procedure for commissioning of auxiliary prds system

7/22/2019 Procedure for Commissioning of Auxiliary Prds System

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Station: NTPC- Simhadri BHEL Ref No.PS-DC-186-500-0039

NTPC Ref no SIM/1/TS/1/39Sheet 1 of 13

Plant area: BOILER

PROCEDURE FOR COMMISSIONING OF AUXILIARY PRDS SYSTEMSLNO

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LIST OF CONTENTS

PLANT DETAILS

OBJECTIVE

PROPOSAL

SERVICES REQUIRED

SAFETY PERECAUTIONS

EMERGENCY PROCEDURE

STATE OF THE PLANT

METHOD

COMPLETION CRITERIA


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Plant area: BOILERPROCEDURE FOR COMMISSIONING OF AUXILIARY PRDS SYSTEM

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PLANT DETAILS

Auxiliary steam system is designed to provide steam for theturbine auxiliaries, boiler auxiliaries and fuel oil heating systemduring start-up, low loads and normal running of units.

The system comprises of two auxiliary steam pressure reducing

and desuperheating stations (PRDS). One High capacity PRDSwith tapping off steam from main steam line to meet auxiliarysteam requirements during unit start-up, low loads, fuel oil systemand F.O. wagon unloading and the other Low Capacity PRDSwith tapping off steam from CRH line to meet auxiliary steamrequirements during normal running. Spray water required fordesuperheating will be tapped off from boiler feed pumpdischarge.

These two stations will reduce the pressure and temperature ofthe steam tapped off from CRH line and main steam line to

16Kg/ cm

2

(abs) & 320

0

C at the high temperature auxiliary steamheader and subsequently to 16 Kg/ cm2 (abs) & 2100C at the lowtemperature auxiliary steam header through a suitabledesuperheater between the high temperature and lowtemperature auxiliary steam headers.

The two auxiliary steam PRDS comprises of high capacitycombined pressure reducing & desuperheating valve AD-22, lowcapacity PRV, spray water pressure & temperature control valvesfor high temperature header and low temperature header, a blockvalve in common spray line and a desuperheater between hightemperature header and low temperature header.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER

PROCEDURE FOR COMMISSIONING OF AUXILIARY PRDS SYSTEM

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Motorized bypass regulating globe valves have been provided forlow capacity PRV and LT header spray control valves which canbe operated remote manually in case of mal-operation of maincontrol valve.

The systems which are supplied with Auxiliary Steam from HTUnit auxiliary steam header are

a) BFP Turbine & Gland Sealing

b) Seal Steam to main turbine

c) Mill inerting

d) AH Soot blowers

The systems which are supplied with auxiliary steam from LT UnitAuxiliary Steam Header are

a) SCAPH

b) F.O Atomisation

c) Deaerator Pegging

d) Fuel Oil Pump House

e) Fuel Oil Storage / Unloading yard.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER

PROCEDURE FOR COMMISSIONING OF AUXILIARY PRDS SYSTEMSL.NO

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The change-over from Low capacity PRDS to High capacityPRDS & vice-versa is automatic with manual override facility.During high capacity PRDS operation, low capacity PRDSremains in operation.

The low & high capacity PRDS can be operated independentlyeither in auto or remote manually from the unit control desk.However, manual operation overrides the auto operation.

Auxiliary steam system is normally operating on unit basis,however auxiliary steam system of both the units areinterconnected through HT and LT auxiliary steam headers, sothat unit start-up requirement of one unit can be met from otherunit or vice-versa.

An auxiliary boiler has been envisaged for initial start-up of theunit and fuel oil heating. For starting the units, boiler has to run onlight oil and steam thus generated will be used for unit start-up.

The control valves in PRDS are of modulating type.

Plant item completion list for mechanical, Electrical C&I area tobe prepared at site.

OBJECTIVE

The objective of this procedure is to commission the AuxiliaryPRDS system and make it available for Unit operation.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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PROPOSAL

Auxiliary PRDS system will be commissioned through thefollowing proposals.

Commissioning of L.T. Station and Unit Auxiliary Steam Headerthrough Auxiliary Boiler.

Commissioning of H.T. Unit and station Auxiliary Steam Headerthrough

a) High Capacity (HC) Steam line from MS.line

b) Low Capacity (LC) Steam line from CRH

Safety valve floating of H.T Auxiliary Steam Header

Remote / Auto operation of all control System with envisagedinterlocks.

SERVICES REQUIRED

Availability of Auxiliary Boiler for operation.

Availability of Main Boiler for operation.

Availability of lighting, Communication at PRDS area.

Availability of Man Power for conducting the activity.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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SAFETY PRECAUTIONS

Availability of first aid kit at test area.

The team commissioning the fan should be aware of theprocedure adopted.

Agencies working in the boiler area / associated ducting system

are informed about the test / cleared from the test area (As perthe actual requirement).

All loose materials around the fan area are cleared.

Required approach stair cases, platforms and hand rails areerected prior to testing.

Oil collecting trays and sand buckets are made available at testarea.

EMERGENCY PRECAUTIONS:

The group conducting the test should be aware of action to betaken on the event of injury to personnel.

The group shall be aware of operating instruction of portable fireextinguishers.

The test team should be aware of the steps to be taken to trip therunning equipment in case any emergency / abnormalobservations are notified to them.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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STATE OF THE PLANT

Installation of H.T and LT Auxiliary Steam Station & Unit headerscompleted in all respect Namely,

a) Erection of the headers completed.

b) Hydraulic Test of headers completed

c) Supports completed

d) Insulation completed

Drain lines of the H.T. & L.T. Headers (Station & Unit) are safelyrouted to an outlet, supported and insulated.

Erection of pipe line to different system (Sec 1.5 & 1.6) completedand their respective isolating valves kept closed.

Safety valves 3 Nos (As-32, AS-33 and AS-34) are erected andtheir exhaust, drip pan and drain lines are erected andcompleted.

Suitable exhaust pipe lines are laid for the following Headers /Steam lines for steam blowing.

a) High Capacity (HC) Steam inlet line from M.S line.

b) Low Capacity (LC) Steam inlet line from CRH line

c) H.T Steam headers of both Station and Unit auxiliarysystem.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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Steam blowing of Steam line from Auxiliary boiler to LT Aux.Steam header completed (Refer to procedure for SB and oilflushing of F.O System)

All manual valves in the system are erected and their freeoperation ensured.

All the control valves and motorized operated valves in

a) High Capacity Steam inlet line from MS line

b) Low Capacity Steam inlet line from CRH

c) Desuperheat line to HC and LC steam lines.

Are commissioned and are available for remote manual and Autooperation.

Required local/Remote instrumentation inputs are madeavailable. (List to be prepared at site)

METHOD

(Refer Drg.No. PE-DG-186-100-0107)

Commissioning of L.T Auxiliary Steam Header ThroughAuxiliary Boiler

Prepare and put the auxiliary boiler under Steaming condition ataround 25% of its MCR rating

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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Charge slowly the Steam line from auxiliary boiler up to L.T.auxiliary steam header in main boiler. All the required drains andvents are lined up before charging and all the outgoing valvesfrom the Auxiliary headers are Kept closed.

(Charging done through AS-56, As-48 and AS-47)

While charging, increase the fuel loading of the auxiliary boiler

sufficiently to warm up the line as well as to gradually pressurizethe system.

The L.T. auxiliary header is charged to around 14-16 KSC at 200-210

0C.

After attaining more or less a steady condition, Steam blowing of

a) Steam line to SCAPH and

b) Steam line to F.O. Atomisation carried out.

Suitable steam exhaus provisions are made for the above twocircuits and steam blown for about 10 minutes for two times witha time gap of 15 minutes between the blows.

Valves AS-45 and the individual system inlet valves are used forthis blowing. After completion of steam blowing of the above twosystem, (Sec.8.5) the steam lines are normalized with thesystem.

Steam line to Deaerator pegging will be steam blown on similarlines as enplaned above. Alternatively, this line can be steamblown by charging L.T. auxiliary steam header through HC/LCsteam lines from M.S line / CRH lines respectively.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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Since AH Soot blowing is required during initial oil firing onwards,AH sootblower steam line connected to H.T. Unit Aux. Steam Hdris steam blown by charging steam from Auxiliary Boiler via H.T.

Auxiliary Station Header.

Local / Remote indications are verified for proper display ofparameters.

Commissioning of H.T. Auxiliary Steam Header through HC

Steam line from MSL.

After ensuring that main boiler is steaming with LDO burners,charge the HC steam line from MSL slowly through valves AS-21& AS-22 and steam blow the line for two times with 10 minutesblwing duration and 15 minutes gap between the blows. (The inletpressure to be around 10 KSC).

All the required drains and vents are lined up before charging.

After the H.T. Unit Auxiliary Steam Header is then charged to

around 14-16-KSC at 300-320

0

C

The following steam lines are steam blown from H.T Unit Aux.Steam Header

a) Steam line to Mill inerting

b) Steam line to AH sootblower (same as 8.9)

c) Steam line to Main Turbine Gland Seal

d) Steam line to BFP Turbine & Gland Seal.

(These are steam blown as per erection readiness)

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


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Suitable steam exhaust provisions are made for the above andSteam blown for about 10minutes for two times with a time gap of15 minutes between the blows.

Valves AS-38, AS-39, AS-40 and AS-41 along with individualsystem inlet valves are used for this blowing. After completion ofsteam blowing, the lines are normalized with individual system.

Local / Remote indications are verified for proper display of

parameters.

Commissioning of H.T. Auxiliary Steam Header through LCSteam line from CRH.

After ensuring that the Unit is put under HP/LP bypass operation,charge the Low Capacity (LC) steam line from CRH slowlythrough valves AS-28 and AS-29 and steam blow the line for twotimes with 10 minutes blowing duration and 15 minutes betweenthe blows.

The inlet pressure to be around 5 KSC.

Required drain and vents kept open prior to steam blowing.

After completion of steam blowing, the LC line normalized withHC line vis--vis H.T Aux Steam Header.

SAFETY VALVE FLOATING

Safety valve with higher set pressure will be floated first followedby other two safety valves. Required safety valve gags are putsuitably while carrying out safety valve floating.

Steam pressure raising and lowering to be done suitably at local.

STATUS

Signatures

NTPC BHEL


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Plant area: BOILER


8.24 Procedure for commissioning of Auxiliary boiler to referred forsafety valve floating and adjustments.

(BHEL Reg: PS-DC-186-500-0030/NTPC ref. No SIM/1/TS/3/30).

Remote / Auto operation and Control System Interlocks.

The following controls and interlocks for PRDS are made

available.

1) Pressure control at 16 KSC by AS-22 or AS-26

2) Temperature control of HT header by FD-31

3) Temperature control of LT Header by FD-35

4) When AS-22 opens more than 2% then autoopening of

a) AS-21b) FD-29,30,31,33,34,35,and 43

5) When AS-22 is fully closed, then auto closing of

a) AS-21b) FD-29,30,31

6) When AS-26 opens more than 2%, than the autoopening of

a) AS25b) FD- 33,34,35 and 43

STATUS

Signatures

NTPC BHEL


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Plant area: BOILERPROCEDURE FOR COMMISSIONING OF AUXILIARY PRDS SYSTEM

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7) When AS-26 is fully closed, then auto closing of a)AS-25

8) When both AS-22 & AS-26 are fully closed, thenauto closing of

a) FD-33,34,35 and 43

9) Operation of AS-26 only when CRH pressure is morethan 18 KSC.

10) Auto change over from LC-PRV to HC-PRV and viceversa.

11) Temperature High 3400C& 230

0C for HT& LT

systems

12) Temperature Very High - 3500C& 2400C for HT& LT

systems

COMPLETION CRITERIA

Commissioning of Auxiliary PRDS system is completed bycarrying out all the proposals given in Section 3.0

The system released for regular operation.

STATUS

Signatures

NTPC BHEL


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PROCEDURE FOR COMMISSIONING OF

AUXILIARY PRDS SYSTEM

procedure for commissioning of auxiliary prds system

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