JP2000157830A - Exhaust gas treatment method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detoxify exhaust gas containing harmful gas discharged from a process with high detoxifying efficiency in low running cost while ensuring safety. SOLUTION: In an exhaust gas treatment method and apparatus for detoxifying exhaust gas, exhaust gas containing harmful gas is brought into the gas- liquid contact with acidic electrolytic water raised in redox potential to be decomposed and absorbed and combustible gas and/or acidic gas is brought into the gas-liquid contact with reductive electrolytic water lowered in redox potential to be decomposed and absorbed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a harmful gas contained in exhaust gas discharged from, for example, an apparatus for manufacturing a semiconductor device or a liquid crystal display device, particularly chlorine, nitrogen trifluoride, chlorine trifluoride, nitrous oxide. Or acid gases such as hydrogen fluoride, silicon chloride, silicon fluoride, or silane, phosphine, diborane, TEOS, T
The present invention relates to a technique for detoxifying combustible gases such as MOP, TMOB, carbon monoxide, and ammonia.

[0002]

2. Description of the Related Art In recent years, semiconductor devices and liquid crystal display device manufacturing apparatuses have been increasing with the development of the semiconductor and electronics-related industries, and various kinds of harmful, flammable and explosive dangers are present in these manufacturing apparatuses. High gas is used. Exhaust gas discharged from these devices is not completely reacted or decomposed, and in extreme cases, most of the exhaust gas is discharged without being decomposed. Therefore, a treatment device for detoxifying the exhaust gas is indispensable.

Conventionally, in this type of exhaust gas treatment apparatus, the exhaust pipes of the respective production apparatuses are collected to form a collective pipe, and in many cases, the exhaust gas is collectively processed by a large detoxification apparatus installed outdoors. If there is, the pipe becomes long, so that there is a possibility that an accident such as a deposit may be generated in the pipe, a leak may occur due to corrosion, and a fire may occur. Therefore, recently, in order to prevent such an accident, an exhaust gas treatment device has been used by being installed as close as possible to a manufacturing device. Therefore, a small processing apparatus for indoor installation is often used.

[0004] Devices for indoor installation include a fixed adsorption type using a gas adsorption phenomenon, a combustion type using a combustion burner using methane, propane or the like as a fuel, a pyrolysis type using an electric heater, and a chemical reaction. BACKGROUND ART Exhaust gas treatment apparatuses using many methods, such as a reactive decomposition method using water and a wet method using water or a chemical solution, are used.

[0005] On the other hand, when chlorine is treated as an abatement target, since chlorine is a water-insoluble halogen-based gas having extremely low solubility in water, satisfactory absorption efficiency cannot be obtained by an absorption method using a wet scrubber. In order to increase absorption efficiency, it is common to use an alkaline solution such as sodium hydroxide.However, in a semiconductor process, contamination by an alkali metal such as sodium is extremely disliked, so it cannot be used in a wet scrubber of indoor equipment, Wastewater treatment must be performed in isolation, which is not easy. Further, even if absorbed in water, the chlorine molecules react with water, the chlorine ions results in a (Cl - ^-) with hypochlorite ions ^(ClO). Since these ions return to chlorine gas again when they are drained and are neutralized with an aqueous alkaline solution in a neutralization tank of a water treatment facility or the like, they are released, so it can be said that this method is satisfactory. Absent.

There is also a method of treating with activated carbon or an adsorbent obtained by adsorbing an alkaline chemical on activated carbon. However, since these adsorbents only physically adsorb chlorine,
After the adsorption saturation, the adsorbent is washed with water to drive off the adsorbate,
Although the wastewater is to be treated, the above-mentioned ions are eventually generated, and this method cannot be said to be an effective abatement method.

Further, the adsorbent may be incinerated, but in this case, it is more dangerous, and toxic organic chlorine compounds such as chloric acid-based harmful gas and dioxin are generated. There are also cases where the adsorbent is solidified with concrete and landfilled, but this is not essentially harmless, and the running cost is high, which is out of the question. Separately, there is also a method of converting it to harmless calcium chloride by reacting with calcium oxide at high temperature, but the equipment cost and operating cost are expensive, and the handling operation is complicated and troublesome because of handling solids and powders. There is.

Next, as a method for detoxifying nitrogen trifluoride, since it is a poorly water-soluble halogen-based gas as in the case of the above-mentioned chlorine gas, it cannot be treated only by a wet scrubber or an adsorption method, and is heated by metallic silicon or the like. There is a method of once reacting with silicon fluoride gas and trapping it with a wet scrubber or adsorbent at the later stage, but since the reactants such as silicon are consumables, they must be replenished frequently, and the running cost However, there is a disadvantage that it becomes expensive. Further, when reacting with oxides on the silicon surface, harmful nitrogen oxides are generated as by-products, which cannot be said to be complete removal. Furthermore, in the case of simultaneous treatment with another harmful gas, there are many cases where combustion treatment is carried out by a combustion type device, but all the burned nitrogen trifluoride is discharged as nitrogen oxides, and this gas is contained in water. The problem is even greater because less is melted and much is discharged as is.

Regarding the method of detoxifying chlorine trifluoride, this gas is extremely easily decomposed by water to produce chlorine, fluorine, hydrogen chloride, hydrogen fluoride and the like.
Adsorption type, thermal decomposition type, and wet type are used, but as for the chlorine gas, there is no effective detoxification method as described above, and there is still a problem that needs to be solved.

The above-mentioned chlorine, fluorine, nitrogen trifluoride, chlorine trifluoride and the like are called as a combustion supporting gas, and they explode with a combustible gas (hydrogen, silane, hydrocarbon, etc.) like oxygen. Refers to the gas that causes the reaction. As a method of detoxifying these combustible gases, a reaction in which chlorine and hydrogen are directly burned with raw gas as in the conventional hydrochloric acid synthesis can be considered. When the concentration of the reactive gas is low or mixed with another gas, as described above, for example, in the case of nitrogen trifluoride, a harmful nitrogen There is a problem that oxides are generated and must be treated in a later step.

Next, silane, phosphine, diborane,
A case in which a combustible gas such as TEOS, TMOP, TMOB, carbon monoxide, and ammonia is treated will be described. There is a dry method of treating these gases by causing a chemical reaction with the reactants.However, in the case of the amount used in a normal production line, the frequency of changing the reactants is high, and the running cost is considerably increased. Therefore, in recent years, the combustion type has become the mainstream. On combustion, they become solids of silicon oxide, phosphorus oxide and boron oxide. Therefore, there is a problem in that solids accumulate around the combustion chamber, so that frequent maintenance is required, and the production line must be frequently stopped.

In particular, as environmental concerns have increased in recent years, semiconductor manufacturers have been responsible for treating harmful gases to monitor whether or not the treatment is complete even after the treated gas leaves the factory. The tide has become a burdensome tide, and the essence of the abatement principle of the device has been questioned. Under such circumstances, if the processing is to be performed with high safety, the cost is naturally increased as described above, and if the processing is to be performed with an inexpensive apparatus, a wet scrubber must be used. In addition, there is a problem that the ability is insufficient and the use of an alkali solution using an alkali metal is required.

[0013]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and has been developed in view of the above problem. It is an object of the present invention to provide an exhaust gas treatment method and a treatment apparatus capable of performing a detoxification treatment while ensuring performance.

[0014]

According to a first aspect of the present invention, there is provided a method of treating an exhaust gas for detoxifying a harmful gas, wherein the exhaust gas containing the harmful gas is oxidized and reduced. This is an exhaust gas treatment method characterized by gas-liquid contact with acidic electrolyzed water having an increased potential to cause decomposition and absorption.

As described above, in the exhaust gas treatment method for detoxifying the harmful gas contained in the exhaust gas discharged from the process, the exhaust gas containing the harmful gas is raised by increasing the oxidation-reduction potential produced by the electrolytic water generator. Acidic electrolyzed water (hereinafter, referred to as
If it is decomposed and absorbed by gas-liquid contact with acidic water), harmful gases can be oxidized and rendered harmless, and the emission of harmful gases can be significantly reduced and safety is ensured. As a result, the exhaust gas treatment capacity can be improved. In addition, the facility cost and the running cost can be reduced as compared with the conventional various treatment methods, and the cost of the exhaust gas treatment can be reduced.

According to a second aspect of the present invention, there is provided a method for treating exhaust gas for detoxifying harmful gas, comprising the steps of:
An exhaust gas treatment method characterized in that a combustion supporting gas and / or an acidic gas is brought into gas-liquid contact with reducing electrolyzed water having a reduced oxidation-reduction potential to be decomposed and absorbed.

As described above, in the method for treating exhaust gas, which detoxifies harmful gas contained in exhaust gas discharged from the process, the exhaust gas containing a flammable gas and / or an acid gas is produced by an electrolytic water generator. If it is brought into gas-liquid contact with reducing electrolyzed water with reduced oxidation-reduction potential (hereinafter sometimes referred to as reduced water) and absorbed and decomposed, it can reduce particularly difficult-to-treat combustion-supporting gas and / or acid gas. It can be rendered harmless, the emission of harmful gas can be significantly reduced, and safety can be ensured to improve the exhaust gas treatment capacity. In addition, the facility cost and the running cost can be reduced as compared with the conventional various treatment methods, and the cost of the exhaust gas treatment can be reduced.

Next, the invention according to claim 3 of the present invention relates to a method for treating exhaust gas for detoxifying harmful gases,
An exhaust gas treatment method comprising treating the harmful gas with acid electrolyzed water in gas-liquid contact to decompose and absorb the harmful gas and reducing electrolyzed water in gas-liquid contact to decompose and absorb the harmful gas.

As described above, if the harmful gas is treated in the step of bringing it in contact with acidic water in gas-liquid to decompose and absorb it, and in the step of bringing it in contact with reduced water in gas-liquid to decompose and absorb it, The harmful gas that reacts with the acidic water can be rendered harmless, and the harmful gas that reacts with the reduced water can also be made harmless, so that any exhaust gas mixed with any harmful gas can be rendered almost completely harmless. Therefore, the emission amount of harmful gas can be remarkably reduced, safety can be ensured, and the exhaust gas treatment capacity can be improved.
In addition, the facility cost and the running cost can be reduced as compared with the conventional various treatment methods, and the cost of the exhaust gas treatment can be reduced.

In this case, as described in claim 4, the harmful gas decomposed and absorbed by the acidic electrolyzed water is silane, phosphine, diborane, TEOS, TMOP, TMOB, carbon monoxide, ammonia or two of them. The above can be a combustible gas mixed.

As described above, in the present invention, the harmful gases decomposed and absorbed by the acidic water are flammable gases such as silane, phosphine, diborane, TEOS, TMOP, TMOB, carbon monoxide, and ammonia. Even if they are present alone or in a mixed state in the exhaust gas discharged from the process, they not only have the acidity of acidic water, but also have the oxidizing properties developed due to the inclusion of radicals generated at the anode and oxygen components such as ozone. Since it is almost completely oxidatively decomposed and absorbed by the utilized oxidation reaction, harmless wastewater can be obtained.

Further, as described in claim 5, the combustion supporting gas decomposed and absorbed by the reducing electrolyzed water is chlorine, nitrogen trifluoride, chlorine trifluoride, nitrous oxide or two of these.
It can be a gas mixed with more than species. Thus, the supporting gas, which was extremely difficult to treat conventionally, is chlorine,
Nitrogen trifluoride, chlorine trifluoride, and nitrous oxide, even if each is present alone or in a mixed state in the exhaust gas discharged from the process, in the present invention, a halogen oxide-based ion, for example, ClO ^- without having to, Cl ^- ions, F ^- since it is almost completely reduced to the ions can be detoxified. Nitrous oxide is also reduced to nitrogen gas and oxygen gas and becomes non-toxic.

Further, in this case, as described in claim 6, the acidic gas decomposed and absorbed by the reducing electrolyzed water is hydrogen fluoride, silicon tetrachloride, silicon tetrafluoride, or two or more thereof. Can be used as a mixed gas. As described above, in the present invention, the acidic gas that is decomposed and absorbed by the reduced water is hydrogen fluoride, silicon chloride, or silicon fluoride, each of which is contained alone or in a mixed state in the exhaust gas discharged from the process. Even if it is present, the neutralization or hydrolysis reaction can be caused without using an alkaline chemical such as caustic soda by utilizing the high alkalinity of the reduced water, and can be rendered harmless. Therefore, it is an extremely effective exhaust gas treatment method in factories that do not like to be contaminated by alkali metals such as semiconductor processes.

Next, the invention described in claim 7 of the present invention is:
In an exhaust gas treatment device for detoxifying harmful gases, at least an electrolyzed water generator for electrolyzing water to generate acidic electrolyzed water and reducing electrolyzed water, and an acid water wet scrubber for circulating acidic electrolyzed water and absorbing harmful gases And / or a reduced water wet scrubber for circulating reducing electrolyzed water to absorb harmful gases.

According to such an apparatus, even if the harmful gas component in the exhaust gas discharged from the process is a flammable gas, a combustible gas and / or an acidic gas, the flammable gas is electrolyzed water. It is oxidatively decomposed and absorbed and made harmless by the acidic water produced in the generator. Further, the combustible gas and / or the acid gas are reduced and decomposed by the reduced water produced in the electrolyzed water generator, absorbed and made harmless. Therefore, the amount of harmful gas emissions can be significantly reduced, and the exhaust gas treatment device can hardly cause air pollution. In addition, equipment costs and running costs can be reduced as compared with conventional various treatment methods, and exhaust gas treatment can be reduced. The exhaust gas treatment device can be reduced in cost.

Hereinafter, the present invention will be described in more detail. The present inventors have found that the harmful gas components contained in the exhaust gas generated from various processes are small in the case of a single substance, and that there are many multi-component mixed systems. In view of the fact that costs are increasing, various investigations and examinations are made on processing methods and processing equipment suitable for detoxifying flammable gas, combustible gas, and acidic gas used in the semiconductor-related industry, which is particularly difficult to process. As a result of these studies, it was found that if these harmful gases were decomposed and absorbed by gas-liquid contact with acidic electrolyzed water or reducing electrolyzed water produced by an electrolyzed water generator, they could be easily made harmless, The present invention has been scrutinized and completed.

The exhaust gas targeted by the present invention is, for example, various types.
Hazardous gas contained in exhaust gas discharged from the process
, And are classified as follows based on their reactivity. First,
One is a flammable gas called silane (SiH
_Four ), Phosphine (PH_Three ), Diborane (B_Two H
₆ ), TEOS (Tetra Ethoxy Silan)
e, Si (OC_Two H_Five )_Four ), TMOP (Tri Me
thylphosphate, PO (OCH_Three )_Three ),
TMOB (Tri Methodology Boron, B
(OCH_Three )_Three ), Carbon monoxide (CO), ammonia
(NH _Three ), Etc., or two or more of these are mixed
Gas, in the case of the present invention, produced in an electrolyzed water generator
Decompose and absorb these gases with acidic electrolyzed water to make them harmless
be able to.

Here, as the acidic electrolyzed water, a strongly oxidized water having an oxidation-reduction potential of +1000 mV or more and a pH of 2.7 or less is usually used.
The optimum condition is appropriately selected depending on the flow rate and the like.

Next, the term "combustible gas" refers to a gas that reacts explosively with the combustible gas (hydrogen, silane, hydrocarbon, etc.), such as oxygen. These supporting gases, which had been considered difficult, were taken up as targets for treatment. Specifically, it is a gas containing chlorine (Cl ₂ ), nitrogen trifluoride (NF ₃ ), chlorine trifluoride (ClF ₃ ), nitrous oxide (N ₂ O), or a mixture of two or more of these. In the case of the present invention, these gases can be decomposed and absorbed by the reducing electrolyzed water produced by the electrolyzed water generator to make the gas harmless.

Here, the reducing electrolyzed water is reducing alkaline ionized water, which is usually alkaline at a pH of 11 or more and has a strong reducing power with an oxidation-reduction potential of -800 mV or less. Optimal conditions are appropriately selected depending on the type, concentration, flow rate and the like of the flammable gas.

In the present invention, the acidic gas is exemplified by hydrogen fluoride, silicon tetrachloride, silicon tetrafluoride, etc., or a gas in which two or more of these are mixed. Refers to gas that is decomposed and absorbed by

As described above, according to the present invention, even if these gases are present alone or in a mixed state in the exhaust gas discharged from the process, the alkaline water such as caustic soda is utilized by utilizing the high alkalinity of the reducing electrolyzed water. Neutralization or hydrolysis reaction can be caused without using a chemical, and detoxification can be achieved. Therefore, in the semiconductor device process, contamination by alkali metals such as soda and potash is extremely disliked, so that the effectiveness of the present invention is extremely high. Here, the combustible gas and the acid gas also have many properties in common, so that the exhaust gas containing both can be efficiently treated by bringing the reducing electrolyzed water into gas-liquid contact.

The feature of the exhaust gas treatment method of the present invention is that, for example, the reactivity of the three types of harmful gases
The reactivity of the acidic electrolyzed water and the reduced electrolyzed water produced by the electrolyzed water generator matches well, and the detoxification treatment can be performed efficiently and at low cost.

Therefore, when these are further mixed, or when the composition of the exhaust gas is not known accurately, the step of bringing the harmful gas into gas-liquid contact with acidic water to decompose and absorb the harmful gas, the step of contacting the reduced water with gas-liquid, If the detoxification process is performed by the step of decomposing and absorbing, the exhaust gas can be almost completely detoxified. The order of this treatment step may be such that after performing gas-liquid contact with the acidic water, gas-liquid contact with the reduced water is performed, or conversely, after performing gas-liquid contact with the reduced water, the gas-liquid contact with the acidic water is performed. Liquid contact may be performed. In the electrolyzed water generator,
Since acidic water and reduced water are produced in approximately the same amount at the same time, if the exhaust gas system is divided into a flammable gas system and a combustion supporting gas and / or acid gas system, the acidic water It is also possible to perform the treatment simultaneously by the treatment step and the treatment step with the reduced water.

The exhaust gas which has been subjected to the decomposition and absorption treatment by the above-mentioned exhaust gas treatment method may be discharged to the atmosphere as it is because the harmful gas content is greatly reduced. A part of the exhaust gas after the treatment can be returned to the inlet side of the treatment apparatus, or can be adsorbed by the adsorbent of the adsorber. In addition, depending on the components of the harmful gas, solid components may be generated after decomposition. In this case, the solid components may be separated by a filter or the like and subjected to a secondary treatment.

As described above, if the harmful gas contained in the exhaust gas discharged from the process is decomposed and absorbed by oxidized water or reduced water produced by the electrolyzed water generator, almost all of the harmful gas is harmless. Harmful gas emissions can be significantly reduced, and safety can be ensured to improve exhaust gas treatment capacity. In addition, the facility cost and the running cost can be reduced as compared with the conventional various treatment methods, and the cost of the exhaust gas treatment can be reduced. Further, in the semiconductor device process, the alkali gas is not used in the exhaust gas treatment method of the present invention, so that pollution is eliminated, so that the exhaust gas treatment device can be installed indoors, and clogging of pipes, which has been a problem in the case of outdoor installation, can be performed. Accident prevention such as corrosion has also become easier.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings, but the present invention is not limited to these embodiments. Here, FIG. 1 is a schematic diagram showing a configuration example of the exhaust gas treatment apparatus of the present invention.

As shown in FIG. 1, the exhaust gas treatment apparatus 1 of the present invention comprises, for example, an electrolyzed water generator 2 for electrolyzing at least water to generate acidic electrolyzed water and reducing electrolyzed water, and an acid electrolyzed water. It is composed of an acidic water wet scrubber 3 that circulates and absorbs harmful gases and / or a reduced water wet scrubber 4 that circulates reducing electrolytic water and absorbs harmful gases. FIG. 1 shows an example of a configuration in which an acidic water wet scrubber 3 and a reduced water wet scrubber 4 are connected in series.
First, a combustible gas is treated with acidic water supplied from the electrolyzed water generator 2, and then an exhaust gas treatment in which the combustible gas and / or acidic gas is treated with reduced water supplied from the electrolyzed water generator 2. The device 1 is shown.

The electrolyzed water generator 2 is connected to an anode 6 through a diaphragm 5.
And a cathode 7 are arranged, an electric decomposing apparatus of water by applying a DC voltage through the electrolyte controller 10, negative hydroxide ions to 6 side anode (OH ^-) and oxygen gas by the oxidation reaction gathered It becomes water, and the hydrogen ion concentration increases around the electrodes, and acidic oxidized water (acidic electrolyzed water, acidic water) is generated. Usually, the oxidation-reduction potential is +1000 mV or more,
Strongly oxidized water having a pH of 2.7 or less is obtained.

On the other hand, cations (H ⁺ , M
⁺ ) Are collected and hydrogen gas is generated by the reduction reaction, and the concentration of hydroxide ions increases around the electrode to generate reducing alkali ionized water (reducing electrolyzed water, reducing water), and pH 11
With the above alkalinity, it has a strong reducing power with an oxidation-reduction potential of -800 mV or less. The generated acidic water and reduced water are sent to the acidic water wet scrubber 3 and the reduced water wet scrubber 4 by the acidic water pump 8 and the reduced water pump 9, respectively.

Since the acidic water wet scrubber 3 and the reduced water wet scrubber 4 differ only in the components of the exhaust gas to be treated and the type of absorbing solution, there is no significant difference in the configuration of the equipment. Therefore, the acidic water wet scrubber 3 will be described ([ [] Is the code of the reduced water wet scrubber).

A gas-liquid contact portion 31 [41] for improving gas-liquid contact efficiency is provided in the acidic water wet scrubber 3, and acidic water [reduced water] is acidified from above the gas-liquid contact portion 31 [41]. Water is sprinkled through the water sprinkling pipe 32 [reduced water sprinkling pipe 42].
At this time, exhaust gas containing harmful gas is introduced from the lower part of the gas-liquid contact part 31 [41] through the exhaust gas introduction pipe 11, and the acidic water [reduced water] and the exhaust gas are exchanged through the gas-liquid contact part 31 [41]. Upon contact, the harmful gas in the exhaust gas is absorbed by the acidic water [reduced water] and accumulates at the bottom of the tower, and the harmful gas is discharged from the top of the tower. The acidic water [reduced water] accumulated at the bottom of the tower is sprayed again through the acidic water sprinkling pipe 32 [reduced water sprinkling pipe 42] by the acidic water [reduced water] circulation pump 33 [43].
In this way, the acidic water [reduced water] circulates and absorbs the harmful gas until it reaches a predetermined concentration, and is gradually discharged from the middle of the circulation system through the acidic water discharge pipe 35 [reduced water discharge pipe 45]. The amount of new acidic water [reduced water] corresponding to the amount of wastewater is supplied from the acidic water pump 8 [reduced water pump 9] to the acidic water supply pipe 34.
It is supplied through the [reduced water supply pipe 44].

In this case, the detoxic gas (decombustible gas) discharged from the top of the acidic water wet scrubber 3 is removed by the intermediate blower 12 into the gas-liquid contact portion 4 of the reduced water wet scrubber 4.
1 and is decomposed and absorbed by contacting the circulating reduced water.

The gas-liquid contact section 31 [41] may be brought into gas-liquid contact by a scrubber method in which exhaust gas is bubbled into the liquid using a slit plate, a perforated plate, a bubble bell plate, or the like, a spray nozzle or a dispersion plate. A method using a so-called absorption tower or a packed tower, such as a method of spraying the absorbing liquid into the exhaust gas, a method of gas-liquid exchange in a packed bed in which the packing is stacked, and the like, are all effective.

The acidic water [reduced water] that comes into contact with the exhaust gas containing the harmful gas is newly supplied from the electrolyzed water generator 2 through the supply pipe 34 [44] using the acidic water pump 8 [reduced water pump 9]. [Reduced water] may be used, or the liquid used for decomposition and absorption may be used as it is using an acidic water [reduced water] circulation pump 33 [43].

Acidic water [reduced water] wet scrubber 3 [4]
The exhaust gas that has been decomposed and absorbed by the harmful gas
Since the content of harmful gas has been greatly reduced, it may be released to the atmosphere as it is, but for completeness, a part of the treated exhaust gas may be returned to the inlet side of each wet scrubber. Alternatively, it can be adsorbed on an adsorbent of an adsorber (not shown). Activated carbon etc. are mentioned as an adsorbent. In addition, depending on the components of the harmful gas, solid components may be generated after decomposition. In such a case, the components may be separated by a filter or the like and subjected to a secondary treatment (not shown).

As another configuration example of the exhaust gas treatment apparatus of the present invention, the order of disposing the reduced water wet scrubber in series after the acidic water wet scrubber is reversed, and the acidic water wet scrubber is disposed after the reduced water wet scrubber. May be arranged in series, and may be appropriately selected according to the purpose. In the electrolyzed water generator, acid water and reduced water are simultaneously produced in approximately the same amount, so that the exhaust gas system is divided into a flammable gas system and a combustion supporting gas and / or acid gas system. It is also possible to arrange an acid-water wet scrubber and a reduced-water wet scrubber in parallel to treat the two system gases independently and simultaneously.

According to the apparatus configured as described above, the harmful gas in the exhaust gas discharged from the process is a flammable gas,
If it belongs to a supporting gas or an acidic gas, it is decomposed by an acidic water wet scrubber or a reduced water wet scrubber by acidic water or reduced water produced by an electrolyzed water generator,
It is absorbed and can make harmful gas almost completely harmless. Therefore, the amount of harmful gas emissions can be significantly reduced, and the exhaust gas treatment device can hardly cause air pollution. In addition, equipment costs and running costs can be reduced as compared with conventional various treatment methods, and exhaust gas treatment can be reduced. An exhaust gas treatment device capable of reducing costs is provided.

[0049]

EXAMPLES Next, the present invention will be described in detail with reference to examples of the present invention and comparative examples, but these do not limit the present invention. (Example 1) silane SiH ₄ 800 sccm (stan
A wet scrubber SBS-4 FU- is obtained by mixing a mixed exhaust gas of dard cubic centimeter per minute) and ammonia gas NH _{3 2} slpm (standard liter per minute) with nitrogen gas for purging by an exhaust dry pump to a flow rate of about 40 slpm. 3 (trade name, manufactured by Seiko Kakoki Co., Ltd.). The absorption water used in the wet scrubber was tap water, which was used as a continuous electrolytic water generator. A. 1. W-020 [trade name, manufactured by Nippon Intec Co., Ltd., acidic water maximum capacity: pH;
4 or less, ORP value: -1150 ± 20 mV, amount of acidic water:
(2 L / min) electrolyzed acidic ionized water having a pH of 2.0 was flowed at a flow rate of 2 L / min, and the water after gas-liquid contact was drained in one pass without circulation. As a result of measuring the SiH ₄ concentration and the NH ₃ concentration in the exhaust gas at the outlet of the wet scrubber,
All were below the detection limit of 1 ppm.

(Comparative Example 1) Exhaust gas treatment was performed under the same conditions as in Example 1 except that the tap water used in the wet scrubber for absorbing exhaust gas of Example 1 was used as ordinary water. As a result, the silane gas concentration in the exhaust gas at the outlet of the wet scrubber was about 3 ppm. From the above test, it can be seen that the silane gas reacts with the acidic water to be oxidized and almost completely decomposed.

(Example 2) 100 sccm of chlorine (Cl) discharged from an aluminum dry etching apparatus
₂ ) and a mixed exhaust gas of 30 sccm boron chloride (BCl ₃ ), mixed with nitrogen gas for purging by a dry pump for exhaust to a flow rate of about 40 slpm, and wet scrubber S
Treated with BS-4 FU-3 (supra). The absorption water used in the wet scrubber was tap water, which was used as a continuous electrolytic water generator.
A. W-020 [trade name, manufactured by Nippon Intec Co., Ltd., maximum capacity of alkaline ionized water: pH: 11.0 or more, ORP
Value: -1150 ± 20 mV, amount of alkaline ionized water: 2 L
/ Min) pH of alkaline ionized water electrolyzed at 12.0
Was flowed at a flow rate of 2 L / min, and the water after gas-liquid contact was drained in one pass without circulation.

The Cl ₂ concentration in the exhaust gas at the outlet of the wet scrubber,
As a result of measuring the concentration of BCl _{3 and the} concentration of HCl which may be generated by decomposition thereof, they were all 0 ppm. Also, hypochlorous acid (ClO ⁻ ) in the wastewater at this time
As a result of measuring the concentration with a total residual chlorine concentration meter, the detection limit was 1
ppm.

(Comparative Example 2) The absorbed water of Example 2 was adjusted to pH 12
Exhaust gas treatment was performed under the same conditions as in Example 2 except that caustic soda water was used. As a result, the chlorine concentration at the outlet of the wet scrubber drainage was about 50 ppm (initial 0 ppm). As a result of the above test, in the present invention, the treated chlorine was dissolved in water, and no hypochlorite was detected at all. Therefore, it is presumed that all the chlorine was converted to chloride ions.

Example 3 1000 diluted with nitrogen gas
ppm of hydrogen fluoride was treated with the same apparatus as in Example 1 (wet scrubber manufactured by Seiko Kakoki Co., Ltd., SBS-4 FU-3). The absorption water used in the wet scrubber was tap water, which was used as a continuous electrolytic water generator. A. PH of alkaline ionized water electrolyzed with W-020 (supra);
The flow was conducted at an in flow rate, and the water after gas-liquid contact was drained in one pass without circulation. HF in exhaust gas at wet scrubber outlet
As a result of measuring the concentration, it was 1 ppm.

(Comparative Example 3) Exhaust gas treatment was performed under the same conditions as in Example 3 except that neutral pure water was used as the absorbed water in Example 3. As a result, the HF concentration in the wet scrubber exhaust was 3 ppm. As a result of the above test, it is understood that HF can be efficiently treated by using the alkali ion water.

Example 4 An exhaust gas treatment apparatus was constructed in which an acid-water wet scrubber and a reduced water wet scrubber were connected in series. Here, 800 sccm of silane gas (SiH ₄ ), 100 sccm of chlorine (Cl ₂ ) and 30 sccm of chloride were used. Nitrogen gas for purging is mixed with the mixed exhaust gas of boron by a dry pump for exhausting the mixed gas to a flow rate of about 250 slpm, and a wet scrubber with an acidic water SBS-4 FU-3 is used.
(See above). As the absorption water used in the acidic water wet scrubber, tap water was used as a continuous electrolyzed water generator. A. W-02
The mixed exhaust gas was treated at a flow rate of 2 L / min with an acidic ionized water having a pH of 2.0 (electrolyzed at 0 (described above)). Subsequently, the reduced water wet scrubber SBS-4 FU
-3 (supra). The absorption water used in the wet scrubber was tap water, which was used as a continuous electrolytic water generator. A. W-020
The alkaline ionized water having a pH of 12.0, which was electrolyzed as described above, was flowed at a flow rate of 2 L / min, and the water after gas-liquid contact was drained in one pass without circulation.

SiH in the exhaust at the outlet of the acidic water wet scrubber
₄ As a result of measuring the concentration, it was confirmed that the concentration was less than the detection limit of 1 ppm, and almost all the silane gas was decomposed and absorbed. Further, chlorine and boron chloride in the exhaust gas at the outlet of the reduced water wet scrubber and H which may be generated by decomposition thereof
As a result of measuring the Cl concentration, all were 0 ppm.
Further, the concentration of hypochlorous acid (ClO ⁻ ) in the waste water at this time was measured by a total residual chlorine concentration meter, and as a result, the detection limit was 1 ppm.
Was less than. As a result of the above test, it was found that the mixed exhaust gas can be efficiently treated in the present invention by connecting the acidic water wet scrubber and the reduced water wet scrubber in series.

The present invention is not limited to the above embodiment. The above embodiment is an exemplification, and has substantially the same configuration as the technical idea described in the scope of the claims of the present invention. It is included in the technical scope of the invention.

For example, the exhaust gas treatment method and the treatment apparatus of the present invention are not applied only to the above-described semiconductor process and the like. It goes without saying that the present invention can be applied to a process of generating a harmful gas that can be rendered harmless by electrolytic ionized water. Also, the wet scrubber according to the present invention,
It is not bound by its name. The present invention is within the scope of the present invention as long as it absorbs and decomposes exhaust gas in a wet manner, and it goes without saying that the present invention is within the scope of the present invention even if the name is a packed tower, an absorption tower, or the like.

[0060]

As described above, according to the present invention, the harmful gas contained in the exhaust gas discharged from the process is decomposed and absorbed by acidic water or reduced water produced by the electrolytic water generator. Almost all of the gas can be reduced and made harmless, the emission of harmful gas can be significantly reduced, and safety can be ensured to improve the exhaust gas treatment capacity. In addition, the facility cost and the running cost can be reduced as compared with the conventional various treatment methods, and the cost of the exhaust gas treatment can be reduced. Furthermore, in the semiconductor process, the exhaust gas treatment method of the present invention does not use an alkali metal, so that there is no pollution, so that the exhaust gas treatment device can be installed indoors, and clogging and corrosion of piping, which have been a problem in the case of outdoor installation. It has also become easier to prevent such accidents.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of an exhaust gas treatment device of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Exhaust gas processing apparatus, 2 ... Electrolyzed water generator, 3 ... Acidic water wet scrubber, 4 ... Reduced water wet scrubber, 5 ... Diaphragm,
6 ... Anode, 7 ... Cathode, 8 ... Acid water pump, 9 ... Reduced water pump, 10 ... Electrolysis controller, 11 ... Exhaust gas introduction pipe, 12
... Intermediate blower, 31, 41 ... Gas-liquid contact part, 32 ... Acid water spray pipe, 33 ... Acid water circulation pump, 34 ... Acid water supply pipe, 35 ... Acid water discharge pipe, 42 ... Reduced water spray pipe, 43 ...
Reduced water circulation pump, 44: reduced water supply pipe, 45: reduced water discharge pipe.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) B01D 53/68 B01D 53/34 134A C02F 1/46 F term (reference) 4D002 AA08 AA13 AA18 AA22 AA23 AA26 AA27 AA40 AB01 AC10 BA02 BA04 BA05 BA06 BA08 CA01 CA07 CA13 DA41 DA70 EA02 GA01 GA02 GB01 GB02 GB09 GB20 HA01 HA10 4D020 AA07 AA10 BA23 BA30 CB08 CB25 CC01 CC06 CC11 CD03 DA02 DA03 DB01 DB03 DB08 DB20 4D061 DA08 DA10 DC19 DC14 DC14 DC19 EB37 FA06 FA11 GA22 GA23

Claims (7)

[Claims] An exhaust gas treatment method for detoxifying a harmful gas, wherein the exhaust gas containing the harmful gas is decomposed and absorbed by gas-liquid contact with acidic electrolyzed water having an increased oxidation-reduction potential. Method. 2. A method for treating exhaust gas for detoxifying harmful gases, wherein a combustible gas and / or an acid gas is brought into gas-liquid contact with reducing electrolyzed water having a reduced oxidation-reduction potential to be decomposed and absorbed. Exhaust gas treatment method. 3. A method of treating an exhaust gas for detoxifying a harmful gas, wherein the harmful gas is decomposed and absorbed by bringing the harmful gas into gas-liquid contact with acidic electrolyzed water, and is decomposed and absorbed by bringing the harmful gas into gas-liquid contact with reducing electrolyzed water. And an exhaust gas treatment method. 4. The harmful gas decomposed and absorbed by the acidic electrolyzed water is silane, phosphine, diborane, TEOS, TOS
4. The exhaust gas treatment method according to claim 1, wherein MOP, TMOB, carbon monoxide, ammonia, or a combustible gas containing at least two of them. 5. The combustion supporting gas decomposed and absorbed by the reducing electrolyzed water is chlorine, nitrogen trifluoride, chlorine trifluoride, nitrous oxide or a gas containing two or more of these mixed. The exhaust gas treatment method according to claim 2 or 3, wherein: 6. The acidic gas decomposed and absorbed by the reducing electrolyzed water is hydrogen fluoride, silicon tetrachloride, silicon tetrafluoride, or a gas in which two or more of these are mixed. The exhaust gas treatment method according to claim 2 or 3, wherein 7. An exhaust gas treatment apparatus for detoxifying harmful gases, wherein an electrolyzed water generator for electrolyzing at least water to generate acidic electrolyzed water and reducing electrolyzed water and circulating the acidic electrolyzed water to absorb harmful gases. An exhaust gas treatment device comprising an acidic water wet scrubber and / or a reduced water wet scrubber that circulates reducing electrolytic water and absorbs harmful gases.