Question

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 25ºC, 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 90ºC. 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:

(CV) per m3 of the fuel/air mix i have 108.135 MJ/m3

(CV) per kmol of the fuel/air mix i have 2456.51 MJ/Kmol

on a wet basis i have CO2 - 11.07%, N2 - 73.68%, O2 - 1.78%, H2O - 13.48%

on a dry basis. CO2 - 12.79%, N2 - 85.15%, O2 - 2.06%

(f) Determine the ‘furnace efficiency’ if the flue gases leave the boiler at300ºC.

Data: Net calorific value (MJ/m3 ) at 25ºC of:

Butane (C4H10) = 111.7 MJ/m3

Butene (C4H8) = 105.2 MJ/m3

Propane (C3H8) = 85.8 MJ/m3

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.

Please write as clearly as possible so i can read what is put or typed would be even better. Please go through the answer as thoroughly as you can too. Please only provide and answer for furnace efficiency.

Answer 1

comment if any doubt.