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超低浓度煤层气由于甲烷含量低、浓度变化大而较难加以利用。采用实验和数值模拟的方法,研究了超低浓度煤层气在流化床中的燃烧,分析了床层温度、甲烷体积浓度、流化风速对甲烷燃烧效率的影响,并用数学模型预测了甲烷沿床层高度方向的分布。研究表明,数学模型和实验数据吻合较好。床层温度是煤层气燃烧反应的关键因素,甲烷的转化率随着床层温度的升高而增加。燃烧反应主要发生在乳化相,且主要集中在床层的下部。甲烷的转化率随着流化风速和煤层气中甲烷浓度的增加而减少。在床层温度为650℃时,甲烷浓度低于1%的煤层气的甲烷转化率均大于93%。增加床层高度可使甲烷完全转化。
Ultra-low concentrations of CBM are difficult to exploit because of low methane content and large concentration variations. The effects of bed temperature, methane concentration and fluidization velocity on the combustion efficiency of methane were studied by means of experiments and numerical simulations. The mathematical model was used to predict the methane Distribution of bed height direction. The research shows that the mathematical model is in good agreement with the experimental data. The bed temperature is the key factor for the CBM combustion reaction, and the methane conversion rate increases with the bed temperature. The combustion reaction occurs mainly in the emulsified phase and mainly in the lower part of the bed. Methane conversion decreases with increasing fluidization velocity and methane concentration in coalbed methane. Methane conversion of coalbed methane with methane concentration less than 1% was more than 93% when the bed temperature was 650 ℃. Increasing the bed height can completely convert methane.