异形多通孔催化剂工程研究(III)——12孔及24孔颗粒固定床传热参数测定

Engineering Research of Irregular Shape Catalysts with Through-holes(III)——Study on Heat Transfer Parameters of Fixed Bed Packed with Through-holes Pellets

对两种薄片结构的异形多通孔催化剂颗粒的传热特性进行实验研究。在一可同时测定轴向和径向温度分布的壁冷式固定床中测定了12孔及24孔异形多通孔颗粒的温度分布,利用所测实验数据对拟均相二维模型进行了径向有效导热系数和壁给热系数的计算。将得到的传热参数与雷诺数相关联,并与相似条件下圆柱形及单孔环柱形催化剂颗粒的传热参数进行比较。结果表明,12孔及24孔异形多通孔颗粒能有效改善固定床传热性能。

The irregular shape catalysts are catalysts with through-holes formed by flakes. They can decrease the influence of the internal diffusion and lower the temperature rise in catalyst pellets. They also can strengthen the heat transfer in fixed-bed reactor. In order to get the heat transfer parameters of two kinds of irregular shape catalysts with through-holes, the axial and radial temperature profiles of a wall-cooled fixed-bed packed with 12 or 24 through-holes pellets (internal diameter external diameter height, 12 through-holes:φ7.02mmφ5.26mm6.76mm, thickness of flakes is 0.42mm; 24 through-holes:φ7.22mm φ5.78mm6.80mm, thickness of flakes is 0.3mm) in air flow were measured at the same time. The equivalent diameter of these two irregular shape catalysts was determined by the pressure drop of the fixed-bed packed with the irregular shape catalysts. The radial effective conductivity and wall heat transfer coefficient were calculated by applying two-dimensional pseudo-homogeneous heat transfer model. The heat transfer parameters were correlated as function of Reynolds number Rep as follows. Irregular shape catalyst with 12 through-holes: pfswpfer0099.05589.5 ,1018.0214.18RekdkRekk+=+= Irregular shape catalyst with 24 through-holes: pfswpfer0047.08466.6 ,0831.0352.15RekdkRekk+=+= Compared with the fixed-bed packed with cylindrical pellets or cylindrical pellets with single through-hole under the same condition, the heat transfer parameters of fixed-bed packed with through-holes pellets are higher.