JP3400829B2 - Monolith type ceramic filter - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic ceramic filter having a honeycomb shape capable of realizing a high filtration area and a low filtration resistance and used for precision filtration, ultrafiltration, reverse osmosis and the like.

[0002]

2. Description of the Related Art Conventionally, various studies have been conducted to realize a compact ceramic filter having a high filtration area, and a honeycomb-shaped monolithic ceramic filter made of porous ceramics has been proposed.

In the monolith-type ceramic filter, the filtration liquid filtered by the filtration film formed on the surface of the supply liquid passage flows through the partition wall toward the outer wall and is discharged from the outer wall to the outside of the filter. Therefore, the flow rate of the filtrate in the partition wall increases as it approaches the outer wall.

In the conventional honeycomb-shaped ceramic filter, the partition walls have a constant thickness. Therefore, in the portion near the outer wall, the flow velocity of the filtration liquid in the partition wall is significantly increased, so that the flow resistance is significantly increased and the filtration speed is limited. This becomes more remarkable as the filtration area increases. Therefore, the ceramic filter having a high filtration area is difficult to put into practical use industrially.

In order to solve this problem, ceramic filters and the like provided with a filtrate conduit (Japanese Patent Publication No. 01-501534 and Japanese Patent Publication No. 03-500386) have been proposed.

[0006]

However, the ceramic filter or the like provided with the filtrate conduit disclosed in the above-mentioned Japanese Patent Publication has a complicated structure and requires a complicated manufacturing technique. That is, these ceramic filters, for example,
The monolith honeycomb structure requires additional complex processing or a complex process for combining multiple honeycomb members (slabs) into a filter. These points are major drawbacks in industrial mass production.

A first object of the present invention is to solve the above-mentioned problems, suppress an increase in flow resistance of the filtering solution in the partition wall, and prevent a filtering speed from being restricted. Is to provide.

A further object of the present invention is to provide a ceramic filter having a high filtration area, which is industrially easy to mass produce.

[0009]

According to the present invention, extrusion forming is performed.
The honeycomb cell shaft, which is a through-hole, can be molded according to the shape.
Ceramic honeycomb of porous honeycomb structure parallel to the direction
A Iruta, a portion of the partition wall of the honeycomb structure,
In the direction orthogonal to the axis of the honeycomb cells of the structure
Thicker bulkhead der than the other partition wall to expose the end face on the outer wall surface of stationary
The above object can be achieved by a monolith-type ceramic filter characterized by being a flow resistance relaxation part of the filtrate . (Basic configuration)

[0010] flow resistance alleviating portion preferably has a filtrate discharge hole reaching the outer wall surface of said Hani <br/> cam structure.
Further, the flow resistance alleviating section can suppress an increase in the flow resistance of the filtrate.

Further, the above-mentioned filtrate discharge hole can further suppress an increase in flow resistance of the filtrate. (Second configuration)

A porous membrane having a skeleton as a skeleton can be provided with a filtration membrane having a fine pore size on the cell surface, and the filtration membrane is preferably a ceramic membrane. Further, one or more intermediate layers having a pore size intermediate between these can be provided between the filtration membrane and the honeycomb structure.

[0013]

SUMMARY OF THE INVENTION A honeycomb type is effective as a compact, high filtration area ceramic filter, but as mentioned above, the flow resistance of the filtration liquid is significantly increased, so that the filtration speed is limited and the high filtration area is high. It was difficult to industrially use this honeycomb type ceramic filter. The present invention is a high filtration area monolithic ceramic filter in which the limitation of filtration speed is eliminated by suppressing an increase in the flow resistance of the filtration liquid.

In the case of a parallel cell type honeycomb structure, the outer wall surface of the honeycomb structure means the outer wall surface in the lateral direction orthogonal to the axis of the honeycomb cell (through hole). This monolithic ceramic filter has the basic advantage that it can be easily manufactured by extrusion. In addition, the thick partition walls also greatly contribute to the reinforcement of the strength of the honeycomb structure. The basic structure of the present invention can be applied to the case of the cross-flow type honeycomb structure, and the same applies to the case of the second structure.

Further, since the filtrate discharge hole can be formed in the thick partition wall portion, it is also easy to manufacture.

Flow resistance of the filtrate in the partition (pressure loss Δp)
Is the Kozeny-Carmen formula

[Equation 1] Indicated by.

[0017]

[Equation 2] Therefore,

[Equation 3] Becomes Q Flow rate A Cross-sectional area ε Porosity Δp Pressure loss κ Constant L Distance μ Viscosity S Surface area D Pore diameter

According to this equation, in order to reduce the flow resistance of the filtrate, it is conceivable to increase the cross-sectional area A, increase the pore diameter D, decrease the distance L, increase the porosity ε, etc. . The present invention has been made based on these findings. That is, as also shown in FIGS. 1 to 3, the cross-sectional area A is increased by the portion (flow resistance relaxation portion) (12) in which a part of the partition wall leading to the outer wall (13) is thickened for the filtrate passage. By the hole (14) for draining the filtrate reaching the wall surface,
The distance L is reduced.

[0019]

A preferred embodiment of the monolithic ceramic filter of the present invention is one in which a part of the partition walls of the honeycomb structure is used as a thick wall to form a flow resistance relaxing portion. This is for example shown in FIG.
As shown in, the partition walls (cell walls) can be formed and arranged thickly at a predetermined pitch. The simplest example is a parallel arrangement as shown in FIG. 1, but in FIG. 1, a thick wall portion can be added in the vertical direction. In this case, it is preferable that the horizontal pitches be the same from the standpoint of balancing the honeycomb strength, and especially the discharge pressure of the kneaded material becomes uniform during extrusion molding, and it is preferable from the viewpoint of preventing deformation during firing.

In addition, the flow resistance alleviating portion can be arranged and distributed in an arbitrary pattern within the honeycomb cross section. As long as it is continuous with the outer wall, it may be bent or straight, or any pattern, for example, it may be formed excluding the central portion of the honeycomb cross section, and shortened inward from the outer wall as necessary. It may be extended.

The flow resistance alleviating portion is composed of a part of the partition walls of the honeycomb structure, the thickness of which is thicker than the other partition walls, and the end face is exposed on the outer wall surface of the structure. The thickness of the flow resistance relaxing portion is preferably 1.
5 to 10 times, and more preferably 2 to 5 times. Generally, if the thickness of the flow resistance relaxing portion is thin, the effect of relaxing the flow resistance becomes small, and if it is thick, the filtration area becomes small. An optimum value for this thickness is determined according to the size of the filter (honeycomb structure), the size of the pores of the filtration membrane, and the properties of the stock solution to be filtered. Generally, the larger the filter, the thicker it becomes, and the smaller the pore size of the filtration membrane, the thinner it becomes.
Also, the stock solution with a smaller filtration resistance tends to be thicker. The point is to maximize the amount of filtrate per filter unit.

This is because if it is 1.5 times or less, the effect of the flow resistance relaxation portion is small. On the other hand, if it is 10 times or more, the filtration area per unit volume of the filter becomes small, so that the filtration treatment capacity of the filter decreases. Therefore 2-
Five times is preferable under normal conditions.

The honeycomb structure is preferably 1 μm to 1
A support having a honeycomb structure formed of porous ceramics having an average pore size of 00 μm (more preferably 5 μm to 20 μm) has an average pore size of 50 Å to 5 μm.
It is preferable that a filtration film made of porous ceramics of m is formed.

However, if necessary, a filtration membrane made of a material other than ceramics can be used or can be added to the porous ceramics filtration membrane.

Further, the honeycomb structure may be one in which one or more intermediate layers having an average pore diameter in the middle thereof are formed between the support of the honeycomb structure and the filtration film, if necessary. it can. By providing a ceramic intermediate layer having a pore size of an intermediate size between the support and the ceramic filtration membrane,
It has the effect of preventing the generation of cracks and pin poles in the ceramic filtration membrane and improving the filtration accuracy. In this case, the pure permeation flow rate is slightly lower than that of the filter without the intermediate layer due to the increase in the filtration resistance corresponding to the intermediate layer. However, depending on the required filtration accuracy, the support having a honeycomb structure may be formed without forming the filtration film.

An example of the filter including the intermediate layer is as follows. * Support of honeycomb structure: partition wall thickness = 1 mm, flow resistance relaxation portion thickness = 4 mm, cell size = 2 mm, partition wall pitch 3 to 4 cells. * Average pore size of the intermediate layer = 1.0 μm * Average pore size of the ceramic filtration membrane = 0.2 μm

An appropriate number (preferably at a predetermined pitch) of holes (14) for draining the filtrate which are opened to the outer wall surface (outer peripheral surface) are provided. The direction perpendicular to the cell axis is desirable for reducing outflow resistance and drilling.

The following is an example of a method of manufacturing a support having a honeycomb structure.

An organic binder and water are added to a ceramic raw material having an appropriate particle size, and the mixture is kneaded and extruded into a kneaded clay. If necessary, clay, glass or the like can be added as an inorganic binder. This kneaded material is extruded by an extrusion molding machine having a predetermined die, dried, and then fired.

The material of the porous ceramics may be alumina, silica, zirconia, mullite, spinel, cordierite, carbon, silicon carbide, silicon nitride or the like.

A filtration film made of porous ceramics having an average pore diameter of 50 angstroms to 5 μm is formed on the surface of the filtration liquid supply passageway (11) of the honeycomb structured support shown in FIGS. 1 to 3 to form a ceramic filter. An example of the method for manufacturing the filtration film is shown below.

A solvent such as water, an organic binder, a thawing agent, a pH adjusting agent, etc. are added to a ceramic raw material (powder or colloidal solution) having an appropriate particle diameter and mixed to obtain a slip. This slip is coated on the surface of the filter solution supply passage (11) of the support having a honeycomb structure, dried and then baked to obtain a filter film. Materials for the filtration film include alumina, zirconia, titania, and the like.

In Examples 1 and 2 described later, the cross section of the supply liquid passage (cell) is square and the outer wall is cylindrical, but the cell cross section is triangular, hexagonal or other polygonal shape. Other shapes such as a circle and the like can also be used. The arrangement of the supply liquid passages (cells) is square in Examples 1 and 2, but other arrangements such as hexagonal, concentric, radial, zigzag, etc., depending on the honeycomb structure cell cross-sectional shape and the shape of the outer wall. Can also be The outer shape of the cross section of the honeycomb structure may circle, square, rectangular and other polygons.

[0034]

【Example】

Example 1 100 parts by weight of alumina having an average particle diameter of 40 μm, 8 parts by weight of glass powder having an average particle diameter of 5 μm as an inorganic binder, and methylcellulose 7 as an organic binder.
A predetermined amount of water was added to the parts by weight and kneaded to obtain a kneaded material for extrusion. Extrusion molding was carried out by an extrusion molding machine having a die having a cross-sectional shape as shown in FIG. 1 (however, the thickness of the thick wall portion is exaggerated for convenience of illustration), and then dried. Sufficiently dried support in a baking furnace at 1250 ° C
Then, the support having a honeycomb structure shown in FIG. 1 was obtained. The average pore diameter of the support is 10 μm, and the support diameter is 150.
mm, length 1000 mm, thickness of partition wall 2 mm, thickness of part of partition wall leading to outer wall for flow path (thickness of flow resistance relaxation) (12) 8 mm, size of supply path 1 It is a square with sides of 4 mm.

Alumina fine powder 10 having an average particle diameter of 0.6 μm
0 parts by weight, 75 parts by weight of water, and 40 parts by weight of organic binder (water-soluble acrylic resin, solid content 30%) are put in a poly container and mixed with alumina cobblestone in a ball mill for 24 hours while stirring to slip for forming a filtration film. Got This filtration film forming slip is brought into contact with and adheres to the surface of the supply liquid passage of the support having a honeycomb structure to form a filtration film, and then dried at 1250 ° C.
It was baked at. The average pore diameter of the obtained filtration membrane was 0.2 μm.

The pure water permeation flow rate of the thus obtained ceramic filter at a differential pressure of 1 kg / cm ² was 2.5 m.
^{It was 3} / m ² hr.

(Example 2) As shown in Figs. 2 and 3, a flow resistance reducing portion (12) of a support having a honeycomb structure is used for discharging a filtrate, which penetrates the flow resistance reducing portion and reaches an outer wall surface. It was manufactured in the same manner as in Example 1 except that a plurality of holes (through holes) (14) were provided. The size of the hole (14) for discharging the filtrate is φ4 mm, and the space between the through holes in the same flow resistance relaxation portion is 10 cm.

The pure water permeation flow rate at a differential pressure of 1 kg / cm ² of the thus obtained ceramic filter was 2.7 m.
^{It was 3} / m ² hr.

(Comparative Example) As shown in FIG. 4, the honeycomb structure support was not provided with a portion (flow resistance relaxation portion) (12) in which a part of the partition wall communicating with the outer wall was thickened for the filtrate passage. Other than that, it manufactured like Example 1. The pure water permeation flow rate of the thus obtained ceramic filter at a differential pressure of 1 kg / cm ² was 1.9 m ³ / m ² hr.

(Embodiment 3) FIGS. 5 to 7 show the pattern arrangement of the flow resistance alleviating portion in the present invention as a honeycomb end view. In addition, in FIG. 5, the thick line portion 12 shows a thick wall portion.

[0041]

The monolithic ceramic filter of the present invention is a honeycomb cell having through holes which can be formed by extrusion.
Of the porous honeycomb structure whose axis is parallel to the extrusion direction
Since a ceramic filter, a compact, it is possible to increase the filtration area, as shown in the data of the pure water permeation rate of the embodiment, a portion of the partition wall of the honeycomb structure, the honeycomb of the structure Orthogonal to the axis of the cell
By exposing the end surface to the outer wall surface existing in the direction, which is a partition wall thicker than other partition walls , and by using the filtrate flow resistance relaxation portion,
Since the flow resistance of the filtrate in the partition wall can be reduced, the filtration can be efficiently performed. Furthermore, the monolithic ceramic filter of the present invention does not require a complicated manufacturing process of closing both ends of the supply liquid passage, and can be mass-produced at low cost by extrusion molding. The thickness of the flow resistance relaxation portion is 1.5 to 10 times, especially 2 to 5 times the thickness of other cell partition walls.
Since it may be about double, a large filtration area can be secured in the honeycomb cross section without sacrificing the effective filtration area that acts as a filtration membrane. Also, when forming the discharge hole, it is relatively easy because it is formed in the thick wall portion. In addition, preconditions for achieving the maximum filtration flow rate per unit volume of the filter are given according to the desired precision of filtration and the properties (viscosity) of the liquid to be filtered, etc. The most effective filtration flow rate can be secured.

[Brief description of drawings]

FIG. 1 is a honeycomb end view of a support having a honeycomb structure according to a first embodiment of the present invention.

FIG. 2 is a honeycomb end view of a support having a honeycomb structure according to a second embodiment of the present invention.

3 is a sectional view taken along the line A-A ′ in FIG.

FIG. 4 is a side view of a support having a honeycomb structure of a comparative example.

FIG. 5 is a honeycomb end view showing another example of the arrangement of the flow resistance alleviating portion.

FIG. 6 is a honeycomb end view showing another example of the arrangement of the flow resistance relaxing portions.

FIG. 7 is an end view of a honeycomb showing another example of the arrangement of the flow resistance relaxing portion.

[Explanation of symbols]

11 ... Supply liquid passage (cell) 12 ... Part of partition wall leading to outer wall thickened for filtering liquid passage (flow resistance relaxation portion) 13 ... Outer wall surface 14 ... Hole for discharging filtering liquid

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Kamei 3-36 No. 1 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Noritake Company Limited Limited (56) References Special table 1-501534 (JP, A) Special table 3-500386 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B01D 63/06 B01D 71/02 B01D 39/20 B01D 29/00

Claims (6)

(57) [Claims] 1. A honeycomb having a through hole which can be formed by extrusion molding.
Porous honeycomb structure in which the axis of the cam cell is parallel to the extrusion direction
A ceramic filter forming body, a portion of the partition wall of the honeycomb structure, the said structure
A monolithic ceramic filter characterized by being a partition wall which is exposed to an outer wall surface existing in a direction orthogonal to the axis of a honeycomb cell and which is thicker than other partition walls and serves as a flow resistance relaxation portion for the filtrate . Wherein said flow resistance alleviating portion is monolithic ceramic filter according to claim 1, wherein a filtrate discharge hole reaching said outer wall surface of the honeycomb structure. 3. The monolithic ceramic according to claim 1, wherein the thickness of the flow resistance relaxation portion is 2 to 5 times the thickness of other cell partition walls of the honeycomb structure. filter. 4. The monolith according to claim 1, wherein the thickness of the flow resistance relaxing portion is 1.5 to 10 times the thickness of the other cell partition walls of the honeycomb structure. Type ceramic filter. 5. The honeycomb structure is made of a porous monolith ceramic, and has a porous ceramic membrane having a pore size smaller than that of the honeycomb structure on a cell surface thereof. The monolithic ceramic filter described in Crab. 6. The monolithic ceramic filter according to claim 5, further comprising a porous intermediate layer having a pore size intermediate between the honeycomb structure and the porous ceramic membrane.