1. Overview of Diaphragm filter press
The Diaphragm filter press has the advantages of high pressing pressure, good corrosion resistance, convenient maintenance, safety and reliability, and is the first choice for customers in metallurgy, gas, papermaking, coking, pharmaceutical, food, brewing, fine chemicals and other industries.
Diaphragm filter press have been widely used in various fields where solid-liquid separation is required. The diaphragm filter press is considered to be an alternative upgrade to the ordinary chamber filter press.
Diaphragm filter press shows good results in terms of treatment capacity per unit area, reducing the moisture of the filter cake, and adaptability to the nature of the processed materials.
The main difference between the Diaphragm filter press and the ordinary chamber filter press is that two elastic membranes are installed on both sides of the filter plate (the composite rubber diaphragm is an integral diaphragm), during operation, when the feeding is over, the high-pressure fluid medium can be injected into the diaphragm plate, then the whole diaphragm will bulge, press the filter cake, so as to achieve further dehydration of the filter cake, that is, press filtration.
Diaphragm filter press is used in sludge, sewage treatment, the lowest moisture content of the filter cake has been less than 60%, compared with the traditional chamber filter press, the solid content of the filter cake can be increased by more than 2 times, the cost of filter cake transportation is greatly reduced, the filter cake can enter the power plant for direct combustion, and the sludge will be turned into resources, sewage into a clear spring, completely replacing the box filter press.
2. Diaphragm classification:
For different diaphragm materials, the new generation of diaphragm filter presses can be divided into rubber diaphragm type and polymer elastomer diaphragm filter press.
Rubber diaphragm filter press is ideal for filter materials with weak acids, weak alkalis, and non-organic solvents. Rubber diaphragm filter press changes the past split fixed type to save energy consumption after feeding, the new design makes the rubber diaphragm eardrum more sufficient, the pressure and air volume used are relatively small, in the case of the same air source air volume, rubber diaphragm tympanic membrane is three times the polymer diaphragm eardrum, can greatly reduce energy consumption.
Polymer elastomer diaphragm filter press is used in strong acid, strong alkali and organic solvent materials, the performance is relatively more ideal, and the service life is longer. Its pressing forms are divided into gas (air) pressing and liquid (water) pressing, which can meet the needs of different industries. According to customer needs, the pressing components can be configured with food grade and ordinary grade, and the control can adopt PLC and man-machine interface. For general materials, after 3-15 minutes of diaphragm tympanic membrane, the role of pressing and dehydration can be fully exerted. For some special materials, the segmented pressing method of first low-pressure pressing and then high-pressure pressing can also be adopted.
The diaphragm filter press realizes the filtration process of efficient dewatering, and can ensure that the filter press exerts the best filtration effect, which greatly reduces the moisture content of the filter cake. At the end of the feeding process, the dewatering efficiency of the whole machine is improved by pressing the filter cake, increasing the dryness of the filter cake, reducing contamination and reducing labor, and even eliminating the drying process in some processes.
3. Working principle of diaphragm filter press:
The main difference between the diaphragm filter press and the ordinary chamber filter press is that an elastic membrane diaphragm plate is installed between the filter plate and the filter cloth. During operation, when the feeding is finished, the high-pressure fluid medium can be injected between the filter plate and the diaphragm, and the whole diaphragm will bulge and press the filter cake, so as to achieve further dewatering of the filter cake, that is, press filtration.
The first is positive pressure strong pressure dehydration, also known as slurry dehydration, that is, a certain number of filter plates under the action of strong mechanical force is closely arranged in a row, filter plate surface and filter plate surface between the formation of a filter chamber, filter material in a strong positive pressure is sent into the filter room, into the filter room of the filter material its solid part is trapped by the filter medium (such as filter cloth) to form a filter cake, liquid part through the filter medium and discharge from the filter chamber, so as to achieve the purpose of solid-liquid separation, with the increase of positive pressure pressure, solid-liquid separation is more thorough, but from the perspective of energy and cost, Too high positive pressure is not cost-effective.
After the slurry is fed and dewatered, the filter press equipped with a rubber extrusion membrane is equipped with a compressed medium (such as gas and water) into the back of the extrusion membrane to push the extrusion membrane to further dehydrate the extrusion filter cake, which is called extrusion dehydration. After the slurry dewatering or extrusion dehydration, the compressed air enters the filter chamber on one side of the filter cake to penetrate the filter cake, and carries liquid water from the other side of the filter cake through the filter cloth to discharge the filter chamber and dehydrate, called wind blowing dehydration. If both sides of the filter chamber are covered with filter cloths, the liquid part can be discharged from the filter chamber through the filter cloths on both sides of the filter chamber, and the filter chamber is dehydrated on both sides.
After the dehydration is completed, the mechanical pressing force of the filter plate is released, the filter plate is gradually pulled apart, and the filter chamber is opened separately for cake unloading as a major working cycle. According to the different properties of the filter material, the filter press can be set up with slurry dewatering, extrusion dewatering, wind blowing dewatering or single-sided and double-sided dewatering, the purpose is to minimize the moisture content of the filter cake.