Plate and frame filter press machine   

 Filtering mechanism

The filtering mechanism consists of the filter plate, filter frame, filter cloth and the press diaphragm. Filter cloth is used to cover on both sides of the filter plate. When the pressure diaphragm needs allocating, one group of filter plate includes the diaphragm plate and the side plate. Rubber diaphragm is used to cover on both sides of the substrate of the diaphragm plate while filter cloth is covered outside the diaphragm. The side plate belongs to the common filter plate. The materials come into different filter rooms by means of the feeding hole of the thrust plate and the solid particles are closed in the filter room since diameter is larger than the aperture of the filter media (filter cloth). The filtrate outflows from the outflow liquid hole at the lower part of the filter plate. When the filter cake needs draining, beside the diaphragm press is used, compressed air or steam are adopted to enter from the washing port. The flow eliminates the moisture in the filter cake to reduce the moisture content in it.

1. Filter mode: the outflow mode of the filtrate includes the free current and undercurrent filter.

a. Free current: nozzle is established in the outflow liquid hole at the lower part of each filter plate and the filtrate directly outflows from the nozzle.

b. Undercurrent: outflow liquid channel hole is established in the lower part of each filter plate. the outflow liquid hole of several filter plats connect one outflow liquid channel and discharged by the pipelines connected by the outflow liquid holes in the lower part of the thrust plate.

2. Washing way: when the filter cake needs washing, there is free current bidirectional washing and single washing or undercurrent bidirectional washing and single washing.

a. Single washing of the free current is, the washing liquid enters from the washing hole of the thrust plate, runs through the filter cloth and filters cake, and finally outflows from the non-hole filter plate. at this time, the outflow liquid nozzle of the hole plate will be in closed status while that of the non-hole plate will be in the start status.

b. The bidirectional washing of the free current is washing for twice is carried out after the washing liquid comes into the washing inlet hole on both sides from the upper side of the thrust plate, that means the washing liquid washes on one side following with the other. The washing inlet and outlet are in diagonal direction, therefore, it is also called bidirectional cross washing.

c. Single washing of the undercurrent is, the washing liquid enters the hole plate from the washing inlet hole of the thrust plate, runs through the filter cloth and filter cake, and finally outflows from the non-hole plate.

d. Bidirectional washing of the undercurrent means the washing liquid carries out washing for twice after entering the two washing inlets from both sides of the upper of the thrust plate, which means wash is executed from one side first following with the other. The washing inlet and outlet are in diagonal direction, therefore, it is also called bidirectional cross washing.

3. Filter cloth: filter cloth mainly refers to the filter media. The selection and application of the filter cloth exerts a decisive function for the filtering effect. The proper materials and aperture of the filter cloth shall be selected according to the PH value of the filter materials, solid particle and other factors so as to guarantee low filtering cost and high filtering efficiency. Under aplication, the filter cloth shall be ensured evenly with smooth aperture and without unfolding.

 Filter cloth, materials and performance parameter