AU723824B2

AU723824B2 - Filtration system for removing solid particles

Info

Publication number: AU723824B2
Application number: AU61207/96A
Authority: AU
Inventors: Ulrich Franze
Original assignee: Individual
Current assignee: Individual
Priority date: 1995-06-19
Filing date: 1996-06-08
Publication date: 2000-09-07
Anticipated expiration: 2016-06-08
Also published as: DE19522133C2; EP0833685A1; CN1067290C; CN1188423A; AU6120796A; DE19522133A1; DE59604428D1; ATE189617T1; DE19680449D2; EP0833685B1; CA2224924A1; WO1997000111A1

Abstract

The invention concerns a filtration system for removing solid particles from liquids. In the filtration device, flexible sealing elements (3) are provided between the cover plate (1) and filter plate (2) to form a filtration chamber (4), as well as a filter unit (5) between the sealing elements and filter plate. A base plate is located beneath and at a distance from the filter plate. Flexible tubes are arranged between the filter plate and base plate (6) and are connected via a pressure medium to a pressure-generating device. The filter plate can move perpendicularly relative to the longitudinal axis of the cover plate (1).

Description

-s 0 VERIFIED TRANSLATION OF PCT %t 1/19 1,uOJ Description Filtration System for Removing Solid Particles The invention concerns a filtration system for removing solid particles from liquids using a cover plate and a filtration device adjoining the underside of the cover plate.

Mechanical removal processes and devices are familiar, these serving to separate what are mostly solid particles from liquids or suspensions as well as insoluble droplets of liquid from another liquid or emulsion aided by porous filter units flat in shape such as filter cloths or wire-fabric screen cloths or thick gravel-pack layers. The physical driving force as applied to filtration is the difference in pressure between the inlet and outlet ends of the filter brought about by the weight of the liquid column located above the filter. This force can, however, also be generated, or at least boosted, by presses on the inlet side or by applying vacuum on the outlet side (pressure or vacuum filtration).

Using automatic filter presses, for example, an attempt is made to shorten the process of filtration as well as setting-up times spent on replacing or separating the filter cake. In the case of the automatic chamber filter press, which is fitted with horizontal filter chambers located one on top of the other and an endless-belt type filter cloth, the filter plates can be moved up and down by means of an electro-mechanical opening and closing device. During this process the filter cake is separated sideways on the filter cloth. Replacement of a new unreeled filter cloth is effected by laterally mounted roller elements.

It has been shown on the conventional type of automatic vertical chamber filter press incorporating movable filter plates that evenness of ascent and descent on the filter plates, 2/19 controlled by laterally mounted lifting systems mounted on the side of the filter plates, is inadequate, thus resulting in leakages occurring on the filtration chambers acted upon by high pressure. Leakages are to be observed in particular on sealing elements used to seal off the sides of the filtration chambers. Leakages are incapable of being prevented even if equipping the filter chambers with flexible sealing elements as it becomes apparent that the more flexible a seal is, all the higher is the potential fragility of the material and thus all the shorter the service life of the sealing elements is bound to be. Guidance of the endless belttype filter cloth is likewise problematic and involves a complex roller system, in other words a large number of moving parts which are susceptible to disturbance.

The disadvantage of pressure filters designed with rigidly mounted rectangular ductlike filter chambers, whose ports, located opposite, can be closed off with tube-like seals for the filtration process, is that the filter cloth resting on the perforated base of the chamber develops a corrugated shape through constant use, this resulting in the solid matter seeping through. S-shaped distortion of the filter cloth is also inevitable and causes increased wear along the edges while the cloth is rendering service or leads to the formation of dead filtration zones.

Dead filtration zones are interpreted as being those areas which, despite their being covered over by the filter cloth, do not reveal any pores or inlet for the filtrate.

The disadvantage of chamber filter presses designed with horizontally movable filter plates is that the filter cloths are immobile for the purpose of improving cake discharge or for carrying out efficient cloth washing after each filtration process as a means of protection against blinding.

The term 'blinding' is used to describe clogging of the pores on the filter cloth.

3/19 The chamber filter press disclosed under DE 37 03 696 Al is provided with two end plates interposed by a set of filter plates around which a closed-loop filter cloth belt runs, this being tensioned by means of rollers. These rollers run inside the grooves of gibbets rigidly mounted to the plates. The chamber filter press also reveals a device providing contact pressure for the set of filter plates as well as manifolds linked to the feed and discharge lines of the matter due to be removed. The disadvantage observed here is that, although the load generated by the filter cloth belt while in motion is taken over by the plates, a heavy degree of strain is nevertheless exerted on tensioning elements.

US PS 50 94 760 merely describes a filtration system designed to run on intermittent lines incorporating several vertical filter plates rigidly mounted next to one another and whose interstices are acted upon by matter due to undergo filtration.

These interstices are rigidly mounted to two opposite sides and are capable of being locked at the top and bottom with tube-like seals for the process of filtration. In addition, a double-sided diaphragm is installed centrally between the filter plates and S: can be acted upon by a pressure medium for re-pressing the filter cake formed during the process of filtration. Here, however, due to the inadequate sealing of the filter media against the filter plates on the closed sides of the interstices, solid matter seepage occurs as well as premature blinding of the filter cloth due to single-sided washing.

:i From patent specification DD-A-135446 an apparatus is known employing a combination of several filtration devices connected in tandem, each consisting of a cover plate with a flexible perimeter sealing element, a movable filter plate arranged parallel to the same with a flexible perimeter sealing element and two filter cloths located between the plates forming a filter chamber whereby the filter cloths pass through the filtration devices in tandem forming an endless or closed loop and the filter plate is moved by means of a hydraulic cylinder perpendicularly relative to the longitudinal axis of the cover plate, thus opening or closing the filter chamber, also rendered possible is the process of pressing out the filter cake formed during the 4/19 filtration process. However, this device appears to the expert to be technically unrealisable for several reasons so that realisation thereof has hitherto been unknown.

The object of the invention presented here is not only to eliminate the abovementioned shortcomings revealed in the current state of the art, but also to create a universal filtration system capable of being constructed and operated at low cost owing to the simplicity of its design and thus having a favourable impact on industrial use for tasks encountered in the sector of environmental protection. In addition, facilities were needed for pressing out the possible formation of a compressible filter cake after filtration of the suspension or liquid.

Accordingly it appeared desirable to make provision for a filtration system which, under working conditions, would facilitate ascent and descent of evenly spaced filter plates while pressing the same against the cover plates. Another :'..advantage would be to cater for higher dehydration of a compressible filter cake by means of an additional pressing process making use of existing equipment so as to dispense with the necessity of employing costly diaphragms used on conventionaltype filtration systems for compressing filter cakes.

It was further deemed necessary to make provision for filtration to proceed on continuous lines, in which case replacement of filter cloths and/or separation of the filter cake might be rendered possible during filtration without disturbing, slowing down or even interrupting the filtration process. Here, it was regarded as being desirable to provide a filtration system that would be easy to handle while enabling a whole variety of different filtration processes to be performed without much conversion such as parallel- or series- connected filtration methods.

This task is solved by the main claim. The subordinate claims concern preferred design versions.

4a/19 The invention concerns a filtration system for removing solid particles from liquids or suspensions and is provided with a cover plate as well as filtration device located on the underside of the cover plate, characterised in that the said filtration device comprises flexible sealing elements and a filter plate, whereby the filter plate, which is aligned so as to run essentially parallel to the cover plate, is capable of being moved perpendicularly relative to the longitudinal axis of the cover plate, further that sealing elements are located between the cover plate and filter plate to form a filtration chamber and a filter unit is located between the sealing elements and the filter plate, further that a base plate is located underneath the filter plate at a distance from the filter plate, further that one or more flexible o o*o* 5119 lifting elements are located between the filter plate and base plate and are connected via as pressure medium to a pressure-generating device.

The filter plate is essentially aligned so as to run parallel to the cover plate owing to some slight deviations in its position likely to occur on account of the flexibility of the sealing elements. The sealing elements are also capable of acting as spacers between the filter plate and cover plate when the filter plate is pressed by the lifting elements against the sealing elements, e.g. while the filtration operation is in progress. Minor differences may occur in the formability or deformability of the sealing elements due to the nature of the material from which they made which, however, have had no noticeable effect on restricting the success of the invention.

There is also a likelihood of a slight difference occurring in the position of the filter plate on account of varying deformability of the lifting elements due to the resilience of the material, a circumstance which, however, does not deter from the outstanding success of the invention, especially as facilities are provided for carrying out appropriate adjustments to the position of the filter plate, e.g. by varying pressure using pressure-loadable sealing elements.

For example, preferred flexible lifting elements may assume the form of moulded cushions or air cushions usable as large- and/or small-area units. It is also possible to make use of tubes to serve as flexible lifting elements.

A type of tube capable of being used may be designed in such a way for example that, prior to pressure-loading, the circumference of the tube remains essentially unchanged in the t oss-sectional area in the relieved state as well as when pressure-loading takes place but 6/19 that the shape of the tube cross-sectional area differs before and during pressure-loading.

For example, a fabric-reinforced tube usable as a lifting element reveals a variable crosssectional shape in the relieved state but its circumference in the cross-sectional area remains essentially unchanged.

A flexible lifting element may assume the form of a hollow body with resilient walls made of flexible material which increases in diameter in the cross-sectional area when pressure is applied and which reduces its diameter in the absence of pressure due, for instance, to the inherent elasticity or internal stress of its material.

The flexible lifting elements are mounted between the filter plate and base plate in such a way that the flexible lifting elements due to their deformability when acted upon by pressure reduce the distance between the cover plate and filter plate when under pressure caused by the filter plate ascending perpendicularly to the longitudinal axis of the cover plate in the direction of the cover plate, i.e. upwards. When pressure is released, the diameter of the flexible lifting elements for example is reduced and the filter plate travels in the direction of the base plate, i.e. downwards. On account of the arrangement of the 0 flexible lifting elements, the filter plate remains essentially alighed parallel to the longitudinal axis of the cover plate during the ascending and descending motions.

It is observed as being an advantage when the diameter of the tubes undergoes change when pressure-loaded and the tubes reveal an approximately identical shape in the crosssectional area when acted upon by a defined pressure. Owing to the use of tubes, whose shape is capable of undergoing change when acted upon by pressure, the filtration system on which the invention is based caters for even distribution of forces over the filter plate so that ideal running up to the cover plate is rendered possible.

7119 In addition, it has been established that the use of flexible tubes enables the filter plates to be pressed with adequate evenness in the direction of the cover plate after filtration involving compressible filter cake, so much so that the filter cake is dehydrated to such an extent that adequate drying or dehydration of the filter cake is rendered possible without the necessity of employing additional costly diaphragms used on conventional-type filter systems.

In one version of the invention-related object, the tubes can be made to form a parallel, meander-shaped and/or circular arrangement. The preferable arrangement is to have the tubes arranged so as to be approximately parallel with one another. The arrangement of the tubes is dependent on the design of the filter plate, e.g. in the form of a round filter or rectangular-shaped filter. It proves an advantage if the tubes are linked to one another, for example using flexible connections, via a pressure medium. These flexible connections as well as the manifolds may assume same form, material and size as the tubes, again warranting homogeneous action of the contact-pressure forces produced by the tubes on the filter plate and by means of which the filter plate is pressed against the cover plate via the sealing elements.

020 In another version of the invention-related filtration system the tubes can be acted upon by the pressure-generating device via a pressure medium, preferably air, water and/or liquids containing oil. The use of pressure media is dependent on the designated application of the filtration system, although air or water (air in particular) will prove advisable, for example as a means of minimising corrosion on the pressure-generating device. Use can be made of machines to serve as a pressure-generating device that convey the energy fed to it from a drive unit to the gas and/or liquid, e.g. electric pumps and the like.

8/19 The design of the filter plates used on the invention-related filtration system is such that they provide free passage for the liquid, chiefly rendered possible by the filter plate being porous. The pores on the upper side of the filter plate are interlinked by ducts, at least to a partial extent, the liquid flowing through the ducting and/or via the pores located on the underside of the filter plate into a filtrate drain. For example, in the course of filtration, the liquid having been freed from solid particles passes through the filter unit via the pores located on the upper side of the filter plate and, by means of ducts, to the pores located on the underside. On the invention-related filtration system the filter plate can be, and is preferably designed with pores, in which case a number of the pores are interconnected via ducts, those ducts located on the outlet side being linked to a filtrate drain and those on the inlet side being connected up to the filtration chamber.

It is an advantage to load the tubes located on the underside of the filter plate with pressure in such a way that their diameter undergoes change, preferably as viewed from the cross-sectional angle. However, deformability as regards length has no disturbing effect.

Filter material capable of being used can assume the form of belt-type fabric filters of cloth or non-woven fabric as well as metal, natural, plastic- or glass-fibre, filtering paper, or filter diaphragms, e.g. from cellulose derivates, ceramic or plastic material. At the opposite ends of the filtration system or filtration device, roller elements can be fitted which, apart from guiding the filter unit, can if need be serve to wind it on or unreel it. The filter unit is guided on the filter plate of the invention-related filtration system in such a way that the entire area of the filter plate acts as a support to the filter unit, thus precluding the formation of dead zones which tend to restrict the filtration area on conventional systems.

Another advantage on the invention-related filtration system is that two or more A filtration devices can be combined, in which case the base plate on one of the filtration 9/19 devices is.designed as a cover plate with another filtration device then located on, or forming contact with the underside of that cover plate. A further advantage on the invention-related filtration system is that the filtrate drains are provided with a common outlet line, thus facilitating parallel connection of the filtration devices. On the other hand, it is also possible to link the filtrate drain on one of the filtration devices to the inlet line of the filtration chamber on another filtration device so as to facilitate series connection of the filtration devices. Connecting the filter devices up in series enables a higher stage of filtration to be carried out.

Resorting to parallel connection of the filtration devices provides the user with a continuous process by operating one filtration device, while on another such device the filter cake that has meanwhile accumulated can be separated laterally after shutting down the filter !i 1 plate and winding on or unreeling the filter medium.

Design Versions: Design versions are described in the following description with reference made to the drawings. The drawings are intended to provide a simplified portrayal in enlarged diagram ••form and thus lay no claim to being true to scale. They depict the following: oo oo 0 Fig. 1 Side view of the invention-related filtration system during the process of filtration and with the tubes being acted upon by compressed air.

10/19 X Fig. 2 Side view of the invention-related filtration system following completion of the filtration process and after the tubes have been evacuated.

Fig. 3 Top view focusing on the filter plate fitted with the filter unit.

The invention-related filtration system comprises a cover plate 1. Located underneath the cover plate 1 and parallel to it is a filter plate 2 (Fig. Flexible sealing elements 3 made of conventional rubber-like material can also be designed as flexible tubes so as to increase the lateral sealing efficiency on the filter chamber 4 of the invention-related filtration system. For example, tubes 7 and the sealing elements 3 designed as tubes can be linked to one another and acted upon simultaneously by air as a pressure medium.

Tubes 3 are arranged on the underside of the cover plate 1 in such a way that, when tubes 7 are acted upon by pressure, tubes 3 and the filter plate 2 seal off against the filter cloth 5. The cover plate 1 reveals feed lines capable of conveying the liquid due to be *0 filtrated to the filtration chamber 4.'Located on the underside of the filter plate 2 are flexible tubes 7, e.g. made of silicon and/or a rubber-like material and forming a parallel arrangement to one another. Pressure-loading here is effected by means of compressed air.

Tube 7 can be a fabric-reinforced type made of standard commercial plastic or material containing rubber and whose cross-sectional shape undergoes change when acted upon by pressure, but whose cross-sectional circumference remains essentially unchanged.

Use can also be made of tubing material not containing any fabric reinforcement made of standard commercial plastic or material containing rubber and on which the cross-sectional 11/19 circumference and cross-sectional shape both undergo change as pressure-loading of the tube varies.

As a result of pressure-loading, the filter plate 2 is made to move in the direction of the coverplate 1, thus sealing off the sides of filtration chamber 4 via the sealing elements 3 so as to prevent escape of the liquid that is under pressure and due to undergo filtration.

It is important that the filter plate 2 can be made to proceed in essentially parallel motion to the cover plate, perpendicularly to its longitudinal axis so as to warrant adequate sealing off of the filter chamber 4.

S 15 Located on the upper side of the filter plate 2 is a standard commercial filter cloth This filter cloth 5 is guided byroller elements 9 and wound or unwound on reels. The liquid due to be filtered is conveyed via feed lines through the cover plate 1 into the filter chamber i• 4, is pressed through the filter cloth 5 and then proceeds via the filtrate drains to a collecting basin. After a suitable filter cake has formed, the filtrate still present inside the filtration chamber 4 can be pressure-forced via the feed lines located in the cover plate 1 through the filter cake and into the filter plate 2. The filter cake can be dehydrated even further by •blowing air into the filtration chamber 4. On a compressible filter cake, it is also possible to 0c• apply a far higher pressure-load on tubes 7, thus reducing the distance between the cover plate 1 and the filter plate 2 by deforming the sealing elements 3, or even by relieving S 25 pressure on these sealing elements 3 in such a way that pressing out the filter cake can be carried out. The ducts of the filter plate 2 opening out via pores on the underside of the filter plate 2 lead to the filtrate drain or drains.

Tubes 7 are linked at one end by a manifold 12 (Fig. 3) which is connected up to a pump. The other end of tubes 7 are hermetically sealed off by means of dummy plugs 14.

12119 To effect disposal of the filter cake that has accumulated on the filter cloth 5, tubes 7 can be evacuated by pumping the pressure medium out of tubes 7. By opening a valve on the manifold 12 It is also possible to allow the pressure medium to escape from tubes 7 under inherent stress and the weight load of the filter plate 2 (Fig. 2).

After the filter plate 2 has been lowered, the filter cloth 5 can be made to travel sideways by means of roller elements 9 so as to remove the filter cake. In this case it is possible for the filter cloth 5 to be run back following separation of the filter cake or for it to remain on the roller elements 9. When running back the filter cloth 5, it can be cleaned by means of a pressure medium forced through a jet-nozzle unit mounted between the roller elements 9. While pressure is exerted on tubes 7, the filter plate 2 runs on guide rails arranged at the side of the filter plate 2, proceeding upwards in the direction of the cover plate 1 so that the longitudinal plane of the filter plate 2 is brought into parallel alignment with the longitudinal axis 11 of the cover plate 1 chiefly as a result of the evenly applied force coming from tubes 7, apart from revealing consistent spacing.

Besides it is possible, though not necessary or compulsory, for the sealing elements 3 to be linked to the same pressure-generating device used to load pressure on tubes 7.

Conversely, it is also possible for the sealing elements 3 to be coupled separately to a pressure-generating device.

Control equipment used to control the pressure-generating devices, the pumps used for supplying the filtration chamber 4 with filtration solution, etc. are not described in further detail here as these are conventional devices sufficiently familiar to the expert.

~L%\6lgter 'b19 d Thomas Ball ffentlich besteilt u. aligemein beeidigt a beirn Landgeiicht 131 Traunstein The fact that the invention-related filtration system can also be operated in such a way that the liquid due to be fed to it can be handled under pressure by the filter unit 5 or by applying vacuum on the outlet side of the filter plate 2 is regarded as an advantage.

The invention-related filtration system unites the optimum filtration properties of a laboratory-scale pressure suction filter with industrial requirements. The pressure-loaded rub,- system for lifting and lowering the filter plate applying virtually ideal distribution of S forces combines with the mobility of the filter medium for discharging the solid particles and subsequent cleaning of the filter cloth within a very short period of time so as to warrant extremely low downtime and thus a high degree of service time. The simplicity of the invention-related filtration system, e.g. by the use of easily replaceable tubes for the filterplate lifting system as well as easily exchangeable filter cloths for each filtration device cater for extremely high system availability.

By coupling up additional filtration devices, the filtration system is easily adapted to individual requirements where increase in capacity is called for. A computer control function incorporated in the filtration system facilitates optimum adaptation of the individual O cycles to given operating requirements. For the expert, these are factors serving to eliminate the familiar disadvantages associated with the current state of the art, while providing an ideal combination of the advantages brought about by the invention-related filtration system.

Claims

1. Filtration system for removing solid particles from liquids with a horizontal cover plate and a filtration device (10) located on the underside of the cover plate (1) whereby the filtration device (10) comprises flexible sealing elements and a filter plate which filter plate is aligned so as to be movable essentially parallel to the cover plate perpendicularly relative to the longitudinal axis (11) of the cover plate the sealing elements between the cover plate and the filter plate (2) forming a filtration chamber a filter unit located between the sealing elements and filter plate a base plate located underneath the filter plate and at a distance from the filter plate characterised in that there are several flexible lifting elements between the filter plate and base plate and connected via a pressure medium to a pressure-generating device.

2. Filtration system for removing solid particles from liquids according to claim 1, o characterised in that the flexible lifting elements are capable of being deformed when pressure-loaded, in such a way that the distance between the cover plate and the filter plate is rendered variable.

3. Filtration system for removing solid particles from liquids according to claim 1 or 2, .:66 characterised in that the flexible lifting elements assume the form of moulded cushions. u*

4. Filtration system for removing solid particles from liquids according to any of claims 1 to 3, characterised in that the flexible lifting elements assume the form of tubes.

I I' 15/19 Filtration system for removing solid particles from liquids according to claim 4, characterised in that loading of the tubes with a defined pressure results in the tubes revealing an approximately identical diameter in the cross-sectional area.

6. Filtration system for removing solid particles from liquids according to claim 4 or characterised in that the tubes are arranged approximately parallel to each other.

7. Filtration system for removing solid particles from liquids according to any, one of claims 4 to 6, characterised in that the tubes form a meander-shaped and/or circular arrangement. i

8. Filtration system for removing solid particles from liquids according to any one of claims 4 to 7, characterised in that the tubes are interconnected via a pressure medium. "20

9. Filtration system for removing solid particles from liquids according to any one of claims 4 to 8, characterised in that the tubes are acted upon by a pressure- generating device via a pressure medium. 0 0 0 0

10. Filtration system for removing solid particles from liquids according to any one of claims 1 to 9, characterised in that the sealing elements are designed in the form of flexible tubes.

11. Filtration system for removing solid particles from liquids according to claim characterised in that the sealing elements are connected via a pressure medium to a z RA7 pressure-generating device. 16/19

12. Filtration system for removing solid particles from liquids according to any one of claims 1 to 11, characterised in that the filtration system reveals two or more filtration devices

13. Filtration system for removing solid particles from liquids according to claim 12, characterised in that the base plate of one filtration device (10) is designed as a cover plate in such a way that another filtration device (10) is located on the underside of that cover plate

14. Filtration system for removing solid particles from liquids according to claim 12 or 15 13, characterised in that the filtrate drains of the filtration devices (10) open out into a common outlet line. *9

15. Filtration system for removing solid particles from liquids according to claim 12 or 13, characterised in that the filtrate drain on one of the filtration devices (10) is connected to the inlet lines of the filtration chamber on the other filtration device S** o* 9

16. Filtration system for removing solid particles from liquids substantially as herein before described with reference to the drawings. Ulrich Franze By his Patent Attorney Allen J. Evans of EVANS ROSE RCj A Dated: 22 April, 1999 EDITORIAL NOTE NO.61207/96 This specification does not contain pages 17/19 to 19/19.