LONG TERM PLANNING AND 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 the station • 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 the equipment/parts which are likely to fail before 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 Engg input From similar plants Statutory requirement Consider plant life & potential Problems In each station/unit Maint. Engnr Input Plant Betterment plans Formulate repair plans with cost data Resource Spares & materials Evaluate Resource Skill and T&P Management input Interim plan Region/station rolling plan Eight year rolling plan Flow chart Station location plan Station Eight year rolling plan • Detail plan for first three years • Diagnostic inspection and major replacements in subsequent years • Modest updating each year Station annual location plan • Detailed account of operation and maint. Of the current year and plans for the next year. • The plan should consist Unit merit rating based on its performance in the last one year. • Justification of heavy expenditure for improvement 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 and efficiency • Engg declaration to be issued 24 months ahead and 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 leakages and 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 Pre shut down planning activities • Plan to start from the time unit is synchronised. • 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, hydro test etc. • Temporary store & office cubicles • Dispensary & ambulance at site • General amenities for additional work force • 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 & flue gas – 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 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 dead chamber, Bottom ring header inspn. WW screen & hanger tubes inspn. Coils lifting (condition based), Inspection of Bifurcation bends, Cassette baffles & Terminal tubes inspection DPT of hanger tubes & TT survey Spacer tube healthiness checking & TT survey DPT of Lugs to tube welding Scissor tubes sleeves, lugs inspn. & repairs and DPT of Lugs to tube welding, TT survey TT survey in Screen tubes, tubes near manholes, Gap between LTSH coil & steam cooled wall, Eco coil& SCW, mechanical rubbing due to cassette baffles, stubs of SHH-4A &4B LTSH PLATEN SH / FINAL SH DIVISIONAL SH STEAM COOLED WALL PRESSURE PARTS REHEATER ECONOMISER CONTD.. Spacer tube healthiness checks & lugs inspn. ORIFICE FIXING ? & TT survey Coils lifting (Condition based) DPT of root joints of stubs of Inlet header Cassette baffles & hanger tubes inspection & TT survey DRUM HANGERS SAFETY V/Vs & ERVs Drum inspection Drum ‘J’-bolts inspn. & DPT Pre O/H & Post O/H readings comparision Survey of Cold readings & Adjustment, if any Defective Safety valves & ERVs (Condition based) overhauling/Servicing SOOT BLWRS PENT HOUSE Soot blowers overhauling & LRSBs servicing Inspection of supports, headers, vents, DPT of roots, attachment weld joints& all header joints PRESSURE PARTS BURNERS CONTD… 36 NO.S of Coal nozzles replacement Air/oil nozzles in-situ repair (condition based) SADC/BURNER TILT CHECKS Repair & Rectification of defective portion of joints after pre-overhaul survey Erection of QES and Thorough inspection & cleaning of Water walls, Divisional panel Cleaning, Inspection & repairs Expansion indicators checking for any fouling problems NMEJs QUICK ERECT SCAFFOLDING WIND BOX BOILER EXPANSIONS HP VALVES BOILER SUPPORT SYST CC pump- discharge v/v bonnet leakage, CBD v/vs, MS, Spray v/vs, root valves gland packing replacement Boiler support systems checks as per LMI ROTATING MACHINES MILLS FEEDERS DAMPERS & GATES FANS AIR PRE HEATERS 2 No.of Mills Overhaul , Lub station servicing 8 no.of RC feeders overhauling Dampers & gates overhauling & Passing problems rectification All fans servicing, Blade pitch control servicing, silencer cleaning, Visual inspection of shaft, welds & NDT. Lub station servicing. Damaged baskets replacement, if any Radial / Axial seals inspn, repairs & replacement All bearings/ gear boxes inspection Overrunning clutches problems attending. SCAPH heat transfer areas inspn , cleaning & repair Air & Gas duct inspection & repairs Repair of defective dampers & servicing of diversion dampers DUCTS & DAMPERS ASH HANDLING SYSTEM BOTTOM ASH Repair of refractory, Seal trough & view glasses inspection & cleaning, Clinker SYSTEM grinders rollers (2 sets) replacement, SS pipes replacement, Feed gate seal & barrel replacement & attending to passing problems, Bottom ash nozzles inspection BA discharge new lines connection FLY ASH SYSTEM Fly ash slurry line rotation/ replacement, Collector tanks & Air washers inspection, Vacuum line valves servicing, All vacuum lines washing, Vacuum pumps servicing, Collector seal boxes repairs. Emptying of all hoppers All ESP internals cleaning,inspection/ repairs ESP TURBINE & AUXILIARIES MAIN TURBINE TDBFPs CF trip oil line modification for proving ATT, & Turbine Governing characteristics checking, Turbine actual over speed testing Euroflex coupling inspection, Turbine actual overspeed test, MDBFP-2C discharge NRV replacement, ACV & MCV pilot valves servicing & recirculation control valves inspection & repairs. TDBFP-2A&2B exhaust duct insulation & plastering DMCW pump-B overhaul & suction strainers cleaning DMCW,ACW & CW system butterfly valves servicing (600 NB: 6 no.s, 800 NB : 8 no.s) PU coating inspection & repairs, Self cleaning filters inspn Condenser Water box tube cleaning, FRE lining inspn Hotwell & Deaerator cleaning & condenser flood test CEPSs suction strainers cleaning. CW duct PU coating inspection & repairs. Turbine MAL valves, HTPRDS spray valves DMCW & ACW CONDENSER CW DUCT VALVES OFF-SITES (MECHANICAL) CW PUMPS CW pump- 3,4 & 5 volute inspection for poly -glass coating. CW pump butterfly valves inspection & operational checks CW inlet & Outlet duct inspection PU coating repairs. & CW DUCT COOLING TOWER CT nozzles inspection / cleaning CT nozzles & drift eliminators repairs / replacement. CT basin cleaning. EM-LT SWGR LT switch gear sections overhaul Bus/Modules/breakers/relays/contact ors/transducers/timers Cable shifting / interchanging Testing of protections of incomers/ bus couplers / auto change over schemes as per LMI EM-SWYD / HT SWGR Insulators replacement CTs replacement Bus tightness HT switch gears PM EM-GENERATOR Stator & Rotor Inspection Core inspection Hydrogen & Exciter coolers servicing Exciter servicing Testing of excitation as per LMI Inspection & protection of water cooled generator stator winding Prevention & detection of generator rotor earth faults as per LMI TRANSFORMERS Transformers cleaning OLTC, Conservators cleaning Protection elements checking Silica gel replacement Oil sampling Oil flushing Testing HT & LT Motors Overhauling of motors Servicing of motors Bearings Oil replacement / Greasing Lugs inspection Fan inspection LIGHT-UP TO SYNCHRONISATION ACTIVITY LIGHT-UP TO SYNCH. LIGHT-UP TO SAFETY V/V FLOATING START SAFETY V/V FLOATING DURATION SAFETY V/V FLOATING TO TG 3000 RPM ELECTRICAL TESTS DURATION UNIT-1 UNIT-2 UNIT-1 UNIT-2 UNIT-1 (2003-04) (2004-05) (2004-05) (2005-06) (2005-06) 25 Hrs 24.5 Hrs 20.8 Hrs 20.0 HRS 14.4* HRS 4.5 HRS 18 Hrs 12.5 Hrs 4.4 Hrs 7.2 Hrs 6.7 Hrs 6.5 Hrs 5.5 Hrs 5 Hrs 3 Hrs 5.2 Hrs 3.3 Hrs 4.5 Hrs 0.8 HRS 5.0* HRS 0.9 Hrs 4.3 Hrs 5 Hrs 7.75 Hrs 6 Hrs PRESSURE PARTS (Cont’d) QUICK ERECT SCAFFOLDING UNIT-1 UNIT-2 UNIT-1 UNIT-2 (2003-04) (2004-05) (2004-05) (2005-06) ‘QES’ ERECTION 8.5 DAYS 7.0 DAYS 5.5 DAYS 5.5 DAYS ‘QES’ DISMANTLING 4.5 DAYS 2.0 DAYS 2.9 DAYS 3.0 DAYS FUEL OIL CONSUMPTION UNIT # I # I YEAR 2003-04 2004-05 HFO KL 228 243 LDO KL 224 38 TOTAL KL 452 281 # II # II #I 2004-05 2005-06 2005-06 251 148 - 151 141 - 402 289 170 THANK YOU