循环流化床下料立管内气固两相流动状态与压力脉动的关系  

Relationships between Pressure Fluctuation and Flow Patterns in Standpipes of Circulating Fluidized Bed

作　　者：张毅[1] 彭园园[1] 魏耀东[1] 时铭显[1] 

机构地区：[1]中国石油大学(北京)化学科学与工程学院,北京102249

出　　处：《过程工程学报》2008年第1期23-27,共5页The Chinese Journal of Process Engineering

基　　金：国家自然科学基金资助项目(编号:20576074);国家重点基础研究发展规划(973)基金资助项目(编号:G2005CB22120103)

摘　　要：在15m高的大型气固循环流化床上对内径90和42mm的下料立管内气固两相流的动态压力进行了测量.实验结果表明,负压差下料立管内的气固两相流动存在着低频压力脉动,压力脉动的强度可以用动态压力的标准方差(Standard deviation,Sd)来表征,且与立管下料的流动状态密切相关.立管下料的流动状态依据颗粒质量流量通量的大小有浓相输送状态和稀密两相共存两种状态.浓相输送状态的压力脉动强度较大,是下行颗粒压缩其夹带气体引起气固两相强烈相互作用导致的;稀密两相共存状态的压力脉动强度较小,是密相段排料的不稳定性和稀相段较弱的气固相互作用共同引起的.立管下料的压力脉动强度随颗粒质量流量通量的增加而增大,对于浓相输送状态,在实验操作范围内[Gs'=550～850kg/(m2·s)],压力脉动的强度与立管下料质量流量通量近似成Sd=0.00875Gs'-4.77的线性关系.Pressure fluctuation in the φ90 mm and φ42 mm standpipes in a 15 m circulating fluidized bed was measured. The gas-solid two-phase flows under negative pressure gradient in the standpipes have low frequency pressure fluctuation, which can be described by standard deviation （Sd）. Flow patterns in standpipes are classified as two types according to solids flux, dense conveying pattern and dilute-dense coexisting flow pattern. The pressure fluctuation intensity is great under the dense conveying pattern, which is mainly caused by intensive mutual action between solid and the gas entrained down. The pressure fluctuation intensity is relative weak under the dilute-dense coexisting flow pattern, which is caused by instabilities of solid discharge at the bottom dense part and weak gas-solid mutual action in the upper dilute part. With the solid flux increasing in the standpipes, pressure fluctuation is more intensive. For the dense conveying pattern, there exists nearly linear relationship between solid flux and pressure fluctuation intensity as Sd=0.008 75 Gs＇-4.77 under the experimental condition of Gs＇=550-850 kg/（m^2·s）.

关 键 词：立管 负压差 流动状态 压力脉动 

分 类 号：TQ021[化学工程]