煤炭地下气化燃空区发育及能量回收评价

Evaluation of gasification cavity growth and gas energyrecovery in underground coal gasification

  • 摘要: 气化燃空区的发育状况监测以及能量回收的评价对于实现高效的煤炭地下气化(UCG)以及气化过程的精确监测与控制十分重要。在人工煤层构建2种不同类型的气化通道模型(链接孔模型/同轴孔模型),依次进行3次大型UCG模拟实验,通过分层位温度监测法观察气化过程中燃烧带和燃空区的发育衍化,研究了不同的气化剂组成(O2,CO2,H2O等)、配比、流速等实验操作参数作用下对生成气化产物中煤气成分及热值的影响,同时建立了基于化学计量理论的能量回收评价方法,并评估整个地下气化过程的气化效率、煤炭消耗量与煤产气量等。研究结果表明:分层位温度监测能反映气化过程中燃烧带以及燃空区的发育情况;气化区域的衍化范围以及衍化速率与气化通道的类型密切相关,2次链接孔模型实验所得的衍化范围与速率的结果均为同轴孔模型实验的2倍以上;地下气化过程中的高温环境更有利于气化过程的持续进行,在高温条件下生成煤气中可燃气体的组分比例增高;煤炭的消耗量以及能量回收率与采用的气化通道类型也密切相关,链接孔模型实验生成的气化燃气相对同轴孔模型热值较高,并且链接孔模型实验的能量回收率也高于同轴孔模型实验。

     

    Abstract: In order to realize the accurate detection and control of underground coal gasification (UCG) process,the monitoring on the development of gasification cavity and the evaluation on the energy recovery are important to realize an efficient UCG.In this paper,two different gasification channel models were constructed by artificial coal seam for the UCG simulation experiment.Through layering stratified temperature detection method,this study investigated the development of gasification cavity and combustion cavity,the effect of different gasification agent composition(O2,CO2,H2O,etc.),ratio,flow rate and other experimental operating parameters on gas composition and calorific value.At the same time,an evaluation method of energy recovery based on stoichiometry theory was established,and the gasification efficiency,coal consumption and coal gas production of the whole underground gasification process were evaluated.The results show that the layering stratified temperature detection method can reflect the development of combustion zone and combustion cavity.The evolution range and rate of gasification region are related to the type of gasification channel,the range and rate of evolution in two experiments with the link hole model are more than 2 times of that with the shaft hole model.The high temperature environment of UCG is conducive to the continuous gasification process,under the condition of high temperature,the proportion of combustible gas in the generated gas increases.The coal consumption and energy recovery are closely related to the gasification channel model.Comparing two models,with the link hole model,the calorific values of gas is higher and the energy recovery is also higher than that with the shaft hole model.

     

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