陶瓷膜气固分离中滤饼形成机理及控制方法

Particulate matter 2.5(PM2.5) is one of the main sources of air pollution. Ceramic membrane filters are of major importance in hot gas filtration due to their high filtration efficiencies. Based on the understanding of membrane fouling, which restrict the industrical application of ceramic membrane filter,this proposal is to make fundamental investigations on the ceramic membrane filter using the flow field in the filter as the model. A major emphasis will be placed on understanding of formation and removal of the filter cake and promoting industrial application of ceramic membrane filter. This study will involve the following tasks: 1) Filter cake formation process：With the dynamic observation of filter cake growth process and stress analysis of particulate, calculation models of pore plugging and cake formation are established; 2)Mass transfer structure model: A model combining the effect of membrane pore size and particulate size is developed to predict separation performance of the membrane; 3)Removal of filter cake: Based on the experimental study and computational fluid dynamics method, a symmetrical numerical model is set up to simulate the flow field involved in the filter. A quantitative prediction model is established to predict the pulse cleaning efficiency based on the structure of the filter and the operating conditions.

PM2.5是雾霾天气的主要原因之一，窑炉燃烧过程产生大量的超细粉尘污染物，迫切需要提高除尘效率。陶瓷膜可100%去除窑炉尾气中的PM2.5，但膜污染问题限制了陶瓷膜除尘技术的规模化应用。本项目以陶瓷膜分离器中气固两相流场为研究对象，通过流体力学研究，分析膜污染形成机理，提出污染控制方法，推进陶瓷膜在脱除窑炉尾气中PM2.5的应用。主要研究内容如下：1）滤饼的形成过程研究：动态观察滤饼生长过程，对颗粒进行受力分析，建立孔堵塞和滤饼形成的计算模型；2）传质结构模型研究：测定膜孔径、粉尘粒径等对膜分离性能的影响，建立面向除尘体系的膜微结构和性能的关系模型；3）滤饼去除方法研究：通过实验和CFD模拟计算相结合的方法，研究膜分离器中的速度场和压力场，分析流场变化对滤饼形成和去除机理的影响，结合脉冲反吹实验，建立基于分离器结构、操作条件等多因素耦合的脉冲反吹效率的预测模型，提出控制膜污染的方法。

本申请项目以陶瓷膜气固分离器中的气固流场为研究对象，对高温条件下陶瓷膜分离PM2.5过程中滤饼的形成和去除过程进行研究，分析了流场变化对滤饼形成和去除机理的影响；系统研究了脉冲反吹过程，优化了陶瓷膜气固分离器的结构，优化操作条件，控制滤饼的生长，提高了反吹效率，解决了影响陶瓷膜气固分离器长期稳定运行的膜污染问题，并将研究成果推广到膜法气固分离产品回收过程以及气固膜反应器中用于二甲基二氯硅烷的合成，促进了陶瓷膜气固分离器的工程化应用。