JP2010075791A - Chemical filter, and air-conditioning system having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a corrosive gas removing system that can save space and remove corrosive gases only by a simple process, is excellent in energy efficiency, and can attain a long service life. <P>SOLUTION: The system includes a first filter and a second filter that includes a higher removal rate of corrosive gases than the first filter. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a chemical filter. More specifically, the chemical filter of the present invention relates to a chemical filter for efficiently removing corrosive gas contained in air that is fed to a clean room and circulated. The present invention relates to an air conditioning system including such a chemical filter.

  In general, in a clean room, the indoor environment such as temperature, humidity, airflow, and air cleanliness is controlled by an air-conditioning system in order to perform work properly.

  In particular, in a clean room used for the production of semiconductors and disk media, in order to improve the quality of products such as disk media, the corrosive gas contained in the air circulating in the room is removed by a chemical filter. ing. In addition, when such a clean room is used, the corrosive gas may be removed by using a chemical filter for the outside air before being supplied to the clean room.

  Conventionally known ion-exchange filters, ion-exchange adsorbent-carrying filters, and adsorption-type filters using activated carbon pores are known as such chemical filters. Although these chemical filters have a high corrosive gas removal rate of 90 to 99%, their lifetime decreases in inverse proportion to the anion concentration when applied to air containing anions.

  On the other hand, the newly developed chemical adsorption type redox reaction type chemical filter and the chemical adsorption type neutralization reaction type chemical filter have a longer life but have a corrosive gas removal rate of 70 to 70%. As low as 90%.

  Therefore, there has been no chemical filter that can simultaneously exhibit a removal rate of about 90% and a long life with respect to corrosive gas.

Incidentally, a disk medium as a recording component is inserted into a hard disk drive (HDD) of a personal computer. When this disk medium is contaminated with a corrosive gas such as sulfur oxide (SO _x ), the read / write head (R / W head) of the hard disk drive is contaminated or corroded, resulting in HDD failure. It is known.

For this reason, at the time of manufacturing the disk medium, the corrosive gas such as SO _X is removed from the outside air before being supplied to the clean room by an air washer, and the corrosive gas in the air circulating in the clean room is removed by a chemical filter. It has been removed.

  As described above, the chemical filter includes an ion exchange method, an ion adsorbent supporting method, an adsorption method using activated carbon pores, a chemical adsorption type oxidation-reduction reaction method, and a neutralization reaction method. In particular, a method having a high removal efficiency of corrosive gas and a long life is an ion exchange method.

  In manufacturing the disk medium, a fluorine-based lubricant is applied to the surface of the disk medium using a fluorine-based solvent. For this reason, there exists a possibility that the fluorine ion which is an anion may generate | occur | produce in large quantities by decomposition | disassembly of the said solvent and the said lubricant. Thus, when a large amount of anions are generated, an excellent lifetime is not realized in the conventional chemical filter.

  In view of such circumstances, development of techniques for extending the lifetime of chemical filters of an ion exchange system, an ion adsorbent support system, or an adsorption system using pores of activated carbon has been performed, and the following techniques are disclosed.

  In Patent Document 1, a gas treatment liquid is prepared by passing an inorganic salt aqueous solution while applying an electric current to an ion transfer device in which one or more ion exchange membranes are arranged between a positive electrode and a negative electrode. There has been disclosed a method for removing harmful gas components in a gas, wherein a gas to be treated is brought into contact with the gas processing solution to absorb the harmful gas components in the gas into the gas processing solution.

JP 2003-24735 A

  However, the following problems are inherent in the above technique.

  That is, in the technique disclosed in Patent Document 1, it is necessary to install an ion moving device, so that a large space is required for the entire device for removing the corrosive gas.

  Further, in this technique, when removing the corrosive gas, in order to prepare the gas treatment liquid in advance, the inorganic salt aqueous solution must be passed through the ion transfer device, and the predetermined purpose is achieved only by a simple process. Can not.

  Furthermore, in this technique, in order to generate the gas treatment liquid, it is necessary to continue to apply a voltage to the ion transfer device, and thus excellent energy efficiency cannot be realized.

  In addition, in recent years, there is a demand for increasing the service life of corrosive gas removal systems.

  Accordingly, an object of the present invention is to provide a corrosive gas removal system that can save space, remove corrosive gas by a simple process, is excellent in energy efficiency, and can achieve a long life. There is to do. Moreover, the objective of this invention is providing an air conditioning system provided with such a system.

  The present invention relates to a chemical filter that includes a first filter and a second filter that has a higher removal rate of corrosive gas than the first filter. The chemical filter of this invention is used in order to remove efficiently the corrosive gas contained in the air which is sent and circulated to a clean room. In the chemical filter of the present invention, the first filter is preferably a chemisorption type redox reaction type filter or a chemisorption type neutralization reaction type filter. In the chemical filter of the present invention, it is preferable that the second filter is an ion exchange type filter or an ion adsorbent carrying type filter.

  The present invention includes an air conditioning system including the chemical filter.

  The chemical filter of the present invention can save space, can remove corrosive gas only by a simple process, is excellent in energy efficiency, and can achieve a long life. For this reason, if the chemical filter of the present invention is used, the corrosive gas can be removed with high efficiency. As a result, the corrosive gas contained in the circulated air fed to the clean room can be efficiently removed.

<The process leading to the idea of the present invention and the principle of the present invention>
The present inventor diligently studied a corrosive gas removal system that can save space, remove corrosive gas by only a simple process, is excellent in energy efficiency, and can achieve a long life. did. As a result, the object is achieved by making the system a chemical filter including a first filter and a second filter having a high removal rate of corrosive gas with respect to the first filter. The conclusion was reached. Specific findings obtained in the process of drawing such conclusions are as follows.

  First, the present inventor has found that it is preferable not to use the ion transfer device of Patent Document 1 in the corrosive gas removal system in order to realize space saving. In addition, when the present inventor does not use the ion transfer device, the gas treatment liquid does not need to be prepared in advance, so that the corrosive gas can be removed by a simple process, and the voltage is continuously maintained. It was also confirmed that the energy efficiency is excellent because no application is required.

  Therefore, the present inventor decided to use only the chemical filter as a corrosive gas system that realizes the removal of the corrosive gas in the gas without using the ion transfer device of Patent Document 1. Here, the chemical filter is a filter that removes corrosive gas by chemical means (for example, adsorption).

  Furthermore, the present inventor examined the structure of the chemical filter, particularly a configuration capable of extending the life. Specifically, a combination mode of two types of filters having different corrosive gas removal rates was specifically examined.

  Examples of the filter having a relatively low removal rate of corrosive gas (hereinafter sometimes referred to as “low removal filter”) include a redox reaction type filter and a neutralization reaction type filter. On the other hand, filters having a relatively high removal rate of corrosive gas (hereinafter sometimes referred to as “high removal filter”) include an ion exchange type filter and an ion adsorbent carrying type filter.

  Here, the low removal filter has a low ability to capture corrosive gas components, and the consumption rate of the reactive group of the adsorbent used in the filter is low. Therefore, when used alone, the lifetime is relatively long. On the other hand, the high removal filter has a high ability to capture corrosive gas components and the consumption rate of the reactive group of the adsorbent used in the filter is high, so that the lifetime is relatively short when used alone. .

  Therefore, the present inventor combined these characteristics of the above two types of filters, and first reduced the corrosive gas concentration in the air to some extent by a low removal filter having a relatively long life, and then reduced the corrosive gas concentration. Of air was passed through a high removal filter with a relatively short life.

  According to such an aspect of removing corrosive gas, a low removal filter that has a relatively long life can have a long life even if the corrosive gas concentration in air is considerably high. On the other hand, a high removal filter that has a relatively short life is allowed to pass through air having a corrosive gas concentration reduced to some extent, so that clogging is unlikely to occur, and thus a long life can be achieved.

  From the above, the inventor of the present invention can effectively extend the lifetime of the entire chemical filter in a chemical filter configured by combining two types of filters that each achieve a longer lifetime. The conclusion was reached.

  Hereinafter, an embodiment of the present invention based on the above principle will be described in detail with reference to the drawings. The examples shown below are merely examples of the present invention, and those skilled in the art can change the design as appropriate.

<Chemical filter>
FIG. 1 is a cross-sectional view showing a chemical filter 10a (type 1) of the present invention and a chemical filter 10b (type 2) of the present invention. Each of the chemical filters 10 a and 10 b includes a first filter 12 and a second filter 14 a or 14 b that has a higher removal rate of corrosive gas than the first filter 12. The example shown in FIG. 1 (a) is an example in which a pair of ion exchange type filters 16a and 18a are applied to the second filter 14a, and FIG. 1 (b) is a pair of ion filters of the second filter 14b. This is an example in which ion adsorbent carrying type filters 16b and 18b are applied.

[Chemical filter 10a (Type 1)]
(First filter 12)
The first filter 12 is a component for reducing the concentration of the corrosive gas in the air A by capturing the corrosive gas contained in the air A shown in FIG.

  Corrosive gases include any gas that can degrade the quality of a product, such as a disk medium. For example, halogen-based gas containing halogen such as fluorine, acidic gas such as sulfur oxide (SOx) and nitrogen oxide (NOx), and alkaline gas such as ammonia gas can be used. Air A is a gas (particularly air) containing the corrosive gas.

  It is preferable to use a chemisorption type filter for the first filter 12 from the viewpoint of selective removal of corrosive gas components, particularly fluorine-based ions. For example, an oxidation-reduction reaction type filter or a neutralization reaction type filter can be used.

  The redox reaction type filter is a filter in which an oxidizing agent or a reducing agent is supported on a carrier constituting the filter. Here, the carrying is a concept including all aspects such as impregnation, fixation, and attachment.

  As the carrier, porous members such as activated carbon and fiber materials such as polymer fibers can be used. Specifically, olefinic resins can be used.

  As the oxidizing agent, chlorate or the like can be used, and as the reducing agent, thiosulfate or the like can be used.

  The neutralization reaction type filter is a filter in which an acidic substance or an alkaline substance is supported on a carrier constituting the filter. Here, the terms “support” and “support material” have the same meaning as the terms described in the column of the redox reaction type filter.

  As the acidic substance, phosphoric acid or the like can be used, and as the alkaline substance, calcium oxide or the like can be used.

  The thickness of the first filter 12 is preferably 1 to 15 cm in any of the oxidation-reduction reaction type filter and the neutralization reaction type filter described above. By making it 1 cm or more, it is possible to realize a long life, while by making it 15 cm or less, it is possible to achieve low cost.

  Thus, as the first filter 12, a chemisorption type redox reaction type or neutralization type filter can be used. Hereinafter, an example of the action of a chemisorption type neutralization reaction type filter will be described.

  In the following, an example of adsorbing hydrogen fluoride gas (corrosive gas) used at the time of manufacturing a disk medium by using calcium oxide, which is an alkaline substance, as a substance carried on the carrier constituting the first filter 12 will be described. Indicates.

When the air A containing the hydrogen fluoride gas shown in FIG. 1a passes through the first filter 12, the hydrogen fluoride gas collides with the calcium oxide supported on the carrier. Thereby, the neutralization reaction shown in Formula (1) occurs, and calcium fluoride and water are generated.
CaO + 2HF → CaF ₂ + H ₂ O (1)

  As a result of this neutralization reaction, fluorine-based ions (ion group including at least fluorine ions) in the air A are trapped in the first filter 12, and as a result, hydrogen fluoride gas (corrosive gas) is adsorbed. It will be.

(Second filter 14a)
The second filter 14a captures the corrosive gas still contained in the air whose concentration of the corrosive gas is reduced by the first filter 12 shown in FIG. It is a component for further reducing the concentration of.

  As the second filter 14a, a filter having a higher removal rate of corrosive gas than the first filter 12 is used. As described above, the relationship between the removal rates of both the filters 12 and 14a is obtained from the viewpoint of the characteristics that each of the constituent elements 12 and 14a should have in the combination of both the filters 12 and 14a.

  For example, when the corrosive gas removal rate of the first filter 12 is 70 to 90%, the corrosive gas removal rate of the second filter 14a can be 90% or more.

  The example shown in FIG. 1A is an example in which a pair of ion exchange filters 16a and 18a are applied as the second filter 14a.

  As such a pair of ion exchange type filters, a combination of the anion removal filter 16a and the cation removal filter 18a can be employed.

  Each of the anion removal filter 16a and the cation removal filter 18a is a filter in which an ion exchanger is supported on a carrier constituting the filter.

  As the carrier, a porous member such as activated carbon and a fiber material such as polymer fiber can be used, and specifically, an olefin resin or the like can be used.

  In the case of the anion removal filter 16a, an exchange group such as a quaternary ammonium group or a tertiary amino group can be used as the exchange group of the ion exchanger, while in the case of the cation removal filter 18a, the ion exchanger. As the exchange group, an exchange group such as a sulfonic acid group or a carboxyl group can be used.

  In the example shown in FIG. 1A, the anion removal filter 16a is arranged on the first filter 12 side. However, depending on the type of corrosive gas to be removed, the anion removal filter 16a and the cation removal filter are arranged. The arrangement order with 18a may be changed.

  The thickness of the second filter 14a shown in FIG. 1A is preferably 0.5 to 50 cm. By making it 0.5 cm or more, it is possible to realize a long life, while by making it 50 cm or less, it is possible to achieve low cost.

(Combination of the first filter 12 and the second filter 14a in FIG. 1A)
In the chemical filter 10a shown in FIG. 1 (a) formed by combining the first filter 12 and the second filter 14a shown above, the gas A is the first as shown in FIG. 1 (a). Passing through the filter 12 reduces the corrosive gas concentration to some extent, and then passes through the second filter 14a to obtain the gas B with further reduced corrosive gas concentration.

  Such a chemical filter 10a does not include an ion transfer device as disclosed in Patent Document 1. Therefore, the chemical filter 10a is a corrosive gas removal system that can realize space saving, can remove the corrosive gas only by a simple process, and is excellent in energy efficiency.

  Further, the chemical filter 10a reduces the corrosive gas concentration in the air by the low removal filter 12 having a relatively long life, and then passes the air after the reduction of the corrosive gas concentration to the high removal filter 14a having a relatively short life. Corrosive gas removal system. For this reason, according to the chemical filter 10a, the long life characteristic inherent in the filter 12 and the long life of the filter 14a due to the reduction of the gas capture burden due to the pre-capture of the corrosive gas by the filter 12 are achieved. In combination, the chemical filter 10a as a whole can have an excellent life. In the view of the present inventor, it is presumed that the chemical filter 10a achieves a life that is about four times as long as the conventional second filter 14a is used alone.

[Method of manufacturing chemical filter 10a (type 1)]
Below, the manufacturing method of the chemical filter 10a (type 1) shown in FIG. 1 and here, especially the installation method are written together. In addition, about the concrete material etc. which are used for each component 12 and 14a of the chemical filter 10a, it is as above-mentioned, Moreover, since any conventionally well-known material etc. can be used, description about these matters Is omitted.

  First, materials (carriers, etc.) to be used for the first filter 12 and the second filter 14a (16a, 18a), which are the components constituting the chemical filter 10a, are prepared.

  Next, for the first filter 12, a carrier is loaded with an oxidizing agent or the like in the case of the oxidation-reduction reaction method, and an acidic substance or the like in the case of the neutralization reaction method.

  On the other hand, for the second filter 14a, an ion exchanger is supported on the carrier for each of the anion removal filter 16a and the cation removal filter 18a.

  Furthermore, the first filter 12 and the second filter 14a (anion removal filter 16a and cation removal filter 18a) prepared in this way are installed as follows.

  For example, first, the first filter 12 that first passes the air A containing the corrosive gas shown in FIG. Next, a second filter 14a (16a, 18a) that allows the passage of air with a reduced concentration of corrosive gas is disposed. In such an arrangement mode, the first filter 12 is always the upstream side in the air flow path, and the second filter 14a is the downstream side.

  Further, regarding the positional relationship between the anion removal filter 16a and the cation removal filter 18a, as shown in FIG. 1A, the anion removal filter 16a is disposed on the first filter 12 side, and the filter 12 of the filter 16a. A cation removing filter 18a can be arranged on the opposite side to the above. However, the arrangement order of the anion removal filter 16a and the cation removal filter 18a based on the first filter 12 may be reversed from the example shown in FIG.

  Further, in the example shown in FIG. 1 (a), the first filter 12 and the second filter 14a, which are components of the chemical filter 10a, are arranged in contact with each other, but these filters 12, 14a are separated from each other. You may arrange. Thus, when adopting the spaced apart arrangement, a housing (not shown) that can accommodate the first filter 12 and the second filter 14a is used, and these are placed at predetermined positions in the housing. The filters 12 and 14a are disposed as appropriate.

[Chemical filter 10b (Type 2)]
The basic configuration and basic manufacturing method of the chemical filter 10b shown in FIG. 1B are the same as the above-described configuration and manufacturing method of the chemical filter 10a. Therefore, hereinafter, only the difference between the chemical filter 10b shown in the figure and the chemical filter 10a will be described.

(Second filter 14b (16b, 18b))
The chemical filter 10b is an example in which a pair of ion adsorbent carrying type filters 16b and 18b are applied as the second filter 14b.

  A combination of the anion removal filter 16b and the cation removal filter 18b can be employed as such a pair of ion adsorbent carrying type filters.

  Each of the anion removal filter 16b and the cation removal filter 18b is a filter in which an ion adsorbent is supported on a carrier constituting the filter.

  As the carrier, a porous member such as activated carbon and a fiber material such as polymer fiber can be used, and specifically, an olefin resin or the like can be used.

  In the example shown in FIG. 1B, the anion removal filter 16b is disposed on the first filter 12 side. However, the anion removal filter 16b and the cation removal filter are selected depending on the type of corrosive gas to be removed. The arrangement order with respect to 18b may be changed.

  The thickness of the second filter 14b shown in FIG. 1B is preferably 0.5 to 50 cm. By making it 0.5 cm or more, it is possible to realize a long life, while by making it 15 cm or less, it is possible to achieve low cost.

(Combination of the first filter 12 and the second filter 14b in FIG. 1B)
The chemical filter 10b shown in FIG. 1 (b) formed by combining the first filter 12 and the second filter 14b described above saves space in the same manner as the chemical filter shown in FIG. 1 (a). It is a corrosive gas removal system that can be realized and can remove corrosive gas only by a simple process and is excellent in energy efficiency.

  Further, according to the chemical filter 10b shown in FIG. 1 (b), as with the chemical filter shown in FIG. 1 (a), the long life characteristics inherent to the filter 12 and the pre-capture of corrosive gas by the filter 12 are achieved. The lifetime of the filter 14b resulting from the reduction of the gas capture burden is combined with the chemical filter 10b as a whole to achieve an excellent lifetime. In the view of the present inventor, it is estimated that the chemical filter 10b also achieves a life that is about four times as long as that of the conventional second filter 14b.

[Method of manufacturing chemical filter 10b (type 2)]
The manufacturing method of the chemical filter 10b (type 2) is generally the same as the manufacturing method of the chemical filter 10a (type 1). Here, in particular, only differences from the method for manufacturing the chemical filter 10a (type 1) (specific method for forming the second filter 14b) will be described.

  For the second filter 14b, an ion adsorbent is supported on the carrier for each of the anion removal filter 16b and the cation removal filter 18b.

[Other chemical filters]
The above is description regarding each chemical filter (type 1, 2) shown to FIG. 1 (a), (b), However, The chemical filter of this invention is not restricted to these two types, 1st A filter and a second filter that has a higher removal rate of corrosive gas than the first filter are sufficient. For example, as the second filter, an adsorption type filter using pores of activated carbon can be used.

<Air conditioning system>
FIG. 2 is a schematic view showing an air conditioning system of the present invention using the above-described chemical filter of the present invention. The air conditioning system 30 shown in the figure includes an external air conditioner 40, an air conditioner 50, and a clean room 60. Moreover, these structural elements 40, 50, and 60 are connected through piping (not shown).

(External machine 40)
The external air conditioner 40 is a component for taking in outside air and reducing corrosive gas in the air. The external air conditioner 40 includes a housing 42, an air washer 44 accommodated in the housing 42, an anion removal filter 46, and a cation removal filter 48.

(Air conditioner 50)
The air conditioner 50 is a component for reducing the corrosive gas in the air purified to some extent by the external air conditioner 40. The air conditioner 50 includes a housing 52 and a chemical filter 54 accommodated in the housing 52. Here, as the chemical filter 54, any chemical filter of the present invention including the chemical filters 10a and 10b shown in FIGS. 1A and 1B can be used. The chemical filter 54 included in the air conditioner 50 of FIG. 2 is an example using the chemical filter 10a of FIG.

  The chemical filter 54 (10a) is an example shown in FIG. 1A as described above.

(Clean room 60)
The clean room 60 is a work area that is provided when work in a clean space is required as in a manufacturing process of a disk medium or the like, and is an area in which corrosive gas generated in the work is reduced and air is further circulated. It is.

  The clean room 60 includes a housing 62, a purification unit 64 housed in the housing 62, partition walls 66a and 66b extending from the purification unit 64 in the direction of the arrow in FIG. 2 (the direction of airflow), and the ends of the partition walls 66a and 66b. And a free access floor 68 having a large number of openings provided between the sections.

  The purification unit 64 includes a plurality of fans 64a arranged in a row in FIG. 2 and a chemical filter 64b. Here, any chemical filter of the present invention including the chemical filters 10a and 10b shown in FIGS. 1A and 1B can be used as the chemical filter 64b. A chemical filter 64b included in the clean room 60 of FIG. 2 is an example in which the chemical filter 10b of FIG. 1B is combined with the organic substance removing chemical filter 20 on the downstream side.

  In the clean room 60 having such a configuration, the space defined by the edge of the purification unit 64, the partition walls 66a and 66b, and the free access floor 68 is a clean space suitable for a manufacturing process of a disk medium or the like.

  In the air conditioning system 30 shown in FIG. 2, gas circulates as follows. That is, the gas C that is the outside air passes through the external conditioner 40, and the gas D in which the corrosive gas is reduced is obtained. Next, the gas D passes through the air conditioner 50, and the gas E in which the corrosive gas is reduced is obtained.

  Further, when the gas E is supplied to the clean room 60, a part of the gas E passes through the chemical filter 64b and the corrosive gas is reduced, and the rest passes through the fan 64a as it is, and the corrosive gas is reduced as a whole. Gas G is obtained.

  The gas G is mixed with the corrosive gas generated by the operation in the clean space to become the gas H and passes through the free access floor 68. Next, a part of the gas H circulates in the clean room 60 as the gas I, the other part is sent from the clean room 60 to the air conditioner 50 as the gas J, and the rest is released to the outside as the gas K. .

  According to the air conditioning system 30 described above, the outside air is supplied to the clean room 60 via the external air conditioner 40 and the air conditioner 50, so that the chemical filter of the present invention disposed in the air conditioner 50 and the clean room 60 is used. Highly efficient reduction of corrosive gas can be realized.

  In the air conditioning system 30, a part of the gas that has passed through the clean space in the clean room 60 is sent again to the air conditioner 50, and the other part is circulated in the clean room 60. For this reason, the air conditioning system 30 is an excellent system in consideration of the environment without releasing all the gas including the corrosive gas generated in the clean space to the outside.

  According to the above-described chemical filter of the present invention, it is possible to save space, remove corrosive gas only by a simple process, and improve energy efficiency by suitably combining two types of filters having different effects of removing corrosive gas. , And a longer life can be realized. For this reason, when the chemical filter of the present invention is used alone or incorporated in an air conditioning system, the corrosive gas can be removed with high efficiency.

  For example, in an air conditioning system incorporating the chemical filter of the present invention, a suitable clean space can be obtained, so that a high-quality disk medium or the like can be manufactured. Therefore, the present invention is promising in that a suitable clean space can be provided in the manufacture of disk media and the like that are required to improve in quality in the future.

It is sectional drawing which shows the chemical filter 10a (type 1) of this invention, and the chemical filter 10b (type 2) of this invention, respectively. It is the schematic which shows the air conditioning system of this invention using the chemical filters 10a and 10b shown in FIG.

Explanation of symbols

10a, 10b Chemical filter 12 First filter 14a, 14b Second filter 16a Ion exchange type anion removal filter 16b Ion adsorbent carrying type anion removal filter 18a Ion exchange type cation removal filter 18b Ion adsorbent carrying type Cation removal filter 30 Air conditioning system 40 Air conditioner 50 Air conditioner 60 Clean room

Claims (5)

A first filter;
A chemical filter comprising: a second filter having a higher removal rate of corrosive gas than the first filter.   2. The chemical filter according to claim 1, wherein the first filter is a chemisorption type redox reaction type filter or a chemisorption type neutralization reaction type filter.   The chemical filter according to claim 1 or 2, wherein the second filter is an ion exchange type filter or an ion adsorbent carrying type filter.   A clean room comprising the chemical filter according to claim 1.   An air conditioning system comprising the chemical filter according to claim 1.

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