Question
Download Solution PDFIn a steam boiler, the actual evaporation is 8 kg of steam per kg of fuel burnt. The heat supplied per kg of water is 2500 kJ/kg. Higher calorific value of fuel is 25,000 kJ/kg. What is the boiler efficiency?
Answer (Detailed Solution Below)
Detailed Solution
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Boiler efficiency (η) is given by the ratio of heat absorbed by the water or steam to the heat supplied by the fuel. Using the definition, boiler efficiency can be calculated as follows:
η = (Heat absorbed by water or steam / Heat supplied by the fuel)
The heat absorbed by water or steam is equal to the actual evaporation multiplied by the heat supplied per kg of water.
Calculation:
Given:
The actual evaporation is 8 kg of steam per kg of fuel burnt and the heat supplied per kg of water is 2500 kJ/kg.
So, Heat absorbed by water = actual evaporation * heat supplied per kg of water, which is 8 kg/kg × 2500 kJ/kg = 20000 kJ/kg of fuel
The heat supplied by the fuel is the higher calorific value of the fuel, which is given as 25000 kJ/kg.
So, the boiler efficiency η = 20000 kJ/kg / 25000 kJ/kg = 0.80 or 80%
Last updated on May 28, 2025
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