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Hi , Please could you answer parts d , e and f of the below question and explain and expand all working so that it

Hi, Please could you answer parts d, e and f of the below question and explain and expand all working so that it is clearly visable in step by step format and the steps explained where necessary for further clarification.
Thankyou in advance for your help.
A fuel gas consists of 75% butane (C4H10),10% propane (C3H8) and 15%
butene (C4H8) by volume.
It is to be fed to the combustion chamber in 10% excess air at 25C, where
it is completely burnt to carbon dioxide and water. The flue gases
produced are to be used to generate 5 bar steam from water at 90C.
With the aid of the data at the end of the question, steam tables and the
enthalpy table given in the Appendix of lesson HTC -4-2 :
(a) Write balanced equations for the combustion of each component of the
fuel gas.
(b) Explain the need for excess air.
(c) Determine the actual fuel:air ratio
(i) by volume (ii) by mass.
(d) Calculate:
(i) the net calorific value (CV) per m3 of the
fuel/air mix at 25C(ii) the net calorific
value (CV) per kmol of the fuel/air mix at
25C.
(e) Determine the composition of the flue gases by volume (assuming the inlet air is dry):
(i) on a wet basis
(ii) on a dry basis.
(f) Determine the 'furnace efficiency' if the flue gases leave the boiler
at 300C.
(g) Give two advantages of preheating the water in this way and one
disadvantage.
(h) Give two reasons why the presence of any sulphur in the fuel mix
would be undesirable.
Data:
Net calorific value (MJm-3) at 25C of:
Butane (C4H10)=111.7MJm-3
Butene (C4H8)=105.2MJm-3
Propane (C3H8)=85.8MJm-3
Air is 21% oxygen, 79% nitrogen by volume and 23.3% oxygen and
76.7% nitrogen by mass.
Atomic mass of C=12,O=16,N=14 and H=1.
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