吸附床内气体浓度分布的测定

MEASUREMENT OF GAS CONCENTRATION DISTRIBUTION IN ADSORPTION BED

1引言固定床内流体的轴向与径向混合作用对床层内的传质、传热和反应过程有很大的影响，研究固定床内流体的混合特性一直受到各国学者的重视。固定床中流体与固体颗粒间的传质与流体的混合作用是相互影响的。一些学者对吸附床中气体澎合特性进行了研究。l－3。，但他们所使用的固定床实验装置内径比较小（100mm以下），一般都采用改变床层高度，在床层出口端收集气体样品进行分析，测定不同床层截面上气体浓度分布。这一检测气体浓度的方法对气、固间有较大传质速率的吸附床会产生较大的误差。为准确测定床层内气体浓度及变化，建立了气体浓度微机检测系统和内径为267nlm的气相吸附装置，催化燃烧式气体浓度传感器置于床层内，可连续检测和记录床层内历点浓度。应用该装置测定了甲烷－空气－SA分子筛物系在床层内不同横截面上甲烷浓度分布及随时间变化的数据。

A gas concentration detecting device consisting of catalytic burning sensors for gas concentration detection and an accompanying on-line microcomputer data collecting system was set-up to investigate axial and radial mixing characteristics of gas in adsorption bed. It could measure and record combustible gas concentration at sixteen different positions simultaneously in adsorption bed. Experiments were carried out with methane-air-5A molecular sieve in a267 mm diameter adsorption column at different gas flow rates. Methane used as adsorbate was continuously fed into the center of bed entrance section and its concentration distributions were obtained at three different levels of the column. This device can also be used to measure temperature distribution if temperature sensors are used instead of that for gas concentration measurement.