Membrane assisted fluidized bed reactor: Hydrodynamics, heat transfer and reactor demonstration

目的：该项目的目的是通过在流化床中集成膜来开发一种新型反应器，这种反应器将能够完全控制由限制反应物的可控打瞌睡产生的反应热（例如，部分氧化反应中的氧气智能打瞌睡），或通过选择性去除其中一种产物（例如脱氢反应中的氢去除）来增强对所需产物的转化和选择性。这也将使流化床中气泡到乳液的传质和管到床的传热达到最佳平衡。操作步骤：不同结构（垂直或水平）的微孔非选择性膜将集成在鼓泡流化床中。膜的存在以及气体通过膜的加入或去除对气泡大小、气泡到乳化液传质、乳化液孔隙度、乳化液热容量和管床传热系数都有显著影响。在不同流化速度下，膜的存在和气体通过膜的加入或去除对气泡尺寸变化的影响将通过压力波动测量进行研究。同样，将使用光纤探头测量对乳化液相孔隙率、乳化液中固体浓度、传热表面气膜厚度、乳化液包换热表面更新率的影响，并通过同时测量传热来确定这些特性对浸入式地床换热的影响。最后，将演示乙烯部分氧化为环氧乙烷的反应器概念，并通过开发包含通过膜的气体添加的现象学模型来预测实验结果。在常规流化床反应器上进行了实验，作为参考。

Objective:The objective of the project is to develop a new kind of reactor by integration of membranes in the fluidized bed, which will either enable full control of the reaction heat generated by controlled dozing of the limiting reactant (e.g. smart dozing of oxygen in partial oxidation reactions) or enhanced conversions and selectivity to the desired product by selective removal of one of the products (e.g. hydrogen removal in dehydrogenation reactions), and which will also give an optimal balance between the bubble-to-emulsion mass transfer and the tube-to-bed heat transfer in the fluidized bed.Procedure:Microporous non-selective membranes with different configurations (vertical or horizontal) will be integrated in the bubbling fluidized bed. The presence of membranes as internals as well as addition or removal of gas via the membranes can have significant effect on the bubble size, bubble to emulsion mass transfer, emulsion porosity, emulsion heat capacity and tube-to-bed heat transfer coefficient. The effect of presence of membranes and the gas addition or removal via the membranes on the bubble size variation at various fluidization velocities will be studied using pressure fluctuation measurements. Similarly, the effect on the emulsion phase porosity, solid concentration in the emulsion, thickness of the gas film at the heat transfer surface, heat transfer surface renewal rate by emulsion packet will be measured using optical fiber probe and effect of these properties on the immersed surface-to-bed heat transfer will be determined by simultaneous measurements of heat transfer. Finally the reactor concept will be demonstrated for partial oxidation of ethylene to ethylene oxide and the experimental results will be predicted by developing phenomenological models incorporating gas addition via the membranes. Experiments with conventional fluidized bed reactor will be carried out as reference.