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Station: NTPC- Simhadri BHEL Ref No. PS-DC-186-500-0002

NTPC Ref no SIM /1/CS/1/005Sheet 1 of 40

Plant area: BOILER

Testing / Commissioning Schedule: BOILER ALAKALI BOIL OUT AND ACID CLEANING

SLNO

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

LIST OF CONTENTS

PLANT DETAILS

TESTING OBJECTIVES

TESTING PROPOSALS

SERVICES REQUIRED

SAFETY PRECAUTIONS

EMERGENCY PROCEDURES

STATE OF THE PLANT

TEST METHOD

COMPLETION CRITERIA

APPENDICES

a) TECHNICAL SPECIFICATIONS

b) SAFETY CLEARANCE CERTIFICATE

c) MECHNICAL PLANT ITEAM COMPLETION LIST

d) ELECTRICAL AND C & I PLANT ITEM COMPLETION

LIST

e) DRAWING

f) LOG SHEETS.

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Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0002


Plant area: BOILER


SLNO

1.0 PLANT DETAIL

The steam Generator is a controlled circulation plus RadiantReheat (Type CC+RR) boiler. Firing equipment consists of fiveelevation of remotely controllable high energy arc Ignitors, fiveelevations of air cooled, non-retractable steam automising oil Gunand nine elevations of pulverized coal nozzles. The nineelevations of pulverized coal nozzles are supplied with coal fromnine numbers of type XRP 1003 Bowl mills, which form the loadcarrying fuel for the boiler.

Control equipment provided consists of furnace safeguardsupervisory system, scanner air control system and a secondaryair control system.

Major auxiliary equipment provided consiss of pulverizers,feeders, fans and miscelleneous valves. Three number of boilercirculating pumps are provided to ensure proper circulation ofwater in the furnace wall circuits.

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Plant area: BOILER


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2.0

2.1

OBJECTIVE

The objective of this commissioning schedule is to clean theinternal surface of the steam generating portion and heatingsurface (Economister) using specified chemicals.

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Plant area: BOILER


SLNO

3.0

3.1

3.2

3.3

TESTING PROPOSAL

The objectives are achieved by carrying out the following testingproposals.

By carrying out an effective boil-out, grease and any protectivecoatings applied are removed.

Then, it is subjected to acid cleaning for the removal of patchy

mill scale and rust.

Finally, the acid pickled surface is passivated for the formation ofuniform and coherent magnetite layer.

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Plant area: BOILER


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4.0

4.0.1

4.0.2

1.

2.

3.

4.

5.

SERVICES REQUIRED.

Prior to the commencement of chemical cleaning, all thedemineralised water storage tanks should be kept full and thedemineralising units kept in regenerated condition.

Approximately, 6000 m3 of demineralised water will be consumedfor the entire process. At any time of acid cleaning, a minimum oftwo boiler volumes (app. 1400 m3 ) of demineralised water shouldbe available in ready stock to facilitate rapid flushing of thesystem in the event of chemistry upset.

All the required quantities of chemicals as given below should bemade available prior to the commencement of the process.

SPECIFICATION OF CHEMICALS & QUANTITY

NAME OF CHEMICALS QTY/Each Boiler

Na2

HPO4 12 H

2O DISODIUM

PHOSPHATE 800 Kg.1S 566 1991

Na3PO

412 H

2O TRISODIUM PHOSPHATE 1500 Kg.

IS:573:1992

HYDROCHLORIC ACID : 30% MIN 70 Tonnes.IS:265:1993

RODINE : 213 SPECIAL(PROPRIETORY ITEM) 800 Ltrs.

Mfd. by Agromore, Bangalore

CITRIC ACID 800 Kgs.IS:5464:1991

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Plant area: BOILER


SLNO6.

7.

8.

9.

10.

11.

12.

4.0.3

4.0.4

4.0.5

4.0.6

4.07

4.08

4.09

4.10

4.11

AMMONIA : 25% 600 Ltrs.

IS: 799-1990

HYDRAZINE HYDRATE: 80% 750 LtrsIS:12086 1992

NITROGEN CYLINDERS: 6.2 mm3 each 500 Nos.IS:1747:1991

AMMONIUM BIFLUORIDE ; 97% 1000 kg.IS:13119 1991

HYDRATED LIME : Grade A 05 Tonnes.IS:1540:1990 (Part II)

BLEACHING POWDER : Grade I 6 Tonnes.IS:1065 1989

CAUSTIC SODA (IS 252) 30 Tonnes.

For acid pickling, temporary polythene U tube should be used fordrum level.

6.6 KV, 415V Supply available.

220 AC/DC, 110V AC control supply available.

Instrument/service Air available.

Chemist/Express lab available

Auxiliary steam available. (Approx: 15 TPH at 12 kg/cm2 & 250deg C.

Boiler pressurising pump available for use

Boiler fill pump available for use.

Flood lights / telephones / walkie-talkie are available.

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Plant area: BOILER

Testing / Commissioning Schedule: BOILER ALAKALI BOIL OUT AND ACID CLEANINGSLNO

4.12

4.13

4.14

4.15

4.16

In the acid tank, only hydrochloric acid and inhibitor should bemixed. Ammonium bifluoride shall be prepared in the chemicaltank. Thiswill be mixed with the acid solution about a couple ofhours prior to the commencement of acid injection.

The drum internals are to be installed both in the upper and lowerdrum after acid cleaning.

Two independent sources of purge water is made available for

boiler circulating water pumps.

Efficiency test of Inhibitor shall be carried out before start of Acidcleaning activity.

Ambulance / car for emergency / fire tender available.

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Plant area: BOILER


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5.2.3

5.2.4

5.3

5.3.1

5.3.2

5.3.3

5.3.4

5.3.5

5.3.6

A suitable first aid treatment room with outside telephone facilitiesshall be provided within a reasonable distance of the place wherechemicals are being used.

A suitable room shall be provided for housing the protectiveclothing and apparatus required for emergency use.

FIRST AID TREATMENT

Splashes of the eye

Immediately flood the eye with water. To be effective the eyelidsmust be opened. The eyelids should be pushed apart using thethumb and index finger of the left hand. The casualty will probablynot be able to open the eye himself because of painful spasms.

If an eye wash bottle is used the jet should not be directed at thefront of the eye. It should be directed in from the side, so that flowis over the surface of the eye.

Irrigation should be continued for 5 10 minutes after which thecasualty should be taken to the first aid room.

Irrigation should be continued in the first aid room. Remembervision is saved by thorough irrigation, no other treatment canprevent damage if this is omitted.

After thorough irrigation the eye should be covered with a pad;the patient should be referred for medical opinion.

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5.4

5.5

5.6

5.7

5.8

Irritation of the skin

If signs of skin irritation occur the persons should be removedfrom contact and referred for medical opinion. In the event of thesplashing of the skin with chemicals the effected area should bewashed thoroughly avoiding spreading contamination to the faceand eyes.

Pipe Insulation

All temporary / Permanent pipelines carrying steam / hot water

and coming in contact with personal will be insulated.

Test area will be cordoned off and unauthorized persons entryshall be prohibited .Suitable signboard shall be displayed.

Whenever any inspection in made during the cleaning process,the location should be adequately ventilated.

SAFETY OF PLANT:

A) If the light up after cleaning could not be done within 3

weeks after completion of cleaning, the system will besuitably preserved.

B) Temperature limitation specified for various step shouldnot be exceeded in no case.

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Plant area: BOILERTesting / Commissioning Schedule: BOILER ALAKALI BOIL OUT AND ACID CLEANING

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6.0

6.1

6.2

6.3

6.4

EMERGENCY PROCEDURES :

The testing team should be aware of the operating procedures offire extinguishers to be used for quenching minor or major fires.

The testing team should be aware of the procedure to be followedin case of accident involving personnel injury .

In case of failure of running circulating pump the stand by pumpshould be started immediately without delay.

A person is to be posted at emergency push button andinstructed closely that he should trip the pumps in the event ofemergency being notified to him by observers.

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Plant area: BOILER


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7.0

7.01

7.02

7.03

7.04

7.05

7.06

7.07

7.08

STATE OF THE PLANT

During the acid cleaning process, all the permanent boilerinstruments are isolated except providing a temporary pressuregauge of 0 to 5 kg/ cm2 in the drum for monitoring nitrogenpressure in the drum during nitrogen capping.

For alkali boilout, neutralizing and passivation processes,essential control and instruments viz. Protections, interlock,alarms, measurement, annunciation etc. required for safe lightupof boiler are made available, as per mutually agreed list between

site NTPC and BHEL.

Boiler is flushed thoroughly including the temporary pipe linesand system. This should be done prior to the connection oftemporary acid cleaning system to the main boiler.

For chemical cleaning process, the internals of the non-returnvalve provided in the economiser recirculation line is removed inorder to facilitate fast filling and draining of the boiler.

All the boiler auxiliaries are made ready and available for boiler

light up. This includes Auxiliary steam, chemical dozing pumps,tanks, boiler circulating pumps, fans, oil pumps etc.

Drum vent lines, Nitrogen capping lines are properly tagged andtaken to suitable location for easy operation.

Prior to the commencement of alkali boilout, alkali flushing(detergent flushing) of preboiler system is completed.

Drum internals including primary and secondary separators,orifices at the bottom drum are to be installed after the chemical

cleaning process. The baffle plates inside the bottom drums areto be installed before the alkali boil out.

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Plant area: BOILER


SLNO7.09

7.10

7.11

7.12

7.13

7.14

7.15

7.16

7.17

In addition to the metal temperature in the drum, additional

temperature points with peening type temporary thermocoupleare provided in the ring header (bottom drum) at minimum 4locations at equal distances. Provision made for monitoringtemperature in the control room.

O & M instruction for the boiler and other auxiliaries includingcirculating pumps are available well in advance of thecommencement of the cleaning process.

The pressure and temperature gauges and the flowmeterinstalled as per the scheme.

All the safety measures discussed and implemented in advancewith suitable instruction/caution tags provided at strategic places/equipment.

Various drainings from the system at different operations duringthe process is provisioned with adequate neutralisation prior tofinal disposal.

Boiler tube coupons placed at two ends inside the drum andbottom ring beader to see the effectiveness of the cleaning.

Proper neutralising arrangement is available at site to neutralizeand dispose off the effluent in line with A.P. pollution controlboard norms.

Chemical dosing system is ready in all respect.

MD-BFP is available for regular operation.

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Plant area: BOILER


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8.0

8.1

8.1.1

8.1.2

8.1.3

8.1.4

TEST METHOD :

ALKALI BOIL OUT

The boiler (steam generating surfaces and economiser) is filledwith an alkaline solution containing 500 ppm of disodiumphosphate dodeca hydrate, and 1000 ppm of Tri sodiumphosphate do deca hydrate and then fired to raise the pressure to40 kg/ cm2, following the specified operational procedures. Duringthe process, rotation of boiler circulating water pumps should bedone as per operating instructions.

ProcedurePrepare the boil out chemical solution in hot demineralised waterin the chemical mixing tank. The solution is formulated bydissolving the following proportionate quantities of chemicals,depending on the volume of the system to be cleaned.

1. 0.05% Na2 HPO4 12 H2O

2. 0.1 % Na3 PO4 12 H2O

Hold the solution prepared as above in the tank and homogenisethe same by recirculating the solution by operating chemicalinjecting pumps.

Start filling the boiler with demineralised water, with simultaneousblend filling of already prepared boil out chemical solution.

Light up the boiler as per O & M instructions and gradually raisethe pressure to 40 kg/ cm2 . Hold the pressure for four hours.Obtain boiler water sample from CBD sampling point and analysefor alkalinity, phosphate content, dissolved silica and oil content.Prescribe blow down every 2 Hrs. once, after killing the fire;Duration the blow doum shall be for one minute Ensure that thedrum level does not go out of gauge glass vision. Repeat theoperation of raising the pressure to 40 kg/ cm2 .

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Plant area: BOILER


8.1.5

8.1.6

8.2

8.2.1

8.2.2

8.2.3

collecting sample for analysis and prescribing blowdown till oilcontent is no longer detected in the sample analysed. During theprocess if the phosphate concentraction drops to half of the initialvalues maintained, dose additional chemicals through phosphatedosing system to restore original concentration.

NOTE: All the testing will be done as per the mutually agreedstandard procedure.

The boil out is declared completed when the oil value is no longerdetected or minimum eight blow downs are completed whicheveris later.

Drain the boiler, when it is cooled, as per O & M instructions.Once the draining is completed, fill the boiler with demineralisedwater, heated to 80 deg C, through boiler fill pump. Back flush thesuperheaters with DM water containing 200 ppm hydrazine andpH 10.0 with NH

3till it overflows into the drum. Drain the boiler to

the waste disposal system. Inspect the lower and upper drum.Manually clean them.

NOTE

To speedup economiser filling and draining operation, theisolating valve in the economiser recirculation line is to be keptopened and the internals are to be removed from the non-returnvalve provided in the economiser recirculation line.

As far as possible, all the boiler circulating pumps should be keptrunning on rotation during alkali boil out. However, if due to anyunforeseen reasons, any of the pumps remains out of service, the

non-running pumps are also to be kept under continuouspurging.

Drum internals (both primary and secondary separators) need notbe installed in the upper drum.

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Plant area: BOILER


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8.2.4

8.3.0

8.4.0

8.4.1

8.4.2

8.4.3

8.4.4

Orifices in the lower drum will not be installed for alkali boil out aswell as for acid cleaning operation, to be followed. However,baffle plates are to be installed in the lower drum for both alkaliboil out and acid cleaning.

Whenever, boiler is to be filled with chemical solution and if theprocedure calls for boiler light up, the following guide lines shouldbe followed besides O & M instructions.

FILLING UP OPERATION:The chemical solution should be filled up parallely through the

bottom drum and economiser till the water level is seen at thelower most portion of the level gauge.

LIGHTING UP

Besides following the O & M instructions the following points areto be taken care of.

Drum air vents are to be opened before lighting up the boiler.

The drum level has to be brought to the top port of the gauge

glass. This would provide the necessary water for filling theheaders and tubing above the normal water level.

Start the boiler circulating pumps in accordance with the boilercirculating pump operating instructions.

After commissioning two pumps, take out or add water toestablish 100mm above normal level indicated in the gaugeglass.

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SLNO8.4.5

8.4.6

8.5

8.5.1

8.5.2

8.5.3

8.5.4

8.5.5

8.5.6

Initiate boiler light up as per O & M instructions.

Place further boiler water circulating pumps in operation when thedrum pressure reaches 5 to 7 kg/ cm2 and gradually bring thedrum level to normal level as the pressure increases. Pumpsshould not be started during rapid boiler temperature changes.(More than 100 deg C / per hour).SHUTTING DOWN

At about 7 kg/ cm2 drum pressure, remove fire from the unit,maintaining drum level 100 mm above the normal level indicated

in the gauge glass.

Remove first and second boiler circulating pumps from service at5/7 kg/ cm2 .

Keep at least one pump running at drum presures below 2kg/ cm2

And bring the water level to normal.

Open drum vent when the drum temperature is around 90 deg Cto 100 deg C.

Bring the water level in the drum to the lower most visible point inthe gauge glass and stop the last boiler water circulating pump.

Drain the unit after attaining the desired cooling at the downcomer and suction manifold.

By following the above procedure, pump vibrations aremaintained and air ingress also averted.

Chemical feeding pumps and boiler fill pumps should be startedsimultaneously achieve feeding of chemicals at a controlled and

uniform concentration. Boiler filling should be done through water

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8.6

8.6.1

8.6.2

8.6.3

walls and economiser simultaneously. Uniform and required

concentration can be obtained by throttling respective controlvalves.

ACID CLEANING

Acid cleaning is carried out by adopting soaking technique, usinghydrochloric acid of 5% + 1%, 0.2% V/V Rodine 213 Spl. And0.25% ammonium bi-fluoride. Pickling by acid is followed by plaindemineralised water rinse, ammoniated citric rinse (0.2%), plaindemineralised water rinse and neutralisation of the pickledsurfaces with a mild alkaline soulution containing a mixture of di

and tri sodium phosphate. Finally, the entire cleaned andneutralised surfaces are passivated with ammoniated hydrazined solution at an elevated temperature and pressure. Allthe draining operations prior to the neutralisation step are to bedone under nitrogen capping. The gauge glass used for alkali boilout is to be replaced by a U tube manometer.

MOCK TRIAL:

A mock trial should be conducted prior to the commencement ofthe pickling operation to check the healthiness of the temporary

system erected and to acquire an idea of operations of variousvalves, pumps and other connected system, so that actualoperation is carried out to the nearest accuracy. The boiler fillinfin approximately 1 hour and draining in approxmately 1 hour areto be achieved.PROCEDURE:

Back fill the superheaters with demineralised water containing amin. of 200 ppm hydrazine with solution PH raised to 10.0 usingammonia. Having ensured that the superheaters are filled, fill the

boiler parallely through water wall and economizer with plaindemineralised water upto the normal operating water level. Lightup the boiler as per the O&M instructions and raise the metaltemperature both at the drum and suction manifold to 80 deg. C

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8.6.3

8.6.4

8.6.5

8.6.6

8.6.7

with boiler circulating pumps in service. Once the temperature isreached, shut down the pumps and drain water from boiler to thewaste disposal system. Close all the furnace openings to retainthe heat in the boiler.

Mix the required quantities of 30 32% Hydrochloric acid andRodine 213 speical, inhibitor and keep it ready in the acid tanks(2 Nos.). Dissolve required quantity of ammonium bi-fluoride inD.M water and keep it ready in the chemical mixing tank. Transferthe ammonium bi-fluoride solution into the acid tank. Thoroughly

mix the inhibited acid and transferred ammonium bifluoridesolution by running the chemical injection pump on recirculationfor a minimum of one hour, particularly prior to thecommencement of chemical injection into the boiler.

Keep all the boiler blow down valves shut and drum vent valvesopen to facilitate escape of gases generated during picklingprocess.

Keep the nitrogen capping system ready prior to thecommencement of acid filling.

Choose the centrally located boiler circulating pump for operationto circulate the chemical solution during soaking/pickling time.Keep a continuous supply of purge water to all the boilercirculating pumps.

Start filling the boiler parallely through water wall and economiserwith heated demineralised water restricted to 65 deg C 70 degC. Simultaneously start injecting the chemical solution alreadykept prepared in the acid tanks (mixture of inhibited hydrochloricacid and ammonium bifluoride) along with the fill water. Suitably

control the opening of the control valves to achieve a uniformconcentration of 5% + 1% acid concentration in the water beingfilled in the boiler. The regulation of uniform acid concentration isdone by very frequent sampling, testing and suitable adjustment

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8.6.8

8.6.9

of the opening of the chemical injection control valve. The

temperature of the chemical mixed water should in no case andat any point of time exceed 65 to 70 deg. C. Stop filling throughsuction header of Boiler circulating pump. When the level in thedrum is at the bottom of the gauge glass. But continue fillingthrough the bottom drum and economiser till the level in the drumtouches 100 mm above the centre line of the gauge glass. Thiswill ensure complete filling of ECO links to the drum and thewater wall riser tubes. Do not permit the level to go out of sight inthe gauge glass. Once the filling is completed, start the selectedboiler circulating pump. Immediately collect sample of the filledsolution from the boiler after the start of the circulating pump.

Subject the sample to analysis for evaluating acid strength andtotal iron concentration.

The boiler circulating pump will be operated for 30 mts. At thisstage collect sample at every 5 mts. Interval and analyse for acidstrength and iron concentration. At the end of 30 mts. period stopthe pump and allow the chemical solution to soak. Continuesample collection and chemical analysis for acid strength and ironconcentration till three samples show equilibrium status. If theacid strength and the iron concentration values do not level outand attain equilibrium status, operate the same boiler circulating

pump that was in service earlier for 5 mts. at an interval of 30mets. Regardless of analytical results, the total acid contact timewill not be allowed to exceed 6 Hrs. including the time for fillingand draining.

Declare the completion of pickling process once the acid strengthand iron concentration level out and reach equilibrium. Now,operate the same Boiler circulating pump, that remained inservice earlier for 5mts. Stop the pump and drain the unit underNitrogen Capping, maintaining the nitrogen pressure in the drumaround 0.5 to 1 kg/ cm2 . Drain the boiler as fast as possible,

maintaining the nitrogen pressure, to waste disposal system.

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8.7

8.7.1

8.8

8.8.1

8.8.2

8.8.3

DM RINSE

Re-fill the boiler by running the boiler fill pump with demineralisedwater heated to a temperature of 60 deg C 65 deg C takingcare of the operation of the drum vent valves to maintain 0.5 kg/cm2 . Nitrogen pressure in the drum. Fill the water to the centre ofthe gauge glass. Now raise the level in the drum by 100 mm, byback flushing the superheaters. This will also remove, if any traceof acid vapours lodged in the connecting links to thesuperheaters. Now run the boiler water circulating pump, that wasoperated earlier for 5 mts. Drain the boiler under Nitrogen

Capping as practised earlier. Once the feed links, water walls andeconomiser draining is completed, close the drain valves andretain Nitrogen atmosphere in the system.Ammoniated Citric Acid Rinse

Prepare a solution of citric acid with the required quantity of citricacid monohydrate and liquor ammonia in the chemical mixingtank. Keep the solution under recirculation to maintainhomogenity.

Start filling the boiler parallely through the Boiler circulating pumpsuction header, water wall and the economiser with hotdemineralised water restricted to a temperature of 60 to 65 deg .C. Simultaneously start injecting ammoniated citric acid solution.

Maintain a uniform uniform strength of 0.2% acid in the watertaken into the boiler. Adjust the PH. of the final solution enteringthe boiler between 3.5 and 4.0. Continue the filling operation, tillthe level in the upper drum is close to the bottom of the gaugeglass. Raise the level in the drum by another 30 to 40 mm byfilling through the economiser by closing the valve in boiler

circulating pump suction header and continue filling throughbottom drum and economiser so as to fill economiser and waterwall connecting links. Further bring up the level in the drum to +100 mm by back flushing the superheaters.

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8.8.4

8.9

8.9.1

8.9.2

8.10

8.10.1

Start the same boiler water circulating pump that remained inoperation earlier, run it for 5 mts. and shut it down. Collect thesample from CBD sampling provision and check for acid % andiron concentration. When lron concentration attain a steady statevalue for 2 consecutive readings declare citric acid rinsing iscompleted. In any case it will not be completed in less than 4 Hrs.or more than 5 Hrs. Close the drum vents and establish nitrogensupply. Drain the boiler under a positive nitrogen pressure aspractised earlier.

DEMINERALISED WATER RINSE

After draining the citric acid solution, fill the boiler withdemineralised water heated to 60 deg 65 deg C. Raise the levelin the drum upto + 100 mm mark. Operate the boiler watercirculating pump for 5 mts. Stop the pump and drain the boilerunder nitrogen capping as practised earlier. Repeat the filling andthe dumping operation under Nitrogen Capping till the ironcontent in the sample collected is less than 50 ppm. It ispreferable to lower the iron value to less than 25 ppm.

Maintain the nitrogen pressure of 0.5 to 1 kg/ cm2 and maintainthe nitrogen atmosphere in the system till the next process ofneutralisation is started.

NEUTRALISATION

This process is employed to neutralise any acid/acidic pocketremaining in the system and also to mildly passivate the acidpickled surface. This prepares the base for achieving an effectivefinal passivation. For this process, the boiler system and the

necessary instrumentation should be made ready to make firingfeasible. The U tube manometer provided for the acid pickling inthe drum should be replaced by the gauge glass used for alkaliboil out. All the boiler water circulating pumps should be madeready for operation.

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SLNO8.10.2

8.10.3

8.10.4

8.11

8.11.1

8.11.2

8.11.3

Prepare the neutralising solution in the chemical mixing tank with

approximate quantities of di-sodium phosphate do-deca hydrateand tri-sodium phosphate do=deca hydrate to get a concentrationof 0.1% and 0.2% respectively in the boiler. Recirculate thesolution in the tank to homogenise the mixture.

Start filling the boiler with demineralised water, with simultaneousinjection of phosphate solution, maintaining uniform concentrationthroughout the filing period. Keep the drum vents open whilefilling. The boiler filling is to be done as practised earlier. Start theboiler water circulating pumps as per the O & M instructions. Firethe boiler and gradually raise the pressure to 10kg/ cm2 . Follow

the precautions as detailed out for alkali boil out. Hold thepressure at 10 kg/ cm2 for about 4 hrs. Utilise this opportunity toblow off all the instrument lines that might have come into contactduring acid pickling time, for better neutralisation of those lines.

After 4 hours, kill the fire, allow the boiler to cool and drain theboiler as per procedure explained earlier and O & M instructions.While draining backflush the superheaters with demineralisedwater conditioned with hydrazine and ammonia. The boiler isdrained with the drum vents open to the atmosphere. Allow thesystem to aerate. Prepare the boiler for passivation.

PASSIVATION

The underlined idea is to form a protective magnetite coating onthe steam generating and water touched surfaces that wereexposed to the picking process.

Prepare a blended solution of hydrazine and ammonia withcalculated quantities in the chemical mixing tank in order to finallyachieve a minimum residual amount of 200 ppm hydrazine and asolution PH. of 10.0 when filled in the boiler.

Fill the boiler with demineralised water, with simultaneousinjection of hydrazine ammonia mixture. Fill the boiler throughbottom and economiser parellely as practised earlier, upto theoperating level in the drum gauge glass.

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Plant area: BOILER


SLNO8.11.4

8.11.5

8.11.6

8.11.7

8.12

8.12.1

Prepare the boiler for firing as per O&M instructions. Start theboiler water circulating pumps as per O & M instructions and firethe boiler at a slow rate. Raise the drum pressure to 40 kg/ cm 2

and hold it for 24 hrs and maintain a residual hydrazine content of25 ppm & a solution PH. 10.0 in the feed water being fed into theboiler during the entire passivation operation. Dose, hydrazine ammonia mixture in the feed water at the suction point of feedpump through L.P dosing system.

After 24 hours of operation, shut down the boiler and allow it to

cool slowly. Keep the boiler water circulating pumps in service asper the O&M instructions. Shut down the pumps when the metaltemperature drops to 95 deg C. Back flush the superheaters withconditioned demineralised water till the drum level raises by 25-30 mm.

Drain the boiler under atmospheric pressure and aerate thesystem.

Open the upper and lower drums for inspection. Manually cleanthem. Refit the drum internals and restore the boiler and prepare

it for regular operation for steam blowing, safety valve floatingetc.

NEUTRALISATION OF EFFLUENTS

Effluents generated during following activities will be neutralisedand disposed in line with A.P. Pollution control board norms.

Alkali Boil Out & Neutralisation of pickled surface:

PH of the solution is lowered to less than 9.0 by sufficient dilution

with raw / fire water.

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Plant area: BOILER


SLNO

8.12.2

8.12.3

8.12.4

8.12.5

Acid pickling

Effluent is neutralised with caustic soda. PH of disposed effluentbe maintained between 5.5 to 9.0 and fluoride less than 2.0 ppm.

Citric Rinse

Effluent is neutralised with caustic soda & bleaching powder. PHof disposed effluent to be maintained between 5.5 to 9.0.

Passivation

Hydrazine & Ammonia will be neutralised with bleaching powder.

The cleaning activity should be done with a planning that theboiler start up could be possible immediately after completion ofcleaning process.

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Plant area: BOILER


SLNO

9.0

9.1

9.2

9.3

COMPLETION CRITERIA:

The test coupons placed at identified locations will be taken out inthe presence of NTPC and all coupons will have uniformcleaning.

The drum surface will be visually inspected for uniform smoothcoating of magnetite.

The low point headers will be inspected and loose debris if any,

will be removed.

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Plant area: BOILER


10.0 APPENDICES :a) TECHNICAL SPECIFICATION

1. BOILER : Controlled circulation with Rifled Tubing. (cct),Radiant Raheat Dry Bottom, Top supported.

2. Furnace : Balanced draft Fumace with fusion weldedwaterwalls.

3. Volume of Furnace : 16424 m3

4. Fuel Heat Input : 1236.5 x 106 k cals / Hr

5. Super Heater : Stage I Type : LTSH Horizontal andpendant

: Stage II Type : SH division Panellette

: Stage III Type : SH finish Platen

6. Reheater (Type) : Radiant Front Platen Rear Pendant.

7) 100% BMCR Parameters :

a) SH/RH Flow : 1675 TPH / 1389 TPH

b) Pressure / Temp at SH O/L : 178 Kg/Cm2 / 540 deg C

c) Pressure /Temp at RH O/L : 43 Kg/Cm2 /540 deg C

d) Boiler outlet Temp (Gas) : 129 deg C

e) Efficiency Based on HHV : 87.11 %

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b) Safety Clearance Certificate

List of signatories required before running the system.

BHEL

1) Mechanical Erection

2) Commissioning

3) C & I

NTPC

1) Mechanical Erection

2) Mechanical ( O & M)

3) C & I (Erection)

4) C & I ( O & M)

5) Electrical ( O & M).

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C) Mechanical Plant Item Completion

i) Boiler erection completed and ready for Boiler light up andABO.

(Note: Air, Flue gas, Feedwater, Oil and steam streams required

for ABO to be finalised at Site mutually between BHEL & NTPC)

i) Auxiliaries required for ABO are erected and available foroperation.

ii) Temporary lay-out as per drawing given below at 10.0(e)required for Acid cleaning is completed and ready foroperation.

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SLNOd)

e)

, Electrical Plant Item Completion List.

List to be prepared jointly by BHEL and NTPC.

C & I Plant item completion list

List to be prepared jointly by BHEL and NTPC

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SLNO1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

11.

12.

13.

NOTE (Refer Drg.No. 4:PS:TSX:0025:00Drains to be provided at lowest points of temporary piping.

Sampling point to be provided atleast 5 metres away from theacid mixing point.Second sampling point at the tail (farthest end from acid mixingpoint of the circuit.

Temporary lines connecting main boiler up to first isolating valveshould withstand 40 Kg/Cu.Cm. Accordingly, the pipe selection tobe made.

Rubber lined valves should be provided in the entire chemical

injection system upto the final injection point in the main feedingline. The regulating valves should be of bottom diaphragm type.

Pressure gauges in the chemical injection system should be ofdiaphragm type.

Rubber lining provided in the various valves and pipe lines shouldbe resistant to heat, acid and alkali.

15 Cu.M. tank to be epoxy coated internally and leak test to bedone before insulating the tank.

All temporary connections to Boiler should be of radiographicquality.

40 Cu.M. tank to be leak tested before insulation.

2 Nos. of Acid Storage Tank to be spark tested (By the vendor).

Small drains not connected to neutrallsing pit to be neutralissedlocally with lime power and let into storm water canal.

Service water supply should be available near the pumpoperating areas.

Additional Checklists/Modifications in the lay-out, if foundnecessary, to be made at site in consultation with siteCommissioning Incharge.

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SHEET 33 of 40

10.f ALKALI BOIL OUT

LOG SHEET NO. 1

DATE:

PROJECT:UNIT :

I. ADDITION OF CHEMICALS:

DATE TIME (HRS) NAME OF CHEMICAL QUANTITYADDED.

II. ANALYTICAL DATA:

Sl. No. DateTime(HRS)

TotalAlkalinityasCACO3(PPM)

TotalPhosphte(PPM)

Silica(PPM)

Oil(PPM)

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SHEET 34 of 40

10.f BOILER CHEMICAL CLEANING

LOG SHEET NO. 2

DATE:

PROJECT:UNIT :

ACTIVITY : SUPER HEATER BACK FLUSHING & FILLING

ANALYTICAL DATA:

Sl. No. DATE TIME(HRS)

PH HYDRAZINEPPM

REMARKS.

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SHEET 36 of 40


LOG SHEET NO. 4

DATE:

PROJECT:UNIT :

ACTIVITY: DM WATER RINSE

ANALYTICAL DATA:

SL. NO DATETIME(HRS)

ACID %IRON(PPM)

REMARKS

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SHEET 37 of 40


LOG SHEET NO. 5

DATE:

PROJECT:UNIT :

ACTIVITY : CITRIC ACID RINSE



II. ANALYTICAL DATA :

Sl. No. DATETIME(HRS)

PHCITRIC

ACID %IRONPPM

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SHEET 38 of 40


LOG SHEET NO. 6

DATE:

PROJECT:UNIT :

ACTIVITY : DM WATER RINSE.

ANALYTICAL DATA:


PHIRON(PPM)

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LOG SHEET NO. 8

DATE:

PROJECT:UNIT :

ACTIVITY : PASSIVATION.



II. ANALYTICAL DATA:


PHHYDRAZINE(PPM)

REMARKS

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Documents

ABO AC