JP2005066549A - Double membrane ceramic filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic filter capable of sufficiently exhibiting a filtration function that is the inherent function of filtration layers even when it is applied with high filtration pressure. <P>SOLUTION: A double membrane ceramic filter has a monolithic support 31 having a plurality of parallel through holes 35 in the longitudinal direction, a tubular intermediate filtration layer 42 and a tubular filtration surface layer 43 laminated in this order on the outer peripheral surface of the support 31, and a tubular intermediate filtration layer 42' and a tubular filtration surface layer 43' laminated in this order on the inner peripheral surface of each of the above through holes. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic filter for separating solid particles dispersed in a liquid from the liquid, and more particularly to a ceramic filter for separating fine solid particles slightly dispersed in a liquid from the liquid. .

  Conventionally, a non-target structure ceramic filter for ultrafiltration and ultrafiltration, in which a porous ceramic filter layer having a pore size smaller than the pore size of the support is provided on the surface of a porous ceramic support. Ceramic filters were known. In addition, one or more porous ceramic filtering intermediate layers having a pore diameter smaller than the pore diameter of the support are provided on the surface of the porous ceramic support, and the filtration intermediate layer is further thinned. A non-target structure ceramic filter for ultrafiltration and a ceramic filter for ultrafiltration, which are provided by laminating a filter layer made of a porous ceramic having a pore size smaller than the pore size as the outermost layer on the filtration intermediate layer, are known. It was.

  Such a ceramic filter has a tube shape having one columnar space portion in the length direction (axial direction) or two or more channels (flow paths which are columnar space portions) in parallel in the length direction (axial direction). In the tube type, the filtration layer is tubular on either the inner side (the inner peripheral surface of the columnar space portion of the support) or the outer side (the outer peripheral surface of the support). It was formed by laminating as a filtration layer. In the monolith type, it was formed by laminating as a tubular filtration layer only on the inner side (inner peripheral surface of the columnar space portion of the support). Examples of the monolithic ceramic filter include those described in Patent Document 1 and Patent Document 2.

Japanese Patent Laid-Open No. 7-116480 JP-A-7-124428

  A tubular ceramic filter such as a tube type or monolith type in which a tubular filtration layer is laminated only on the inner peripheral surface of the columnar space of the support is filtered with high filtration pressure (for example, 8 MPa or more) with high efficiency. It is obtained when the liquid to be filtered is passed in the order from the filtration layer side to the support side (from the inside to the outside of the tubular ceramic filter) when used in the intended use (for example, cleaning of a glass substrate for liquid crystal). The number of particles in the filtrate was not smaller than a certain number, and there was a problem that the original filtration ability of the filtration layer was not exhibited.

  The objective of this invention is providing the ceramic filter which can fully exhibit the filtration performance which the filtration layer originally has also in the use used by high filtration pressure from one viewpoint. Moreover, the objective of this invention is the filtration which can use a ceramic filter so that the filtration layer of a ceramic filter may fully exhibit the original filtration performance also in the use used by high filtration pressure from one viewpoint. Is to provide a method.

  According to the first aspect of the present invention, in the first aspect, the ceramic filter having a filtration layer on the support, the liquid in the liquid to be filtered flows into the support inflow surface where the liquid flows into the support. One or more outflow surface side filtrations on a support outflow surface that has a surface side filtration layer and the liquid that has flowed into the support through the inflow surface side filtration layer flows out of the support. The above object can be achieved by the double membrane ceramic filter having layers.

  According to the present invention, in the second aspect, a ceramic filter having a filtration layer on a tube-type support having a columnar space in the length direction, wherein the liquid in the liquid to be filtered is the support. One or more inflow surface side filtration layers on the outer peripheral surface of the support flowing into the interior of the support, and the liquid that has flowed into the support through the inflow surface side filtration layer flows into the support. The above-mentioned object can be achieved by the double membrane ceramic filter having one or more outflow surface side filtration layers on the inner peripheral surface of the columnar space portion that flows out to the outside. According to the present invention, in the third aspect, the ceramic filter has a filtration layer on a monolithic support having two or more columnar spaces in parallel in the length direction. The liquid having one or more inflow surface side filtration layers on the outer peripheral surface of the support body into which the liquid flows into the support body, and flowing into the support body through the inflow surface side filtration layer The above object can be achieved by a double membrane ceramic filter having one or more outflow surface side filtration layers on the inner peripheral surface of the columnar space that flows out of the support.

  According to the present invention, in the fourth aspect, one or more layers of filtration are provided on each of the outer peripheral surface of the tube-shaped support body having one columnar space portion in the length direction and the inner peripheral surface of the columnar space portion. The above object can be achieved by the double membrane ceramic filter having layers. Further, according to the present invention, in the fifth aspect, at least one of the columnar space portions and the outer peripheral surface of the monolithic support body having two or more columnar space portions in parallel in the length direction. The above object can be achieved by the double membrane ceramic filter having one or more filtration layers on each inner peripheral surface of the space. When the support is of a tube type or a monolith type, the double membrane ceramic filter of the present invention has at least one of the outer peripheral surface and the end surface of the end of the support (that is, the tube type or the monolith type support 2 One end face of one end is a first outer peripheral face of the hook, the second outer peripheral face of the other end is a hook, and one end face of the two end faces existing on the support. A sealing layer that makes it difficult or impossible to pass the liquid in the liquid to be filtered can be provided on at least one of the first end face and the second end face that is the other end face.

  According to the present invention, in the sixth aspect, there is provided a filtration method for filtering a liquid to be filtered using the double membrane ceramic filter according to any one of the first to third aspects, wherein the inflow surface side filtration layer The above object can be achieved by a filtration method in which the liquid to be filtered is passed in the order of the support and the outflow surface side filtration layer. Moreover, according to the present invention, in a seventh aspect, there is provided a filtration method of filtering a liquid to be filtered using the double membrane ceramic filter according to any one of the fourth to fifth aspects, The above object can be achieved by a filtration method in which the filtration target liquid is passed in the order of the filtration layer on the outer circumferential surface, the support, and the filtration layer on the inner circumferential surface of the columnar space.

  The above-mentioned double membrane ceramic filter of the present invention sufficiently exhibits the filtration performance inherent to the filtration layer without peeling from the support of the filtration membrane or damage to the filter itself even in applications where the filtration pressure is high. Can do. In addition, according to the filtration method of the present invention, the filtration performance inherent to the filter layer of the ceramic filter can be sufficiently used in a high filtration pressure without peeling the filter membrane from the support or damaging the filter itself. A ceramic filter can be used as shown in FIG.

  The idea of the double membrane ceramic filter and the filtration method of the present invention is as follows. When using a tubular ceramic filter such as a tube type or monolith type in which a tubular filtration layer is laminated only on the inner peripheral surface of the columnar space of the support at a high filtration pressure (for example, 8 MPa or more), When the liquid to be filtered is passed in order from the filtration layer side to the support side (from the inside to the outside of the tubular ceramic filter), the number of particles in the obtained filtrate is as much as the filtration layer should be able to achieve originally. Will not get smaller. The inventor found that the cause is that the filtrate from which the solid particles are separated in the filtration layer is contaminated while passing through the support having a larger pore diameter than the filtration layer (the solid particles existing in the support). ). When the tubular ceramic filter is used at a high filtration pressure (for example, 8 MPa or more), the liquid to be filtered is passed in the order from the filtration layer side to the support side (from the inside to the outside of the tubular ceramic filter). The filter itself may be damaged.

  Therefore, when a tube-type or monolith-type ceramic filter in which a tubular filtration layer is laminated only on the inner peripheral surface of the columnar space portion of the support is used at a high filtration pressure (for example, 8 MPa or more), the filtration target An attempt was made to pass the liquid in the order from the support side to the filtration layer side (from the outside to the inside of the tubular ceramic filter). However, in this case, the problem that the filtration layer peels off from the support has occurred.

  Therefore, as a result of earnest research, by further providing a filtration layer on the outer peripheral surface of a tubular ceramic filter such as a tube type or monolith type in which a tubular filtration layer is laminated on the inner peripheral surface of the columnar space portion of the support. When using at a high filtration pressure (for example, 8 MPa or more), the filtration target liquid in the order of the filtration layer on the outer peripheral surface of the support, the support, and the filtration layer on the inner peripheral surface (from the outside to the inside of the tubular ceramic filter) The present invention has found that the filtration layer can exhibit the filtration performance that can be originally achieved without the problem that the filtration layer is peeled off from the support or the filter itself is damaged even if the filter is passed. It came to complete.

[Action]
The double membrane ceramic filter of the present invention according to the first to third aspects includes a support inflow surface through which liquid in the liquid to be filtered flows into the support and a support outflow surface through which the liquid flows out of the support. Since both have a filtration layer, the differential pressure (pressure difference) before and after the filtration layer can be reduced. Even if it is allowed to pass through, the separation of the filtration membrane can be prevented. Therefore, the outflow surface side filtration layer in the two-membrane ceramic filter of the present invention according to the first to third aspects separates the solid particles contained in the filtrate that has passed through the support without peeling from the support. Can do. Thus, since the liquid which finally passed through the filtration layer can be obtained as the filtrate, a filtrate obtained by separating and removing fine particles mixed in the support body when passing through the support body can be obtained.

  The double membrane ceramic filter of the present invention according to the fourth aspect has one layer on each of the outer peripheral surface of the tube-type support having one columnar space portion in the length direction and the inner peripheral surface of the columnar space portion. Since it has the above filtration layer, the differential pressure (pressure difference) before and after the filtration layer can be reduced. Therefore, the filtration layer on the outer peripheral surface of the support, the support, and the filtration layer on the inner peripheral surface of the columnar space portion Even if the liquid to be filtered is passed at a high filtration pressure in order, peeling of the filtration layer and damage to the filter itself can be prevented. Further, the double membrane ceramic filter of the present invention according to the fifth aspect includes an outer peripheral surface of a monolith type support body having two or more columnar space portions in parallel in a length direction and an inner peripheral surface of the columnar space portion. Since each has one or more filtration layers, the differential pressure (pressure difference) before and after the filtration layer can be reduced. Therefore, the filtration layer on the outer peripheral surface of the support, the support, and the inner periphery of the columnar space portion Even if the liquid to be filtered is passed at a high filtration pressure in the order of the filtration layer on the surface, peeling of the filtration layer and damage to the filter itself can be prevented.

  Therefore, the inner peripheral surface side filtration layer of the columnar space in the double membrane ceramic filter of the present invention from the fourth to fifth viewpoints is a solid contained in the filtrate that has passed through the support without peeling from the support. The particles can be separated. Thus, since the liquid which finally passed through the filtration layer can be obtained as the filtrate, a filtrate obtained by separating and removing fine particles mixed in the support body when passing through the support body can be obtained.

  Since the double membrane ceramic filter of the present invention has the inflow surface side filtration layer and the outflow surface side filtration layer, the differential pressure before and after the filtration layer is made smaller than when only one of these filtration layers is provided. Therefore, the filtration layer is difficult to peel from the support. This will be described in more detail.

  A conventional ceramic in which a tubular porous ceramic filter layer (pore diameter 0.2 μm) is laminated on the inner peripheral surface of a cylindrical space portion of a porous ceramic tube-type support (pore diameter 10 μm). A filter having a resistance ratio (depending on the pore diameter and thickness) of the support and the filtration layer of 1: 5 was filtered at a filtration pressure of 20 MPa. Since the differential pressure at the time is proportional to the resistance, the differential pressure before and after the support is 3.3 MPa, and the differential pressure before and after the filtration layer is 16.7 MPa.

  On the other hand, the ceramic filter of the present invention in which a tubular porous ceramic filtration layer (pore diameter 0.2 μm) is further laminated on the outer peripheral surface of the ceramic filter support, When the ratio of resistance (depending on pore diameter and thickness) of the filtration layer on the surface, the support and the filtration layer on the inner circumferential surface of the cylindrical space is 5: 1: 5, the filtration pressure is 20 MPa. Since the differential pressure when the liquid to be filtered flows is proportional to the resistance, the differential pressure before and after the filtration layer on the outer peripheral surface of the support becomes 9.0 MPa, and the pressure before and after the support is The differential pressure before and after the filtration layer on the inner peripheral surface becomes 9.0 MPa. As described above, in the case of the ceramic filter of the present invention, the differential pressure (pressure difference) before and after the filtration layer on the inner peripheral surface can be reduced to about ½ compared to the conventional ceramic filter. it can.

  A filtration method according to a sixth aspect is a filtration method for filtering a liquid to be filtered using the two-membrane ceramic filter according to the first to third aspects, and includes the inflow surface side filtration layer, the support, and the outflow. Since the liquid to be filtered is passed in the order of the surface-side filtration layer, even when filtering at a high filtration pressure, the outflow surface-side filtration layer is included in the filtrate that has passed through the support without peeling off from the support. Solid particles can be separated. The filtration method according to the seventh aspect is a filtration method for filtering the liquid to be filtered using the double membrane ceramic filter according to the fourth to fifth aspects, wherein the filtration layer on the outer peripheral surface of the support, the support In addition, since the liquid to be filtered is passed in the order of the filtration layer on the inner peripheral surface of the columnar space, the filtration layer on the inner peripheral surface of the columnar space even when filtered at a high filtration pressure (for example, 8 to 20 MPa) The solid particles contained in the filtrate that has passed through the support can be separated without peeling from the support and without further damaging the filter itself.

  When the double membrane ceramic filter of the present invention is a tubular ceramic filter such as a tube type or monolith type, the reason for flowing the liquid to be filtered from the outside of the filter to the inside (the filtration layer side of the inner circumferential surface of the columnar space) Has a higher compressive strength in the radially inner direction of the tubular ceramic filter than the tubular ceramic filter in the radially outward direction (usually 2 to 10 times the tensile strength), the filter of the present invention This is because it becomes possible to use at a higher filtration pressure.

[Support]
The support can be a porous ceramic support. The shape of the support is, for example, a tube-type support having one columnar space in the length direction, or a monolith type support having two or more columnar spaces in parallel in the length direction. be able to. When the support is made of porous ceramics, those having a pore diameter of about 1 to 100 μm (preferably 5 to 20 μm) can be used.

[Filtration layer]
The filtration layer can be a filtration layer made of porous ceramics, and can be provided by laminating one or more layers on the support. When the support is made of porous ceramic, the pore diameter of the porous ceramic filter layer is generally smaller than the pore diameter of the porous ceramic support. The pore diameter of the filtration layer provided as the outermost layer is preferably 0.01 to 1.0 μm (more preferably 0.05 to 0.2 μm).

  When two or more porous ceramic filter layers are stacked on a porous ceramic support, the filter layers may be stacked so that the pore diameter becomes smaller in order from the filter layer closer to the support. it can. The ratio of resistance between the inflow surface side filtration layer and the outflow surface side filtration layer when the liquid to be filtered passes can be 40/60 to 60/40 (preferably 45/55 to 55/45). The ratio of the thickness of the inflow surface side filtration layer and the outflow surface side filtration layer in the direction in which the liquid to be filtered passes can be 40/60 to 60/40 (preferably 45/55 to 55/45). .

[Seal layer]
When the support is of a tube type or a monolith type, a seal layer can be further provided on both ends of the support with or without a filtration layer. When sealing with the outer peripheral surface of the said both ends, a sealing layer can be provided in an outer peripheral surface, and when sealing with an end surface, a sealing layer can be provided in an end surface.

  The sealing layer can be formed of a material that does not penetrate the liquid to be filtered, and is a dense material made of, for example, glass or resin. As the material for the sealing layer, a material that can smooth the surface is preferably used. The surface of the sealing layer is preferably smooth. When the tube type or monolith type ceramic filter of the present invention is set (arranged) in a case (container), seal it with packing or O-ring at both ends, and concentrate the stock solution and filtrate during filtration. Isolate. At this time, by providing a sealing layer having a smooth surface, the sealing performance can be improved, and the number of particles in the filtrate can be reduced.

  The ceramic filter of the Example of this invention is demonstrated based on drawing. 1 is a schematic perspective view (partially omitted) of a monolithic ceramic filter according to a first embodiment of the present invention. FIG. 2 is a schematic sectional view of the ceramic filter of Example 1 in the radial direction. FIG. 3 is a schematic partial cross-sectional view of the ceramic filter of Example 1 in the length direction (perpendicular to the radial direction). FIG. 4 is a schematic enlarged cross-sectional view of a region A surrounded by an alternate long and short dash line in FIG.

[Example 1]
The ceramic filter of Example 1 is a monolith type filter having an outer diameter of 30 mm and having 19 parallel through holes (columnar spaces) 35 having an inner diameter of 4 mm. This filter has a monolithic support 31 made of porous ceramics having a pore diameter of 10 μm. A tubular filtration intermediate layer (thickness 40 μm) and a tubular filtration surface layer (thickness 40 μm) are laminated in this order on the outer surface (outer circumferential surface) of the support 31 and the inner surface (inner circumferential surface) of the through hole 35. Is formed. The pore diameter of the filtration surface layer is 0.2 μm. The pore diameter of the filtration intermediate layer is smaller than the pore diameter of the support 31 and larger than the pore diameter of the filtration surface layer.

  At both ends of the support 31, a tubular sealing layer 34 made of glass is formed on the outer peripheral surface from the end surface to 15 mm. On both end faces, formation of the intermediate layer (thickness 40 μm) and the filtration layer (thickness 40 μm) is optional. The ceramic filter of this example does not form an intermediate layer and a filtration layer on both end faces. In this case, it is generally necessary to form and seal a seal layer on both end faces, but in FIG. 3, the description of the seal layer to be formed on the end face is omitted.

  The material of the ceramic in the ceramic filter of the present embodiment is alumina ceramic. When the ceramic filter of this embodiment is in operation (in use), the liquid to be filtered is injected into the filter from the outer surface (outer peripheral surface) in the direction of the arrow 30 shown in FIG. The liquid to be filtered is fine with a double laminated filtration layer 32 formed on the outer peripheral surface of the support and a double laminated filtration layer 33 formed on the inner peripheral surface of the through hole 35 of the support 31. Solid particles are removed. The filtrate from which the fine solid particles have been removed flows out from the end of the through hole 35.

  As shown in FIGS. 3 to 4, the double laminated filtration layer 32 has a tubular filtration surface layer 43 laminated on the outer peripheral surface of a tubular filtration intermediate layer 42. The double laminated filtration layer 33 is formed by laminating a tubular filtration surface layer 43 ′ on the inner peripheral surface of a tubular filtration intermediate layer 42 ′.

  Using the monolithic ceramic filter of Example 1, the liquid to be filtered is supplied from the outer peripheral surface of the filter in the direction of the arrow 40 in FIG. The liquid to be filtered was passed in the order of the laminated filtration membranes on the surface (in the direction of the arrow 41 in FIG. 4). In this case, the number of particles of 0.2 μm or more in the obtained filtrate is 30 / ml, the membrane peeling filtration pressure (filtration pressure at which the filtration layer peels) is 20 MPa or more, and the damaged filtration pressure (filter The filtration pressure at which is damaged is 20 MPa or more.

[Example 2]
The ceramic filter of Example 2 is a tube type (cylindrical) filter having an outer diameter of 30 mm and having one through hole having an inner diameter of 10 mm. A tubular filtration intermediate layer (thickness 40 μm) and a tubular filtration surface layer (thickness 40 μm) are laminated in this order on the outer peripheral surface of the tube-type support and the inner peripheral surface of the through hole. The pore diameter of the filtration surface layer is 0.2 μm. The pore diameter of the filtration intermediate layer is smaller than the pore diameter of the support and larger than the pore diameter of the filtration surface layer.

[Comparative Example 1]
The filter of Comparative Example 1 is a monolithic ceramic filter similar to the ceramic filter of Example 1 except that no filter layer is provided on the outer peripheral surface of the support in the filter of Example 1. Using the monolithic ceramic filter of Comparative Example 1, the filtration target liquid was supplied from the outer peripheral surface of the filter, and the filtration target liquid was passed in the order of the support and the laminated filtration membrane on the inner peripheral surface of the through hole. In this case, the number of particles of 0.2 μm or more in the obtained filtrate is 35 / ml, the membrane peeling filtration pressure is 6 MPa, and the breakage filtration pressure is 20 MPa or more.

[Comparative Example 2]
Using the monolithic ceramic filter of Comparative Example 1, the filtration target liquid is supplied from the inner peripheral surface of the through hole of the filter, and the filtration target liquid is passed in the order of the laminated filtration membrane on the inner peripheral surface of the through hole and the support. It was. In this case, the number of particles of 0.2 μm or more in the obtained filtrate is 56 particles / ml, and the breakage filtration pressure is 8 MPa. In addition, since the filter itself was damaged before the membrane (filtration layer) peeled, the membrane peeling filtration pressure is unknown. In the damaged filter, the filtration layer does not peel from the support.

  In addition, the filtration object liquid used in Example 1 and Comparative Examples 1 and 2 is simple pure water (liquid obtained by passing tap water through a cartridge filter having a nominal filtration accuracy of 0.5 μm and an ion exchange resin cylinder). is there. Further, the internal pressure breaking strength at a static pressure of the monolith type ceramic filter having an outer diameter of 30 mm described in Example 1 is about 10 MPa, but there is an impact at the start of operation (at the start of supply of the liquid to be filtered to the filter). In some cases, it may break at 3-6 MPa. In the case of external pressure, no damage is caused even when a pressure difference of 20 MPa is applied.

FIG. 1 is a schematic perspective view of a ceramic filter according to an embodiment of the present invention. FIG. 2 is a schematic cross-sectional view in the radial direction of a ceramic filter according to an embodiment of the present invention. FIG. 3 is a schematic partial cross-sectional view in the length direction (perpendicular to the radial direction) of the ceramic filter of one embodiment of the present invention. FIG. 4 is a schematic enlarged cross-sectional view of a region A surrounded by an alternate long and short dash line in FIG.

Explanation of symbols

31 Support 32, 33 Laminated filtration layer 34 Seal layer 35 Through hole 42, 42 'Filtration intermediate layer 43, 43' Filtration surface layer

Claims (8)

  A ceramic filter having a filter layer on a support, the liquid in the liquid to be filtered having at least one inflow surface side filter layer on the support inflow surface into which the liquid flows into the support, and the inflow surface side A bi-membrane type ceramic comprising at least one outflow surface side filtration layer on a support outflow surface through which the liquid flowing through the filtration layer and flowing into the support outflows to the outside of the support filter.   A ceramic filter having a filtration layer on a tube-type support having a single columnar space in the length direction, wherein the liquid in the liquid to be filtered flows into the inside of the support. An inner peripheral surface of the columnar space portion that has one or more inflow surface side filtration layers, and the liquid that has flowed into the support body through the inflow surface side filtration layer flows out to the outside of the support body A double membrane ceramic filter characterized in that it has one or more outflow surface side filtration layers.   A ceramic filter having a filtration layer on a monolithic support having two or more columnar spaces in parallel in the length direction, wherein the liquid in the liquid to be filtered flows into the support. The columnar space portion has at least one inflow surface side filtration layer on an outer peripheral surface, and the liquid flowing into the support through the inflow surface side filtration layer flows out of the support. A double membrane ceramic filter comprising one or more outflow surface side filtration layers on an inner peripheral surface.   A double membrane ceramic characterized in that it has one or more filtration layers on each of an outer peripheral surface of a tube-type support having one columnar space portion in the length direction and an inner peripheral surface of the columnar space portion. filter.   One or more layers are provided on each of the outer peripheral surface of the monolithic support having two or more columnar space portions in parallel in the length direction and the inner peripheral surface of one or more columnar space portions of the columnar space portions. A double membrane ceramic filter comprising a filtration layer.   3. A seal layer that makes it difficult or impossible to pass a liquid in a liquid to be filtered is provided on at least one of an outer peripheral surface and an end surface of an end portion of the tube-type or monolith-type support. The double membrane ceramic filter according to any one of 5. A filtration method for filtering a liquid to be filtered using the double membrane ceramic filter according to any one of claims 1 to 3,
A filtration method, wherein the liquid to be filtered is passed in the order of the inflow surface side filtration layer, the support, and the outflow surface side filtration layer. A filtration method for filtering a liquid to be filtered using the double membrane ceramic filter according to any one of claims 4 to 6,
The filtration method characterized by allowing the liquid to be filtered to pass in the order of the filtration layer on the outer peripheral surface of the support, the support, and the filtration layer on the inner peripheral surface of the columnar space.

Images