Challenges Rising fuel costs which in most ofpower generating companies arepassed through to customer ,caughtthe attention to regulating agencies. Regulating agencies are now payingmore attention to efficiency of powerplants.
Heat Rate Definitions Heat rate is defined in units ofkJ/kWh and is simply the amount ofheat input into a system divided bythe amount of power generated by asystem. Less heat rate (less fuel) means moreefficient system.
BENEFIT -identification of losses Efficiency increase Green house gases emission decrease Particulate emission reduction Availability improvement Reduction in O&M cost Less capacity addition Increase profitability
Steam Turbine losses Symptoms HP/IP/LP section efficiency less thandesign. Causes (any one or more than one) Change in internal conditions of turbine 1.Mechanical damages 2.Flow area decreases 3.Flow area bypass 4.Flow area increases Change in inlet conditions
1.MECHANICAL DAMAGES Symptoms Sudden change in section efficiency. Sudden change in section pressure ratio. Cause Metallurgical defects. Maintenance practice.
2.FLOW AREA DECREASE Symptoms Increase in pressure ratio Decrease in section efficiency Increase in up stream pressure cause Mechanical blockage Sudden increase in pressure ratio Sudden decrease in section efficiency Sudden increase in up stream pressure Blade deposits Gradual increase in pressure ratio Gradual decrease in section efficiency Gradual increase in upstream pressure
3.FLOW AREA BYPASS Symptoms Decrease in section efficiency Decrease in pressure ratio Decrease in upstream pressure Cause Hp turbine bushing leakage Main steam stop valve leakage HP gland seal leakage IP stop/intercept valve leakage IP turbine bushing leakage
4.Flow area increase Symptoms Decrease in pressure ratio Decrease in section efficiency Decrease in upstream pressure Cause Spill strip or packing leakage Erosion of turbine stages Solid particle erosion of nozzle block Blade mechanical damage
Spill strip or packing leakage Symptoms Increased down stream extraction temperatures Sudden decrease in stage efficiency Cause Thermal stress Rubbing Vibration Operating procedures
Solid particle erosion of nozzleblocks Symptoms Increase in pressure down stream of firststage Increase in ratio of first stage to throttle pressure Cause Cycling Exfoliation in boiler tubes1. Condenser tube leak2. Poor water chemistry
Erosion of turbine stages Symptoms Gradual decrease in pressure ratio Gradual decrease in section efficiency Gradual decrease in upstreampressure
Blade mechanical damages Symptoms Sudden decrease in pressure ratio Sudden decrease in section efficiency Sudden decrease in upstreampressure.
Cross section of turbine –showingefficiency loss due to leakageLeaking steam notcontribution to powergeneration (in RED)
HP CYLINDER EFFICIENCYKWU TURBINE 210 MWS.N DESCRIPTION UNIT DESIGN OPERATING1 POWER OUTPUT MW2102102 INLET PRESS TO HP CYLINDER KG/CM2 150 139.73INLET TEMP TO HP CYLINDER DEG C 535 537.84OUTLET PRESS FROM HPCYLINDERKG/CM2 38.1 38.95OUTLET TEMP FROM HPCYLINDERTEMP 334.8 361.36ENTHALPY OF INLET STEAM KCAL/KG 814.73 819.257ISENTROPIC ENTHALPY AFTER EXPANSION KCAL/KG 719.95 728.778ACTUAL ENTHALPY AFTER EXPANSION KCAL/KG 730.88 746.159 CYLINDER EFFICIENCY% 88.4780.9INCREASED