High-efficiency and pollution-controlling in-situ gasification chemical looping combustion system by using CO2 instead of steam as gasification agent |
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Authors: | Zhe Shen Zhiyu Huang |
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Affiliation: | 1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploration, Southwest Petroleum University, Chengdu 610500, China;2.School of Energy and Architecture, Xi'an Aeronautical University, Xi'an 710077, China |
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Abstract: | Using CO2 as gasification agent instead of steam in in-situ coal gasification chemical looping combustion (iG-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 CO2 as gasification agent is concentrated on. The effects of steam to carbon ratio (S/C) and CO2 to carbon ratio (CO2/C) on the fuel reactor temperature, char conversion, syngas composition and CO2 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 CO2-based case with CO2/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 to 1.4 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 CO2-based case within the same φ range. In terms of iG-CLC power plant, recycling partial CO2 to the fuel reactor improves the overall performance. Approximately 3.9% of net power efficiency are increased in CO2-based plant, from steam-based plant. Higher CO2 capture efficiency and lower CO2 emission rate are observed in CO2-gasified iG-CLC power plant, expecting to be 90.63% and 85.18 kg·MW-1·h-1, respectively. |
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Keywords: | 2 Steam iG-CLC Comparative study |
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