Diaphragm pressure filter is intermittent pressure filtration equipment for solid-liquid separation;
the main difference between diaphragm type and chamber filter press is that a elastic membrane was equipped with between filter plate and filter cloth; while in operation, high pressure fluid goes into chamber between filter plate and the diaphragm after feed finished, then filter cake will be compressed by the expanding membrane, that is pressure filtering which further dewater of the filter cake realized.
Dewatering will begin first under positive pressure of feed pump, that is feed dewatering; a certain amount of filter plates are arranged in line and compressed together tightly by strong mechanical force, there are many filtration chambers, material is pumped into the chambers, solid matter in feed slurry is remained on filter medium (filtercloth) meanwhile filter cake increased gradually; liquid phase is drained out of the filtration chambers passing through filter medium, then solid-liquid separation achieved in this way; usually solid-liquid separation will be more complete with increasing of the feed pressure, however it is uneconomic and unreasonable for too high pressure in consideration of energy consumption and cost.
After feed dewatering process, compressing medium (compressed air or high pressure water) enters into the back of squeezing membrane, then the filter cake is pressed and dewatered again, this is so called press dewatering; after feed dewatering and press dewatering process, compressed air enters into filtration chambers from filter cake side and goes out of the chambers with moisture from another side through filter cake and cloth, that is air blowing dewater; liquid will go out of filtration chambers through filter cloth at both sides of the chamber if filter cloth equipped with at two sides of a plate, this is one chamber with two sides dewatering.
After dewatering process finished, mechanical pressing force is removed, the filter plates are pulled away one by one, the filtration chambers are opened respectively and filter cake in the chambers is discharged, then one main operation cycle finished and another cycle will start again; according to difference material characteristic, feed dewatering, press dewatering, air blowing dewater, single or two sides dewatering process can be set to pressure filter in order to reduce moisture content in filter cake as low as possible.