加压二维鼓泡床气固流动特性的数值模拟  

Numerical Simulation on Gas-solid Flow Characteristics of a 2D Pressurized Bubbling Fluidized Bed

作　　者：高智雪 郝振华[1] 宋素芳[3] 聂伟[1] 房倚天[1] 

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,太原030001 [2]中国科学院大学,北京100049 [3]太原科技大学化学与生物工程学院,太原博士讲师030021

出　　处：《煤炭转化》2018年第2期44-50,66,共8页Coal Conversion

基　　金：国家自然科学基金资助项目(21606250)和中国科学院青年创新促进会基金项目(2016162).

摘　　要：采用欧拉双流体模型模拟了加压下二维鼓泡床内的气固流动特性,结果表明:在相同的表观气速下,加压使气泡体积分数增大,气泡相与乳化相间的分解越发明显,气固两相流动、混合剧烈;同时,床层中上部颗粒轴向速度的径向分布不均匀性增强:中心区颗粒速度增加,近壁区下降;随着操作压力变大,流化床膨胀高度增大,相应地,整体气含率增大,床层下部的颗粒浓度减小,而上部颗粒浓度增加,固含率在轴向上的分布更均匀;床层压力波动主要由两种成分构成:低频率高幅值和低幅值高频率成分.压力脉动强度随床高的增加呈现先增大后迅速减小的趋势;此外,加压下床层压力脉动强度变大,即床压波动更加剧烈;而且加压下颗粒拟温度增大,即颗粒速度脉动增强.The gas-solid flow characteristics in a two-dimension pressurized bubbling fluidized bed were investigated through a simulation based on Euler two-fluid model.The results show that under the same apparent gas velocity,the elevated operating pressure can cause a higher volume fraction of bubbles and a more obvious boundary between bubbles and emulsions,which result in much stronger flow and mixing between two phases.Meanwhile,the radial distribution of solids' vertical velocity in the middle and upper of bed presents more inhomogeneous:solids vertical velocity increases in the central region,while decreases near the wall.Moreover,the bed expansion height increases with the elevated operating pressure;accordingly,gas holdup increases.The distribution of solid holdup becomes more homogeneous in the radical direction:the particles concentration decreases in the bottom and increases in the top.The fluctuation of bed pressure is primarily composed of two components:one with low-frequency/high-amplitude,the other with low-amplitude/high-frequency.The intensity of pressure pulsation inside the bed shows a tendency to increase initially then decrease rapidly with increase of the bed height.In addition,the intensity of pressure pulsation increases with the elevated operating pressure,indicating that the bed pressure fluctuates more intensely.Furthermore,particles show higher granular temperature with the elevated operating pressure,indicating of an enhanced particle velocity fluctuation.

关 键 词：加压 鼓泡床 气固两相流 数值模拟 双流体模型 

分 类 号：O359[理学—流体力学] TQ545[理学—力学]