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Title: Process intensification of biomass fast pyrolysis through autothermal operation of a fluidized bed reactor

Journal Article · · Applied Energy

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. Here, 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%.

Research Organization:
RAPID Manufacturing Institute, New York, NY (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Energy Efficiency Office. Advanced Manufacturing Office
Grant/Contract Number:
EE0007888
OSTI ID:
1642390
Journal Information:
Applied Energy, Vol. 249, Issue C; ISSN 0306-2619
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 62 works
Citation information provided by
Web of Science

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Cited By (2)

Production and purification of crystallized levoglucosan from pyrolysis of lignocellulosic biomass journal January 2019
Negative Emission Energy Production Technologies: A Techno‐Economic and Life Cycle Analyses Review journal October 2019

Figures / Tables (15)