Question

mixture of 35 mole% pentane (C5H12) and 65 mole% butane (C4H10) is burned with 30% excess air in the furnace of a boiler. Fractional conversions of 0.95 for the pentane and 0.90 for the butane are reported. The mole ratio of CO/CO2, in the combustion gases is found to be 0.05. (a) List the major components that will be present in the product gas stream from the process. [5%] (b) Draw and label fully a PFD for this process. [10%] (c) Perform a Degrees of Freedom analysis stating clearly the number of unknown variables and the relationships that you may use to balance the process flow chart. Show that it is necessary to make one further assumption to allow you to balance the PFD. [15%] (d) Write down the combustion equations that are used to determine the excess air requirement and, assuming a basis of 100 mol/min of the pentane/butane feed, determine the molar feed rate of air to the process. [20%] (e) Write down the actual combustion reactions for the process. [10%] (f) Determine the composition of the flue gas on a dry basis. [30%] (g) Determine the mass flow rates of the feed streams and hence determine the mass flow rate of the exit gas stream.

Answer 1