Primairy fast pyrolysis products from pine-wood

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Primairy fast pyrolysis products from pine-wood

• A comparison between wire mesh and fluidized bed
  pyrolysis

Elly Hoekstra, Roel Westerhof and Kees Hogendoorn
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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
Aim
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Wire-Mesh reactor
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Set-up
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Operating conditions
Heating rate 7000 0C/s
Temperature Uniformity Mesh 35 0C
Temperature Fluctuations 5 0C
Vapor residence time lt 15 ms
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Set-up
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Movies
Vacuum and Cooling
Atmospheric without Cooling
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Set-up
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Primary versus Secondary Yields
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Primary
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Primary versus Secondary Mw-distribution
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Primary
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Primary versus Secondary SEM
melting/evaporation
physical entrainment
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Primary
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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
Conversion Rate Biomass Loading
Temperature Conclusions
..Primary
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Primary fast pyrolysis processes

• High oil yields (gt 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
Conversion Rate Biomass Loading
Temperature Conclusions
..Primary
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Effect holding time yields
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Conversion Rate
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Effect holding time gas and char composition
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Conversion Rate
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Experimental progress Grey Intensity Method
Experimental Progress
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Conversion Rate
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Conversion rate experimental progress
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
Conversion Rate
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Comparison with C. Di Blasi and C. Branca 2001
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
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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
Conversion Rate
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Biomass loading
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 Loading
Temperature Conclusions
..Biomass Loading
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Temperature yields
Wire-Mesh reactor
Pilot Plant
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Temperature
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Temperature gas composition
Wire-Mesh reactor
Pilot Plant
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Temperature
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Temperature Mw-distribution
Wire-Mesh reactor
Pilot Plant
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Temperature
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Temperature Mw-distribution
Wire-Mesh reactor
Pilot Plant
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Temperature
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Temperature Mw-distribution
Wire-Mesh reactor
Pilot Plant
Aim Set-up Primary
Conversion Rate Biomass Loading
Temperature Conclusions
..Temperature
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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 Conclusions
..Temperature
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Conclusions

• Primary pyrolysis compared to conventional
  pyrolysis
• High oil yields (gt 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