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ENERGY EFFICIENT O&M PRACTICES FOR BOILER AUXILIARIES

ENERGY EFFICIENT O&M PRACTICES FOR BOILER AUXILIARIES. A.K.SAMAIYAR, Sr.Manager NTPC LIMITED Corporate Operation Services (OS-CC) Boiler Group. PERFORMANCE ASSESSMENT OF BOILERS. BOILER EFFICIENCY CALCULATION. LOSSES IN BOILER: DRY GAS LOSS (Z1) UNBURNT CARBON LOSS (Z2)

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ENERGY EFFICIENT O&M PRACTICES FOR BOILER AUXILIARIES

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  1. ENERGY EFFICIENT O&M PRACTICES FOR BOILER AUXILIARIES A.K.SAMAIYAR, Sr.Manager NTPC LIMITED Corporate Operation Services (OS-CC) Boiler Group

  2. PERFORMANCE ASSESSMENT OF BOILERS

  3. BOILER EFFICIENCY CALCULATION • LOSSES IN BOILER: • DRY GAS LOSS (Z1) • UNBURNT CARBON LOSS (Z2) • MOISTURE IN FUEL LOSS (Z3) • HYDROGEN IN FUEL LOSS (Z4) • LOSS DUE TO CARBON MONOXIDE (Z5) • AIR MOISTURE LOSS (Z6) • OTHER LOSSES (Z7) • RADIATION LOSS (Z8) • LOSS DUE TO MILL REJECTS (Z9) • TOTAL LOSS Z = Z1+Z2+Z3+Z4+Z5+Z6+Z7+Z8+Z9 • BOILER EFF. η = (100-Z)

  4. BOILER EFFICIENCY CALCULATION C = Carbon in fuel S = Sulphur in fuel U = Combustibles in ash Tgo = APH gas out temp. Ta = Ambiant temp. • DRY GAS LOSS (Z1): Wd = (C + S/2.67 – 100*U)/12/CO2 Sh= Wd*30.6*(Tgo-Ta) Z1 = Sh * 100/Gcv/4.186

  5. BOILER EFFICIENCY CALCULATION Ambient Temp. FG temp. at APH outlet M6 18.74oC 131.99oC B6 19.26oC 130.45oC

  6. RE-GENERATIVE AIR PREHEATER

  7. Factors affecting the performance of APHs • Condition of heating elements • Condition of seals /seal setting • Condition of sector plates / axial seal plates • Condition of Diaphragm plates • Condition of Casing / enclosure • Condition of Insulation

  8. Operation problems HIGHER PRESSURE DROP ACROSS APH • Choking of heating elements • Higher flows • Eroded/damaged heating elements - obstructs flow path. • Improper steam parameters and eroded nozzles and steam pipes. • Low cold end average temperature.

  9. Operation problems HIGH GAS LEAVING TEMPERATURES • More gas flow with high inlet temperature temp. • Less air flow and high inlet temp. • Choking of SCAPH – less air flow • Choking of heating elements • Erosion & corrosion of heating elements

  10. Operation problems CHOKING OF HEATING ELEMENTS • Improper evacuation of economiser hopper. • Corrosion of heating elements • Boiler slagging • Improper drying of heating elements after water washing. • Excess air operation. • Leak in SCAPH and water washing & deluge line, soot blower passing etc. • Frequent water washing of heating elements and improper drying. • Proper exit gas temperature with respect to % of sulphur in fuel.

  11. Pit Head Station Rail Fed Station 210 MW 500 MW 210 MW 500 MW 1% Overall Heat Rate Improvement ( from 2500 kcal / kWh) 55.18 Lacs 131.4 Lacs 147 Lacs 350 Lacs 1 Deg C change in APH Exit Gas Temperature 2.64 Lacs 6.30 Lacs 7.06 Lacs 16.82 Lacs Typical savings from Heat Rate Improvement ( Rs / Year)

  12. CURRENT MAINTENANCE PRACTICES • Hot washing of baskets after shut down • High Pressure water jet cleaning of baskets • Basket replacement based on • Weighment • Physical condition • Trending of air / gas side efficiency • Covering of cleaned baskets with templates

  13. CURRENT MAINTENANCE PRACTICES • Replacement of all Sealing elements based on condition assessment • Replacement of Sector Plates based on condition assessment • Inspection and repair of diaphragms by grafting new plate • Inspection and repair / replacement of HE supports , CE grills

  14. CURRENT MAINTENANCE PRACTICES • Seal setting as per OEM manual / site experience • Leveling of Rotor , Sector Plate for restricting inter-sector leakage • Wear debris analysis of lube-oil on a quarterly basis • Inspection of Guide bearing during every OH • Leveling of bearings

  15. CURRENT MAINTENANCE PRACTICES • Servicing of Drive System • Inspection and maintenance of : • FG duct, Supports and Dampers at inlet and outlet • Soot Blower • Fire fighting / water washing manifolds

  16. Soot Blowers • Soot blower travel to be set to ensure full coverage of all the heating element • Thermal drain at soot blowing steam line. • Operation at rated steam pressure and temperature • Modifications may be done to provide super heated steam during start ups.

  17. Whatever is ignored during operation adds to the woes of maintenanceOperation & Maintenance practices overlap & influence each other.

  18. To Conclude..… • Energy conservation is a continuing process. • It must be a part of normal work activities • It requires active involvement of one and all • It must have the full support of top management

  19. THANK YOU

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