Page 116 - Chemical engineering design

96
Reactions: C C O 2 ! CO 2
1
H 2 C O 2 ! H 2 O CHEMICAL ENGINEERING
2
Element kg kmol Stoichiometric O 2 kmol, products
kmol
C 87.5 7.29 7.29 7.29, CO 2
H 2 8.0 4.0 2.0 4.0, H 2 O
O 2 3.5 0.11 0.11
N 2 1.0 0.04 0.04
Total 11.44 9.29

O 2 required with 20 per cent excess D 9.29 ð 1.2 D 11.15 kmol.
Unreacted O 2 from combustion air D 11.15 9.29 D 1.86 kmol.
79
N 2 with combustion air D 11.15 ð D 41.94 kmol.
21
Composition of combustion gases:
D 7.29 kmol
CO 2
H 2 O D 4.0
0.11 C 1.86 D 1.97
O 2
0.04 C 41.94 D 41.98
N 2
Presentation of data to the program:
C p of fuel (component 5), taken as constant,
A D 1.6, B D C D D D 0

Heat of reaction and latent heat, taken to be values at datum temperature of 298 K.
There is no need to convert to kJ/kmol, providing quantities are expressed in kg. For
the purposes of this example the dissociation of CO 2 and H 2 O at 1500 K is ignored.

Computer print-out
Data inputs shown after the symbol (?)
RUN
HEAT BALANCE PROGRAM, BASIS kmol/h, TEMP K, DATUM 298 K
INPUT THE NUMBER OF COMPONENTS, MAXIMUM 10
?5
INPUT HEAT CAPACITY DATA FOR EQUATION A+BT+CT^2+DT^3
FOR COMPONENT 1 INPUT A, B, C, D, INCLUDING ANY ZERO VALUES
? 19.763, 7.332E-2, -5.518E-5, 1.7125E-8
FOR COMPONENT 2 INPUT A, B, C, D, INCLUDING ANY ZERO VALUES
? 32.19, 1.9207E-3, 1.0538E-5, -3.591E-9
FOR COMPONENT 3 INPUT A, B, C, D, INCLUDING ANY ZERO VALUES
? 28.06, -3.67E-6, 1.74E-5, -1.0634E-8
FOR COMPONENT 4 INPUT A, B, C, D, INCLUDING ANY ZERO VALUES
? 31.099, -1.354E-2, 2.6752E-5, -1.1662E-8
FOR COMPONENT 5 INPUT A, B, C, D, INCLUDING ANY ZERO VALUES
?1.6,00, 0,0