2LongTermPlan OverHaul-LTP OH.PPT

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LONG TERM PLANNINGAND

OVERHAULING

PRACTICES IN NTPC



WHY OVERHAULING IS

REQUIRED ?

• Performance

• Reliability

• Availability

• Safety• Environment

• Cost

•Statutory Requirement

PRASECS



PERFORMANCE

• Generation

• Heat Rate

• Parameters• Specific oil consumption

• Auxiliary power consumption

– Motor current – Capacity deterioration

– Utilising stand by eqpt.



RELIABILITY

• Routine and repetitive maint.

• Poor performance of eqpt.

• Unplanned Breakdowns – High vibration of eqpt.

– Abnormal noise

–High Temperature

– Leakages



AVAILABILITY

• ABT

• Availability of stand by eqpt.

•Availability of complete stream



SAFETY

• Safety of the equipment

• Safety valves

•Poor condition of internals

• Safety of electrical eqpt.

• Condition of flow path



ENVIRONMENT

• Flue gas emissions

– Air control act

•

Noise• Ash water

• Effluents



COST

• Cost of generation

• Coal input

•Water consumption

• Oil consumption

• Auxiliary power consumption



Statutory requirement

• Boiler certificate renewal



WHEN TO DO OVERHAULING ?

• Summary of PRASECS• Grid condition

• Customer requirement• CERC Clearance

• Condition of other units of thestation

• MOU Target



LONG TERM PLANNING

• Life cycle plan for 25 – 30 years

• Regional Eight years rolling plan

•Station Eight years rolling plan

• Engineering declaration

• Annual location plan

• Spares procurement plan



LIFE CYCLE PLAN

• Likely trend of replacement of theequipment/parts which are likely to failbefore the life expectancy

• Factors for replacement

– Coal quality – Creep life of various components

– Equipment duty conditions

– Wear rate – Behavioural trend of plant/ equipment & its

past history

– RLA Reports



MAJOR EQUIPMENT TO BE

COVERED IN LIFE CYCLE PLAN

• Gear Reducers

• Slurry pumps

•Coal crushers

• Conveyor Drives in CHP

• Chemical piping



Cont’d

Boiler Pr.Parts• Super heaters

• Re-heaters

• High Pr. Valves

• Safety valves



Cont’d

• Turbine & Aux.

– Turbine rotor blades

– Turbine bolts

– Boiler feed pump rotor

– H.P. Heater coil



Cont’d

• Electrical

– H.T.Motor

– Transformer

– Switch gears

– Cables



Regional Eight years rolling plan

• Minimum number of units at a time

• Regional electricity boards

•Regional grid demand

• Capital investment and revenue budget

• Unit/station merit rating based on

efficiency and economics of generation



Define region into station/plant & areas

Consider plant life & potentialProblems In each station/unit

Formulate repair plans with cost data

Evaluate

Interim plan

Region/station rolling plan

Station location plan

Engg input

From similarplants

Maint. EngnrInput

Statutoryrequirement

PlantBetterment

plans

ResourceSpares

& materials

ResourceSkill and

T&P

Managementinput

Eight year rolling planFlow chart



Station Eight year rolling plan

• Detail plan for first three years

• Diagnostic inspection and majorreplacements in subsequent years

• Modest updating each year



Station annual location plan

• Detailed account of operation and maint. Of thecurrent year and plans for the next year.

• The plan should consist Unit merit rating basedon its performance in the last one year.

• Justification of heavy expenditure forimprovement and modifications

• Resource availability analysis

• Fuel cost

• Generation cost



ENGINEERING DECLARATION

• Brief review of the past performance of the unit

• Objectives of the proposed overhaul

• Scope of work

• Resource plan

• Returns in terms of gain in reliability andefficiency

• Engg declaration to be issued 24 months aheadand reviewed periodically (six monthly)



Format of Engg. Declaration

• Unit no

• Boiler license no

• Boiler license validity

• Overhaul history• Unit mile stones/ Major event

• Unit performance history

• Root cause analysis on Boiler tube leakagesand action plan

• Root cause analysis on trip and action plan



Cont’d

• Major eqpt. Failure history

• Parameters assessment

•Work module

• Financial justification

• Techno economic evaluation

• Bar chart• Exception of condition monitoring reports



Planning process of unit outage

• Pre shut down planning activities

• Shut down activities

•Post shut down activities



activities

• Plan to start from the time unit issynchronised.

• Engg declaration

• Spares and materials schedules• Quality plans

• Recommissioning Schedules

• Defect work orders pending• PRE SHUT DOWN SURVEY



Resources

• Spares & consumables

• Manpower

• Contracts

• Special T&P

• Material handling equipment like cranes,lifts and transport

• Availability of manufacturing facilities• Communication facilities



Cont’d

• Testing facilities like radiography, hydrotest etc.

• Temporary store & office cubicles

• Dispensary & ambulance at site

• General amenities for additional workforce

• Input from other departments



PRE SHUTDOWN SURVEY

• Equipment general condition

• Condition of bearings, filters and coolers

•Condition of APH – Pressure differential

– Heat pick up across APH

– Parameters of primary ,secondary air & fluegas

– Oxygen in flue gas



Cont’d • ESP

– Ash evacuation capacity

– Heating system

– Flue gas emission

– Leakages through manholes – ESP inlet & outlet Temperatures.

•Coal mills – Reject rate

– Coal fineness

– Leakages



Cont’d •

Boiler – Boiler expansion

– Leakages through manholes, peep holes

– Coal leakages

– Burner tilt mechanism

– Soot blower status

• Valves & Fittings

– Steam leakages – Steam passing

– Local/remote operation



Cont’d

• Ducts & Dampers

– Hot air leakages

– Air suction in the gas path

– Ash leakages

– Leakages at expansion joints

– Dampers operation from local & remote

– Dampers isolation

– Duct insolation



Cont’d

• Turbo Generators

– Bearing condition

– Vibration & Temp

– Oil leakage

– Analysis of lub oil

– Operation of control valves

– Leakage of hydrogen

– Stator water DP



Cont’d

• Motors

– Bearing vibration

– Lubrication & Temp. rise

• Transformers

– General condition of oil

– Dielectric strength



Execution

• Unit shut down• Issue of PTWs• Daily overhaul review meeting• Follow up of the bar chart• Filling the quality check sheets• Return of PTWs• Recommissioning activities

• Boiler hydro test• Unit light up• Unit synchronisation



Post overhaul review

• Deviation from the planning if any

• Performance of contracting agencies

•Plant parameters review

• Overhaul report



SCOPE OF WORK

PRESSURE PARTS



PRESSURE PARTS

WATER WALL ‘S’-Panel: All corners & L&R walls inspn. & repairs

Burner transition & corner tubes inspn. & repairs,TT survey in erosion prone areas, HP Jet cleaning,

DPT of scallop bar, support & ww tubes in deadchamber, Bottom ring header inspn.

WW screen & hanger tubes inspn.

LTSH Coils lifting (condition based), Inspection of Bifurcationbends, Cassette baffles & Terminal tubes inspectionDPT of hanger tubes & TT survey

PLATEN SH /FINAL SH

Spacer tube healthiness checking & TT survey

DPT of Lugs to tube welding

DIVISIONALSH

Scissor tubes sleeves, lugs inspn. & repairs and DPT ofLugs to tube welding, TT survey

STEAMCOOLED

WALL

TT survey in Screen tubes, tubes near manholes, Gapbetween LTSH coil & steam cooled wall, Eco coil& SCW,mechanical rubbing due to cassette baffles, stubs ofSHH-4A &4B

PRESSURE PARTS



PRESSURE PARTS CONTD..

REHEATER Spacer tube healthiness checks & lugs inspn.ORIFICE FIXING ? & TT survey

ECONOMISER Coils lifting (Condition based)DPT of root joints of stubs of Inlet headerCassette baffles & hanger tubes inspection & TTsurvey

DRUM Drum inspection

Drum ‘J’-bolts inspn. & DPT

HANGERS Pre O/H & Post O/H readings comparisionSurvey of Cold readings & Adjustment, if any

SAFETY V/Vs& ERVs

Defective Safety valves & ERVs (Condition based)overhauling/Servicing

SOOT BLWRS Soot blowers overhauling & LRSBs servicing

PENT HOUSE Inspection of supports, headers, vents, DPT of roots,attachment weld joints& all header joints

PRESSURE PARTS



PRESSURE PARTS CONTD…

BURNERS 36 NO.S of Coal nozzles replacementAir/oil nozzles in-situ repair (condition based)

SADC/BURNER TILT CHECKSNMEJs Repair & Rectification of defective portion of joints

after pre-overhaul survey

QUICK ERECTSCAFFOLDING

Erection of QES and Thorough inspection & cleaningof Water walls, Divisional panel

WIND BOX Cleaning, Inspection & repairs

BOILER

EXPANSIONS

Expansion indicators checking for any foulingproblems

HP VALVES CC pump- discharge v/v bonnet leakage, CBD v/vs,MS, Spray v/vs, root valves gland packingreplacement

BOILER

SUPPORT SYST

Boiler support systems checks as per LMI

ROTATING MACHINES



ROTATING MACHINESMILLS 2 No.of Mills Overhaul , Lub station servicing

FEEDERS 8 no.of RC feeders overhauling

DAMPERS &GATES

Dampers & gates overhauling & Passing problemsrectification

FANS All fans servicing, Blade pitch control servicing,

silencer cleaning, Visual inspection of shaft, welds &NDT. Lub station servicing.

AIR PREHEATERS

Damaged baskets replacement, if anyRadial / Axial seals inspn, repairs & replacementAll bearings/ gear boxes inspectionOverrunning clutches problems attending.SCAPH heat transfer areas inspn , cleaning & repair

DUCTS &

DAMPERS

Air & Gas duct inspection & repairsRepair of defective dampers & servicing of diversiondampers

ASH HANDLING SYSTEM



ASH HANDLING SYSTEMBOTTOM ASHSYSTEM

Repair of refractory, Seal trough & viewglasses inspection & cleaning, Clinker

grinders rollers (2 sets) replacement, SSpipes replacement, Feed gate seal & barrelreplacement & attending to passingproblems, Bottom ash nozzles inspectionBA discharge new lines connection

FLY ASHSYSTEM

Fly ash slurry line rotation/ replacement,Collector tanks & Air washers inspection,Vacuum line valves servicing, All vacuumlines washing, Vacuum pumps servicing,

Collector seal boxes repairs.

ESP Emptying of all hoppersAll ESP internals cleaning,inspection/ repairs

TURBINE & AUXILIARIES



TURBINE & AUXILIARIES

MAINTURBINE

CF trip oil line modification for proving ATT, & TurbineGoverning characteristics checking,

Turbine actual over speed testing

TDBFPs Euroflex coupling inspection, Turbine actualoverspeed test, MDBFP-2C discharge NRVreplacement, ACV & MCV pilot valves servicing &recirculation control valves inspection & repairs.TDBFP-2A&2B exhaust duct insulation & plastering

DMCW & ACW DMCW pump-B overhaul & suction strainers cleaningDMCW,ACW & CW system butterfly valves servicing(600 NB: 6 no.s, 800 NB : 8 no.s) PU coatinginspection & repairs, Self cleaning filters inspn

CONDENSER Condenser Water box tube cleaning, FRE lining inspn

Hotwell & Deaerator cleaning & condenser flood testCEPSs suction strainers cleaning.

CW DUCT CW duct PU coating inspection & repairs.

VALVES Turbine MAL valves, HTPRDS spray valves

OFF SITES (MECHANICAL)



OFF-SITES (MECHANICAL)

CW PUMPS CW pump- 3,4 & 5 volute inspection for

poly -glass coating.

CW pump butterfly valves inspection &operational checks

CW DUCT CW inlet & Outlet duct inspection &PU coating repairs.

COOLING

TOWER

CT nozzles inspection / cleaning

CT nozzles & drift eliminators repairs /replacement.

CT basin cleaning.

EM LT SWGR



EM-LT SWGR

LT switch gear sections overhaul

Bus/Modules/breakers/relays/contactors/transducers/timers

Cable shifting / interchangingTesting of protections of incomers/

bus couplers / auto change over

schemes as per LMI

EM SWYD / HT SWGR



EM-SWYD / HT SWGR

Insulators replacementCTs replacementBus tightnessHT switch gears PM

EM GENERATOR



EM-GENERATOR

Stator & Rotor InspectionCore inspectionHydrogen & Exciter coolers servicingExciter servicingTesting of excitation as per LMIInspection & protection of water cooled

generator stator winding

Prevention & detection of generator rotorearth faults as per LMI

TRANSFORMERS



TRANSFORMERSTransformers cleaning

OLTC, Conservators cleaningProtection elements checkingSilica gel replacement

Oil samplingOil flushingTesting

HT & LT M t



HT & LT Motors

Overhauling of motorsServicing of motorsBearings

Oil replacement / GreasingLugs inspectionFan inspection

LIGHT-UP TO SYNCHRONISATION



LIGHT UP TO SYNCHRONISATION

ACTIVITY UNIT-1(2003-04)

UNIT-2(2004-05)

UNIT-1(2004-05)

UNIT-2(2005-06)

UNIT-1(2005-06)

LIGHT-UP TOSYNCH.

25 Hrs 24.5Hrs

20.8 Hrs 20.0HRS

18 Hrs

LIGHT-UP TO

SAFETY V/VFLOATING START

7.2 Hrs 6.7 Hrs 6.5 Hrs 14.4*

HRS12.5Hrs

SAFETY V/VFLOATINGDURATION

5.5 Hrs 5 Hrs 3 Hrs 4.5HRS

4.4 Hrs

SAFETY V/VFLOATING TOTG 3000 RPM

5.2 Hrs 3.3 Hrs 4.5 Hrs 0.8HRS

0.9 Hrs

ELECTRICAL

TESTS DURATION

5 Hrs 7.75

Hrs

6 Hrs 5.0*

HRS4.3 Hrs

PRESSURE PARTS (Cont’d)



PRESSURE PARTS (Cont’d) QUICK ERECT SCAFFOLDING

UNIT-1(2003-04)

UNIT-2(2004-05)

UNIT-1(2004-05)

UNIT-2(2005-06)

‘QES’

ERECTION8.5

DAYS7.0

DAYS

5.5DAYS

5.5DAYS

‘QES’

DISMANTLING4.5

DAYS2.0

DAYS

2.9DAYS

3.0DAYS



FUEL OIL CONSUMPTIONUNIT YEAR HFO

KL

LDO

KL

TOTAL

KL

# I 2003-04 228 224 452

# I 2004-05 243 38 281

# II 2004-05 251 151 402

# II 2005-06 148 141 289

# I 2005-06 - - 170



THANK YOU

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2LongTermPlan OverHaul-LTP OH.PPT