Development Of The Vacuum Vertical Plate Filters

Cake filtration is a kind of Solid-liquid separation, and includes vacuum filtering and pressing filtering. The solid grains will be blocked by filter cloths on the surface due to the pressure difference on the two sides of the cloths, and then the later solid grains will be blocked sustaining by filter cake composed by former solid grains.The vacuum filtering is isobarically, so according to the Ruth Filtration Equation, the degree of the system vacuum, filtering time, filtering area, filtering medium, the feature of the slurry and the uniform rate of the slurry are main factors affecting the working efficiency of the Vacuum Vertical Plate Filters. By theoretic analyzing, increase the vacuum ratio, improve the uniform rate of the slurry and selecting the suited filtering cloths will improve the filtering efficiency in the certain filtering area. At the same time, by field surveying of the filters working status, there have some structure defects in the existing filters in Chinese domestic application, such as lower rigidity of the filtering plates, being hard to change filter cloths individually in process.According to these analyzing and surveying, the design of the vacuum vertical plate filters was improved to match these effecting factors. To increase the system vacuum ratio, the sealing unit of the joints in the filters was amended to minimize the leakage of the vacuum. And the main driven shaft is specific welding structure to maximize the section area of circulating in certain shaft diameter and minimize the pressure loss. To promote the uniform rate of the slurry and avoid settling in filtering process, some small stirring paddle was added on the excircle of the filtering plates. The selected filtering cloths with merits of higher filtering performance and specific elongation were used in the filters. The filters use higher submerge ratio up to 50% to decrease the blind area. Using a kind of specific fixing structure, the rigid of filtering plate was improved and can change filtering cloths individually.By these design and improvement, the vacuum vertical plate filters have merits of rational structure and higher working efficiency.