JPH06262099A - Equipment for removing impurities in the air - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an apparatus for removing impurities in air, which has high ionization efficiency of impurities and recovery efficiency of ionized impurities. According to the removing apparatus of the present invention, the air containing impurities introduced into the chamber is irradiated with soft X-rays to ionize the impurities and an electric field is formed between adjacent plate electrodes of the ionized impurities. It is possible to collect and remove by the plurality of plate electrodes configured as described above. Since the cleaning liquid is made to flow to the surface of the plate electrode to such an extent that the concentration of impurities in the liquid is not saturated, it is possible to maintain high recovery efficiency. Further, since soft X-rays are used, ozone is not generated, and it is possible to apply to ignitable gas.

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 in air, and more particularly to an apparatus for removing impurities in air by irradiation with soft X-rays.

[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 if vapors of various chemicals used in the semiconductor or liquid crystal manufacturing process leak into the clean room, the concentration of the gaseous chemical contained in the circulating air may be increased, which may deteriorate the quality of the product. further,
Not only in device manufacturing factories 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.

Up to now, there have been known some techniques for removing the gaseous impurities contained in the air as described above. However, all of them have many drawbacks and are currently used only under very limited conditions.
For example, the NOx removal device is effective only for a very high concentration, and has a low removal efficiency for a low concentration of several ppm or less, which is a problem in practicability.

Further, most of harmful gases generated from factories can be treated with a large amount of chemicals. However, in such a treatment technique using a chemical liquid, the components that can be treated are limited by the chemical liquid used, the treatment cost is high, and further, it is impossible to remove to a concentration level in the general atmosphere.

Furthermore, as a low-concentration treatment, there is adsorption removal by activated carbon. However, this also has some drawbacks. First, the service life is short, and the processing performance decreases with the passage of time. As a result, it is necessary to frequently carry out replacement and regeneration by heating, which is very expensive. Further, in order to remove to a lower concentration, the blast pressure loss becomes high, which also causes an increase in running cost.

In addition to this, there is known a technique of ionizing impurities in the air by corona discharge and recovering and removing the ionized impurities. However, in this method, the ionization efficiency of gaseous impurities contained in the air is low,
Since ozone of a considerably high concentration was also generated at the same time, it could not be used to treat the air supplied to the clean room or the air supplied to the living space. In addition, since it utilizes the discharge phenomenon, it cannot be applied to ignitable gas treatment. Furthermore, this corona discharge method was also a method with high running cost.

[0007]

Therefore, in view of the above-mentioned problems of the conventional processing techniques, the object of the present invention is to provide even a low concentration of gaseous impurities contained in the air. Another object of the present invention is to provide a new and improved apparatus for removing impurities in the air, which can be efficiently removed and whose running cost can be kept low.

Still another object of the present invention is that it can increase the ionization efficiency of gaseous impurities contained in the air, does not generate ozone, and does not cause ignition, so that it can be applied to any environment. It is an object of the invention to provide a new and improved device for removing impurities in the air.

Still another object of the present invention is that the recovery of ionized impurities can be carried out quickly and efficiently, and its high absorption efficiency can be maintained for a long period of time. It is an object of the present invention to provide a new and improved apparatus for removing impurities in the air that does not require the dehumidification treatment that was necessary in the treatment.

[0010]

In order to solve the above-mentioned problems, according to the present invention, a target air flow containing impurities can be circulated from upstream to downstream, and introduced into the chamber from upstream. Soft X-ray irradiating means for irradiating the target air flow containing the impurities with soft X-rays,
An apparatus for removing impurities in the air is provided, which is arranged on the downstream side of the soft X-ray irradiating means and comprises a removing means for collecting and removing impurities ionized by the soft X-ray irradiation. .

Further, according to the present invention, the removing means comprises:
It consists of a plurality of plate dust collecting electrodes arranged substantially parallel to the air flow direction, and a voltage is applied to these plate dust collecting electrodes so that an electric field is formed between adjacent plate dust collecting electrodes. Preferably.

Alternatively, according to the present invention, surface cleaning means is provided on the ion adsorption surfaces of the plurality of plate dust collecting electrodes for flowing the surface cleaning liquid to such an extent that the concentration of impurities in the liquid is not saturated. It is preferable.

Furthermore, according to the present invention, the plurality of plate dust collecting electrodes are substantially parallel to the air flow direction,
In addition, it is preferable that the surface cleaning liquids are arranged in parallel in a substantially vertical direction so that the surface cleaning liquid can flow downward from above the ion adsorption surface.

Furthermore, according to the present invention, it is preferable that a filter means for removing dust contained in the air is arranged upstream of the soft X-ray irradiation means.

[0015]

As described above, according to the present invention, by irradiating the target air flow flowing from the upstream side to the downstream side in the chamber with the soft X-rays, the impurities contained in the target air flow are ionized and then ionized. The impurities thus removed can be efficiently removed by the removing means installed downstream of the soft X-ray irradiating means. According to the present invention, since soft X-rays are used for ionizing impurities, it is possible to ionize almost 100% of impurities in the air in a short time. Also,
Since ozone is not generated during ionization of impurities and there is no danger of ignition because the discharge phenomenon is not used,
It can be applied to any environment.

The removing means according to the present invention is composed of a plurality of plate dust collecting electrodes arranged substantially parallel to the air flow direction, and an electric field is formed between the plate dust collecting electrodes adjacent to each other. Therefore, it is possible to effectively adsorb the positively or negatively ionized impurities to the dust collecting electrode of the opposite pole according to the flow of air.

Further, the surface cleaning means according to the present invention is provided,
By flowing the surface cleaning liquid to the ion adsorption surfaces of the plurality of plate dust collecting electrodes to such an extent that the impurity concentration in the liquid does not reach the saturated state, it becomes possible to always keep the ionized impurity adsorption surfaces clean. It is possible to maintain high adsorption performance over a long period of time. Also,
By arranging the plurality of plate dust collecting electrodes in parallel in a substantially vertical direction and flowing the surface cleaning liquid from above to below the adsorption surface of the plate dust collecting electrode, cleaning of the adsorption surface can be performed easily and efficiently. It can be carried out.

Further, the filter means is provided on the upstream side of the soft X-ray irradiating means, and pretreatment for removing dust contained in the air is performed in advance, so that the ionization of impurities in the air by the soft X-ray irradiation is made efficient. In addition to being able to achieve this, the life of the device can be extended.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which an apparatus for removing impurities in the air using soft X-ray irradiation according to the present invention is applied to an outside air treatment air conditioner for a clean room will be described in detail below with reference to the accompanying drawings. Note that FIG. 1 is a schematic side view of the outside air processing air conditioner, and FIG. 2 is a horizontal sectional view of an impurity removal unit portion of the outside air processing air conditioner.

The illustrated outside air treatment air conditioner 1 includes a pretreatment unit 2 including a dry high performance air filter such as a HEPA filter, an impurity removing unit 3 according to the present invention, and an air flow. It is composed of a blower unit 4 for generating, a heat exchanger for adjusting temperature and humidity, etc., and a post-treatment unit 5 equipped with a HEPA or ULPA filter for finally removing dust.
These units are housed in a chamber 8 having an air inlet 6 and an air outlet 7.

Blower 4 incorporated in blower unit 4
The air containing impurities introduced into the chamber from the air inflow port 6 by the air flow forming means such as 0 is first processed by the dry high performance air filter such as the HEPA filter in the pretreatment unit 2 to, for example, 0.3 μm or more. Solid impurities are removed.

Next, the air from which dust has been removed by the high performance air filter is introduced into the impurity removing unit 3. The impurity removing unit 3 includes a soft X-ray emitting device 30 and an ionized impurity recovery plate dust collecting electrode 31.

The so-called soft X-rays (shown by dotted lines in the drawing) having a wavelength of several angstroms to several hundreds of angstroms, which are emitted from the soft X-ray radiating device 30, are radiated to the target air stream to contain impurities contained in the air. Ionize not only gaseous impurities but also fine particles that have passed through the high performance filter.

The soft X-ray referred to in the present specification refers to an X-ray region having a low penetrability, which is easily absorbed by a thin air layer, and its wavelength is generally several angstroms to several hundred angstroms. Is defined to be. As described above, since X-rays in the soft X-ray region used in the present invention have a small penetrating ability, the photon absorption rate of gas molecules is high, and the gas molecules are easily ionized. Moreover, since neutral oxygen atoms (radicals) are not generated in the ionization process, ozone is not generated.

On the other hand, in the light of the ultraviolet region having energy lower than that of the soft X-ray region (that is, on the long wavelength side),
Ionization of gas is possible, but this is a problem because a larger amount of ozone is generated.

Hard X-rays (normal X-rays) higher in energy than the soft X-ray region (that is, on the short wavelength side) are sufficient as ionization energy, but are absorbed by gas molecules (atoms). Hateful. That is, since the light absorption cross-section becomes smaller as the wavelength becomes shorter, the amount of ions generated by the hard X-ray irradiation is very small and it cannot be used for static elimination. Further, in the case of hard X-ray, it is necessary to provide a large-scale shielding means, which is not suitable for practical use.

In the above-mentioned ionization process, in addition to direct ionization due to soft X-ray absorption of impurities, charge exchange reaction between nitrogen and oxygen molecules having higher ionization energy than impurities with ionized molecules has a large effect. That is, in the initial ionization, these nitrogen molecules and impurities are ionized with the same probability (for example, 1%). Therefore, the ionization rate of impurities is very low only by primary ionization. However, in the subsequent molecular collision process, a charge exchange reaction with a nitrogen molecule or the like having a higher ionization energy than that of impurities is solved, and neutral impurities are ionized. At this time, the nitrogen molecule returns to the neutral molecule. Since the number of molecular collisions is about 10 ⁹ times / second at atmospheric pressure, almost 100% of the impurities not primary-ionized are ionized in a short time.

The ionization technique using soft X-ray radiation as described above is very effective especially for removing low-concentration impurities. Impurities are general gas components (nitrogen gas, oxygen gas, etc.)
When the ionization energy is low as compared with the above, and as a result the impurity concentration is low, almost 100% ionization is possible according to the present invention.

As a method of ionizing impurities, an ionization method by corona discharge has been conventionally known as described above. However, this method cannot be used for treating the air supplied to the clean room and the air supplied to the living space because ozone of a considerably high concentration is also generated at the same time.
In addition, since it utilizes the discharge phenomenon, it cannot be used for ignitable gas treatment.

On the other hand, according to the ionization method by soft X-ray irradiation according to the present invention, since neutral oxygen atoms (radicals) are not generated, ozone is not generated at all, and it is explosion-proof. There are no restrictions. Furthermore, since the ionization reaction proceeds in the entire space irradiated with soft X-rays, the ionization efficiency is higher than that by the corona discharge method, and the running cost is also lower than that by the corona discharge method.

In this way, the impurities in the air ionized by the soft X-ray emitting device 30 are recovered and removed by the ionized impurity recovery plate dust collecting electrode 31. The recovery plate 31 is composed of a plurality of conductive plate dust collecting electrodes, and these plate dust collecting electrodes are arranged substantially parallel to the air flow direction so as not to obstruct the air flow, as shown in the drawing. As will be described later, the cleaning liquids are arranged in parallel in a substantially vertical direction so that the cleaning liquid can easily flow from above to below. Further, as shown in FIG. 2, a positive high voltage is alternately applied to the plate dust collecting electrodes, and the plate dust collecting electrodes are grounded to positive impurity ions by an electric field formed between the plate dust collecting electrodes. Then, the negative impurity ions are collected and removed by the positive voltage applying plate dust collecting electrode. In the example shown in the figure, a positive high voltage is alternately applied to the plate dust collecting electrodes, but it is of course possible to apply a negative high voltage, and an electric field for adsorbing ionized impurities is applied between the plate dust collecting electrodes. Any structure can be adopted if it can be formed.

Further, an inlet 3 for supplying a cleaning liquid is provided above the dust collecting electrode 30 of the ionized impurity recovery plate.
2 is provided, and the cleaning liquid supplied from the inlet 32 slowly flows downward on the surface of the plate dust collecting electrode, and is discharged from the outlet 33 provided at the lower portion. Pure water or ordinary water can be used as the cleaning liquid, and an appropriate chemical can be used depending on the application.

As described above, the ionized impurity recovery section is kept wet, new liquid is constantly supplied, and the liquid in which the impurities are recovered is gradually discharged, whereby the absorption of the impurities from the liquid is reduced due to evaporation or saturation. Can be prevented. In addition, there is almost no increase in humidity, which is usually a problem in wet processing. This is because only the voltage application plate dust collecting electrode surface provided at a fairly wide interval is kept in a wet state, and the contact area with gas is such that the gas flows in a shower method or wet material. This is because unlike the conventional method, it is very small. As a result, no extra dehumidification treatment is required, and the running cost can be made very low.

The target air from which the impurities have been removed as described above is sent to the post-treatment unit 5 by the air flow formed by the blower unit 4. In the post-processing unit 5, it is possible to perform temperature / humidity adjustment or re-filtering processing as needed. Thus, the target air flow from which impurities have been removed is supplied into the clean room from the air flow outlet 7 of the chamber. If further normal air conditioning processing is required, it is supplied to a general air conditioner, and after air conditioning processing is supplied to the clean room.

In the above description, an embodiment in which the present invention is applied to an outside air processing air conditioner for a clean room has been described, but the present invention is not limited to the above example. In addition to the above, the present invention is also applicable to an air circulation system in a wet process area in a clean room, an outdoor air conditioner in a hospital, an exhaust air treatment from an animal house, an outdoor air conditioner for supplying an outside air to a general living room, various exhaust gas treatments, Can also be applied to.

[0036]

As described above, the apparatus for removing impurities in the air using soft X-ray irradiation according to the present invention has a very high impurity ionization efficiency and ionized impurity recovery efficiency.
Moreover, there is no generation of ozone (corona discharge method), which was a problem in the conventional technology, and the processing gas is dehumidified (conventional wet processing).
Since there is no need for, there is an excellent effect that the running cost can be very low.

[Brief description of drawings]

FIG. 1 is a schematic side view of an outside air processing air conditioner for a clean room, which is an apparatus for removing impurities in the air using soft X-ray irradiation according to the present invention.

FIG. 2 is a cross-sectional view of the outside air processing air conditioner shown in FIG.

FIG. 3 is a horizontal cross-sectional view of an impurity removal unit portion of the outside air processing air conditioner shown in FIG.

[Explanation of symbols]

 1 External Air Treatment Air Conditioner 2 Pretreatment Unit 3 Removal Unit 4 Blower Unit 5 Posttreatment Unit 6 Air Inlet 7 Air Outlet 8 Chamber 30 Soft X-ray Radiator 31 Ionized Impurity Recovery Plate Dust Collection Electrode 40 Blower

Claims (5)

[Claims] 1. A chamber capable of circulating an object air flow containing impurities from upstream to downstream, and irradiating the object air flow containing impurities contained in the chamber from upstream with soft X-rays. A soft X-ray irradiating means for removing the impurities ionized by the soft X-ray irradiating and arranged downstream of the soft X-ray irradiating means. Medium impurity removal device. 2. The removing means comprises a plurality of plate dust collecting electrodes arranged substantially parallel to the air flow direction,
The device for removing impurities in the air according to claim 1, wherein a voltage is applied to the plurality of plate dust collecting electrodes so that an electric field is formed between adjacent plate dust collecting electrodes. 3. A surface cleaning means for flowing the surface cleaning liquid to the ion adsorption surfaces of the plurality of plate dust collecting electrodes to such an extent that the concentration of impurities in the liquid does not reach a saturated state. The device for removing impurities in air according to claim 2, characterized in that. 4. The plurality of plate dust collecting electrodes are arranged substantially parallel to the air flow direction and arranged in parallel in a substantially vertical direction, and the surface cleaning liquid is placed from above the ion adsorption surface to below the ion adsorption surface. The device for removing impurities in the air according to claim 3, wherein the device is capable of flowing toward the air. 5. The filter means for removing dust contained in the air is further arranged on the upstream side of the soft X-ray irradiating means, according to any one of claims 1, 2, 3 and 4. An apparatus for removing impurities in the air according to 1.