N-butane is a hydrocarbon and is highly flammable, colourless, odourless, easily liquified gas. As well as often found in process industry it is best known as a good combustion fuel. If you have 1000mol/h n-butane and 500mol/h of air fed into the combustion reactor.

a) Write the stoichiometric reaction (2marks)

b) Calculate the excess air in % that is used in the combustion chamber (5marks)

c) How much more energy, as an enthalpy increase, can be extracted from the reaction? (3 marks)

d) How would the excess air used, affect the theoretical adiabatic flame temperature? (2 marks)

e) Assume a typical fuel storage tank is 30m^3, containing 14m^3 of n-butane of liquid phase in equilibrium with n-butane vapour at 25C. What is the mass of the vapour in the tank? (13 marks)

Data to use:

The vapour pressure of n-butane at 25C is 2.43 bar.

n-butane (58g/mol): Tc= 425.1K, Pc = 37.96 bar, w= 0.197

Z=PVm/RT = 1+ (B0+wB1)Pr/Tr B0=0.083-0.422/T^1.6 B1 = 0.139-0.172/T^4.2