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Primairy fast pyrolysis products from pine-wood
A comparison between wire mesh and fluidized bed pyrolysis
24/04/2020
Elly Hoekstra, Roel Westerhof
Title: to modify choose 'View' then
'Heater
and footer'
and Kees
Hogendoorn
1
Aim
Study the primary pyrolysis processes and to clarify the
primary reaction mechanisms.
By understanding of the primary fast pyrolysis
mechanism it may be possible to develop methods to
steer the final pyrolysis oil composition.
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Wire-Mesh reactor
5
1
2
3
4
5
Mesh/wood sample
Vessel
Vacuum pump
Liquid nitrogen bath
Syringe
1
2
4
3
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Operating conditions
600
holding time
7000 0C/s
Heating rate
Temperature Uniformity Mesh
± 35 0C
Temperature Fluctuations
± 5 0C
Vapor residence time
< 15 ms
500
T [0C]
400
300
200
100
0
0
Aim
Set-up
3
Primary
Conversion Rate
Time [s]
Biomass Loading
6
9
Temperature
Conclusions
Movies
Vacuum and Cooling
Aim
Set-up
Primary
Conversion Rate
Atmospheric without Cooling
Biomass Loading
Temperature
Conclusions
Primary versus Secondary: Yields
Oil
Gas
Char
Yield [wt%]
100
75
50
25
0
Pvac Patm No
Cooling cooling
Aim
Set-up
..Primary
Primary
Conversion Rate
Pilot
Plant
Biomass Loading
Temperature
Conclusions
Primary versus Secondary: Mw-distribution
2,5
Pilot Plant
Patm No Cooling
Pvac Cooling
W(logM)
2,0
1,5
1,0
0,5
0,0
100
Aim
Set-up
..Primary
Primary
1000
M [g/mol]
Conversion Rate
Biomass Loading
10000
Temperature
Conclusions
Primary versus Secondary: SEM
melting/evaporation
Aim
Set-up
..Primary
Primary
Conversion Rate
physical entrainment
Biomass Loading
Temperature
Conclusions
Primary versus Secondary: sugars
Observation:
A THF insoluble fraction but water soluble fraction was
observed for the experiments carried out using vacuum
and cooling
HPLC Analyses (RUG)
This fraction contained mainly sugars
Model compound study: glucose and levoglucosan
These compounds were evaporated and condensed
without reactions taken place
Aim
Set-up
..Primary
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Primary fast pyrolysis processes:
 High oil yields (> 80 wt%)
 Extremely low char yields (~ 5 wt%)
 Presence of high molecular weight products
 Presence of sugars
 Less alkane like groups (NMR)
Aim
Set-up
..Primary
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Effect holding time: yields
100
Yield [wt%]
Oil
80
60
40
20
Gas
Char
0
0
Aim
Set-up
1
2
holding time [s]
Primary
Conversion
ConversionRate
Rate
Biomass
BiomassLoading
Loading
3
Temperature
Temperature
Conclusions
Conclusions
Effect holding time: gas and char composition
60
Pine Wood
CO
0s
40
1s
20
3s
CH4
HH
0
0
Aim
Set-up
1
2
Holding time [s]
Primary
3
Conversion Rate
3500
2500
1500
-1
Wavenumber [cm ]
Biomass Loading
Temperature
Transmittance [%]
mol%
CO2
500
Conclusions
Experimental progress: “Grey Intensity Method”
Experimental Progress
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Conversion rate: experimental progress
Grey Intensity [-]
1
Reactions approximately completed
0,8
0,6
0,4
0,2
0
0
Aim
Set-up
Primary
1
Conversion Rate
Time [s]
Biomass Loading
2
Temperature
3
Conclusions
Comparison with C. Di Blasi and C. Branca [2001]*
100
Reactions approximately completed
Yield [wt%]
80
Oil
60
40
20
Gas
0
0
Char
1
2
Holding time [s]
3
Colomba Di Blasi* and Carmen Branca, Kinetics of Primary Product Formation from Wood Pyrolysis, Ind. Eng. Chem. Res. 2001, 40, 5547-5556
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Conversion rate
 The majority of the reactions in our wire-mesh reactor
was finished within 0.5 s.
 Our results indicate that the actual primary pyrolysis
process is faster than previously thought
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
Conclusions
Biomass loading
80
100
CO
60
60
mol%
Yield [wt%]
80
Oil
40
20
40
CO2
20
Gas
CH4
Char
0
0,04
0,06
0,08
m [g]
0,10
0
0,04
HH
0,06
0,08
m [g]
0,10
Although the absolute biomass was small, the results are still influenced
by secondary reactions, the extent is increasing with biomass loading.
Aim
Set-up
Primary
Conversion Rate
..Biomass
Biomass Loading
Temperature
Conclusions
Temperature: yields
100
Char
100
Oil
80
Yield [wt%]
Yield [wt%]
80
60
40
Gas
20
Oil
60
40
Char
20
0
200
400
600
0
T [ C]
800
0
200
Wire-Mesh reactor
Aim
Gas
Set-up
Primary
Conversion Rate
400
600
0
T [ C]
800
Pilot Plant
Biomass Loading
..Temperature
Temperature
Conclusions
Temperature: gas composition
100
100
80
80
CO
60
mol %
mol %
CO2
40
20
0
200
HH
400
0
600
800
40
0
200
T [ C]
Set-up
Primary
Conversion Rate
CH4
HH
400
0
600
800
T [ C]
Wire-Mesh reactor
Aim
CO
60
20
CH4
CO2
Pilot Plant
Biomass Loading
..Temperature
Temperature
Conclusions
Temperature: Mw-distribution
4500C
1,6
2,4
3250C
1,8
W(logM)
W(logM)
1,2
0,8
0,4
700 C
1000
M [g/mol]
1,2
5300C
0,6
0
0,0
100
5800C
10000
0,0
100
Wire-Mesh reactor
Aim
Set-up
Primary
Conversion Rate
0
360 C
1000
10000
M [g/mol]
100000
Pilot Plant
Biomass Loading
..Temperature
Temperature
Conclusions
Temperature: Mw-distribution
4500C
1,6
2,4
3250C
1,8
W(logM)
W(logM)
1,2
0,8
0,4
700 C
1000
M [g/mol]
1,2
5300C
0,6
0
0,0
100
5800C
10000
0,0
100
Wire-Mesh reactor
Aim
Set-up
Primary
Conversion Rate
0
360 C
1000
10000
M [g/mol]
100000
Pilot Plant
Biomass Loading
..Temperature
Temperature
Conclusions
Temperature: Mw-distribution
4500C
1,6
2,4
3250C
1,8
W(logM)
W(logM)
1,2
0,8
0,4
700 C
1000
M [g/mol]
1,2
5300C
0,6
0
0,0
100
5800C
10000
0,0
100
Wire-Mesh reactor
Aim
Set-up
Primary
Conversion Rate
0
360 C
1000
10000
M [g/mol]
100000
Pilot Plant
Biomass Loading
..Temperature
Temperature
Conclusions
Temperature
 Decrease in oil yield
 Still cracking reactions possible under the extreme conditions in our set-up
 However the yield is still above 60 wt% at 700 0C
 Heavier products formed at higher temperatures
 Heavier molecules can evaporate at higher temperatures
 Cracking is minimized inside the wire-mesh reactor
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
..Temperature
Temperature
Conclusions
Conclusions
Primary pyrolysis compared to conventional pyrolysis
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



High oil yields (> 80 wt%) and extremely low char yields (~ 5 wt%)
Less alkane like groups (NMR)
High molecular weight products and sugars
Heavier products formed at higher temperatures
Extremely fast conversion rate
However, secondary cracking reactions are extremely fast
 Inside biomass layer
 At high temperatures
Aim
Set-up
Primary
Conversion Rate
Biomass Loading
Temperature
..Conclusions
Conclusions