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Title: Coupling DAEM and CFD for simulating biomass fast pyrolysis in fluidized beds

Abstract

We report results from computational simulations of an experimental, lab-scale bubbling bed biomass pyrolysis reactor that include a distributed activation energy model (DAEM) for the kinetics. In this study, we utilized multiphase computational fluid dynamics (CFD) to account for the turbulent hydrodynamics, and this was combined with the DAEM kinetics in a multi-component, multi-step reaction network. Our results indicate that it is possible to numerically integrate the coupled CFD–DAEM system without significantly increasing computational overhead. It is also clear, however, that reactor operating conditions, reaction kinetics, and multiphase flow dynamics all have major impacts on the pyrolysis products exiting the reactor. We find that, with the same pre-exponential factors and mean activation energies, inclusion of distributed activation energies in the kinetics can shift the predicted average value of the exit vapor-phase tar flux and its statistical distribution, compared to single-valued activation-energy kinetics. Perhaps the most interesting observed trend is that increasing the diversity of the DAEM activation energies appears to increase the mean tar yield, all else being equal. As a result, these findings imply that accurate resolution of the reaction activation energy distributions will be important for optimizing biomass pyrolysis processes.

Authors:
 [1];  [2];  [1];  [1];  [3]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Univ. of Nebraska-Lincoln, Lincoln, NE (United States)
  3. Iowa State Univ., Ames, IA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1238742
Alternate Identifier(s):
OSTI ID: 1246545
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Analytical and Applied Pyrolysis
Additional Journal Information:
Journal Volume: 117; Journal Issue: C; Journal ID: ISSN 0165-2370
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
97 MATHEMATICS AND COMPUTING; 09 BIOMASS FUELS

Citation Formats

Xiong, Qingang, Zhang, Jingchao, Wiggins, Gavin, Daw, C. Stuart, and Xu, Fei. Coupling DAEM and CFD for simulating biomass fast pyrolysis in fluidized beds. United States: N. p., 2015. Web. doi:10.1016/j.jaap.2015.11.015.
Xiong, Qingang, Zhang, Jingchao, Wiggins, Gavin, Daw, C. Stuart, & Xu, Fei. Coupling DAEM and CFD for simulating biomass fast pyrolysis in fluidized beds. United States. https://doi.org/10.1016/j.jaap.2015.11.015
Xiong, Qingang, Zhang, Jingchao, Wiggins, Gavin, Daw, C. Stuart, and Xu, Fei. 2015. "Coupling DAEM and CFD for simulating biomass fast pyrolysis in fluidized beds". United States. https://doi.org/10.1016/j.jaap.2015.11.015. https://www.osti.gov/servlets/purl/1238742.
@article{osti_1238742,
title = {Coupling DAEM and CFD for simulating biomass fast pyrolysis in fluidized beds},
author = {Xiong, Qingang and Zhang, Jingchao and Wiggins, Gavin and Daw, C. Stuart and Xu, Fei},
abstractNote = {We report results from computational simulations of an experimental, lab-scale bubbling bed biomass pyrolysis reactor that include a distributed activation energy model (DAEM) for the kinetics. In this study, we utilized multiphase computational fluid dynamics (CFD) to account for the turbulent hydrodynamics, and this was combined with the DAEM kinetics in a multi-component, multi-step reaction network. Our results indicate that it is possible to numerically integrate the coupled CFD–DAEM system without significantly increasing computational overhead. It is also clear, however, that reactor operating conditions, reaction kinetics, and multiphase flow dynamics all have major impacts on the pyrolysis products exiting the reactor. We find that, with the same pre-exponential factors and mean activation energies, inclusion of distributed activation energies in the kinetics can shift the predicted average value of the exit vapor-phase tar flux and its statistical distribution, compared to single-valued activation-energy kinetics. Perhaps the most interesting observed trend is that increasing the diversity of the DAEM activation energies appears to increase the mean tar yield, all else being equal. As a result, these findings imply that accurate resolution of the reaction activation energy distributions will be important for optimizing biomass pyrolysis processes.},
doi = {10.1016/j.jaap.2015.11.015},
url = {https://www.osti.gov/biblio/1238742}, journal = {Journal of Analytical and Applied Pyrolysis},
issn = {0165-2370},
number = C,
volume = 117,
place = {United States},
year = {Thu Dec 03 00:00:00 EST 2015},
month = {Thu Dec 03 00:00:00 EST 2015}
}

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Cited by: 63 works
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Works referencing / citing this record:

Quick estimation of f(E) in the distributed activation energy model (DAEM): an inverse problem approach
journal, July 2019


Performance analysis of a heat transfer and sub-grid chemical reaction distributed activation energy model for fire simulations
journal, November 2018