A gaseous fuel made up of methane and ethane is burned with enriched air that contains 50% oxygen dan 50% nitrogen by mole. The flue gas analysis on a dry basis is 25 mol% CO2, 15 mol% O2 and the balance is nitrogen. Use 100 mol/s of dry flue gas as the basis of calculation.

a) Draw a completely labelled diagram of the process. (3 marks)

b) Write the balanced stoichiometric equations for the combustions of methane and ethane. (2 marks)

c) Using the reactive material balance, calculate all unknown flowrates and the mole percent of methane in the fuel. (9 marks)

d) Determine the percent excess air. (4 marks)