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
1.0
PLANT DETAILS
2.0
OBJECTIVE
3.0
PROPOSAL
4.0
SERVICES REQUIRED
5.0
SAFETY PRECAUTIONS
6.0
EMERGENCY PROCEDURES
7.0
STATE OF THE PLANT
8.0
METHOD
9.0
COMPLETION CRITERIA
10.0
APPENDICES
A. TECHNICAL SPECIFICATIONS
B. SAFETY CLEARANCE CERTIFICATE
C. MECHANICAL PLANT ITEM COMPLETION LIST &
ELECTRICAL PLANT AND C&I PLANT ITEM COMPLETION LIST
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 2 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY 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 located in 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
NTPC Ref No. SIM/1/TS/1/011
Sheet 3 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
1.0
PLANT DETAILS
STATUS
The HFO system consists of HFO day tank, 2 x 100% fuel oil
pressurizing pumps with heaters, controls, piping, valves and
fittings. The LDO system consists of LDO day tank with 1 x
100% LDO pressurizing pump with required controls piping.
Valves and fittings.
The boiler is equipped with a deaerator and feed pumps to
supply deaerated feed water at 105 Deg. C to the boiler.
Blow down system with blow down tank, HP and LP chemical
dosing system comprising tanks, pumps, piping valves and
fittings are also provided.
The boiler is equipped with two Radial FD fans (2x60%) with
electric motor drive.
The boiler and auxilaries will be complete with the required
accessories associated equipment, fittings and valves, integral
piping systems etc.
Complete air and flue gas ducting upto and including steel
chimney will be provided along with the required expansion
joints, damper and supporting steel work.
Refractory and thermal insulation, outer and inner casing
materials will be provided as required.
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 4 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
2.0
OBJECTIVE
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.
STATUS
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 5 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
3.0
PROPOSAL
STATUS
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
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 6 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY 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.
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 the
neutralisation of the alkali boil out effluent in line with A.P.
pollution control Board Norms
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 7 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY 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.
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 shall
be provided at all possible points of discharge, spillage or
escape of chemicals.
5.2.2
Adequate provisions shall be made for emergency treatment of
the eyes, comprising eye wash bottles, located conveniently to
places where charging of chemicals are planned.
5.2.3
Telephone facilities shall be provided within a reasonable
distance of the place where chemicals are being used
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 8 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
6.0
EMERGENCY PROCEDURES
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.
STATUS
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 9 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
7.0
STATE OF THE PLANT
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.
STATUS
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 10 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY 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.
8.2
Procedure
Prepare the boil out chemical solution in demineralised water
in a chemical mixing tank. The solution is formulated by
dissolving the following proportionate quantities of chemicals,
depending on the volume of the system to be cleaned.
1.
0.05% Na2 HPO4
2.
0.1 % Na3 PO4
12 H2O
12 H2O
8.3
Hold the solution prepared as above in the tank and
homogenise 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
Station : NTPC - Simhadri
BHEL
BHEL Ref No. PS-DC-186-500-0015
Sheet 11 of 14
NTPC Ref No. SIM/1/TS/1/011
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
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
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 12 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
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
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 13 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
10.0
APPENDICES
a.
TECHNICAL SPECIFICATION
1.
Boiler : Natural circulation water tube design, bottom
supported
2.
Boiler Drum
Drum ID
Shell Length
Material
3.
2897 mm
8258 mm
4242 mm
Super Heater
Tube O.D
No.of Assemblies
Heating Surface
5.
51.0 mm
15
13.75m2
Predicted Performance
1.
2.
3.
1.
2.
3.
5.
762(W)
8610
Furnace
Width
Depth
Height
4.
1219(S)
8810
SA515 Gr 70
Flow
SH Steam
Combustion Air
Flue Gas
Tonnnes
55.0
61.0
65.0
Pressure
Drum Operating
Drum Design
Steam Pressure at
SHO outlet
Kg/Cm2 (g)
21.4
25.0
18.0
Temperature
1.
At SHO
2150 C
Signatures
NTPC
BHEL
Station : NTPC - Simhadri
BHEL Ref No. PS-DC-186-500-0015
NTPC Ref No. SIM/1/TS/1/011
Sheet 14 of 14
Plant Area : BOILER
CHEMICAL CLEANING OF AUXILIARY BOILER
STATUS
6.
Sl.
No
SAFETY VALVES
LOCATION
VALVE SET
PRESSURE
KSC
VALVE
TAG NO
OPEN
CLOSE
%
BLOW
DOWN
1)
DRUM
SV1
25.0
24.0
4.0
2)
DRUM
SV2
25.8
24.7
4.3
3)
SH
SV3
20.5
19.6
4.4
REMARK%
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
Upper drum flooded
2.Lower drum
b.
3.9
11.3
4.2
3.water walls including Boiler bank tubes
18.7
4.SH system upto M.S.Stop valve
2.0
SAFETY CLEARANCE CERTIFICATE
List of signatories required before running the system
will be mutually decided at site.
c.
MECHANICAL /ELECTRICAL/C & I PLANT ITEM
COMPLETION LIST
The plant item completion list for the above areas will be
mutually prepared at site by BHEL and NTPC.
Signatures
NTPC
BHEL
CHEMICAL CLEANING OF AUXILIARY BOILER
PROGRESS REPORT : SG 16
JULY 2001