Plasma scrubber for large-capacity gas treatment

Abstract

A plasma scrubber for large-capacity gas treatment, according to one embodiment of the present invention, comprises: a first electrode having a first discharge space extending in one direction therein; and a second electrode which is disposed in the longitudinal direction from the first electrode, and which has, therein, a second discharge space that is connected to the first discharge space and extends in the longitudinal direction, wherein an opening through which a treatment gas flows can be provided at a longitudinal end of the first electrode.

Description

Plasma scrubber for large-volume gas treatment

[0001] The present invention relates to a plasma scrubber for decomposing a treatment gas containing pollutants, and more particularly, to a plasma scrubber for large-capacity gas treatment.

[0002] According to known sources, technologies such as arc plasma, microwave plasma, capacitively coupled plasma, and inductively coupled plasma are used to induce high-temperature reactions or create high-temperature environments using plasma. These technologies each have their own advantages and disadvantages, as well as structural differences in the reactors used to generate plasma.

[0003] The semiconductor industry emits a variety of pollutants, including non-biodegradable gases. Due to the industry's rapid growth, semiconductor production volumes are continuously increasing. Consequently, the volume of exhaust gases requiring treatment is also increasing.

[0004] To treat indestructible gases or other pollutants, a high-temperature environment of over 2000K is required. To treat pollutants, this high-temperature environment must be created by burning fuel or by forming a high-temperature environment through plasma discharge.

[0005] Conventional plasma scrubbers have a standardized processing flow rate of 100 to 150 liters / min, making it difficult to process large volumes of waste gas.

[0006] One aspect of the present invention is to provide a plasma scrubber for large-capacity gas treatment capable of treating a large amount of pollutants.

[0007] A plasma scrubber for large-capacity gas processing according to one embodiment of the present invention includes a first electrode having a first discharge space extending in one direction therein, and a second electrode arranged longitudinally from the first electrode and having a second discharge space extending longitudinally therein, connected to the first discharge space, and wherein an opening through which a processing gas flows may be provided at a longitudinal end of the first electrode.

[0008] The first discharge space includes a throttle section having a smaller cross-sectional area than the surrounding area, and the throttle section can extend from the first discharge space to the second discharge space.

[0009] The first discharge space may have a variable inner diameter and include an upstream step connected to the throttle section.

[0010] The inner diameter of the above-mentioned upstream step portion may gradually decrease as it moves toward the downstream.

[0011] The first electrode includes a shield gas injection unit that injects shield gas into the first discharge space, and the shield gas injection unit can be located upstream of the upstream step unit.

[0012] A circulation region that induces a circulation flow is formed inside the first electrode, and the circulation region can be located upstream of the upstream step portion.

[0013] A blocking protrusion protruding inward toward the center of the first electrode may be formed on the upper portion of the above-mentioned upstream step.

[0014] The second electrode may have a changeable inner diameter and a downstream step portion connected to the throttle section may be formed.

[0015] The second electrode includes a shield gas injection unit that injects shield gas into the second discharge space, and the shield gas injection unit may be located downstream of the downstream step unit.

[0016] The inner diameter of the above downstream step portion may gradually increase as it moves toward the outlet.

[0017] On the upstream side of the above-mentioned upstream step portion, a first additional step portion connecting a portion with a cross-sectional area larger than that of the above-mentioned upstream step portion and the above-mentioned upstream step portion may be formed.

[0018] On the downstream side of the above downstream step portion, a second additional step portion may be formed that connects a portion with a larger cross-sectional area than the above downstream step portion to the above downstream step portion.

[0019] It may further include a discharge gas supply unit through which discharge gas is supplied between the first electrode and the second electrode.

[0020] The first electrode is provided with a protruding supply pipe that protrudes toward the inside of the first electrode and injects a processing gas, and the protruding supply pipe can extend in the longitudinal direction of the first electrode.

[0021] The first electrode includes a shield gas injection unit that injects shield gas into the first discharge space, and the shield gas injection unit may be located outside the protruding supply pipe.

[0022] A guide pipe for delivering a processing gas to the first electrode is connected to the upstream side of the first electrode, and a swirler for forming a rotating flow may be installed in the guide pipe.

[0023] A plasma scrubber for large-capacity gas processing according to one embodiment of the present invention may further include a reaction promoting material supply unit that supplies a reaction promoting material that induces oxidation or reduction to the first discharge space or the second discharge space.

[0024] The inner wall of the first electrode and the inner wall of the second electrode may be formed as a replaceable structure.

[0025] A plasma scrubber for large-volume gas processing according to one embodiment of the present invention is capable of rapidly processing large volumes of processing gas, since an opening is formed at the longitudinal end of the first electrode through which processing gas flows. In addition, a first throttle section is formed in the first discharge space and the second discharge space, so that the processing gas is concentrated in the area where the arc is located, thereby improving the decomposition efficiency of the processing gas.

[0026] FIG. 1 is a cross-sectional view illustrating a plasma scrubber according to a first embodiment of the present invention.

[0027] Figure 2 is a drawing illustrating a circulation area according to the first embodiment of the present invention.

[0028] Figure 3 is a cross-sectional view of a discharge gas supply unit according to the first embodiment of the present invention.

[0029] FIG. 4 is a cross-sectional view illustrating a plasma scrubber according to a first modified example of the first embodiment of the present invention.

[0030] FIG. 5 is a cross-sectional view illustrating a plasma scrubber according to a second modified example of the first embodiment of the present invention.

[0031] FIG. 6 is a cross-sectional view illustrating a plasma scrubber according to a second embodiment of the present invention.

[0032] Figure 7 is a perspective view illustrating a swirler according to a second embodiment of the present invention.

[0033] FIG. 8 is a cross-sectional view illustrating a plasma scrubber according to a first modified example of the second embodiment of the present invention.

[0034] FIG. 9 is a cross-sectional view illustrating a plasma scrubber according to a second modified example of the second embodiment of the present invention.

[0035] Fig. 10 is a cross-sectional view illustrating a plasma scrubber according to a third embodiment of the present invention.

[0036] Fig. 11 is a cross-sectional view illustrating a plasma scrubber according to a fourth embodiment of the present invention.

[0037] Fig. 12 is a cross-sectional view illustrating a plasma scrubber according to a fifth embodiment of the present invention.

[0038] Figure 13 is a drawing illustrating a circulation area according to the fifth embodiment of the present invention.

[0039] The present invention is susceptible to various modifications and embodiments. Specific embodiments are illustrated and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, but rather to encompass all modifications, equivalents, and alternatives falling within the spirit and technical scope of the present invention.

[0040] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In the present invention, it should be understood that the terms "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0041] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Please note that, where possible, identical components are represented by identical reference numerals throughout the drawings. Furthermore, detailed descriptions of well-known functions and configurations that may obscure the gist of the present invention will be omitted. For the same reason, some components in the attached drawings are exaggerated, omitted, or schematically depicted.

[0042] Below, a plasma scrubber according to a first embodiment of the present invention is described.

[0043] FIG. 1 is a cross-sectional view illustrating a plasma scrubber according to a first embodiment of the present invention, FIG. 2 is a drawing illustrating a circulation area according to the first embodiment of the present invention, and FIG. 3 is a cross-sectional view illustrating a discharge gas supply unit according to the first embodiment of the present invention.

[0044] Referring to FIGS. 1 to 3, the plasma scrubber (101) according to the present embodiment thermally decomposes a processing gas containing contaminants using high-temperature arc plasma. Here, the processing gas may contain various types of contaminants, such as perfluorinated compounds, PFCs, and CF4, generated during a semiconductor manufacturing process.

[0045] The plasma scrubber (100) may include a first electrode (120), a second electrode (130), a discharge gas supply unit (140), an opening (129), and an outlet (134).

[0046] The first electrode (120) is formed in a tube shape, and an opening (129) through which a processing gas flows is formed at one longitudinal end thereof, and the other longitudinal end thereof can be connected to a second electrode (130). A first discharge space (DS1) extending in the longitudinal direction of the first electrode (120) is formed inside the first electrode (120).

[0047] A guide tube (110) for delivering a processing gas is connected to an opening (129) formed on the upstream side of the first electrode (120), and the guide tube (110) can be coupled to the first electrode (120) via an insulating member (115). Meanwhile, an insulating member (118) can also be arranged on the downstream side of the first electrode (120), and the insulating member can insulate the first electrode (120) and the discharge gas supply unit (140).

[0048] A power source is connected to the first electrode (120), and a driving voltage can be applied. Here, the driving voltage can be a voltage sufficient to form an arc (AC1). The power source can be an AC power source or a DC power source.

[0049] A first cooling unit (125) that receives cooling water may be formed inside the wall surface of the first electrode (120). Cooling water may be continuously supplied and discharged to the first cooling unit (125).

[0050] A throttle section (TH1) having a smaller cross-sectional area than the surrounding area is formed in the first discharge space (DS1), and the throttle section (TH1) can be formed by extending from the inside of the first electrode (120) to the inside of the second electrode (130).

[0051] The first arc point (AP1) may be located upstream of the throttle section (TH1), and the second arc point (AP2) may be located downstream of the throttle section (TH1), so that the arc (AC1) may be formed to penetrate the throttle section (TH1).

[0052] When the throttle section (TH1) is formed, the processing gas can be efficiently thermally decomposed while moving through the center of the plasma scrubber (101) heated to a high temperature by the arc (AC1).

[0053] The first electrode (120) has an upstream step (121) formed with a changing inner diameter and connected to the throttle section (TH1). The upstream step (121) connects the throttle section (TH1) to an expanded portion, and the expanded portion refers to a section having a larger cross-sectional area than the throttle section (TH1). The upstream step (121) may be formed so that the cross-sectional area gradually decreases toward the downstream side. The upstream step (121) may include an inclined surface inclined with respect to the longitudinal direction of the first electrode (120).

[0054] A shield gas injection unit (124) for injecting shield gas into the first discharge space (DS1) may be formed in the first electrode (120), and the shield gas injection unit (124) may be located upstream of the upstream step unit (121). The shield gas may be composed of air, nitrogen, an inert gas, etc. In addition, the shield gas may include a reaction accelerator that assists oxidation or reduction, and the reaction accelerator may be composed of various substances such as steam, water, urea water, ammonia, etc.

[0055] A plurality of shield gas injection units (124) may be spaced apart from each other in the circumferential direction on the inner wall of the first electrode (120). The shield gas injection units (124) are connected to a shield gas passage (123) to receive shield gas, and the shield gas passage (123) may be formed to extend in the circumferential direction of the first electrode (120). A shield gas supply pipe (128) may be connected to the shield gas passage (123).

[0056] When shield gas is injected from the shield gas injection unit (124), the flow moving along the inner wall of the first electrode (120) moves toward the inner side of the first electrode (120), and a circulation area (SA1) that induces a circulation flow may be formed between the upstream step portion (121) and the shield gas injection unit (124). In the circulation area (SA1), a reverse flow moving from downstream to upstream may be formed in a portion adjacent to the wall surface of the first electrode (120). The circulation area (SA1) is located upstream of the upstream step portion (121).

[0057] In this way, when a circulation area (SA1) is formed by the shield gas injection section (124) and the upstream step section (121), the first arc point (AP1) located upstream can maintain a stable position in the longitudinal direction without moving downstream.

[0058] In addition, as illustrated in FIG. 4, a shield gas injection unit (138) may be formed downstream of the downstream step portion (131) in the second electrode (130), and the shield gas injection unit (138) may be connected to a shield gas passage (137).

[0059] In addition, as shown in FIG. 5, the shield gas injection part (124) may not be formed on the first electrode (120), and the shield gas injection part (138) may be formed only on the second electrode (130).

[0060] Meanwhile, the shield gas injection unit (124) can generate rotational force by injecting shield gas in an eccentric direction with respect to the center of the first electrode (120). Accordingly, the first arc point (AP1) can rotate along the inner wall of the first electrode (120) by the shield gas, and when the first arc point (AP1) rotates, the inner wall of the first electrode (120) can be prevented from being excessively etched due to the concentration of the arc point.

[0061] Meanwhile, the second electrode (130) is formed in a tube shape, and an outlet (134) through which a decomposed processing gas and a plasma jet are sprayed can be formed at one end in the longitudinal direction. A second discharge space (DS2) extending in the longitudinal direction of the second electrode (130) is formed inside the second electrode (130).

[0062] The second electrode (130) may be grounded, and a second cooling unit (135) containing cooling water may be formed inside the wall surface of the second electrode (130). Cooling water may be continuously supplied and discharged to the second cooling unit (135).

[0063] The above-described throttle section (TH1) extends into the interior of the second electrode (130), and a downstream step portion (131) connected to the throttle section (TH1) may be formed inside the second electrode (130). The downstream step portion (131) connects the throttle section (TH1) and an expanded portion. The downstream step portion (131) may be formed so that the cross-sectional area gradually increases as it goes toward the outlet (134). The downstream step portion (131) may include a sloped surface inclined with respect to the throttle section (TH1).

[0064] A discharge gas supply unit (140) for injecting discharge gas is formed between the first electrode (120) and the second electrode (130). The discharge gas supply unit (140) can be coupled to the first electrode (120) via an insulating member (118).

[0065] In addition, as illustrated in FIG. 3, the discharge gas supply unit (140) may be formed of an insulator and may include a discharge gas distribution passage (143) extending in the circumferential direction and a plurality of discharge gas injection holes (144) connected to the discharge gas distribution passage (143). A discharge gas supply pipe (148) may be connected to the distribution passage (143). In addition, the discharge gas may include a reaction promoting substance that assists oxidation or reduction, and the reaction promoting substance may be formed of various substances such as steam, water, urea water, and ammonia.

[0066] The discharge gas injection hole (144) may be connected in an eccentric direction with respect to the center of the discharge gas supply unit (140) so as to induce a rotational flow. The discharge gas may be composed of air, nitrogen, an inert gas, etc.

[0067] When voltage is applied to the first electrode (120) and the second electrode (130), an arc (AC1) is generated, and the arc (AC1) is extended in length by the discharge gas and can move to the upstream step (121) and the downstream step (131). The first arc point (AP1) located in the upstream step (121) can maintain a stable position without moving to the throttle section (TH1) due to the recirculation area.

[0068] Additionally, the second arc point (AP2) located on the downstream side may be located at the downstream step (131) or may move downstream of the downstream step (131). The first arc point (AP1) may be rotated by shield gas, and the second arc point (AP2) may be rotated by discharge gas.

[0069] As described above, according to the present embodiment, an opening (129) through which a processing gas flows is formed at a longitudinal end of the first electrode (120), and a large amount of the processing gas can be heated to a high temperature and decomposed while passing through the throttle section (TH1) where the arc (AC1) is located. In addition, since the first arc point (AP1) is located upstream of the throttle section (TH1), and the second arc point (AP2) is located downstream of the throttle section (TH1), the length of the arc (AC1) can be easily controlled by changing the design of the throttle section (TH1).

[0070] Below, a plasma scrubber according to a second embodiment of the present invention is described.

[0071] FIG. 6 is a cross-sectional view illustrating a plasma scrubber according to a second embodiment of the present invention, and FIG. 7 is a perspective view illustrating a swirler according to the second embodiment of the present invention.

[0072] Referring to FIGS. 6 and 7, the plasma scrubber (102) according to the second embodiment has the same structure as the plasma scrubber according to the first embodiment described above, except for the reaction accelerating material supply unit (112) and the swirler (150), and therefore, a duplicate description of the same configuration is omitted.

[0073] A reaction accelerator supply unit (112) for injecting a reaction accelerator that helps oxidation or reduction into the internal space may be installed in the guide tube (110). The reaction accelerator may be composed of various substances such as steam, water, urea solution, ammonia, etc. The reaction accelerator may be composed of a gas or a liquid. The reaction accelerator supply unit (112) may be formed as a bar that crosses the internal space of the guide tube (110), and a plurality of injection holes (112a) may be formed in the reaction accelerator supply unit (112). The reaction accelerator supply unit (112) may be located in the guide tube (110), and may be formed inside the first electrode (120) as illustrated in FIG. 8, and may be formed inside the second electrode (130) as illustrated in FIG. 9. Accordingly, the reaction accelerating material supply unit (112) may supply the reaction accelerating material to the first discharge space (DS1) or to the second discharge space (DS2).

[0074] Meanwhile, a swirler (150) for inducing a rotational flow may be installed in the guide pipe (110). The swirler (150) may include an outer support pipe (151), an inner pillar (152), and a guide vane (153). The guide vane (153) may include a first portion (153a) extending in the longitudinal direction of the guide pipe (110) and a second portion (153b) inclined with respect to the longitudinal direction of the guide pipe (110). Here, the first portion (153a) may be located on the upstream side, and the second portion (153b) may be located on the downstream side.

[0075] The outer end of the guide vane (153) may be fixed to the outer support pipe (151), and the inner end of the guide vane (153) may be fixed to the inner pillar (152). In addition, the longitudinal direction of the guide vane (153) may be extended in an eccentric direction with respect to the direction toward the center of the guide pipe (110).

[0076] Meanwhile, the inner wall of the first electrode (120) is formed with a separable structure, and the inner wall of the second electrode (130) can also be formed with a separable structure. To this end, a first separation line (DL1) and a second separation line (DL2) are formed on the inner wall of the first electrode (120), and the inner wall of the first electrode (120) can be easily replaced through the first separation line (DL1) and the second separation line (DL2).

[0077] In addition, a third separation line (DL3) and a fourth separation line (DL4) are formed on the inner wall of the second electrode (130), and the inner wall of the second electrode (130) can be easily replaced through the third separation line (DL3) and the fourth separation line (DL4).

[0078] When a swirler (150) including a guide vane (153) is installed inside a guide tube (110) in this way, the flow of the processing gas can be rotated to easily rotate the first arc point (AP1) and the second arc point (AP2).

[0079] Below, a plasma scrubber according to a third embodiment of the present invention is described.

[0080] Fig. 10 is a cross-sectional view illustrating a plasma scrubber according to a third embodiment of the present invention.

[0081] Referring to FIG. 10, the plasma scrubber (103) according to the third embodiment has the same structure as the plasma scrubber according to the first embodiment described above, except for the first additional step portion (122) and the second additional step portion (132), so a duplicate description of the same configuration is omitted.

[0082] A first additional step (122) may be formed on the upstream side of the upstream step (121), and a second additional step (132) may be formed on the downstream side of the downstream step (131).

[0083] The first additional step (122) is located upstream of the upstream step (121) and connects a portion having a larger cross-sectional area than the upstream step (121). The first additional step (122) may be formed so that the cross-sectional area gradually decreases toward the downstream. The first additional step (122) may include an inclined surface inclined with respect to the longitudinal direction of the first electrode (120).

[0084] The second additional step portion (132) is located downstream of the downstream step portion (131) and connects a portion having a larger cross-sectional area than the downstream step portion (131). The second additional step portion (132) may be formed so that the cross-sectional area gradually increases toward the downstream. The second additional step portion (132) may include an inclined surface inclined with respect to the longitudinal direction of the second electrode (130).

[0085] When the first additional step (122) is formed, the first arc point (AP1) can move from the upstream step (121) to the first additional step (122) or from the first additional step (122) to the upstream step (121) depending on the change in the flow rate of the processing gas. In addition, the second arc point (AP2) can move between the second additional step (132) and the downstream step (131) depending on the change in the flow rate of the processing gas.

[0086] Below, a plasma scrubber according to a fourth embodiment of the present invention is described.

[0087] Fig. 11 is a cross-sectional view illustrating a plasma scrubber according to a fourth embodiment of the present invention.

[0088] Referring to FIG. 11, the plasma scrubber (104) according to the fourth embodiment has the same structure as the plasma scrubber according to the first embodiment described above except for the protruding supply pipe (113), so a duplicate description of the same configuration is omitted.

[0089] A protruding supply pipe (113) for supplying processing gas to the first discharge space (DS1) is inserted into the first electrode (120). The protruding supply pipe (113) is inserted into the first electrode (120) and injects the processing gas into the interior of the first electrode (120). The protruding supply pipe (113) may be formed to have an internal cross-sectional area smaller than the cross-sectional area of ​​the throttle section (TH1).

[0090] The protruding supply pipe (113) may protrude from the lower portion of the guide pipe (110) into the interior of the first electrode (120). The outer end of the protruding supply pipe (113) may be positioned closer to the center of the first electrode (120) than the outer end of the upstream step portion (121). In addition, the shield gas injection portion (124) is formed on the outer side of the protruding supply pipe (113), and the shield gas may move downstream along the space formed on the outer side of the protruding supply pipe (113). Accordingly, a flow parallel to the axial direction of the first electrode (120) may be formed on the interior of the protruding supply pipe (113), and a swirl flow may be formed on the outer side of the protruding supply pipe (113).

[0091] When a protruding supply pipe (113) is formed as in this embodiment, the processing gas supplied from the protruding supply pipe (113) can be prevented from interfering with the rotation of the first arc point (AP1), and the first arc point (AP1) can be prevented from moving downstream due to the processing gas.

[0092] Below, a plasma scrubber according to a fifth embodiment of the present invention is described.

[0093] FIG. 12 is a cross-sectional view illustrating a plasma scrubber according to a fifth embodiment of the present invention, and FIG. 13 is a drawing illustrating a circulation area according to the fifth embodiment of the present invention.

[0094] Referring to FIGS. 12 and 13, the plasma scrubber (105) according to the fifth embodiment has the same structure as the plasma scrubber according to the first embodiment described above except for the blocking jaw (127), so a duplicate description of the same configuration is omitted.

[0095] The first electrode (120) is formed with an upstream step (121) whose inner diameter gradually decreases as it goes downstream. In addition, a blocking step (127) may be formed on the upstream side of the upstream step (121). The blocking step (127) is spaced apart from the upstream step (121) in the longitudinal direction of the first electrode (120) and protrudes inward toward the center of the first electrode (120). A groove-shaped circulation area (SA1) may be formed in the first electrode (120) by the upstream step (121) and the blocking step (127). In the circulation area (SA1), a flow moving from downstream to upstream may be formed in a portion adjacent to the wall surface of the first electrode (120).

[0096] When a blocking step (127) is formed on the upstream side of the upstream step (121) as in this embodiment, the first arc point (AP1) located upstream can maintain a stable position in the longitudinal direction without moving downstream.

[0097] Above, one embodiment of the present invention has been described, but a person having ordinary skill in the art will be able to modify and change the present invention in various ways by adding, changing, deleting or adding components, etc., within the scope that does not depart from the spirit of the present invention described in the claims, and this will also be considered to be included within the scope of the rights of the present invention.

[0098] (Explanation of symbols)

[0099] 101, 102, 103, 104, 105: Plasma scrubber

[0100] 110: Guide tube 112: Reaction accelerator supply section

[0101] 113: Protruding supply pipe 115: Insulating member

[0102] 120: First electrode 121: Upstream step

[0103] 122: First additional step 123: Shield gas passage

[0104] 124: Shield gas injection unit 125: First cooling unit

[0105] 127: Blocking jaw 128: Shield gas supply pipe

[0106] 129: Aperture 130: Second electrode

[0107] 131: Downstream step 132: Second additional step

[0108] 134: Exit 135: Second cooling section

[0109] 140: Discharge gas supply unit 143: Discharge gas distribution passage

[0110] 144: Discharge gas injection hole 148: Discharge gas supply pipe

[0111] 150: Swirl 151: Outer support tube

[0112] 152: Inner column 153: Guide vane

[0113] AC1: Arc AP1: First Arc Point

[0114] AP2: Second arc point DS1: First discharge space

[0115] DS2: Second discharge space SA1: Circulation area

[0116] TH1: Throttle range

Claims

1. A first electrode having a first discharge space extending in one direction therein; and A second electrode is disposed longitudinally from the first electrode, and has a second discharge space connected to the first discharge space and extending longitudinally therein; A plasma scrubber for large-capacity gas processing, wherein an opening is provided at a longitudinal end of the first electrode through which a processing gas is introduced.

2. In paragraph 1, A plasma scrubber for large-capacity gas processing, wherein the first discharge space includes a throttle section having a smaller cross-sectional area than the surrounding area, and the throttle section extends from the first discharge space to the second discharge space.

3. In paragraph 2, A plasma scrubber for large-capacity gas processing, wherein the first discharge space has a variable inner diameter and includes an upstream step connected to the throttle section.

4. In paragraph 3, A plasma scrubber for large-capacity gas processing, wherein the inner diameter of the upper step portion gradually decreases toward the downstream portion.

5. In paragraph 3, A plasma scrubber for large-capacity gas processing, wherein the first electrode includes a shield gas injection unit that injects shield gas into the first discharge space, and the shield gas injection unit is located upstream of the upstream step unit.

6. In paragraph 3, A plasma scrubber for large-capacity gas processing, wherein a circulation area that induces circulation flow is formed inside the first electrode, and the circulation area is located upstream of the upstream step portion.

7. In paragraph 3, A plasma scrubber for large-capacity gas processing, wherein a blocking protrusion protruding inward toward the center of the first electrode is formed on the upper portion of the above-mentioned upstream step.

8. In paragraph 3, A plasma scrubber for large-capacity gas processing, wherein the second electrode has a downstream step portion having a variable inner diameter and connected to the throttle section.

9. In paragraph 8, A plasma scrubber for large-capacity gas processing, wherein the second electrode includes a shield gas injection unit that injects shield gas into the second discharge space, and the shield gas injection unit is located downstream of the downstream step unit.

10. In paragraph 8, A plasma scrubber for large-capacity gas processing, wherein the inner diameter of the downstream step gradually increases toward the outlet.

11. In paragraph 8, A plasma scrubber for large-capacity gas processing, wherein a first additional step portion is formed on the upstream side of the above-mentioned upstream step portion, the first additional step portion connecting the above-mentioned upstream step portion with a portion having a larger cross-sectional area than the above-mentioned upstream step portion.

12. In paragraph 11, A plasma scrubber for large-capacity gas processing, wherein a second additional step portion is formed on the downstream side of the above-mentioned downstream step portion, the second additional step portion connecting the downstream step portion with a portion having a larger cross-sectional area than the above-mentioned downstream step portion.

13. In paragraph 2, A large-capacity gas processing plasma scrubber further comprising a discharge gas supply unit through which discharge gas is supplied between the first electrode and the second electrode.

14. In paragraph 2, A plasma scrubber for large-capacity gas processing, wherein a protruding supply pipe protruding inwardly of the first electrode and spraying a processing gas is installed on the first electrode, and the protruding supply pipe extends in the longitudinal direction of the first electrode.

15. In paragraph 14, A plasma scrubber for large-capacity gas processing, wherein the first electrode includes a shield gas injection unit that injects shield gas into the first discharge space, and the shield gas injection unit is located on the outside of the protruding supply pipe.

16. In paragraph 2, A plasma scrubber for large-capacity gas processing, wherein a guide pipe for delivering processing gas to the first electrode is connected to the upstream side of the first electrode, and a swirler for forming a rotating flow is installed in the guide pipe.

17. In the second paragraph, A large-capacity gas processing plasma scrubber further comprising a reaction promoting material supply unit that supplies a reaction promoting material that induces oxidation or reduction to the first discharge space or the second discharge space.

18. In paragraph 2, A plasma scrubber for large-capacity gas processing, wherein the inner wall of the first electrode and the inner wall of the second electrode are formed of a replaceable structure.

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