MEMBRANE FILTER AND METHOD FOR PRODUCING A MEMBRANE FILTER

Description

[0001] The invention relates firstly to a membrane filter for submerged operation for filtering a liquid with membrane elements which are arranged horizontally next to one another and each have the following features: Membranes arranged in a vertical longitudinal direction for filtering a liquid permeate from the liquid, a header arranged at a header height with a permeate collection chamber to which the membranes are connected on the permeate side, and a permeate outlet for discharging the permeate in a horizontal outlet direction from the permeate collection chamber, and a tube which connects to the top of the respective header and laterally encloses the membranes of the respective membrane element, wherein the permeate outlets are connected to a horizontally extending, common permeate collector that removes the permeate from the membrane filter. The invention further relates to a method for producing such a membrane filter.

[0002] Such a membrane filter and such a process are known from DE 10 2019 115265 A1. The tube has the advantage that the gas introduced for flushing purposes cannot leave the membrane area laterally and can flow upwards alongside the membranes unused.

[0003] In the background of the invention, DE 10 2019 129074 B3 discloses a similar membrane filter, but without the actual permeate collection.

[0004] The membrane filter known from US Pat. No. 7,037,426 B2 has a permeate collector located above the membrane elements. From the permeate outlets of the headers attached to the bottom of the membrane elements, the permeate is initially led upwards through pipes parallel to the membranes into the permeate collector located above the liquid surface. The permeate outlets are connected to the pipes only by a form-fitting connection.

[0005] In further background of the invention, US 2004 / 0188339 A1 discloses a membrane filter in which the permeate is discharged vertically from the permeate collection space.

[0006] The membrane filters of WO 2004 / 078326 A2, US 2004 / 206683 A1 and US 2019 / 247772 A1 do not have a tube laterally enclosing the membranes and the permeate collector is not located at header height next to the headers. Task

[0007] The invention is based on the object of simplifying the production of the membrane filter. Solution

[0008] Based on the known membrane filter, the invention proposes that the permeate collector is arranged at the header height next to the headers.

[0009] Preferably, a membrane filter according to the invention has projections and recesses on the headers and on the permeate collector, wherein the projections protrude into the recesses and fix the headers to the permeate collector in the longitudinal direction. It is within the scope of the invention that the header has the projections and the permeate collector has the recesses, and conversely, that the permeate collector has the projections and the permeate collector has the recesses.

[0010] The longitudinal fixation of the header to the permeate collector is important, for example, for the operation of the membrane filter in membrane bioreactors (MBR). Here, a gas, usually air, is blown between the membranes from below to flush the membranes. This flushing air is often introduced in a pulsating manner, which leads to alternating vertical loads in the membrane element. The vertical fixation of the header to the permeate collector in the longitudinal direction therefore makes a decisive long-term contribution to maintaining the sealing effect in the connections of the permeate outlets to the permeate collector.

[0011] It is within the scope of the membrane filter according to the invention that the membrane elements can be equipped with various types of membranes, such as hollow fiber membranes, plate membranes, pillow membranes, or hollow fiber membranes connected to form curtains. The membranes themselves preferably belong to the range of ultrafiltration or microfiltration membranes with pore sizes between 0.02 and 1.0 µm. However, other membranes from the field of nanofiltration or low-pressure reverse osmosis can also be used.

[0012] Preferably, a membrane filter according to the invention has bars on the permeate collector that extend in the outlet direction, wherein two of the bars each hold one of the headers horizontally transversely to the outlet direction on the permeate collector.

[0013] Preferably, such a membrane filter according to the invention has snap-in connections between the beams and the headers, which fix the headers to the permeate collector in the outlet direction. This allows the membrane elements to be mounted in the membrane filter without the use of tools.

[0014] It is within the scope of the invention that the permeate collector is assembled from individual elements, for example, injection-molded parts. The injection-molded parts are glued together, for example. The beams can also be inserted as individual parts with a form-fitting fit or additionally glued together.

[0015] Preferably, the membranes are hollow-fiber membranes that are individually sealed at the top. When using hollow-fiber membranes, these can be configured in double-header or single-header systems. Both are expressly within the scope of the invention for the design of the membrane elements. In double-header systems, the hollow-fiber membranes are secured at the top and bottom in headers. In the single-header design, the membranes float individually sealed at the top in the liquid to be filtered, while they are only secured at the bottom in a foot element. This has the advantage, particularly when the membrane filters are used in municipal membrane bioreactors, that hair and fibrous compounds contained in the sludge to be filtered can be freely stripped upwards from the membranes and flushed out of the membrane element. This reduces the pretreatment effort for the incoming wastewater.

[0016] Preferably, in a membrane filter according to the invention, additional headers are connected to an additional permeate collector on the permeate side at at least one additional header height above the header height. This can be the case, for example, if the membrane elements are double-header systems in which the membranes are fixed at the top and bottom in a header. In this case, the lower headers are each connected to the permeate collector, and the upper header, as an additional header, is connected to the additional permeate collector above the header height.

[0017] However, it is also within the scope of the invention that the additional headers connected to another permeate collector above the header height belong to additional membrane elements mounted above the membrane element connected to the permeate collector. This is the case in so-called double-decker membrane filters, in which two or more membrane elements are installed one above the other in the filter. The membrane elements mounted on one level are each connected to a common permeate collector on that level.

[0018] Preferably, a membrane filter according to the invention comprises geyser elements mounted at the bottom of the headers, each with a downwardly open gas collection chamber for collecting an incoming gas and an outlet device for releasing the gas in pulses into the respective header. The pulsed release of the gas leads to a significantly more effective flushing effect of the membranes and is also comparatively energy-efficient.

[0019] Based on the known method, the invention proposes that the permeate collector be arranged at the header height next to the headers. The method according to the invention, with which a membrane filter according to the invention can be produced, is similarly characterized by the aforementioned advantages.

[0020] In a method according to the invention, the headers are preferably connected to the permeate collector only by means of a form-fitting connection. This, in turn, has the advantage that no tools are required for the assembly of the membrane elements in the membrane filter.

[0021] Preferably, in a method according to the invention, projections and recesses on the headers and on the permeate collector are inserted horizontally into one another. The projections inserted into the recesses block displacement of the respective headers against the permeate collector and fix them vertically to the permeate collector. This absorbs vertical forces in the membrane element, and the connection between the membrane element and the permeate collector via the permeate outlets is protected from mechanical damage.

[0022] Here too, it is within the scope of the invention that either projections on the headers are inserted into recesses of the permeate collector or, conversely, recesses of the header are inserted into projections on the permeate collector.

[0023] In a method according to the invention, the headers are preferably inserted in the outlet direction between two beams on the permeate collector in such a way that the beams fix the respective header horizontally, transversely to the longitudinal direction. Preferably, the projections are simultaneously guided into the recesses. The beams support the insertion of the permeate outlet of the membrane element into openings of the permeate collector.

[0024] Preferably, in such a method according to the invention, snap-in connections between the beams and the headers engage during insertion, securing the respective header in the longitudinal direction. This ensures that the nested connection of projections and recesses cannot come loose during operation, thus ensuring a secure connection between the membrane elements and the permeate collector.

[0025] Preferably, in a method according to the invention, the membrane elements are first suspended from the top of a frame using an upper mount, and then the respective header is connected to the permeate collector. This brings the height of the permeate outlet close to the corresponding opening in the permeate collector during assembly of the membrane element in the membrane filter, facilitating the insertion of the projections into the recesses.

[0026] Preferably, in a method according to the invention, geyser elements are mounted below the membrane elements below the headers between each pair of the spars on the permeate collector, each with a downwardly open gas collection chamber for collecting an incoming gas and an outlet device for releasing the gas in pulses into the respective header. This significantly improves the flushing effect of the introduced gas, for example, in membrane bioreactors. Examples of implementation

[0027] The invention is explained below using exemplary embodiments. Fig. 1a shows a first membrane filter according to the invention, Fig. 1b shows a membrane element of the first membrane filter, Fig. 1c shows a detailed section of the membrane element and Fig. 1d shows three steps in the production of the first membrane filter, Fig. 2a shows a second membrane filter according to the invention, Fig. 2b shows a membrane element of the second membrane filter and Fig. 2c shows a section through the membrane element, Fig. 3a shows a third membrane filter according to the invention, Fig. 3b shows a permeate collector of the third membrane filter, Fig. 4 shows a fourth membrane filter according to the invention, Fig. 5a shows a fifth membrane filter according to the invention and Fig. 5b shows a membrane element of the fifth membrane filter and Fig. 6 shows a sixth membrane filter according to the invention.

[0028] The figures are simplified representations, in particular not to scale, to explain the principle underlying the invention.

[0029] The Figure 1aThe first membrane filter 1 according to the invention for filtering a liquid shown has membrane elements 2 arranged horizontally next to one another and a common permeate collector 3 to which the membrane elements 2 are connected.

[0030] The permeate collector 3 of the first membrane filter 1, which is cuboid in its basic form, has a longitudinally continuous oval channel 5 in the header height 4, as well as circular permeate openings 6 in the channel 5, two bars 7 for each header 12 and a recess 8. The bars 7 each have a groove 9.

[0031] The Figure 1b The membrane element 2 of the first membrane filter 1 shown has individually closed membranes 10 at the top, a tube 11 surrounding them at the sides and a header 12 at the bottom.

[0032] The Figure 1cThe header 12 shown in section comprises a substantially tubular housing 13 and, on the housing 13 at the front of the membrane element 2, a permeate outlet 14 for discharging the permeate horizontally in an outlet direction 15 into the permeate collector 3 and a projection 16, as well as a cam 17 on each side that is beveled towards the front. Inside the housing 13, the header 12 comprises a membrane block 18 in which the membranes 10 are fixed.

[0033] In the membrane block 18, the membranes 10 penetrate a sealing layer 19 and open into a permeate collection chamber 20. The pipe-shaped permeate outlet 14 from the permeate collection chamber has a molded collar 21 and a sealing ring 22 made of a polymer. Below the membrane block 18, the header 12 has an inflow opening 23 through which the liquid and a gas (not shown) for flushing the membranes 10 can be directed into the interior of the membrane element 2. Figure 1dillustrates a partial step in the assembly of a membrane element 2 during the production of the first membrane filter 1 in three steps: The bars 7 center the header 12 on the permeate collector 3 in such a way that the permeate outlet 14 is guided into the permeate opening 6 and the projection 16 into the recess 8. In the final position, the sealing ring seals the permeate outlet 14 against the permeate opening 6, the projection 16 lies positively in the recess 8 and the two cams 17 of the header 12 engage in the grooves 9 of the bars 7. The header 12 and the permeate collector 3 are injection-molded from ABS and are uniformly colored green (Pantone 2287C).

[0034] Figure 2ashows a second membrane filter 24 according to the invention. The second membrane filter 24 essentially corresponds to the first membrane filter 1, but has a further permeate collector 27 mounted in a frame (not shown) above the first permeate collector 25 at a further header height 26.

[0035] Figure 2b shows a view of a membrane element 28 of the second membrane filter 24 according to the invention and Figure 2c a section through the membrane element 28.

[0036] In contrast to the first membrane filter 1 according to the invention, the membranes 29 are not closed at the top, but open into a further header 30. The housing 31 of the further header 30 with permeate outlet 32 ​​and projection 33 at the front and with the laterally attached cams 34 corresponds to that of the first header 35 attached at the bottom.

[0037] The membrane block 36, in which the membranes 29 are fixed in the further header 30, is arranged in a mirror image of that of the first header 35. The permeate outlets 32 of the further headers 30 are connected to the further permeate collector 27 through permeate openings (not shown). Furthermore, in the membrane element 28 of the second membrane filter 24, the membranes 29 are not surrounded by a tube.

[0038] The Figure 3a The third membrane filter 37 according to the invention shown again essentially corresponds to the first membrane filter 1. Deviating from this, the third membrane filter 37 has a geyser element 39 at the bottom of each of the headers 38. The geyser element 39 has a tubular housing 40 with a rectangular cross-section, a downwardly open gas collection chamber 41, and an outlet device 42 for the pulsed discharge of a gas (not shown) from the gas collection chamber 41.

[0039] The outlet device 42 of the geyser element 39 has a gas lift channel 43 for the downward outflow of the gas from the gas collection chamber 41 and a deflection region 44 at the bottom of the gas lift channel 43 for deflecting the outflowing gas upward. An outlet channel 45 adjoins the deflection region 44 at the top for discharging the gas upward from the geyser element 39 into the header 38 of the membrane element 46.

[0040] When the gas collection chamber 41 is filled with gas, a liquid level (not shown) in the gas collection chamber 41 sinks until it falls below the outflow channel 45. The gas then flows from the top through the gas lift channel 43 downwards into the deflection area 44, is deflected upwards there, and then flows out of the gas collection chamber 41 through the outflow channel 45 at the top of the geyser element 39 until the gas collection chamber 41 and the outlet device 42 are again flooded with liquid from below. The gas filling process then begins again. Thus, the continuous gas inflow at the bottom into the geyser element 39 creates a pulsating gas outflow at the top from the geyser element 39 into the membrane element.

[0041] The Holme 47 of the Figure 3bThe permeate collector 48 shown in FIG. 1 is divided in the outlet direction 49, unlike the first membrane filter 1, and has a groove 52 in each part 50, 51. The upper parts 50 hold the headers 38, and the lower parts 50 hold the geyser elements 39.

[0042] Figure 4shows a fourth membrane filter 53 according to the invention. The fourth membrane filter 53 essentially corresponds to the third membrane filter 37. Unlike the fourth membrane filter 53, it has further membrane elements 55 above the first membrane elements 54. The further membrane elements 55 correspond to the first membrane elements 54. The further membrane elements 55 are connected to a further permeate collector 59 at a further header height 56 ​​above a header height 57 by means of further headers 58. Geyser elements 61 are connected below headers 60 located at header height 57 for the pulsed introduction of a gas (not shown) from below into the membrane elements 54.

[0043] Figure 5a shows a fifth membrane filter 63 according to the invention in a frame 62. The fifth membrane filter 63 again corresponds essentially to the third membrane filter 37.

[0044] The frame 62, welded from stainless steel profiles, has a rectangular basic shape with two vertical supports 64 and an upper cross brace 65 made of a U-profile. A downwardly open tray 66 made of folded sheet metal forms the lower cross brace. The tray 66 has wedge-shaped gas outlets 67 open at the sides for the gas to flow from the tray 66 into membrane elements 68 of the fifth membrane filter 63.

[0045] The membrane elements 68 are connected to a permeate collector 70 via headers 69. A permeate outlet pipe 71 is connected to the top of the permeate collector 70 to discharge the resulting permeate from the permeate collector 70.

[0046] Figure 5bshows in detail the membrane element 68 of the fifth membrane filter 63. This has a tube 72 that surrounds membranes 73 of the membrane element 68, and at the top a closing ring 74 with a hook-shaped holder 75 at the front of the membrane element 68. The membranes 73 are also hollow fiber membranes in this case.

[0047] For mounting the fifth membrane filter 63, the pre-assembled membrane element 68 is suspended with the bracket 75 at the top of the cross member 65 on the also pre-assembled frame 62. The header 69 then automatically swings in front of the permeate collector 70 and can then be pushed almost horizontally between the beams 76 with little effort.

[0048] Figure 6 shows a sixth membrane filter 77 according to the invention, which again corresponds in basic structure to the first membrane filter 1. Unlike the first membrane filter 1, the headers 78 consist only of the membrane blocks 79 and do not have an enclosing housing.

[0049] Further deviating, the membrane elements 80 are enclosed by a common, longitudinally continuous tube 81, which has the inflow opening 82 for the liquid and the gas at the bottom.

[0050] The permeate outlets 83 at the headers 78 penetrate the pipe 81 and open into a tubular permeate collector 85 running horizontally next to the pipes 81 at a header height 84 of the headers 78.

[0051] In the figures are 1 Membrane filter 2 Membrane element 3 Permeate collector 4 Header height 5 Channel 6 Permeate opening 7 Beam 8 Recess 9 Groove 10 Membrane 11 Tube 12 Header 13 Housing 14 Permeate outlet 15 Outlet direction 16 Overhang 17 Cam 18 Membrane block 19 Sealing layer 20 Permeate collection chamber 21 Collar 22 Sealing ring 23 Inlet opening 24 Membrane filter 25 Permeate collector 26 (further) header height 27 (further) permeate collector 28 Membrane element 29 Membrane 30 (further) header 31 Housing 32 Permeate outlet 33 Overhang 34 Cam 35Header 36Membrane block 37Membrane filter 38Header 39Geyser element 40Housing 41Gas collection chamber 42Outlet device 43Gas lift channel 44Baffle area 45Outflow channel 46Membrane element 47Hole 48Permeate collector 49Outlet direction 50Upper part 51Lower part 52Groove 53Membrane filter 54Membrane element 55(additional) membrane element 56(additional) header height 57Header height 58(additional) header 59(additional) permeate collector 60Header 61Geyser element 62Frame 63Membrane filter 64Support 65Cross brace 66Trough 67Gas outlet68Membrane element 69Header 70Permeate collector 71Permeate outlet tube 72Tube 73Hollow fiber membrane 74End ring 75Bracket 76Hollow 77Membrane filter 78Header 79Membrane block 80Membrane element 81Tube 82Inlet opening 83Permeate outlet 84Header height 85Permeate collector

Claims

1. A membrane filter (1, 37, 53, 63, 77) for submerged operation for filtering a liquid through membrane elements (2, 46, 54, 68, 80) horizontally arranged adjacent to one another and respectively having the following features: - membranes (10, 73) arranged in a vertical longitudinal direction and configured to filter a liquid permeate from the liquid; - a header (12, 38, 60, 69, 78) arranged at a header level (4, 57, 84) and including a permeate collection cavity (20), wherein respective permeate sides of the membranes (10, 73) are connected to the permeate collection cavity (20), and a permeate outlet (14, 83) configured to drain the permeate in an outlet direction (15, 49) horizontally from the permeate collection cavity (20); and - a tube (11, 72, 81) that adjoins on top at a respective header of the headers (12, 38, 60, 69, 78) and laterally envelops the membranes (10, 73) of the respective membrane element (2, 46, 54, 68, 80), wherein the permeate outlets (14, 83) are connected at a horizontally extending common permeate collector (3, 48, 70, 85) that drains the permeate from the membrane filter (1, 37, 53, 63, 77), characterized in that the permeate collector (3, 48, 70, 85) is arranged at the header level (4, 57, 84) adjacent to the headers (12, 38, 60, 69, 78).

2. The membrane filter (1, 37, 53, 63) according to the preceding claim, characterized by protrusions (16) and recesses (8) at the headers (12, 38, 60, 69, 78) and at the permeate collector (3, 48, 70, 85), wherein the protrusions (16) protrude into the recesses (8) and fix the headers (12, 38, 60, 69) in the longitudinal direction at the permeate collector (3, 25, 48, 70, 85).

3. The membrane filter (1, 37, 53, 63) according to one of the preceding claims, characterized by bars (7, 47, 76) extending in the outlet direction (15, 49) and arranged at the permeate collector (3, 48, 70, 85), wherein two respective bars of the bars (7, 47, 76) support one of the headers (12, 38, 60, 69) horizontally and transversal to the outlet direction (15, 49) at the permeate collector (3, 48, 70, 85).

4. The membrane filter (1, 37, 53, 63) according to the preceding claim, characterized by interlocking connections between the bars (7, 47, 76) and the headers (12, 38, 60, 69), wherein the interlocking connections fix the headers (12, 38, 60, 69) in the outlet direction (15, 49) at the permeate collector (3, 48, 70, 85).

5. The membrane filter (1, 37, 53, 63, 77) according to one of the preceding claims, characterized in that the membranes (10, 73) are configured as hollow fiber membranes individually closed on top.

6. The membrane filter (53) according to one of the preceding claims, characterized by an additional header level (56) above the header level (4, 57, 84), wherein respective permeate sides of additional headers (58) are connected to an additional permeate collector (59) at the additional header level (56).

7. The membrane filter (37, 53, 63) according to one of the preceding claims, characterized by geyser elements (39, 61) arranged at bases of the headers (38, 60) and respectively including a downward open gas collection cavity (41) configured to collect an inflowing gas, and an outlet device (42) configured for pulsating exhaust of the gas into the respective header (38, 69).

8. A method for producing a membrane filter (1, 37, 53, 63, 77) for submerged operation for filtering a liquid through membrane elements (2, 46, 54, 68, 80) horizontally arranged adjacent to one another and respectively having the following features: - membranes (10, 73) arranged in a vertical longitudinal direction and configured to filter a liquid permeate from the liquid; - a header (12, 38, 60, 69, 78) arranged at a header level (4, 57, 84) and including a permeate collection cavity (20), wherein respective permeate sides of the membranes (10, 73) are connected to the permeate collection cavity (20), and a permeate outlet (14, 83) configured to drain the permeate in an outlet direction (15, 49) transversal to the longitudinal direction from the permeate collection cavity (20); and - a tube (11, 72, 81) that adjoins on top at a respective header of the headers (12, 38, 60, 69, 78) and laterally envelops the membranes (10, 73) of the respective membrane element (2, 46, 54, 68, 80), wherein the permeate outlets (14, 83) are connected at a horizontally extending common permeate collector (3, 48, 70, 85) that drains the permeate from the membrane filter (1, 37, 53, 63, 77), characterized in that the permeate collector (3, 48, 70, 85) is arranged at the header level (4, 57, 84) adjacent to the headers (12, 38, 60, 69, 78).

9. The method according to the preceding claim, characterized in that the headers (12, 38, 60, 68) are connected at the permeate collector (3, 48, 70) exclusively by form locking.

10. The method according to claim 8 or 9, characterized in that the protrusions (16) and the recesses (8) at the headers (12, 38, 60, 69) and at the permeate collector (3, 48, 70) are inserted into one another horizontally.

11. The method according to the preceding claim, characterized in that the headers (12, 38, 60, 69) are inserted at the permeate collector (3, 48, 70) in the outlet direction (15, 49) between two respective bars (7, 47, 76), and thus the protrusions (16) are advantageously inserted into the recesses (8).

12. The method according to the preceding claim, characterized in that interlocking connections between the bars (7, 47, 76) and the headers (12, 38, 60, 69) interlock upon insertion.

13. The method according to one of the claims 8 - 12, characterized in that the membrane elements (68) are initially inserted with an upper support (75) into a top of a frame (62) and the respective header (69) is connected at the permeate collector (70) thereafter.

14. The method according to one of the claims 8 - 13, characterized in that geyser elements (39, 61) are arranged at the permeate collector (48, 70) below the headers (38, 60, 69) between two respective bars (7, 47, 76) wherein the geyser elements respectively include a downward open gas collection cavity (41) configured to collect an inflowing gas and an outlet device (42) configured for pulsating exhausting of the gas into the respective header (38, 60, 69).