气液固逆流三相湍动床局部相含率的分布

应用微电导探针测试技术,对聚乙烯颗粒(dp=4.01 mm,sρ=926 kg.m-3)为固相,水、质量分数0.05%和0.2%羧甲基纤维素钠(SCMC)水溶液为液相,空气为气相的逆流三相湍动床的各相局部含率进行了同时测定,获得了720套局部相含率实验数据。在表观气速Ug等于Ug3(颗粒在轴向均匀分布时的表观气速)时实验发现,局部固含率(εs)呈现床中心处小,床壁处大的分布规律,且在r/R=0.75~0.90范围内有极大值,极大值出现的范围与传统流化床相比增大;局部气含率(gε)呈现床中心处最大,床壁处最小的分布规律,与传统流化床相比,gε在径向上的非均匀性分布愈加明显。另外,建立了局部含率与操作条件、流体物性及径向位置的关联式,关联式的计算值与实验值吻合较好。

Distributions of Local Phase Holdups in an Inverse Three-phase Turbulent Bed

Local phase holdups in an inverse three-phase turbulent bed are measured by a micro-electrical conductivity probe technique.The experiments were carried out with polyethylene particles,air,and water,0.05 %(mass) SCMC,0.20 %(mass) SCMC as solid,gas and liquid phases,respectively.720 sets of experimental data of local phase holdups in radial direction are collected under Ug=Ug3.It has been found that the distributions of local solid holdup in radial direction have a minimum value at the column center and a maximum value near the wall region,where a maximum peak is at r/R=0.75～0.90.The range of appearing maximum peak is larger than that of conventional fluidized beds.However,the distribution of local gas holdup is characterized by a reverse trend.The correlation of local phase holdups is a function of operation conditions,fluid physical properties,and radial positions.The calculated values have good agreement with those measured experimentally.