat steam temperature.De-super heater at cold reheat steam line.If we open GRF inlet guide vans more, re-heater temperatures willrise more.By burner tilt mechanism we can raise RH steam temperature

Q.5.8: - At cold reheat steam line we have six safety valves and at hot reheatsteam line we have only two, why?

Our re-heater metal is not design for high pressure, so when our unit trips,these six safety valve of cold reheat line try to maintain the cold re heat line pressurebecause when turbine trips its MSVs & RSVs go to full close and the total re-heatline from hot to cold end gets pressurized so cold re-heat line have more pressurethen hot re-heat line and these are the last protectionof re-heater.

BOILER CHEMISTRY 6

Q.6.1: - Explain in detail boiler water chemistry, what are the limits & how theseare controlled?(a) pH

(b) Conductivity(c) Ammonia(d) Hydrazine(e) Phosphate(f) Silica.

Boiler water chemistry and the control ,

pH for condensate, feed water and steam should be 8.8 9.5and 9.0 9.5 for drum water.

Conductivity for condensate, feed water and steam should be2.0s/cm to 6.0s/cm and less 50s/cm for drum water.

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Ammonia concentration is checked in condensate and steam its concentrationshould be less than 1.0ppm. Ammonia concentration is increased to increase the pHof the boiler system. Some time at full load hydrazine starts to convert into ammonia

at that time we control excessive ammonia by increasing the opening of de-aeratorby pass vent valve.

Hydrazine is being dosed in feed water and should be greater than 10ppb. Itsdosing control done by the hydrazine feed pump strokes.

Phosphate is dosed directly into the drum water to increase the pH and to avoid anyscaling. Its limits are 0.5 2.5ppm. If phosphate is dosed in excess amount than itcan be removed by opening the boiler CBD.

Silica control done with the help ofCBD it should be less than 200 ppb.

Q.6.2: - Describe the procedure of the following tests;(a) Ammonia(b) Hydrazine(c) Phosphate(d) Silica

AMMONIA ANALYSISTake 25 ml sample in 50ml conical flask.Start DR/2010 Spectrophotometer. After self test the display will show Enterprogramme #. Press 951 or press up/down arrow key to get 951 on display screen.Adjust the wavelength at 425 nm by rotating the knob clockwise/ anticlockwise.Add one ml of Ammonia reagent (Nesslers Reagent) and mix.Press SHIFT + TIMER key at photometer. Five minutes wait time will start.After five minutes, photometer will give a beep, put Demi. water in cell above markand insert in sampling compartment. Press ZERO key.Fill the second cell above mark with sample and put it in place of first cell. PressREAD key to get the reading.

HYDRAZINE ANALYSIS

Take 25 ml sample in 50ml conical flask.Start DR/2010 Spectrophotometer. After self test the display will show Enterprogramme #. Press 952 or press up/down arrow key to get 952 on display screen.Adjust the wavelength at 450 nm by rotating the knob clockwise/anticlockwise.

Add 5 ml of Hydrazine reagent (4-Dimethylamino-benzaldehyde) and mix.Press SHIFT + TIMER key at photometer. Ten minutes wait time will start.After ten minutes photometer will give a beep, put Demi. water in cell above markand insert in sampling compartment. Press ZERO key.Fill the second cell above mark with sample and put it in place of first cell. PressREAD key to get the reading.

PHOSPHATE ANALYSISTake 25 ml sample in 50ml conical flask.

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Start DR/2010 Spectrophotometer. After self test the display will show Enterprogramme # . Press 953 or press up/down arrow key to get 953 on display screen.Adjust the wavelength at 650 nm by rotating the knob clockwise/anticlockwise.Add 1 ml of phosphate reagent # 1(Ammonium Molybodate + 50% Sulphuric acidsolution) and mix.

Add 3 drops of phosphate reagent # 2 (Stannous Chloride + Hydrochloric acid) andmix.Press SHIFT + TIMER key at photometer. Five minutes wait time will start.After five minutes photometer will give a beep, put Demi. water in cell above markand insert in sampling compartment. Press ZERO key.Fill the second cell above mark with sample and put it in place of first cell. PressREAD key to get the reading.

SILICA ANALYSISTake 25 ml sample in 50ml conical flask.Start DR/2010 Spectrophotometer. After self test the display will show Enter

programme # . Press 954 or press up/down arrow key to get 954 on display screen.Adjust the wavelength at 820 nm by rotating the knobclockwise/anticlockwise.Add 1 ml of Silica reagent # 1(Ammonium Molybodate + 50% Sulphuric acid solution)and mix.Press SHIFT + TIMER key at photometer. Five minutes wait time will start.After five minutes photometer will give a beep, add 1 ml of Silica reagent # 2(OxalicAcid) and mix. Press SHIFT + TIMER key. One minute wait time will start.After one minute photometer will give a beep, add 1 ml of Silica reagent # 3(4-MethylAmino Phenol Sulphate + Sodium Disulphite) and mix. Press SHIFT + TIMER key.Ten minute wait time will start.After ten minutes photometer will give a beep, put Demi. water in cell above markand insert in sampling compartment. Press ZERO key.Fill the second cell above mark with sample and put it in place of first cell. Press

READ key to get the reading.

Q.6.3: - At which point we are injecting phosphate in our main Boiler? Explainits function with the help of chemical reaction, write its safe limits and effectsof excessive dosing?

We are injecting phosphate at BCP suction.

Function of phosphate:It is used to raise the boiler drum pH .If there is more hardness in system then phosphate reacts with hardness and

converts this into tri calcium phosphate or bi calcium phosphate that can be removedthrough blow down. Due to which we can reduce the Hardness in boiler drum water.

Chemical reaction:

3CaCO3 + 2Na3PO4 Ca3(PO4)2 + 3Na2CO3.

Na2HPO4 + CaCO3 _________ Na2CO3 + CaHPO4Safe limits of dozing:

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0.5 To 2.5ppm.Excessive dosing effects:

PH can increase.Conductivity of system will rise.It could cause foaming in boiler due to which carry over could occur.If both of these conductivity and pH increases in feed water system, that could

cause caustic embrittlement, due to which inter crystalline cracking of boiler metalcould happen.

Q.6.4: - Which chemical is being used for O2 removal in our plant? What is thecontrolling limit and what precautions should be taken to handle that chemical,what is the chemical reaction?

De aerator remove un dissolved gasses from the system.

When water is heated in vessel, solubility of gasses decreases at certain pressuredue to flashing and by this way these unwanted gases specially O2 escaped from thesystem. It also helps to raise the feed water temp.Hydrazine (N2H4) is used for the removal of O2 in our plant.

Its dozing rate should be 10-20 PPM.

Safety precautions in chemical handing:

Chemical handling station safety shower should be in service.All accentual PPE in which splash glasses, safety suit, rubber gloves, face shield

and rubber boots are included should be used

Chemical reaction:N2H4 +O2 ______ 2H2O + N2

Q.6.5: - How silica level may increased in Boiler water? What are the maximum

allowable limits, what will you do, if silica is increased in Boiler water? Silicalevel can increase due to following reasons:If Demi. plant is not able to produce low silica water.Due to condenser tube leakage.

Maximum allowable limits of silica:

Main steam: MAX 20ppb.Steam drum: MAX 200ppb.

If silica increase in boiler feed water:

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Open CBD to control silica.Check the Demi. plant silica.And perform trace Silica testsCheck the condenser tubes leakage one by one isolatingthe condenser south and north sides.

Q.6.6: - What is the purpose of vanadium inhibitor dosing, and how it protectsthe tube metal from corrosion?

When we burn fuel in the boiler it leave some ash with boiler tube and this ash cancase corrosion Fire Mag 2900 is a magnesium oxide (MgO). It is use as vanadiuminhibitor. Vanadium penta Oxide forms hard scaling(Sodium Vanidate) on the reheater tubes. Which reduces heat transfer rate from hot gases to steam flowingthrough the super heater and re-heater tubes. Fire mag is pumped into the HFOburner header with the help of fire mag dozing pump in proportion 99.6 ML portion of

HFO at full load. The Vanadium solution provides media for rapid diffusion of Oxygento unprotected pure metal surface. The chemical reaction of fire mag with vanadiumis:

MgO +V2O5 _______________ Mg3V2O8

The melting points of magnesium Oxide, vanadium oxide and Magnesium vanidateare 270 oC, 650 oC and 1150 oC respectivelyDue to Fire Mag dozing soot forms a soft scale of magnesium vanidate on re-heaterand super tube, which can be removed easily by soot blowing.By dozing the vanadium inhibitor the hi pressure section remain free and cleanthrough these corrosive deposits. The deposits are dry and have alkaline PH.Excessive powder is taken away in the gas or can be blown away by soot blowing.

Q.6.7: - Describe the method to take air heaters soot samples?

Wear all PPEs (gloves, glasses, mask etc..) open sampling port flange bolts and takeout soot collecting rod, take soot on the paper and re-fix the soot collecting rod, fixthe cover back and take this sample to the lab for testing.Similarly get the soot sample from other port.

Q.6.8: -How you will check air heater soot pH, what are the recommended limits

for pH and sodium hydroxide consumption.

We will dissolve the one gram of soot in 100ml of Demi water and the we will checkthe ph of this after agitating this for five minutes and one more reading after 55minutes it should be near by or in between2.5 to 3.5,after this we will place thissolution on magnetic agitator again and the electrode of ph meter also placed insolution, now start to add 0.1 M NaOH to this so that the ph of this becomes 8.0now see how much NaOH consumed(It will be near about 1.5 ml).

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SAFETY 7

Q.7.1: - Describe the safety precautions involved in handling of Vanadium

inhibitor, Sodium hydroxide, Ammonia, Hydrazine and phosphate.

Possible risk in case of improper handling could lead towards harm to you and yourteam mates.In case of contact with eyes rinse immediately with plenty of water seeks medicaladvice.After contact with skin, wash immediately with plenty of soap and water.So be care ful during the transportation & shifting of these items and dont swallowspecially protect your self with the help of suitable protective clothing, gloves andeye/face protection.

Q.7.2: - Define confined space, write the safety measures to be taken to start ajob in confined space.

A space which may have the potential to contain a hazardous atmosphere, amaterial that could engulf an entrant or the entrant could be trapped or beasphyxiated or the place that has not been designed for continuous humanoccupancy or contains any other recognized serious safety or health hazards.Prior to start a job in confined space these thing are necessary to check:-FTemperature in the confined space, Oxygen concentration, flammability, toxicmaterial or gases. An authorized attendant should be designated as hole watchand he should have the appendix a,b,c & a-1 for the registration of people going to

work in side, person should have paging radio , first aid box and fire extinguisher andbe sure that no other way will be used by people going in and coming out, placeDANGER tags on the all other hole to protect the un authorized entry.

Q.7.3: - What systems are provided for fire fighting on the boiler? Drawdiagrams.

Fire Hydrants are located at various points. Deluge valve system is installed atimportant locations (near BFP & HFO pump houses). Portable fire extinguishers arealso provided.

Q.7.4: - Explain how to reset a deluge system what type of deluge system isinstalled on boiler?

Following steps are to be followed to reset deluge valve system after operational testof the system or after system operation due to fire.

Close the diaphragm chamber supply valve.Close the main control valve.Open the main drain valve and all aux. Drains in the system.Close the aux. drains after the water is drained and leavethe main drain open.Depress the plunger of the automatic drain valve to verify that it is open.

Push the reset knob inward to allow the clapper reseat.

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Clean the strainer in the diaphragm chamber supply connectionby removing the clean out plug and strainer basket.Reset the actuation system.Open the diaphragm chamber supply control valve and allowthe time for full pressure to build up in the diaphragm chamber.

Operate (open) the manual control station to vent the trapped air.Inspect drain connections from the manual control station, solenoid

valve, .. .. .. actuator and alarm devices, any leakage must be corrected beforeproceeding to the next step.

Slowly open the main control valve, close the main drain valve as soon as waterdischarge from the drain connection. Check if there is any leakage other wise systemis ready to placed in service.

Q.7.5: -where are the deluge valves located at boiler area?

Deluge valve system for boiler area is located near BFP.

Q.7.6: - How you will detect air pre-heater fire and when it is most likelyhappen, describe your action at that time?

An air heater fire can be detected by the following observations:Exhaust gas outlet temperature will rise.Due to soot burning, air heater DP may increase.Fire can be observed from peephole.

Due to the high DP of air heater, fire is most likely to occur because Sulphur is acombustible material. High differential pressure may arise from extended low loadoperation due to probable instability in combustion and low flue gas velocity.

To rectify this start soot blowing, the hot-caustic washing devices are fitted atboth ends of the stationary header. The washing devices can be used for fire fightingin case of an Air Heater fire. Close flue gas and air side inlet/outlet dampers if fire isnot controlled.

BOILER AUXILIARIES 8Q.8.1: -Write the auxiliary steam sources and uses.

WE have four sources of aux. Steam supply to aux. Steam header.Aux. Boiler: In case of boiler shut down and start up positions.Aux. Steam tie valve between unit 1 & 2 to give and take aux. Steam from other unit.It is also used in unit shut down and start up conditions.

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3ry super heater inlet header steam supply. It is used in unit low load, shut downand start up conditions.Cold reheat. It is used when load is >50%.First open traps by pass valves and drainsof aux. Steam header then slowly feed the steam to the system when all condensate

is removed, close the drain valve of aux. Steam header when its pressure is reachedto 15bars and temperature reaches to 250C then the aux. Steam can be supplied tothe related systems.

Q.8.2: - How to take Auxiliary steam header in service during start up?First open the drain and when the color of steam becomes colorless & headerbecomes warm, you can charge it from tie or from Aux boiler because when pressurewill reach the 30 Bar mark the steam will start to come from 3ry super heater.

Q.8.3: - What are the precautions to open the Aux. Steam inter connectionvalve? Which valve you will open first?

Crack open Aux. Steam interconnection valve of boiler (in service).Open drain valve of other unit to drain the condensate.When steam starts to come from drain line of other unit then close it.Slowly open the tie valve of unit in service.Open trap by pass valve of main steam header for aux. Steam.Open tie valve of other unit.Then close trap by pass valve when steam starts to flow.Now we can use aux. Steam for the other unit.

Q.8.4: - Aux. Steam MOV from 3rySH side does not close fully from CRT, howto close from local?

First of all set its local supply switch from remote to local Then operate it from 2 nd

knob which is for opening and closing.

If it is not operating by above given method then change its selection from local tostop and by pressing its clutch/lever and operate it by its hand wheel.

Q.8.5: - What is Aux. steam header set point, where its controllers are located?

Aux. Steam header set point is 15 16bars.It is controlled by PCV provided at cold reheat side, its controller is on 4 th floor and itsvalve is on 5th floor.3ry steam headers PCV (02nos) are located at 7 th floor on boiler east and itscontroller is near main steam line safety valve just below the 7th floor.

Q.8.6: - Write the all steps to start aux. Boiler from pre-start to line up?

Preparation for aux boiler startup:

Demi. waterline up aux boiler start up.Steam converter condensate storage tank should be normal.

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Level gauge glasses should be line up.Open aux boiler vent valve.Make Aux boiler level up to 60% gauge glass if need to make waterLevel 60% then make its level 60% by manually starting of feed pump.After make up of required 60% level, put one feed pump on auto and make

sure that stand by pumps are working proper.Make sure that aux. boiler main steam root valve drain valve of drum and de-aerator is closed.If steam converts condensate is going to LP2 it should be diverted to auxboiler.Pilot torch diesel oil tank should have enough dieseloil level.

Start aux boiler diesel oil pump.Release emergency push button.Switch on the main control switch.First reset the burner control cabinet inside the control panel and then reseton the control panel.

Switch on the burner switch and the air and gas system will startautomatically.Furnace purge will start for three minutes.Igniter will be on and main burner will fire after 10 seconds.

Close the drum vent valve at 1bar pressure.Later burner will start cut in and cut out at 16.5bar to 17.5 bars respectively.Feed water pump will cut in and cut out on auto to full fill the water levelrequirements of boiler drum.

Q.8.7: - Write the start up and shut down procedure of steam converter?

Start up procedure of steam converter.Open LCV bypass valve to make the condensate storage tank level 75%. Close thebypass of receiver after filling and put its LCV on auto with 75% set point. Open LCVby pass of re-boiler and put its LCV on manual mode.

Now start one fed pump and put other pump on stand by mode.When re-boiler level reach at 60% level then close the LCV by pass andput LCV on auto with the set point of 70%.Close the re-boiler steam outlet valve and line up primary steam system and

select primary steam inlet control valve on auto and give a set point of 1.5 bar and

when this pressure is achieved then start set point increasing with adding a set pointof 0.5 bar.Watch primary steam condensate level and when it is reached at 60% then put

the primary condensate LCV on auto with a level set point of 60% either towards ofLP2 or blow down. When secondary steam pressure reaches 9.5 to 10 bar then re-boiler outletvalve and place steam converter by pass steam pressure controller on auto with setpoint 9.5 bar, also place secondary steam TCV on auto with a set point of 184O C.

After four hours of operation at the level set point open the manual blow downvalve from the re-boiler to discharge blow down at a rate that will prevent boiled updissolved solids.

Steam converter shut down procedure

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Check that de-super heater line up is OK when steam converter is going toshut down, de-super heating will be done by secondary condensate feed water lineand TCV set point will be put about 190o C to 200o C.

Put secondary steam PCV on auto and primary steam PCV on manual and

slowly decrease its valve opening to stop heating steam. During this check steamconverter bypass steam is on line.

When re-boiler by pass takes full control you can close heating streamisolating valve and re-boiler outlet valve. Fill re-boiler with water fully to down the metal temp.

If we want to empty the re-boiler then open its vent valve at one bar pressureand one range valve of cell and tube side 0 bar pressure.

Q.8.8: - How steam converter is producing steam? Draw a sketch forexplanation?

This system is designed to produce steam 12500/Kg per hour at a pressure of 9.0barand a temp of 184oC. When supplied with primary steam of 14.3 bar pressured and205oC temp.

This steam is used for tracing and heating of HFO lines and heaters.Condensate return from the system is received in condensate receiver tank.

The level of condensate receiver is also maintained by a LCV and Demi. wateris used for make up. We two feed pumps for re-boiler. One working and one standby. These pumps take suction from condensate receiver tank and discharge feedwater to re-boiler. Flow is regulated by a LCV, which is based on level control of re-boiler shell side. A flow transmitter is also provided on common discharge of re-boilerto watch the feed water flow to re-boiler. A pressure-regulating valve is providedwhich opens at the time when re-boiler level goes to an adequate limit. Feed waterpasses through the tube side of condensate cooler before it enters into the re-boiler.Feed water is preheated by the primary condensate leaving for LP2 heater. This feedwater is enters into the shell side of re-boiler through a de-aerator and primary steamfrom aux steam header or aux boiler is entered into the tube side of re-boiler througha PCV, that is directed by a PIC which gets the signal from secondary steam whichleaves the re-boiler.

Primary steam which enters the tube side of re-boiler after transferring heat tosecondary condensate it leaves the tube side of re-boiler and enters the shell side ofcondensate cooler which warms the secondary feed water after that it leaves for

either LP2 side or cooler which warms the secondary feed water after that it leavesfor either LP2 side or aux boiler de-aerator side or to the blow-down. One LICcontrols the level of condensate cooler. Primary condensate can also be diverted toany of unit 1 or unit 2 LP2 heater through an interconnecting line.

When re-boiler is down for maintenance job we can make secondary steamdirectly by primary steam using a de-super heater with the help of a TCV, it getscooling water from re-boiler feed water pumps discharge line. In that case secondarycondensate is directly converted to the blow down basin. (Blow down is return fromthe system continuously through a manual valve on the bottom of re-boiler shell it isnecessary to avoid the undesirable concentration of dissolved solids that willeventually foul the heat transfer surface.

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Q.8.9: - Both feed pumps of steam converter failed to start, check and rectifythe fault?

Check condensate tank level.

Check suction valve is open and limit switch contact is O.K.Check breaker in MCC room, if it is tripped reset it.Check selection of pump at local.Check local panel, if any alarm is standing reset it.

Q.8.10: - How steam converter steam outlet temps and pressure controlled.What is main use of secondary steam, what will happen when steam converteris out of service?

Steam converter pressure is controlled by opening of primary steam (heatingsteam) control valve, Primary steam PCV opens and closes to control secondarysteam pressure, as per given set point at controller, when ever it decreases orincreases.Its temperature is controlled by its TCV; if temperature is high its TCV will open andspray condensate water, which is coming from steam converter condensate pumpoutlet line.We require a separate heating system for fuel heating and tracing because in case ofany leakage in fuel heat exchanger oil is more likely to enter in our main system thatis why secondary steam and its condensate is kept separate.Uses of secondary steam:

HFO tank suction heater.HFO tank bottom heater.HFO discharge heater.Tracing of fuel pipes.

When steam converter is out of service, primary steam (heating steam) will go to allthe system and will come back to condensate tank and drain in blow down basin.

Q.8.11: - Why primary steam condensate is recovered and where it is diverted?

Primary steam condensate is recovered to avoid wastage of demin. Water, which iscostly.After doing its work in steam converter, primary steam passes through convertercooler, here it transfer its heat to in coming feed water and changes in to condensate.This condensate can be diverted in three places.

To LP2 of same unit.If aux. Boiler in service then this condensate is diverted to its de-aerator tank.To blow down basin.

Q.8.12: - How you will supply Steam converter secondary steam to an otherunit and recover its condensate?

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We can supply secondary steam to other unit by opening tie valve between two units,located in HFO tank area and in the same way condensate recovery tie valve will beopened.

GENERAL 9

Q.9.1: - Write down the isolation procedure of Boiler local gauge glass forrepair job? How many local gauge glass at our Boiler?

Repair job procedure of boiler local gauge glass:Balancing line to down comer-isolating valve should be closed.Close waterside isolating valve.Close steam side isolating valves.Open drain valve.

Boiler gauge glasses:

2 on steam drum.2 on steam air heaters condensate cooler, one on each other.3 on steam converter.

1 on condensate tank.1 on converter1 on converter cooler.1 gauge glass on AUX. Boiler.1 on boiler drum(Monometer gauge on feed tank)

Q.9.2: - How you will take Boiler local level gauge glass in service?

Procedure: Open drain valve.

Crack open steam valve for 3 to 4 hours so gauge glass will warm upClose drain valve after heatingOpen steam and waterside valve simultaneously.Adjust the flow through balancing line so we can see the waterdropping in gauge glass.

Q.9.3: -What is the function of a safety valve? How a spring-loaded safety valveworks, what will be your action if a safety valve start continuously popping?

Safety valve is a device, which saves the vessel or line against over pressurizing. Ifdue to any reason pressure increase from certain safety limit, then safety valve will liftand it will release all the excessive pressure.

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Spring loaded safety valve is adjusted by its spring tension and when the line orvessel gets over pressure then it lifts its spring and releases the pressure.If safety valve starts continuously popping then first we will investigate the reason ofover pressure. And try to make it normal. If pressure is normal and safety valve is stillpopping then it means that safety valve is stuck we will try to reset the safety valve by

its pop off lever, if still pooping on then we will decrease system pressure and we willcall Mechanical Engineers.

Q.9.4: - Write the indication of tube leakage at super heater and re-heatersection, also describe your action?

Indications of a super heater tube leak.

More make up water will be consumed in the cycle.Abnormal sound will be at local location.Furnace pressure will be high then normal.

Flue gases opposite will become high and white smoke will come out ofstack.Gas air heater flue gas temp will be high.Gas air heater differential pressure will become high.

Following indications come in case of reheat tube leak.

Abnormal sound at local.More made up water will be used.

Flue gases opacity will become high and white smoke will comeout of stack.Furnace pressure will be high.Boiler feed water flow will increase.Main steam flow will increase.Gas air heater differential pressure will be high.Gas air heater flue gas temp will be high.

Q.9.5: - What is the source of aspirating air? Where it is being used also writethe purpose of this air?

Service air is the source of aspirating air and we use this air when any maintenance

job is required on peep hole, furnace doors, soot blowers, TV camera or burner guns.We have pressurized furnace boiler and the function of this air is to stop the hotgasses and fire to come out from the furnace.

Q.9.6: - Describe the cold start up of boiler also differentiate between hot start,warm start and cold start?

Preparations for Cold start up of boiler:.

Fuel oil system.

Verify that HFO tank bottom heater is in service and its TCV set pointadjusted at 50oC.

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Verify that HFO pump suction heater is in service and its TCV is on auto andits temp. Set point is 68oC.

Verify that instrument air supply is available for HFO p/p, DO pump andigniter oil pump PCVs.Tracing steam supply to HFO transfer pump should be line up.

Before HFO transfer pump starting open three turns of HFO PCV bypassvalve.Verify that HFO and DO storage tanks levels are more then 4 meters.Verify that fuel oil isolating valve of burners and igniter are closed.Start Igniter oil and diesel oil pump and Header pressure should be 10 bar.

Air and gas system.

Verify that BCW is available and its bearing oil temp is not morethen 35oC.Verify that bearing oil level is normal and its cooling water inlet and out

let valves are open.Verify that instrument air supply is available for dampers control.

Boiler circulating pump.

Verify that BCP cooling water flow is more then 11m3 and its temp is notmore then 35oC.Verify that steam drum level is 150mm high then its normal level.BCP motor cavity temp is less then 50oC and is properly vented.

Boiler startup.

Open root valves of CBD, super heaters and de-super heaters.All the vents of economizer, super heaters, SCW should be open at thetime of start up.Start the air and gas system and verify that discharge dampers of GRFand FDF are open.After starting the FDF and GRF their bearing oil temps should notincrease more then 75oC.More over AC cooling fan and igniter fan temp should not increasingmore then 70oC.

Open vent valve of DO, Igniter oil and HFO ring headers and close themafter venting.Now furnace purge start command will be execute and leak test and furnace purgewill start simultaneously. Leak test will be completed after three minutes and returnMOV of fuel shut off, igniter oil diesel oil and HFO will be open. Furnace purgewill be completed in 5 minutes. After completion of furnace purge and leak test MFT relay will

automatically reset.Open A-elevation burners, igniter, atomizing steam and atomizing air shutoff valves.

Fire A1 and A3 igniter and burners. When steam drum pressure reaches up to 2 bars then close all the vents

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of steam drum, SH, SCW and economizer.Open drain valve of Aux. Steam from 3ry SH inlet header side.When main steam pressure reaches at 20 bars then open aux steamMOV about 15% to warm up the system and make it full open after sometime.

When Aux steam PCV control 15-bar pressure close aux steam tie valveand also close its drain valve.Vacuums process of condenser will be started now.Take steam air heater in service and initially open its TCV 25% for warming.When condenser vacuum reaches at 630-mmHg open turbine HP turbine by-pass valve and control the temp and pressure of main steam before that itstemp and pressure was being controlled by 1ry, 2ry 3ry SH drain valves.Now fire Igniters and burners A2 and A4.Now re-set the turbine.Start turbine rolling when steam conditions are satisfied.Synchronize the Unit when turbine speed reaches at 3000 RPM.

Fire B1 and B3 burners.Close the steam trap bypass valve of SAH heating lines, Aux steamheaderand atomizing steam lines.

Start fire mag dozing pump.Close SH drain root valve.Shut down the DO burners and fire HFO burners.After chemistry check convert the steam convert primary condensate to LP2heater.

When boiler master is on auto and HP turbine bypass is closed then control the mainsteam pressure and start load increasing and fire now B2 and B4 burners byselecting the unit on CO mode.Stoppage period tells us the difference between hot start, Cold start and Warmstart.

Hot start up means that unit remained in stopped position less than 8 hrs

Warm start up means that unit remained in stopped position more than 8 hrs butless than 150 hrs.

Cold start up means that unit remained in stopped position more than 150 hrs.

Q.9.7: - What will be your action at black out when

(a) Aux. Boiler in service

(b) Main Boiler at hot banking.

(c) Main boiler in service

If power fail occurs when Aux boiler is in service and main boiler is on hotbank.

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Switch off its diesel oil pump and feed pump.Close its root valve of steam line.Check the diesel generator is in service or not...Make sure that all fuel valve of main boiler are closed.If compressor is not running then open tie valve from other in

service unit.Air heaters should be driven by DG or air motor, If air motor is not running then

air heater should be driven manually by lever.Check that DC cooling and sealing air fan is running.GRF turning gear motor should run on EDG.Normalize the service water system for BCP coolers so that BCP cavitytemp. Cannot increase more then 52oC.Open all drain and bypass valves of steam traps of aux, atomizing andheating steam.

Q.9.8: - What you know about Run back which equipment belonging to boilermay be the cause of run back?

Due to problem in any Aux equipment if generator load is coming down rapidly, so itwill be called Run back.Following conditions or equipment can cause a Run Back.

One CWP trip and stand by pump not cut in.One condensate pump tripped and standby pump not cut in.From two one HFO pump tripped and stand pump not cut in.One BCP trippedOne FDF tripped.One gas air heater trippedAPC limit if fails

Q.9.9: - Explain the procedure of rack out and rack in of HT motor breaker?

Rack out of HT motor breaker:Open the breaker of the running equipment, and inform to CCR for the rackingout of the HT breaker.Turn off aux. Supply switch of the HT breaker.Press trip push button and insert the lever.

Then turn the lever in anti clock wise direction to Rack out the HT motorbreaker.When Disconnected display appears then the breaker is racked out. Informto CCR.

Rack in of HT motor breaker:Inform to CCR for the Racking in of HT motor breaker.Check that aux. Supply switch of the HT motor breaker is in off condition.Press trip push button and insert the manual lever.Turn the manual lever in clock wise direction to Rack in the HT motorbreaker.

When Connected display appears then the breaker is racked in. Inform toCCR.

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Q.9.10: - When & How you will flush Vanadium Inhibitor dosing pumps andlines, why it is important?

Open the supply line valves from the diesel oil tank.

Close the supply line valves from the fire mag tank.Increase the strokes of fire mag pumps, for the flushing of lines.Continue this for half hour.

Q.9.11: - How to unload Vanadium Inhibitor from drums to dosing tank?

Drain any condensation from pump air supply line.Checks lube oil level.Insert suction line of pump into the drum and open suction valve and pumpdischarge is in fire mag storage tank.

Give some stroke to pump, up to 2-3bar pressure, to avoid cavitations.Then start pump to add fire mag into the storage tank.

Q.9.12: - Black smoke is coming out from boiler stack, what you have to checkto correct the combustion?

Check all the burner flames locally.Check fuel oil temperature from burner header.Check atomizing steam pressure.Check O2 analyzer reading, if it is less ask control room to raise it.

Q.9.13: - What is the function of S.H out let electromatic PCV, How does itoperates?

It is electromatic power operated safety valve. Its function is to release the excessivepressure of main steam line/3ry super heater out let.It is supplied with 110DC source which is more reliable in all operating conditions,when ever pressure goes high, more then a given set point it will operate and releasethe excessive pressure from the system to prevent SH.

Q.9.14: - There is a considerable amount of steam is coming out from BBD tankstack. State your actions to minimize the wastage of steam?

In this case we have to check the all drains care fully, also check the turbine areadrains, steam traps passing could be a cause also the bypass valves of steam trapsshould be check. By these checks we can control the wastage of steam.

Q.9.15: - In case of hammering in a line what will be your action?

Check any condensate in that line by partially opening its drain valve, also try toreduce the flow of fluid from supply source and warm the line properly. When line

condensate is removed and line is warmed up then open its supply valve slowly.

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Q.9.16: - What equipments are provided with cooling water system?

GRF bearing, FDF bearing, FDF motor winding, Air heaters guide bearing lube oilcooler and BCP coolers.

Q.9.17: - What is the purpose of soot blowing, what will your action if a sootblower tripped? Write the locations of soot blowers?

The purpose of soot blowing is to maintain the heating surface clean and toprevent plugging of the gas passage.

Soot blowing removes the soot from super heater and re-heater tubes and gas airheater element with the help of superheated steam in ordered to increase the heat

transfer rate because soot particles make a layer on boiler tubes and due to thatproper heart transfer will not take place. To remove these layers from boilers asuperheated steam from 3ry SH inlet header is used.

We have two Rotary soot blowers for gas air heater and 8 longitudinal soot blowersfor super heater and 8 longitudinal soot blowers for re-heaters.

If soot blower motor has tripped and soot blower is in advanced position so we willretract the soot blower manually by keeping steam flow open till that removal of sootblower get complete.

Q.9.18: -Which lube oils are commonly being used at boiler area, mention theequipments also.

FDF & GRF we use T-42Air heater guide bearing we use Alfa 460

OUTAGE ACTIVITIES 10

Q.10.1: - What you understand about Forced cooling, what precautions shouldbe taken during forced cooling and boiler water draining?

During outage or for some maintenance job in vessel we need to force cool theboiler. It means to reduce the metal temp of boiler tubes and also surface up to

working conditions by force.

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Following things are required to keep in mind during forced cooling and boilerdraining.

BCP will remain in service.Both GRF will be in stop position.The entire fuel-isolating valve should be closed.

FDF and gas air heaters will remain in service. Sealing and cooling fan will remain in service.

FDF in let guide vanes will be regulated in that way that the metal temp droprate of boiler should not exceed more then 100oC.The opening of primary and secondary super heater drains can control super

heatermetal temp drop rate.Stop first BCP at 70 bar pressure and second at 20-bar pressure.Open all the vents, which are located on rooftop and drum vents, whenpressure reaches at 2bar.When drum metal temp reaches to 90oC or air heater gas inlet temp is

Less than 150oC, stop air and gas system.Drain the boiler water by opening water drum drain when the boiler watertemp is 90oC, open drain of boiler walls, BCP discharge line and economizer.Normally we do feed and bleed during air and gas cycle on.

Q.10.2: - What are the routine checks related furnace and boiler pressure partsduring outage?

Check the soot deposits on up risers & down comer also,refrectary , check thepitting , thickness of the material,burners, there swerlers, burner tilt, air registers ,dampers,super heater tubes,vibration arresters, also check the same in reheatersection and check the Air heaters in washing is required do it and if the elementsneed replacement do accordingly.

Q.10.3: - Write the economizer and main steam cycle hydro test procedurealong with complete tag out?

Economizer and main steam cycle hydro test procedure:

First check main steam lines hangers and locked.Check economizer spool piece installed or not.

Check all vents i.e. (SCW, SH, Steam drum, economizer and main steam line)should be in open positionStart both Demi. water pumps and check that economizer drain valves,water drum drain valves and BCP discharge line drain valves should beclosed.Open economizer filling line valves locating near condensate tank.Now slowly open the economizer filling line valves on fifth floor.Open hydrazine injection line valve to economizer filling line valve.When air free water starts coming from the vents close all them step-by-step.Close economizer filling line valve, remove its spool piece andclose hydrazine injection valve.

Now start BFP and increase the pressure@ 2kg/cm2 per minute bydischarge MOV bypass valve.

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Raise boiler pressure up to required recommended pressure and hold it.Check any leak inside the boiler if there is no leakage then releasethe pressure and drain the boiler up to required level.

Economizer and boiler tag out list.

Sr.#

Description KKS# Tag/lock

Position

1 SP lower header drain valve (left &right)

Tag Close

2 1ry super-heater drain valve (L&R) Tag Close

3 CBD root valve. Tag Close

4 3ry SH drain valve (L&R) Tag Close

5 2ry SH drain valve (L&R) Tag Close

6 4 water valve of water drum Tag Close

7 SH spray water line drain valve

(L&R)

Tag Close

8 SH spray water-isolating valve(L&R)

Tag Close

9 Economizer drain valve. Tag Close

10 AUX .Steam 3ry SH side MOV handwheel.

Tag Close

11 AUX .Steam 3ry SH side MOVbreaker.

Tag Off

12 Hydrazine injection line valve. Tag Close

13 Economizer sampling line valve. Tag Close

14 Phosphate isolating valve (L&R) Tag Close

15 Main steam sampling line valve Tag Close

16 Drum sampling line valve Tag Close

17 BCP A casing drain valve Tag Close

18 BCP B casing drain valve Tag Close

19 Soot blowing MOV hand wheel Tag Close

20 Soot blowing MOV breaker Tag Off

21 Main steam PCV manual isolatingvalve

Tag Close

22 Main steam PCV power suppliesbreaker

Tag Off

23 8-drum level TX impulse lineisolating valves

Tag Close

24 HP bypass isolating valve Tag Close

25 HP bypass isolating valveequalizing valve

Tag Close

26 Main steam line drain MOV breaker Tag Off

27 Main steam line drain MOV handwheel.

Tag Close

28 1ry SH vent valve. Tag Close

29 Main steam li9ne vent valve after

3ry SH

Tag Close

30 Economizer vent valve (L&R) Tag Close

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31 SP out let header vent valve (L&R) Tag Close

32 Steam drum Common vent (L&R) Tag Close

33 Steam drum vent (L&R) Tag Close

34 SCW header vent valve (L&R) Tag Close

35 MSVs leak of line to be blind. Tag

36 Main steam line hangers pins tobe fixed.

Tag

37 Safety valves to be gagged Tag

38 Standard pressure gauge on drumto be installed.

Tag

39 Boiler air and gas system need tobe tag.

Tag

Q.10.4: - Describe reheat cycle hydro test, why it is necessary to remove thatwater after hydro test?

Re-heat hydro teat procedure:

All the super heaters should be drained.Check RH line drain valves are closed and re-heater spool piecehas been removed.

Open the re-heater vent valve.Blind the RSV and ICV leak off lines.Start re-heater filling through sealing water header and whenwater comes from the vents then close the vent valve.Raise the pressure of re-heater with the help of CP up to desire

value and hold it.Check the leakage in re-heater section.If there is no leakage then normalize.

Note:It is necessary to remove water from re-heater because it is super heated steam pathand if water will remain in the lines, it could enter in the turbine and could causehammering.

Q.10.5: - Explain air heater washing procedure?

Preparation:Confirm that AH gas inlet temperature is below 50C.Confirm that off-load AH wash water pump is available for service.Confirm that NaOH dosing pump for AH washing is ready.Confirm that unit drainage pit pumps are on auto mode.Confirm that neutralization and blow-down basin pumps are ready.Confirm that NaOH dosing pump for unit drainage pit is ready.

Remove the blind plates of following:FDF-A & B casing drain blind plates.GRF-A & B casing drain blind plates.

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Close AH air inlet/outlet dampers and AH gas inlet/outlet dampers.Open AH-A & B upper and lower manholes for the visual inspection.Confirm that there is no blind plate on following:

AH-A & B air inlet hopper drain line.AH-A & B gas outlet hopper drain line

Carry out water washing of AH wash water line by first loosing the nuts of the AHwash water inlet blind plates and then opening each individual isolation valve of thatline to proceed with the flushing activity one at a time. (With AH wash pump inservice).

Close all the isolations valves of AH wash water lines afterwhen flushing of these lines are completed.Prepare 100 liters of 45% NaOH solution in caustic soda tank.

AH-A &B water washing (High & low temperature side):

Start air heater air drive motor A & B and adjust the speed to 1/3 RPM.Crack open AH A & B high temperature side (upper) wash water isolating

valve, slowly open more until washing pressure reaches the 2 bars. At the same time,start injecting NaOH at the wash water inlet and adjust pump strokes until pH isbetween 9-10. Confirm that the unit drainage pit pump is running and that the pit isnot over flowing. Also start NaOH dosing to unit drainage pit.

Do the same as above for AH-A & B low temperature side water washing.Confirm that there is no overflowing at unit drainage pit.

Record the time, pH of inlet wash water, and pH of drain water line.Close high & low temperature side isolating valves when washing is

completed.

NOTE: If the pH difference between washing water and the drain sample is between1-2, stop AH washing.

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