低气液流速下三相固定床的传质特性  

Mass transfer characteristics in three-phase fixed bed reactors under low gas and liquid flow rates

作　　者：杨军[1] 黄子宾[1] 程振民[1] 

机构地区：[1]华东理工大学化学工程联合国家重点实验室,上海200237

出　　处：《化学工程》2016年第11期13-18,共6页Chemical Engineering(China)

基　　金：中国石油天然气集团公司重大科技专项基金(2010E-2004-02)

摘　　要：在低气液流速下对三相固定床气液并流向上和并流向下操作过程的传质特性进行了对比研究。分别采用物理吸收法和化学吸收法测定液相体积传质系数k_L^a与气液相际比表面积a,利用电容层析成像系统测定了床层持液量,并分别使用直径为1.9,4.0,9.3 mm的球形填料进行实验,考察颗粒的尺寸效应。结果表明:k_L^a和a均随气液流速增大而增大,其中向上流动受气液流速影响均很明显,而向下流动受液速影响较大。颗粒尺寸越小,k_L^a与a越大。相同气液流速下,向上流动相比于向下流动,k_L^a高出45%,a高出75%。采用量纲分析法拟合实验数据,得到k_L^a与气液相Reynolds数、液相Weber数之间的关联式。根据稳定气泡理论模型,得到气液并流向上过程a的预测关联式。The comparisons of mass transfer characteristics in three-phase fixed bed reactors with gas-liquid concurrent upflow and downflow were studied under low gas and liquid flow rates. The liquid volumetric mass transfer coefficient k_La was measured by the physical absorption method,while the interfacial area a was measured by chemical absorption system. The electrical capacitance tomography system was used to measure the liquid holdup. In order to investigate the particle size effect,three kinds of spherical particles（ 1. 9,4. 0,9. 3 mm） were used. The results show that both k_La and a increases with an increase of either gas or liquid flow rate as well as a decrease of particle size. In particular,the mass transfer characteristics are significantly affected by both gas and liquid flow rates in upflow process,while they are obviously influenced by the liquid flow rate in downflow process.Respectively,at constant phase flow rate,the k_La is 45% higher and a is 75% higher in upflow operation than that in downflow operation. The empirical correlations of k_La, obtained through dimensional analysis, fit the experimental data well. According to the stable bubble theoretical model,an empirical correlation for predicting a in gas-liquid concurrent upflow process is also developed.

关 键 词：三相固定床 气液并流向上 气液并流向下 传质系数 相际比表面积 

分 类 号：TQ051.14[化学工程]