Question

Combustion problem :
In a particular combustion chamber butane (C4H10) is used as fuel. It is found that the conversion of the butane (X) is linearly related to the % excess air (E), in the range of 0 to 100% excess, by the following relationship:
X (%) = 80 + E (%) / 5

Answer 1

Where X is the fractional butane conversion, expressed in %, and E is the % excess air.
Thus a feed with 50% excess air would result in a butane conversion of 90%.
For a basis butane feed rate of 100 mol/s, and 25% excess air, determine the flowrate and composition of the stack gases produced from combustion, the energy released and the ratio of kg CO2 /MJ of energy released. For butane, the energy released from combustion is about 2880 kJ/mol. The molar mass of CO2 is 44 g/mol.

Answer 2

Set up a spreadsheet solution in which you can vary the % excess air (using a scroll bar) to see the product stream composition, flowrate and other results. Write a VBA macro to copy and paste key results in order to create a table showing the excess air, the butane conversion, the % CO2 in the stack gas and the kg CO2 /MJ of energy released. Develop a plot showing the CO2 mole fraction and the ratio of kg CO2 to MJ of energy.
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