he fuel gas fed to the furnace. Calculate the molar composition and total molar flow rate of the stack gas. b) Taking as a basis of calculation 100.0 mol of the fuel gas fed to the furnace, calculate the amount (magnitude) of heat (MJ) that must be transferred from t
A fuel gas containing 85.0 mole% methane and the balance ethane is burned completely with
25.0% excess air. The stack gas leaves the furnace at 900.0°C and is cooled to 350.0°C in
a waste-heat boiler, a heat exchanger in which heat lost by cooling gases is used to produce
steam from liquid water for heating, power generation, or process applications.
a) Take as a basis 100.0 mol of the fuel gas fed to the furnace. Calculate the molar
composition and total molar flow rate of the stack gas.
b) Taking as a basis of calculation 100.0 mol of the fuel gas fed to the furnace, calculate the
amount (magnitude) of heat (MJ) that must be transferred from the gas in the waste heat
boiler to accomplish the indicated cooling.
c) How much saturated steam at 50.0 bar can be produced from boiler feedwater at 40.0°C
for the same basis of calculation? (Assume all the heat transferred from the gas goes into
the steam production).
d) At what rate (mol/s) must fuel gas be burned to produce 1280.0 kg/h of saturated steam
(an amount required elsewhere in the plant) in the waste-heat boiler?
e) How does the waste-heat boiler contribute to the plant profitability and environmental
sustainability?
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