287914 Reducer Performance of Chemical Looping Reactors: Mixing and Reaction Effects

Monday, October 29, 2012: 2:45 PM
410 (Convention Center )
L. - S. Fan, Liang Zeng, Andrew Tong and Qiang Zhou, William G. Lowrie Department of Chemical and Biomolecular Engineering, The Ohio State University, Columbus, OH

With the pressing need for clean, efficient, and cost-effective energy sources, the chemical looping strategy has evolved as a promising alternative to the traditional carbonaceous fuel conversion process. The syngas chemical looping (SCL) process co-generates electricity and hydrogen with in-situ CO2 capture from coal derived syngas through the cyclic reduction and oxidation of an iron oxide based oxygen carrier. The SCL process features countercurrent gas-solid moving-bed reactor that converts syngas to CO2 while reducing the oxygen carriers. The countercurrent reducer in the SCL process at the Ohio State University has been operated for a combined time of more than 300 hours in a 2.5 kWth bench scale moving-bed reactor and a 25 kWth subpilot scale integrated system. A syngas conversion in excess of 99.5% and an oxygen carrier conversion of nearly 50% have been obtained. The thermodynamic analysis indicates that the countercurrent moving-bed reducer offers better gas and solids conversion behavior, compared to the fluidized-bed reducer. In this study, effects of the mixing and the reaction in the reducer of a chemical looping reactor system operated in the two distinct flow patterns represented by these two types of reactors, i.e., countercurrent moving-bed and the fluidized-bed, are described in terms of experimental results and reactor modeling. Further, the importance of the thermodynamic properties of the oxygen carrier in the reducer performance is highlighted in this study.

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