438 / 2018-12-27 09:45:52

Chemical looping gasification of Zhundong lignite in the fluidized bed with a natural Mn-Fe based oxygen carrier

chemical looping; coal; gasification

全体主题 > 燃料利用与化学循环技术

化学链气化作为新型气化方式，采用循环载氧体为气化过程供氧，无需空分制氧，气化成本低。本文以准东煤为燃料，锰矿石为载氧体，基于鼓泡流化床开展煤化学链气化实验研究，考察温度、比氧耗（燃料完全燃烧耗氧与载氧体理论供氧摩尔比，φ）和循环次数对准东煤化学链气化特性的影响规律。结果表明：煤化学链气化反应产生的合成气主要由CO、CO2、CH4和H2组成；随着φ的升高，CO2浓度逐渐下降、H2浓度逐渐上升，CO和CH4浓度基本不变；有效气组分（CO+CH4+H2）随φ的增加而增加，当φ=4、温度为900℃时，有效气组分达到79%；温度升高加快气化反应速率，碳转化率随φ增大而增大。50次循环实验发现：随循环次数的增加，载氧体反应活性随着循环次数增加略有提升并逐渐稳定。EDS分析结果显示煤中Na在载氧体表面沉积，含量随循环次数增加略有上升。
Chemical Looping Gasification (CLG) is one new technology which uses circulating oxygen carrier for gasification process. It is a low cost gasification technology without air separation process. The present work investigates the gasification behavior of the Zhundong lignite using a Mn ore as oxygen carrier in a bubbling fluidized bed. Effects of temperature, fuel to oxygen carrier ratio (φ) and reduction-oxidation cycles are evaluated. Results indicated the main gases in syngas are CO, CO2, CH4 and H2. With the increase of φ, the CO2 concentration decreases and H2 concentration increases. Meanwhile, the concentrations of CO or CH4 are almost stable. In total, the concentration of effective gases (CO+CH4+H2) increases with the increase of φ. At the condition of φ=4 and a reaction temperature of 900℃, the effective gas concentration reaches 79%. A high temperature or a high value of φ leads to a high carbon conversion. 50 cycles’ experiments suggest that the reactivity of oxygen carriers slightly increases with the cycles and gradually tends to be stable. Na deposition on the bed particles and its amount increased with the cycles was found by EDS analysis.