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Title: Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling

Abstract

Chemical-looping combustion with oxygen uncoupling (CLOU) is a process using gaseous or solid hydrocarbon fuels and is a promising carbon capture and storage (CCS) technology. In CLOU, combustion of the fuel is achieved through the release of gaseous O2 from an oxygen carrier material such as CuO and is favored at high temperatures and low O2 partial pressures. The primary objectives of this study were to (1) compare values for the apparent rate constant kov(T) for the overall rate of reduction of a CuO carrier, either alone or in the presence of coal char obtained from the pyrolysis of Powder River Basin (PRB) coal, and (2) develop and validate a computational fluid dynamics (CFD) model for the CuO/PRB coal char system based on known kinetics of the individual CuO and Cu2O reduction, combustion, and gasification reactions. Two oxygen carriers consisting of 20 wt % CuO/Al2O3 and 9 wt % CuO/Al2O3 were prepared by physical mixing and by incipient wetness impregnation (IWI), respectively. Kinetic analyses were conducted in the temperature range of 850–1100 °C. The CFD model typically reproduced experimental values of kov(T) to within ±10%. We note the increase in kov(T) caused by addition of only 0.075 g of PRBmore » char per gram of CuO was modest at 1100 °C, but was more than 3-fold at 850 °C. Combustion and gasification of the coal char not only produced CO, opening another pathway for CuO reduction in addition to the CLOU reaction, but also resulted in the over-reduction of Cu2O to the undesired metallic Cu. Production of Cu metal increased with respect to char loading.« less

Authors:
ORCiD logo [1];  [1];  [2];  [3];  [3]
  1. National Energy Technology Laboratory (NETL), Pittsburgh, PA (United States); Leidos Research Support Team, Pittsburgh, PA (United States)
  2. National Energy Technology Laboratory (NETL), Pittsburgh, PA (United States)
  3. National Energy Technology Laboratory (NETL), Morgantown, WV (United States)
Publication Date:
Research Org.:
National Energy Technology Laboratory (NETL), Pittsburgh, PA, Morgantown, WV, and Albany, OR (United States)
Sponsoring Org.:
USDOE Office of Fossil Energy (FE)
OSTI Identifier:
1635624
Grant/Contract Number:  
89243318CFE000003
Resource Type:
Accepted Manuscript
Journal Name:
Energy and Fuels
Additional Journal Information:
Journal Volume: 34; Journal Issue: 1; Journal ID: ISSN 0887-0624
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Burgess, Ward A., Means, Nicholas C., Howard, Bret H., Smith, Mark W., and Shekhawat, Dushyant. Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling. United States: N. p., 2019. Web. https://doi.org/10.1021/acs.energyfuels.9b02183.
Burgess, Ward A., Means, Nicholas C., Howard, Bret H., Smith, Mark W., & Shekhawat, Dushyant. Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling. United States. https://doi.org/10.1021/acs.energyfuels.9b02183
Burgess, Ward A., Means, Nicholas C., Howard, Bret H., Smith, Mark W., and Shekhawat, Dushyant. Tue . "Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling". United States. https://doi.org/10.1021/acs.energyfuels.9b02183. https://www.osti.gov/servlets/purl/1635624.
@article{osti_1635624,
title = {Effect of Char Loading on Reduction Kinetics of Cu-Based Oxygen Carriers in a Drop-Tube Fluidized-Bed Reactor at Temperatures from 850 to 1100 °C: Experiment and CFD Modeling},
author = {Burgess, Ward A. and Means, Nicholas C. and Howard, Bret H. and Smith, Mark W. and Shekhawat, Dushyant},
abstractNote = {Chemical-looping combustion with oxygen uncoupling (CLOU) is a process using gaseous or solid hydrocarbon fuels and is a promising carbon capture and storage (CCS) technology. In CLOU, combustion of the fuel is achieved through the release of gaseous O2 from an oxygen carrier material such as CuO and is favored at high temperatures and low O2 partial pressures. The primary objectives of this study were to (1) compare values for the apparent rate constant kov(T) for the overall rate of reduction of a CuO carrier, either alone or in the presence of coal char obtained from the pyrolysis of Powder River Basin (PRB) coal, and (2) develop and validate a computational fluid dynamics (CFD) model for the CuO/PRB coal char system based on known kinetics of the individual CuO and Cu2O reduction, combustion, and gasification reactions. Two oxygen carriers consisting of 20 wt % CuO/Al2O3 and 9 wt % CuO/Al2O3 were prepared by physical mixing and by incipient wetness impregnation (IWI), respectively. Kinetic analyses were conducted in the temperature range of 850–1100 °C. The CFD model typically reproduced experimental values of kov(T) to within ±10%. We note the increase in kov(T) caused by addition of only 0.075 g of PRB char per gram of CuO was modest at 1100 °C, but was more than 3-fold at 850 °C. Combustion and gasification of the coal char not only produced CO, opening another pathway for CuO reduction in addition to the CLOU reaction, but also resulted in the over-reduction of Cu2O to the undesired metallic Cu. Production of Cu metal increased with respect to char loading.},
doi = {10.1021/acs.energyfuels.9b02183},
journal = {Energy and Fuels},
number = 1,
volume = 34,
place = {United States},
year = {2019},
month = {12}
}

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