气-固环隙流化床纳米TiO_2聚团的流化特性

在高640 mm,内外径分别为140 mm和180 mm的环隙流化床反应器内,选用平均粒径为20～30 nm的TiO2催化剂P25进行冷态流化实验。运用预测颗粒粒径模型,应用计算流体力学软件FLUENT 6.2对流化床内床层局部固含率和压降进行了模拟计算。模拟结果显示:气体进入分布板之后呈螺旋状上升;环隙流化床内径向局部固含率分布呈现W形状,而且局部固含率随着床层高度的增高而增大。模拟结果与实验数据基本一致,说明纳米TiO2催化剂颗粒在环隙流化床中以微米级的聚团形式流化。

Investigation of Fluidization Characteristics for Nano-titanium Dioxide Aggregates in a Gas-solid Annular Fluidized Bed

In this work,cold flow experiments were carried out using nano-TiO2 catalyst P25 in the annulus fluidized bed reactor with 640 mm in height,140 mm inside and 180 mm outside diameter.Local solid holdup and pressure drop were computed to apply model of prediction particle size using computational fluid dynamics software FLUENT 6.2.Simulation results show that the gas flow is in spirals pattern after gas passes through distributor.The radial profiles of local solid holdup are characterized by W shape,and local solid holdup increases with increasing the bed height.The numerical simulations agreed with the experimental data.It is shown that the nano-TiO2 catalysts are fluidized to generate micron-level agglomerates in the annulus fluidized bed reactor.