JP2002355517A - Equipment for removing impurities in the air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an equipment for removing impurities in the air which can remove gaseous impurities at a high efficiency while keeping the humidity of the air to be treated constant. SOLUTION: The air to be treated is cooled to a prescribed dew point and dehumidified by using a cooling means 4 to get water-saturated air before the gaseous impurities are removed by an impurity removing means 5. As a result, water does not move between gas and liquid when the gas in brought into contact with the liquid since water is saturated in the air. Thus, the gaseous impurities can be removed without changing the moisture content of the air to be treated. The movement of water between the gas and the liquid can be avoided more effectively by controlling the temperature of a liquid material to be brought into contact with the air to be almost equal to the dew point of the air to be treated by using a temperature adjusting means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for removing impurities contained in air, and more particularly to a gaseous impurity such as a gas component or fine particles caused by gas-liquid contact (hereinafter referred to as "gaseous impurity" in the present specification). In this case, impurities such as gas components and fine particles contained in the air are collectively referred to.)
To a removing device.

[0002]

2. Description of the Prior Art In addition to dust, air contains trace amounts of gaseous impurities. Such gaseous impurities are not only harmful to the human body, but also may cause deterioration of the electrical characteristics of the device when mixed in a manufacturing atmosphere such as a semiconductor. Also, when vapors of various chemicals used in the semiconductor and liquid crystal manufacturing processes leak into the clean room, the concentration of the gaseous chemical contained in the circulating air increases, and the quality of the chemicals may be degraded. further,
Not only in the manufacturing process of devices such as semiconductors, but also in various machinery manufacturing factories, food-related factories, animal breeding facilities, etc.
Exhaust gas and the like discharged in the chemical liquid treatment process have a considerable effect on the surrounding environment, and may cause environmental pollution. From such a background, establishment of a technology for efficiently removing gaseous impurities contained in air is expected.

In such a method for removing gaseous impurities such as gas components and fine particles in the air, an inorganic impurity is conventionally subjected to an impurity removal treatment by an absorption method. As such an absorption method, a wet method using water or a special absorption liquid as a gas absorption liquid, and a dry method in which gas is removed by an adsorption filter filled with a gas adsorbent and impregnated are used. The wet method requires a large amount of absorbing liquid in order to increase the efficiency of removing impurity gas, instead of the performance deterioration and the change with time. In addition, according to the adsorption filter of the dry method, without installing large-scale equipment,
Although the impurity gas can be removed, the adsorption capacity deteriorates with time, so that maintenance such as replacement and regeneration processing is required periodically.

[0004]

In the conventional wet method, when the absorbing liquid comes into contact with the air, the water concentration in the air does not reach a saturated state, and the temperature of the absorbing liquid is the dew point temperature of the air. If it is higher than that, the water in the absorbing solution evaporates and raises the water concentration in the air.
If the contact efficiency between the gas and the liquid is increased in order to enhance the impurity removing performance, the higher the contact efficiency, the higher the efficiency. In particular, when processing impurities in the outside air taken in for the clean room used in the semiconductor manufacturing process, it is necessary to control the dew point temperature of the circulating air in the clean room. It has to be cooled and dehumidified to the dew point temperature, and in the conventional wet method, the moisture evaporated in the air due to the contact between the absorbing liquid and the air has to be dehumidified excessively, which is inefficient.

In the conventional dry method, as described above, the performance of the adsorbent deteriorates with the elapse of the treatment time. Therefore, it is necessary to periodically exchange or regenerate the adsorbent in order to maintain the required adsorption capacity. In addition, in order to increase the adsorption efficiency of the removal device, the filling rate of the adsorbent into the adsorption filter must be increased, and as a result, the pressure loss when the treated air passes through the adsorption filter increases, However, there is a problem that the air blowing power is required.

[0006] The present invention has been made in view of the problems of such a conventional air impurity removing apparatus,
Therefore, the purpose is to remove the gas components contained in the target air with high removal efficiency without increasing the water concentration in the target air when removing impurities and without requiring a large amount of blowing power. An object of the present invention is to provide a new and improved apparatus for removing impurities contained in target air, which is capable of removing gaseous impurities such as particles and fine particles and is easy to maintain.

[0007]

According to the present invention, there is provided a target air stream (for example, outside air) containing impurities (for example, gaseous impurities such as gas components and fine particles).
A chamber that can be flowed downstream from upstream,
A liquid substance (for example, pure water) which is provided in the chamber and has a porous body, and which can take in the impurities contained in the target air flow, can be continuously passed through the porous body and exchanged. And an impurity removing means capable of recovering the liquid substance after contacting the liquid substance at right angles to the target air flow, and being disposed near the bottom of the chamber, recovering the liquid substance incorporating the impurities. And a drainage means for draining water to the outside.

Further, according to the present invention, there is provided a chamber capable of flowing a target air flow (for example, outside air) containing impurities (for example, gaseous impurities such as gas components and fine particles) from upstream to downstream, and And a plurality of parallel flat plates arranged in parallel in a direction substantially parallel to and substantially perpendicular to the air flow direction, and the surface of the parallel flat plate can capture the impurities contained in the target airflow. An impurity removing means capable of continuously flowing and exchanging a liquid substance (for example, pure water), and recovering the liquid substance after contacting the liquid substance at right angles to the target air flow;
An apparatus for removing impurities in the air is provided, which is provided near the bottom of the chamber and comprises a drainage means for collecting the liquid substance containing the impurities and draining the liquid substance to the outside.

Further, according to the present invention, it is possible to provide a structure provided with a cooling means provided upstream of the impurity removing means for cooling the target air flow.

Further, according to the present invention, there is provided a temperature control means capable of adjusting the temperature of the liquid substance in the impurity removing means to a temperature substantially equal to the dew point temperature of the target air flow with which the liquid substance comes into contact. The configuration provided may be employed.

[0011]

According to the apparatus for removing impurities in air constituted according to the present invention, before the gaseous impurities are treated by the impurity removing means, the target air is cooled by the cooling means to, for example, the dew point temperature of the circulating air in the clean room. It can be cooled and dehumidified to obtain moisture-saturated air. As a result, when the gas and the liquid come into contact with each other in the impurity removing means, the amount of water in the inlet air has reached saturation, so that the movement of the water between the gas and the liquid is not performed. Gaseous impurities can be removed without changing the water content of the gas.

In addition, the temperature of the liquid substance brought into contact with the processing air is adjusted by temperature control means, for example, so as to be substantially equal to the dew point temperature of the processing air, so that the movement of moisture between the processing air and the liquid substance is achieved. Can be avoided more effectively.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an apparatus for removing impurities in air configured according to the present invention is applied to an outside air processing air conditioner for a clean room will be described in detail below with reference to the accompanying drawings.

An outside air processing air conditioner 1 for a clean room shown in FIG.
In the processing chamber 2 which takes in outside air from the upstream and supplies processing air to the clean room from the downstream,
A pre-filter 3 composed of a dry high-performance air filter such as an EPA filter, a cooling coil 4 installed according to the present invention, and an impurity treatment device for removing gaseous impurities, that is, a gas removing unit 5; And a post-processing unit including a blower unit 6 for generating an air flow, a temperature control unit 7 such as an electric heater for performing temperature control, and a HEPA or ULPA filter for finally removing dust. 8 are sequentially arranged from the upstream side to the downstream side.

The air containing gaseous impurities such as gas components and fine particles introduced into the chamber 2 by the blower unit 6 is first filtered in the pre-filter 3 by a dry high-performance air filter such as a HEPA filter.
Solid impurities of 3 μm or more are removed.

Next, the air from which dust has been removed by the high-performance air filter is supplied to a cooling coil 4 installed upstream of a gas removing section 5 for removing impurities by gas-liquid contact as described later in accordance with the present invention. Then, cooling and dehumidification is performed to the set dew point temperature in the clean room. As a result, the air flow on the downstream side of the cooling coil 4 has a reduced air temperature and has reached a moisture saturated state.

Next, the air stream whose air temperature is lowered and which is in a water-saturated state is supplied to a gas removing unit 5 where a liquid substance capable of taking in gaseous impurities contained in the air stream, for example, pure water capable of dissolving gas components. And impurities in the air are removed. At this time, according to a preferred embodiment of the present invention, the temperature of the impurity absorbing liquid is also cooled to a set dew point temperature in the clean room, for example, around 10 ° C. by a temperature control means (not shown). As described above, the temperature of the impurity absorbing liquid such as pure water supplied to the gas removing unit is adjusted to substantially the same temperature as the dew point temperature of the airflow cooled by the cooling coil 4, and the gas-liquid contact is performed in the gas removing unit 5. By doing
It is possible to remove only gaseous impurities without causing evaporation of the absorbing liquid or condensation of moisture in the air, that is, while keeping the humidity of the air flow constant. At this time, since the gas and the liquid that come into contact with each other at the gas-liquid contact portion are lower than the outside air temperature in the summer, the middle period, or the like, the solubility of the gaseous impurities is improved. As a result, the absorption efficiency of the impurity absorbing liquid is improved, and the saturation point of absorption is increased.
The supply amount of the absorbing liquid supplied to the gas removing unit 5 can also be reduced. When the outside air temperature is low in winter or the like, appropriate humidification can be performed in the gas-liquid contact portion.
As the gas-liquid contact part, that is, the gas removing part 5, the structure shown in, for example, FIGS. 2 to 5 can be adopted as described later, and can be appropriately selected according to required performance. is there.

As described above, the target air from which impurities have been removed is sent further downstream along the air flow formed by the blower unit 4, where it is subjected to temperature control means 7 such as an electric heater if necessary. Depending on the indoor set temperature (dry bulb temperature)
, And after being removed by a high-performance filter, it can be supplied into a clean room.

Next, referring to FIGS. 2 to 5, a preferred embodiment of a gas-liquid contacting gas removing section 5 which can be installed in the apparatus 1 for removing impurities in the air constituted according to the present invention. Will be described.

The gas-liquid contact part 9 shown in FIG. 2 is of an air shower type, and a nozzle device 11 for spraying an impurity absorbing liquid such as pure water in the form of a mist is provided near a ceiling in a chamber 10. At the same time, a drainage means 12 for collecting droplets and draining them to the outside is provided near the bottom of the chamber 10. Further, the droplets sprinkled by the nozzle device 11 are heated to a desired temperature by a temperature control unit (not shown).
For example, it is possible to adjust the dew point temperature of the air to be treated. Further, in this method, since the mist of the impurity absorbing liquid may scatter to the downstream side, the eliminator 1 for collecting and removing the mist at the downstream side of the gas-liquid contact portion 9 may be used.
It is preferable to install 3 or the like.

The air flow which is cooled to the set dew point temperature by the cooling coil 4 shown in FIG. 1 and is in a water-saturated state comes into contact with a liquid substance such as pure water in the gas-liquid contact portion 9 shown in FIG. The gaseous impurities therein are taken in (dissolved) in the pure water, fall down together with the droplets, and are removed to the outside by the drainage means 12. At that time, according to the present invention, since the temperature of the mist is also adjusted to the set dew point temperature, the movement of moisture between gas and liquid does not occur. Gaseous impurities can be effectively removed.

The gas-liquid contact portion 14 shown in FIG. 3 is of a type using a porous block. A porous block 16 is provided in an air flow passage in a chamber 15 and a water supply means on the upper portion thereof. The impurity absorbing liquid such as pure water sprinkled from 17 flows slowly along the surface and inside of the porous block 16, is collected by the drainage means 18 installed at the bottom of the chamber 15, and is discharged to the outside. Also in the case of the present embodiment, the absorption liquid sprinkled from the water supply means 17 can be adjusted to a desired temperature, for example, a set dew point temperature of the air flow to be treated, by a temperature control means (not shown). Further, in the case of the present embodiment, the temperature of the porous block 16 itself can be adjusted to a desired temperature, for example, the set dew point temperature by a temperature control means (not shown).

Also in this embodiment, the air flow which is cooled to the set dew point temperature by the cooling coil 4 shown in FIG. The gaseous impurities in the air stream are taken in by the absorbing liquid and flow downward, and are collected by the drainage means 18 and removed to the outside. The supply amount of the impurity absorbing liquid is set so that the gaseous impurities in the flowing absorbing liquid are not saturated.

In this type of gas-liquid contact section 14,
Since the absorbing liquid such as pure water slowly flows on the surface and inside of the porous block 16, the gas-liquid contact area increases, and high impurity absorption efficiency or removal efficiency can be obtained. Further, since the pure water on the surface and inside of the porous block 16 is constantly replaced, the absorption or dissolution of the impurity gas in the pure water does not reach saturation, so that a stable gas removal efficiency can be always obtained. .

The gas-liquid contact portion 19 shown in FIG. 4 is of a type using a parallel plate, and a plurality of flat plates 21 as shown in FIG. And an impurity absorbing liquid such as pure water sprinkled from a water supply means 22 disposed on the upper surface thereof flows slowly along the surface of the parallel flat plate 21 to form a chamber 20.
Is collected by the drainage means 23 installed at the bottom of the container and discharged to the outside. Also in the case of the present embodiment, the water supply means 22
It is possible to adjust the absorption liquid sprinkled from a desired temperature, for example, the set dew point temperature of the processing air flow, by a temperature control means (not shown). Further, the temperature of the parallel flat plate 21 itself can be adjusted to a desired temperature, for example, the above-mentioned set dew point temperature by a temperature adjusting means (not shown).

In the case of this embodiment, the air flow which is cooled to the set dew point temperature by the cooling coil 4 shown in FIG. 1 and is in a water-saturated state slowly flows down the surface of the parallel plate. It comes into contact with the impurity absorbing liquid, at which time the gaseous impurities in the air stream are taken up (dissolved) in the absorbing liquid
It flows downward and is collected by the drainage means 23 and removed to the outside. Also in this case, the supply amount of the impurity absorbing liquid is set so that the gaseous impurities in the flowing absorbing liquid are not saturated. As a result, a stable and high gas removal efficiency can always be obtained even in the case of the present embodiment.

Next, another embodiment of the apparatus for removing impurities in the air according to the present invention will be described with reference to FIGS. 6 and 7. FIG. In these embodiments, components having the same functions as the components of the apparatus described in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In the embodiment shown in FIG. 6, a gas removing device for ionizing impurity gas is further incorporated in the external controller shown in FIG. That is, in this embodiment, the air flow introduced into the chamber 2 is cooled to the set dew point temperature by the cooling coil 4 after the solid particles are removed by the pre-filter 3, so that the air flow is saturated. Downstream of the cooling coil 4, an ionization unit 30 and a parallel plate type electrode group 31 arranged in parallel with the air flow are provided, and the impurity gas component is primary-ionized or secondary-ionized in the ionization unit 30. Thereafter, impurities ionized in the parallel plate electrode group 31 are adsorbed and removed by electrostatic force. On the surface of the parallel plate type electrode group, the impurity absorbing liquid always flows from the upper part to the lower part, thereby preventing the saturation of the impurity absorption. Further, the temperature of the impurity absorbing liquid is adjusted to be equal to the set dew point temperature of the air flow. The impurity gas components that could not be completely removed by the parallel plate type electrode group 31 are removed by the gas-liquid contact method in the gas removing section 5 provided on the downstream side by the above-described method. ,
It is possible to obtain very high removal efficiency of gaseous impurities. Also, depending on the required removal efficiency, the gas removal unit on the downstream side can be omitted.

As an ionization method that can be used in this embodiment, a corona discharge method, an ultraviolet irradiation method, a soft X-ray irradiation method, or the like that can ionize gaseous impurities can be employed. The most suitable method can be selected according to the application. Further, the parallel plate type electrode group 31 to be used is a method of using a dry method, and by flowing a liquid substance such as pure water from the water supply means 32 disposed above the parallel plate type electrode group 31 to the surface of the parallel plate type electrode, There is a wet method that cleans the surface and collects impurities so that the adsorption effect on the plate electrode can be maintained continuously, and it is possible to select an optimal method according to the application. In particular, it is more effective to remove impurities by a soft X-ray irradiation method that does not generate ozone during ionization.

The embodiment of FIG. 7 further incorporates a gas removing device in contact with the minutely charged droplets and gaseous impurities in the external controller 1 of FIG. That is, in this embodiment, the air flow introduced into the chamber 2 is cooled to the set dew point temperature by the cooling coil 4 after the solid particles are removed by the pre-filter 3, and the air flow is saturated. On the downstream side of the cooling coil 4, a spray nozzle 34 for spraying a liquid substance such as pure water sent from a water supply unit 33 and a parallel plate type electrode group 3 arranged in parallel with the air flow.
1 is provided, and comes into contact with the minutely charged droplet sprayed from the spray nozzle 34, the impurity gas component in the air stream is absorbed (dissolved) in the droplet, and then has substantially the same configuration as that shown in FIG. Is attracted and removed by electrostatic force in the parallel plate type electrode group 31 having The impurity gas component that cannot be completely removed by the parallel plate type electrode group 31 is removed by the gas-liquid contact method in the gas removing unit 5 provided on the downstream side by the above-described method. It is possible to obtain very high removal efficiency of gaseous impurities, and thus to obtain high-purity clean air. In addition, depending on the required removal efficiency, the downstream gas removal unit may be omitted.

In this embodiment, as the treatment progresses, a large number of minutely charged droplets adhere to the surface of the parallel plate electrode, and the entire surface becomes wet. Since the impurities that flow down on the surface and the adsorbed impurities can be discharged at the same time, a high adsorption effect is continuously maintained without supplying a surface cleaning liquid from the outside by the water supply means 32 as in the embodiment of FIG. be able to.

[0032]

As described above, according to the present invention,
Before the gaseous impurities are processed by the impurity removing means, the target air can be cooled and dehumidified by the cooling means to, for example, the dew point temperature of the circulating air in the clean room, thereby obtaining moisture saturated air. As a result, when the gas and the liquid come into contact with the impurity removing means, the amount of water in the inlet air has reached saturation, so that the movement of water between the gas and the liquid is not performed, and therefore, the processing air Gaseous impurities can be removed without changing the water content of the gas. This is a particularly effective means in summer when the moisture concentration in the outside air is high or when dehumidifying operation is required.

The temperature of the liquid substance brought into contact with the processing air is adjusted by temperature control means, for example, so as to be substantially equal to the dew point temperature of the processing air, so that the movement of moisture between the processing air and the liquid substance is controlled. Can be avoided more effectively.

Further, by installing a removing device by ionization of gaseous impurities or a removing device by contacting a chargeable mist with gaseous impurities as a pretreatment device, higher removal efficiency can be continuously obtained. become.

[Brief description of the drawings]

FIG. 1 is a schematic side view of an embodiment in which an apparatus for removing impurities in air configured according to the present invention is applied to an external air conditioner for a clean room.

FIG. 2 is a schematic side view of a nozzle-type gas removing unit applicable to the external controller of FIG.

FIG. 3 is a schematic side view of a porous block type gas removing unit applicable to the external conditioner of FIG. 1;

FIG. 4 is a schematic side view of a parallel plate type gas removing unit applicable to the external controller of FIG. 1;

FIG. 5 is an explanatory diagram showing an arrangement of parallel flat plates used in the gas removing unit of FIG.

FIG. 6 is a schematic side view of another embodiment to which a gas removing device by ionization is added according to the present invention.

FIG. 7 is a schematic side view of still another embodiment to which a spray-type gas removing device is added according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 external air conditioner 2 chamber 3 pre-filter 4 cooling coil 5 gas removing unit 6 blower 7 electric heater 8 high-performance filter

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Katsumi Sato 3-20-9 Nishiikuta, Tama-ku, Kawasaki-shi, Kanagawa F-term (reference) 3L053 BD02 4D020 BA23 BB03 BB07 CB08 CB27 CB28 CB33 CC07 CC09 CC10 CC16 CD01 CD02 DB02 DB06 4D032 AA03 AB02 AB07 AC01 BA06 BB09 CA01

Claims (5)

[Claims] 1. A chamber capable of flowing a target air flow containing impurities downstream of an upstream, and a chamber provided in the chamber, comprising a porous body, wherein the porous body is provided with the target air flow. An impurity removing means capable of continuously flowing and exchanging a liquid substance capable of taking in the contained impurities, and capable of collecting the liquid substance after contacting the liquid substance at right angles to the target air flow, A drainage means installed near the bottom of the chamber for recovering the liquid substance containing the impurities and discharging the liquid substance to the outside; 2. A chamber capable of flowing a target air flow containing impurities downstream from an upstream, and a chamber installed in the chamber and arranged in parallel in a direction substantially parallel to and substantially perpendicular to the direction of air flow. It is possible to continuously flow and exchange a liquid substance capable of taking in the impurities contained in the target air flow on the surface of the parallel flat plate, and to exchange the liquid substance with the target air. An impurity removing means which can be recovered after being brought into contact with the flow orthogonally, and a drainage means which is installed near the bottom of the chamber and recovers and drains the liquid substance incorporating the impurities to the outside, An apparatus for removing impurities in the air, comprising: 3. The apparatus for removing impurities in air according to claim 1, further comprising a cooling means provided upstream of said impurity removing means for cooling said target air flow. . 4. A temperature control means capable of adjusting a temperature of the liquid substance in the impurity removing means to a temperature substantially equal to a dew point temperature of the target air flow with which the liquid substance comes into contact. The apparatus for removing impurities in the air according to any one of claims 1, 2 and 3, wherein: 5. The apparatus for removing impurities in air according to claim 1, wherein the target airflow is outside air.