As a band filter, a cleaning device is known in the mechanical filter, which also contains as an essential component is a conveyor belt. In electronics, the bandpass filter is a module that certain frequencies can be preferable to pass.
Band filter in mechanics
Band filters are continuously operating horizontal filters that operate by vacuum or gravity and are used in the mechanical solid-liquid separation. A distinction is made between working with vacuum belt filters and clock Traggurtfiltern and gravity filters.
Band filters are built in sizes ranging from 1 m to over 250 m² filter surface. They are characterized by good filter performance, effective washing facilities for the solid and a good cleanability of the filter medium. Band-pass filter are well-suited for the separation of suspensions having from 3 to 40% solids for particle sizes from 1 micron to 100 microns. The suspension temperature should not exceed 95 ° C. Due to their versatile applicability they come, among others, in the chemical industry, pharmacy, food industry, environmental technology, the color and pigment and mineral industry and mining sites.
A continuous circumferential, elastic shoulder strap is guided between two deflection rollers and forms on the surface by means of lateral ridges a trough-shaped hollow. In the trough runs synchronously an endless filter cloth, which is recycled to the bottom of separate rolls. At the beginning of the tape uniform suspension job done. The filtrate flows by gravity through the filter cloth, or it is sucked through an applied vacuum through this and then discharged. Remains on the filter cloth of the solids and form the filter cake. At the end of the tape separates on the rear guide roller, the filter cloth from shoulder strap. The shoulder strap runs back to the front guide roller. The filter cloth is transferred to a further roller, deflected there, and the filter cake is discarded. Then, the filter cloth is washed and recycled.
Of the guide rollers there is an intensive deformation of the support belt. Therefore, the carrying belt must be made of durable elastic material having sufficient tensile strength. In addition, he is sufficiently chemically, optionally also be thermally stable. Before carrying belts are made of rubber, are now also more stable, easier to clean materials are used. Also, the filter cloth must be resistant to the prevailing chemical and thermal conditions. In addition, the filtration property and the mechanical stability in use can not be changed. Traggurtfilter reach very high solid performance and are particularly suitable for the filtration of suspensions with coarse-grained materials.
Timing belt filter
A rotating textile band, which is moved cyclically or continuously, is used as a filter medium. The suspension is fed uniformly to the tape sucked off, the filtrate down, the filter cake remains on the top of the strip and may then be washed on the filter is extracted, dehydrated, compressed mechanically or thermally dehydrated. At the end of the filter, the filter cloth is deflected on a roll and the filter cake discarded. After the cake removal is done to clean the filter cloth. As the filter cloth of the cake is rinsed, rear, or from both sides.
Clock bandpass filters are constructed depending on the application in metal, stainless steel or plastic version. They can be manufactured with an open frame construction, with a cover to protect against dust and gas or pressure-tight box construction. This different use cases can be covered: from the minerals industry with coarse and abrasive products on the dye industry with very fine particles through to the food and pharmaceutical industries with GMP requirement (Good Manufacturing Practice) and sterile atmosphere.
A distinction clock band filter with stationary and oscillating vacuum cups.
Timing belt filter with stationary vacuum cups
Several usually equal vacuum cups are behind each other on the filter frame and are firmly connected to the vacuum and filtrate system. The length of the tape transport per interval corresponds to the zone length of a vacuum cup. During the power stroke is at a vacuum, the filter cloth is stationary and is fixed by the vacuum and the weight of the filter cake on the support grid to the underlying stationary vacuum bowl. The vacuum is broken with fast opening and closing shut-off and vent the vacuum cups with ambient pressure. Thereby, the filter cloth is released and can be transported further. At the take-off roll, the filter cake is discarded. When the filter cloth has been conveyed to the new zone, the vacuum is reapplied and the next work cycle begins. The cloth cleaning takes place during the band trip transportation.
Timing belt filter with oscillating vacuum cups
The vacuum cups are designed to be movable. A lift cylinder they periodically return to the starting position. By the vacuum and the weight of the filter cake, the vacuum cups are attached to the filter cloth, and move synchronously with the latter in the direction of cake discharge. The shells are connected by elastic filtrate tubes to the vacuum system. A new variant of this type does not require elastic tubing, it has a kind of linear control head on the slide vacuum cups and the oscillating vacuum cups with the static vacuum system combines .. After breaking the vacuum of the lift cylinder moves the vacuum cups back to your starting position, while the filter cloth with variable speed transported continuously. After reaching the starting position of the next work cycle begins. The discharge of the filter cake and the cleaning of the filter cloth takes place continuously.
Gravity filter perform the fully automatic continuous purification of liquids, especially emulsion and oil from the metal processing in normal demands on the purity. An endless Metallgurtband passes between a drive and a deflection roller, serving as the carrier for the actual filter medium. Webbing and filter media form a trough flows into the suspension. On the filter medium, hydrostatic pressure is built up, and the filtrate flows downwardly through the filter medium. On the filter medium, the solid is deposited. The propulsion means of the motor gear, and thus the consumption of the filter medium is controlled by a float switch, depending on the contamination.
The liquid level increases to a maximum level. If this is reached, triggers a float switch from a tape measure. At the same time used filter medium is conveyed in the dirt box and fed fresh. Below the filter, the filtrate is collected and conveyed from there.