JP3372602B2 - Apparatus and method for removing impurities in air - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device and method for removing impurities contained in air, and more particularly to gaseous components such as gas components and fine particles (hereinafter referred to as "gaseous" in the specification) due to gas-liquid contact. The term "impurities" generally refers to impurities such as gas components and fine particles contained in air) and a removing method .

[0002]

2. Description of the Related Art In addition to dust, air contains a slight amount of gaseous impurities. Such gaseous impurities are not only harmful to the human body, but when mixed in a manufacturing atmosphere such as a semiconductor, they may cause deterioration of electric characteristics of the device. Further, even when vapors of various chemicals used in the semiconductor and liquid crystal manufacturing process leak into the clean room, the concentration of the gaseous chemical contained in the circulating air is increased, which may deteriorate the quality of the chemicals. further,
Not only in the device manufacturing process such as semiconductors, but also in various machine manufacturing factories, food-related factories, animal farms, etc.
Exhaust gas or the like discharged in the chemical liquid treatment step has a considerable influence on the surrounding environment, and may eventually cause environmental pollution. From such a background, establishment of a technique for efficiently removing gaseous impurities contained in the air is desired.

Among such methods for removing gaseous impurities such as gas components and fine particles in the air, the removal of impurities by an absorption method has been conventionally performed for inorganic impurities. As such an absorption method, a wet method using water or a special absorption solution as a gas absorbing solution, and a dry method in which gas is removed by an adsorption filter filled with a gas adsorbent and impregnated are known. The wet method requires a large amount of absorbing liquid in order to improve the removal efficiency of the impurity gas, in spite of less deterioration of performance and little change with time. Moreover, according to the adsorption filter of the dry method, without installing large-scale equipment,
Although it is possible to remove the impurity gas, the adsorption capacity deteriorates over time, and thus periodical maintenance such as replacement and regeneration is necessary.

[0004]

In the conventional wet method, when the absorbing liquid and the air come into contact with each other, the moisture concentration in the air has not reached a saturated state, and the temperature of the absorbing liquid is the dew point temperature of the air. If it is higher than this, the moisture in the absorbing liquid evaporates and raises the moisture concentration in the air.
There has been a problem because the higher the contact efficiency between the gas and the liquid in order to improve the impurity removal performance, the stronger the tendency becomes. In particular, when treating impurities in the intake air for a 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. Since it has to be dehumidified by cooling to the dew point temperature, in the conventional wet method, the moisture evaporated in the air due to the contact between the absorbing liquid and the air must be additionally dehumidified, resulting in poor efficiency.

Further, in the conventional dry method, the performance of the adsorbent deteriorates with the lapse of processing time as described above, and therefore it is necessary to regularly replace 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, it is necessary to increase the filling rate of the adsorbent with respect to the adsorption filter, resulting in a large pressure loss when the treated air passes through the adsorption filter. There was a problem that it required the blast power.

The present invention has been made in view of the problems of the conventional air impurity removing device.
Therefore, the purpose is to increase the gas concentration 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. It is an object of the present invention to provide a new and improved device and method for removing impurities contained in target air, which are capable of removing gaseous impurities such as particles and fine particles and are easy to maintain.

In order to solve the above problems, according to the present invention, a chamber capable of circulating outside air containing impurities, for example, gaseous impurities such as gas components and fine particles from upstream to downstream, and installed in the chamber. liquid substance capable capture impurities contained in the outside air are, for example, a pure water external
Impurity removing means that can be recovered after contact with the atmosphere
And the chamber installed upstream of the impurity removal means
Cooling coil that can directly cool the outside air taken in to the water saturated state, and the liquid inside the impurity removing means.
The temperature of the solid substance is approximately the dew point temperature of the outside air that the liquid substance contacts.
From temperature control means capable of adjusting to almost equal temperature,
An apparatus for removing impurities in the air is provided.

Further in accordance with the present invention, an object containing impurities
Cool the air stream to a water saturated state and add it to the above target air stream.
The temperature of the liquid substance that can take in the impurities contained in
The dew point temperature of the target air flow with which the liquid substance comes into contact
Adjust the temperature to almost the same temperature and move the liquid substance to the target air flow.
Method for removing impurities in the air, characterized by contact with
Law is provided.

Further, according to the present invention, it is possible to bring the liquid substance in a droplet state into contact with the target air flow as the impurity removing means for bringing the liquid substance into contact with the target air flow .

[0010]

According to the apparatus and method for removing impurities in the air constituted according to the present invention, the target air is cooled by the cooling means, for example, the circulating air in the clean room, before the gaseous impurities are treated by the impurity removing means. It can be dehumidified by cooling down to the dew point temperature and made into 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 reaches saturation,
Moisture does not move between the gas and the liquid, and therefore the gaseous impurities can be removed without changing the water content of the process air.

Further, the temperature of the liquid substance brought into contact with the treatment air is adjusted by the temperature adjusting means to be substantially equal to the dew point temperature of the treatment air, so that the movement of water between the treatment air and the liquid substance. Can be avoided more effectively.

Further, by adopting a constitution in which the liquid substance in the form of liquid drops is introduced into the gas-liquid contact portion, the gas-liquid contact area can be expanded and a high removal efficiency can be obtained .

[0014]

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which an apparatus and method for removing impurities in the air constructed according to the present invention is applied to a clean room outside air treatment air conditioner will now be described in detail with reference to the accompanying drawings. To do.

Outside air processing air conditioner 1 for clean room of FIG.
In the above, in the processing chamber 2 that takes in the outside air from the upstream and supplies the processing air from the downstream to the clean room,
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, an impurity processing device for removing gaseous impurities, that is, a gas removing section 5. A post-processing unit including an air blower unit 6 for generating an air flow, a temperature control unit 7 such as an electric heater for 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 gas components and gaseous impurities such as fine particles introduced into the chamber 2 by the blower unit 6 is first fed to the prefilter 3 by a dry high-performance air filter such as a HEPA filter, for example, 0.
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 transferred to the cooling coil 4 installed upstream of the gas removing section 5 for removing impurities by gas-liquid contact, as will be described later in accordance with the present invention. Then, dehumidification by cooling is performed up to the set dew point temperature in the clean room. As a result, the air temperature of the air flow on the downstream side of the cooling coil 4 is lowered in temperature and reaches a water saturated state.

Next, in the gas removing section 5, the air flow whose air temperature is lowered and is saturated with water is a liquid substance capable of taking in gaseous impurities contained in the air flow, for example, pure water capable of dissolving gas components. To remove impurities in the air. At this time, according to the 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 the temperature adjusting means (not shown). In this way, the temperature of the impurity absorbing liquid such as pure water supplied to the gas removing unit is adjusted to be substantially the same as the dew point temperature of the air flow cooled by the cooling coil 4, and the gas removing unit 5 is brought into contact with gas-liquid. By doing
It is possible to only remove the 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 are in phase contact with each other in the gas-liquid contact portion are lower in temperature than the outside air temperature in the summer, the intermediate period, etc., the solubility of the gaseous impurities is improved. As a result, the absorption efficiency of the impurity absorption liquid improves and the saturation point of absorption increases,
The supply amount of the absorbing liquid supplied to the gas removing unit 5 can be reduced. Further, when the outside air temperature is low such as in winter, it is possible to perform appropriate humidification at the gas-liquid contact portion.
As the gas-liquid contact portion, that is, the gas removing portion 5, the structure shown in, for example, FIGS. 2 to 5 can be adopted as described later, and can be appropriately selected according to the 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, and if necessary, there is a temperature adjusting means 7 such as an electric heater. Indoor set temperature (dry bulb temperature)
It is possible to supply it into the clean room after it has been heated up to 1 minute and dust has been removed by a high-performance filter.

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

The gas-liquid contact portion 9 shown in FIG. 2 is of the air shower type, and a nozzle device 11 for spraying an impurity absorbing liquid such as pure water in the form of mist is provided near the ceiling of the chamber 10. Along with being installed, a draining means 12 for collecting the droplets and discharging them to the outside is installed near the bottom of the chamber 10. Further, the liquid droplets sprayed by the nozzle device 11 have a desired temperature by a temperature adjusting means (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 be scattered to the downstream side, the eliminator 1 for collecting and removing the scattered mist to the downstream side of the gas-liquid contact portion 9 is possible.
It is preferable to install 3 or the like.

The air flow cooled to the set dew point temperature by the cooling coil 4 shown in FIG. 1 and saturated with water contacts the liquid substance such as pure water in the gas-liquid contact portion 9 shown in FIG. The gaseous impurities therein are taken into (dissolved in) pure water and fall downward 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, moisture does not move between the gas and the liquid, so that the humidity of the air flow is kept constant, and Gaseous impurities can be effectively removed.

The gas-liquid contact portion 14 shown in FIG. 3 is of a type using a porous block, and the porous block 16 is installed in the air flow passage in the chamber 15, and the water supply means above it. Impurity absorbing liquid such as pure water sprinkled from 17 slowly flows 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 this embodiment, the absorbing liquid sprinkled from the water supply means 17 can be adjusted to a desired temperature, for example, the set dew point temperature of the air flow to be treated, by the temperature adjusting 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 adjusting means (not shown).

Also in the case of this embodiment, the air flow cooled to the set dew point temperature by the cooling coil 4 shown in FIG. 1 and in a water-saturated state flows downward on the surface and inside of the porous block 16 inside the block. It comes into contact with the impurity absorbing liquid that slowly flows toward, and at that time, the gaseous impurities in the air flow are taken into the absorbing liquid and flow downward, and are collected by the draining 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 the gas-liquid contact portion 14 of this type,
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 becomes large, and high impurity absorption efficiency or removal efficiency can be obtained. Further, since the pure water on the surface and inside the porous block 16 are constantly exchanged, 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 obtained at all times. .

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

In the case of this embodiment, the air flow cooled to the set dew point temperature by the cooling coil 4 shown in FIG. 1 and in the water saturated state slowly flows downward on the surface of the parallel plate. Contact with the impurity absorbing liquid, at which time the gaseous impurities in the air stream are taken up (dissolved) by the absorbing liquid.
It flows downward, is collected by the drainage means 23, and is 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 this embodiment.

Next, referring to FIGS. 6 and 7, a device and a device for removing impurities in the air constructed according to the present invention will be described.
Another embodiment of the removal method will be described. In these embodiments, components having the same functions as the components of the device described in FIG. 1 are designated 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 the impurity gas is further incorporated in the external air conditioner 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 and becomes saturated with water. On the downstream side of the cooling coil 4, a parallel plate type electrode group 31 arranged in parallel with the ionization section 30 and the air flow is installed, and the impurity gas component is subjected to primary ionization or secondary ionization in the ionization section 30. After that, the ionized impurities in the parallel plate electrode group 31 are adsorbed and removed by the electrostatic force. On the surface of the parallel plate type electrode group, the impurity absorbing liquid constantly flows from the upper part to the lower part to prevent saturation of impurity absorption. Further, the temperature of the impurity absorbing liquid is adjusted to be the same as the set dew point temperature of the air flow. Impurity gas components that cannot be completely removed by the parallel plate type electrode group 31 are removed by the gas-liquid contact method in the gas removing unit 5 installed on the downstream side by the above-described method. Therefore, according to the present embodiment. ,
It is possible to obtain a very high efficiency of removing gaseous impurities. Further, depending on the required removal efficiency, the gas removing section on the downstream side can be omitted.

As the ionization method that can be used in this embodiment, it is possible to adopt a corona discharge method, an ultraviolet irradiation method, a soft X-ray irradiation method or the like which can ionize gaseous impurities. The optimum method can be selected according to the application. Further, the parallel plate type electrode group 31 to be used is used by a dry method, and a liquid substance such as pure water is flown from the water supply means 32 arranged above the parallel plate type electrode group 31 to the surface of the parallel plate type electrode. There is a wet method for cleaning the surface and recovering impurities so that the adsorption effect at the flat plate electrode can be continuously maintained, and the optimum method can be selected according to the application. In particular, it is more effective to remove impurities by the soft X-ray irradiation method that does not generate ozone during ionization.

Example of FIG. 7 is further incorporates a gas removal device by contact with the fine charged droplets and gaseous impurities out conditioner 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 becomes a water saturated state. On the downstream side of the cooling coil 4, a spray nozzle 34 for spraying a liquid substance such as pure water sent from the water supply unit 33 and a parallel plate type electrode group 3 arranged in parallel to the air flow.
1 is installed, contacts the minute charged droplets sprayed from the spray nozzle 34, the impurity gas component in the air flow is absorbed (dissolved) in the droplets, and thereafter, the configuration is almost the same as that shown in FIG. In the parallel-plate type electrode group 31 having, is adsorbed and removed by electrostatic force. Impurity gas components that cannot be completely removed by the parallel plate type electrode group 31 are removed by the gas-liquid contact method by the above-described method in the gas removing unit 5 installed on the downstream side, so that the present embodiment is also applicable. It is possible to obtain a very high efficiency of removing gaseous impurities, and thus to obtain high-purity clean air. Note that the gas removing unit on the downstream side may be omitted depending on the required removal efficiency.

In the present embodiment, as the treatment progressed, many minute charged droplets adhered to the surface of the parallel plate electrode, the entire surface was wet, and when the adhered amount increased, the parallel plate electrode moved downward due to gravity. Since the impurities flowing down on the surface and adsorbed can also be discharged at the same time, a high adsorption effect can be continuously maintained without supplying the surface cleaning liquid from the outside by the water supply means 32 as in the embodiment of FIG. be able to.

[0034]

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

Further, the temperature of the liquid substance to be brought into contact with the treatment air is adjusted by the temperature adjusting means so as to be substantially equal to the dew point temperature of the treatment air, so that the movement of water between the treatment air and the liquid substance. Can be avoided more effectively.

Furthermore, by installing a removal device by ionization of gaseous impurities or a removal device by contact between charged mist and gaseous impurities as a pretreatment device, higher removal efficiency can be continuously obtained. become.

[Brief description of drawings]

FIG. 1 is a schematic side view of an embodiment in which an apparatus for removing impurities in air constructed 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 air conditioner of FIG.

FIG. 3 is a schematic side view of a porous block type gas removal unit applicable to the air conditioner of FIG.

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

5 is an explanatory diagram showing an arrangement of parallel flat plates used in the gas removing unit of FIG. 4. FIG.

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

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

[Explanation of symbols]

1 External conditioner 2 chamber 3 pre-filter 4 cooling coils 5 Gas removal section 6 blower 7 Electric heater 8 High-performance filter

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Sato 3-20-9 Nishikuta, Tama-ku, Kawasaki City, Kanagawa Prefecture (56) References JP-A-63-270521 (JP, A) JP-A-62-250925 ( (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 47/00 B01D 51/00

Claims (4)

(57) [Claims] 1. Containing impuritiesOutside airDistributed from upstream to downstream
A chamber that can bethe above Installed in the chamber and aboveOutside airIncluded in
The above liquid substances that can incorporate impuritiesOutside airContacted with
An impurity removing means that can be recovered afterthe above It is installed upstream of the impurity removal means,The above tea
The outside air taken into the room,To water saturation
Can be cooled downCooling coilWhen, The temperature of the liquid substance in the impurity removing means is set to the liquid state.
To a temperature approximately equal to the dew point temperature of the outside air with which the substance contacts
Temperature control means that can be adjusted, A device for removing impurities in the air, comprising: 2. A target air flow containing impurities is saturated with water.
It is possible to take in the impurities contained in the target air flow by cooling to
The target air that the liquid substance comes into contact with the temperature of the liquid substance
Characterized in that the liquid substance is brought into contact with the target air flow by adjusting the temperature to be approximately equal to the dew point temperature of the flow.
The method of removing impurities in the air. 3. The liquid substance in a liquid droplet state is supplied to the target air.
The empty space according to claim 2, which is brought into contact with a flow.
Method for removing airborne impurities. 4. The liquid substance is pure water.
The method for removing impurities in the air according to claim 2 or 3.
Law.