JP2014188497A - Detoxification treatment apparatus and detoxification treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detoxification treatment apparatus which decomposes and eliminates a harmful gas component in a processed gas with high efficiency and achieves downsizing, and to provide a detoxification treatment method.SOLUTION: A detoxification treatment apparatus 1 includes: a solution storage tank 2 which stores a solution in which a harmful gas component in a processed gas dissolves; a gas introduction hole 3 which is provided at the bottom part side of the solution storage tank 2 and introduces the processed gas into the solution as bubbles P; a processed gas supply passage 5 which supplies the processed gas to the gas introduction hole 3; plasma generation means 6 which makes the processed gas into plasma in the gas introduction hole 3; and a gas exhaust port 4 which is provided at the upper part side of the solution storage tank 2 and exhausts a gas component, from which a harmful component is eliminated, to the outer side of the solution storage tank 2.

Description

  The present invention relates to a detoxification treatment apparatus and a detoxification treatment method for detoxifying harmful gas components in a gas to be treated.

As refrigerant gas or semiconductor manufacturing process gas, chlorofluorocarbon (= CFC / CCl ₂ F ₂ , C ₂ F ₅ Cl, etc.), hydrochlorofluorocarbon (= HCFC / CHClF ₂ , CH ₃ CClF ₂ etc.), hydrofluorocarbon (= HFC) / CH ₂ F ₂ , C ₂ HF ₅ etc.), halon (CBrClF ₂ , CBrF ₃ etc.), perfluorocarbon (CF ₄ , C ₂ F ₆ etc.), CCl ₄ , CH ₃ Cl, SF ₆ , NF ₃ etc. Widely used.

  While these gases are industrially important gases, they are also a cause substance of ozone layer destruction and global warming, and toxic gases, so that it is required to suppress atmospheric emissions as much as possible. For example, when a car, a cooler, or the like is discarded due to aging or the like, the used refrigerant gas is collected and detoxified.

  In addition, these gases are characterized by containing halogen atoms (F, Cl, Br, etc.), and have a relatively large interatomic bond energy and are stable molecules. Therefore, in the detoxification treatment, it is necessary to decompose by applying energy such as combustion, high temperature, plasma or light, and to chemically react halogen atoms with water or an alkali compound.

  Specifically, for example, in the case of process exhaust gas from a semiconductor manufacturing apparatus, a dry-type abatement apparatus (catalyst + adsorbent), a combustion or plasma decomposition apparatus (decomposition unit) and a wet scrubber apparatus may be used. It is used. Here, the wet scrubber device is a device that sprays sprayed water onto the gas to be treated, such as cooling of the gas heated to a high temperature in the decomposition section, removing unstable water-soluble substances such as halogen atoms generated by decomposition, etc. Used for the purpose.

By the way, generally, when detoxifying extremely stable molecules such as CF ₄ , C ₂ F ₆ , and SF ₆ , the latter means (that is, a decomposition device and Combined use with wet scrubber equipment).

However, unstable halogen atoms generated in the decomposition part easily react with carbon or the like present in the vicinity, so that if the distance between the decomposition part and the wet scrubber part is large, CF ₄ , C ₂ F ₆ , SF _{6 and the} like were easily regenerated, and there was a problem that the expected removal efficiency could not be obtained. As countermeasures, as disclosed in Patent Documents 1 to 3, a configuration in which the distance between the disassembling part and the wet scrubber part is reported is reported.

  Specifically, Patent Document 1 is an invention related to a combustion exhaust gas treatment apparatus that decomposes and removes silane and fluorinated substances in exhaust gas of a semiconductor manufacturing apparatus. This Patent Document 1 shows a configuration in which a decomposition unit that decomposes a component to be removed in a combustion furnace of about 1000 ° C. and a wet scrubber unit that sprays mist-like water from a shower nozzle are provided in the same apparatus. Yes.

  Patent Document 2 is an invention relating to an atmospheric pressure plasma gas processing apparatus that decomposes and removes silane and PFC discharged from an industrial process. This Patent Document 2 shows a configuration in which a decomposition unit that decomposes a component to be removed by an atmospheric pressure plasma generation unit and a post-stage wet scrubber that processes a water-soluble component and a solid component that have been decomposed are provided in the same apparatus. ing.

FIG. 4 shows a conventional detoxification processing apparatus 101 that performs a decomposition process and a wet scrubber process in the same apparatus. As in Patent Document 1 and Patent Document 2, a conventional separate did in device degradation process and the wet scrubber treatment, by a configuration that can be processed in the same apparatus as shown in FIG. 4, CF _4, etc. Applicants' research has also shown that it has the effect of preventing the by-product formation. On the other hand, since the above-mentioned combustion part and atmospheric pressure plasma part become high temperature near 1000 degreeC, there was a limit in making a wet scrubber approach, and there was a subject that an apparatus will be enlarged.

  Patent Document 3 is an invention that aims to stabilize the active species generated in the plasma portion before deactivation in consideration of the lifetime of the active species. In this Patent Document 3, a plasma generator and a porous calcium oxide agent-filled cylinder are arranged in series, and a detoxification device for venting a gas to be treated under a reduced pressure of about 100 to 5000 Pa, and a plasma generator to be covered. A detoxification method is disclosed in which a processing gas is converted into plasma and an unstable fluorine component decomposed and generated in a plasma portion is removed by a chemical reaction with porous calcium oxide.

  In the method disclosed in Patent Document 3, since a treatment under a reduced pressure atmosphere is important, a porous calcium oxide agent is used instead of a wet scrubber. However, the method disclosed in Patent Document 3 still has a problem that a dry pump with a large displacement is necessary and a problem that it takes time to replace the porous calcium oxide agent.

JP 2013-015232 A Republished WO2008 / 093442 Japanese Patent No. 4895612

  The present invention has been made in view of the above circumstances, and provides a detoxification processing apparatus and a detoxification processing method that can decompose and remove harmful gas components in a gas to be treated with high efficiency and can be downsized. The issue is to provide.

  As described above, in order to maintain a high detoxification efficiency and suppress the production of by-products, it is effective to bring the decomposition part of the harmful gas component and the wet scrubber part close to each other. Accordingly, as a result of intensive studies, the inventors of the present application have found a method of collecting (removing) the gas to be processed through a solution (water or alkaline solution) while maintaining the plasma state, and completed the present invention. I let you.

That is, the present invention has the following configuration.
The invention according to claim 1 is an apparatus for removing and detoxifying the harmful gas component from the gas to be treated containing the harmful gas component,
A solution storage tank for storing a solution for dissolving harmful gas components in the gas to be treated in an airtight internal space;
A gas introduction hole provided on the bottom side of the solution storage tank and introducing the gas to be treated into the solution as bubbles;
A processing gas supply path for supplying the processing gas to the gas introduction hole;
Plasma generating means for converting the gas to be processed into plasma through the gas introduction hole;
It is a detoxification processing apparatus provided with the gas discharge port provided in the upper part side of the said solution storage tank, and discharging | emitting the gas component from which the said harmful component was removed to the outer side of the said solution storage tank.

  The invention according to claim 2 is the detoxification processing apparatus according to claim 1, wherein a hole diameter of the gas introduction hole is in a range of 0.01 to 2.0 mm.

The invention according to claim 3 is characterized in that the plasma generating means has a high voltage power source, a high voltage electrode, and a ground electrode.
3. The detoxification processing apparatus according to claim 1, wherein the high voltage electrode and the ground electrode are disposed to face each other with the gas introduction hole interposed therebetween.

In the invention according to claim 4, the high-voltage power supply is a high-frequency power supply,
The frequency of the high frequency power supply is f (unit Hz), and the radius of the gas introduction hole is r (unit μm), the relationship of the following formula (1) is satisfied. It is a detoxification processing apparatus of description.
f <1 × 10 ¹⁴ × r ⁻² (1)

The invention according to claim 5 is a method of removing the harmful gas component from the gas to be treated containing the harmful gas component and detoxifying the gas.
A first step of supplying a gas to be processed into a narrow space, and bringing the gas to be processed into a plasma state in the space;
A second step of allowing the harmful gas component in the gas to be treated to pass through the solution in a bubble state while keeping the harmful gas component in the plasma state, and dissolving the harmful gas component in the solution;
A third step of removing the gaseous component from which the harmful component has been removed from the solution.

According to the present invention, since the gas to be processed is converted into plasma in the gas introduction hole by the plasma generating means, the harmful gas component in the gas to be processed can be reliably decomposed and converted into plasma with a small amount of energy. .
Further, the gas introduction hole is provided on the bottom side of the solution storage tank, and the plasma-treated gas is immediately introduced into the solution in the solution storage tank as bubbles, so that the plasma-generated harmful gas component Can suppress generation of by-products. Therefore, harmful gas components in the gas to be treated can be dissolved in the solution and reliably removed.
Furthermore, since the gas introduction hole for decomposing the gas to be treated and the solution storage tank for removing the harmful components in the gas to be treated are provided close to each other, the harmful gas components in the gas to be treated can be decomposed and removed with high efficiency. In addition, a detoxification processing apparatus and a detoxification processing method that can be reduced in size can be provided.

It is a block diagram which shows the detoxification processing apparatus which is 1st Embodiment to which this invention is applied. It is a block diagram which shows the detoxification processing apparatus which is 2nd Embodiment to which this invention is applied. It is a block diagram which shows the detoxification processing apparatus which is 3rd Embodiment to which this invention is applied. It is a block diagram which shows the conventional detoxification processing apparatus.

Hereinafter, a detoxification processing apparatus according to an embodiment to which the present invention is applied will be described in detail with reference to the drawings together with a detoxification processing method using the same.
In addition, in the drawings used in the following description, in order to make the features easy to understand, there are cases where the portions that become the features are enlarged for the sake of convenience, and the dimensional ratios of the respective components are not always the same as the actual ones. Absent.

<First Embodiment>
First, the configuration of a detoxification processing apparatus according to an embodiment to which the present invention is applied will be described with reference to FIG. As shown in FIG. 1, the detoxification processing apparatus 1 of the present embodiment is an apparatus that removes harmful gas components from the gas to be treated containing harmful gas components and renders them harmless. A gas introduction hole 3 provided in the bottom surface 2 a of the solution storage tank 2, a gas discharge port 4 provided in the top surface 2 b of the solution storage tank 2, and a process for supplying a gas to be processed to the gas introduction hole 3 A gas supply path 5 and plasma generating means 6 for converting the gas to be processed into plasma through the gas introduction hole 3 are schematically configured.

  The detoxification processing apparatus 1 of the present embodiment is intended for processing a gas to be processed that contains harmful gas components. The gas to be treated is not particularly limited. Specifically, the exhaust gas from a dry pump that evacuates a semiconductor manufacturing apparatus such as a plasma etching apparatus, a used refrigerant filled container such as an automobile or an air conditioner. Residual gas, residual gas in a used high-pressure gas container, and the like.

  Although the harmful gas component in the gas to be treated is not particularly limited, specifically, for example, perfluorocarbon gas, hydrofluorocarbon gas, and by-products obtained by decomposition of these contained in the exhaust gas from the dry pump. Gas etc. are mentioned. Moreover, chlorofluorocarbon, hydrochlorofluorocarbon, etc. contained in the residual gas in a used refrigerant | coolant filling container are mentioned as a noxious gas component.

  Note that the gas to be treated may contain components other than harmful gas components. Specific examples of the other components include nitrogen gas for dilution added in the dry pump section, nitrogen gas for corrosion prevention, and the like.

  The solution storage tank 2 is a cylindrical container that has an airtight internal space and stores a solution that dissolves harmful gas components in the gas to be processed in the internal space. As the solution storage tank 2, as shown in FIG. 1, a cylindrical container composed of a bottom surface 2a, an upper surface 2b, and an outer peripheral surface 2c can be exemplified, but it is not particularly limited to this configuration. . For example, the bottom surface 2a and the top surface 2b shown in FIG. 1 are configured as flat surfaces, but may be configured as curved surfaces.

The size (volume) of the solution storage tank 2 is not particularly limited, and can be appropriately selected depending on the processing amount of the gas to be processed, the desired processing capacity, the size of the installation space, and the like.
Moreover, the material of the solution storage tank 2 will not be specifically limited if it is a material which has corrosion resistance. Preferable materials include, for example, corrosion resistant metals such as SUS316L, Hastelloy, titanium, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE). ) And the like.

The solution stored in the internal space of the solution storage tank 2 is not particularly limited as long as it is a liquid capable of dissolving harmful gas components contained in the gas to be processed. That is, it is preferable to select appropriately according to the kind of harmful gas component. In particular, when the harmful gas component contains any one or more of a fluorine atom (F), a chlorine atom (Cl), a bromine atom (Br), and an iodine atom (I), water (H ₂ O), etc. It is preferable to select an alkaline solution such as a neutral solution, barium hydroxide aqueous solution, sodium hydrogen carbonate solution, calcium hydroxide aqueous solution, and aqueous ammonia.

  The storage amount of the solution in the internal space of the solution storage tank 2 is not particularly limited, and can be appropriately selected according to the processing amount of the gas to be processed, the volume of the solution storage tank, and the like. . Here, in the solution storage tank 2, it is preferable that the gas layer 2B is provided above the solution layer 2A made of a solution as shown in FIG. . By providing the gas layer 2B in the internal space of the dissolution reservoir 2, the gas component that has passed through the solution layer 2A can be retained in the gas layer 2B before being discharged to the outside of the dissolution reservoir 2. For this reason, even when the removal of the harmful gas component in the gas to be treated in the solution layer 2A is insufficient, it can be prevented from being discharged directly to the outside of the dissolution reservoir 2.

  The gas introduction hole 3 is an opening having a narrow space provided in the bottom surface 2 a of the solution storage tank 2 in order to introduce the gas to be processed into the solution in the solution storage tank 2 as bubbles P. The shape of the portion of the gas introduction hole 3 facing the solution layer 2A in the solution storage tank 2 (that is, the shape of the opening surface) is not particularly limited. In order to obtain P, a circular shape is preferable. In addition, when a member constituting the bottom surface 2a has a certain thickness, the gas introduction hole 3 including the space in the through hole penetrating the bottom surface 2a is referred to. Furthermore, in the case where openings are provided through the insulating plate 7 and the electrodes 6A and 6B so as to be continuous with the through-holes penetrating the bottom surface 2a, the gas introduction holes including the spaces in these openings are also included. Three.

  Moreover, the hole diameter (diameter) of the gas introduction hole 3 can select the optimal apparatus conditions in consideration of the behavior of the bubbles P in the solution, the gas-liquid interface reaction, and the plasma discharge conditions. Specifically, the diameter of the gas introduction hole 3 is preferably in the range of 0.01 to 2.0 mm, and more preferably in the range of 0.1 to 0.5 mm.

  Here, if the hole diameter of the gas introduction hole 3 is less than 0.01 mm, as is apparent from Paschen's law, it is required to make the power supply voltage very high, which is not preferable because the device design becomes difficult. On the other hand, if the hole diameter exceeds 2.0 mm, the surface tension is insufficient and the solution drips into the gas introduction hole 3, and not only the solution cannot be held, but also the electrode portions 6A and 6B get wet and leak. Since there exists a possibility that an electrode may deteriorate, it is not preferable.

  As shown in FIG. 1, since the gas introduction hole 3 is provided at the center of the bottom surface 2a of the solution storage tank 2, the behavior of the bubbles P in the solution is stable, and the entire region in the height direction of the solution layer 2A Can sufficiently cause a gas-liquid interface reaction. Here, the position of the gas introduction hole 3 is an example, and is not limited to this as long as the gas to be treated can be introduced into the solution in the solution storage tank 2 as the bubble P. . Specifically, the position of the gas introduction hole 3 can be provided up to a height at which the solution layer 2A exists. However, the gas introduction hole 3 may be provided on the lower side of the solution storage tank 2 in order to secure a moving distance in the solution. Preferably, it is more preferably provided on the bottom surface.

  Moreover, although the example which provided one gas introduction hole 3 in the bottom face 2a is shown by FIG. 1, it is not limited to this, You may provide multiple. By providing a plurality of gas introduction holes 3, it is possible to improve the efficiency of the detoxification process of the gas to be processed. When a plurality of gas introduction holes 3 are provided, it is preferable to appropriately select a layout (interval, arrangement) in consideration of the behavior of the bubbles P in the solution, the efficiency of the gas-liquid interface reaction, and the like.

  The gas discharge port 4 is provided on the upper surface 2 b of the solution storage tank 2 in order to discharge the detoxified gas component after removing harmful gas components contained in the gas to be processed to the outside of the solution storage tank 2. Exhaust vent. As described above, since the gas introduction hole 3 is provided on the lower side of the solution storage tank 2 and the gas discharge port 3 is provided on the upper side, the detoxification treatment apparatus 1 allows the gas to be treated to be bubbled from the gas introduction hole 3. In this state, the gas component introduced into the solution in the solution storage tank 2 and the harmful gas component removed from the gas discharge port 4 can be discharged to the outside of the solution storage tank 2.

  In addition, the position of the gas discharge port 4 shown in FIG. 1 is an example, and is not limited to this as long as the gas component detoxified can be discharged to the outside of the solution storage tank 2. . The position of the gas discharge port 4 is specifically the upper side of the solution storage tank 2 and is preferably provided at a position communicating with the gas layer 2 </ b> B in the solution storage tank 2. Moreover, the magnitude | size of the gas exhaust port 4 and the installation number of the gas exhaust ports 4 are not specifically limited, You may select suitably. Furthermore, the gas discharge port 4 may be provided with an on-off valve.

  The gas supply path 5 to be processed is provided from the source of the gas to be processed to the gas introduction hole 3 in order to supply the gas to be processed to the gas introduction hole 3. As a result, the gas to be processed generated at the generation source of the gas to be processed is sent to the gas introduction hole 3 through the gas supply path 5 to be processed, and is stored in the solution storage tank 2 through the gas introduction hole 3. Introduced into the solution.

  As illustrated in FIG. 1, the gas supply path 5 to be processed is schematically configured from a gas supply pipe 5A to be processed and a gas storage tank 5B to be processed.

  The to-be-treated gas supply pipe 5A is provided between a to-be-treated gas supply source (not shown) and the to-be-treated gas storage tank 5B, and the to-be-treated gas is supplied from the to-be-treated gas generation source into the to-be-treated gas storage tank 5B. It is a route to supply to. The material of the gas supply pipe 5A to be processed is not particularly limited as long as it is a material that does not corrode by the gas to be processed. Specifically, for example, corrosion resistant metals such as SUS316L, Hastelloy, titanium, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE). ) And the like can be used.

  Further, the gas supply pipe 5A is provided with a flow rate adjusting valve 5a so that the flow rate of the gas to be processed supplied to the gas storage tank 5B or the gas introduction hole 3 can be adjusted. Here, regarding the flow rate of the gas to be treated, the optimum apparatus conditions can be selected in consideration of the behavior of bubbles in water, gas-liquid interface reaction, and plasma discharge conditions. Specifically, for example, it is preferable to adjust so that the flow rate of the gas to be processed per gas introduction hole 3 is in the range of 1 to 1000 ml / min. Taking an etching apparatus used for semiconductor manufacturing as an example, the process gas flow rate is several tens of ml / min, and at least 1000 ml / min of gas is exhausted downstream of a pump that evacuates the process chamber. In other words, if the flow rate of gas to be processed per gas introduction hole is less than 1 ml / min, it means that it is necessary to provide 1,000 or more gas introduction holes, which leads to an increase in the size of the apparatus and the complexity of the plasma generation means. I will. On the other hand, when processing a gas to be processed exceeding 1000 ml / min with one gas introduction hole, even if the diameter of the gas introduction hole is 0.2 mm, the average flow velocity of the gas to be processed passing through the gas introduction hole is 500 m / min. Since it exceeds s, it becomes difficult to make a stable plasma discharge and sufficient gas-liquid contact.

  As shown in FIG. 1, the gas storage tank 5B is provided below the solution storage tank 2 and between the gas introduction hole 3 and the gas supply pipe 5A. Further, the space in the gas storage tank 5B and the space in the gas introduction hole 3 are communicated with each other. Thereby, the to-be-processed gas stored in the to-be-processed gas storage tank 5B can be introduce | transduced into the solution layer 2A (in solution) from the downward direction of the solution storage tank 2 via the gas introduction hole 3. FIG.

  The gas storage tank 5B is a cylindrical container that has an airtight internal space and stores the gas to be processed in the internal space. In addition, the shape of the gas storage tank 5B to be treated is not particularly limited, but as illustrated in FIG. 1, it is preferable to have a shape that shares the bottom surface 2a of the solution storage tank 2 as the top surface. By adopting such a configuration, for example, even when a plurality of gas introduction holes 3 are provided in the bottom surface 2 a of the solution storage tank 2, the gas to be treated is supplied to all these gas introduction holes 3 at the same time. Can do.

  The size (volume) of the gas storage tank 5B is not particularly limited, and can be appropriately selected depending on the processing amount of the gas to be processed, the desired processing capacity, the size of the installation space, and the like. . Moreover, the material of the to-be-processed gas storage tank 5B will not be specifically limited if it is a material which has corrosion resistance. Preferable materials include, for example, corrosion resistant metals such as SUS316L, Hastelloy, titanium, polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl copolymer (PFA), tetrafluoroethylene / ethylene copolymer (ETFE). ) And the like can be used.

In addition, the structure of the to-be-processed gas supply path | route 5 is an example, Comprising: It is not limited to this. For example, a water tank (not shown) may be provided in the gas supply pipe 5A to be processed, and the gas to be processed may be bubbled in the water tank and then supplied to the gas introduction hole 3. Accordingly, since the gas to be treated can be humidified before being supplied to the gas introduction hole 3, the hydrogen atoms contained in the water (H ₂ O) accompanied by bubbling when the gas is converted into plasma by the gas introduction hole 3. However, it can easily collide with halogen atoms contained in the gas to be treated, and the removal efficiency of impurities can be increased.

  Further, the gas supply path 5 to be processed may be configured by only the gas supply pipe 5A to be processed. By omitting the gas storage tank 5B and connecting the tip of the gas supply pipe 5A directly to the gas introduction hole 3, the detoxification apparatus 1 can be further downsized.

  The plasma generating means 6 is a plasma apparatus for converting the gas to be processed into plasma in the gas introduction hole 3. In the detoxification processing apparatus 1 of the present embodiment, as shown in FIG. 1, the plasma generating means is schematically configured to include a high voltage electrode 6A, a ground electrode 6B, and a high voltage power source 6C.

  As shown in FIG. 1, the high voltage electrode 6 </ b> A and the installation electrode 6 </ b> B are disposed to face each other with the gas introduction hole 3 interposed therebetween. By performing discharge between the high voltage electrode 6 </ b> A and the installation electrode 6 </ b> B arranged in this way, the gas to be processed can be turned into plasma in the gas introduction hole 3. In other words, the gas introduction hole 3 becomes a plasma discharge part, and harmful gas components in the gas to be treated are decomposed in a narrow space of the gas introduction hole 3.

In addition, the surfaces of the high voltage electrode 6A and the installation electrode 6B are protected by an insulating member made of a material such as quartz, alumina (Al ₂ O ₃ ), or ceramics, except for a portion serving as a discharge portion. Specifically, as shown in FIG. 1, the high-voltage electrode 6 </ b> A and the installation electrode 6 </ b> B are sandwiched from above and below by a pair of insulating plates 7, 7, and are only covered in the gas introduction hole 3. The electrode is exposed. Thereby, the to-be-processed gas in the to-be-processed gas storage tank 5B and electrodes 6A and 6B do not contact, but only the to-be-processed gas supplied to the gas introduction hole 3 is made into plasma. As described above, only the narrow space of the gas introduction hole 3 is used as a plasma discharge portion, and the region for plasma treatment is limited. Therefore, the harmful gas component in the gas to be treated supplied to the gas introduction hole 3 is reliably plasma. State.

  The type of the high voltage power supply 6C is not particularly limited, and either a direct current power supply or an alternating current power supply can be used. Further, the electrode shape of the high voltage electrode 6A and the installation electrode 6B may be selected according to the type of the high voltage power supply 6C, or a matching circuit may be provided.

  The output of the high voltage power supply 6C varies depending on conditions such as the power supply frequency, the distance between the electrodes and the flow rate of the gas to be processed, but the output per gas introduction hole 3 (that is, the discharge part) is set in the range of 1W to 500W. It is desirable to do. Here, if the power output is too low, it is not preferable because sufficient decomposition efficiency cannot be obtained. On the other hand, if the power output is too high, the discharge part (that is, the gas introduction hole 3) becomes high temperature, which is not preferable because the electrode is deteriorated and the solution is excessively evaporated.

By the way, when the harmful gas component contained in the gas to be treated is a particularly difficult-to-decompose component such as perfluorocarbon, high-density plasma is generated to decompose the hardly-decomposable harmful gas component. Need to do. Specifically, such high-density plasma is required to have a plasma density of 1 × 10 ⁹ (pieces / cm ³ ) or more. It is also known that the higher the frequency of the power supply, the smaller the depth (skin depth) at which electromagnetic waves can penetrate into the plasma, and the higher the plasma density, the more prominent the effect is. .

Therefore, in the detoxification processing apparatus 1 of the present embodiment, when the high voltage power source 6C is a high frequency power source and high density plasma having a plasma density of 1 × 10 ⁹ (pieces / cm ³ ) or more is required, the frequency Is a frequency f that satisfies the relationship of the following formula (1), where f is a unit Hz and the diameter of the gas introduction hole 3 is r (unit μm).
f <1 × 10 ¹⁴ × r ⁻² (1)

By setting the power supply frequency of the high voltage power supply 6C to the frequency f satisfying the relationship of the above formula (1), the plasma density is 1 × with respect to the hole diameter (that is, the interelectrode distance of the discharge part) r of the gas introduction hole 3. Even if high-density plasma of 10 ⁹ (pieces / cm ³ ) or more is generated, sufficient electromagnetic waves can be continuously supplied.

  In the detoxification processing apparatus 1 of the present embodiment, the gas introduction hole 3 constitutes a decomposition part for harmful gas components, and the solution storage tank 2 constitutes a recovery (removal) part for harmful gas components.

Next, the detoxification processing method of this embodiment using the above-described detoxification processing apparatus 1 will be described with reference to FIG.
The detoxification treatment method of the present embodiment includes a stage (first step) in which a gas to be treated is supplied to a narrow space and the gas to be treated is brought into a plasma state in the space (first step), and harmful gas components in the gas to be treated are plasma. A state in which the harmful gas component is dissolved in the solution by passing through the solution in a bubble state (second step), and a step of removing the gaseous component from which the harmful component has been removed (second step). 3 steps).

  Specifically, first, a gas to be processed generated by a gas source to be processed (not shown) is supplied to the gas introduction hole 3 via the gas supply path 5 to be processed. At this time, by adjusting the opening degree of the flow rate adjusting valve 5a, the flow rate of the gas to be processed per gas introduction hole 3 is adjusted to be in the range of 1 to 1000 ml / min.

  At the same time as the supply of the gas to be processed is started, the high-voltage power supply 6C of the plasma generating means 6 is turned on, and the high-voltage electrode 6A and the installation electrode 6B arranged opposite to each other with the gas introduction hole 3 interposed therebetween. Discharge. Thereby, the gas introduction hole 3 becomes a plasma discharge part, and harmful gas components in the gas to be treated are decomposed in the narrow space of the gas introduction hole 3 (that is, the gas to be treated is in a plasma state). At this time, the output of the high-voltage power supply 6C is set in the range of 1 W to 500 W per gas introduction hole 3 (that is, the discharge part).

  Next, the harmful gas component in the gas to be treated is introduced into the solution in the solution storage tank 2B from the gas introduction hole 3 in a bubble state while being in a plasma state. The gas to be treated introduced into the solution is in gas-liquid contact with the solution. And while repeating the gas-liquid contact and ascending in the solution layer 2A, the harmful gas component in the gas to be treated is dissolved in the solution, so the harmful gas component in the gas to be treated is abolished. Detoxified.

  Here, since the harmful gas component is immediately introduced into the solution in a plasma state, the decomposed harmful gas component is effectively absorbed into the solution without recombination.

  Next, the gas component from which harmful components have been removed by passing through the solution layer 2A (that is, the gas to be treated that has been rendered harmless) is discharged into the gas layer 2B provided above the solution layer 2A. The gas layer 2B is configured. Next, the gas layer 2 </ b> B including the gas component from which harmful components have been removed is discharged from the gas discharge port 4 to the outside of the solution storage tank 2.

  As described above, according to the detoxification processing apparatus 1 and the detoxification processing method of the present embodiment, the plasma generating means 6 converts the gas to be processed into plasma in the gas introduction hole 3. Gas components can be reliably decomposed into small portions and turned into plasma. Further, the gas introduction hole 3 is provided in the bottom surface 2a of the solution storage tank 2, and the gas to be treated can be immediately introduced into the solution in the solution storage tank 2 as a bubble P. The harmful gas components in the gas to be treated can be dissolved in the solution and reliably removed without generating by-products and the like.

  According to the detoxification treatment apparatus 1 and the detoxification treatment method of the present embodiment, a gas introduction hole 3 (decomposition part) for decomposing the gas to be treated and a solution storage tank 2 (removal, Since the recovery unit) is installed in the vicinity, harmful gas components in the gas to be treated can be decomposed and removed with high efficiency, and the size can be reduced.

<Second Embodiment>
Next, a second embodiment to which the present invention is applied will be described. In the present embodiment, the detoxification processing apparatus 1 and the detoxification processing method of the first embodiment have different configurations. Therefore, the detoxification processing apparatus and the detoxification processing method of this embodiment will be described with reference to FIG. Therefore, regarding the detoxification processing apparatus and the detoxification processing method of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 2, the detoxification processing device 21 of this embodiment has a configuration in which a detoxification performance monitoring monitor 8 and a gas flow rate controller 9 are added to the configuration of the detoxification device 1 of the first embodiment. It has become.

  The detoxification performance monitor 8 is provided in the solution storage tank 2 in order to monitor the concentration of harmful gas components contained in the gas after detoxification (in the gas). Specifically, the abatement performance monitoring monitor 8 continuously or intermittently measures and analyzes components in the gas layer 2B in the solution storage tank 2, and the concentration of harmful gas components remaining in the gas layer 2B is a reference. Monitor whether it is below the value. This makes it possible to determine in real time whether the output of the high voltage power supply 6C is sufficient or insufficient. Furthermore, it is possible to prevent release of a gas component that is not sufficiently detoxified to the outside of the apparatus.

  Since the abatement performance monitoring monitor 8 is electrically connected to the high voltage power supply 6C via the line TL1, an output signal is sent from the abatement performance monitoring monitor 8 to the high voltage power supply 6C via the line TL1. Can do. According to the detoxification processing apparatus 21 of the present embodiment, the detoxification process of the gas to be processed is reliably performed by controlling the output of the high voltage power supply 6C in conjunction with the instruction value of the detoxification performance monitoring monitor 8. At the same time, it is possible to optimize power consumption.

  The gas flow rate controller 9 is provided in the processing gas supply path 5 in order to stabilize the flow rate of the processing gas in the gas introduction hole 3. The position of the gas flow rate controller 9 is not particularly limited, but is preferably provided in the gas supply pipe 5A to be processed, and more preferably provided on the primary side (upstream side) of the flow rate adjustment valve 5a.

  Further, as shown in FIG. 2, the gas flow rate controller 9 is electrically connected to the abatement performance monitoring monitor 8 via a line TL2, and receives a control signal from the abatement performance monitoring monitor 8 via the line TL2. be able to. According to the detoxification processing apparatus 21 of the present embodiment, the removal performance monitoring monitor 8 and the gas flow rate controller 9 can be linked to adjust the flow rate of the gas to be treated in the gas introduction hole 3. Harmful performance can be stabilized.

<Third Embodiment>
Next, a third embodiment to which the present invention is applied will be described. In the present embodiment, the detoxification processing apparatus 1 and the detoxification processing method of the first embodiment have different configurations. Therefore, the detoxification processing apparatus and the detoxification processing method of this embodiment will be described with reference to FIG. Therefore, regarding the detoxification processing apparatus and the detoxification processing method of the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  By the way, in a detoxification processing apparatus, a part of harmful gas component dissolves in a solution by performing a detoxification process. For example, when perfluorocarbon is detoxified, fluorine dissolves in the solution. When the concentration of dissolved fluorine in the solution increases, the ability of the solution to treat harmful gas components decreases. Therefore, it is necessary to periodically replace the entire amount of the solution or to replace it by small amounts as appropriate.

  Therefore, as shown in FIG. 3, the detoxification treatment device 31 of the present embodiment replaces the solution storage tank 2 constituting the detoxification device 1 of the first embodiment with a solution addition port 10 </ b> A and a solution discharge port 10 </ b> B. The solution storage tank 32, the harmful component dissolved concentration monitoring monitor 11, and the solution addition amount controller 12 are provided. As a result, it is possible to appropriately replace a solution having a reduced ability to treat harmful gas components little by little.

  The solution storage tank 32 has a solution addition port 10A for supplying a new solution to the solution storage tank 32 in order to update the solution whose processing capacity has been reduced by dissolving harmful gas components little by little, and the processing capacity is reduced. A solution discharge port 10B for discharging a part of the solution from the solution storage tank 32 is provided. Here, the solution addition port 10A is provided on the lower side of the side surface 32c of the solution storage tank 32, and the solution discharge port 10B is provided on the upper side of the side surface 32c. A solution supply path 13 is connected to the solution addition port 10A.

  In addition, by providing the solution discharge port 10B, the internal space of the solution storage tank 32 is a solution layer 32A less than the height at which the solution discharge port 10B is provided, and is more than the height at which the solution discharge port 10B is provided. Layer 32B is formed.

  The harmful component dissolved concentration monitoring monitor 11 is provided in the solution storage tank 32 in order to monitor the concentration of the harmful component dissolved in the solution. Specifically, the harmful component dissolved concentration monitor 11 measures and analyzes the components in the liquid layer 32 </ b> A in the solution storage tank 32 continuously or intermittently. This makes it possible to determine the solution replacement time.

  The solution addition amount controller 12 is provided in the solution supply path 13. Further, as shown in FIG. 3, the solution addition amount controller 12 is electrically connected to the harmful component dissolved concentration monitor monitor 11 via the line TL3, and is controlled from the harmful component dissolved concentration monitor monitor 11 via the line TL3. A signal can be received. According to the detoxification processing apparatus 31 of the present embodiment, since the harmful component dissolved concentration monitoring monitor 11 and the solution addition amount controller 12 linked thereto are provided, the solution in the solution storage tank 32 is gradually added at any time. Even in the case of replacement, appropriate replacement can be performed.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the detoxification processing apparatus 21 of the second embodiment described above, the gas discharge port 4 may be provided with a gas discharge path switching means that operates in conjunction with the indicated value of the removal performance monitoring monitor 8. Thereby, when it is detected by the abatement performance monitoring monitor 8 that the harmful gas component concentration remaining in the gas layer 2B after the detoxification process exceeds the reference value, the gas discharge path can be switched. Release of gas components to the outside of the apparatus can be reliably prevented.

  Moreover, it is good also as a structure which provides one or more detoxification processing apparatuses in the downstream (secondary side) of the detoxification processing apparatuses 1,21,31 of 1st-3rd embodiment mentioned above. In this way, two or more detoxification processing apparatuses are connected in series, and the gas (gas) detoxified by the preceding detoxification processing apparatus is used as a new gas to be treated, and again the subsequent detoxification processing apparatus. By performing the detoxification treatment by the above, it is possible to more reliably remove harmful gas components contained in the gas to be treated. Note that any of the above-described detoxification processing apparatuses 1, 21 and 31 according to the first to third embodiments may be applied as the detoxification processing apparatuses at the front stage and the rear stage.

  In addition, in the said 1st-3rd embodiment of this invention, although the solution storage tanks 2 and 32 and the to-be-processed gas storage tank 5B were demonstrated by the separate member, it was not limited to this. Alternatively, the solution storage tanks 2 and 32 and the gas storage tank 5B may be integrated with one member.

  Here, correspondence between the case where the solution storage tank and the gas storage tank to be processed are configured as separate members and the case where the solution storage tank and the gas storage tank are configured as one member will be described by taking the harmless treatment apparatus 1 of the first embodiment as an example. Specifically, first, a container such as a water tank in which the solution storage tank 2 and the gas storage tank 5B are integrated is defined as a harmless treatment apparatus main body (hereinafter simply referred to as “main body”). Inside the main body, a partition member is provided to make the internal space of the main body into two spaces divided vertically, and this partition member corresponds to the bottom surface 2 a of the solution storage tank 2.

  Of the internal space of the main body, an upper space is provided with a solution layer and a gas layer, and this upper space corresponds to the internal space of the solution storage tank 2. On the other hand, the lower space becomes a gas layer to be processed, and this lower space corresponds to the internal space of the gas storage tank 5B. And the hole is provided in the said partition member so that upper space and lower space may be connected, and this hole respond | corresponds to the gas introduction hole 3 of the detoxification processing apparatus 1 of 1st Embodiment. In addition, a gas inlet is provided on the lower side of the main body, and this gas inlet corresponds to a connecting portion between the gas storage tank 5B and the gas supply pipe 5A in the first embodiment. Further, a gas discharge port corresponding to the gas discharge port 4 in the first embodiment is provided on the upper side of the main body.

  Therefore, in the detoxification processing apparatus having the detoxification processing apparatus main body in which the solution storage tank 2 and the processing gas storage tank 5B are integrated, the processing target gas is supplied from the gas supply port to the lower part of the main body. Hazardous gas components in the gas are removed. And the to-be-processed gas made harmless is discharged | emitted from the gas discharge port provided in the upper part of the main body to the outer side of the main body.

Specific examples are shown below.
Example 1
An experiment for decomposing nitrogen trifluoride was performed using a detoxification apparatus having the configuration shown in FIG. 1 and using a gas containing 1% of nitrogen trifluoride (NF 3) in helium (He) as a gas to be processed. In addition, the diameter of the gas introduction hole of the detoxification processing apparatus was 0.3 mm, and the power source for discharge was a 24V DC power source. The solution was pure water, and the height from the gas introduction hole to the water surface was 20 cm.

The plasma state was good when discharged under the conditions of the flow rate of the gas to be treated: 200 sccm and the power output: 50 W, and the decomposition efficiency of nitrogen trifluoride was 41%.
Here, the decomposition efficiency was calculated by the following equation.
(Decomposition efficiency) = 100 − [(flow rate of component to be decomposed after passing through the solution) ÷ (flow rate of component to be decomposed through the gas introduction hole)] × 100

On the other hand, the decomposition efficiencies when the flow rate of the gas to be treated was 100 sccm and 500 sccm were 49% and 27%, respectively. As a result, it was confirmed that the decomposition efficiency decreases as the flow rate of the gas to be processed increases.
Similarly, the decomposition efficiencies when the power supply output was 30 W and 500 W while the flow rate of the gas to be processed was 200 sccm were 25% and 60%, respectively. However, under the condition where the power output is 500 W, the amount of water decreases with the decomposition treatment time due to the temperature rise of the discharge part, and it is necessary to add water appropriately.

  In addition, when the gas to be treated was discharged under the conditions of 200 sccm and power output: 50 W, the detoxified gas that passed through the solution was recovered, and the gas recovered from the gas introduction hole was again introduced under the same conditions. The decomposition efficiency was 55%. This result means that the two-step detoxification process has improved the total decomposition efficiency to 73% (41% in the case of only one step) and is very effective in improving the removal efficiency. It was confirmed.

(Example 2)
Using the detoxification processing apparatus having the configuration shown in FIG. 1, an experiment was conducted in which a gas containing 0.5% ethane hexafluoride (C ₂ F ₆ ) in argon was used as a gas to be processed and ethane hexafluoride was decomposed. It was. The diameter of the gas introduction hole was 0.2 mm, and the power source for discharge was a 2 MHz high frequency power source. The solution was pure water, and the height from the gas introduction hole to the water surface was 10 cm.

  The plasma state was good when discharged under the conditions of the flow rate of the gas to be treated: 100 sccm and the power output: 100 W, and the decomposition efficiency of hexafluoroethane was 30%.

  Here, when the gas to be treated is bubbled in a water tank not shown in FIG. 1 and is introduced into the gas introduction hole in a humidified state, the decomposition efficiency of hexafluoroethane under the same conditions described above becomes 45%. It was. Furthermore, the decomposition efficiency was 55% under the condition where the power output was 300 W.

(Example 3)
Using the detoxification treatment apparatus having the configuration shown in FIG. 1, an experiment was conducted in which methyl chloride was decomposed using a gas containing 10% of methyl chloride (CH ₃ Cl) in nitrogen as the gas to be treated. The diameter of the gas introduction hole was 0.05 mm, and the power source for discharge was a 2.45 GHz microwave power source. In addition, when supplying microwaves, waveguides were used because there are many power transmission losses due to the skin effect when feeding with copper wires. The solution was pure water, and the height from the gas introduction hole to the water surface was 10 cm.

  The plasma state was good when discharged under the conditions of the flow rate of the gas to be treated: 50 sccm and the power output: 300 W, and the decomposition efficiency of methyl chloride was 75%.

  Here, only the diameter of the gas introduction hole was changed, and the change in decomposition efficiency was confirmed. When the diameter of the gas introduction hole was 0.1 mm and 0.2 mm, the decomposition efficiency was 70 to 75%. On the other hand, when the diameter of the gas introduction hole was increased to 0.4 mm and 0.5 mm, the decomposition efficiency gradually decreased, and the decomposition efficiency was 60% under the condition of 0.5 mm.

1, 21, 31 ... Detoxification processing device 2, 32 ... Solution storage tank 2a, 32a ... Bottom 2b, 32b ... Top 3 ... Gas inlet 4 ... Gas outlet 5 ... Process gas supply means 5A ... Process gas supply pipe 5B ... Process gas supply tank 6 ... Plasma generation means 6A ... High voltage electrode 6B ... Ground electrode 6C ... High voltage power supply 7 ... Insulating plate (insulating member)
8 ... Detoxification performance monitoring monitor 9 ... Gas flow rate controller 10A ... Solution addition port 10B ... Solution discharge port 11 ... Hazardous component dissolved concentration monitoring monitor 12 ... Solution addition amount controller

Claims (5)

An apparatus for removing the harmful gas component from the gas to be treated containing the harmful gas component to render it harmless,
A solution storage tank for storing a solution for dissolving harmful gas components in the gas to be treated in an airtight internal space;
A gas introduction hole provided on the bottom side of the solution storage tank and introducing the gas to be treated into the solution as bubbles;
A processing gas supply path for supplying the processing gas to the gas introduction hole;
Plasma generating means for converting the gas to be processed into plasma through the gas introduction hole;
A detoxification treatment apparatus comprising: a gas discharge port provided on an upper side of the solution storage tank and configured to discharge a gas component from which the harmful components have been removed to the outside of the solution storage tank.   The harmless treatment apparatus according to claim 1, wherein a hole diameter of the gas introduction hole is in a range of 0.01 to 2.0 mm. The plasma generating means has a high voltage power source, a high voltage electrode, and a ground electrode,
The harmless treatment apparatus according to claim 1 or 2, wherein the high-voltage electrode and the ground electrode are disposed to face each other with the gas introduction hole interposed therebetween. The high-voltage power supply is a high-frequency power supply;
The frequency of the high frequency power supply is f (unit Hz), and the diameter of the gas introduction hole is r (unit μm), the relationship of the following formula (1) is satisfied. Detoxification processing apparatus as described.
f <1 × 10 ¹⁴ × r ⁻² (1) A method of removing the harmful gas component from the gas to be treated containing the harmful gas component and detoxifying the gas,
A first step of supplying a gas to be processed into a narrow space, and bringing the gas to be processed into a plasma state in the space;
A second step of allowing the harmful gas component in the gas to be treated to pass through the solution in a bubble state while keeping the harmful gas component in the plasma state, and dissolving the harmful gas component in the solution;
A third step of removing the gaseous component from which the harmful component has been removed from the solution;

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