水蒸气冷凝胁迫细颗粒运动脱除研究

Fine Particles Removal by Water Vapor Condensation with Diffusiophoresis

针对工业尾气中细颗粒(0.1~10μm)难脱除特性,利用废气废水热力学势差,构建气液交叉流阵列(GLCA)脱除细颗粒新方法。废水经分布板供水,在重力作用下经导流线表面形成连续稳定液相界面流动液膜柱群,尾气横掠液膜柱群,蒸汽冷凝形成边界层,颗粒进入边界层受扩散泳力而被胁迫向液膜柱运动被捕集。对GLCA中单液膜柱建立扩散泳力作用颗粒传质微分方程,得到颗粒脱除效率与水蒸气冷凝量关系。与其他脱除机理进行对比,得出当颗粒粒径0.1~5μm,扩散泳力为主要脱除机理,且脱除效率正比于水蒸气冷凝量,通过增加气液两相湿度梯度,效率可达到80%,粒径为5~10μm,扩散泳力和惯性碰撞为主要机理。对20(列)×100(排)GLCA进行实验,颗粒脱除效率实验结果与理论值较为吻合。

Based on the temperature gradient between exhaust gas and wastewater,a gas-liquid cross-flow array(GLCA)system is proposed to remove fine particles,which are difficult to be removed by traditional technology.In a GLCA,wastewater vertically down flow along a number of configured wires,by which numerous smoothly water films can be formed on the surface of wires.When the exhaust gas proceeds across the films,it will form a stable vapor boundary layer around every film due to vapor condensation,and once particles enter into the boundary layer,they will experience the force of diffusiophoresis(DP)and have the possibility to be captured by the films.An analytical model based on single film is developed to calculate particle removal efficiency of a GLCA,which is a function of the amount of vapor condensation.Compared with other removal mechanisms,DP is the main removal mechanism for particles in the size range of 0.1~5μm,and the efficiency is proportional to the amount of vapor condensation.Moreover,the efficiency can be easily up to be 80%by increasing the humidity gradient.However,DP and inertia are the main removal mechanisms when the particle size is in the rang of 5μm to 10μm.Experiments with a lab-scale GLCA are carried out,and the theoretical results agree well with the experimental data.