板框压滤机是固液分离过程应用较为广泛的一种过滤设备。面对工业化的迅猛发展,为了适应发展的需要,板框压滤机的结构也在进行不断地改善。开发了一种新型动态扫流板框压滤机,通过采用对角切向进料的进料方式以期提高过滤速率、改善过滤效果。文中采用计算流体力学(CFD)方法对对角切向进料板框压滤机滤室内的流动形态进行了模拟研究,得到滤室内的颗粒轨迹、滤饼形成规律。同时,建立了小试实验装置,实验测定了滤室内的颗粒轨迹,并对比分析了新型对角切向进料和传统中心进料的优势。结果表明,利用泵压使流体切向进入滤室圆框内,形成涡流状转动,推动滤布上截留的细小颗粒固体形成的薄层滤饼向涡流中心结集,沿途经过扫流的区域只能形成薄饼,过滤阻力减小,薄饼又被后面的流体带动流向中心区域,过滤初始阶段的过滤速度大为加快。数值模拟得到的滤室内的颗粒轨迹、滤饼形成规律、过滤时间等都与实验测得的基本一致,研究结果为后续进行新型板框压滤机的优化设计提供了依据和方法。
Plate and frame filter press is a filtering device widely used in the solid-liquid separation process. In order to meet the requirement of the rapid development progress of industrialization, the structure of plate and frame filter press is also constantly improved. By adopting diagonal tangential feeding, a new kind of dynamic cross-flow plate and frame filter press was proposed, which can enhance the filtration rate and improve the filtering efficiency. Computational fluid dynamics method was used in the paper to simulate the flow morphology within the filter chamber of the new plate and frame filter press. In the meantime, a small experimental device of plate and frame filter press with diagonal tangential feeding was built to observe the particle trajectory in the new filter and to comparatively analyze the superiority of the new diagonal tangential feeding over the traditional center feeding. The results show that, when using diagonal tangential feeding, under the pump pressure the suspension is tangentially fed into the filter chamber to form a vortex-like rotation, which can promote the thin filter cake comprised of the trapped tiny particles to gather toward the center, while the sweep flow area can only form thin filter cake and then the thin filter cake are taken by the subsequent fluid to the center, so that the filtration resistance decreases and the filtration rate of the initial stage accelerates greatly. The simulation results of the particle trajectory, and the filter cake formation laws within the filter chamber, and the filter time are basically the same as that of the experimental observations, which can also provide a basis for subsequent design optimization of the new plate and frame filter press.