JPS63236509A - Ceramic filter - Google Patents

Abstract

PURPOSE:To make effective area larger and collect and remove effectively floating fine articles contained in high temperature and high pressure fluid, particularly liquid, by using plate-shaped elements in a ceramic filter. CONSTITUTION:Plate-shaped, for example, disc-shaped filter elements 1 each having a main body 12 constituted of a ceramic porous material and a ceramic film 13 having an average pore diameter smaller than that of the main body 12 on the fluid inflowing side face of the main body 12 are used for a ceramic filter. The element 1 has an opening in the center, and the area around the opening is thickener than other sections, which maintains the interval between adjacent elements 1 at a given distance or more, secures a flow channel of raw liquid sufficiently and makes filter area work effectively. As a result, a large effective area can be secured and floating fine particles contained in high temperature and high pressure fluid, particularly in liquid, can be collected and removed effectively.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a ceramic filter composed of a ceramic plate element for efficiently capturing and removing suspended particulates contained in a fluid, particularly a high-temperature, high-pressure fluid. It is related to.

[Conventional technology and its problems]

Ceramic filters generally have the following characteristics.

+1) It has extremely excellent corrosion resistance against all kinds of corrosive liquids.

(2) It has high heat resistance and can be used at high temperatures without being thermally deformed, softened, or oxidized.

(3) A filter with a uniform pore distribution and any pore size can be produced depending on the particle size of the ceramic powder used as a raw material, molding conditions, firing conditions, etc.

(4) No eluate is generated and there is no contamination of the liquid.

Taking advantage of this % property, the chemical industry, food,
It is widely used in fields such as medicine, metal industry, and radioactive waste treatment.

The structure of elements constituting conventional ceramic filters is mostly cylindrical as shown by the reference numeral 21 in FIG. 6, and modules using a plurality of these elements are common.

Note that the arrow indicates the direction in which the liquid flows.

However, in the case of a cylindrical element, the effective filtration surface is only on the fluid inlet side, ie, either the inner surface or the outer surface of the cylinder. Furthermore, there are limits to the outer diameter of the elements that can be used, either from the viewpoint of strength or from the viewpoint of preventing damage during assembly due to brittleness.

In other words, the dimensions of the elements of the ceramic filters that are in practical use are approximately 1,000 mm in length and 1,000 mm in outer diameter.
The limit is about 0m.

For these reasons, it has been difficult to increase the effective area of ceramic filters using cylindrical elements.

Therefore, in order to increase the effective filtration area, measures such as using a honeycomb structure for the filter element are taken.

However, in the case of a honeycomb structure, in order to effectively utilize its filtration area, it is necessary to close one of the through holes with a ceramic material with a sealing material 17 as shown in FIG.
etc., and the structure of the element 22 is complicated. In this case, when used under high temperature conditions, it is necessary to use the same material or materials with the same coefficient of thermal expansion for the honeycomb structure and the sealing material.

On the other hand, ceramic filters that effectively utilize the transient area without using a sealant have already been put into practical use. The f-filtration method of this filter employs the Cross 70 one-way method, but this method has a major drawback in that a large amount of concentrated liquid must be treated by other methods or discarded.

[Means for solving problems]

The present invention is a ceramic filter composed of a plurality of plate-like elements made of a ceramic porous body and having an opening in the center, in which both sides of the element and an end face different from the cut face when opening the element are fluidized. The element is configured such that the surface cut at the time of opening becomes the fluid outflow side, and the element has a base body made of porous ceramic material and a surface of the base body on the fluid inflow side that has an average pore diameter smaller than that of the base body. This is a ceramic filter characterized by having a ceramic thin film having the following characteristics.

The present invention was made in view of the problems in the prior art described above, and is effective by using a plate-like nilemara, which has a simple structure, in a ceramic filter. In particular, we have completed a ceramic filter that can efficiently capture and remove suspended particles contained in liquids.

The pore size of the matrix of the plate element made of ceramics can be controlled by known methods such as changing the size of the particles used when forming the filter or changing the particle size distribution of the zero particles. In addition, in order to form a thin film with a small average pore diameter on a matrix, a film with a small pore diameter can be formed by attaching ceramic fine particles, ceramic fibers, or ceramic whiskers to the surface of the matrix.

When fibers or whiskers are used as the material for forming the thin film t', there is an advantage that the porosity of the thin film can be increased compared to when fine particles are used.

Furthermore, when firing is performed after applying fine particles, fibers, or whiskers to the surface of the matrix, a film with fine pores can be obtained by firing at a temperature lower than the temperature at which the matrix was fired. This is because the crystal growth of fine particles changes depending on the firing temperature.

In particular, when silicon carbide fine powder and whiskers are used, the size of the pores can be easily controlled by changing the firing conditions.

Next, one embodiment of the present invention will be explained in detail based on the drawings. FIG. 1 is a diagram for explaining the case where the ceramic filter of the present invention is used as a high temperature/high pressure liquid filter.

In FIG. 1, 1 is a disc-shaped filter element,
It has an opening in the center, and the area around the opening is thicker than the other parts.

This thickness makes it possible to maintain a certain distance between adjacent elements, secure a sufficient flow path for the stock solution, and allow the filtration area to work effectively.Also, by making this part thicker, the strength is increased. It's also effective. In addition, if the thickness of the element 1 is strong enough to withstand the force of the coil spring 9 when used under high temperature and high pressure conditions, the thickness of the element 1 is constant. It is also possible to insert a spacer ring to secure the flow path.

Element 1 has f-filtration holes on both sides, and the stock solution introduced from stock solution port 2 is filtered from both sides to the opening in the center, and then passes through the opening in support material 8 to the P solution. Exit 3
It flows out as a purified liquid.

In the illustrated example, a pipe with an opening is used as the support member 8, but the support member 8 may be any material that can easily support the element 1 and has an opening, for example, a plurality of round rods. 0 FIG. 2 is an enlarged view of the part A in FIG. is thin film 1
It has an average pore diameter sufficiently larger than 5. By doing this, the filtration pressure loss of the matrix can be reduced, and the filtration pressure loss of one element is dominated by the filtration pressure loss due to the thin film. As a result, the f overvelocity on the element surface is controlled by the structure of the thin film and is almost unaffected by the distance from the center of the plate-like element (fluid outflow side), making it possible to ensure a uniform flow velocity over the entire filtration surface. . In other words, all the filtering surfaces of the plate-like element act as a uniform effective filtering surface.

In addition, the pressure acting on the front and back surfaces of the element 10 is the same, and since the matrix is made of porous ceramic material and is not hollow, it has sufficient pressure resistance as a filter, so the plate thickness should be made sufficiently small. Can be done.

Therefore, many elements 1f can be stacked and used in a small space.

In this way, by using the module of the present invention,
A sufficiently large filtration area can be secured compared to conventionally used cylindrical elements.

The shell 5, cover 6, . 7 and support pipe 8
The element 1 is made of a steel plate such as stainless steel, for example, and has a higher coefficient of thermal expansion than the element 1 made of a ceramic porous body, and its elongation due to heat is different under high temperature conditions. Therefore, by using the coil spring 9t, the element 1 is always pressed down with a constant force, and the structure is such that the stock solution does not leak to the f-liquid side. The material of the coil spring 9 is ceramics, stainless steel, or the like. Note that if the thermal expansion can be absorbed by the packing inserted between the elements 1, the coil spring is not necessary.

In FIG. 1, numeral 4 denotes a discharge port for discharging floating particles separated during backwashing, 10 a furnace packing, and 11 a fixing bolt.

The pore size of the ceramic porous body constituting the ceramic filter of the present invention is determined by the particle size of suspended particles contained in the stock solution. When used as a normal filtration filter or a filtration filter, the pore diameter of the thin film 13 is α1 to 5 μm, the film thickness is 5 to 200 μm, and the pore diameter of the matrix 12 is α1 to 5 μm.
It is important to make the pores sufficiently larger than the thin film 13 to be used, although the pore diameter of the pores in the pores 6 varies, and is usually 1 to 600 μm, and the porosity is preferably 25 or more by volume. Especially mother body 1
In order to suppress the filtration pressure loss due to 2 to a sufficiently small level, the base body 12
More preferably, the porosity is 40 or more.

In this way, by using the module of the present invention,
Compared to conventionally used cylindrical elements, a sufficiently wider filtration area can be secured, and the plate-shaped element has a thin film added to its surface, making it possible to avoid the use of conventional pre-coated filters. For example, when removing crud in brackish water circulation systems in power plants or removing suspended matter in the food industry, ceramics can be used to efficiently remove suspended matter under high temperature and high pressure conditions without pre-coating. I was able to provide a filter.

This filter element can be easily regenerated by backwashing during normal operation.

This is because the pressure loss due to the thin film 13 is more dominant than that of the base body 12, so that the pressure used for backwashing, nitrous gas, or backwash water acts uniformly on the filtration surface.

Furthermore, if regeneration becomes impossible by backwashing, regeneration is possible by ultrasonic cleaning in hydrochloric acid or hydrofluoric acid.

The ceramic filter element is preferably a porous body mainly made of one or more selected from silicon carbide, cane nitride, alumina, zirconia, magnesia, sialon, cordierite, mullite, and titanium oxide.

This is because these materials have excellent corrosion resistance and high mechanical strength.

Furthermore, the present inventors have anticipated an element having a structure in which the thickness of the plate-like element gradually decreases from the opening toward the tip. This structure ensures a sufficient flow path for the stock solution and allows the filtration surface to be effective.
Furthermore, by keeping the flow rate of the fluid flowing through the porous ceramic body uniform and low without increasing it toward the center, pressure loss can be kept even lower.

Further, as a means to further increase the surface area of the plate-like element, it is also possible to add a wave shape or an uneven shape to at least one side.

Next, the present invention will be specifically explained.

Outer diameter 220m, thickness of 2 filters 3cm, center opening diameter 90m
-, a disk-shaped element as shown in FIG. 1 was used, which had a width of 5111 IVC and a thickness of 4 m along the opening. The packing used had a thickness of 0.5 m. For example, if 414 disk-shaped elements are stacked, the axial length of the combined elements is (4+15) x 414 = 1
With a length of 863 mm, a very large effective filtration area of 26 m2 could be obtained.

Next, a method for producing a plate-like element constituting this ceramic filter will be specifically explained.0 As a starting material, fine silicon carbide powder with an average particle size α of 28 μm was used. The silicon carbide fine powder contains 94.6% by weight of β-type crystals, υ, α39% by weight of free carbon, [117
3% by weight of iron and 3% by weight of cL0
of aluminum.

5 parts by weight of polyvinyl alcohol and 500 parts by weight of water were blended with 100 parts by weight of the silicon carbide fine powder, mixed in a ball mill for 5 hours, and then dried.

An appropriate amount of this dry mixture was taken and made into granules with a diameter of approximately α1°, and then rubber press molded using a metal tearing die at a pressure of 500 hours/- to a thickness of approximately 5 mm as shown in 1 in Figure 1.
The obtained molded body processed into the shape of a disc-shaped filter element of 111I+ was charged into a graphite crucible and fired in a 1 atm argon gas atmosphere using a Tammann type firing furnace.

Firing was performed by increasing the temperature to 2200°C at a rate of 2.5°C/min.
This temperature was maintained for 6 hours.

The obtained sintered body has an average pore diameter of 160 μm and a porosity of 4.
It was a silicon carbide porous body consisting of plate-like crystals with a capacity of 8.

Next, 5% polyvinyl alcohol 2 to 100 parts by weight of the silicon carbide powder was added to the silicon carbide porous body.
A solution prepared by mixing and dispersing 50 parts by weight was applied by spray coating to form a silicon carbide film with a thickness of 50 μm on all surfaces except the center and the part cut by a certain opening. Next, the silicon carbide porous body on which the silicon carbide film was formed was dried, placed in a Tamman furnace again, and heated to 1800°C at a rate of 2.5°C/min in an argon gas atmosphere of 1 atm. It was heated and held at 1800° C. for 1 hour for firing.

A silicon carbide thin film having fine pores with an average pore diameter of 3 μm was firmly bonded to all surfaces of the thus obtained plate-like element 1 except for the portion cut by the opening at the center.

Most of the floating particles contained in the stock solution passing through the element 1 having the above configuration are separated and removed by a thin film 13 as shown in FIG. Therefore, there are almost no floating particles collected by the matrix 12, and backwashing is easy.

FIG. 3 shows another embodiment.

In FIG. 3, the element 1 has a structure in which the thickness gradually decreases from the opening toward the tip.

FIG. 4 shows an example in which a combination of plate elements is fixed to a multiple support plate 16.

Further, as shown in FIG. 5, by providing a protective tube 1B around the module shown in FIG. 4, the element 1f can be protected.

〔Effect of the invention〕

By using the ceramic filter module of the present invention, which is constituted by a large number of disc-shaped elements made of porous ceramic bodies, the following effects can be obtained.

(1) Compared to the case where a normal cylindrical element is used, the f surface 8t can be made much wider, and the device can be made more compact.

(2) Unlike the cross-flow one-way system used in normal NO-NICAM structures, F-filtration can be performed using the normal F-filtration method, so a large amount of concentrated liquid is not generated, and only waste liquid is treated during backwashing. This makes it easy to process the rear end.

(3) The conventionally used pre-coated type f filter is f
The pre-coating process and backwashing process for the filter material were complicated, but the ceramic filter of the present invention does not require precoating and can be regenerated by simple backwashing, salt cleaning of the element alone, and ultrasonic cleaning with 7-acid. It becomes possible.

Note that the ceramic filter of the present invention is particularly suitable for high temperatures and
It exhibits excellent performance as a high-pressure liquid filter, but the same effect can be obtained as a low-temperature and gas purifier.

Further, by using the outlet 4 shown in FIG. 1 as a concentrate outlet, a cross-flow one-type f filtration is also possible.

[Brief explanation of drawings]

FIG. 1 is an embodiment of the present invention, FIG. 2 is an enlarged view of most of FIG. 1, FIG. 5, FIG. 4, and FIG. 5 are views showing another embodiment, and FIG. 6 is a cylinder Figure 7 shows a filter element with a honeycomb structure. 1... Disc-shaped element, 2... Stock solution inlet, 5...
・F liquid outlet, 4-... discharge port, 5... body, 6, 7...
・Cover, 8... Support material, 9... Coil spring, 10
...Packskin, 11...Fixing bolt, 12...Base material, 15...Thin film, 14...Fixing ring, 15...
・Fixing nut, 16... Support plate, 17... Sealing material,
18... Protection tube, 21... Cylindrical element, 22
...Honeycomb shaped element patent applicant Ebara Corporation IBIDEN Co., Ltd.

Claims (1)

[Claims] 1. A ceramic filter composed of a plurality of plate-like elements made of a porous ceramic body and having an opening in the center, wherein both sides of the element and the surface cut at the time of opening are The element is configured such that the different end faces become the fluid inflow side and the surface cut at the time of opening becomes the fluid outflow side, and the element has a base body made of a ceramic porous body and a fluid inflow side surface of the base body that is smaller than the base body. A ceramic filter characterized by having a ceramic thin film having an average pore diameter. 2. The ceramic filter according to claim 1, wherein the plate-like element gradually becomes thinner from the opening toward the tip. 3. The ceramic filter according to claim 1 or 2, wherein at least one side of the plate-like element is wavy or uneven. 4. The thickness of the thin film is 5 to 200 μm, and the average pore diameter is 0.
．． The average pore diameter of the matrix is sufficiently larger than the average pore diameter of the thin film, the range is within the range of 1 to 600 μm, and the porosity is 2
The ceramic filter according to claim 1, 2, or 3, which has a content of 5% by volume or more. 5. The ceramic porous body mainly contains silicon carbide,
Claims 1 to 4 are porous bodies manufactured from any one or a mixture of two or more selected from silicon nitride, alumina, zirconia, magnesia, sialon, cordierite, mullite, and titanium oxide. A ceramic filter described in any one of the above.