DEVICE FOR FILTERING AND SEPARATING FLUID MEDIA

Abstract

A device (10) for filtering and separating flow media (11) by reverse osmosis and ultrafiltration is proposed, comprising a plurality of stacked spacer elements (12), wherein a filter element (14) is enclosed between each substantially disc-shaped spacer element (12) provided with a central hole (13), which guides the flow medium (11) and is enclosed by the flow medium (11), and a central clamping bolt (15) which holds the stack of spacer elements (16), which is bounded on both sides by a first and a second inner end element (17, 172) and a first and a second outer end element (18, 183), together as a unit, wherein the unit is enclosed in a pressure-tight housing (19).For this purpose, the first and second outer end elements (18, 183) are received in the housing (19) without sealing, whereas the first and second inner end elements (17, 172) are received in the housing (19) sealed against the inner wall (190).

Description

[0001] The invention relates to a device for filtering and separating fluids by reverse osmosis and ultrafiltration, comprising a plurality of stacked spacer elements, wherein a filter element is enclosed between each of the substantially disc-shaped spacer elements, which are provided with a central hole and guide the fluid and are enclosed by the fluid, and a central clamping bolt, which holds the stack of spacer elements, which is bounded on both sides by a first and a second inner end element and a first and a second outer end element, together as a unit, wherein the unit is enclosed in a pressure-tight housing.

[0002] A device of this type is known (EP-B-0 289 7409). Devices of this type have been known for a long time and are used for a wide variety of separation tasks, not only for separating liquid flow media but also, for example, for gas separation, whereby these devices, whether for separating liquid media or gaseous media, have more or less the structure as outlined for the device described here with its essential design features.

[0003] A characteristic of these devices is that they are regularly assembled or linked in series and / or side-by-side in order to fulfill the specified separation task with high efficiency, i.e., with high effectiveness. For example, such devices are used for seawater treatment, i.e., for producing drinking water from seawater or for producing irrigation water for plants and plantations; for wastewater treatment, which arises in both industrial and private sectors; and also, for example, for the purification of leachate, which accumulates, for instance, at the bottom or edges of landfills.All of the aforementioned exemplary applications share one common requirement: that these devices must operate with a high degree of reliability and be maintenance-free. This is because the design principle of these devices allows for repairs in the event of a detected defect only through a very complex disassembly, replacement of the defective components, and reassembly. The paramount requirement for such devices is therefore to ensure defect-free and maintenance-free operation over extended periods, without incurring high manufacturing costs.

[0004] As is well known to experts, these requirements—namely high operational reliability, low maintenance, and low production costs—involve strongly conflicting parameters, a fact clearly evident in other devices known in the prior art, and not just in the device of this type. Furthermore, for certain applications, the target product to be produced by the device, which typically exits as a permeate but sometimes as a retentate, must be of high purity and must not be contaminated by foreign substances during the actual separation process of the medium to be separated within the device. Such contamination could impair the required quality of the target product or prevent the required high purity of the target substance from being guaranteed.

[0005] For this reason, these devices are very complex in terms of their design and the materials used for their construction, meaning they can only be realized at high production costs. As a result, although such devices would be ideally suited for this purpose, they are not used for certain separation tasks. Consequently, the inherently ineffective thermal separation of liquid mixtures, gas mixtures, and liquid / gas mixtures is often used, and sometimes separation is even completely dispensed with, with the still significant environmental impacts that result from it.

[0006] It is therefore an object of the present invention to provide a device of the type mentioned above which has a design such that the adverse properties of known devices, as described above, are eliminated within the limits of what is technically possible, the device can be realized in such a way that it can be manufactured much more cost-effectively without having to make compromises with regard to the expected purity of the target medium compared to the purity of the target medium achievable with known devices, which also does not introduce any impurities into the medium to be separated or the target medium, which is more cost-effective to provide and easier to assemble and disassemble, yet exhibits as long a service life as previously known devices with complex conventional designs and has a considerably lower weight than previous devices of this type.

[0007] The problem according to the invention is solved by the fact that the first and second outer end elements are received in the housing without sealing, whereas the first and second inner end elements are sealed against the inner wall of the housing and received in it.

[0008] The advantage of the solution according to the invention lies essentially in the fact that the first and second outer end elements only need to be designed as simple disc-shaped elements, i.e., they can be provided as plate-shaped semi-finished products that merely need to be brought into their suitable outer shape, e.g., as a disc with a circular cross-section, by a turning operation, a milling operation, or by punching. Since no external seal against the inner wall of the housing or the like is required, unlike in prior art designs that require complex, circumferential lip seals between the outer end elements and the inner wall of a housing that is typically cylindrical in cross-section, this is unnecessary.This simple principle according to the invention applies in principle to both sides of the stack of spacer elements, so that in fact both outer end elements in the basic version can be manufactured simply and cost-effectively in the manner described above.

[0009] The advantage of the solution according to the invention also lies in the fact that only the two inner end elements, which directly border the stack of spacers next to the outer end elements, need to be designed to be sealable against the inner wall of the housing. In prior art designs of this type, the sealing elements are generally present in both the two outer end elements and the two inner end elements, and they jointly seal against the inner wall of the housing. This further complicates both the assembly of the stack of spacers, including the inner and outer end elements of the unit thus formed, within the housing, as well as the disassembly of the stack of spacers, i.e., the removal or extraction of the entire unit.

[0010] According to an advantageous embodiment of the invention, the inner end elements are made of plastic. This distinguishes this device from all known devices of this type, including generic devices in which the inner end elements are typically made of high-grade stainless steel. Making the inner end elements from plastic has the enormous advantage that the production costs of plastic for this purpose are generally much lower than the production costs for end elements made of high-grade stainless steel, and the processing of the plastic, for example to shape the inner end elements, is also significantly less than with the aforementioned high-grade steel.

[0011] It is particularly advantageous to use polyoxymethylene (POM) as the plastic. Polyoxymethylene offers the significant advantage of high strength at a low weight and, due to its inertness, does not impair the purity of the target product produced by the device, even with respect to aggressive media being separated. This plastic can be used in the device according to the invention for both drinking water and food production. Furthermore, the processing costs for this plastic are considerably lower than those for an inner end element made of high-grade steel; that is, the effort required for mechanical processing by turning, milling, drilling, etc., is significantly less than for an inner end element made of high-grade steel.

[0012] To create a simple yet reliable seal between the inner end elements and the inner wall of the device housing, which must be removable, it is advantageous to seal the inner end elements against the inner wall of the housing by means of a sealing element that runs around each end element. Preferably, a groove-like recess is provided around each inner end element in which the respective sealing element can be arranged or embedded. The sealing element can, for example, be designed as a U-shaped lip seal, the pressure of which can be further increased by a circumferential ring arranged within the lip seal, or it can be securely held in place in the circumferential groove.

[0013] Unlike devices known in the prior art, including the device of this invention, the feed to the medium to be separated and the discharge of the concentrated medium, the retentate, are preferably sealed against the first inner end element by means of a sealing element. This means that, in the inventive design described here, the seal for the feed and the seal for the discharge are located in the inner end element.The adjacent outer end element does not need to have any sealing elements for this purpose either, which further increases the aforementioned advantage of the design according to the invention compared to known designs, namely that all sealing measures need to be provided exclusively in the inner end element, whereas the adjacent outer end element, with regard to this design detail, only needs to be equipped with simple through holes for the feed and discharge, which simplifies the manufacture of the adjacent outer end element and can therefore be accomplished more cost-effectively than previous designs in which the seals for the feed and discharge were provided either exclusively or additionally in the outer end element.

[0014] The sealing element itself can consist of any suitable or appropriately shaped sealing elements, but preferably the sealing element is possibly in the form of an O-ring made of elastomeric material, e.g. plastic or rubber, whereby this elastomeric material may also be reinforced with fabric.

[0015] According to a further advantageous embodiment of the device, the sealing element is received in a groove that essentially surrounds a hole arranged essentially centrally in the first end element, in which, for example, the aforementioned O-ring is positioned as a sealing element.

[0016] According to yet another advantageous embodiment of the invention, the second inner end element is sealed against the central clamping bolt by means of a sealing element, wherein in this case, too, the sealing element can preferably be in the form of an O-ring, but in this case, any other suitable sealing elements or shapes, e.g., lip seals, are also possible, and wherein these seals can also be made of elastomeric material, e.g., rubber or plastic, possibly reinforced with fabric.

[0017] Here too, it is advantageous, in order to ensure that the sealing element can be securely fixed relative to the second inner end element, exactly as described above in connection with the first inner end element, to accommodate the sealing element in a groove that essentially surrounds a hole located essentially centrally in the second inner end element, which, for example, is rectangular in cross-section exactly like the groove in the first inner end element. This not only ensures the sealing effect against the central clamping bolt, possibly with the intermediate positioning of a respective sleeve, but also prevents the sealing element from being pushed out of its position in the inner sealing elements during the assembly of the filter element stack and the subsequent positioning of the inner end elements on both sides.

[0018] Since, as explained above, the inlet and outlet are sealed within the inner end element, the adjacent outer end element serves only to secure the inlet and outlet, although this securing could also be provided in the inner end element. In a design where the inlet and outlet are not secured within the inner end element beyond a seal, it is advantageous to design the inlet and / or outlet to be detachably fastened to the first outer end element. This can preferably be achieved simply by providing the inlet and outlet with appropriately designed threaded projections that can be screwed into corresponding internal threads of the first outer end element. This also allows for easy disassembly of the inlet and outlet without damaging or impairing a sealing connection.

[0019] The invention will now be described in detail with reference to the following schematic drawings, using an exemplary embodiment as an example. These drawings show: Fig. 1 shows a cross-sectional view of the basic structure of the device according to the invention, Fig. 2 shows a section of the device in cross-section. Fig. 1 , in particular the area of ​​the seal of the feed and discharge in the first inner end element, in relation to the Fig. 1 enlarged scale, Fig. 3 a section in cross-section from the Fig. 1 , in particular the second inner and outer end element, in relation to the Fig. 1 enlarged scale and Fig. 4 very schematically a battery consisting of a plurality of devices connected in series in conjunction with a control and regulation system and a supply of drinking water, which is produced from seawater by means of the devices.

[0020] It will initially be on Fig. 1Reference is made to the basic structure of the device 10 according to the invention.

[0021] The device 10 comprises as its central element a unit consisting of a plurality of stacked spacer elements 12, which are essentially disc-shaped. Each of these spacer elements 12 encloses a filter element 14 between them, which can, for example, be in the form of a so-called membrane cushion. The membrane cushions have a material-selective membrane layer on their two outer flat surfaces, which typically consists of polymeric materials and is joined to one another at its circumferential edges, or, if these are, for example, plate-shaped, by means of ultrasonic welding. The membrane cushions typically have a central hole through which the permeate, obtained from the medium to be separated or the flow medium 11 by means of the device 10, exits. This separation mechanism and the construction of such a stack of spacer elements 16 are known, wherein, for example,Such a spacer element is described in detail by way of example in the aforementioned EP-B-0 289 740. A further discussion of the structure of the spacer elements 12 and the filter elements 14, which are regularly designed as membrane cushions, is therefore not necessary here, as they are already known to the experts.

[0022] The flow medium 11 flows completely through the stack of spacer elements 16 in a regular meandering pattern from an inlet to an outlet, whereby the flow medium 11, being suitably guided and directed via the spacer elements 12, flows over or around all filter elements 14 of the stack of spacer elements 16.

[0023] A central clamping bolt 15, suitably secured by nuts 15, 150, 151 and 152, holds the stack of spacer elements 16, which is bounded on both sides by a first and a second inner end element 17, 172 and a first and a second outer end element 18, 183, together as a unit. By means of the central clamping bolt 15 and the threaded nuts 150, 151, 152 that interact with it, a sufficiently large pressure is exerted on the stack of spacer elements 16 consisting of spacer elements 12 and the filter elements 14 enclosed between them, which are provided around their central holes by means of suitably designed sealing elements, such a large pressure that the flow medium 11 to be separated can flow around all the spacer elements 12 or the filter elements 14 of the entire stack of spacer elements 16 in a meandering pattern, but cannot enter the central hole 13 of the spacer element 12, which together with all the holes 13 forms a permeate drainage channel.

[0024] This principle is also known to experts, so further discussion of it is not necessary at this point.

[0025] The stack of spacers 16 according to the device 10 described here has such first and second outer end elements 18, 183, which are designed here as simple discs made of suitable strong materials, e.g., steel, but possibly also plastic. Since the two outer end elements 18, 183 only have a force-transmitting and supporting effect, but do not come into contact with the flow medium 11 to be separated, they can be enclosed without sealing in a housing 19, which only needs to be provided as a tube open at both ends, possibly even as a semi-finished product. The first and second outer end elements 18, 183 can be made of any suitable material; high-grade steels or other materials do not need to be used, since their only function is to exert a sufficiently large force on the stack of spacers 16 via the threaded nuts 150, 151, and 152.

[0026] However, the first and second inner end elements 17, 172, which are directly adjacent to the outer first and second end elements 18, 183, have sealing means so that they can be sealed against the inner wall 190 of the housing 19, i.e. the entire stack of spacer elements 16 is sealed in the housing 19 via these sealing means.

[0027] In contrast to the outer end elements 18, 183, see also the larger partial representations according to. Fig. 2 and 3The inner end elements 17, 172 are made of plastic, e.g., in the form of polyoxymethylene (POM). These inner end elements 17, 172 can also be designed as disc-shaped elements. In the embodiment shown in the figures, the housing has a circular cross-section, so that the inner end elements 17, 172, like the outer elements 18, 183, also have a circular cross-section. They are provided with a groove 178, 179 extending radially around the inner end elements 17, 172, in which sealing elements 20, 200, designed as lip seals, are arranged. The sealing elements 20, 200 form the seal against the inner wall 190 of the housing 19. The sealing elements 20, 200 can have a U-shaped cross-section and can be provided with a radially circumferential reinforcing element to increase the seating and sealing effect of the sealing elements 20, 200.

[0028] Both the first inner end element 17 and the second inner end element 172 each have a through hole 170, 173 formed essentially centrally within them. An internal groove 171, 174 is formed around these holes 170, 173, in which a sealing element 175 is provided. The sealing element 175 can also be in the form of an O-ring made of an elastomeric material, e.g., rubber or plastic, and can additionally be reinforced with fabric or fiber.

[0029] In the embodiment of the device 10 shown in the figures, the sealing element 175 does not interact directly with the central clamping bolt 15, but rather via bushings 28, 29 arranged between the first and second inner end elements 17, 172. These bushings, in turn, interact with the central clamping bolt 15 via corresponding sealing elements 30, which are designed like the sealing elements 175 described above. The sealing variant described here is not strictly necessary, but it simplifies the sealed design of the permeate drainage channel.

[0030] The actual feed 21, which is provided in the form of a connection nozzle for the medium 11 to be separated, the so-called feed, and the discharge 22, also designed as a connection nozzle, through which the concentrated medium 23, the so-called retentate, is discharged, are fixed and pressure-tightly enclosed in the first inner end element 17. A sealing material or sealing elements 24, 25, enclosed in a corresponding through-hole of the inner end element 17 or in a groove therein, serve as a seal around the feed 21 or the discharge 22, respectively (see in particular [reference]). Fig. 2 . These sealing elements 24, 25 can also be in the form of an O-ring and made of elastomeric material such as rubber or plastic, possibly reinforced with fabric.

[0031] The inlet 21 and the outlet 22 are fastened in a hole formed in the first outer end element 18, which has an internal thread 184, and engage with the corresponding external thread of the inlet 21 and outlet 22. The holes formed in the first outer end element 18 for the inlet and outlet 22 align with the corresponding holes in the holes of the first inner end element 17, which are arranged adjacent to each other in the assembled state of the spacer stack 16, so that the sealing elements 24, 25 formed there of the inlet 21 and the outlet 22 seal around a correspondingly formed shaft of the inlet 21 and the outlet 22. The feed 21 and the discharge 22 can thus be pre-assembled and attached in the outer end element 18 before the pre-assembled first outer end element 18 is joined to the first inner end element 17 to form the complete stack of spacer elements 16.

[0032] As already indicated above, during the intended operation of the device 10, the permeate 26, which is regularly the target product to be obtained from the supplied fluid medium 11 with the device 10, is collected in the holes 13 of all spacer elements 12 and guided parallel to or around the central clamping bolt 15 to the discharge 27 and discharged from the device as permeate 26, see in particular also Fig. 2 The flow medium 11 to be separated is fed into the device 10 via the feed 21 and is guided between the inner wall 190 and the outer boundary of the spacer stack 16, first to the head of the spacer stack 16, as shown in the illustration of Fig. 1 left, see also Fig. 3, and then enters the spacer element stack 16 in the manner described above in sketch form and meanders through the spacer element stack 16 and then exits the spacer element stack 16 as a concentrated medium, i.e. as so-called retentate 23, and leaves the device 10 via the discharge 23. Reference symbol list

[0033] 10 Device 11 Flow medium 12 Spacer element 13 Hole / Spacer element 14 Filter element 15 Central clamping bolt 150 Nut 151 Nut 152 Nut 16 Stack of spacer elements 17 First inner end element 170 Hole / First inner end element 171 Groove / First inner end element 172 Second inner end element 173 Hole / Second inner end element 174 Groove / Second inner end element 175 Sealing element / Clamping bolt 176 Sealing element 177 Hole 178 Groove 179 Groove 18 First outer end element 180 Hole 181 Sealing element 182 Groove 183 Second outer end element 184 Threaded connection 19 Housing 190 Inner wall / Housing 20 Sealing element 200 Sealing element 21 Feed / medium to be separated 22 Discharge / concentrated medium 23 Concentrated medium / retentate 24 Sealing element / feed 25 Sealing element / discharge 26 Permeate 27 Discharge / permeate 28 Bushing 29 Bushing 30 Sealing element

Claims

1. Device (10) for filtering and separating fluids (11) by reverse osmosis and ultrafiltration, comprising a plurality of stacked spacer elements (12), wherein a filter element (14) is enclosed between each of the substantially disc-shaped spacer elements (12) which are provided with a central hole (13) and which guide the fluid (11) and are surrounded by the fluid (11), and a central clamping bolt (15) which holds the stack of spacer elements (16), which is bounded on both sides by a first and a second inner end element (17, 172) and a first and a second outer end element (18, 183), together as a unit, wherein the unit is enclosed in a pressure-tight housing (19), characterized by the fact thatthe first and second outer end elements (18, 183) are received without sealing in the housing (19), whereas the first and second inner end elements (17, 172) are received in the housing (19) sealed against the inner wall (190).

2. Device according to claim 1, characterized by the fact that the inner end elements (17, 172) are made of plastic.

3. Device according to claim 2, characterized by the fact that The plastic is polyoxymethylene (POM).

4. Device according to one or more of claims 1 to 3, characterized by the fact that the inner end elements (17, 172) are sealed against the inner wall (190) of the housing (19) by means of a sealing element (20, 200) which runs around the end element (17, 172).

5. Device according to one or more of claims 1 to 4, characterized by the fact thatthe feed (21) of the medium (11) to be separated, the so-called feed, and the discharge (22) of the concentrated medium (23), the so-called retentate, are sealed against the first inner end element (17) by means of a sealing element (24, 25).

6. Device according to claim 5, characterized by the fact that the sealing element (24, 25) is designed in the form of an O-ring.

7. Device according to one or more of claims 1 or 6, characterized by the fact that a sealing element (175) is received in a groove (171) which is substantially circumferential around a hole (170) which is substantially centrally located in the first inner end element (17).

8. Device according to one or more of claims 1 to 7, characterized by the fact that the second inner end element (172) is sealed against the central clamping bolt (15) by means of a sealing element (174).

9. Device according to claim 8, characterized by the fact that the sealing element (174) is designed in the form of an O-ring.

10. Device according to one or both of claims 8 or 9, characterized by the fact that the sealing element (175) is received in a groove (178) which essentially surrounds a hole (173) which is arranged essentially centrally in the second inner end element (172).

11. Device according to one or more of claims 5 to 10, characterized by the fact that the feed (21) and / or the discharge (22) is detachably mounted in the first outer end element (18).

12. Device according to claim 11, characterized by the fact that the feed (21) and / or the discharge (22) is received in the first outer end element (18) by means of a threaded connection (184).