WO1982003340A1

WO1982003340A1 - Fabric filter for cleaning of dustladen gases by filtering on filter cassettes

Info

Publication number: WO1982003340A1
Application number: PCT/SE1982/000052
Authority: WO
Inventors: Innovation Adl
Original assignee: Glindsjoe Gunnar
Priority date: 1981-04-01
Filing date: 1982-02-23
Publication date: 1982-10-14
Also published as: DE3239724A1; NL8220037A; JPS58500471A; GB2108405B; EP0075558A1; GB2108405A

Abstract

A construction of a fabric filter for cleaning of dust-laden gases by filtering on filter cassettes (2) and by their regular cleaning with cleaning air comprising a chamber for dirty gas (1), to which is lead dust-laden gas, which is separated to a chamber for clean gas (3), which comprises a number of chambers (10) for delivering of cleaning air and cleaned gas, which in one end comprise one opening for cleaning air (11) and one opening for clean gas (12) and in the other end one opening which is connected directly to the filter cassette. The filter is characterised in that the filter cassette (2) comprises a triangular cassette chamber (6), which partly is performed to collect the cleaned gas and partly has the purpose to lead cleaning air at cleaning and whose opening is performed to connect directly to the chamber (10) whithout any change in the gas flow area and of which the cleaning and shut off of cleaned gas is arranged to happen simultaneously by a common valve blade (13), which is arranged to change from opening (11) to opening (12), at which the filtering is arranged in such a way that the valve blade (13) is given a slow return from the opening (12) to the opening (11). The filter cassette (2) consists of a number of bags (4), which are attached to each other along one side and stretched by a cage (5) with four wires and of which the upper ends are connected to a triangular cassette chamber (6), the end of the cassette chamber (6) is performed to connect to the chamber (10) and tighten to a chamber wall (21) by a packing (9) due to the packing power, which will come into existence, when the cassette (2) is arranged to be hanged by hooks (7 and 8).

Description

Fabric filter for cleaning of dustladen gases by filtering on filtercasettes

This invention relates to a construction of a fabric filter for cleaning of dustladen gases by filtering on filtercasettes and by their regular cleaning with cleaning air comprising a chamber for- dirty gas, to which is lead dustladen gas, which is separated to a chamber for clean gas, which comprises a number of chambers for delivering of cleaning air and cleaned air, which in one end comprise one opening for cleaning air and one opening for clean air and in the other end one opening which is connected directly to the filter casette

When cleaning fabric filters so called pulscleaning has been more and more dominant as this method offers the best cleaning intensity and therefor also a bigger filterratio and a more compact filter. To achieve pulses with enough intensity com¬ pressed air is to be used, which is blown into the bag or filtercassette. Pulscleaning by compressed air has certain disadvantages for instance: an extra valve has to be used to shut off the gasstream when the cleaning is done off-stream, the cost of power is relatively high as only a few percent of the pressure of the compressed air is used for the cleaning- puls, compressed air components and compressor compose a big part of the total filtercost.

The- pulscleaned fabric filter according to the invention makes it possible to achieve the same cleaning intensity as filters • cleaned by compressed air, but the cleaning air is received from a high pressure fan ( 5-10 Kpa) . At the pulsing a shut- of of the gasflue is also received by the pulsingvalve so that cleaning is made off-stream which means lower pressure drop over the filter aterial owing to a less redeposition of dust on this just after cleaning. If a valveblade used for cleaning returns slowly also the filtermaterial returns slowly to its bagcage which diminishes the wear of the filtermaterial and. the outgoing dustburden. Changing filterelements on com¬ pressed air cleaned filters may be time-consuming as the pipes which lead the compressed air to the filterelements often must be taken away at first.

When attatching the filterelements to the filter it is often difficult to achieve enough packingpower. According to the in¬ vention the purpose of the construction is also to bring about an easy change of the filterelements, even and high packing- powers and a short packingline in proportion to the quantity of filterarea and is characterized from what is apparent in the enclosed patentclaims.

The invention will now be described more closely with reference to the enclosed figures where figure 1 shows the fabricfilter according to the invention in vertical view, figure 2 shows horizontal view A-A of figure 1, the figures 3-5 show a filter- cassette and its attatching to the filter where figure 5 is a view B-B of figure 3, and figure 6 shows how a rapid opening of a valveblade can be arranged.

When cleaning gases from dust in a fabric filter the working process can be described according to figure 1. The gas enters the chamber for dirty gas where it distributes around the filterelements on the filtercassette 2 whose filtermaterial the gas penetrates and the dust remains on this filtermaterial. Thereafter the gas enters the chamber for clean gas 3 and from there it leaves the filter. At certain .intervals the filter material is cleaned from dust and then the dust falls into a dustbin. The filtration is made through a number of filter- elements or filtercassettes 2 which are attatched to the wall of the chamber for dirty gas. Every filtercassette 2, fig.3-5, comprises of a number of bags 4 with cages 5. The bags are fixed to each other in a row and the upper part of them are attatched to the cassettechamber 6 which has two triangular sides and is performed so that the streaming of both cleaned gas and cleaning gas in to be made in the best possible way. The fastening of the cassette is made by hanging this in the hooks 7 and 8 and the weight of the cassette and a suitable per¬ formance of the hooks make it possible to receive an even packing power between the cassette and the chamber wall 21 where a packing 9 also is attatched. When the cassette is to be removed it is rotated around the line of contact of the hooks until it is free. When the cleaned gas has left the cassett 2 it enters the rectangular chambers 10 which are fixed in the chamber for cleaned gas in rows. Such a chamber is supplied with two openings or valveseats 11 and 12, a valveblade 13 which serves two valveseats or openings and a inletopening for cleaning air 14 (see fig. 2). When the cassettes are filtrating each valveblade closes against an airreservoir 15 via the openings or valveseats 11 at the same time as the cleaned gas leaves the chamber via the opening 12 and thereafter enters the lower part of the clean gas chamber 3 from where the gas^' leaves the filter.

The cleaning is apparent from figure 1 and 2 where the 1:st, 3:rd and 4'-th cassettes are filtrating while the 2:nd casette is cleaned. When cleaning the valve blade 13 is opened by means of the force from the high overpressure in the air¬ reservoir 15. This can be done very rapidly as a fairly force is working at the valveblade 13. When this is spaced out the flue to the cassette is shut off and and the cleaning gas flushes rapidly into this cassette where a cleaning pulse is formed by the pressure of stagnation and cleans the filter- material. The valveblade then fairly slowly returns to the original position so that also the filtermaterial will slowly return to- the cage of the cassette which will give a lower outgoin dustburden. It is^* also possible to very the cleaning to a great extent due to dustcategory, from pulscleaning for hardcleaned dust to reverse air-cleaning for the categories of dust where this is most suitable.

Figure 6 shows the rapid opening of a valveblade and its slow return. The pneumatic cylinder 16 with its piston 17 works upon the valveblade 13 via the links 18 so that the power from the cylinder balance the power on the valveblade and the packing power from the packing 9. When the cylinder is qjii£Jllγ evacuated the valveblade opens very quickly. Compressed air from the pipe 19 inflates the cylinder via the throttling

20 and the valveblade- closes slowly to achieve the advantages mentioned above.

Of course the invention is not limited to this performance but can certainly be varied within the scope of the inven- tionidea.

OMPI

Claims

a en c a ms

I- Fabric filter for cleaning of dustladen gases by filtering on filtercasettes (2) and by their regular cleaning with clean¬ ing air, comprising a chamber for dirty gas (1), to which is lead dustladen gas, which is separated to a chamber for clean gas (3), which comprises a number of chambers (10) for deli¬ vering of cleaning air and cleaned gas, which in one end com¬ prise one opening for cleaning air (11), and one opening for clean gas (12), and in the other end one opening which is con¬ nected directly to the filtercasette (2) , characterized in that the filtercasette (2) comprise a triangular casettechamber (6) , which partly is performed to collect the cleaned gas and partly has the purpose to lead the cleaning air at cleaning and whose opening is performed to connect directly to the chamber (10) without any change in the gasflowarea and of which the cleaning and shut off of cleaned gas is arranged to happen sim¬ ultaneously by a common valveblade (13), which is arranged to change from opening (11) to opening (12), at which the fil¬ tering is arranged in such a way that the valveblade (13) is given a slow return from the opening (12) to the opening (11).

2. Fabric filter in accordance with patent claim 1, charac¬ terised in that the valveblade (13) and respectively opening (11 or 12) are performed in a rectangular shape, where the long side is more than twice the length of the shorter one and where the driving power on the valveblade, when this is arranged to open from the opening (11) for cleaningair , is arranged to be reached by the relative overpressure, which the atmosphere or an airreservoir (15)._. is arranged to form relatively the chamber (10).

3. Fabric filter in accordance with patent claiml , charac¬ terised in that the chamberarea for the flue of the cleaning¬ air is not less than the inletarea of the casette (2) and the opening (11) for cleaningair, that the chamber (10) is connec¬ ted to the atmosphere or the airreservoir (15) and that the more narrow end of the chamber (10) is to be connected to the opening of the casette (2) and that the area of this is the same as the inletarea of the casette (2) .

4. Fabric filter in accordance with patent claim 1, charac¬ terised in that the filtercasette (2) consist of a number of bags (4) , which are attatched to each other along one side and stretched by a cage (5) with four wires and of which the upper ends are connected to a triangular casette- chamber (6) , the end of the casettecha ber (6) is perfor- - med to connect to the chamber (10) and tighten to a chamber- wall (21) by a packing (9) due to the packingpower, which will come into existence, when the casette (2) is arranged to be hanged by hooks ( 7 and 8 ) .

5. Fabric filter in accordance to some of the claims 1-4, characterised in that the valveblade (13) is arranged to quickly be opened by a quick evacuation of a cylinder (16 ), at which the valveblade is arranged to be shut, through the force from the cleaningair and the packing is balanced by the force from the cylinder (16) via a piston (17) and a link (18), besides which a slow return of the valveblade (13) is arranged to be achieved, when the cylinder again is filled via a throttle (20) .