回料流入口高度对循环流化床提升管流动特性的影响  

Effect of return gas-solids stream position on flow properties of circulating fluidized bed

作　　者：孙绍增[1] 王正阳[1,2] 杜明坤[1] 邓启刚[1] 吴少华[1] 

机构地区：[1]哈尔滨工业大学能源科学与工程学院,黑龙江哈尔滨150001 [2]哈尔滨工业大学土木工程学科博士后流动站,黑龙江哈尔滨150001

出　　处：《化工学报》2010年第1期60-65,共6页CIESC Journal

基　　金：国家科技支撑计划子课题项目(2006BAA03B01-07)~~

摘　　要：The axial pressure drop profile and the radial solids distribution were measured in a circulating fluidized bed for evaluating the effects of return gas-solids stream position on the riser flow properties.The saturation carrying capacity of gas for Geldart B typed particles and the flow mode of return gas-solids stream in the bed were discussed.It was found that arranging the inlet at a higher position of the riser would make the bottom bed leaner when U0 was high and Gs was low.When Gs increased,the longer influenced region of return particles and a small air-staging through lifting the loosening air injection position made the bottom bed become denser significantly.The deceleration and residence of return particles caused a relatively denser but asymmetrical region in the vicinity of inlet.But much more symmetrical solids distribution profile was found in the upper and lower regions far away from the inlet.The effects of inlet height on the flow properties of the riser with air-staging also were analyzed.The secondary air injection below the solids inlet could not cut off the solids exchange in the bed.The bed solids concentration increased when the particles inlet moved to a higher position of the bed when air-staging was adopted.Using CO2 as tracer,the dispersion of the loop-seal-fluidizing air for transmitting the return particles was investigated.It was found that the loop-seal fluidizing air dispersion rate was low but can be enhanced by the secondary air injection.The axial pressure drop profile and the radial solids distribution were measured in a circulating fluidized bed for evaluating the effects of return gas-solids stream position on the riser flow properties. The saturation carrying capacity of gas for Geldart B typed particles and the flow mode of return gas-solids stream in the bed were discussed. It was found that arranging the inlet at a higher position of the riser would make the bottom bed leaner when U0 was high and Gs was low. When Gs increased, the longer influenced region of return particles and a small air-staging through lifting the loosening air injection position made the bottom bed become denser significantly. The deceleration and residence of return particles caused a relatively denser but asymmetrical region in the vicinity of inlet. But much more symmetrical solids distribution profile was found in the upper and lower regions far away from the inlet. The effects of inlet height on the flow properties of the riser with air-staging also were analyzed. The secondary air injection below the solids inlet could not cut off the solids exchange in the bed. The bed solids concentration increased when the particles inlet moved to a higher position of the bed when air-staging was adopted. Using CO2 as tracer, the dispersion of the loop-seal fluidizing air for transmitting the return particles was investigated. It was found that the loop-seal fluidizing air dispersion rate was low but can be enhanced by the secondary air injection.

关 键 词：循环流化床 回料气固两相流 入口高度 颗粒浓度分布 回料风的扩散 

分 类 号：TQ051.1[化学工程]