煤矿乏风瓦斯热逆流氧化反应器的数学模型和试验

Mathematical model and experiment of thermal reversal oxidation of VAM in coal mine

建立了低浓度甲烷热氧化逆流反应器的数学模型,运用计算流体力学方法进行数值计算,得到各种操作参数下的温度分布及甲烷浓度分布曲线,并将数值计算结果与实验结果进行了对比,并对影响氧化床运行特性的几个主要因素进行了分析。结果表明,氧化床内温度分布基本成M型,高温区以及甲烷浓度分布曲线沿气体流动方向周期性往复移动;进口甲烷混合气的浓度越大,温度分布峰值就越高并而且更靠近进口端,高温区域的宽度也增宽,而且高温区域中间凹度加深,进出口温度梯度也会增大;预混甲烷气体的流速从0.15 m/s增大到0.70 m/s时,最高温度峰值和高温区变化不大,因为流速增大一方面使单位时间进入氧化床内反应物的数量增加,放出了更多的热量,但是另一方面气体流速升高而带走的对流换热量也会大量增加。

A mathematical model of thermal reversal oxidation of the low concentration methane was established in this paper. The computational fluid dynamics method was used to simulate the temperature distribution and methane con- centration distribution under various operating parameters. The calculated values of methane conversion showed good a- greement with the corresponding available experimental data. The model was used to investigate the effects of opera- tional conditions such as the approach velocity and equivalence ratio on the oxidation of methane. The results show that the temperature distribution within the bed is substantially M-typed;the high temperature zone and the methane con- centration distribution curve along the direction of gas flow move periodically;the greater the inlet methane concentra- tion, the higher the temperature peak, the closer to the inlet end of the temperature curve and the wider the high-tem- perature region;if the premixed methane gas flow rate increases from O. 15 m/s to 0.70 m/s, the maximum tempera- ture peak and the high temperature zone change little, because as the gas flow velocity increases, both the heat relea- sing in the reaction bed and the heat carried out by the flow increase.