内循环流化床管式气体分布器的实验研究

摘要

采用内循环流化床,以清水-空气-聚乙烯填料三相体系为研究对象,在常温常压下考察分析管式气体分布器的孔径、开孔率、布气位置等因素对内循环流化床的流体力学特性和传质性能的影响.研究结果表明:低进气量时,孔径小的分布器产生的气泡小且均匀,传质和流化效果较好；高进气量时分布器孔径对内循环流化床的影响较小.随着分布器开孔率增大,曝气阻力的影响减弱,故内循环流化床气含率、循环液速和氧传质系数呈现逐渐增大的趋势.布气位置升高,使气泡停留时间缩短且射流影响加剧,致使内循环流化床传质性能和流体力学性能不佳.文中实验为内循环流化床气体分布器的结构优化以及选择合适的布气位置提供依据和理论分析,对工业应用有着重要的意义.%With three-phase system of water-air-polyethylene packing as research object,the effect of aperture,opening rate and installation site of the straight pipe gas distributor on the hydrodynamic characteristics and mass transfer performance of the internal circulation fluidized bed was investigated and analyzed at the normal temperature and pressure.It indicates that when the air inflow is low,the distributor with small aperture generates the small and well-distributed bubbles,resulting in a favorable effect of mass transfer and fluidization ; when the air inflow is high,the aperture of distributor has a little effect on the internal circulation fluidized bed.The influence of aeration resistance weakens with the increasing of opening rate,thus gas holdup,circulating fluid velocity and oxygen transfer coefficient of the internal circulation fluidized bed presents a trend of increase.Rising installation site can shorten the bubble residence time and exacerbate jet flow,which leads to poor mass transfer performance and bad hydrodynamic characteristic of the internal circulation fluidized bed.This experiment provides the basis and theoretical analysis for the structure optimization of gas distributor and the best choice of installation site,so it is of great significance to industrial application in the future.