EP1622701A1

EP1622701A1 - Membrane plate and filter element

Info

Publication number: EP1622701A1
Application number: EP04731568A
Authority: EP
Inventors: Eberhard Harms; Mark Grigo
Original assignee: Utisol Technologies AG
Current assignee: Utisol Technologies AG
Priority date: 2003-05-09
Filing date: 2004-05-07
Publication date: 2006-02-08
Also published as: US7678273B2; CN1845782A; EP1475142A1; US20070023348A1; WO2004098754A1; CA2525182A1

Abstract

The invention relates to a filter unit (10) comprising membrane plates (1) which are placed parallel to one another while being joined in a liquid-tight manner at least in areas (4) around connecting elements (2) for withdrawing permeate, i.e. filtered liquid. After placing two membrane plates one atop the other, these membrane plates are, due to their shape, provided for producing a sealing by welding, whereby forming a liquid-tight connection. This prevents the unfiltered liquid from flowing through between the membrane plates (1) and the permeate from becoming contaminated in a volume around the connecting elements. In a preferred embodiment of the invention, a connection that, for the time being, is positive is provided from which a connection with material fit is formed by welding. A hollow profile section (11) can be mounted via a number of connecting elements (2) and areas (4) located therebetween and can be closed at the ends thereof. Said hollow profile section surrounds discharge openings of the connecting elements (2) and the areas located therebetween in a liquid-tight manner, preferably with material fit. This results in the formation of a permeate collecting channel (11) out of which the permeate can be drawn by suction via a permeate withdrawal point (13).

Description

MEMBRANE PLATE AND FILTER UNIT

The invention relates to the field of filter technology, in particular to a membrane plate and a filter unit according to the preamble of patent claims 1 and 7, and to a method for producing a filter unit according to the preamble of patent claim 15.

STATE OF THE ART

Filter units, which are typically equipped with membrane filters, are used in filter devices, in particular in treatment plants for waste water or drinking water. A large number of membrane filters are arranged in a rectangular suspension and are operated immersed in the liquid to be filtered. Each membrane filter has a support plate with two filter membranes. Permeate, ie filtered liquid, collects in cavities or lines within the membrane filter. The individual membrane filters are each connected via individual connections, for example pipes or hoses, to a permeate collecting line, which sucks the permeate out of the membrane filters. When the system is set up, the membrane filters are installed individually and connected to the permeate manifold. In the event of a revision or cleaning, they are detached individually. This procedure is cumbersome and time-consuming and increases the manufacturing and assembly costs of the system. EP-A-1 016 449 shows how a plurality of filter bags arranged in parallel are inserted into a basin with liquid casting resin. After the casting resin has hardened, perforations to the filter pockets are milled into the casting resin. According to a specific embodiment, the filter bags have plug-in projections and cutouts along two edges. This means that they can be connected to form a package by plugging them together. The manufacturing process is also complex here.

PRESENTATION OF THE INVENTION

It is therefore an object of the invention to provide a membrane plate and a filter unit of the type mentioned at the outset which overcome disadvantages of the prior art and in particular allow a simple and inexpensive construction of a filter unit.

This object is achieved by a membrane plate and a filter unit with the features of patent claims 1 and 7, and a method for producing a filter unit with the features of patent claim 15.

In the filter unit according to the invention, therefore, at least two membrane plates according to the invention are placed parallel to one another and are connected to one another in a liquid-tight manner at least in areas around connection elements for discharging permeate. Due to their shape, the membrane plates are intended for manufacture, after two membrane plates have been placed on top of one another, such a liquid-tight connection or sealing by welding. No further connecting or sealing bodies are therefore required between or next to the membrane plates. This prevents unfiltered liquid from flowing between the membrane plates and contaminating the permeate in a volume around the connection elements. There is preferably only a seal between the membrane plates in the area of the connection elements. A connection element can also consist of several openings in an edge. A connection element or the multiple openings, however, only occupy a comparatively small area of a longitudinal edge, for example less than a fifth or as a tenth of the longitudinal edge. This increases the effort required to produce the seal and the reliability of the seal.

This seal is achieved, for example, by a form-fitting and thereby liquid-tight connection between the at least two membrane plates, for example by a watertight plug or snap connection of a sealing profile. In another preferred embodiment of the invention, there is a positive connection for the time being, from which a material connection is formed. Depending on the material of the membrane plates, this is done by gluing, welding or soldering, after which the membrane plates are generally no longer detachably connected without damage. The material is preferably a thermoplastic, and the membrane plates are welded or fused together in the area between the connection elements.

A hollow profile, which is closed at its ends, can be attached over several connecting elements and areas in between. This encloses outlet openings of the connection elements and the areas lying between them in a liquid-tight, preferably cohesive, manner. This creates a permeate collection channel, from which the permeate can be drawn off via a permeate discharge. The connection points mentioned between membrane plates and between membrane plates and permeate collection channel are preferably formed by flat surfaces, which allows simple manufacture. Joints between individual membrane plates can also be formed by tongue-and-groove connections, which snap in, for example, non-positively, wedge or can be welded together. In order to increase a distance between membrane plates, depending on the medium to be filtered and the type of impurities, spacer elements or spacers can be inserted at individual points, for example between the longitudinal edges of the membrane plates. These are connected like the membrane plates, for example plugged and / or welded.

In summary, a complete, ready-to-use filter module can be produced from a number of identical membrane plates according to the invention simply by welding the welding areas for sealing, welding the permeate collecting channel and a few welding beads to connect the membrane plates. The spacing elements make it easy to adapt to different liquid properties.

The very simple and inexpensive manufacture of a filter unit eliminates the need for extensive revisions, and a filter unit as a whole can simply be replaced. The filter unit according to the invention is particularly suitable for domestic sewage treatment plants and water filtration due to the inexpensive and compact design.

In the present application, the term "water" or "dirty water" denotes waste water or drinking water to be treated. However, the invention is also applicable to filter units for other liquids. Further preferred embodiments emerge from the dependent patent claims. Features of the method claims can be combined with the device claims and vice versa.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter of the invention is explained in more detail below on the basis of preferred exemplary embodiments which are illustrated in the accompanying drawings. Show it:

Figures 1 to 3 different views of a filter unit according to the invention; Figure 4 schematically shows a perspective view of part of a

Filter unit with several membrane plates; and FIGS. 5 to 7 schematically show different views of one another

Membrane plates in the area of permeate outflow shafts. The reference symbols used in the drawings and their meaning are summarized in the list of reference symbols. In principle, the same parts are provided with the same reference symbols in the figures.

WAYS OF CARRYING OUT THE INVENTION

Figure 1 shows a side view, Figure 2 shows a plan view and Figure 3 shows a cross section through a filter unit 10 according to the invention. The position shown corresponds to an operating position of the filter unit 10, in which it is operated immersed in a liquid to be filtered and through which the liquid flows from bottom to top. A corresponding direction of flow is indicated by arrows. The filter unit 10 is mainly formed by a plurality of membrane plates 1 placed parallel and covering one another or congruently against one another. Such a stack of membrane plates 1 can pass through on two sides Cover plates 15 must be completed. The cover plates 15 have spacing knobs 18 for spacing further filter units 10. In a region of a first longitudinal edge 6a and a second longitudinal edge 6b, adjacent, parallel arranged membrane plates 1 are each positively connected to one another, for example by means of tongue-and-groove connections 16 arranged on the longitudinal edges 6a, 6b. This provides a positive connection between the at least two Membrane plates (1) can be formed in the area between the connection elements (2). These connections do not necessarily have to be liquid-tight. It is sufficient if the liquid flowing upwards and possibly mixed with purging air does not essentially escape laterally through the longitudinal edges 6a, 6b. In the orientation of the flow described, the membrane plates 1 are not connected to one another along the shorter edges.

The membrane plates 1 are preferably formed in one piece from a thermoplastic material, for example from polypropylene, ABS, etc. At one or more points, the membrane plates 1 are further welded to one another by welding beads 14 running perpendicular to the first longitudinal edges 6a and the second longitudinal edges 6b, respectively.

Here and below, integral connections are described which are formed by welding thermoplastic material. However, it is also possible to make the connections by gluing or, in individual cases, by liquid-tight plug connections. If other materials are used for the membrane plates 1, connections can also be soldered.

In a region of the first longitudinal edge 6a, each membrane plate 1 has a permeate outflow shaft 2. This leads from an inside of the membrane plate 1 to an outlet opening located in a surface of the first longitudinal edge 6a. The outlet openings of all membrane plates 1 are through a permeate collecting channel 11 enclosed with a line to the permeate vent 13. The permeate collection channel 11 and the membrane plates 1 are welded along a welding edge of the permeate collection channel 12. In order to seal the permeate collecting channel 11 with respect to the liquid "flowing in the filter unit 10, regions of the membrane plates 1 between the permeate outflow shafts 2 or their outlet openings are also welded to one another.

The permeate collection channel 11 can have a second connection piece (not shown), which is opposite the permeate discharge 13 and can be connected to the inside of the permeate collection channel 11 via a break-through point. As a result, two filter units 10 can be placed on top of one another and operated connected to one another by a hose.

For large filter capacities, the membrane plates 1 preferably each have a second permeate outflow shaft, and the filter unit 10 has a second permeate collection channel (not shown). This is preferably arranged at an end opposite the permeate collecting channel 11 on the same wall of the filter unit 10, for example at about the height of the welding bead 14 shown in FIG. 1. The permeate collecting channel 11 then preferably has a second connection opposite the permeate discharge 13, which is connected by a Hose or a piece of pipe with a permeate discharge of the second permeate collection channel is connectable.

FIG. 4 schematically shows a perspective view of part of a filter unit with several membrane plates in the area of the permeate outflow shafts 2. A membrane plate 1 has two filter membranes 7, which are arranged on both sides of a support plate 8. A permeate outflow shaft 2 of a membrane plate 1 leads from a volume located between the filter membranes 7 to the first longitudinal edge 6a of the membrane plate 1. The shaft is preferably designed as a rectangular channel essentially perpendicular to the first longitudinal edge 6a. The Permeate discharge shaft 5 can also be round or oval in shape. A region around the outlet opening of the permeate outflow shaft 2 is preferably flat. This area forms 2 welding areas for sealing 4 on the two longitudinal edges of the permeate outflow shaft and 2 welding areas for the permeate collecting channel 5 on the short edges of the permeate outflow shaft.

When producing the filter unit 10, when welding several membrane plates 1 together, a welding area for sealing 4 a first membrane plate 1 comes to lie against a welding area for sealing 4 a second membrane plate 1. These welding areas of all membrane plates 1 are fused together in pairs in a single operation by mirror welding. For this purpose, the welding mirror used has a length that corresponds to a width of the filter unit 10 and a height that corresponds to a height of the outlet openings. As a result, beads of fused material form between the permeate outflow shafts 2, which form a material-tight and liquid-tight connection with respect to an area or volume of unfiltered liquid lying between the membrane plates 1.

In a further operation, the permeate collection channel 11 is welded along the welding edge of the permeate collection channel 12 to welding areas for the permeate collection channel 5 of the membrane plates 1. For this purpose, the flat and welded areas for the permeate collecting channel 5, which are placed against one another, form an essentially flat surface, so that the welding edge of the permeate collecting channel 12 can be made straight. The welding areas for permeate collection channel 5 do not necessarily have to be flat. For example, they can also be corrugated, in which case the welding edge of the permeate collection channel 12 must also be corrugated accordingly. The flat shape is preferred for reasons of ease of manufacture. Preferably, in order to achieve a completely tight connection between the membrane plates 1 in the area of the welding area for the permeate collecting channel 5, these areas are welded together in a separate operation before the permeate collecting channel 11 is welded on. The welding areas for the permeate collecting channel 5 are pressed together flat in the meltable state with a pressure stamp. The pressure stamp also presses on the welding areas of the cover plates 15, which bear against the welding areas for sealing 4 of the outer membrane plates 1. The shape of the pressure stamp thus corresponds approximately to the shape of the welding edge of the permeate collecting channel 12.

FIG. 4 shows the flat area 4, 5 around the outlet openings as raised compared to the rest of the area of the first longitudinal edge 6a. The increase in these welding areas 4, 5 is, for example, 1 to 2 mm. However, it cannot be raised, but there must be sufficient material between the welds and the tongue-and-groove connection to ensure a clean weld. FIG. 4 also shows elevations for the formation of a welding bead 14. The welding bead is produced by heating the plastic and pressing on an elongated stamp.

FIGS. 5 to 7 schematically show views of membrane plates 1 placed against one another in the area of the permeate outflow shafts 2 in various embodiments of the invention. In contrast to FIG. 4, the welding areas 4, 5 are not shown raised or exaggerated. FIG. 5 corresponds to an arrangement as in FIG. 4. A vertical extension of the connection areas, in which the welding areas for sealing 4 are welded to one another during mirror welding, is designated by reference number 17. In FIG. 6, a greater distance between the membrane plates 1 is achieved by first spacers 9a inserted between the membrane plates 1 in the region of the first longitudinal edges 6a. Analogously, second spacers 9b, not shown, are inserted between the membrane plates 1 in the region of the second longitudinal edges 6b. FIG. 7 shows how an alternative embodiment of the invention can achieve a greater distance between membrane plates 1 by widening the longitudinal edges 6a, 6b.

If a cover plate 15 is dispensed with, the welding edge of the permeate collection channel 12 can be provided with a lip protruding in the direction of the membrane plate 1 in order to improve the mechanical stability and the quality of the welded connection or fused seam, which lip respectively when placed on a stack of membrane plates 1 includes an edge of the first longitudinal edge 6a of the two outer membrane plates 1.

Exemplary dimensions for the size of a membrane plate 1 and thus also the filter unit 10 are a length of 30 to 60 cm and a width of 5 to 20 cm. A thickness of the filter unit 10 can be 20 to 50 cm or more and have ten, twenty or more membrane plates 1. Accordingly, filter areas of several square meters are realized. With a thickness of a membrane plate 1 of 5 mm, an outlet opening is approximately 2 mm wide and 15 to 20 mm high. A thickness of a web of a welding area for sealing 4 is then approximately 1 to 1.5 mm. the welding area for the permeate collecting channel 5 extends from the outlet opening by half to over one centimeter along the first longitudinal edge 6a. The stated dimensions are to be understood as examples; within physically sensible limits, the mass can essentially be varied as desired without departing from the scope of the invention. LIST OF REFERENCE NUMBERS

1 membrane plate

2 permeate discharge shaft

3 shaft edge

4 welding area for sealing

5 welding area for permeate collection channel 6a first longitudinal edge

6b second longitudinal edge

7 filter membrane

8 support plate

9a first spacer

9b second spacer

10 filter unit

11 permeate collection channel

12 welding edge of the permeate collection channel

13 permeate deduction

14 Survey to form a welding bead

15 cover plate

16 tongue and groove connection

17 Area for mirror welding for sealing

18 spacer knobs

Claims

1. membrane plate (1) for supporting filter membranes (7), in particular for a water filter of a water treatment or wastewater treatment plant, comprising a connecting element (2) for removing permeate collected in the membrane plate (1), characterized in that at least two identically shaped Membrane plates (1) can be arranged parallel to one another, and are provided by welding to produce a liquid-tight connection of the membrane plates (1) in an area between the connection elements (2) of the at least two membrane plates (1) arranged in this way.

2. Membrane plate (1) according to claim 1, wherein the connecting element (2) is a shaft formed in a first longitudinal edge (6a) of the membrane plate (1), and wherein a border of the shaft (2) when emerging from the first longitudinal edge (6a ) is formed by a flat surface.

3. Membrane plate (1) according to claim 2, wherein first areas of the border of the shaft (2) form connecting areas for sealing (4) between adjacent membrane plates (1) or between membrane plates and spacers (9a), and second areas of the border connecting areas (5 ) for connection by welding with a permeate collection channel (11).

4. Membrane plate (1) according to claim 3, wherein the first and second regions of the border (4, 5) are raised relative to a remaining region of the first longitudinal edge (6a).

5. membrane plate (1) according to any one of claims 1 to 4, wherein a connecting element (2) a comparatively small area of an edge (6) through which the connecting element (2) leads claimed.

6. membrane plate (1) according to one of claims 1 to 5, comprising a further connection element, which is configured analogously to the connection element (2) and is designed for connection by welding to a second permeate collection channel.

7. Filter unit (10), in particular for a water filter of a water treatment or wastewater treatment plant, characterized in that it has a plurality of firmly connected membrane plates according to one of claims 1 to 6.

8. Filter unit (10) according to claim 7, in which at least two membrane plates

(I) are arranged parallel to each other and there is a liquid-tight connection at least in areas between the connection elements (2) of the at least two membrane plates (1).

9. Filter unit (10) according to claim 8, in which the membrane plates (1) are made of thermoplastic material and the liquid-tight connection is a welded connection.

10. Filter unit (10) according to claim 8 or 9, in which a permeate collection channel

(II) encloses the connection elements (2) of the at least two membrane plates (1) in a liquid-tight manner.

11. Filter unit (10) according to one of claims 8 to 10 as a function of claim 6, comprising a further permeate collection channel, which encloses further connection elements of the at least two membrane plates (1) in a liquid-tight manner.

12. Filter unit (10) according to claim 10 or 11, wherein the permeate collection channel (11) or the further permeate collection channel one at two ends is closed hollow profile and has a permeate discharge (13) for deriving permeate.

13. Filter unit (10) according to one of claims 7 to 12, wherein at least one spacer (9a) is arranged between a first and a second membrane plate (1) and the area between the connection elements (2) of the at least two membrane plates (1) comprises first spacer (9a) and a liquid-tight connection between the first membrane plate (1) and the first spacer (9a) and a liquid-tight connection between the first spacer (9a) and the second membrane plate (1).

14. Filter unit (10) according to one of claims 7 to 13, wherein the at least two membrane plates (1) and optional spacers (9a, 9b) on an edge (6a, 6b) correspondingly arranged elevations (14) to form at least one welding bead for Have the at least two membrane plates (1) welded.

15. A method for producing a filter unit according to one of claims 7 to 14, comprising the following steps:

Laying together at least two membrane plates (1) provided with filter membranes (7) according to one of Claims 1 to 7, with spacers (9a, 9b) optionally being placed between the membrane plates (1); Welding of welding areas between the connection elements (2) of the membrane plates (1) for sealing (4).

16. A method for producing a filter unit according to claim 15, with the following further step:

Welding a connection area (5) surrounding a group of connection elements (2) with a welding edge of a permeate collecting channel (12).

17. A method for producing a filter unit according to claim 16, wherein prior to the welding with a welding edge of a permeate collecting channel (12), the connection area (5) surrounding the group of connection elements (2) is welded by pressing a pressure stamp.

18. A method for producing a filter unit according to one of claims 15 to 17, wherein the membrane plates (1) placed against one another and optionally the spacers (9a, 9b) are connected to one another by welding at further points (14).

19. The method for producing a filter unit according to claim 18, wherein the further points (14) are welded by heating and pressing on an elongated die.