Campus Units
Agricultural and Biosystems Engineering, Chemical and Biological Engineering, Mechanical Engineering, Bioeconomy Institute (BEI)
Document Type
Article
Publication Version
Accepted Manuscript
Publication Date
9-1-2019
Journal or Book Title
Applied Energy
Volume
249
First Page
276
Last Page
285
DOI
10.1016/j.apenergy.2019.04.154
Abstract
Heat transfer is the bottleneck to fast pyrolysis of biomass. Although the enthalpy for pyrolysis of biomass is relatively small operation at temperatures around 500 °C constrains heat carrier selection to inert gases and granular media that can sustain only modest thermal fluxes in practical pyrolysis systems. With heat transfer controlling the rate of pyrolysis, reactor capacity only scales as the square of reactor diameter and does not benefit from economies of scale in building larger reactors. We have eliminated this heat transfer bottleneck by replacing it with partial oxidation of pyrolysis products to provide the enthalpy for pyrolysis in a fluidized bed reactor, a process that can be described as autothermal pyrolysis. The oxygen-to-biomass equivalence ratio depends upon the kind of biomass being pyrolyzed and the level of parasitic heat losses from the reactor, but under conditions that simulate adiabatic operation, equivalence ratios are around 0.10, compared to 0.20 or higher for autothermal gasifiers. At this low equivalence ratio, there was no significant loss in bio-oil yield when operating the reactor autothermally (64.8 wt%) as compared to conventional pyrolysis (64.4 wt%). Carbon balances indicate that less valuable pyrolysis products (char and aqueous, bio-oil light ends) are consumed via partial oxidative reactions to provide the enthalpy for pyrolysis. While the carbon yields of char and bio-oil light ends decreased by 25.0% and 21.3%, respectively, the most valuable pyrolysis product (bio-oil heavy ends) only decreased 8.0%.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Copyright Owner
Elsevier Ltd.
Copyright Date
2019
Language
en
File Format
application/pdf
Recommended Citation
Polin, Joseph P.; Peterson, Chad A.; Whitmer, Lysle E.; Smith, Ryan G.; and Brown, Robert C., "Process intensification of biomass fast pyrolysis through autothermal operation of a fluidized bed reactor" (2019). Mechanical Engineering Publications. 356.
https://lib.dr.iastate.edu/me_pubs/356
Included in
Bioresource and Agricultural Engineering Commons, Catalysis and Reaction Engineering Commons, Energy Systems Commons, Heat Transfer, Combustion Commons, Process Control and Systems Commons
Comments
This is a manuscript of the article Polin, Joseph P., Chad A. Peterson, Lysle E. Whitmer, Ryan G. Smith, and Robert C. Brown. "Process intensification of biomass fast pyrolysis through autothermal operation of a fluidized bed reactor." Applied Energy 249 (2019): 276-285. DOI: 10.1016/j.apenergy.2019.04.154. Posted with permission.