JP2001038137A - Production of clean air and supplying system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce the clean air having the gaseous impurity concn. of <=1 ppb with low energy less than conventional way. SOLUTION: In the production method, dry type dehumidifying devices 10, 20 and 30 having silica gel or metal silicate and having a freely rotatable rotor are connected in three-step series, and the air subjected to dehumidifying treatment at the first step dry type dehumidifying device 10 is subjected to dehumidifying treatment at the second step dry type dehumidifying device 20, and the air subjected to dehumidifying treatment at the second step dry type dehumidifying device 20 is subjected to dehumidifying treatment at the third step dry type dehumidifying device 30 to purify the air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing clean air having a gaseous impurity concentration of 1 ppb or less, and a supply system for supplying the clean air to a target chamber.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, for example, contamination with gaseous impurities in a clean room has become a problem as the degree of integration increases. Therefore, for example, a high-purity nitrogen gas is constantly supplied to a chamber in a manufacturing apparatus or a wafer storage. However, since nitrogen gas is expensive, there is a practical problem in a place where a large amount is required, and it is not preferable from the viewpoint of worker safety. Therefore, recently, it has been proposed to use so-called chemical-free dry air having almost no gaseous impurities instead of high-purity nitrogen gas ("Ultra Clean Technology" Vol. 10, No. 1, (1)
Published February 998)).

[0003] The technique proposed here is that, for example, silica gel or alumina is filled in an adsorption tower, and treated air is passed through the adsorption tower to remove H ₂ O and CO ₂ at a room temperature level, and Pt ( A method of removing gaseous chemical impurities using platinum) or Pd (palladium) as a catalyst, and a method of adsorbing chemical components in treated air to an adsorbent (zeolite, alumina, activated carbon) cooled to about -50 ° C A method in which the processing air is compressed to remove chemical impurities in a catalyst tower, and then water and CO ₂ are removed in an adsorption tower.

[0004]

However, Pt or Pd used as a catalyst is expensive, and requires a separate catalyst tower, which is not preferable in terms of equipment. Further, in the low-temperature adsorption method, the adsorbent must be constantly maintained at such a low temperature, which consumes much energy and requires large-scale equipment, which is not preferable. Furthermore, in the method of compressing the processing air, a dedicated device or the like is separately required for manufacturing the compressed air itself, and naturally, the manufacturing cost of the compressed air itself is increased. As a result, the conventional technique requires a running cost of 1.5 yen / m ³ or more, which is not satisfactory.

[0005] The present invention has been made in view of the above, and in producing the above-mentioned dry clean air,
It is an object of the present invention to provide a method for producing clean air and a clean air supply system which consumes little energy and consequently has low running costs to solve the above-mentioned problems.

[0006]

According to one aspect of the present invention, there is provided a method for producing clean air having a gaseous impurity concentration of 1 ppb or less, comprising a rotatable rotor having silica gel or metal silicate. A dry dehumidifier that dehumidifies the processing air by passing the processing air through the system is connected in series in three stages, and the air dehumidified by the first stage dehumidifier is dried in the second stage. The air dehumidified by the device and the dehumidified air by the second-stage dry dehumidifier is further dehumidified by the third-stage dry dehumidifier to purify the treated air. And a method for producing clean air.

In a system for supplying clean air having a gaseous impurity concentration of 1 ppb or less to a target chamber, the processing air is passed through a rotatable rotor having silica gel or metal silicate. Dry dehumidifiers for dehumidifying the treated air are connected in series in three stages,
The air dehumidified by the first-stage dry dehumidifier is subjected to dehumidification by the second-stage dry dehumidifier, and the air dehumidified by the second-stage dry dehumidifier is subjected to the third-stage dry dehumidification. The second-stage and third-stage dry dehumidifiers are configured to dehumidify the processing air by passing the processing air through rotatable rotors. The air passage area located on the end face side of the rotor is divided into a dehumidification area, a regeneration area, and a purge area, and the purge area is located before the transition from the regeneration area to the dehumidification area by rotation of the rotor. The air dehumidified by the first-stage dry dehumidifier is diverted and a part of the air is introduced into the purge zone of the second-stage dry dehumidifier. The air that passed through the purging section passed through the regeneration section of the third-stage dry dehumidifier. After being mixed with air, the air is introduced into the regeneration area of the second-stage dry dehumidifier, and another part of the diverted air is supplied to the second stage of the dry dehumidifier. The air passing through the dehumidifying section of the second-stage dry dehumidifier is diverted, and a part of the air is introduced into the purge section of the third-stage dry dehumidifier. And the air that has passed through the purge section is introduced into the regeneration section of the third-stage dry dehumidifier, and another part of the diverted air is supplied to the third-stage dry dehumidifier. A clean air supply system, characterized in that it is configured to be introduced into a dehumidification area of a dry dehumidification device, and that air passing through the dehumidification area is introduced into the destination chamber. Suggested.

In this system, a part of the return air from the target chamber is mixed with the air that has passed through the dehumidification section of the second-stage dry dehumidifier before the diversion. May be configured.

According to a fourth aspect of the present invention, a part of the return air from the target chamber is mixed with the air that has passed through the dehumidification section of the first-stage dry dehumidifier before the diversion. You may comprise.

According to another aspect of the present invention, there is provided a system for supplying clean air having a gaseous impurity concentration of 1 ppb or less to a target chamber, wherein treated air is supplied into a rotatable rotor having silica gel or metal silicate. Dry dehumidifiers that pass through and dehumidify the treated air are connected in series in three stages, and the air dehumidified by the first stage dry dehumidifier is dehumidified by the second stage dry dehumidifier. The air that has been treated and dehumidified by the second-stage dry dehumidifier is configured to be dehumidified by the third-stage dry dehumidifier. The processing air is passed through each rotatable rotor to dehumidify the processing air, and the air passing area located on the end face side of the rotor has a dehumidifying area, a regeneration area, a purge area, Separated from the regeneration area by the rotation of the rotor These sections are arranged so that the purge section is located before the transfer, and the air dehumidified by the second-stage dry dehumidifier is diverted, and a part of the air is partially divided into the second-stage dry dehumidifier. The air that has been introduced into the purge zone of the second stage and passed through the purge zone is mixed with the air that has passed through the regeneration zone of the second-stage dry dehumidifier,
It is configured to be introduced into a regeneration section of the third stage dry dehumidifier, and another part of the diverted air is introduced into the dehumidification section of the third stage dry dehumidifier. The air that has passed through the dehumidification area of the third-stage dry dehumidifier is diverted, a part of which is introduced into the purge area of the third-stage dry dehumidifier, and the other part is a regeneration heater. After being heated by the first stage, the air is introduced into the regeneration zone of the third stage dry dehumidifier, and the air passing through the purge zone and regeneration zone is introduced into the regeneration zone of the second stage dry dehumidifier. And the other part of the diverted air is introduced into the destination chamber.

In this case, as described in claim 6, a part of the return air from the target chamber is separated from the air that has passed through the dehumidification section of the second-stage dry dehumidifier before the branching. Or a part of the return air from the destination chamber is mixed with the air that has passed through the dehumidification area of the first-stage dry dehumidifier, as described in claim 7. You may comprise so that it may be mixed before diversion.

According to the findings of the inventors, first, a dry dehumidifier is connected in series in three stages, and the air dehumidified by the first stage dehumidifier is dried in the second stage. If the dehumidifying treatment is performed by a humidifying device and then the dehumidifying treatment is performed by a third-stage dry dehumidifying device, it is possible to produce air having an extremely low dew point of -80 ° C or less. Investigation of the gaseous impurities contained in the processing air also revealed that the gaseous impurities contained in the processing air gradually increased as the processing air passed through the rotor having silica gel or metal silicate. It was found that it could be reduced to 1 ppb or less at the outlet of the third-stage dry dehumidifier at the final stage.

The adsorbent provided on the rotor is silica gel or metal silicate. Some of these types of dry dehumidifiers contain zeolite as a metal silicate. However, since zeolite has a high regeneration temperature and a uniform pore size, it is difficult to remove all organic gas components. Is not very appropriate. Therefore, the metal silicate suitable for the present invention includes a metal silicate mainly composed of silica gel.
However, lithium chloride cannot remove the organic gas component, and thus is difficult to apply to the present invention.

Further, according to the system of the second aspect,
Instead of simply connecting three stages of dry dehumidifiers in series, the air dehumidified by the first stage dehumidifier is diverted and part of the air is purged by the second stage dehumidifier. While being introduced into the section, the air passing through the purging section is mixed with the air passed through the regeneration section of the third-stage dry dehumidifier to form a mixture.
The air introduced into the regeneration zone of the rotor of the second stage dry dehumidifier is passed through the dehumidification zone of the second stage dehumidifier, and a part of the air is diverted, and a part of the air is divided into the third stage dehumidifier. And the air passing through the purge zone is introduced into the regeneration zone of the third-stage dry dehumidifier, and another part of the diverted air is Since it is configured to be introduced into the dehumidification area of the third-stage dry dehumidifier, the capacity of the heater for heating the regeneration air can be reduced. In addition, since the humidity of the air used for regeneration of the rotor of the second-stage dry dehumidifier is lower than in the past, the performance of the rotor itself of the second-stage dry dehumidifier is improved. Therefore, also from this point, it is possible to produce clean air with a low dew point while saving energy.

At the entrance of the regeneration section of each of the second and third stage dry dehumidifiers, the air that has diverted before passing through the rotor of each stage and passed through the purge section is directly mixed (2). Since it is introduced into the regeneration zone (third stage dry dehumidifier) or the regeneration zone (third stage dry dehumidifier), the pressure loss when passing through the rotor can be minimized. Therefore, as will be described in an embodiment described later, a positive pressure state can be realized at the entrance of the regeneration section. Therefore, it is possible to prevent the invasion of moisture from other parts into the rotors of the dry dehumidifiers of the second and third stages, and to perform a suitable regeneration.
In addition, it is possible to prevent a decrease in the ability to adsorb impurities and the ability to reduce humidity.

According to a fifth aspect of the present invention, the cleanest air that has exited from the dehumidifying area of the rotor of the third-stage dry dehumidifier is used for the regeneration area of the rotor of the third-stage dry dehumidifier. Therefore, air with higher cleanliness can be obtained.

[0017]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a system of a clean air supply system according to the present embodiment. This system produces clean air having an ultra-low dew point having a gaseous impurity concentration of 1 ppb or less and -80 ° C. or less. Thus, for example, the system is configured to supply a semiconductor wafer to a storage S.

The outside air OA as the raw material air is led to the processing system duct 1 and first cooled and dehumidified by the outside air processing cooler 2. The cooled and dehumidified air is then mixed with the purge air cooled by the outside air treatment cooler 2 and passed through the purge section 11c of the rotor 11 of the first-stage dry dehumidifier 10.

As shown in FIG. 2, the first-stage dry dehumidifier 10 has a chamber 1 at both end faces of a rotating rotor 11.
2 and 13 are arranged. Each chamber 1
Each of the partitions 2, 13 has three partition plates 14, 14, 14 arranged radially therein to partition the space inside the chambers 12, 13 into three. Correspondingly, the dehumidifying area 11a, the regenerating area 11b, and the purging area 1 are arranged on the end face of the rotor 11 in the order of rotation of the rotor 11 as shown by the thin arrows in FIG.
Three air passage areas 1c are defined. A dehumidification outlet 12a, a regeneration inlet 12b, and a purge outlet 12c for connecting to a duct or the like are formed on the outer end surface of the chamber 12 corresponding to each of these sections. The outer end face of the chamber 13 is also provided with a dehumidification inlet 13a, a regeneration outlet 13b, and a purge inlet 13c corresponding to the three areas.
Are respectively formed.

The rotor 11 is made of silica and Al.
A material obtained by impregnating a base material with a small amount of (aluminum) and Zn (zinc) added is used. That is, for example, fine fibers of a honeycomb fiber paper or a fired body of a ceramic are mainly composed of silica gel and Al (aluminum),
A metal silicate impregnated with a little Zn (zinc) and impregnated with the metal silicate around the fiber can be used. The thickness of the rotor 11 is 400
mm, and the rotation speed of the rotor 11 is set to 4 rotations / hour.

As described above, the first-stage dry dehumidifier 1
The air mixed with the purge air of the rotor 11 of the first stage is removed by the outside air processing fan 3 to the first stage dry dehumidifier 10.
For example, the dew point temperature is reduced to −35 ° C. through the dehumidifying section 11 a of the rotor 11.

The air that has passed through the dehumidification area 11a of the rotor 11 of the first-stage dry dehumidifier 10 is guided to the processing fan 4, cooled by the precooler 5, and then diverted. The air is guided to the purge area 21c of the rotor 21 of the third stage dry dehumidifier 20 and then mixed with the air that has passed through the regeneration area 31b of the rotor 31 of the third stage dry dehumidifier 30 as described later. , Second stage dry dehumidifier 20
The rotor 21 is guided to the regeneration area 21b. Another part of the diverted air is guided to the dehumidification area 21a of the rotor 21 of the second-stage dry dehumidifier 20.

The second-stage dry dehumidifier 20 has basically the same configuration as the first-stage dry dehumidifier 10, and the rotor 2
1 are arranged in the order of rotation of the rotor 21 in the dehumidifying area 21a, the regeneration area 21b, and the purge area 21c, which are processing areas.
Are divided into three air passage areas. The air that has passed through the dehumidification area 21a of the rotor 21 of the second-stage dry dehumidifier 20 is dehumidified to, for example, air having a low dew point of -75 ° C.

The air that has passed through the dehumidifying area 21a of the rotor 21 of the second-stage dry dehumidifier 20 is then guided to the processing fan 6, cooled by the precooler 7, and then diverted upstream of the rotor 21. Then, a part thereof is guided to the purge section 31c of the rotor 31 of the third-stage dry dehumidifier 30. Another part of the diverted air is
Dehumidification area 31 of rotor 31 of third-stage dry dehumidifier 30
a.

The third-stage dry dehumidifier 30 has basically the same configuration as the first-stage dry dehumidifier 10 and the second-stage dry dehumidifier 20, and the end face of the rotor 31 is In the order of the rotation direction of the rotor 31, the rotor 31 is divided into three air passage areas, that is, a dehumidification area 31a, a regeneration area 31b, and a purge area 31c. The air that has passed through the dehumidifying section 31a of the rotor 31 of the third-stage dry dehumidifying device 30 is dehumidified, for example, to a very low dew point of -90 ° C to -110 ° C. ing.

The air that has passed through the dehumidifying section 31a of the rotor 31 of the third-stage dry dehumidifier 30 is heated by a heating coil (not shown) or a cooling coil (not shown) as required. After being set to an intended temperature by cooling or the like, it is transferred to the storage S as the air supply SA through the air supply duct 8.

After being cooled by the pre-cooler 7, the air that has been diverted upstream of the rotor 31 and introduced into the purge section 31 c of the rotor 31 of the third-stage dry dehumidifier 30 cools the rotor 31. Then, after being heated by the regeneration heater 41, it is guided to the regeneration area 31b of the rotor 31 by the regeneration fan 42, whereby the regeneration of the rotor 31 is performed.

Since the air that has passed through the regeneration section 31b of the rotor 31 of the third-stage dry dehumidifier 30 has low humidity and high temperature, it is used for regeneration of the rotor 21 of the second-stage dry dehumidifier 20. Can be. In the present embodiment, the temperature is further increased by the second-stage regeneration heater 44 to increase the temperature.
As described above, since the air that has passed through the regeneration section 31b has a low humidity and a high temperature, the capacity of the regeneration heater 44 can be small.

On the other hand, the air guided to the purge area 21c of the rotor 21 of the second stage dry dehumidifier 20
After being cooled, the air is mixed with the air heated by the regeneration heater 44 and guided to the regeneration area 21b of the rotor 21 of the second-stage dry dehumidifier 20 by the regeneration fan 45. It is used for playback. As described above, the capacity of the second-stage regeneration heater 44 can be reduced, and the humidity of the air used for the regeneration is reduced to the value of the conventional 2
Since it can be made lower than in the case of the stage type, the performance of the rotor 21 of the second stage dry dehumidifier 20 is improved as compared with the conventional case.

The air that has passed through the regeneration section 21b of the rotor 21 of the second-stage dry dehumidifier 20 and exited from the outlet is heated again by the regeneration heater 46, and is regenerated by the regeneration fan 47. 10 are guided to the regeneration area 11b of the rotor 11 and used for regeneration of the rotor 11, and then the exhaust EA
Is discharged as On the other hand, since the purge air that has passed through the purge section 11c of the rotor 11 is air having a relatively low outlet temperature and low humidity, the purge air is cooled again by using a part of the outside air processing cooler 2 through the purge duct 48. ,
It is mixed with the outside air OA and used as processing air.
D1 to D4 in FIG. 1 are dampers appropriately interposed in the duct for adjusting the air volume.

The return air RA1, RA2, R from the storage S
A3 is supplied by the corresponding return air ducts 51, 52, 53, respectively, to the outside air O introduced upstream of the outside air processing cooler 2.
A, or mixed with air dehumidified in the dehumidification section 11a of the first-stage dry dehumidifier 10, and further dehumidified in the dehumidification section 21a of the second-stage dry dehumidifier 20. Mixed with the air, and can be introduced into the dehumidification area of each of the rotors 11, 21, 31. These are the dampers D5, D6, D7
Is selected by opening and closing.

The clean air supply system according to the present embodiment is configured as described above, and as described above,
The air after cooling and dehumidification by the outside air processing cooler 2 is 1
The dehumidification is performed in the dehumidification area 11a of the dry dehumidifier 10 of the stage,
For example, the dew point temperature is lowered to −35 ° C. Next, after being cooled and dehumidified by the precooler 5, the dehumidification area 21a of the second-stage dry dehumidifier 20 is further dehumidified, and its dew point temperature is lowered to, for example, -75 ° C. After being cooled and dehumidified again by the precooler 7, the dew point temperature is further lowered to -90 ° C to -110 ° C by the dehumidifying section 31a of the third-stage dry dehumidifying device 30. The air whose dew point temperature has been lowered to the ultra-low dew point as described above is then supplied to the storage S as the supply air SA after the temperature is adjusted by heating and cooling as required.

FIG. 3 shows the results of experiments on the cleaning capacity when the clean air supply system according to the embodiment was actually operated, that is, the capacity for removing gaseous impurities and the capacity for dehumidification. In this table, the “specification value” means a value required for the storage S, and the dew point temperature is −10.
The temperature was less than 0 ° C., the organic gas component and the inorganic gas component were each less than 1 ppb. The organic gas component indicates the total (THC) of the organic gas components, and the “toluene equivalent value” means that the reference value of the measuring device is toluene. Further, “BLK Level” means that it is equivalent to a value measured by a measuring device when pure nitrogen gas or the like is passed, for example, and is a practical lower limit of measurement of a measuring device actually used. As for the inorganic gas components, only representative ones are measured. However, although other inorganic gas components actually exist, the concentration contained in the outside air OA is assumed to be low and negligible.

As can be seen from this table, first, regarding the dehumidifying capacity, the rotor 31 of the third-stage dry dehumidifying device 30 is used.
The dew point temperature when exiting is -114 ° C, which is much lower than -80 ° C in a dry dehumidifier using a rotor, which has been considered impossible. The temperatures at the entrance and exit of each of the dry dehumidifiers 10, 20, 30 are as follows. Inlet temperature of first-stage dry apparatus 10 → 5 ° C, outlet temperature → 23 ° C Inlet temperature of second-stage dry apparatus 20 → 5 ° C, outlet temperature → 7 ° C Inlet temperature of third-stage dry apparatus 30 → 5 ° C, outlet temperature → 6 ° C The regeneration inlet temperature is 120 ° C in all cases.

As for the organic gas component, 0.2 p
pb, which was the lower limit of measurement of the measuring device used. Regarding the inorganic gas components, all were 0.1 ppb.
It was as follows, and an extremely high removal ability was confirmed. Therefore, it can be seen that the value which is generally called clean dry air, the dew point temperature is -100 ° C or -110 ° C, and the gaseous impurity concentration is 1 ppb or less are all cleared. In addition, no catalyst or chemical filter is used, and it is possible to continuously produce purified air.

Moreover, unlike the prior art, a compressor and an expensive catalyst are not used, and the cost is reduced in this respect as well. According to the inventors' calculations, the cost of producing air having the same level of cleanliness and low dew point according to the above-described conventional technology is about 1%.
The running cost can be reduced to 0.5 yen / m ³ or less, which is / ³ or less.

Further, in this embodiment, before passing through the second-stage rotor 21 and the third-stage rotor 31, the flow is divided and introduced into the purge sections 21c and 31c, respectively. The air is mixed with the passed air and introduced into the regeneration area 1b of the second-stage rotor 21 or introduced into the regeneration area 31b of the third-stage rotor 31. The number of passages is small, and the pressure loss is reduced accordingly. Therefore, a positive pressure state can be realized at the entrance of each of the regeneration sections 21b and 31b.

For example, as shown in FIG. 4, after passing through the dehumidifying section 31 of the third-stage rotor 31, the stream is divided and introduced into the purge section 31c, and then compared with the case where heating is performed by the regeneration heater 41, Such a result is obtained. Now, the pressure loss of the rotor 31 is set to 450 Pa in the dehumidification section 31a, 500 Pa in the regeneration section 31b, and 350 Pa in the purge section 31c.
In the system shown in FIG. 4, when the pressure of the processing air is 550 Pa when the air is blown by the processing fan 6 and passes through the pre-cooler 7, the pressure becomes 100 Pa when the air passes through the dehumidification area 31a. After that, the pressure becomes -250 Pa when passing through the purge section 31c, and the pressure becomes negative at the entrance of the regeneration section 31b.
If the pressure is negative, moisture may enter from the outside and get mixed in, and an ultra-low dew point may not be obtained.

As shown in FIG. 4, in order to maintain a positive pressure at the inlet of the regeneration section 31b by using a system for introducing the air passing through the dehumidification section 31a into the purge section 31c, the dehumidification section 31b is used.
A part of the air that has passed through a may be further diverted and introduced as it is into the regeneration section 31b, but then the air with an ultra-low dew point that has passed through the dehumidification section 31a will be further recycled. Therefore, the air volume must be increased, and as a result, the energy consumption increases, which is not practical.

In this respect, according to the present embodiment, as shown in FIG.
Since the gas is introduced into the purge section 31c, the positive pressure of 200 Pa is still maintained at the time when the gas passes through the purge section 31c. Therefore, there is no possibility that moisture will enter the inside of the rotor 31 from the outside, and an ultra-low dew point can be suitably obtained.

In addition, since the return air from the storage S can be used by mixing it with the processing air, the energy saving effect can be obtained from this point as well. As for the adsorbed gaseous impurities, those with a low boiling point are separated on the regeneration side and discharged as exhaust gas.
No effect. Even if the high-boiling point gas does not desorb, even if the high-boiling point organic gas has a very low concentration, the organic gas does not deflower earlier than the life of the rotor, and there is no practical problem.

Next, a clean air supply system according to another embodiment will be described with reference to FIG. In the drawings, devices and the like denoted by the same reference numerals as those of the above-described embodiment indicate the same devices and the like. In this supply system, after a part of the air that has passed through the dehumidification area 31a of the rotor 31 of the third-stage dry dehumidifier 30 is heated by the heater 41 for regeneration,
While being guided to the regeneration area 31b of the rotor 31, the rotor 31
The other part of the air that has passed through the dehumidifying section 31a is guided to the purge section 31c, the air that has passed through both sections is mixed and heated by the heater 44, and then the rotor 21 of the second-stage dry dehumidifying apparatus 20 is rotated. In the reproduction area 21b. In the purge section 21c of the second-stage rotor 21,
Part of the air that has passed through the dehumidification area 21a is introduced.

Although the system having such a configuration requires more energy than the system according to the above-described embodiment, the regeneration of the third-stage rotor 31 passes through the dehumidification zone 31a of the third-stage rotor 31. Since the cleanest air is used, air with higher cleanliness can be obtained. According to the inventors' calculations, the system shown in FIG.
1pp gaseous impurity concentration 0.5 yen / ^{m 3} or less the price
Dry air having a cleanliness of b or less can be supplied to the storage S.

In the above embodiment, the dry dehumidifiers 10, 20, and 30 in each stage have basically the same configuration. However, the dry dehumidifier 10 in the first stage is exceptional. It is not necessary to use the same dry dehumidifiers 20, 30 in the second and third stages. Even if the air exiting the rotor contains particle components, these particles can be removed, for example, by installing an ULPA filter on the outlet side of the third-stage rotor 31.

[0045]

According to the present invention, clean air having a gaseous impurity concentration of 1 ppb or less can be produced while saving energy, and as a result, the running cost can be greatly reduced. Further, an expensive catalyst or the like is not required. In addition, since the rotor of the dry dehumidifier can be maintained at a positive pressure, there is no risk of moisture entering from the outside, and it is possible to produce clean air having a very low dew point.

[Brief description of the drawings]

FIG. 1 is an explanatory view schematically showing a configuration of a clean air supply system according to an embodiment of the present invention.

FIG. 2 is a perspective view of a rotor portion of a first-stage dry dehumidifier used in the clean air supply system of FIG.

FIG. 3 is a table showing measured values of dew point temperature and gas component concentration of outlet air of a dry dehumidifier at each stage when the clean air supply system of FIG. 1 is operated.

FIG. 4 is an explanatory diagram showing pressure losses at respective points in a system in which a flow is divided by passing through a dehumidifying section of a rotor.

FIG. 5 is an explanatory diagram showing pressure loss at each point around a third-stage dry dehumidifier in the system of FIG. 1;

FIG. 6 is an explanatory view schematically showing a configuration of a clean air supply system according to another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dry dehumidifier (1st stage) 11 Rotor 11a Dehumidification area 11b Regeneration area 11c Purge area 20 Dry dehumidifier (2nd stage) 21 Rotor 21a Dehumidification area 21b Regeneration area 21c Purge area 30 Dry dehumidifier ( 3rd stage) 31 Rotor 31a Dehumidification area 31b Regeneration area 31c Purge area D1 to D7 Damper S Storage

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D012 CA01 CA10 CC05 CD01 CE01 CE03 CF02 CF05 CF10 CG01 CJ02 CJ04 CK03 4D052 AA00 CB04 DA02 DA06 DB01 DB04 FA01 GA01 GA04 GB02 GB03 GB04 GB09 GB11 GB12 HA01 HA36 HB02 HB06

Claims (7)

[Claims] In a method for producing clean air having a gaseous impurity concentration of 1 ppb or less, dry dehumidification in which process air is passed through a rotatable rotor having silica gel or metal silicate to dehumidify the process air. The devices are connected in series in three stages, and the air dehumidified by the first stage dry dehumidifier is dehumidified by the second stage dry dehumidifier, and the air is dehumidified by the second stage dry dehumidifier. A method for producing clean air, characterized in that the air subjected to the wet treatment is further dehumidified by a third-stage dry dehumidifier to be purified. 2. A system for supplying clean air having a gaseous impurity concentration of 1 ppb or less to a target chamber, wherein the process air is passed through a rotatable rotor having silica gel or metal silicate to remove the process air. Dry dehumidifiers to be dehumidified are connected in series in three stages, and the air dehumidified by the first stage dehumidifier is dehumidified by the second stage dehumidifier.
The air dehumidified by the second-stage dry dehumidifier is configured to be dehumidified by the third-stage dry dehumidifier. The second-stage and third-stage dry dehumidifiers each include: The processing air is passed through a rotatable rotor to dehumidify the processing air, and the air passage area located on the end face side of the rotor is partitioned into a dehumidification area, a regeneration area, and a purge area. Being
Each of these zones is arranged so that the purge zone is located before the transition from the regeneration zone to the dehumidification zone by rotation of the rotor, and the air dehumidified by the first-stage dry dehumidifier is diverted to Part of the air was introduced into the purge zone of the second-stage dry dehumidifier, and the air that passed through the purge zone was mixed with the air that passed through the regeneration zone of the third-stage dry dehumidifier. Then, it is configured to be introduced into a regeneration section of the second stage dry dehumidifier, and another part of the diverted air is introduced into a dehumidification section of the second stage dry dehumidifier. The air passing through the dehumidification area of the second-stage dry dehumidifier is diverted and a part of the air is introduced into the purge area of the third-stage dry dehumidifier; The air that has passed through the purging zone is supplied to the regeneration zone of the third-stage dry dehumidifier. The other part of the diverted air is introduced into the dehumidification area of the third-stage dry dehumidifier, and the air passing through the dehumidification area is transferred to the destination chamber. A clean air supply system characterized by being configured to be introduced. 3. A part of the return air from the destination chamber is
The clean air supply system according to claim 2, characterized in that the clean air supply system is configured to be mixed with the air that has passed through the dehumidification section of the first stage dry dehumidifier before the branching. 4. A part of the return air from the destination chamber is
The clean air supply system according to claim 2, characterized in that the clean air supply system is configured to be mixed with the air that has passed through the dehumidification section of the first stage dry dehumidifier before the branching. 5. A system for supplying clean air having a gaseous impurity concentration of 1 ppb or less to a target chamber, wherein the process air is passed through a rotatable rotor having silica gel or metal silicate to remove the process air. Dry dehumidifiers to be dehumidified are connected in series in three stages, and the air dehumidified by the first stage dehumidifier is dehumidified by the second stage dehumidifier.
The air dehumidified by the second-stage dry dehumidifier is configured to be dehumidified by the third-stage dry dehumidifier. The second-stage and third-stage dry dehumidifiers each include: The processing air is passed through a rotatable rotor to dehumidify the processing air, and the air passage area located on the end face side of the rotor is partitioned into a dehumidification area, a regeneration area, and a purge area. Being
Each of these sections is arranged so that the purge section is located before the transition from the regeneration section to the dehumidification section by rotation of the rotor, and the air dehumidified by the second-stage dry dehumidifier is diverted to Part of the air was introduced into the purge section of the second-stage dry dehumidifier, and the air that passed through the purge section was mixed with the air that passed through the regeneration section of the second-stage dry dehumidifier. Then, it is configured to be introduced into the regeneration area of the first-stage dry dehumidifier, and another part of the diverted air is introduced into the dehumidification area of the third-stage dry dehumidifier. The air that has passed through the dehumidification area of the third-stage dry dehumidifier is diverted and part of the air is introduced into the purge area of the third-stage dry dehumidifier, After a part is heated by the regeneration heater, regeneration of the third-stage dry dehumidifier is performed. The air introduced into the purge zone and the regeneration zone is introduced into the regeneration zone of the second-stage dry dehumidifier, and another part of the diverted air is introduced. A clean air supply system configured to be introduced into the destination room. 6. A part of the return air from the destination chamber is
The clean air supply system according to claim 5, characterized in that the clean air supply system is configured to be mixed with the air that has passed through the dehumidification section of the dry dehumidification unit of the first stage before the branch flow. 7. A part of the return air from the destination chamber is
The clean air supply system according to claim 5, characterized in that the clean air supply system is configured to be mixed with the air that has passed through the dehumidification section of the dry dehumidification unit of the first stage before the branch flow.