A steam generator comprises a boiler, a superheater, an economizer, and an air preheater. The feedwater enters the economizer at 140 oC and leaves the boiler drum at 60 bar, 0.98 dries, and leaves the superheater at 450 oC. When using coal with a calorific value of 25.2 MJ/kg, the rate of evaporation is 8.5 kg steam per kg coal and the air-fuel ratio is 15:1 by mass. Neglecting heat losses and pressure drops, estimate the heat transfer per kg fuel in each component and the efficiency of the steam generator. What are the percentages of the total heat absorption taking place in the economizer, boiler, and superheater, respectively? Assume Cp of air and water as 1.005 and 4.2 kJ/kg-K, respectively.
A steam generator comprises a boiler, a superheater, an economizer, and an air preheater. The feedwater enters the economizer at 140 oC and leaves the boiler drum at 60 bar, 0.98 dries, and leaves the superheater at 450 oC. When using coal with a calorific value of 25.2 MJ/kg, the rate of evaporation is 8.5 kg steam per kg coal and the air-fuel ratio is 15:1 by mass. Neglecting heat losses and pressure drops, estimate the heat transfer per kg fuel in each component and the efficiency of the steam generator. What are the percentages of the total heat absorption taking place in the economizer, boiler, and superheater, respectively? Assume Cp of air and water as 1.005 and 4.2 kJ/kg-K, respectively.
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