Coal-fueled separated gasification chemical looping combustion under auto-thermal condition in a two-stage reactor system

摘要

A separated gasification chemical looping combustion (SG-CLC) system has been operated auto-thermally, which has high combustion performances and is beneficial for the lifetime of oxygen carrier (OC). In this work, the performances of SG-CLC were compared with in-situ gasification CLC (iG-CLC) in a two-stage reactor system. The iG-CLC has more favorable solid conversion than that of SG-CLC, namely the conversion of iG-CLC reached 97.81% after 10 min while that of SG-CLC was 88.31% at 1050 degrees C. When the oxygen ratio R-O of gasification agent was 3.7%, the auto-thermal operation of SG-CLC could be realized. Under the auto-thermal condition, when the gasification temperature increased from 850 degrees C to 1050 degrees C, the carbon conversion increased from 61.02% to 96.64% while the gaseous combustion efficiency fluctuated near 98.66%. When the reduction temperature varied in that range, the carbon conversion was approximately 87.12% and the combustion efficiencies eta(C) increased from 97.91% to 99.96%. Finally, multi-cycle redox experiments were conducted using both iG-CLC and SG-CLC to probe into the reactivity stability of the OC. Results demonstrated that SG-CLC had satisfying performances in fuel conversion and the stability of reactivity, proving the benefit to lengthen the lifetime of oxygen carrier.