An apparatus for catalytic degradation of waste gas by plasma

Abstract

The device for plasma catalytic degradation of waste gas according to the present invention comprises an inner tube, an outer tube, an inner electrode, an outer electrode, and a high-voltage power supply, and further comprises a sleeve, an upper plug, a lower plug, a screw cap, an upper end cap, a lower end cap, a tightening bolt, a flow dividing plate, and a sieve plate. An exhaust gas degradation channel is formed between the inner tube and the outer tube, and circulating water is filled between the outer tube and the sleeve. An upper plug is arranged at the upper end of the inner tube, and the screw cap is in threaded connection with the upper plug. A lower plug is arranged at the lower end of the inner tube. A tightening nut is respectively arranged above and below the sleeve. The upper end cap is in threaded connection with the upper tightening nut, and the lower end cap is in threaded connection with the lower tightening nut. The inner electrode and the catalyst of the device according to the present invention are convenient to replace, have good airtightness, and stable discharge.

Description

Technical Field

[0001] The present invention relates to the technical field of waste gas treatment, and particularly relates to a device for catalytic degradation of waste gas by plasma. Background Art

[0002] Plasma contains a large number of ions, atoms, electrons, photons, excited state molecules and free radicals, and is the fourth state of matter in addition to gaseous, liquid and solid states. Among them, when the electron temperature in the plasma (generally above 10000 K) is much higher than the ion temperature (300 - 500 K), it is called thermodynamically non-equilibrium plasma (NTP), also known as low-temperature plasma. The low-temperature plasma technology is widely used in the field of waste gas treatment. The generation methods of low-temperature plasma include corona discharge, microwave discharge, glow discharge, dielectric barrier discharge (DBD), etc.

[0003] For the dielectric barrier discharge (DBD) low-temperature plasma, most of its catalytic degradation waste gas devices include components such as a high-voltage power supply, a high-voltage electrode, a low-voltage electrode, and an insulating double medium. It is found in application that the electrodes of most reaction devices are not easy to replace. When the electrodes need to be replaced, it is time-consuming and laborious, and it is very easy to damage media such as glass or quartz that fill the electrodes; after the device for catalytic degradation of waste gas by plasma discharges for a period of time, aging and sintering and other phenomena appear on the surface of the catalyst, and the loading and replacement of the catalyst are also difficult, which to a certain extent affects the progress of the plasma catalytic degradation experiment; during the process of catalytic degradation of waste gas by plasma, the surface temperature of the catalyst is high, which is easy to sinter and affect the service life of the catalyst, and the temperature of the gas to be degraded also increases; since most of the double media use fragile glass or quartz as the medium, it is easy to leak air when the medium is connected to the intake end and the outlet end, resulting in poor airtightness of the device.

[0004] Regarding the connection structure between the medium and the intake end and the outlet end, Chinese patent document CN 212548943 U (application number 202021721168.9) discloses a double dielectric barrier low-temperature plasma synergistic catalytic treatment VOCs wire tube reaction unit, which consists of an insulating medium kit, an inner electrode, an outer electrode, an end cap kit, and a packed particle catalyst. The insulating medium kit includes an inner tube, an outer tube, a perforated sealing plate, and a threaded seat. The inner electrode is installed inside the inner tube of the insulating medium kit, and one end of the inner electrode is threaded with the threaded seat; the outer electrode is closely attached to the outer wall of the outer tube of the insulating medium kit; one end of the outer tube of the insulating medium kit is connected to the end cap kit by thread, and the other end is fixedly connected to the perforated sealing plate; the packed particle catalyst is evenly placed between the inner tube and the outer tube of the insulating medium kit and is fixed in the reaction unit by the perforated sealing plate and the end cap kit, forming a one-piece synergistic structure. Summary of the Invention

[0005] The technical problem to be solved by the present invention is the problem that the inner electrode and the catalyst of the existing device for plasma catalytic degradation of waste gas are inconvenient to replace, and a device for plasma catalytic degradation of waste gas with convenient replacement of the inner electrode and the catalyst, good airtightness and stable discharge is provided.

[0006] The technical solution for achieving the object of the present invention is a device for plasma catalytic degradation of waste gas, including an inner tube, an outer tube, an inner electrode, an outer electrode, and a high-voltage power supply, and is characterized in that: it further includes a sleeve, an upper plug, a lower plug, a screw cap, an upper end cover, a lower end cover, a tightening bolt, a flow dividing plate, and a sieve plate.

[0007] The inner tube, the outer tube, and the sleeve are coaxially arranged in the order from the inside to the outside. The waste gas degradation channel is between the inner tube and the outer tube, and circulating water is filled between the outer tube and the sleeve.

[0008] An upper plug is arranged at the upper end of the inner tube. The screw cap is threadedly connected to the upper plug, and a lower plug is arranged at the lower end of the inner tube.

[0009] A tightening nut is respectively arranged above and below the sleeve. The upper end cover is threadedly connected to the upper tightening nut, and the lower end cover is threadedly connected to the lower tightening nut.

[0010] The flow dividing plate is sleeved on the outer periphery of the inner tube and is arranged below the pipe orifice of the outer tube; the sieve plate is sleeved on the outer periphery of the inner tube.

[0011] A water inlet, a water outlet, and a wire channel are arranged on the sleeve. The water inlet is arranged at the lower part of the sleeve, and the water outlet and the wire channel are arranged at the upper part of the sleeve.

[0012] The inner electrode is a solid metal rod or metal powder, and is placed or filled in the space formed by the inner tube, the upper plug, and the lower plug.

[0013] The outer electrode is a metal strip or metal sheet, and is fixed on the outer side wall of the outer tube; or the outer electrode is the circulating water between the outer tube and the sleeve.

[0014] A channel is arranged in the center of the upper plug. The upper plug includes a plug-in part and a connecting part. The plug-in part is tightly plugged and connected to the upper pipe orifice of the inner tube, and the connecting part is provided with an external thread and is threadedly connected to the screw cap.

[0015] The screw cap is composed of two coaxial cylinders with a smaller upper part and a larger lower part. The upper cylinder is used for positioning with the upper end cover, and a screw hole is arranged in the center of the lower cylinder. The screw cap is threadedly connected to the upper plug through this screw hole.

[0016] The lower plug is composed of two cylinders with different diameters, namely a sealing part tightly plugged with the lower pipe orifice of the inner tube and a fixing part. A screw hole is opened in the fixing part.

[0017] The tightening nut includes two hole segments with different inner diameters. The hole segment with a smaller inner diameter is in clearance fit with the outer tube. The screw hole segment with a larger inner diameter is used for threaded connection with the upper end cover or the lower end cover. An annular platform is included inside the tightening nut, and the sealing ring is placed on this platform.

[0018] The upper end cover includes a main body and a nut connection part. The nut connection part is provided with an external thread. The upper end cover is threadedly connected to the upper tightening nut through the nut connection part. After the upper end cover and the tightening nut are tightened, the sealing ring is pressed against the outer tube.

[0019] The main body is provided with an inner cavity with an opening facing downwards, a positioning hole and an air outlet. The air outlet is communicated with the inner cavity of the main body.

[0020] A channel is opened in the center of the nut connection part. The inner cavity of the main body and the channel of the nut connection part are coaxial, and the inner diameter of the channel of the nut connection part is larger than the inner diameter of the inner cavity of the main body. An annular mounting table is formed between the main body and the nut connection part, and the upper end pipe orifice of the outer tube is pressed against the annular mounting table.

[0021] The lower end cover includes a main body part and a lower nut connection part. The lower nut connection part is provided with an external thread. After the lower nut connection part is tightened with the lower tightening nut, the sealing ring is pressed against the outer tube.

[0022] The main body part is provided with an inner cavity with an opening facing upwards, a through hole and an air inlet. The inner cavity is communicated with the air inlet.

[0023] A channel is opened in the center of the lower nut connection part. The inner cavity of the main body part and the channel of the lower nut connection part are coaxial, and the inner diameter of the channel of the lower nut connection part is larger than the inner diameter of the inner cavity of the main body part. An annular platform is formed between the main body part and the lower nut connection part.

[0024] The fixing part of the lower plug is located in the through hole of the lower end cover. The screw hole of the lower plug faces downwards, and the bolt is screwed into the screw hole of the lower plug from below.

[0025] The flow dividing plate is sleeved outside the inner tube and placed on the annular platform of the lower end cover. The lower end pipe orifice of the outer tube is pressed against the flow dividing plate.

[0026] An annular groove with an opening facing upwards is opened on the sieve plate. A circle of holes is also provided on the sieve plate. The holes are located in the annular groove, and the groove is filled with a catalyst.

[0027] Further, adjacent two layers of sieve plates are supported by upper support rods. The lowermost sieve plate and the flow dividing plate are supported by lower support rods.

[0028] The present invention has positive effects:

[0029] (1) The device for plasma catalytic degradation of waste gas in the present invention is convenient for replacing the inner electrode. Unscrew the upper end cover, and then unscrew the screw cap from the upper plug, and the inner electrode can be taken out or metal powder can be added into the inner tube. Since the screw cap and the upper plug, as well as the upper end cover and the tightening nut, are all connected by threads, the disassembly and assembly operations are relatively convenient.

[0030] (2) The device for plasma catalytic degradation of waste gas in the present invention is also convenient for replacing the catalyst. After removing the upper end cover, the sieve plate can be taken out to replace the catalyst.

[0031] (3) The upper plug and the screw cap are arranged at the upper end of the inner tube of the present invention. The upper end part of the inner tube, the upper plug and the screw cap are located inside the upper end cover. The lower plug is arranged at the lower end of the inner tube, and the lower end part of the inner tube and the lower plug are located inside the lower end cover. After the upper end cover and the lower end cover are respectively tightened with the upper and lower tightening nuts, the sealing ring is pressed against the outer tube, making it closely fit on the outer tube; the upper and lower pipe orifices of the outer tube are both closely fitted with the corresponding planes; in addition, the air inlet and the air outlet are both threaded holes, which are threadedly and tightly matched with the air inlet pipe and the air outlet pipe, fully ensuring the airtightness of the device.

[0032] (4) A water jacket is also arranged outside the outer tube of the present invention. The circulating water fills the cavity between the outer tube and the water jacket. On the one hand, the circulating water is used to cool the waste gas and the catalyst to be degraded between the inner and outer tubes. The waste gas and the catalyst are continuously cooled, so that the discharge is more stable. On the other hand, it can also be used as an outer electrode. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of the device for plasma catalytic degradation of waste gas in the present invention.

[0034] Figure 2 It is a schematic connection diagram of the inner tube and the plug.

[0035] Figure 3 It is a schematic structural diagram of the upper end cover.

[0036] Figure 4 It is a schematic structural diagram of the lower end cover.

[0037] Figure 5 It is a schematic connection diagram of the inner tube and the upper and lower end covers.

[0038] Figure 6 It is a schematic structural diagram of the tightening nut.

[0039] Figure 7 It is a front view of the flow dividing plate.

[0040] Figure 8 It is a top view of the flow dividing plate.

[0041] Figure 9 It is a front view of the sieve plate.

[0042] Figure 10 It is a top view of the sieve plate.

[0043] The markings in the above-mentioned drawings are as follows:

[0044] Inner tube 1, outer tube 2, sleeve 3, inner electrode 4, upper plug 5, insertion part 5-1, connection part 5-2, lower plug 6, sealing part 6-1, fixing part 6-2, screw hole 6-2-1, screw cap 7, upper end cover 8, main body 8-1, nut connection part 8-2, positioning hole 8-3, mounting table 8-4, lower end cover 9, main body part 9-1, lower nut connection part 9-2, through hole 9-3, annular platform 9-4, tightening nut 10, sealing ring 11, flow dividing plate 12, air flow hole 12-1, sieve plate 13, groove 13-1, hole 13-2, upper support rod 14, lower support rod 15, bolt 16, air inlet 17, air outlet 18, water inlet 19, water outlet 20, wire channel 21. Detailed implementation mode

[0045] (Embodiment 1)

[0046] See Figures 1 to 5 , the device for catalytic degradation of waste gas by plasma in this embodiment includes an inner tube 1, an outer tube 2, a sleeve 3, an inner electrode (high-voltage electrode) 4, an outer electrode (low-voltage electrode), an upper plug 5, a lower plug 6, a screw cap 7, an upper end cover 8, a lower end cover 9, a tightening nut 10, a sealing ring 11, a flow dividing plate 12, a sieve plate 13 and a high-voltage power supply; the inner tube 1, the outer tube 2, and the sleeve 3 are coaxially arranged in order from the inside to the outside, the waste gas degradation channel is between the inner tube 1 and the outer tube 2, and circulating water is filled between the outer tube 2 and the sleeve 3; an upper plug 5 is arranged at the upper end of the inner tube 1, the screw cap 7 is threadedly connected to the upper plug 5, and a lower plug 6 is arranged at the lower end of the inner tube 1; a tightening nut 10 is arranged respectively above and below the sleeve 3, the upper end cover 8 is threadedly connected to the upper tightening nut 10, and the lower end cover 9 is threadedly connected to the lower tightening nut 10; the flow dividing plate 12 is sleeved on the outer periphery of the inner tube 1 and is arranged below the pipe orifice of the outer tube 2; the sieve plate 13 is sleeved on the outer periphery of the inner tube 1 and is located at a position close to the lower pipe orifice of the outer tube 2, within the interval height where the sleeve 3 is located.

[0047] The high-voltage power supply is a pulse-modulated resonant power supply, the power is a sine wave, and the modulation waveform is a rectangular wave.

[0048] The inner tube 1 is a quartz tube or a ceramic tube, the outer tube 2 is a quartz tube or a ceramic tube, and the inner tube 1 and the outer tube 2 form an insulating double dielectric.

[0049] The sleeve 3 is provided with a water inlet 19, a water outlet 20 and a wire channel 21, the water inlet 19 is arranged at the lower part of the sleeve 3, and the water outlet 20 and the wire channel 21 are arranged at the upper part of the sleeve 3.

[0050] The inner electrode 4 is a solid metal rod or metal powder with a low melting point (such as iron powder, aluminum powder, stainless steel powder or magnesium powder), and is placed or filled in the space formed by the inner tube 1, the upper plug 5 and the lower plug 6.

[0051] The outer electrode is a metal strip or metal sheet (such as copper foil, aluminum foil, etc.), and is fixed on the outer wall of the outer tube 2. The inner electrode, the high-voltage power supply and the outer electrode are connected by wires; the wire connecting the inner electrode is led out from the upper end cover 8 and connected to the high-voltage power supply, and the wire connecting the outer electrode extends out from the wire channel 21 of the sleeve 3 and is connected to the high-voltage power supply.

[0052] See Figure 2 , a channel is provided in the center of the upper plug 5. The upper plug 5 includes a plug-in part 5-1 and a connecting part 5-2. The plug-in part 5-1 is tightly plugged and connected to the upper pipe orifice of the inner tube 1, and the connecting part 5-2 is provided with an external thread and is threadedly connected to the screw cap 7.

[0053] The lower plug 6 is composed of two cylinders with different diameters, namely a sealing part 6-1 that is tightly plugged into the lower pipe orifice of the inner tube 1 and a fixing part 6-2 used for connecting to the lower end cover 9. A screw hole 6-2-1 is opened in the fixing part 6-2.

[0054] The screw cap 7 is composed of two coaxial cylinders with a smaller upper part and a larger lower part. The upper cylinder is used for positioning with the upper end cover 8, and a screw hole is provided in the center of the lower cylinder. The screw cap 7 is threadedly connected to the upper plug 5 through this screw hole.

[0055] For the inner tube 1, the outer tube 2 and the sleeve 3 that are coaxially arranged in the order from the inside to the outside, the upper and lower heights decrease in turn.

[0056] There are two tightening nuts 10, which are respectively arranged above and below the sleeve 3 and are sleeved on the outer periphery of the outer tube 2.

[0057] See Figure 6 , the tightening nut 10 includes two hole sections with different inner diameters. The hole section with a smaller inner diameter has an interference fit with the outer tube 2; the hole section with a larger inner diameter is a threaded hole section for threadedly connecting with the upper end cover 8 or the lower end cover 9. The hole sections with different inner diameters form an annular platform, and a sealing ring 11 is placed on this platform.

[0058] See Figure 3 , the upper end cover 8 includes a main body 8-1 and a nut connecting part 8-2, and the nut connecting part 8-2 is provided with an external thread. The main body 8-1 is provided with an inner cavity with an opening facing downwards, a positioning hole 8-3 and an air outlet 18; a channel is opened in the center of the nut connecting part 8-2; the inner cavity of the main body 8-1 is coaxial with the channel of the nut connecting part 8-2, and the inner diameter of the channel of the nut connecting part 8-2 is larger than the inner diameter of the inner cavity of the main body 8-1. Therefore, an annular mounting table 8-4 is formed between the main body 8-1 and the nut connecting part 8-2, and the upper pipe orifice of the outer tube 2 is pressed against the annular mounting table 8-4.

[0059] The upper cylinder of the rotary cap 7 is located within the positioning hole 8-3 of the upper end cap 8.

[0060] The air outlet 18 communicates with the inner cavity of the main body 8-1 of the upper end cap 8. The upper section of the inner tube 1 is located inside the inner cavity of the main body 8-1, and the degraded waste gas flows out of the device from the air outlet 18.

[0061] The upper end cap 8 is threadedly connected to the tightening nut 10 through the nut connection part 8-2. After the upper end cap 8 and the tightening nut 10 are tightened, the sealing ring 11 is pressed against the outer tube 2.

[0062] See Figure 4 , the lower end cap 9 includes a main body part 9-1 and a lower nut connection part 9-2. The lower nut connection part 9-2 is provided with an external thread. After the lower nut connection part 9-2 is tightened with the lower tightening nut 10 below, the sealing ring 11 is pressed against the outer tube 2.

[0063] The main body part 9-1 is provided with an inner cavity with an upward opening, a through hole 9-3 and an air inlet 17; a channel is provided in the center of the lower nut connection part 9-2; the inner cavity of the main body part 9-1 and the channel of the lower nut connection part 9-2 are coaxial, and the inner diameter of the channel of the lower nut connection part 9-2 is larger than the inner diameter of the inner cavity of the main body part 9-1. Therefore, an annular platform 9-4 is formed between the main body part 9-1 and the lower nut connection part 9-2.

[0064] The fixing part 6-2 of the lower plug 6 is located within the through hole 9-3 of the lower end cap 9. The screw hole 6-2-1 of the lower plug 6 faces downward, and the bolt 16 is screwed into the screw hole 6-2-1 of the lower plug 6 from below to fix the lower plug 6 to the lower end cap 9.

[0065] The air inlet 17 communicates with the inner cavity of the main body part 9-1 of the lower end cap 9. Both the air inlet 17 and the air outlet 18 are threaded holes, which are tightly threadedly fitted with the inlet pipe and the outlet pipe to ensure the airtightness of the device.

[0066] The lower end pipe orifice of the inner tube 1 is pressed against the main body part 9-1 of the lower end cap 9.

[0067] The waste gas to be degraded enters the inner cavity of the main body part 9-1 of the lower end cap 9 from the air inlet 17, and then enters the annular channel between the inner tube 1 and the outer tube 2 after passing through the flow dividing plate 12.

[0068] The flow dividing plate 12 is sleeved outside the inner tube 1 and placed on the annular platform 9-4 of the lower end cap 9. The lower end pipe orifice of the outer tube 2 is pressed against the flow dividing plate 12.

[0069] See Figure 7 and Figure 8 , the flow dividing plate 12 includes a through hole in the center for sleeving and a circle of air flow holes 12-1 outside the through hole.

[0070] See Figure 9 and Figure 10, the sieve plate 13 is sleeved outside the inner tube 1. An annular groove 13-1 with an upward opening is formed on the sieve plate 13, and a circle of through holes 13-2 are also provided on the sieve plate 13. The holes 13-2 are located in the annular groove 13-1. The catalyst is filled in the groove 13-1.

[0071] In this embodiment, two layers of sieve plates 13 are arranged within the height range of the plasma interval where the sleeve 3 is located. The two layers of sieve plates 13 are supported by the upper support rods 14. The lowermost sieve plate 13 and the flow dividing plate 12 are supported by the lower support rods 15.

[0072] If more than two layers of sieve plates 13 are arranged in the degradation interval, upper support rods 14 are respectively arranged between adjacent two layers of sieve plates 13 for support.

[0073] During operation, circulating cooling water is introduced into the sleeve 3. After the circuit is connected, the waste gas to be degraded enters the inner cavity of the main body 9-1 of the lower end cover 9 from the air inlet 17, and after being divided by the flow dividing plate 12, it enters the space between the inner tube 1 and the outer tube 2; after passing through the sieve plate 13 and being catalytically degraded, it enters the inner cavity of the main body 8-1 of the upper end cover 8 and flows out from the air outlet 18.

[0074] The circulating cooling water between the sleeve 3 and the outer tube 2 cools the gas and the catalyst between the inner tube 1 and the outer tube 2, making the temperature in the area where the catalyst is placed more uniform, and the effect of uniform discharge can be achieved under high-power drive; at the same time, due to the cooling effect, the influence of the catalyst on the plasma discharge characteristics is improved, and further the waste gas degradation effect is improved.

[0075] (Embodiment 2)

[0076] The rest of the device for catalytic degradation of waste gas by plasma in this embodiment is the same as that in the embodiment, except that: the outer electrode is the circulating water filled between the outer tube 2 and the sleeve 3, and after the wire is connected to the high-voltage power supply, it extends into the circulating water from the wire channel 21.

[0077] Taking water as the electrode and introducing the wire into the water, after the circuit is connected, the waste gas to be degraded enters the inner cavity of the main body 9-1 of the lower end cover 9 from the air inlet 17, and after being divided by the flow dividing plate 12, it enters the space between the inner tube 1 and the outer tube 2; after passing through the sieve plate 13 and being catalytically degraded, it enters the inner cavity of the main body 8-1 of the upper end cover 8 and flows out from the air outlet 18.

[0078] The circulating cooling water between the sleeve 3 and the outer tube 2 serves as the outer electrode on the one hand and cools the gas and the catalyst between the inner tube 1 and the outer tube 2 on the other hand, making the temperature in the area where the catalyst is placed more uniform, and the effect of uniform discharge can be achieved under high-power drive; at the same time, due to the cooling effect, the influence of the catalyst on the plasma discharge characteristics is improved, and further the waste gas degradation effect is improved.

Claims

1. An apparatus for catalytic degradation of waste gas by plasma, comprising an inner tube (1), an outer tube (2), an inner electrode (4), an outer electrode, and a high-voltage power supply, characterized in that: It further includes a casing (3), an upper plug (5), a lower plug (6), a rotary cap (7), an upper end cover (8), a lower end cover (9), a tightening nut (10), a flow dividing plate (12) and a sieve plate (13); The inner tube (1), the outer tube (2) and the casing (3) are coaxially arranged in the order from the inside to the outside. An exhaust gas degradation channel is formed between the inner tube (1) and the outer tube (2), and circulating water is filled between the outer tube (2) and the casing (3); An upper plug (5) is arranged at the upper end of the inner tube (1), the rotary cap (7) is threadedly connected to the upper plug (5), and a lower plug (6) is arranged at the lower end of the inner tube (1); A channel is arranged in the center of the upper plug (5). The upper plug (5) includes a plugging portion (5-1) and a connecting portion (5-2). The plugging portion (5-1) is tightly plugged and connected to the upper pipe orifice of the inner tube (1), and the connecting portion (5-2) is provided with an external thread and is threadedly connected to the rotary cap (7); The rotary cap (7) is composed of two coaxial cylinders with a smaller upper part and a larger lower part. The upper cylinder is positioned with the upper end cover (8), and a screw hole is arranged in the center of the lower cylinder. The rotary cap (7) is threadedly connected to the upper plug (5) through this screw hole; The lower plug (6) is composed of two cylinders with different diameters, namely a sealing portion (6-1) and a fixing portion (6-2). The sealing portion (6-1) is tightly plugged and connected to the lower pipe orifice of the inner tube (1), and a screw hole (6-2-1) is opened in the fixing portion (6-2); One tightening nut (10) is respectively arranged above and below the casing (3). The tightening nut (10) includes two hole sections with different inner diameters. The hole section with a smaller inner diameter is in clearance fit with the outer tube (2); the screw hole section with a larger inner diameter is used for threaded connection with the upper end cover (8) or the lower end cover (9); an annular platform is included inside the tightening nut (10), and the sealing ring (11) is placed on this platform; the upper end cover (8) is threadedly connected to the upper tightening nut (10), and the lower end cover (9) is threadedly connected to the lower tightening nut (10); The upper end cover (8) includes a main body (8-1) and a nut connecting portion (8-2). The nut connecting portion (8-2) is provided with an external thread. The upper end cover (8) is threadedly connected to the upper tightening nut (10) through the nut connecting portion (8-2); an inner cavity with an opening facing downwards, a positioning hole (8-3) and an air outlet (18) are opened in the main body (8-1). The air outlet (18) is communicated with the inner cavity of the main body (8-1), and the upper cylinder of the rotary cap (7) is located in the positioning hole (8-3) of the upper end cover (8); A channel is opened in the center of the nut connecting portion (8-2). The inner cavity of the main body (8-1) is coaxial with the channel of the nut connecting portion (8-2), and the inner diameter of the channel of the nut connecting portion (8-2) is larger than the inner diameter of the inner cavity of the main body (8-1). An annular mounting table (8-4) is formed between the main body (8-1) and the nut connecting portion (8-2), and the upper pipe orifice of the outer tube (2) is pressed against the annular mounting table (8-4); The lower end cover (9) includes a main body portion (9-1) and a lower nut connecting portion (9-2). The lower nut connecting portion (9-2) is provided with an external thread. After the lower nut connecting portion (9-2) is tightened with the lower tightening nut (10), the sealing ring (11) is pressed against the outer tube (2); The main body part (9-1) is provided with an inner cavity with an upward opening, a through hole (9-3) and an air inlet (17), and the inner cavity is communicated with the air inlet (17). The fixing part (6-2) of the lower plug (6) is located in the through hole (9-3) of the lower end cover (9). The threaded hole (6-2-1) of the lower plug (6) faces downward, and the bolt (16) is screwed into the threaded hole (6-2-1) of the lower plug (6) from below. The flow dividing plate (12) is sleeved on the outer periphery of the inner tube (1) and is arranged below the pipe orifice of the outer tube (2); the sieve plate (13) is sleeved on the outer periphery of the inner tube (1).

2. The device for plasma catalytic degradation of waste gas according to claim 1, wherein: The water inlet (19), the water outlet (20) and the wire channel (21) are arranged on the sleeve (3). The water inlet (19) is arranged at the lower part of the sleeve (3), and the water outlet (20) and the wire channel (21) are arranged at the upper part of the sleeve (3).

3. The apparatus for plasma catalytic degradation of waste gas according to claim 1, characterized in that: The inner electrode (4) is a solid metal rod or metal powder and is placed or filled in the space formed by the inner tube (1), the upper plug (5) and the lower plug (6).

4. The apparatus for catalytic degradation of waste gas by plasma according to claim 3, wherein: The outer electrode is a metal strip or metal sheet and is fixed on the outer side wall of the outer tube (2); or the outer electrode is the circulating water between the outer tube (2) and the sleeve (3).

5. The device for catalytic degradation of waste gas by plasma according to claim 1, characterized in that: After the upper end cover (8) and the tightening nut (10) are tightened, the sealing ring (11) is pressed against the outer tube (2).

6. The device for plasma catalytic degradation of waste gas according to claim 1, wherein: A channel is opened at the center of the lower nut connecting part (9-2) of the lower end cover (9). The inner cavity of the main body part (9-1) and the channel of the lower nut connecting part (9-2) are coaxial, and the inner diameter of the channel of the lower nut connecting part (9-2) is larger than the inner diameter of the inner cavity of the main body part (9-1). An annular platform (9-4) is formed between the main body part (9-1) and the lower nut connecting part (9-2).

7. The device for plasma catalytic degradation of waste gas according to claim 6, characterized in that: The flow dividing plate (12) is sleeved outside the inner tube (1) and is placed on the annular platform (9-4) of the lower end cover (9), and the lower pipe orifice of the outer tube (2) is pressed against the flow dividing plate (12). An annular groove (13-1) with an upward opening is opened on the sieve plate (13). A circle of holes (13-2) is also arranged on the sieve plate (13). The holes (13-2) are located in the annular groove (13-1), and the catalyst is filled in the groove (13-1). Adjacent two layers of sieve plates (13) are supported by the upper support rods (14), and the lowermost sieve plate (13) and the flow dividing plate (12) are supported by the lower support rods (15).

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