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Station : NTPC - Simhadri BHEL Ref No. PS-DC-186-500-0015

NTPC Ref No. SIM/1/TS/1/011

Sheet 1 of 14

Plant Area : BOILER

CHEMICAL CLEANING OF AUXILIARY BOILER

SL.NO. LIST OF CONTENTS

PLANT DETAILS

OBJECTIVE

PROPOSAL

SERVICES REQUIRED

SAFETY PRECAUTIONS

EMERGENCY PROCEDURES

STATE OF THE PLANT

METHOD

COMPLETION CRITERIA

APPENDICES

A. TECHNICAL SPECIFICATIONS

B. SAFETY CLEARANCE CERTIFICATE

C. MECHANICAL PLANT ITEM COMPLETION LIST &

ELECTRICAL PLANT AND C&I PLANT ITEM COMPLETION LIST

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

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Sheet 2 of 14

Plant Area : BOILER


1.0 PLANT DETAILS STATUS

The Steam generator is of natural circulation. Water tube

design. arranged for pressurized firing. Basically it is a two drum

vertical bent tube arrangement with water cooled furnace walls

combined with the convective boiler bank surface. The complete

steam generator is of the bottom supported design resting on

concrete pedestals.

The upper and lower drums are connected by the bank tubes.

The steam drum is provided with efficient internals for steam

separation. The unheated down comers are located in the rear

half of boiler side wall ensures adequate circulation in the boiler.

The boiler bank tubes are arranged in line for the best heat

absorption. Minimum draft loss and easy tube inspection and

cleaning. Required accessibility is provided at the side of the

boiler bank convective surface. Adequate peep holes are

provided to watch the flame.

Feedwater is fed into the upper drum and circulation is

maintained in the boiler bank through the downcomers. From

the bottom drum water flows through the heat absotbing

furnace tubes and back into the steam drum. After separation of

moisture in the internals, the saturated steam flows through

superheaters and to SH outlet steam collecting header from

where the main steam is tapped off.

The main fuels are Heavy Fuel Oil and Light Diesel Oil. The

firing system consists of one no oil burner with register locatedin the front wall to carry MCR capacity with either of the fuels.

The fuel oil is steam atomized: light oil is air atomized. High

Energy Arc (HEA) ignitor is used for lighting up the burner. A

flame scanning system is provided to monitor the flame

condition in the furnace.

Signatures

NTPC BHEL

Station : NTPC - Simhadri BHEL Ref No. PS-DC-186-500-0015 Sheet 3 of 14

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2.0 OBJECTIVE STATUS

2.1 The objective of this commissioning schedule is to clean the

internal surface of the steam generating portion and heating

surface (Economiser) using specified chemicals.

Signatures

NTPC BHEL



Sheet 5 of 14

Plant Area : BOILER


3.0 PROPOSAL STATUS

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The objectives are achieved by carrying out the following

testing proposals.

3.1 By carrying out an effective boil-out, grease, oil and any

protective coatings applied are removed from the interior

pressure parts of the auxiliary boiler

Signatures

NTPC BHEL



Sheet 6 of 14

Plant Area : BOILER


4.01 SERVICES REQUIRED STATUS

All the required quantities of chemicals as given below should

be made available prior to the commencement of the process.

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SPECIFICATION OF CHEMICALS & QUANTITY

NAME OF CHEMICALS

1. Trisodium Phosphate (Na3PO4. 12H2O) 30 Kg

(IS:573/1992)

2.Disodium Phosphate(Na2 HP O4.12 H2O) 15 Kg

(IS:566/1991)

4.02 Supply of adequate DM water to be ensured

4.03 415 V Supply available

4.04 220 AC/Dc, 110V AC, Control Supply available (Which ever is

applicable).

4.05 Instrument / Service Air Available

4.06 Flood Lights / Telephones / Walkie - Talkie are available

4.07 Ambulance / car for emergency / fire tender available

4.08 Drum level guage glass should be made available with lighting

arrangement and tale-tale switch cum light arrangement

4.09 Sufficient quantity of Raw/Fire water to be ensured for theneutralisation of the alkali boil out effluent in line with A.P.

pollution control Board Norms

Signatures

NTPC BHEL



Sheet 7 of 14

Plant Area : BOILER


5.0 SAFETY PRECAUTIONS STATUS

5.1 SAFETY EQUIPMENTS : ENSURE THE AVAILABILITY OF

1. GUM BOOTS (Various Sizes) 6 Pairs

2. Rubber Gloves 6 Pairs

3. Rubber or Polythne Aprons 6 Nos.

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4. Helmets 12 Nos.

5. Safety Goggles Plain Glass 6 Nos.

6. Face Mask (Transparent, Plastic) 4 Nos.

7. First aid box (containing dilute ammonium hydroxide, 50%sodium bicarbonate solution, eye loction, bandages,tincture of idodine, cotton, burnol etc.

8. Safety shower.

EMERGENCY PROVISIONS

5.2 Flushing and washing water supplies

5.2.1 Ample supplies of flushing and washing water supplies shallbe provided at all possible points of discharge, spillage orescape of chemicals.

5.2.2 Adequate provisions shall be made for emergency treatmentof the eyes, comprising eye wash bottles, locatedconveniently to places where charging of chemicals areplanned.

5.2.3 Telephone facilities shall be provided within a reasonabledistance of the place where chemicals are being used

Signatures

NTPC BHEL

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Sheet 8 of 14

Plant Area : BOILER


6.0 EMERGENCY PROCEDURES STATUS

6.1 The testing team should be aware of the operating

procedures of fire extinguishers to be used for quenching

minor or major fires

6.2 The testing team should be aware of the procedure to be

followed in case of accident involving personnel injury.

Signatures

NTPC BHEL

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Sheet 9 of 14

Plant Area : BOILER


7.0 STATE OF THE PLANT STATUS

7.1 Auxilary Boiler erection must have been completed as per

approved scheme in respect of all ie. machanical, electrical

and C&I area.

7.2 Hydraulic test of boiler should have been completed to the

required parameter. Pl. specify the HYD. Test Pressure.

7.3 Preboiler system circuits should be available for operation.

7.4 For alkali boilout, minimum essential instruments required for

boiler light up are made available

7.5 Boiler should be ready for regular operation as per Q & M

instructions.

7.6 Sampling system should be ready.

7.7 Ensure free access to all equipment.

7.8 Ensure the readiness of fire fighting system as envisaged in

the design.

7.9 Ensure the availability of fire tender near the boiler area.

Signatures

NTPC BHEL

Station : NTPC - Simhadri BHEL Ref No. PS-DC-186-500-0015NTPC Ref No. SIM/1/TS/1/011

Sheet 10 of 14

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Plant Area : BOILER


8.0 METHOD STATUS

ALKALI BOIL OUT

8.1 The boiler (steam generating surfaces and economiser) is

filled with an alkaline solution containing 500 ppm of

disodium phosphate dodeca hydrate, and 1000 ppm of Tri

sodium phosphate do deca hydrate and then fired to raise

the pressure to 10 kg/ cm2, following the specified

operational procedures.

8.2Procedure

Prepare the boil out chemical solution in demineralised waterin a chemical mixing tank. The solution is formulated bydissolving the following proportionate quantities ofchemicals, depending on the volume of the system to becleaned.

1. 0.05% Na2 HPO4 12 H2O

2. 0.1 % Na3 PO4 12 H2O

8.3 Hold the solution prepared as above in the tank andhomogenise the same by proper mixing the solution.

8.4 Start filling the Aux. boiler with demineralised water, until the

water is seen little above the bottom of the upper drum.

8.5 Pour the chemical solution with the drum through the manhole

by several increments.

8.6 Close the man hole cover and fill up with DM water upto

normal operation level.

Signatures

NTPC BHEL



Sheet 11 of 14

Plant Area : BOILER


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STATUS

8.7 Light up the boiler as per O & M instructions and gradually

raise the pressure to 10 Kg/CM2 . Hold the pressure for four

hours. Prescribe blow down every 2 Hrs. Once, after killing the

fire; Duration of the blow down shall be for one minute Ensure

that the drum level does not go out of gauge glass vision.

8.8 Repeat the operation of raising the pressure to 10 kg/cm2 and

prescribing blow down every 2 hours (Total 4 Blow downs)

after killing fire.

8.9 The boil out is declared completed when minimum 4 blow

downs are completed.

8.10 Drain the boiler, when it is cooled, as per O & M instructions.

Once the draining is completed, fill the boiler with

demineralised water, through boiler fill pump. Back flush the

superheaters with DM water containing 200 ppm hydrazine

and pH 10.0 with NH3 till it overflows into the drum. Drain the

boiler to the waste disposal system. Inspect the upper drum

and manually clean, if any loose muck and sludge are

present.

8.10 The effluent of alkali boil out shall be neutralised and

disposed in line with A.P. pollution control Board norms.

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

dilution with raw / fire water.

Signatures

NTPC BHEL



Sheet 12 of 14

Plant Area : BOILER


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9.0 COMPLETION CRITERIA STATUS

The completion criteria is time based boil out at 10 kg

persg.cm for 10 hrs with intermittent blowdown at once in 2

hours with each blowdown for 1 minute Duration. Drum is

inspected and all the loose muck and other dirts are cleaned( Upper Drum )

Signatures

NTPC BHEL

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Sheet 13 of 14

Plant Area : BOILER


10.0 APPENDICES

a. TECHNICAL SPECIFICATION

1. Boiler : Natural circulation water tube design, bottomsupported

2. Boiler Drum

Drum ID 1219(S) 762(W)Shell Length 8810 8610Material SA515 Gr 70

3. Furnace

Width 2897 mmDepth 8258 mmHeight 4242 mm

4. Super Heater

Tube O.D 51.0 mmNo.of Assemblies 15Heating Surface 13.75m2

5. Predicted Performance

Flow Tonnnes1. SH Steam 55.02. Combustion Air 61.03. Flue Gas 65.0

Pressure Kg/Cm2 (g)

1. Drum Operating 21.42. Drum Design 25.03. Steam Pressure at

SHO outlet 18.0

5. Temperature

1. At SHO 2150 C

Signatures

NTPC BHEL

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Sheet 14 of 14

Plant Area : BOILER


STATUS

6. SAFETY VALVES

Sl.No

LOCATIONVALVE

TAG NO

VALVE SETPRESSURE

KSC

%BLOWDOWN

REMARK%

OPEN CLOSE

1) DRUM SV1 25.0 24.0 4.02) DRUM SV2 25.8 24.7 4.3

3) SH SV3 20.5 19.6 4.4

NOTE: Percentage blow down to be within 3% -5% of value lifting pressure

7. Water Valume in m3

1.Upper drum upto normal water level 3.9

Upper drum flooded 11.3

2.Lower drum 4.2

3.water walls including Boiler bank tubes 18.7

4.SH system upto M.S.Stop valve 2.0

b. SAFETY CLEARANCE CERTIFICATE

List of signatories required before running the systemwill be mutually decided at site.

c. MECHANICAL /ELECTRICAL/C & I PLANT ITEM

COMPLETION LIST

The plant item completion list for the above areas willbe mutually prepared at site by BHEL and NTPC.

Signatures

NTPC BHEL

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PROGRESS REPORT : SG 16

JULY 2001

Documents

ABO AUX