Hydrophilic folding filter element and filter

Abstract

The utility model provides a hydrophilic folding filter element and a filter, the hydrophilic folding filter element comprises a central rod, a shell, an upper end cover and a lower end cover, and a folding filter medium layer is arranged in a cavity between the central rod and the shell; the folding type filtering medium layer is of a closed-loop structure formed by longitudinally sealing and welding a head folding unit and a tail folding unit after the filtering medium layer is folded around the central rod in the circumferential direction, and a welding seam is formed in the folding type filtering medium layer; the folding type filtering medium layer comprises a film layer and a supporting layer, the area, without the supporting layer, of the film layer located on the head folding unit and the tail folding unit is a welding face, the welding face of the head folding unit makes direct contact with the welding face of the tail folding unit, and a welding seam is located in the welding face. According to the hydrophilic folding filter element, the supporting layer is removed from the welding surface region of the hydrophilic folding filter element, so that the two ends of the film layer in the region are in direct contact in the form of the film layers, and the phenomenon that the supporting layer overflows under the dual action of pressure and high temperature in the longitudinal sealing welding process is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of filtration, in particular to a hydrophilic folded filter element and a filter. Background Art

[0002] Pleated filter element, also called pleated filter element, is a common filtering device with the advantages of high flux, high retention and low cost. Due to the high filtering accuracy and flow rate of the pleated filter element, it can effectively intercept tiny particles and colloidal debris, so the filtering efficiency is extremely high. The main materials of the pleated filter element are stainless steel wire mesh, sintered mesh, polypropylene, polytetrafluoroethylene, polyethersulfone, polyvinylidene fluoride, etc. This kind of filter element has a wide range of applications, large membrane filtration area, large dirt holding capacity and long service life. Overall, the filter element meets the filtering requirements of food and beverage processing, chemical, pharmaceutical and other industries, and is an indispensable component in the fluid processing process.

[0003] During the filtration process, the performance differences of the filter membrane itself will have different effects on the filtration effect. Some membranes prepared from polymer materials have excellent filtration capabilities and good chemical compatibility, but these materials are highly hydrophobic, which makes them unfavorable for the circulation and dispersion of the feed liquid during the filtration process, and the actual use area of ​​the filter membrane during the filtration process is also limited.

[0004] The Chinese patent document discloses "a microporous membrane filter element with an asymmetric membrane", and its announcement number is CN205760669U. The filter membrane used in the filter element of the utility model is a microporous membrane that has been sulfonated, which ensures that the filter membrane has uniform hydrophilicity and reduces the difficulty of wetting the filter membrane surface. The filter membrane has the characteristics of large flux and low resistance, so that the filter element using the filter membrane has ultra-high flow and ultra-strong dirt holding capacity. The folded filter element adopts a thermal welding method to make the connection between the center rod, the shell, the upper and lower end covers and the folded filter membrane firm and have good sealing performance. However, the folded filter element will be impacted by the feed liquid during use. The strength of the filter membrane itself is not enough. Generally, a support layer is set on both sides of the filter membrane to play a protective role. However, the support layer is generally a material with poor hydrophilicity. When the ends of the folded filter membrane are thermally welded together, there is a situation where the support layer melts and flows to the filter membrane surface outside the sealing area due to the excessively high welding temperature, so that this part of the filter membrane surface is covered, making this part of the filter membrane difficult to wet during the filtration process, and at the same time causing the effective filtration area of ​​the filter membrane to be reduced during use. Utility Model Content

[0005] In view of the shortcomings of the prior art mentioned above, the technical problem to be solved by the present invention is to overcome the problem in the prior art that when the head and tail folded units of the folded filter medium that are axially parallel are heat-welded together, the supporting layer will melt and flow to the filter membrane surface outside the sealing area (weld) due to the excessively high welding temperature, thereby covering part of the filter membrane surface outside the weld. During the filtration process, this part of the filter membrane is more difficult to wetting, resulting in a reduction in the effective filtration area of ​​the filter membrane during use. The purpose of the present invention is to provide a hydrophilic folded filter element and filter that can further enhance the wetting effect of the filter membrane and increase the actual use area of ​​the filter membrane while ensuring the original filtration performance of the filter membrane.

[0006] To achieve the above-mentioned purpose and other related purposes, the utility model is implemented by including the following technical solutions.

[0007] The utility model provides a hydrophilic pleated filter element, comprising a coaxially arranged center rod, an outer shell, and an upper end cover and a lower end cover arranged at the axial ends of the center rod and the outer shell, a folded filter medium layer is arranged in a cavity between the center rod and the outer shell, the folded filter medium layer is a closed-loop structure formed by longitudinally sealing and welding a first folding unit and a tail folding unit after the filter medium layer is folded circumferentially around the center rod, and a weld is formed on the folded filter medium layer during the longitudinal sealing welding; the folded filter medium layer comprises a membrane layer and a support layer arranged on both sides of the membrane layer, the area on the membrane layer of the first folding unit and the tail folding unit circumferentially of the folded filter medium layer where the support layer is not arranged is a welding surface, the welding surfaces of the first folding unit and the tail folding unit can be in direct contact with each other, and the weld is located in the welding surface.

[0008] Wherein, the folded filter medium layer includes a plurality of folding units, one end of the folding unit abuts against the inner wall of the shell, and the other end abuts against the outer wall of the center rod, and the folding unit refers to an axial plane.

[0009] Among them, the welding surface refers to the area on the membrane layer of the first and last folding units of the folded filter medium layer in the circumferential direction where no support layer is provided. Therefore, the welding surfaces of the first folding unit and the last folding unit can be in direct contact with each other, and there is no support layer between the welding surfaces. In the form of contact between the membrane layers, the two ends of the membrane layer can be directly contacted and welded as a whole during the longitudinal sealing welding process. Since all or part of the welding surface is selected for longitudinal seam welding, the phenomenon of overflow of the support layer under the dual effects of pressure and high temperature in the longitudinal sealing welding process is effectively avoided, the hydrophilicity of the filter medium layer on the welding surface is improved, and the resistance of the filter pores of the feed liquid is reduced. Under the premise of ensuring the original filtering performance of the membrane layer, the hydrophilic effect of the filter element as a whole is further improved, thereby further improving the wetting effect of the membrane layer during actual use and increasing the actual use area of ​​the membrane layer. In addition, the direct contact between the membrane layers makes it only necessary to ensure that the sealing between the membrane layers is completed during the longitudinal sealing process to achieve the sealing of the filter element, and no excessive weld length is required. At this time, the filtration area will increase, and since the properties of the membrane layers are exactly the same, the sealing strength and sealing reliability are greatly enhanced.

[0010] Preferably, the welding surfaces between the two folds of the first and last folding units do not completely correspond to each other.

[0011] During longitudinal sealing, the first folded filter medium layer and part of the last folded filter medium layer are completely melted under the dual effects of pressure and high temperature, and are cooled and pressed to form a new integrated filter medium layer. The completely melted area is called a weld. During this process, the material between the two folds will produce a certain amount of overflow under the dual effects of pressure and high temperature. These overflows will have a certain impact on the filter medium layers of the adjacent folds. The overflows will fill the space between the support layer and the membrane layer, which will not only block the filter holes of the membrane layer, but also increase the resistance of the feed liquid passing through the support layer into the filter holes of the membrane layer. At the same time, the hydrophilicity of the support material is generally much lower than that of the membrane layer. The overflow will greatly reduce the hydrophilicity of the membrane layer, which is not conducive to the circulation and dispersion of the feed liquid during the filtration process, and the actual use area of ​​the membrane layer during the filtration process is also limited.

[0012] Since the longitudinal sealing welding process needs to be carried out under high temperature conditions, the properties of the membrane layer around the welding surface and even the folds next to it may change under high temperature, resulting in insufficient or even disappearance of the filtering capacity, which greatly reduces the effective filtering area of ​​the filter element. The utility model effectively solves the above problem by adjusting the support layer on both sides of the membrane layer. During longitudinal sealing welding, since the heat transfer temperature will decay inward, the temperature on the inside is the lowest, so the support layer on the outside can withstand a higher temperature, protect the membrane layer, and ensure the hydrophilicity and effective filtering area of ​​the membrane layer.

[0013] Optionally, there are partial areas on both sides of the membrane layer of the first fold filter unit and / or the tail fold filter unit that are not covered by the support layer.

[0014] Preferably, the support layer is a non-woven fabric or a screen, and the support layer is consistent with the membrane layer in axial length, thereby ensuring a good sealing effect between the axial ends of the filter medium layer and the filter element end caps.

[0015] Preferably, the ratio of the radial length k of the welding surface to the leg length d is 50-100%. The leg length d is the length of a single folding unit.

[0016] Preferably, the leg length d is 8-16 mm, and the radial length k of the welding surface is 6-14 mm. The k value must be greater than 6 mm to ensure that the inner support layer does not affect the connection between the membrane layers during longitudinal sealing. The k value is less than 14 mm to facilitate the removal of the inner support layer after the filter medium layer is completely folded.

[0017] The radial lengths of the welding surfaces of the first and the last folding units may be different.

[0018] Preferably, the length w of the weld along the radial direction of the center rod accounts for 12.5-75% of the leg length d. After removing the inner support layer, it is only necessary to ensure the seal between the membrane layers during longitudinal sealing welding, so there is no need for an excessively large weld length. At this time, the filtration area will increase. Therefore, the value of the length w of the weld along the radial direction of the center rod of the present application is set to be lower than the w value of the normal filter element, but it cannot be too small. When w is too small, there is a hidden danger of insufficient sealing strength due to the short length of the weld along the circumference of the center rod. When w is too large, the sealing area is too large to reduce the filtration area. At the same time, there is too much molten overflow generated by welding, which fills the space between the support layer and the membrane layer, which will not only block the filter holes of the membrane layer, but also increase the resistance of the feed liquid passing through the support layer into the filter holes of the membrane layer, affecting the filtration efficiency.

[0019] Preferably, the length w of the weld along the radial direction of the center rod is 2-6 mm.

[0020] Preferably, along the axial direction of the central rod, the axial lengths of the membrane layer, the support layer, the central rod and the outer shell are consistent.

[0021] Preferably, the membrane layer comprises a first filter membrane and a second filter membrane which are stacked.

[0022] Preferably, the first filter membrane and / or the second filter membrane is selected from any one of a polypropylene filter membrane, a polyethersulfone filter membrane, a polyvinylidene fluoride filter membrane, a polytetrafluoroethylene filter membrane, a nylon filter membrane and a regenerated cellulose filter membrane.

[0023] Preferably, in the axial direction of the center rod, the length of the membrane layer and the support layer is consistent with the axial length of the center rod and the shell, so that the folded filter medium layer is folded around the circumference of the center rod to form a three-dimensional structure with multiple folds.

[0024] Preferably, the elastic modulus of the support layer is greater than 100 Mpa, so that during the connection process between the filter medium layer and the end cover, the support layers located on both sides of the membrane layer can ensure that the filter medium layer always remains upright, thereby effectively protecting the membrane layer.

[0025] Preferably, the friction coefficient of the support layer is 0.05~0.4. The support layer must ensure a sufficient friction coefficient so that after folding is completed, especially during the longitudinal sealing welding process of the filter medium layer of the head and tail folding units, it can be ensured that there will be no axial relative displacement between the first support layer and the second support layer and the membrane layer.

[0026] Preferably, the support layers on the liquid inlet and / or liquid outlet sides of the membrane layer can be set to be multiple layers. The support layer farthest from the membrane layer side is made of a material with higher strength to play a shaping role, and the support layer closest to the membrane layer side is made of a material with a smooth surface to reduce damage to the filter membrane and protect the filter membrane.

[0027] The utility model also provides a filter including the hydrophilic folded filter element. The filter using the hydrophilic folded filter element has good flow dispersion of the feed liquid during the filtration process, a large actual use area of ​​the filter membrane during the filtration process, and is not easy to be clogged. As described above, the utility model has the following beneficial effects:

[0028] (1) By removing the support layer from the welding surface of the hydrophilic folded filter element, the two ends of the membrane layer in this area are directly in contact with each other in the form of membrane layer and membrane layer. The two ends of the membrane layer can be directly in contact and welded as a whole during the sealing welding process, avoiding the phenomenon of overflow of the support layer under the dual effects of pressure and high temperature in the longitudinal sealing welding process, improving the hydrophilicity of the filter medium layer on the welding surface, reducing the filter pore resistance of the feed liquid, and improving the overall hydrophilic effect of the filter element while ensuring the original filtering performance of the membrane layer. The wetting effect of the membrane layer is improved and the actual use area of ​​the membrane layer is increased;

[0029] (2) In the longitudinal sealing process, the sealing of the filter element can be achieved by only ensuring that the sealing between the membrane layers is completed, and there is no need for an excessively large weld length. In this case, the filtration area will be increased. Since the properties of the membrane layers are exactly the same, the sealing strength and sealing reliability are greatly enhanced;

[0030] (3) The filter using the hydrophilic folded filter element has good flow dispersion of the feed liquid during the filtration process, the actual use area of ​​the filter membrane is large during the filtration process, and it is not easy to be blocked. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Shown is a schematic diagram of the structure of the hydrophilic pleated filter element of Example 1.

[0032] Figure 2 Display as Figure 1 Cross-sectional view along the AA direction.

[0033] Figure 3 Shown is an exploded view of the structure of a pleated filter media layer.

[0034] Figure 4 Display as Figure 3 Top view of the .

[0035] Figure 5 Shown is a cross-sectional view of the weld surface in Example 1.

[0036] Figure 6 Shown is a cross-sectional view of the weld surface in Example 2.

[0037] Figure 7 Shown is a cross-sectional view of the weld surface in Example 3.

[0038] Figure 8 Shown is a cross-sectional view of the weld surface in Example 4.

[0039] Explanation of the accompanying drawings: 1. center rod; 2. outer shell; 3. upper end cover; 4. lower end cover; 5. folded filter medium layer; 6. first support layer; 7. membrane layer; 71. first filter membrane; 72. second filter membrane; 8. second support layer; D. weld. DETAILED DESCRIPTION

[0040] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0041] See also Figures 1 to 8 It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings in this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change in the proportion relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the utility model without affecting the effects and purposes that can be achieved by the utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the utility model without substantially changing the technical content.

[0042] Example 1

[0043] like Figure 1 and Figure 2As shown, the embodiment of the present application provides a hydrophilic pleated filter element, comprising a coaxially arranged central rod 1, a shell 2, and an upper end cover 3 and a lower end cover 4 arranged at both ends of the central rod and the shell, and a pleated filter medium layer 5 is arranged in the cavity between the central rod and the shell, as shown in FIG. Figure 2 As shown, the folded filter medium layer is a closed loop structure formed by longitudinally sealing and welding the first folded unit and the last folded unit after the filter medium layer is circumferentially folded around the center rod; the folded filter medium layer includes a plurality of folded units, one end of the folded unit abuts against the inner wall of the shell, and the other end abuts against the outer wall of the center rod, and each folded unit is an axial plane; a weld D is formed when the folded filter medium layer is longitudinally sealed and welded; as shown Figure 3 and Figure 4 As shown, the pleated filter medium layer includes a membrane layer and support layers arranged on both sides of the membrane layer. The area on the membrane layer of the first folding unit and the last folding unit in the circumferential direction of the pleated filter medium layer where the support layer is not arranged is the welding surface. The welding surfaces of the first folding unit and the last folding unit can directly contact each other. The weld is located in the welding surface. The filter medium layer includes a first support layer 6, a membrane layer 7 and a second support layer 8 from the outside to the inside. Figure 5 As shown, the first support layer does not cover the welding surface of the pleated filter medium layer, wherein the welding surface refers to Figure 4 The axial extension area of ​​the radial length k marked on the middle film layer 7, k is specifically the distance between the circumferential end of the support layer 6 not covering the welding surface and the circumferential end of the film layer 7 closest to it, and the weld D is located on the welding surface, wherein Figure 4 It is only to illustrate the positional relationship between the support layer 6, the membrane layer 7, and the support layer 8, and is not used to indicate the actual length relationship between the three. In practice, the leg lengths of the three in the same folded filter medium layer are not much different. In the folded filter medium layer 5, the first support layer 6 located at the first folding unit and the last folding unit is removed so that the two ends of the membrane layer in the weld D are in contact. The membrane layer is a single-layer structure, using a polypropylene filter membrane. The elastic modulus of the first support layer and the second support layer is greater than 100Mpa, and the friction coefficient of the first support layer and the second support layer is 0.05~0.4; the material of the first support layer and the second support layer are both non-woven fabrics.

[0044] like Figure 4 and Figure 5 As shown, the leg length is 8-16 mm, and the length w of the weld D along the radial direction of the center rod is 2-6 mm. The distance k between the circumferential end of the first support layer and the circumferential end of the membrane layer is 6-14 mm, and the ratio of the distance k between the circumferential end of the first support layer and the circumferential end of the membrane layer to the leg length d is 50-100%. The length w of the weld surface along the radial direction of the center rod accounts for 12.5-75% of the leg length d.

[0045] Example 2

[0046] like Figure 6 As shown, the difference between Example 2 and Example 1 is that, in the folded filter medium layer 5, the second support layer located in the first folding unit is removed, and the distance between the circumferential end of the second support layer and the circumferential end of the membrane layer accounts for 50-100% of the length d of a single folding unit, and the rest of the structure is exactly the same.

[0047] Example 3

[0048] like Figure 7 As shown, the difference between Example 3 and Example 1 is that in the folded filter medium layer 5, the second support layer located at the tail folding unit is removed, and the distance between the circumferential end of the second support layer and the circumferential end of the membrane layer accounts for 50-100% of the leg length d, and the rest of the structure is exactly the same.

[0049] Example 4

[0050] like Figure 8 As shown, the difference between Example 4 and Example 1 is that in the folded filter medium layer 5, the membrane layer adopts a double-layer structure, including a first filter membrane 71 and a second filter membrane 72 that are stacked, and the rest of the structure is exactly the same.

[0051] Example 5

[0052] The difference between Example 5 and Example 1 is that, in the folded filter medium layer 5, the membrane layer and the support layers on both sides of the membrane layer both adopt a double-layer structure, and the strength of the support layer located on the side far from the membrane layer in the single-sided support layer is higher than the strength of the support layer located on the side close to the membrane layer, and the surface of the support layer located on the side close to the membrane layer is a smooth surface; the rest of the structure is exactly the same.

[0053] In summary, the utility model removes the support layer in the welding area of ​​the hydrophilic folded filter element, so that the two ends of the membrane layer in the area are directly in contact in the form of membrane layer and membrane layer. The two ends of the membrane layer can be directly in contact and welded as a whole during the sealing welding process, avoiding the phenomenon of overflow of the support layer under the dual effects of pressure and high temperature in the longitudinal sealing welding process, improving the hydrophilicity of the filter medium layer on the welding surface, reducing the resistance of the feed liquid filter pores, and improving the overall hydrophilic effect of the filter element while ensuring the original filtering performance of the membrane layer. Improve the wetting effect on the membrane layer and increase the actual use area of ​​the membrane layer; the surface of the membrane layer in direct contact with the membrane layer is the welding surface, so that in the longitudinal sealing process, it is only necessary to ensure that the sealing between the membrane layers is completed to achieve the sealing of the filter element, and no excessive weld length is required. At this time, the filtration area will increase, and because the properties of the membrane layers are exactly the same, the sealing strength and sealing reliability are greatly enhanced. Therefore, the utility model effectively overcomes the various shortcomings of the prior art and has a high industrial utilization value.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims

1. A hydrophilic pleated filter element, characterized in that: The invention comprises a coaxially arranged center rod (1), an outer shell (2), and an upper end cover (3) and a lower end cover (4) arranged at the axial ends of the center rod and the outer shell. A folded filter medium layer (5) is arranged in the cavity between the center rod and the outer shell. The folded filter medium layer (5) is a closed-loop structure formed by longitudinally welding a first folding unit and a last folding unit after the filter medium layer is folded circumferentially around the center rod. A weld (D) is formed on the folded filter medium layer during longitudinal welding. The folded filter medium layer (5) comprises a membrane layer and a support layer arranged on both sides of the membrane layer. The area on the membrane layer of the first folding unit and the last folding unit of the folded filter medium layer in the circumferential direction where the support layer is not arranged is a welding surface. The welding surfaces of the first folding unit and the last folding unit can be in direct contact with each other, and the weld is located within the welding surface.

2. The hydrophilic pleated filter element according to claim 1, characterized in that: The ratio of the radial length k of the welding surface to the leg length d is 50-100%.

3. The hydrophilic pleated filter element according to claim 2, characterized in that: The leg length d is 8 to 16 mm, and the radial length k of the welding surface is 6 to 14 mm.

4. The hydrophilic pleated filter element according to claim 1, characterized in that: The length w of the weld along the radial direction of the central rod accounts for 12.5-75% of the leg length d.

5. The hydrophilic pleated filter element according to claim 4, characterized in that: The length w of the weld along the radial direction of the center rod is 2 to 6 mm.

6. The hydrophilic pleated filter element according to claim 1, characterized in that: Along the axial direction of the central rod, the axial lengths of the membrane layer, the support layer, the central rod and the shell are consistent.

7. The hydrophilic pleated filter element according to claim 1, characterized in that: The membrane layer comprises a first filter membrane (71) and a second filter membrane (72) which are stacked, and the first filter membrane and / or the second filter membrane are selected from any one of a polypropylene filter membrane, a polyethersulfone filter membrane, a polyvinylidene fluoride filter membrane, a polytetrafluoroethylene filter membrane, a nylon filter membrane and a regenerated cellulose filter membrane.

8. The hydrophilic pleated filter element according to claim 1, characterized in that: The elastic modulus of the support layer is greater than 100 MPa, and the friction coefficient of the support layer is 0.05-0.

4.

9. The hydrophilic pleated filter element according to claim 1, characterized in that: There are partial areas on both sides of the membrane layer of the first folding unit and / or the last folding unit that are not covered by the supporting layer.

10. A filter, characterized in that: It comprises the hydrophilic pleated filter element as described in any one of claims 1 to 9.

Images