FI78843B - FOERFARANDE FOER RENGOERING AV FILTERTYGET I ETT KAMMARFILTER SAMT KAMMARFILTER ENLIGT FOERFARANDET. - Google Patents

Description

78843

METHOD FOR CLEANING A CHAMBER FILTER FILTER FABRIC AND A CHAMBER FILTER APPLICABLE TO THE METHOD

The present invention relates to a method for cleaning filter filters in a chamber filter, which method, after opening a substantially vertical filter space between the filter plates and adjoining two opposite filter fabrics, passes a cleaning device with at least one nozzle to direct the compressed air jet them.

Chamber filters are used in industry to separate solids from liquids. Such substances include, for example, cement, coal and ore concentrates. In addition, chamber filters are used e.g. in sewage treatment plants for sludge separation.

The chamber filter comprises a stack of plates formed by vertical filter plates, each of which has a filter space adjacent to the filter cloth. The sludge to be filtered is passed filtered, where it is pressed with a pressing medium passed behind a separate pressing film, such as compressed air, to separate it into the filtrate. The resulting slurry cake can then be washed, if desired, by passing a washing liquid into the filtration space, which is removed by repeating the pressing step. Furthermore, if desired, the slurry cake can be dried with compressed air passed through the space. Finally, the filtration chamber is opened to remove the filtered and treated cake as desired.

In a known chamber filter, the filtration space is delimited on one side by a press film and on the other hand by a filter fabric formed as an endless web guided through rollers arranged above and below the filter plates. The filtered material cake is then removed from the filter space by rotating the filter cloth. In addition, a scraper can be placed near the lower roll below the filter plates, which ensures that the cake comes off the moving fabric.

There are also chamber filters in which the filtration space is limited on both sides to a stationary filter cloth fixed to the filter plate. Such filters are particularly suitable for the treatment of materials which, as a filtered and pressed cake, are said to not adhere to the filter cloth but to detach and fall out of the filtration space when the filter plate pack is opened. However, the fall of the cake has had to be assisted, if necessary, by either manual or automatic measures.

In the former known type of filter, the filter fabric is movable, whereby the washing of the fabric can be performed as a countercurrent washing in a closed filtration space. In the latter type of filter, in which the filter cloths are fixed, a mobile cleaning device with cleaning medium nozzles and possibly scrapers is used for cleaning, which can be guided vertically through the opened filter. When such a device cleans the filter plates or between the plates 1 by one, the cleaning is slow and it has not been possible to carry it out often enough in order to use the filter efficiently. However, failure to clean results in deterioration of the filtration properties and shortened life of the fabric.

The object of the present invention is to provide a solution which enhances the removal of the filtered material from the filter cloth and the cleaning of the fabrics, in particular in a chamber filter with fixedly mounted filter cloths. The method according to the invention uses a mobile cleaning device with one or more nozzles in an open filtration space, and the method is characterized in that it is applied in a chamber filter comprising several parallel filtration methods by cleaning filter fabrics delimiting different spaces of the filter simultaneously through 3 78843 ä, which are connected to each other into one 1 fence assembly.

The invention makes it possible to filter the cleaning of the fabrics at any time during the removal of the filtered material, without the cleaning significantly reducing the capacity of the filter.

For scraping, each cleaning device is preferably provided with a scraper located behind the nozzles spraying compressed air in the direction of movement of the member.

In addition to compressed air spraying, the cleaning of the filter fabrics according to the invention can be combined with washing the fabrics with a washing liquid, which can be applied to the fabrics from the same nozzles as compressed air. The cleaning can then be arranged to take place, e.g.

The invention also relates to a chamber filter, the filter fabrics of which can be cleaned by the method described above. The filter comprises, as is known per se, opposite, substantially vertical filter plates, filter cloths covering the plates, a filter space between the plates adjacent to the opposite filter cloths, and means for opening the filters to clean the fabrics from the filtered material, the means comprising at least one compressed air source and at least one scraper to remove the filtered material from the fabrics. The filter according to the invention is characterized in that the filter comprises several parallel filtration spaces between the filter plates and in that each space is provided with cleaning means 1 connected to each other as a single device for simultaneously cleaning the fabrics of each space.

4,78843

In order for the cleaning means to also perform the washing of the filter cloth, the nozzle can still be connected to the washing liquid supply line. The cleaning means are then preferably arranged to move back and forth vertically in the filtration space so that they perform compressed air spraying and scraping of the fabric in the second direction and washing the fabric in the opposite direction.

The invention will now be described in more detail by way of example with reference to the accompanying drawings, in which

Figure 1 shows a chamber filter according to the invention with filter fabrics being cleaned,

Figure 2 shows on a larger scale the parallel filter plates of the filter and the cleaning members located above them with the filter closed,

Figure 3 shows a side view of the head of the cleaning member,

Fig. 4 shows a cleaning member performing compressed air spraying and scraping of filter fabrics in an open filtration space between filter plates, and

Fig. 5 shows a cleaning member corresponding to Fig. 4 performing washing of fabrics in an open filtration space.

Figure 1 shows schematically a chamber filter according to the invention, which consists of vertical filter plates 1 and in which the filter spaces 2 are located between the filter plates. The figure shows the filter open while the filter fabrics delimiting the filter spaces 2 are being cleaned. For cleaning, a cleaning member 3 is connected to each filter plate space, which is connected via the connecting lines 4 to the compressed air line 5 and the washing liquid supply line 6. The rod-like cleaning elements 3 are attached at their ends to the common sides of the filter plates 1 and the filter spaces 2 between them.

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to the beams 7. The beams 7 can be moved vertically on the lifting and lowering mechanisms of chains 8 or the like located at the ends of the filter.

According to Fig. 2, the filter plates 1 are surrounded by a filter cloth 9 so that the filter spaces 2 between the plates are bounded on each side by a filter cloth. The sludge-like material to be filtered is led to the filtration chambers 2, where it forms a solid material cake as the liquid seeps through the fabrics 9 into the outlet channels 10 starting behind them.

As shown in Figures 2 and 3, the rod-like cleaning means 3 comprise a tube 11 connected at its ends to the above-mentioned connecting lines 4 supplying compressed air or washing liquid, nozzles 12 directed obliquely downwards from the tube against the filter fabrics 9 and scrapers 13 and possibly during the subsequent washing and drying of the cake of material, the cleaning means 3 are raised above the closed filtration spaces 2 according to Fig. 2.

In the step of removing the filtered material 14 following the filtration, the filtration space 2 is opened according to Fig. 4 and the cleaning member 3 is moved in the space on the connecting beam 7 and the chains 8 from top to bottom. In this case, the jets of compressed air 15 directed against the filter fabrics 9 from the nozzles 12 remove and drop the main part of the filtered material 14 and the scrapers 13 following them remove the remnants of the material, thus performing a preliminary cleaning of the filter fabrics. In the next step according to Fig. 5, the cleaning member 3 is moved in the filtration state from the bottom up while the washing liquid jets 16 led from the nozzles 12 perform the washing of the filter fabrics 9. Water, for example, can be used as the washing liquid.

When the cleaning means 3 operating in the parallel filtration chambers 2 are connected according to Fig. 1 via a connecting beam 7 78843 into a single unit, the chambers can be cleaned in one operation, where the cleaning means first move from the starting position above the filter plates 1 to the bottom and back to the starting station.

It will be clear to a person skilled in the art that the various embodiments of the invention are not limited to the example given above but may vary within the scope of the appended claims.

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Claims (7)

A method for cleaning the filter fabric (9) in a canister filter, in which the process, after opening a substantially vertical filtration outlet (2) son, is delimited by two opposing filter fabrics, the genon is cleared by a cleaning means. (3) provided with an etching element (12), from which a compressed air jet (15) is directed toward the fabric and down which the fabric is scraped in time to release the filtered material (14) from it, characterized in that the process in a jug filter, a plurality of parallel filtering outlets (2) are connected to the cleaning fabrics (9) which delimit the filter and, in the outflow, down cleaning means (3), so that the genon outlets are simultaneously moved and connected to an apparatus unit. 2. A method according to claim 1, characterized in that in each filtration outlet (2) a compressed air jet (15) extends from the scraper (13). 3. A method according to claim 1 or 2, characterized in that the cleaning means (3) are moved during the compressed air blowing (15) and the scraping from the top down in the filtration outlets (2). 4. A method according to any of the preceding claims, characterized in that the filter fabric (9) is washed down a washing liquid (16) after the compressed air blowing and scraping. 5. A method according to claim 4, characterized in that the washing is performed down said cleaning means (3) genon to bring it down from below up into the filtration outlets (2).