AU730462B2

AU730462B2 - A flow control member for a filter cartridge cleaning system

Info

Publication number: AU730462B2
Application number: AU44502/99A
Authority: AU
Inventors: Jeff Elliott; George Wilson
Original assignee: Goyen Controls Co Pty Ltd
Current assignee: Goyen Controls Co Pty Ltd
Priority date: 1994-07-28
Filing date: 1999-08-16
Publication date: 2001-03-08
Anticipated expiration: 2015-07-27
Also published as: AU4450299A

Description

P/00/01i1 Regulation 3.2

AUSTRALIA

Patents Act 1990

ORIGINAL

DIVISIONAL PATENT Invention Title: A flow control member for a filter cartridge cleaning system The following statement is a full description of this invention, including the best method of performing it known to us: FHP.SY[N7C\NATffl12()%922O21 .7 CEcone AU Patent.doz 1 A FLOW CONTROL MEMBER FOR A FILTER CARTRIDGE CLEANING SYSTEM Field of Invention The present invention relates to flow control systems for controlling direction, pressure and effect of the airflow utilised to clean filter cartridges in filter cartridge cleaning systems.

Background Art Conventional cartridge filters are generally in the form of elongated cylinders open at one end and closed at the other, and are cleaned by a reverse pulse of air. This air is generally emitted from a blow tube into the open end of each cartridge. Airflow control and direction modifiers such as venturis, although widely used, do not substantially improve on the cleaning effectiveness.

A particular difficulty experienced by such cleaning system is that a portion of the cartridge, particularly that portion closest to the source of reverse flowing air, does not experience any cleaning at all, whereas that portion that is cleaned tends to be over cleaned and becomes cumulatively damaged as a result.

Tests conducted on cartridges in reverse pulse cleaning systems have shown that along the internal length of the cartridge, cleaning pulse pressures vary markedly. Observation shows an excessive positive air pressure is applied to part of the filter which over cleans, whilst at other parts (which are generally closest to the reverse pulse source) are subject to a low or o*o* 20 even negative pressure, which results in a poor cleaning at those parts.

One possible solution to this difficulty is described in German Specification DE4308286A1 of Bissinger GmbH. In this specification there is disclosed the use of a conical element which is interposed between an outlet nozzle and the inlet to a filter cartridge. DE4308286 teaches that the effect of the cone is to produce a sufficient pressure 25 to be built up along the entire length of the filter element. This pressure produces a reverse air flow through the filter element to dislodge particles on the outside of the filter cartridge element.

A conical element similar to DE4308286 has been shown in tests conducted by the applicant to be ineffective as the minimum nozzle orifice diameter increases and the air flow rate increases.

It is unknown as to why such a result occurs, however it does cause a difficulty to the filter cleaning industry in that the cone of DE4308286 is not useful under the current range of conditions that are utilised in the filter cleaning industry.

CEcone AU Patent.doe 2 Other attempted solutions are disclosed in US 4836834 and DE 4242991. In each of these documents there is taught the use of a conical portion which is attached to the cartridge and positioned with in the cartridge. This positioning can be detrimental to the operation of the filter cartridge by blocking the passage of air out of the filter cartridge.

Summary of Invention The present invention provides a flow control member for a filter cartridge cleaning apparatus that utilises compressed air discharged from an air flow nozzle and directed into an open end of a cartridge filter, the flow control member being adapted to be positioned in a cleaning air flow directed toward said open end, said flow control member having a divergent portion having a crest facing the direction of said air flow and a flow redirection surface adapted to redirect said air flow after it has passed over said divergent portion, and means to mount the flow control member upon the nozzle.

The divergent portion can be one of the following: conical; pyramidal; part spherical.

The flow redirection surface can be one of the following: cylindrical; part spherical; a 15 frusto-conical portion; a polygonal prism; a tapered portion.

The air flow redirection surface can extend a distance of between 5 millimetres and millimetres, from the end of the divergent portion.

Preferably a curved surface is present between the divergent portion and the flow redirection surface. The radius of the curved surface is between one millimetre to ten millimetres.

The flow control member is preferably adapted to be clamped to said nozzle. The flow control member can have at least one support arm, with the or each support arm connectable to a clamping ring. The flow control member can include a positioning means Swhich keeps said crest a predetermined distance away from a point of emission of said 25 cleaning air flow from said nozzle.The flow control member can have a cavity adjacent the divergent portion and flow redirection surface.

The divergent portion and the flow redirection surface modify the cleaning air flow so that the internal portions of said cartridge filter are subjected to substantially uniform pressure exerted by said cleaning air flow.

The flow redirection surface can be less divergent than said divergent portion.

The present invention also provides a method of cleaning filter cartridges, said cleaning being performed by means of cleaning air flowing into the filter cartridge in order to remove particles deposited on the outside of a filter cartridge, said method including the provision of uniform air pressure along a substantial area of the internal wall of the filter S lA element being produced by means of a flow control member as described in previous CEcone AU Patent.doe 3 paragraphs. The flow control member can be positioned in the air flow entirely externally of the cartridge filter.

The advantages provided by the features of the invention include the fact that a single flow control member can be provided to improve the efficiency and efficacy of the cartridge cleaning system. Having a single flow control member reduces the inventory and provides a "one part fits all" type retrofitting kit. The use of such a flow control member will also provide monetary and labour savings for the users by reducing the amount of compressed air used to clean the filters as well as increasing the service life of the cartridge filter elements.

Throughout the specification and claims "cone angle" of a cone or a frustrum of a cone, is defined to be that angle formed between two diametrically opposed lines on the surface of the cone or frustrum of a cone, and intersecting at the apex the cone or at the imaginary or theoretical apex of the frustrum, as the case may be.

Brief Description of the Drawings S.Q S An embodiment of the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a diagrammatic side elevation of two prior art arrangements; Figure 2 illustrates a perspective view of an inventive flow control member; Figure 3 illustrates a plan view of the flow control member of figure 2; *•so 20 Figure 4 is a cross section of the member of fig. 3 through line 4-4; Figure 5 is a side view of a clamping member used in fig. 2; Figure 6 is a cross section through the line 6-6 of fig. Figures 7 and 8 illustrate side sectional views of other embodiments of the o invention; Figures 9, 10, 11 and 12 illustrate other flow control members of the present invention Detailed Description of the Drawings In figure 1, the prior art system 1 utilises a venturi 3 to direct compressed air emitted from a hole in a blow tube 13. This system has been tested under normal operating conditions and found to produce a considerable gradation of pressures along the length of the filter cartridge 5, whereby the top 150 to 200 mm of the cartridge is not effectively cleaned.

Cartridges are normally made to either a European or American standard. The American standard are approximately 600 mm in length whereas in the European standard they are 1 aproximately 1000 mm in length.

CEcone AU Patent.doe 4 The gradation of pressures produced in the cartridge filter 5 results in insufficient cleaning or no cleaning of some portions whilst over cleaning others.

Illustrated in figure 2 is a cartridge cleaning nozzle 2 which includes a flow control member 4 having a conical portion 6 and a cylindrical portion 8 which extends away from the base of the conical portion 6. The intersection of the cylindrical portion 8 and the conical portion 6 is rounded having a radius 10. The radius 10 is 5 millimetres but can be in the range of 1 to 10 millimetres.

The cylindrical portion 8 extends approximately 13 millimetres beyond the base of the conical portion 6, measured in the direction of the conical axis, that is that axis that passes through the apex of the cone and the centre of the base. Other distances could be used and depending on the pressures used in the cleaning system and the nozzle sizes a distance of greater than 5 millimetres is appropriate. For most practical purposes it is unnecessary to exceed 25 millimetres, except where constructional features, such as is shown in figures 7 or 8, requires a greater length.

The conical portion 6 and cylindrical portion 8 are formed as a cup-like structure with a hollow interior 12. Interconnecting the hollow interior 12 and the outside surface of the conical portion 6 are four holes 14 which have axes substantially parallel to the conical axis.

Each hole 14 is located approximately equidistant between four legs 16, which extend from the conical portion 6.

Each leg 16 as is illustrated in figures 2 and 3 is approximately 3 mm in thickness. Thinner

S

legs, would less obstruct air flow around them, but are difficult to injection mould. Each of leg 16 has an extension 18 adapted to fit into a mating recess 20 in a clamping collar 22 more clearly illustrated in figures 4 and 5. The clamping collar 22 includes a split 21 which :8 25 allows it to be tightened around the outer diameter of an appropriately sized nozzle.

At the junction of the extension 18 and legs 16 is a shoulder 24. The conical portion 6 has a rounded crest 26 with a theoretical cone apex 28 at a point upstream of the crest 26. The distance between the crest 26 and the shoulder 24 is set to achieve the desired results from the flow control member 4 in the filter cleaning system. This distance is positively set by the shoulder 24 engaging the rim 30 of nozzle 32. ensuring that the crest 26 is kept in use at a predetermined distance (in this instance 20 millimetres) from the exit plane of the blow tube nozzle 32. The clamping collar 22 and the members 18 are then clamped into position by means of a pipe clamp 34. The clamping force tends to force together the portions of the clamping collar 22 on either side of split portion 21. Although the most preferred distance is 20 millimetres, other distances can be utilised, with the preferred distance being in the I r~ange of 10 to 40 mm.

CEcone AU Patent.doc In operation, the cylindrical portion 8 is thought to prevent the separation of air flowing over the conical portion 6 which normally would separate after it had passed the end of the conical portion 6.

The nozzle 32 is secured to a blow tube 13 by means of a strap system (not illustrated) which is then clamped into place. (PCT/AU94/00520 shows the clamping system).

However it will be readily understood that the clamping collar 22 can be selected so that its inside diameter is sized and for attachment to any sized or shaped nozzle which may already be existing and attached to a blow tube.

In figure 2 the flow control member 4 is shown attached by means of legs 16. Alternatively it can be installed outside, in the centre of the opening of a cartridge filter, held by a a support rod (not illustrated)will extending from a central clamping rod (not illustrated) normally used to hold such cartridge filters in position.

The cartridge cleaning nozzle 2 illustrated in figure 2 which includes the nozzle 32, is 15 designed to be retro fitted and be correctly located when used with a cartridge nozzle 2 when the distance 15 (see figure 1)between the blow tube 13 and the filter cartridge 5 is in the range of 300 to 450 millimetres. If the height between the filter cartridge and the blow tube is less than 300 millimetres a different nozzle 32 arrangement or size may be required or alternatively the flow control member 4 could be mounted above the filter cartridge by means of a support extending from the filter cartridge or from its associated clamping oo system.

•o° The cartridge cleaning nozzle 2 of figure 2 is packaged in a kit of parts which make up a retro fitting kit. The kit must include a flow control member and can include a nozzle 32, various sizes of insertable orifices for the nozzle 32 and clamping and securing means for 25 all components.

Another location for a flow control member is in the mouth of the filter cartridge as illustrated in figure 7. In figure 7 the flow control member 4 which includes a conical portion 6 and a cylindrical portion 8 can be constructed as part of, or added to the filter cartridge 5, on the inside of the filter cartridge 5. It will be noted that the cone 6 has its crest 26 above the inlet to the cartridge 5. The flow control member of figure 7 is thus positioned so that air flowing over it exerts a substantially uniform pressure on the internal surfaces of the filter cartridge.

Figure 8 shows an alternative flow control member having a cylindrical portion 8 and a curved divergent portion 36 instead of the conical portion 6 shown in figure 7.

CEcone AU Patent.doc 6 These alternatives partly or fully located inside the filter cartridge, can provide more effective cleaning of filter cartridges, under various rates of air flow, various nozzle geometry or various other flow characteristics.

Illustrated in figures 9 to 12 are other shaped flow control members which operate in the same manner as the flow control member 4 of figure 2. The flow control members 50 each have a conical portion 52 and in figure 9 the flow redirection surface 54 is a convergent curved surface. Preferably the surface 54 of figure 9 terminates so that a tangent to the member 50 at the furthest downstream end is approximately parallel to the axis of the cone 52.

In figure 10 the flow redirection surface 56 is a partially convergent and partially divergent curved surface which also terminates so that the tangent at the furthest downstream end is approximately parallel to the axis of the cone 52.

In figure 11 the flow redirection surface 58 is shown as a convergent frusto-conical surface 15 (tapered inwardly). The angle of the frusto-conical surface 58 is selected so as to ensure that the flow redirection surface 58 will have the desired effect. A divergent frusto-conical surface of a different cone angle to the cone 52 may also achieve the desired effect, however it is envisaged that the cone angle selected for the frusto-conical portion 58 would i• have to be relatively small, for example of the order of 1 to 20 degrees. The maximum cone angle selected for a divergent frusto-conical portion would be determined according to the effect which results.

In figure 12 is a flow control member 60 which has a hexagonal pyramid divergent portion 62 and a hexagonal prismatic portion 64 which acts as a flow redirection portion in much the same way as cylinder 8, curved surfaces 54 and 56, and conical portions 58 and 59 do.

It is envisaged that where a particular divergent portion is selected a corresponding 25 prismatic portion is also selected. For example cone/cylinder (circular prism), hexagonal pyramid/hexagonal prism, square pyramid/rectangular prism. Whilst for ease of manufacture such a combination of shapes would be most desirable, mixed combinations could also be used as flow control members, such as hexagonal pyramid and cylindrical.

Claims

1. A flow control member for a filter cartridge cleaning apparatus that utilises compressed air discharged from an air flow nozzle and directed into an open end of a cartridge filter, the flow control member being adapted to be positioned in a cleaning air flow directed toward said open end, said flow control member having a divergent portion having a crest facing the direction of said air flow and a flow redirection surface adapted to redirect said air flow after it has passed over said divergent portion, and means to mount the flow control member upon the nozzle.

2. A flow control member as claimed in claim 1 wherein the divergent portion is one of the following: conical; pyramidal; part spherical.

3. A flow control member as claimed in claim 1 or 2 wherein the flow redirection surface is one of the following: cylindrical; part spherical; a frusto-conical portion; a polygonal prism; a tapered portion.

154. A flow control member as claimed in any one of the preceding claims wherein the 15 air flow redirection surface extends a distance of between 5 millimetres and 25 millimetres, from the end of the divergent portion. :o 5. A flow control member as claimed in any one of the preceding claims wherein a curved surface is present between the divergent portion and the flow redirection surface. 6. A flow control member as claimed in claim 6 wherein the radius of the curved 20 surface is between one millimetre to ten millimetres. S 7. A flow control member as claimed in any one of the preceding claims wherein the flow control member is adapted to be clamped to said nozzle. 8. A flow control member as claimed in any one of the preceding claims wherein the S: flow control member has at least one support arm. 25 9. A flow control member as claimed in claim 8 wherein the or each support arm is connectable to a clamping ring. A flow control member as claimed in any one of the preceding claims wherein a positioning means keeps said crest a predetermined distance away from a point of emission of said cleaning air flow from said nozzle. 11. A flow control member as claimed in any one of the preceding claims wherein the flow control member has a cavity adjacent the divergent portion and flow redirection surface. 12. A flow control member as claimed in any one of claims 1 to 11 wherein the divergent portion and the flow redirection surface modify the cleaning air flow so that the internal CEcone AU Patent.doc 8 portions of said cartridge filter are subjected to substantially uniform pressure exerted by said cleaning air flow. 13. A flow control member as claimed in any one of claims 1 to 12 wherein said flow redirection surface is less divergent than said divergent portion. 14. A method of cleaning filter cartridges, said cleaning being performed by means of cleaning air flowing into the filter cartridge in order to remove particles deposited on the outside of a filter cartridge, said method including the provision of uniform air pressure along a substantial area of the internal wall of the filter element being produced by means of a flow control member as claimed in any one of claims 1 to 13. 15. A method as claimed in claim 14 wherein the flow control member is positioned in the air flow entirely externally of the cartridge filter. O *o*