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

目的：该项目的目标是开发一种新型的反应器，通过在流态化床中集成膜，能够完全控制通过控制极限反应物的打瞌睡(例如，在部分氧化反应中智能打瞌睡)产生的反应热，或者通过选择性地去除其中一个产物(例如，脱氢反应中的氢气去除)来提高转化率和对所需产品的选择性，这也将使沸腾床中的气泡-乳状液传质和管床-床层传热之间达到最佳平衡。工艺：在鼓泡床内集成不同构型(垂直或水平)的微孔非选择性膜。作为内件的膜的存在以及通过膜添加或去除气体对气泡大小、气泡到乳状液的传质、乳状液孔隙率、乳状液热容和管床换热系数都有显著的影响。在不同的流态化速度下，膜的存在和气体的添加或去除对气泡尺寸变化的影响将通过压力波动测量来研究。同样，利用光纤探头测量乳化液相孔率、乳状液中固体浓度、传热面气膜厚度、乳化液包换热面更新率的影响，并通过同时测量传热学来确定这些性质对浸没表面-床层换热的影响。最后，将演示乙烯部分氧化制环氧乙烷的反应器概念，并将通过开发包含通过膜的气体加成的唯象模型来预测实验结果。以常规的沸腾床反应器为例进行实验研究。

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.