高密度下行床内颗粒浓度径向分布的研究  

An Experimental Study of the Radial Solids Profiles in a High-density Downer

作　　者：陈恒志[1] 李洪钟[1] 柳华[1] 李连轩 

机构地区：[1]中科院过程工程研究所多相反应开放实验室,北京100080

出　　处：《化学反应工程与工艺》2004年第1期41-46,共6页Chemical Reaction Engineering and Technology

摘　　要：　在自行设计的一套下行循环流化床内进行了低气速、高浓度下行床内颗粒浓度的分布研究。实验分别采用了硅胶和FCC颗粒,在床层截面平均浓度最高到12%范围内进行了下行床不同截面上颗粒浓度径向分布的研究,并进一步分析了床层颗粒浓度对稀相中心区、环形浓相区浓度径向分布的影响。研究表明,在同一截面,随着床层颗粒平均浓度的增加,浓度分布趋于均匀;在截面平均浓度相近,浓度的径向分布沿轴向从上到下逐渐趋于均匀。颗粒的相对浓度的最大值随截面平均浓度的增加而减小,其在径向的位置基本不变。实验还发现,床层截面平均浓度的增加,浓相区内颗粒浓度的分布更均匀,而对稀相区内颗粒浓度分布没有明显的影响。Experiments were carried out in a 5.6m tall, 0.08m ID high-density gas-solids downflow fluidized bed. Silica gel (ρ_p=750 kg/m^3, d_p=128 μ m) and FCC particles (ρ_p=992 kg/m^3, d_p=82 μ m) were used. The solids holdup as high as 12% has been achieved. The results showed that the radial distribution of local solids fraction is uniform in the central region and a relative high concentration ring exists near the wall, which becomes more uniform as the cross-sectional average solids concentration increased. It was found experimentally that the peak value of the relative solids concentration decreases with increasing average solids concentration, but its radial position does not change. In the dense region, the radial distribution is more uniform when increasing the average solids concentration. In the dilute region, the radial distribution has no variety when the average solids concentration is changed. The influence of the different kinds of particles on the radial distribution with increasing the cross-sectional average solids concentration is different.

关 键 词：颗粒浓度 下行床 传热效率 转化率 产率 循环流化床 

分 类 号：TQ051.13[化学工程]