This kind of filter can be divided into intermittent operation and continuous operation. All these measures can speed up the filtration.
Negative pressure is formed at the outlet of the filtrate as the driving force of the filtration.
Intermittent-operated filters have been developed because they can complete automatic operation, and the filtering area is getting larger and larger. When the solid particles in the suspension are large and the particle size is uniform, the pore of the filter slag layer is relatively smooth, and the velocity of the filter through the filter slag layer is relatively high. This kind of filter can be divided into intermittent operation and continuous operation of belt vacuum filter. Intermittently operated tubular pressure filters and pressure vane filters are used for filtration of low concentration suspensions. Belt vacuum filters, inner drum vacuum filters and dump vacuum filters are all used to feed the upper part of the filter media (filter cloth), especially for suspensions with high density of solid particles and fast settling. Pressure filtration is commonly used for suspension with high concentration of solid particles because of the small volume of the filter chamber or the application of mechanical pressing force to stop filtering, and the low moisture content of the filter residue. The structure of the belt vacuum filter is similar to that of the belt conveyor. It has a continuous filter belt and is suitable for suspension which is easy to filter. Press filter is also a kind of intermittently operated pressure filter, which can be divided into three types: plate-frame type, box type and vertical type. It is very useful.
The pressure formed by the gravity and potential difference of the suspension on the filter medium is used as the thrust force of the filter, and it is usually operated intermittently, such as a sander. Intermittently operated vacuum filters can filter suspensions of various concentrations. Continuously operated vacuum filters are suitable for filtering thick suspensions containing more solid particles. Because of the complex structure, less application. Oil filter is a plate and frame press unit equipped with oil pump, vacuum evaporator and other accessories. The suspension vacuum filter participates in the upper chamber and enters the lower chamber through the filter medium under the action of pressure. The solid particles are intercepted on the surface of the filter medium to form the filter residue (or filter cake).
We all know that the filter is an indispensable installation in the delivery medium pipeline. It is usually installed at the entrance of pressure relief valve, pressure relief valve, constant water level valve or other equipment to eliminate impurities in the medium, so as to maintain the normal operation of the valve and equipment. Each filter chamber rotates one circle to complete the whole process of filtering operation, and the operation of multiple filter chambers is connected to form continuous filtering. The filtrate is sucked out by the catheter, and the filtrate residue accumulated on the surface of the filter blade is removed after shutdown.
Fine filter is a needle for filtering accuracy, generally between sand filtration (coarse filtration) and ultrafiltration. In belt press filter (see belt vacuum filter), the wet filter residue after preliminary dehydration by gravity or vacuum is clamped between two filter belts and then extruded by roller.
In the process of practical filtration, the three ways are often presented simultaneously or successively. The whole filter surface is divided into several separated filter chambers. Each rotary filter chamber is connected with each fixed pipe through a distribution valve in order to suck out the filtrate, lotion or feed into the compressed air in the filter chamber. At present, the manufacturers of consumer filter equipment in China are mainly small and medium-sized enterprises.
There are three ways of suspension filtration: slag layer filtration, deep layer filtration and sieve filtration. Increasing the pressure difference can accelerate the filtration, but the deformed particles are easy to obstruct the pore of the filter medium when the pressure difference is large, and the filtration is slowed down. When the filter chamber fills with filter residue or the filtration speed is too small, stop the filtration, remove the filter residue, and regenerate the filter medium to complete a filtering cycle.
Fine filters are often used as maintenance filters installed by electrodialysis, ion exchange, reverse immersion and ultrafiltration. They can be applied to water treatment in food, alcohol, pharmaceutical, chemical and electronic industries, such as food industry: fine filtration of mineral water, cleaning and filtering of beverages and alcoholic drinks. Vacuum filters made of continuous rubber belt filters are suitable for filtering thick suspensions containing more solid particles than vacuum belt dewaterers. The coagulant is used to synthesize the fine particles into larger aggregates, which is conducive to improving the filtration rate.
According to the different methods of obtaining the filter propulsion, the filter can be divided into three categories: gravity filter, vacuum filter and pressure filter. The temperature of suspension should be lower than the vaporization temperature of filtrate under vacuum. The screw press filter has a cylinder with holes, among which there are rotating spirals with varying depth of spiral groove. Material is pushed from the deep groove end to the shallow groove end. The space of the filter chamber decreases gradually. Material is squeezed, filtrate is discharged from the hole of the cylinder, and filter residue is discharged from the small end.
The second function of the filter is that the filter can effectively remove particulate pollutants whose size is close to the dynamic oil film thickness of the key motion pair of the vacuum filter. Intermittently operated vacuum filters can filter suspensions of various concentrations. The built-in filter elements include PE core, honeycomb core, folding core, titanium tube sintered core, activated carbon core, ceramic core, polypropylene dilute fiber filter core, etc. At present, the precision range of fine filters in the market is 0.2-100um. Water Disposal Filter
It uses the pressure exerted at the entrance of suspension or the mechanical pressing force exerted on wet material as the filtering propulsion force. It is also used to appeal for the suspension with larger filtration pressure difference. It can be divided into intermittent operation and continuous operation.
The resistance of liquid must be restrained through the filter residue layer and the filter medium, so there must be pressure difference on both sides of the filter medium, which is the driving force to complete the filtration. The working principles of drum vacuum filter, inner drum vacuum filter, disc vacuum filter and dump vacuum filter (Fig. 6) are similar. Now let's talk about the main function of the filter in detail.