In a boiler, feed water supplied per hour is 205 kg while coal fired per hour is 23 kg. The net enthalpy rise per kg of water is 145 kJ. If the calorific valve of the coal is 2050 kJ/kg, then the boiler efficiency will be
A. 56%
B. 63%
C. 74%
D. 78%
Answer: Option B
This Question Belongs to Mechanical Engineering >> Steam Boilers, Engines, Nozzles And Turbines
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Boiler efficiency = ms (h - hfi )/mf X C,
= 205 (145)/23 X 2050,
= 0.63,
= 63%.