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ENERGY AUDIT METHODOLOGY FOR FOR TURBINE CYCLE

ENERGY AUDIT METHODOLOGY FOR FOR TURBINE CYCLE. Presented By M.V.Pande Dy.Director NPTI, Nagpur. COAL TO ELECTRICITY PROCESS. STEAM CYCLE FOR 210 MW UNIT. Effect of Increasing Pressure on Available Energy . Effect of Increasing Steam Temperature On Available Energy.

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ENERGY AUDIT METHODOLOGY FOR FOR TURBINE CYCLE

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  1. ENERGY AUDIT METHODOLOGY FOR FORTURBINE CYCLE Presented By M.V.Pande Dy.Director NPTI, Nagpur

  2. COAL TO ELECTRICITY PROCESS

  3. STEAM CYCLE FOR 210 MW UNIT

  4. Effect of Increasing Pressure on Available Energy Effect of Increasing Steam Temperature On Available Energy Effect of Increasing Steam Pressure & Temperature Both on Available Energy EFFECT OF STEAM PARAMETERS P1 P1 P2 P1 P3 P2 T2 T1 T3 T2 T1 H T1 H H S S S

  5. Effect of Changing Reheat Pressure Effect of Changing Reheat Temp. EFFECT OF STEAM PARAMETERS H H S S

  6. THERMAL PROCESS LOSSES

  7. Impact of Turbine Cylinder Efficiency on HR/Output Description Effect on Effect on TG HR KW 1% HPT Efficiency 0.16% 0.3% 1% IPT Efficiency 0.16% 0.16% 1% LPT Efficiency 0.5 % 0.5 % • FOLLOW TEST CODES • ASME PTC - 6 For Steam Turbines • ASME PTC - 4.1 or BS- 845: 1987 for Boilers

  8. 210 MW KWU STEAM TURBINE STEAM & WATER CYCLE

  9. TURBINE CYCLE LOSSES

  10. STEPS INVOLVED IN CONDUCTING THE TURBINE ENERGY AUDIT • Data collection • Observations and Analysis • Exploration for energy conservation measures • Report preparation

  11. DATA COLLECTION • Design Specification of turbine and associated equipment: • Type of the turbine, make and model • Number of cylinders • No of stages (for HP, IP and LP) • No of main and reheat valves • Construction details of HP, IP LP • Turbine extraction systems • Control systems • Type of governing • Type of sealing • Year of installation • Major modifications carried out during the recent past

  12. Turbine Cycle Heat Rate Kcal/kwh DATA COLLECTION

  13. DATA COLLECTION

  14. INSTRUMENTS REQUIRED • Temperature Indicator & Probe • Pressure gauges • Flow measuring instrument (steam and water) • Ultrasonic leak detector

  15. MEASUREMENTS & OBSERVATIONS TO BE MADE • Feed water at Inlet & Outlet of Heaters • Main steam parameters • HP turbine extraction • Hot reheat steam, Cold reheat Steam • IP extraction • IP Exhaust • Condenser back pressure • Cooling water flow and temperatures • Generator output • Barometric pressure • Reheater spray (flow) • Superheater spray (flow) • Feed water (flow) Pressure Temperature Flow

  16. MEASUREMENTS & OBSERVATIONS TO BE MADE • Past performance trends on turbine loading, operation, PLF • Major constraint in achieving the high PLF, load or efficiency • Major renovation and modifications carried out in the recent past • Operational failures leading to inefficient operation • Tripping • Performance of associated equipment (condenser, boiler, etc) • Plant side initiatives to improve the performance and efficiency of the Turbine

  17. TURBINE HR EVALUATION AND EFFICIENCY • Turbine heat rate is defined as the heat input (Kcal) required to generate one unit of Electrical output (KWh). The trials are to establish heat rate (Kcal/kWh) and turbine efficiency under, as run conditions have to be carried out • The efficiency method given in this procedure is the enthalpy drop efficiency method. This method determines the ratio of actual enthalpy drop across turbine section to the isentropic enthalpy drop • This method provides a good measure for monitoring purposes. Each section of the turbine must be considered as a separated turbine • Each section should be tested and results are trended separately. While conducting the tests, it has to be ensured that, it is conducted over normal operating load range

  18. TURBINE HR EVALUATION AND EFFICIENCY Q1 x (H1– h2) + Q2 X (H3 – H2) Gross Generator Output Turbine Heat Rate = 860 Heat Rate kW kCal/hr Turbine Cycle Efficiency = X 100

  19. Actual Process 1-2-3-4-5 Comparison of Actual Expansion with Isentropic Expansion in Turbine Actual Expansion in HP, IP & LP Cylinder TURBINE HR EVALUATION AND EFFICIENCY

  20. Variation of Heat Rate with Load Heat Rate Characteristics with Condenser Exhaust Pressure TURBINE HR EVALUATION AND EFFICIENCY

  21. Kcal/kg/oK TURBINE EFFICIENCY EVALUATION DATA

  22. Effect of Condenser Vacuum on Heat Rate 10 MM HG IMPROVEMENT IN CONDENSER VACUUM LEADS TO 20 Kcal/kwh (1%) IMPROVEMENT IN HEAT RATE FOR A 210 MW UNIT

  23. EFFECT ON HEAT RATE FOR PARAMETER DEVIATION (500 MW UNIT)

  24. IDENTIFYING FACTORS FOR HR DEVIATION After evaluating the turbine heat rate and efficiency, check for the deviation from the design and identify the factors contributing for the deviations. The major factors to be looked into are: • Main steam and reheat steam inlet parameters • Turbine exhaust steam parameters • Reheater and super heater spray • Passing of high energy draining • Loading on the turbine • Boiler loading and boiler performance • Operations and maintenance constraints

  25. IDENTIFYING FACTORS FOR HR DEVIATION • Condenser performance and cooling water parameters • Silica deposition and its impact on the turbine efficiency • Inter stage sealing, balance drum and gland sealing • Sealing fins clearances • Nozzle blocks • Turbine blade erosion • Functioning of the valves • Operational status of HP heaters • Performance of reheaters

  26. FEED WATER HEATERS PERFORMANCE inlet inlet outlet 0 C

  27. FEED WATER HEATERS PERFORMANCE • While collecting the heater wise parameters, collect the following data: • Unit load MW • Main steam pressure, temperature & flow • Feed water flow • Super heater & Reheater attemperation flow • Boiler feed pump discharge pressure • HP Heater levels • Condenser vacuum, Barometric pressure

  28. After the collecting the above data, evaluate the following • Terminal temperature difference – TTD • Heater drain cooler approach temperature difference – DCA • Feed water temperature rise across heater – TR TTD = t sat – t fw outlet FEED WATER HEATERS PERFORMANCE

  29. DCA = t drains– t fw inlet TR = t outlet– t fw inlet FEED WATER HEATERS PERFORMANCE

  30. HEATER PERFORMANCE DEVIATION • Check following if TTD, DCA, TR are deviating from the design and actual rise in feed water temperature is low: High terminal temperature difference, TTD • Excessive venting (worn vents, altered set point, vent malfunctioning) • Excessive make up • High water level (tube leaks, improper setting) • Header partition leaks • Non condensable gases on shell side • Excessive tube bundle pressure drop (excessive number of tubes plugged, tubes folded internally)

  31. HEATER PERFORMANCE DEVIATION • High drain cooler approach temperature, DCA • Drain cooler inlet not submerged • Low drain water level (improper setting, excessive FW heater drain bypass – bypass valve left open - bypass valve malfunctioning / leaking) • Excessive tube bundle pressure drop (excessive number of tubes plugged / tubes folded internally) • Feed water heater bypassed • FW heater bypass valve leaking Note: Similar approach shall be followed for LP Heaters

  32. ADDITIONAL LOAD ON ECONOMIZER economizer Based on the above, if the HP heaters performance is poor, then additional load on economizer can be estimated by using the data sheet

  33. THANK YOU

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