Biomedical Engineering Reference
In-Depth Information
110
14
350
300
100
12
250
90
10
200
80
8
150
70
6
100
60
4
50
0
50
2
0
200
400
600
800
1000
Temperature (°C)
Carbon recovery
pH
CEC
Surface area
FIGURE 5.10
A qualitative diagram showing changes in properties of biochar with temperature
of its production. Source: Drawn after Lehman et al. (2007). Higher than 100% carbon recovery
below 200
C is likely to be an experimental error of the authors.
rise to 60% of the initial carbon, but it is less influenced above 600
C.
These suggests that pyrolysis at higher temperature is desirable from a bio-
char production standpoint.
SYMBOLS AND NOMENCLATURE
A
preexponential factor (s
1
)
E
activation energy (J/mol)
reaction rate (s
1
)
k
m
b
mass of biomass at time t (kg)
m
c
mass of char residue (kg)
m
0
initial mass of biomass (kg)
R
universal gas constant (J/mol K)
T
temperature (K)
T
pyr
pyrolysis temperature (K)
t
time (s)
t
heating
heating time (s)
t
r
reaction time (s)
X
fractional change in mass of biomass
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