Using CO_2 as gasification agent instead of steam in in-situ coal gasification chemical looping combustion(i G-CLC)power plant can eliminate energy consumption for steam generation, thus obtaining higher system effici...Using CO_2 as gasification agent instead of steam in in-situ coal gasification chemical looping combustion(i G-CLC)power plant can eliminate energy consumption for steam generation, thus obtaining higher system efficiency. In this work, a comparative study of iG-CLC power plant using steam and CO_2 as gasification agent is concentrated on. The effects of steam to carbon ratio(S/C) and CO_2 to carbon ratio(CO_2/C) on the fuel reactor temperature,char conversion, syngas composition and CO_2 capture efficiency are separately investigated. An equilibrium carbon conversion of 88.9% is achieved in steam-based case as S/C ratio increases from 0.7 to 1.1, whereas a maximum conversion of 84.2% is obtained in CO_2-based case with CO_2/C ranging from 0.7 to 1.1. Furthermore the effects of oxygen carrier to fuel ratio(φ) on system performances are investigated. Increasing φ from 1.0 to1.4 helps to achieve char conversion from 75.9% to 88.9% in steam-based case, by contrast the char conversion can achieve 66.3%–84.2% in CO_2-based case within the same φ range. In terms of iG-CLC power plant, recycling partial CO_2 to the fuel reactor improves the overall performance. Approximately 3.9% of net power efficiency are increased in CO_2-based plant, from steam-based plant. Higher CO_2 capture efficiency and lower CO_2 emission rate are observed in CO_2-gasified iG-CLC power plant, expecting to be 90.63% and 85.18 kg·MW-1·h-1,respectively.展开更多
文摘Using CO_2 as gasification agent instead of steam in in-situ coal gasification chemical looping combustion(i G-CLC)power plant can eliminate energy consumption for steam generation, thus obtaining higher system efficiency. In this work, a comparative study of iG-CLC power plant using steam and CO_2 as gasification agent is concentrated on. The effects of steam to carbon ratio(S/C) and CO_2 to carbon ratio(CO_2/C) on the fuel reactor temperature,char conversion, syngas composition and CO_2 capture efficiency are separately investigated. An equilibrium carbon conversion of 88.9% is achieved in steam-based case as S/C ratio increases from 0.7 to 1.1, whereas a maximum conversion of 84.2% is obtained in CO_2-based case with CO_2/C ranging from 0.7 to 1.1. Furthermore the effects of oxygen carrier to fuel ratio(φ) on system performances are investigated. Increasing φ from 1.0 to1.4 helps to achieve char conversion from 75.9% to 88.9% in steam-based case, by contrast the char conversion can achieve 66.3%–84.2% in CO_2-based case within the same φ range. In terms of iG-CLC power plant, recycling partial CO_2 to the fuel reactor improves the overall performance. Approximately 3.9% of net power efficiency are increased in CO_2-based plant, from steam-based plant. Higher CO_2 capture efficiency and lower CO_2 emission rate are observed in CO_2-gasified iG-CLC power plant, expecting to be 90.63% and 85.18 kg·MW-1·h-1,respectively.
