低阶煤固定流化床热解及半焦气化实验研究

采用固定流化床研究了三种低阶煤的常压热解及其热解半焦的气化特性，探究了样品粒度、反应温度、反应时间及流化气中O2含量对上述过程的影响，确定了循环流化床热解-气化耦合工艺适宜的反应条件。结果表明，在实验选择范围内，样品的粒度基本不会影响热解过程，在水蒸气气氛下，温度越高，热解气体产率越高，半焦产率越低；600 ℃和20 min时能获得最高的焦油产率。循环流化床热解-气化耦合工艺碳的有效利用率率高于原煤固定流化床气化工艺，同时副产煤焦油；温度越高，有效气产率和有效碳转化率越高；实验范围内，O2含量对合成气产率的影响较小，但可以调节H2和CO的相对含量；900 ℃、半焦气化15 min即可获得较理想的合成气产率及有效碳转化率。

EXPERIMENTAL STUDY OF LOW-RANK COAL PYROLYSIS AND CHAR GASIFICATION IN FIXED FLUIDIZED BED REACTOR

The pyrolysis characters of three kinds of low-rank coals and gasification performance of their char were studied in a fixed fluidized bed reactor. The effect of sample particle size, reaction temperature, time，and the content of O2 in fluidizing gas on test results were explored. The suitable reaction conditions for circulating fluidized bed pyrolysis coupled with gasification process were determined. The results showed that the sample particle size could hardly affect the pyrolysis process. The gas yield of coal pyrolysis increased and the char yield decreased with the increase of temperature in steam atmosphere. The highest tar yield was achieved at 600 ℃ and 20 min. The effective gas yield of circulating fluidized bed pyrolysis coupled with gasification process which can produce tar simultaneously was higher than that of coal gasification in fixed fluidized bed reactor. The higher the temperature of gasification was, the higher the effective gas yield and carbon conversion yield was. The O2 content had a little influence on syngas yield but could adjust the relative content of CO and H2 in the experimental range. It can be obtained an ideal syngas yield and effective carbon conversion yield at 900 ℃ and 15 min.