Filtering device

Abstract

The utility model relates to a filtering device for a liquid medium, in particular for water, which comprises a hollow support body, the hollow support body is provided with a channel for the liquid medium, the hollow support body is provided with a first filter, the first filter is designed to be a surface filter, and the surface filter is provided with a second filter. Wherein the filtering device is provided with a backwashing device so as to remove impurities of the first filter. The filter device is characterized in that a second filter is assigned to the support body, the second filter being designed as a deep filter, and the second filter having a porous body made of a sintered plastic material.

Description

Technical Field

[0001] The utility model relates to a filtering device for liquid media, especially for water. The filtering device includes a hollow support body which has a channel for the liquid medium. A first filter is allocated to the hollow support body. The filtering device has a backwashing device to remove impurities from the first filter. Background Art

[0002] Filtering of liquid media is carried out to remove impurities from the liquid media. For example, it is known to filter water in domestic facilities, such as to filter out particulate impurities.

[0003] US2005 / 0115886 A1 describes a filtering device for liquid media, which includes a plurality of filters.

[0004] Filter elements for drinking water are known from RU 174 088U1 and US2006 / 0049096 A1, which contain activated carbon. Dissolved substances, such as chlorine, can also be removed from water using activated carbon.

[0005] There is a need for such filtering devices that achieve good filtering effects even for small particles. For this purpose, fine filters can be used, but their disadvantage is that they tend to clog relatively quickly. This requires manual intervention, such as especially replacing the filter. Summary of the Utility Model

[0006] The purpose of the utility model is to provide a filtering device that has a good filtering effect on small particles and also has a long service life.

[0007] The utility model provides a filtering device for liquid media, especially for water. The filtering device includes a hollow support body which has a channel for the liquid medium. A first filter is allocated to the hollow support body. The first filter is designed as a surface filter. The filtering device has a backwashing device to remove impurities from the first filter. A second filter is allocated to the support body. The second filter is designed as a depth filter. And the second filter has a porous body made of sintered plastic material.

[0008] Multiple filtration of a liquid medium can be achieved using these measures. For this purpose, the filtration device is provided with a first filter, which is designed as a surface filter. The surface filter can be used to intercept impurities mainly at the surface of the first filter. In addition, a second filter is provided, which is designed as a depth filter and has a porous body made of sintered plastic material. The depth filter has a depth filtration material in which the particles to be filtered can be intercepted in the grooves of the depth filtration material. Through this multi-stage combination, particulate impurities, even small-sized impurities, can be separated from the liquid medium particularly effectively. In particular, when flowing through the first and second filters, particles larger than the pores of the corresponding filter are separated out. Through this combination according to the patent requirements, the possibility of filter clogging is significantly reduced. In addition, the impurities of the first filter can be removed using a backwashing device without replacing the first filter, for example, by temporarily reversing the flow direction. Using all these measures, the service life of the filtration device can be significantly extended. This greatly reduces the maintenance workload and maintenance costs. In addition, an undesired pressure drop at the filter is avoided. The claimed filter is particularly suitable for filtering the water in the public water supply when it enters domestic facilities. The porous body can preferably be made of plastic particles that are connected together by sintering. The filtration device is suitable for different liquid media. Although particularly suitable for water, the filtration device can also be used for other liquid media, such as dispersions.

[0009] The following describes the preferred features of the filtration device, which further promote the above advantages individually and jointly.

[0010] In a preferred embodiment of the present utility model, one of the first and second filters is arranged inside the hollow support body, and the other of the first and second filters is arranged outside the hollow support body. Preferably, the first filter is arranged inside the hollow support body, and the second filter is arranged outside.

[0011] According to the present utility model, preferably, the sintered thermoplastic has hydrophobic properties. This contributes to achieving a good filtration effect in an unexpected way. In particular, the thermoplastic can be non-polar.

[0012] Preferably, the porous body comprises a sintered thermoplastic, such as polyethylene. This material can not only achieve a good filtration effect but is also acid and alkali resistant. In addition, favorable hydrophobic properties can be obtained using polyethylene (PE).

[0013] Preferably, the porous body is designed as an open pore structure.

[0014] Preferably, the porous body has filtration channels through which the liquid medium can pass through the porous body.

[0015] According to the present utility model, preferably, the porous body has pores with a pore diameter between 5 μm and 100 μm. Particularly preferably, the average pore diameter of the porous body is between 10 μm and 30 μm. The average pore diameter can be determined by the bubble pressure test described below. Filter particles larger than this pore diameter are intercepted. This enables the second filter to also filter very small particles.

[0016] A further improved solution is that the porosity of the porous body is between 40% and 60%. This helps to achieve good filtration performance while having a long filter service life. The porosity represents the ratio of the cavity volume to the total volume of the porous body.

[0017] Preferably, the porous body has a density between 1.6 g / cm 3 and 1.7 g / cm 3 This helps to achieve good filtration performance while having a long filter service life. These densities can be achieved by sintering under pressure and / or using fillers.

[0018] An advantageous technical solution of the present utility model is that in the bubble pressure test, the porous body has a bubble point when the pressure difference at the porous body is between 0.003 bar and 0.005 bar. It has been proven that good filtration can be achieved while having a particularly long service life.

[0019] The pressure difference at the bubble point can be determined by the bubble pressure test according to the standard DIN EN 13443-2:2007-10. In this case, the filter material loaded with liquid is pressurized with gas from one side, and the pressure is increased until the gas displaces the liquid from the pores and passes through the filter material. This can be observed by the formation of bubbles. The pressure at which the first bubble forms is called the bubble point. The size of the largest pores can be derived from the pressure at the bubble point. If the pressure is further increased, the open bubble point can be determined, which can be regarded as a measure of the average pore size. Preferably, for this porous body, the open bubble point is reached when the pressure difference at the porous body is between 0.005 bar and 0.02 bar (preferably greater than 0.0075 bar and / or less than 0.015 bar).

[0020] A preferred technical solution of the present utility model is configured such that the porous body has a surface that has an average roughness value Ra greater than 15 μm in at least a part thereof. Preferably, the above-mentioned average roughness value Ra is greater than 17 μm. Preferably, the part of the surface having the average roughness value Ra comprises at least 25% (particularly preferably at least 40%) of the surface of the porous body. Preferably, the average roughness value Ra is less than 30 μm. The average roughness value Ra can be determined according to the standard DIN EN ISO 21920-2:2021-12. The present utility model has recognized that by using a porous body with the above-mentioned average roughness value, a particularly good filtering effect can be achieved while having a long service life.

[0021] According to the present utility model, preferably, the second filter is cylindrical and has a cylindrical side surface. Preferably, the filtering unit is adapted such that the liquid medium flows through the second filter in a direction perpendicular to the cylindrical side surface. Preferably, the second filter is designed to be tubular and open at both sides.

[0022] If the cylindrical side surface of the second filter has a material thickness between 1 mm and 5 mm, the advantages of the present utility model are further enhanced. Preferably, the material thickness is greater than 1.5 mm and / or less than 3 mm, particularly preferably less than 2.5 mm.

[0023] Another preferred improvement is configured such that the filtering unit is arranged to first flow through the first filter and then through the second filter during operation.

[0024] According to the present utility model, preferably, the first filter has filter openings, and the opening width of these filter openings is greater than 20 μm. In particular, the opening width of the filter openings of the first filter can be greater than 25 μm. Preferably, the opening width is less than 50 μm, particularly preferably less than 35 μm. This contributes to good separation and a long service life.

[0025] Preferably, the first filter comprises a sheet-like structure having fibers, and channels are formed between these fibers. These channels constitute the filter openings. The fibers can particularly be made of plastic and / or metal. As the metal material, stainless steel is particularly preferred. The plastic material preferably comprises polysulfone compounds, such as particularly polyethersulfone (PES), whereby in this combination, particularly good filtering characteristics are obtained while having a long service life.

[0026] Preferably, the fibers are arranged in a fiber layer or a fiber fabric.

[0027] A preferred embodiment is provided such that the fibrous fabric has warp and weft yarns which are arranged to have a mesh size greater than 20 μm and less than 50 μm. Preferably, the mesh size is greater than 25 μm and / or less than 35 μm. In this way, channels forming the filter openings can be formed.

[0028] Preferably, the first and second filters are designed as particulate filters. Here, it can be particularly provided that the first filter is designed for coarse filtration and the second filter is designed for fine filtration.

[0029] Preferably, the channels connect the interior space of the support body to the outside of the support body. Preferably, the channels include elongated slits formed in the support body. Preferably, the maximum length of one of these slits is more than twice the shortest width of the slit.

[0030] According to the present utility model, it can be provided that the support body includes a cylindrical portion, and the elongated slits are arranged in the cylindrical portion. Preferably, the cylindrical portion of the support body is coaxially arranged with the second filter.

[0031] Preferably, the first filter is arranged on the inner side of the cylindrical portion, and the second filter is arranged on the outside of the cylindrical portion. Preferably, the inner side of the support body constitutes the contact surface for the first filter.

[0032] Preferably, the elongated slits have a longitudinal direction which extends in the circumferential direction of the cylindrical portion.

[0033] Preferably, the elongated slits are arranged in rows. Preferably, each of these rows includes more than 10 elongated slits. Preferably, between 4 rows and 15 rows of elongated slits are provided in the cylindrical portion.

[0034] Preferably, continuous longitudinal partition strips are designed between these rows, and these longitudinal partition strips separate two rows of the elongated slits from each other.

[0035] Preferably, the filter unit has a supply line for the liquid medium to be filtered and a discharge line for the filtered liquid medium. Preferably, the filter unit further includes a drain for the liquid medium accumulated during flushing. Preferably, the supply line and the discharge line are coaxially arranged in a single connecting element.

[0036] A preferred technical solution is provided such that the filter unit has a pressure reducer. Preferably, the pressure reducer is integrated in the filter unit. Further preferably, the pressure reducer has an actuator via which the pressure reduction can be adjusted.

[0037] According to a preference of the present utility model, the filtering unit has a housing surrounding the support body. Preferably, an inspection window is arranged in the housing, through which the second filter can be seen.

[0038] According to a preference of the present utility model, the filtering device has a control unit for automatically activating the backwashing device. For this purpose, the backwashing device can include a solenoid valve, which opens the flow channel to perform backwashing.

[0039] Furthermore, the backwashing device can include a spring, which is configured to close the flushing valve of the backwashing device.

[0040] The backwashing device can be periodically activated by the control unit after a period of time stored in the control unit.

[0041] Advantageously, it can be arranged that the control unit includes a sensor device, which detects the pressure difference at the first filter and / or the second filter and activates the backwashing device when the measured pressure difference is higher than a set value of the pressure difference stored in the control unit.

[0042] Preferably, the second filter is designed as a tubular filter element, which is replaceably arranged in the filtering device.

[0043] Preferably, the second filter is replaceably arranged on the support body. Description of the Drawings

[0044] A further object, feature, advantage and application possibility of the present utility model become clearer from the following description of embodiments in conjunction with the drawings. Herein, all described and / or pictorially depicted features constitute the subject matter of the present utility model, whether individually or in any meaningful combination, even independently of the overview of the individual claims or their dependencies.

[0045] Wherein:

[0046] Figure 1 is a side view of the filtering device;

[0047] Figure 2 is Figure 1 a perspective view of the filtering device in , without showing the second filter;

[0048] Figure 3 is Figure 1 a schematic view of the support body of the filtering device in , with the second filter partially shown;

[0049] Figure 4a is Figure 1 a perspective view of the second filter of the filtering device in ;

[0050] Figure 4b is Figure 4aSide view of the second filter in;

[0051] Figure 4c is Figure 4b Cross-section of the second filter along line A-A in;

[0052] Figure 4d is Figure 4c Enlarged detail view of part X of the second filter in;

[0053] Figure 5 Is the measurement result of determining the bubble point at different porous bodies of the second filter;

[0054] Figure 6 Is the measurement result of determining the roughness at different porous bodies of the second filter;

[0055] Figure 6a Is a comparison chart of the treated water volume and pore size obtained from the measurement results;

[0056] Figure 7 Is a schematic cross-sectional view of the first filter;

[0057] Figure 8 Is a cross-section of the support body with the first and second filters. Detailed description of the specific implementation

[0058] Figure 1 Shows a filtering device 1 for a liquid medium, especially for water. The filtering device 1 has a supply line 2 and a discharge line 3 for the liquid medium. The liquid medium enters the filtering device 1 through the supply line 2, and the filtered liquid medium leaves the filtering device through the discharge line 3. In the shown embodiment, the supply line 2 and the discharge line 3 are coaxially arranged in a combined connection element, where the discharge line 3 is arranged to surround the supply line 2. However, the supply line 2 and the discharge line 3 can also be arranged in separate connections in a manner different from that shown in the figure.

[0059] The filtering device 1 has a head 4. At its bottom surface, a housing 5 is arranged, and a support body 6 is arranged in the housing. The liquid-tight housing 5 has an inspection window 7, so that the inside of the housing 5 is visible.

[0060] At the support body 6, a first filter 8 and a second filter 9 are arranged in the manner described in more detail below. To better show the support body 6, the second filter 9 is not shown in Figure 1 in.

[0061] The filtration device 1 is provided with a backwashing device 11 which is arranged in the head 4. By means of the backwashing device 11, the flow direction in the filter can be reversed so as to remove the impurities intercepted by the first and / or second filters 8, 9. Then, the liquid containing impurities can be discharged from the filtration device 1 through the drain port 10.

[0062] In the illustrated embodiment, the backwashing device 11 has an electromagnetic valve 20 which opens the flow channel to perform backwashing. The electromagnetic valve 20 has an electrical connection 21 via which the electromagnetic valve 20 can be activated by the control unit.

[0063] The support 6 has channels 14 for the liquid medium, and these channels communicate the inner space of the support 6 with the outer side of the support 6. In the illustrated embodiment, these channels are designed as elongated slits. Here, the maximum length of the channels 14 designed as slits is more than twice the shortest width of the corresponding slits. Each of these elongated slits has a longitudinal direction which extends in the circumferential direction of the cylindrical part 13.

[0064] The support 6 has a cylindrical part 13 in which the channels 14 are arranged.

[0065] It will be described in more detail below that the first filter 8 is arranged inside the cylindrical part 13. The second filter 9 is arranged outside the cylindrical part 13. Here, the first filter 8 is closely attached to the inner side of the cylindrical part. During operation, the liquid medium first flows through the first filter 8, then through the channels 14 in the support 6, and then through the second filter 9.

[0066] The channels 14 are arranged in rows, and these rows are distributed in the axial direction of the cylindrical part 13. As shown in the figure, each row in these rows 15 includes more than ten elongated slits.

[0067] Longitudinal partition bars 16 are designed between these rows 15, and these longitudinal partition bars separate two rows 15 of the channels 14 from each other.

[0068] The filtration device 1 may have a control unit which automatically operates the backwashing device.

[0069] For this purpose, the control unit may include a sensor device (not shown) which detects the pressure difference at the first filter 8 and / or the second filter 9 and triggers a backwashing process when the measured pressure difference is higher than a set value.

[0070] Figure 2 The filtration device 1 is shown from the side. Figure 1 Shown in the figure is the filtration device 1 without the second filter 9, while Figure 2 shown is the filtration device 1 with the second filter 9. The second filter 9 is arranged outside the support 6.

[0071] Figure 3 shows a support body 6 with a first filter 8 and a second filter 9. The second filter 9 surrounds the cylindrical part 13 and is shown in the lower half of Figure 3 . In the upper half of Figure 3 , the second filter 2 is only partially shown in order to show the cylindrical part 13 with channels 14. The first filter 8 is arranged on the inner side of the cylindrical part 13. During operation, it flows from the inside out through the first filter 8 and the second filter 9. Thus, the first filter 8 arranged at the inner side of the cylindrical part 13 can be supported at the support body 6.

[0072] In the illustrated embodiment, during operation, it first flows through the first filter 8 and then through the second filter. In the illustrated filtering device, it flows from the inside out through the support body 6. Here, the first filter 8 is arranged at the inner side of the support body 6.

[0073] The first filter 8 has filter openings, and the opening width of these filter openings is greater than that of the second filter. In this way, it can be achieved that the first filter 8 is designed for coarse filtration of particles, and the second filter 9 is designed for fine filtration of particles.

[0074] In particular, the first filter may have filter openings with an opening width between 20 μm and 50 μm, preferably 30 μm.

[0075] In particular, the first filter 8 may include a sheet-like structure having fibers, and channels are formed between these fibers. A preferred embodiment is provided such that the fibers of the sheet-like structure are arranged in a fiber fabric. In this way, the first filter 8 can be designed as a surface filter, in which particles are separated as impurities at the surface of the filtering material of the first filter 8.

[0076] The second filter 9 is designed as a depth filter and has a porous body made of sintered plastic material. The porous body includes filter channels here, and the liquid medium can pass through the porous body through the filter channels. At the same time, particles larger than the filter channels are intercepted by the second filter 9. Here, the second filter is designed as a depth filter, in which particles can be intercepted on the cross-section of the filtering material of the second filter 9. Due to the three-dimensional structure of the porous body 17, a good filtering effect is achieved here while having a long service life.

[0077] The porous body 17 is made of sintered thermoplastic and may particularly include polyethylene.

[0078] The average pore size of the porous body 17 is preferably smaller than the average opening width of the first filter 8. In particular, the average pore size of the porous body 17 can be between 15 μm and 35 μm, preferably between 20 μm and 30 μm.

[0079] Figure 4a Figures d to d show embodiments of the second filter 9 of the filtration device 1. Figure 4a And Figure c shows that: the second filter 9 with the porous body 17 is cylindrical and has a cylindrical surface 18. The second filter 9 is configured such that the liquid medium flows through the second filter in a direction perpendicular to the cylindrical surface. As shown, the second filter 9 can be designed as tubular.

[0080] The cylindrical surface 18 of the second filter 9 has a material thickness S, which can in particular be between 1 mm and 3 mm.

[0081] The porosity of the porous body 17 can in particular be between 40% and 60%. This means that 40% to 60% of the porous body is cavities, while the remaining volume is occupied by the plastic material.

[0082] It has been found that if the pores formed by the porous body 17 of the second filter 9 are designed such that a specific value is reached in the so-called bubble point test, a particularly good filtration effect is achieved while having a long service life.

[0083] Figure 5 The measurement results after the bubble point test for different porous bodies 17 are shown. These porous bodies are each designed as cylindrical and have a material thickness S of 2 mm. The measurements are carried out in accordance with DIN EN 13443-2:2007-10.

[0084] The measurement results shown in the figure are for three different filter materials. Filter material L1 is shown on the left, filter material L2 in the middle, and filter material L3 on the right. The corresponding bubble points are labeled B1, B2, and B3.

[0085] The relevant measurement results are shown in Table 1 below.

[0086]

[0087]

[0088] Table 1

[0089] From the determined bubble point or open bubble point, the corresponding pore size D (in micrometers) can be determined according to the following formula:

[0090]

[0091] The above formula is also known as Poiseuille's law. "σ" is the surface tension of the liquid, which is 7.3×10-2 N / m in water at 15 degrees Celsius. "θ" refers to the contact angle formed between the surface of the liquid droplet and the surface of the filter material. "P" is the pressure (in Pascals).

[0092] Even if the average pore size is between 20 μm and 30 μm, good filtration characteristics can be achieved especially with a long service life. The average pore size can be determined by the pressure at the open bubble point.

[0093] Furthermore, it has been proven that the roughness of the porous body 17 reliably indicates whether good filtration effects can be achieved with a long service life.

[0094] Figure 6 The measurement results of the pressure loss of different filter materials are shown. Each of these filter materials was flowed through by a medium containing 5 mg / l of impurities at a rate of 2000 l / h. The measurement results show that the filter materials initially had a rather constant pressure loss after a short break-in period. When the filter material of the second filter 9 was fully loaded, the pressure loss increased sharply. This is the time point when the filter material needs to be replaced. For the filter material L1, this time point was reached after just over half an hour. For the filter materials V1, L2, and V2, the increase in pressure loss occurred after more than an hour. For the filter material V3, the increase occurred after nearly two hours, and the filter material L3 had a particularly long service life, with the pressure loss increasing after more than two hours.

[0095] The roughness values of different filter materials are summarized in Table 2 below:

[0096]

[0097]

[0098] Table 2

[0099] The above measurement values prove that when the average roughness value Ra of the surface of the porous body 17 is greater than 15 μm, especially when it is greater than 17 μm, particularly good filtration effects can be achieved with a long service life. Therefore, it has been proven that a slightly higher value of the average roughness value Ra is more advantageous than an average roughness value Ra lower than the above value.

[0100] Figure 6a Shows the amount of water treated (Y-axis) and the pore size at the bubble point (X-axis) obtained from the measurement results. The amount of water treated refers to the total amount of water filtered through the corresponding filters L1, L2, and L3 until the pressure loss limit is reached. It is clearly shown by this graph that the pore size helps to increase the service life of the filter material. On the other hand, the pore size cannot be increased arbitrarily, otherwise it will affect the filtration effect.

[0101] Figure 7 Figure 7 schematically shows a cross-section of the first filter 8. This cross-section includes a sheet-like structure 80 composed of fibers 81, 82, and filter openings 83 are formed between these fibers. The fibers 81, 82 are arranged crosswise in a fibrous fabric. The first filter constitutes a surface filter, in which particles are separated as impurities at the surface of the first filter 8.

[0102] The filter openings 83 can have an opening width between 20 μm and 50 μm, preferably 30 μm.

[0103] Figure 8 shows a cross-section of the support 6. The longitudinal partitions 16 of the support and the channels 14 arranged between these longitudinal partitions can be clearly seen. The first filter 8 is arranged on the inner side of the support 6. The second filter 9 is arranged on the outer side of the support 6.

Claims

1. A filter device for a liquid medium, comprising a hollow support body (6) having a channel (14) for the liquid medium, wherein the hollow support body (6) is assigned a first filter (8), wherein the first filter (8) is designed as a surface filter, wherein the filter device has a backwashing device (11) in order to remove impurities from the first filter (8), characterized in that The support body (6) is assigned a second filter (9), wherein the second filter (9) is designed as a depth filter and wherein the second filter has a porous body (17) made of a sintered plastic material.

2. The filtering device according to claim 1, characterized in that: One of the first filter (8) and the second filter (9) is arranged at the inner side of the hollow support body (6), and the other of the first filter (8) and the second filter (9) is arranged at the outer side of the hollow support body (6).

3. The filtering device according to claim 1 or 2, characterized in that: The average pore size of the porous body (17) is between 10 μm and 30 μm.

4. The filtering device according to claim 1 or 2, characterized in that: The porosity of the porous body (17) is between 40% and 60%.

5. The filtering device according to claim 1 or 2, characterized in that: In the bubble pressure test, the bubble point is reached when the pressure difference at the porous body is between 0.003 bar and 0.005 bar.

6. The filtering device according to claim 1 or 2, characterized in that: The porous body (17) has a surface which, in at least a portion, has an average roughness value Ra greater than 15 μm.

7. The filtering device according to claim 1 or 2, characterized in that: The second filter (9) is cylindrical and has a cylindrical surface.

8. The filtering device according to claim 7, characterized in that: The cylindrical surface of the second filter has a material thickness of between 1 mm and 5 mm.

9. The filtering device according to claim 1 or 2, characterized in that: The filter device is configured such that during operation, fluid first flows through the first filter (8) and then through the second filter (9).

10. The filtering device according to claim 1 or 2, characterized in that: The first filter (8) has a filter opening (83) having an opening width greater than 20 μm.

11. The filtering device according to claim 1 or 2, characterized in that: The first filter (8) comprises a sheet-like structure having fibers (81, 82), wherein channels are formed between the fibers.

12. The filtering device according to claim 1 or 2, characterized in that: The first filter (8) is designed for coarse filtration, and the second filter (9) is designed for fine filtration.

13. The filtering device according to claim 1 or 2, characterized in that: The support body (6) comprises a cylindrical portion, wherein the channels (14) are arranged in rows in the cylindrical portion.

14. The filtering device according to claim 13, characterized in that: The first filter (8) is arranged at the inner side of the cylindrical portion, and the second filter (9) is arranged at the outer side of the cylindrical portion.

15. The filtering device according to claim 1 or 2, characterized in that: The filtering device has a pressure reducer.

16. The filtering device according to claim 1 or 2, characterized in that: The filtering device has a control unit that automatically operates the backwashing device.

17. The filtering device according to claim 16, characterized in that The control unit comprises a sensor device which detects a pressure difference at the first filter and / or the second filter and triggers a backwashing process when the measured pressure difference is higher than a set value of the pressure difference stored in the control unit.

18. The filtering device according to claim 4, characterized in that: The porous body (17) has a surface which, in at least a portion, has an average roughness value Ra greater than 15 μm.

19. The filtering device according to claim 3, characterized in that: The first filter (8) has a filter opening (83) having an opening width greater than 20 μm.

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