气固流化床中双组分混合颗粒的流态化特性

Flow behavior of binary mixture particles in gas-solid fluidized beds

在一套ф500mm×12500mm大型有机玻璃冷模实验装置中,采用FXC-П/32型压力巡检仪测量了双组分混合颗粒体系沿流化床轴向的颗粒浓度分布,采用容积法测量了不同操作条件下自由空域内双组分混合颗粒的饱和夹带量,并根据稀相空间的轴向颗粒浓度获得了双组分混合颗粒的输送分离高度(TDH)。实验结果表明:混合颗粒在密相床的平均空隙率在小颗粒质量分数为0.4时存在一最小值;双组分混合颗粒的TDH随表观气速的增加而增大,随小颗粒质量分数的增加也增大。在自由空域内双组分混合颗粒的饱和夹带量随表观气速的增加而增加,当表观气速小于0.6m·s-1时,随表观气速增加明显;当表观气速大于0.6m·s-1时,增加趋势减缓。而当表观气速小于0.5m·s-1时,双组分混合颗粒的饱和夹带量随小颗粒质量分数增加,变化趋势不明显;当表观气速大于0.5m·s-1时,则随小颗粒质量分数的增加而增大明显。通过对实验结果的分析,建立了双组分混合颗粒TDH的数学模型,模型值与实验值吻合较好。

The axial average concentration and entrainment of binary mixture particles in freeboard were measured in a ф500 mm×12500 mm large scale cold model perspex experimental equipment,and according to the axial average concentration in freeboard the transport disengaging height（TDH）of binary particle could be obtained.It was indicated that TDH of binary mixture particles increased with increasing superficial velocity and mass fraction of fine particles.The increase of TDH with increasing mass fraction of fine particles was the least when mass fraction of fine particles was near 0.4.Entrainment of binary mixture particles in freeboard increased with increasing superficial velocity.When superficial velocity was less than 0.6 m·s^-1,the increase of entrainment was prominent;moreover,when superficial velocity was more than 0.6 m·s^-1,the trend of the increase of entrainment of binary particle was weak.When superficial velocity was less than 0.5 m·s^-1,the increase of entrainment of binary particle with increasing mass fraction of fine particles was not obvious;when superficial velocity was more than 0.5 m·s^-1,entrainment of binary particle increased with increasing mass fraction of fine particles.According to the analysis of experimental data,a mathematical model of TDH of binary particle was established.Calculated values were in good agreement with experimental values.