煤矿乏风瓦斯氧化床取热空间特性对床层取热影响

摘要

Based on the efficiency of the mathematical model verified with the experiment and the heat absorption from the mine ventilation air oxidized bed,a numerical study method was applied to study the heat absorption space features(honeycomb ceramic filling rate and honeycomb ceramic hole opening rate) of the mine ventilation air methane oxidized bed affected to the heat absorption.The calculation results showed that when the honeycomb ceramic filling rate of the heat absorption space increased,on one hand,the bed physical velocity of the oxidized bed would be increased,the gas flow rate around the external wall of the heat exchanger would be increased and the convection heat transfer of the heat exchanger would be enhanced.On the other hand,the gas flow of the heat exchanger directly to the convection heat exchanger was reduced,the heat absorption of the heat exchanger was weakened,the honeycomb ceramic filling rate of the heat absorption space would increase the contradiction dual characters of the heat absorption,which would make the heat absorption rate of the heat exchanger firstly increased and then decreased.When the filling ratc was 0.49,there would be the maximum existed in the heat absorption rate of the internal heat exchanger within the oxidized bed.The hole opening rate of the filling honeycomb ceramics in the heat absorption space reduced would cause a mismatch of the resistance between the heat exchanger area and the honeycomb ceramic filling area within the heat absorption space,the gas would be priority to select the area of the heat exchanger with a small resistance and would enhance the heat absorption of the heat exchanger.But the resistance difference of the heat exchanger too high would affect the distribution uniformity of the downstream bed gas in the heat absorption are and the hole opening rate of the filling honeycomb ceramic in the heat absorption space would be 0.64 as selected.%在试验验证数学模型有效性的基础上,基于煤矿乏风氧化床的取热,采用数值研究的方法,研究了煤矿乏风瓦斯氧化床取热空间特性(蜂窝陶瓷填充率与蜂窝陶瓷开孔率)对取热的影响,计算结果表明:取热空间蜂窝陶瓷填充率增大时,一方面引起氧化床层物理流速的增大,换热器外壁周围的气体流速随之增大,强化换热器的对流换热;另一方面使与换热器进行直接对流换热的气体量减少,削弱换热器的取热;取热空间蜂窝陶瓷填充率增大对取热影响的矛盾两面性使换热器取热率呈现先增大后减小趋势,在填充率为0.49时,氧化床内置换热器取热率存在极大值;取热空间填充蜂窝陶瓷开孔率的减小使取热空间内换热器所在区域与蜂窝陶瓷填充区域阻力不匹配,气体会优先选择阻力小的换热器所在区域,强化换热器的取热,但是取热区阻力相差太大,又影响取热区下游床层气体分布的均匀性,取热空间填充蜂窝陶瓷开孔率常选取为0.64.