11
Table 2 Characteristics of
slow, intermediate and fast
pyrolysis [52, 57]
Process
Conditions
Slow
Solid residence time (h/days),
~290–400 °C
Intermediate Solid residence time (min), ~400 °C
Fast
Solid residence time (s), ~500 °C
80
35
25
12
20
35
25
13
20
25
15
10
25
60
0
20
40
60
80
100
)
%
t
w
(
t
c
u
d
o
r
P
Bio-oil
Water
Gas
Char
Fig. 4 Different products
from biomass pyrolysis.
(Reproduced with
permission from [57],
Copyright © 2012,
Elsevier)
5 Fundamentals of Slow, Intermediate and Fast Pyrolysis
Typically, slow pyrolysis is a batch system despite the existence of a few works
using the continuous process [60, 61]. It involves slow heating rates, low temperatures (normally below 300 °C) and long residence time, and the biochar is the primary bio-product [62]. The majority of the slow pyrolysis works are oriented for
biochar formation and utilization; however, the liquids and gases can also be used
as a fuel at the production site [63]. In addition, the high amount of acetic acid and
other acid compounds in the oil make this pyrolysis liquid suitable for pesticide
applications [64]. This process can tolerate water present in the biomass, which has
a straight effect on biochar properties, promoting the formation of activated carbon
[65]. For biochar production, moisture content between 15% and 20% is the usual
range [62]. The feedstock particle size can differ from wood logs to pellets. Wood is
the most common biomass for slow pyrolysis, and this process can work with rice
straw, palm, bamboo, sugarcane bagasse and nutshells [66, 67].
Carbonization is the oldest method for biomass processing and consequent char
production, where the solid residue is the desirable product [65]. Slow pyrolysis
products without condensation of the vapours can be utilized to deliver heat to the
Thermochemical Conversion of Biomass and Upgrading of Bio-Products to Produce…
Table 2 Characteristics of
slow, intermediate and fast
pyrolysis [52, 57]
Process
Conditions
Slow
Solid residence time (h/days),
~290–400 °C
Intermediate Solid residence time (min), ~400 °C
Fast
Solid residence time (s), ~500 °C
80
35
25
12
20
35
25
13
20
25
15
10
25
60
0
20
40
60
80
100
)
%
t
w
(
t
c
u
d
o
r
P
Bio-oil
Water
Gas
Char
Fig. 4 Different products
from biomass pyrolysis.
(Reproduced with
permission from [57],
Copyright © 2012,
Elsevier)
5 Fundamentals of Slow, Intermediate and Fast Pyrolysis
Typically, slow pyrolysis is a batch system despite the existence of a few works
using the continuous process [60, 61]. It involves slow heating rates, low temperatures (normally below 300 °C) and long residence time, and the biochar is the primary bio-product [62]. The majority of the slow pyrolysis works are oriented for
biochar formation and utilization; however, the liquids and gases can also be used
as a fuel at the production site [63]. In addition, the high amount of acetic acid and
other acid compounds in the oil make this pyrolysis liquid suitable for pesticide
applications [64]. This process can tolerate water present in the biomass, which has
a straight effect on biochar properties, promoting the formation of activated carbon
[65]. For biochar production, moisture content between 15% and 20% is the usual
range [62]. The feedstock particle size can differ from wood logs to pellets. Wood is
the most common biomass for slow pyrolysis, and this process can work with rice
straw, palm, bamboo, sugarcane bagasse and nutshells [66, 67].
Carbonization is the oldest method for biomass processing and consequent char
production, where the solid residue is the desirable product [65]. Slow pyrolysis
products without condensation of the vapours can be utilized to deliver heat to the
Thermochemical Conversion of Biomass and Upgrading of Bio-Products to Produce…