Biomedical Engineering Reference
In-Depth Information
Typical Gasification Reactions at 25
C
TABLE 7.2
Reaction Type
Reaction
Carbon Reactions
172 kJ/mol
a
R1 (Boudouard)
C
CO
2
2
2CO
1
1
131 kJ/mol
b
R2 (water
gas or steam)
C
H
2
O
2
CO
H
2
1
1
1
74.8 kJ/mol
b
R3 (hydrogasification)
C
2H
2
2
CH
4
2
1
111 kJ/mol
a
R4
C
0.5 O
2
-
CO
1
2
Oxidation Reactions
394 kJ/mol
b
R5
C
1
O
2
-
CO
2
2
284 kJ/mol
c
R6
CO
1
0.5O
2
-
CO
2
2
803 kJ/mol
d
R7
CH
4
1
2O
2
2
CO
2
1
2H
2
O
2
242 kJ/mol
c
R8
H
2
1
0.5 O
2
-
H
2
O
2
Shift Reaction
41.2 kJ/mol
c
R9
CO
H
2
O
2
CO
2
1
H
2
2
1
Methanation Reactions
247 kJ/mol
c
R10
2CO
2H
2
-
CH
4
CO
2
1
1
2
206 kJ/mol
c
R11
CO
3H
2
2
CH
4
H
2
O
1
1
2
165 kJ/mol
b
R14
CO
2
1
4H
2
-
CH
4
1
2H
2
O
2
Steam-Reforming Reactions
206 kJ/mol
d
R12
CH
4
1
H
2
O
2
CO
3H
2
1
1
36 kJ/mol
d
R13
CH
4
1
0.5O
2
-
CO
2H
2
2
1
a
Higman and van der Burgt (2008), p. 12.
b
Klass (1998), p. 276.
c
Knoef (2005), p. 15.
d
Higman and van der Burgt (2008), p. 3.
energy applications. While we cannot do much about the inherent moisture
residing within the cell structure, efforts may be made to drive away the
external or surface moisture. A certain amount of predrying is thus necessary
to remove as much moisture from the biomass as possible before it is fed
into the gasifier. For the production of a fuel gas with a reasonably high
heating value, most gasification systems use dry biomass with a moisture
content of 10
20%.
The final drying takes place after the feed enters the gasifier, where it
receives heat from the hot zone downstream. This heat preheats the feed and
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