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16-Perfect reasons for more fuel consumption of Boilers

Following are the 16-reasons for increase in Boilers fuel consumption 1. Decreased economiser inlet feed water temperature: On every 6-8 deg C decrease in Economiser inlet feed water temperature causes the rise in Boiler fuel consumption by 1%. 2. Increased Boiler outlet   flue gas   temperature: On every 22 deg C increase in flue gas temperature causes the reduction in Boiler efficiency by 1% & hence boiler fuel consumption increases for generating same steam. 3. Increased moisture content in the fuel Boilers fuel consumption increases as the moisture in the fuel increases. As it requires more excess air & reduces combustion efficiency leading to unburnt losses 4. Increased excess air 10-Tips to reduce LOI in Boilers Increase in excess air causes dry flue gas loss & hence more fuel consumption. And also leads to more auxiliary power consumption. 5. Increased unburnt loss Unburnt fuel or incomplete combustion of fuel leads to increased consumption of fuel.

Calculated reasons for increase in Turbine specific steam consumption

1. Lower vacuum Turbine consumes more steam, if vacuum in condenser is maintained on lower side. Example:   Consider a 20 MW Steam Turbine having Inlet steam parameters 65 kg/cm2 & 490 Deg C & Vacuum maintained in condenser is -0.9 kg/cm2. Calculate the steam consumption of turbine at vacuum -0.9 kg/cm2 & -0.85 kg/cm2 A-Steam consumption Q at -0.9 kg/cm2 to develop 20 MW power P =Steam flow X( Enthalpy of inlet steam-Enthalpy of exhaust steam)/ 860 Enthalpy of inlet steam at inlet steam parameters =810 kcal/kg Exhaust steam enthalpy at -0.9 kg/cm2 vacuum = 619 kcal/kg Then, 20 = Q X (810-619)/860 Q1 = 90 MT B- Steam consumption Q at -0.85 kg/cm2 to develop 20 MW power Exhaust steam enthalpy at -0.85 kg/cm2 vacuum= 623 kcal/kg Then, 20 = Q X (810-623)/860 Q 2= 90.9 MT It is clear that, Turbine operating at -0.9 kg/cm2 vacuum consumes lesser steam as compared to turbine operating at vacuum-0.85 kg/cm2 2. Lower inlet main stream pressure& temp