JP2014136178A - Gas filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gas filter having excellent pollutant removal performance, with low pressure loss.SOLUTION: The honeycomb gas filter has an interior wall composed of active carbon paper. In the cells for constituting the honeycomb, the proportion of cells having one closed end is 50 to 100% and the proportion of cells having both open ends is 0 to 50%. In the cells having one closed end, the ratio of the cells having a closed inlet of gas to the cells having a closed outlet of gas (inlet/outlet) is 30/70 to 70/30. The active carbon paper includes 10 to 90 mass% of active carbon and 10 to 90 mass% of a binder. The active carbon paper has a weight of 20 to 200 g/m. The active carbon has an average particle diameter of 1 to 100 μm.

Description

  The present invention relates to a honeycomb-shaped gas filter whose wall surface inside the filter is made of activated carbon paper.

  Gases emitted from industrial equipment and transportation equipment may contain volatile pollutants such as organic solvents. When the gas is discharged due to problems such as emission regulations and odors, the pollutants contained in the gas are removed. Further, in a clean room or the like, since it is disliked that even a trace amount of contaminants is contained in the atmosphere, clean air from which contaminants have been removed using a filter or the like is used.

  As a method for removing volatile compounds contained in gas or air, a method using a chemical filter is known. Conventionally, as a chemical filter, one in which granular activated carbon is filled in a filter case or one in which activated carbon containing activated carbon inside or on the surface is molded into a pleat shape or a honeycomb shape is used. In order to efficiently remove the pollutants contained in the gas to be treated using the chemical filter, it is important to ensure that the gas to be treated and an adsorbing component such as activated carbon contained in the chemical filter are brought into contact with each other.

  However, since the chemical filter filled with granular activated carbon has a large particle size of activated carbon, the contact efficiency between the activated carbon and the gas to be treated is poor and it is difficult to increase the contaminant removal rate. In addition, since the filter becomes large, there is a problem that the pressure loss during ventilation increases.

  In the pleated chemical filter using activated carbon paper, since the gas to be treated passes through the activated carbon paper, the contact efficiency between the activated carbon and the gas to be treated is good, and the removal rate of contaminants can be increased. However, in order to increase the contact efficiency with the gas to be processed and obtain excellent removal performance, it is necessary to increase the number of pleats and increase the surface area. Further, in order to increase the structural strength of the filter itself, it is necessary to incorporate an auxiliary support material into the filter skeleton.

  A honeycomb-like chemical filter using activated carbon paper has low ventilation resistance and excellent strength (Patent Document 1). However, there is room for improvement in the contact efficiency between the gas to be treated and the activated carbon, and it has been desired to develop a honeycomb-shaped chemical filter with better contaminant removal performance.

International Publication No. 2004/110928

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a gas filter having excellent performance for removing volatile contaminants and low pressure loss.

The above-mentioned problem is a honeycomb-shaped gas filter in which the inner wall surface of the filter is made of activated carbon paper; among the cells constituting the honeycomb, the percentage of cells closed at one end is 50 to 100%, and both ends are The ratio of the released cells is 0 to 50%, and the ratio of the cells in which the gas inlet is closed and the cells in which the gas outlet is closed (inlet / outlet) is 30/70. a 70/30, the activated carbon paper, and a 10 to 90% by weight of activated carbon and 10 to 90 wt% of the binder, basis weight of the activated carbon paper is 20 to 200 g / ^{m 2,} and the activated carbon It is solved by providing a gas filter characterized in that the average particle size is 1-100 μm.

  At this time, it is preferable that a wall surface inside the honeycomb is formed by alternately laminating flat sheets and corrugated sheets. It is also preferable that between the two flat sheets, cells with closed inlets and cells with closed outlets are alternately arranged via corrugated sheets.

  It is also preferred that the honeycomb has a cell density of 20 to 400 cpsi. It is also preferable that the activated carbon has a benzene adsorption capacity of 20 to 70% by mass.

  According to the present invention, it is possible to provide a gas filter having excellent performance for removing volatile contaminants and low pressure loss.

It is a perspective view which shows suitable embodiment of the gas filter of this invention. It is the enlarged view which looked at a part of gas filter of Drawing 1 from the direction of an entrance. It is the perspective view which showed one corrugated sheet when the upper and lower flat sheets of the gas filter of FIG. 1 were removed. It is a perspective view which shows the honeycomb molded object by which the both ends of all the cells were open | released.

  The present invention relates to a honeycomb-shaped gas filter whose wall surface inside the filter is made of activated carbon paper. First, the gas filter 1 which concerns on embodiment of this invention is demonstrated easily, referring drawings. The embodiments shown in the drawings show specific examples and do not limit the technical scope of the present invention.

  FIG. 1 is a perspective view showing a preferred embodiment of a gas filter 1 of the present invention. The arrows in FIG. 1 indicate the traveling direction of the gas to be processed. As shown by the arrows in FIG. 1, the gas to be processed enters from the inlet (In), passes through the inside of the gas filter 1, and is discharged from the outlet (Out).

  FIG. 2 is an enlarged view of a part of the gas filter of FIG. 1 as viewed from the inlet direction. As shown in FIG. 2, the gas filter 1 is formed by alternately laminating corrugated activated carbon paper (corrugated sheet 2) and flat activated carbon paper (flat sheet 3). In addition, as shown in FIG. 2, one end of the cell 4 constituting the honeycomb is closed with an adhesive 5. Although not shown in FIG. 2, one end of the outlet is actually closed by the adhesive 5.

  Here, the cell 4 which comprises a honeycomb is demonstrated with reference to FIG. FIG. 3 is a perspective view showing one corrugated sheet 2 when the upper and lower flat sheets 3 of the gas filter 1 of FIG. 1 are removed. As shown in FIG. 3, one end of the inlet or outlet is closed with an adhesive 5. Specifically, when one end of the inlet is closed, the one end of the outlet is open. On the other hand, when one end of the inlet is open, one end of the outlet is closed. In other words, the cell 4 of the gas filter 1 has one of the inlet and outlet ends closed. Further, the cells 4 are alternately closed at one end of the inlet or outlet. Therefore, as shown by the arrows in FIG. 3, the gas to be processed that has entered from the inlet passes through the wall surface 6 of the corrugated sheet 2 or the wall surface (not shown) of the flat sheet 3 at least once and then adjoins. It is discharged from the outlet through the cell 4. The above is a brief description of the gas filter 1 according to the embodiment of the present invention.

  In the present invention, it is important that, among the cells constituting the honeycomb, the proportion of cells closed at one end is 50 to 100%, and the proportion of cells released at both ends is 0 to 50%. If the ratio of the cells with one end blocked is less than 50%, the ratio of the gas to be treated that passes through the activated carbon paper decreases and the pollutant removal performance deteriorates. The percentage of cells with one end closed is preferably 70% or more, more preferably 90% or more, and still more preferably 100%. Here, one end means both one end of the inlet and one end of the outlet. Therefore, in the case of the gas filter 1 shown in FIGS. 1-3, the ratio of the cell which one end obstruct | occluded is 100%, and the ratio of the cell by which both ends were open | released is 0%. On the other hand, if the ratio of the cells released at both ends exceeds 50%, the ventilation resistance is reduced, but the contaminant removal performance is inferior. From the viewpoint of further improving the performance of removing pollutants, the proportion of cells released at both ends is preferably 30% or less, more preferably 10% or less, and still more preferably 0%. .

  It is also important that the ratio (inlet / outlet) of the cells closed at one end to the cells closed at the gas inlet and the cells closed at the gas outlet is 30/70 to 70/30. As a result, the gas to be treated and activated carbon can be efficiently contacted. The ratio (inlet / outlet) is preferably 45/55 to 55/45, and more preferably 50/50 substantially. At this time, it is preferable that every other cell is closed at one end of the inlet or outlet. In the case of the gas filter 1 shown in FIGS. 1 to 3, the cells 4 are alternately closed at one end of the inlet or outlet, and the cell ratio (inlet / outlet) is 50/50.

  The gas filter of the present invention may include cells closed at both ends, but from the viewpoint of increasing the processing amount, cells closed at one end and cells other than those released at both ends, that is, cells closed at both ends are substantially. It is preferable not to include.

  The cell density in the gas filter of the present invention is preferably 20 to 400 cpsi. If the cell density is less than 20 cpsi, the ventilation resistance increases and the life of the gas filter may be shortened. The cell density is more preferably 60 cpsi or more. On the other hand, if the density of the cells 4 exceeds 400 cpsi, corrugation may be difficult. The cell density is more preferably 200 cpsi or less. Here, the cell density (cpsi) means the number of cells per square inch. When the cell shape is corrugated as shown in FIG. 2, the cell density can be adjusted by adjusting the height (h) and pitch (p) of the cell 4.

  The activated carbon paper used for the gas filter of the present invention contains activated carbon and a binder. Here, it is important that the activated carbon paper contains 10 to 90% by mass of activated carbon. When the activated carbon content in the activated carbon paper is less than 10% by mass, the contaminant removal performance is poor. The content of activated carbon is preferably 20% by mass or more. On the other hand, when the content of the activated carbon in the activated carbon paper exceeds 90% by mass, the strength of the activated carbon paper is reduced or dust generation is caused. The content of activated carbon is preferably 80% by mass or less.

  The raw material of the activated carbon is not particularly limited. For example, plant-based materials (for example, wood, sawdust, charcoal, fruit shells such as coconut shells and walnut shells, fruit seeds, pulp production by-products, lignin, molasses, etc. Materials), mineral-based materials (for example, peat, lignite, lignite, bituminous coal, anthracite, coke, coal tar, coal pitch, petroleum distillation residue, petroleum-distilled residue and other mineral-derived materials), synthetic resin-based materials (for example, phenol) Resin, a material derived from a synthetic resin such as polyvinylidene chloride and an acrylic resin). These raw materials can be used alone or in combination of two or more.

  The raw material is carbonized and activated to become activated carbon, but the method of carbonization and activation is not particularly limited. Examples of the carbonization method include a method of treating at 300 ° C. or higher while flowing a small amount of inert gas through a batch rotary kiln.

  Examples of the activation method include gas activation and chemical activation. Gases used in gas activation include water vapor, carbon dioxide gas, oxygen, and combustion gas. Activation temperature is 300-1200 degreeC normally, Preferably it heats up to 900 degreeC. The activation time and the temperature increase rate are appropriately set depending on the amount, type, shape, size, etc. of the raw material. The chemicals used in chemical activation are acids such as sulfuric acid, phosphoric acid, nitric acid, metal hydroxides such as sodium hydroxide, potassium hydroxide, cesium hydroxide, calcium hydroxide, magnesium hydroxide, calcium chloride, zinc chloride And metal chlorides. Processing temperature is 300-800 degreeC normally. The type and concentration of the chemical used for chemical activation are appropriately set according to the amount, type, shape, size, etc. of the raw material.

  In the present invention, it is also important that the activated carbon has an average particle diameter of 1 to 100 μm. When the average particle size is less than 1 μm, the activated carbon scatters and adheres, resulting in poor handling, and when activated carbon paper is dropped as fine powder from the activated carbon paper. The average particle size is preferably 5 μm or more. On the other hand, when the average particle size exceeds 100 μm, paper making becomes difficult or falls off the activated carbon paper, and the contact efficiency between the activated carbon and the gas to be treated is inferior, and the contaminant removal performance is lowered. The average particle size is preferably 70 μm or less. Here, the average particle size means the particle size when the cumulative percentage is 50% in the volume particle size distribution obtained by a laser diffraction / scattering particle size analyzer.

  Moreover, it is preferable that the benzene adsorption capacity of activated carbon is 20-70 mass%. If the benzene adsorption capacity of the activated carbon is less than 20% by mass, the contaminant removal performance may be inferior. More preferably, the activated carbon has a benzene adsorption capacity of 30% by mass or more. When activated carbon is used for the gas filter, the higher the benzene adsorption capacity, the greater the amount of contaminants adsorbed. Accordingly, a higher benzene adsorption capacity is desirable from the viewpoint of extending the life and reducing the size of the gas filter. However, since activated carbon having a high benzene adsorption capacity is expensive to manufacture, an appropriate one is appropriately selected in consideration of the purpose of use and cost.

In the present invention, it is important that the activated carbon paper contains 10 to 90% by mass of a binder.
When the content of the binder in the activated carbon paper is less than 10% by mass, papermaking becomes difficult. The content of the binder is preferably 20% by mass or more. On the other hand, when the content of the binder in the activated carbon paper exceeds 90% by mass, the content of the activated carbon in the activated carbon paper becomes less than 10% by mass, and the contaminant removal performance is poor. The content of the binder is preferably 80% by mass or less.

  The form of the binder is not particularly limited, but is preferably a fiber, more preferably a short fiber. The material of the fiber is not particularly limited, and examples thereof include cellulose fibers such as pulp; polyvinyl alcohol fibers; polyolefin fibers such as polyethylene and polypropylene; polyester fibers; and polyacrylonitrile fibers. The fiber used here is not limited to a single fiber, and may be a composite fiber made of a plurality of polymers. Examples of the composite fiber include a core-sheath type heat-sealable composite fiber having polyester as a core and polyolefin as a sheath. The fiber may contain a flame retardant and other additives.

In the present invention, it is also important that the weight of the activated carbon paper is 20 to 200 g / m ² . In the present invention, since the gas to be treated is passed through the activated carbon paper, one of the characteristics is that a lower basis weight is preferable in order to reduce the pressure loss. However, the strength of the activated carbon paper is insufficient when the basis weight of the activated carbon paper is less than 20 g / m ² . On the other hand, if the basis weight exceeds 200 g / m ² , the airflow resistance becomes too large. From the viewpoint of strength, the basis weight of the activated carbon paper is preferably 50 g / m ² or more. On the other hand, the basis weight is preferably 120 g / m ² or less from the viewpoint of ventilation resistance. The thickness of the activated carbon paper is appropriately set in consideration of the purpose of use and cost, but the thickness is usually 0.05 to 1.0 mm, preferably 0.2 to 0.5 mm.

  The method for producing the activated carbon paper is not particularly limited as long as the activated carbon paper satisfying the above conditions is obtained. For example, a slurry obtained by mixing and stirring activated carbon, a binder, and water can be obtained by a wet papermaking method in which a slurry is poured into a paper machine to remove moisture.

  The manufacturing method of a gas filter is not specifically limited. For example, it can be manufactured by a method in which a flat activated carbon paper and an activated carbon paper molded into a predetermined shape are bonded with an adhesive. If the activated carbon paper is formed into a corrugated shape, the cell becomes a corrugated shape as shown in FIG. The shape of the cell is not particularly limited, and may be a polygonal shape as well as a corrugated shape as shown in FIG. From the viewpoint of easy processing, it is preferable that the wall surface inside the honeycomb be formed by alternately laminating corrugated sheets and flat sheets. Specifically, a corrugated sheet is produced by molding activated carbon paper into a corrugated shape. And the method of laminating | stacking the said corrugated sheet and a flat sheet alternately, adhere | attaching the top part of a corrugated sheet and a flat sheet, and making it cover so that a side surface with a flat sheet is preferable.

  Further, the method for closing one end of the cell is not particularly limited. As a suitable method, there is a method in which an adhesive is poured into an end portion of the cell to close it. At this time, as shown in FIGS. 1 to 3, between the two flat sheets 3, the cells 4 whose inlets are closed and the cells 4 whose outlets are closed are arranged alternately via the corrugated sheets 2. It is preferable. In such a case, in one corrugated sheet, a method of filling the concave portion on the surface of one end thereof with an adhesive and filling the concave portion on the back surface of the other end is simple and preferably employed. The

  The gas filter of the present invention thus obtained is excellent in performance for removing contaminants such as volatile organic compounds and has a low pressure loss, so that it can be used for various applications. For example, it is suitably used for clean rooms.

  Hereinafter, the present invention will be described more specifically with reference to examples. The particle size and benzene adsorption capacity of the activated carbon used in the present examples and comparative examples were measured according to the following methods.

[Measurement of particle size of activated carbon]
The particle size of the activated carbon used in this example and the comparative example was measured by a laser diffraction / scattering method. That is, activated carbon to be measured was placed in ion exchange water together with a surfactant, and ultrasonic vibration was applied to prepare a uniform dispersion. Then, measurement was performed using a laser diffraction / scattering particle size analyzer “Microtrac MT3200” manufactured by Microtrac Corporation of the United States. The activated carbon concentration of the uniform dispersion was adjusted so as to be within the measured concentration range displayed by the analyzer. As a surfactant used for the purpose of uniform dispersion, “Triton-X 100” manufactured by Kao Corporation was used. The surfactant was added in an appropriate amount that does not generate bubbles that affect the measurement. Then, the particle size when the cumulative percentage was 50% in the volume particle size distribution obtained by the above analyzer was defined as the average particle size.

[Measurement of benzene adsorption capacity]
According to JIS K1474, dry air containing benzene was passed through activated carbon, the mass of benzene adsorbed on the activated carbon was measured, and the benzene adsorption capacity (mass%) was determined by the following equation (1). At this time, the measurement was performed using air containing benzene having a concentration of 1/10 of the saturated concentration.
Benzene adsorption capacity (mass%) = [{(sample mass after benzene adsorption) − (sample mass before benzene adsorption)} / (sample mass before benzene adsorption)] × 100 (1)

Example 1
Activated carbon made from coconut shell was pulverized until the average particle size became about 10 μm. The benzene adsorption capacity of the pulverized activated carbon was 65% by mass. The pulverized activated carbon (A), pulp (B), polyester fiber (C), and flame-retardant acrylic fiber (D) are 30:20 (A) :( B) :( C) :( D) by weight ratio. : 40:10 to obtain a mixture. Water was added to the resulting mixture and stirred to obtain a slurry. The obtained slurry was paper-made to obtain activated carbon paper having a thickness of 0.2 mm and a basis weight of 50 g / m ² .

  The obtained activated carbon paper was molded into a corrugated shape (pitch 4.3 mm, mountain height 2.6 mm). Corrugated activated carbon paper (corrugated sheet) and flat activated carbon paper (flat sheet) were alternately laminated. The top part of the corrugated sheet and the flat sheet were bonded together, and the honeycomb molded body 7 having a cell density of 120 cpsi as shown in FIG. 4 was obtained by covering the side surface with the flat sheet. The illustrated honeycomb molded body 7 has a vertical length of 50 mm, a horizontal length of 50 mm, and a depth of 50 mm.

  In the obtained honeycomb molded body, one end of the gas inlet was closed every other cell with an acrylic resin adhesive. On the other hand, one end of the gas outlet closed a cell whose inlet was not closed. In this way, a gas filter as shown in FIG. 1 was obtained. In this gas filter, the percentage of cells with one end blocked is 100%, and the percentage of cells with both ends open is 0%. Moreover, the ratio (inlet / outlet) of the cell in which the gas inlet is blocked and the cell in which the gas outlet is blocked is 50/50 among the cells closed at one end.

  Butane gas having a concentration of 300 ppm was allowed to flow from the inlet of the obtained gas filter to the outlet at a flow rate of 10 L / min at 25 ° C. for 5 minutes. And the density | concentration of the butane gas contained in the gas which came out from the exit was measured. It shows that the removal performance of butane gas (volatile organic compound) is excellent, so that this value is small. The results are shown in Table 1.

  Moreover, the ventilation resistance of the obtained gas filter was measured. Specifically, the ventilation resistance was measured by measuring the pressure difference between the inlet and the outlet when air was passed from the inlet at 25 ° C. and a linear velocity of 1 m / sec. The results are shown in Table 1.

Examples 2-6
A gas filter was obtained in the same manner as in Example 1 except that the benzene adsorption capacity of the activated carbon contained in the activated carbon paper, the basis weight of the activated carbon paper, and the cell density of the honeycomb molded body were changed as shown in Table 1. And according to said measuring method, the butane gas concentration and ventilation resistance were measured. The results are shown in Table 1.

Comparative Example 1
A gas filter was obtained in the same manner as in Example 4 except that the gas inlet and outlet were not blocked with an adhesive. That is, in the gas filter of Comparative Example 1, the ratio of cells with one end blocked is 0%, and the ratio of cells with both ends released is 100%. And according to said measuring method, the butane gas concentration and ventilation resistance were measured. The results are shown in Table 1.

Comparative Example 2
The flat activated carbon paper used in Example 1 was used as it was, and the butane gas concentration and the ventilation resistance were measured according to the above measurement method. The results are shown in Table 1.

  As shown in Table 1, when the gas filter of Comparative Example 1 and the gas filter of each Example were compared, the butane gas concentration was greatly reduced. It has been found that the gas filter of the present invention is superior in the removal rate of pollutants contained in the gas to be treated as compared with the conventional honeycomb gas filter. Further, comparing Examples 1 and 4, Examples 2 and 5, and Examples 3 and 6, it was also found that the airflow resistance decreases as the cell density increases.

1 Gas Filter 2 Corrugated Sheet 3 Flat Sheet 4 Cell 5 Adhesive 6 Side Wall 7 Honeycomb Molded Body

Claims (5)

A honeycomb gas filter whose inner wall is made of activated carbon paper;
Of the cells constituting the honeycomb, the proportion of cells closed at one end is 50 to 100%, the proportion of cells released at both ends is 0 to 50%,
Of the cells closed at one end, the ratio of the cells closed at the gas inlet and the cells closed at the gas outlet (inlet / outlet) is 30/70 to 70/30,
The activated carbon paper includes 10 to 90 mass% activated carbon and 10 to 90 mass% binder,
A gas filter, wherein the weight of the activated carbon paper is 20 to 200 g / m ² and the average particle diameter of the activated carbon is 1 to 100 μm.   The gas filter according to claim 1, wherein a wall surface inside the honeycomb is formed by alternately laminating flat sheets and corrugated sheets.   The gas filter according to claim 2, wherein between the two flat sheets, the cells with closed inlets and the cells with closed outlets are alternately arranged via corrugated sheets.   The gas filter according to any one of claims 1 to 3, wherein the honeycomb has a cell density of 20 to 400 cpsi.   The gas filter according to any one of claims 1 to 4, wherein the activated carbon has a benzene adsorption capacity of 20 to 70 mass%.

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