A microwave-based plasma torch

Abstract

The present invention discloses a microwave-based plasma torch, which belongs to the field of microwave application technology, and comprises a shielding shell and an input pipe; the input pipe runs through the shielding shell; the input pipe comprises an inlet pipe portion located above the shielding shell, a microwave-permeable tube portion located inside the shielding shell, and an outlet pipe portion located below the shielding shell; a feed port is provided on the shielding shell; the feed port is used to input microwaves to the microwave-permeable tube portion; at least one working air inlet pipe is provided on the inlet pipe portion; the working air inlet pipe is used to input working gas; and the outlet pipe portion is used to output flame. The microwave-based plasma torch of the present invention utilizes microwaves to generate plasma to decompose waste gas, and has the characteristics of long service life, high processing efficiency, energy saving, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave application, and in particular relates to a plasma torch based on microwave. Background Art

[0002] Low-temperature plasma is the fourth state of matter after solid, liquid and gas. When the applied voltage reaches the discharge voltage of the gas, the gas is broken down to produce a mixture of electrons, various ions, atoms and free radicals. Although the temperature of electrons is very high during the discharge process, the temperature of heavy particles is very low, and the entire system is in a low-temperature state, so it is called low-temperature plasma. Low-temperature plasma degradation of pollutants is to use these high-energy electrons, free radicals and other active particles and pollutants in the exhaust gas to decompose the pollutant molecules in a very short time, and various subsequent reactions occur to achieve the purpose of degrading pollutants.

[0003] However, the method of using external voltage to achieve gas discharge to generate plasma requires frequent replacement of electrodes, high voltage is generated at both ends of the electrodes, and plasma will bombard the electrodes, causing damage to the electrodes and shortening the service life of the equipment. In addition, the electrode method is less efficient than the microwave method at the same power. Using microwaves to generate and maintain plasma to decompose waste gas is more efficient, mainly because microwaves have high frequency and high photon energy, so the electron concentration generated at the same power is high, so the waste gas treatment efficiency is higher. Summary of the invention

[0004] The purpose of the present invention is to provide a microwave-based plasma torch to address the above shortcomings, and to solve the problems of short life and low treatment efficiency of the existing electrode-type plasma equipment in treating waste gas. To achieve the above purpose, the present invention provides the following technical solutions:

[0005] A microwave-based plasma torch comprises a shielding shell and an input pipe; the input pipe penetrates the shielding shell; the input pipe comprises an inlet pipe portion located above the shielding shell, a microwave-transparent tube portion located inside the shielding shell, and an outlet pipe portion located below the shielding shell; a feed port is provided on the shielding shell; the feed port is used to input microwaves into the microwave-transparent tube portion; the inlet pipe portion is provided with at least one working air inlet pipe; the working air inlet pipe is used to input working gas; and the outlet pipe portion is used to output flame. It can be seen from the above structure that the shielding shell generally adopts a metal shell to reduce microwave leakage; the input pipe is a hollow structure, and it is not limited whether it is a regular cross-section or whether it is detachable; the input pipe includes an inlet pipe part located above the shielding shell, and the inlet pipe part is used to input working gas, or both working gas and waste gas to be treated; the working gas is generally nitrogen or argon; waste gas, such as waste gas treated by scrubber in CVD equipment in the semiconductor industry; the microwave-permeable tube part inside the shielding shell can transmit microwaves, and is generally made of quartz. The microwave frequency is high and the photon energy is high, which can make the working gas produce high-concentration electrons and decompose the waste gas. In addition, since the plasma temperature is also high, it also promotes the decomposition of the waste gas; the feed port is the microwave inlet. The inlet into the shielding shell can be directly or indirectly connected to the waveguide and the microwave source; at least one working air inlet pipe is provided on the inlet pipe part. If only working gas flows in the inlet pipe part, the working air inlet pipe can be the inlet pipe part itself, directly input from the upper end of the inlet pipe part, or the working air inlet pipe can be a branch pipe separately provided on the outer side of the inlet pipe part; if both working gas and exhaust gas flow in the inlet pipe part, the working air inlet pipe is a branch pipe separately provided on the outer side of the inlet pipe part, and the exhaust gas is directly input from the upper end of the inlet pipe part; the working gas flows from the inlet pipe part to the outlet pipe part, and the generated flame is output from the outlet pipe part; a section of microwave suppressor is provided at the connection part of the inlet pipe part and the outlet pipe part with the shielding shell, which is generally a section of metal pipe to reduce the escape of microwaves from the through hole on the shielding shell. Since microwaves are used to generate plasma at the same power, the electron concentration is high, so the efficiency of treating exhaust gas is higher. In addition, since the electrodes are abandoned, there is no need to replace the electrodes, the service life is longer, and resources are saved.

[0006] Furthermore, the inlet pipe part includes a metal inlet pipe; the metal inlet pipe is fixed on the top of the shielding shell; and at least one working air inlet pipe is provided on the side surface of the metal inlet pipe. As can be seen from the above structure, the working gas enters the metal inlet pipe from the working air inlet pipe on the side surface of the metal inlet pipe and flows to the outlet pipe part; the metal inlet pipe itself also plays the role of a microwave suppressor.

[0007] Furthermore, the outlet pipe portion includes a metal outlet pipe, and the metal outlet pipe is fixed to the bottom of the shielding shell. From the above structure, it can be seen that the metal outlet pipe also plays the role of a microwave suppressor.

[0008] Furthermore, the microwave-transmissive tube portion includes a quartz tube; the quartz tube connects the metal inlet tube and the metal outlet tube, so that the gas in the input tube cannot enter the shielding shell. From the above structure, it can be seen that the quartz tube can extend upward from the metal inlet tube, so that the working air inlet tube can be arranged on the quartz tube, and the metal inlet tube and the upper part of the quartz tube both belong to the inlet tube portion; the quartz tube can extend downward from the metal outlet tube, so that the metal outlet tube and the lower part of the quartz tube both belong to the outlet tube portion, and the flame is ejected from the lower part of the quartz tube; if the quartz tube does not extend downward from the metal outlet tube, the flame is ejected from the metal outlet tube.

[0009] Furthermore, the working gas inputted into the input pipe by the working air intake pipe moves in a spiral forward manner. As can be seen from the above structure, the center line of the working air intake pipe can be tilted downward and deviate from the center line of the input pipe, and the air is taken in along the inner wall of the input pipe, so that the working gas will begin to flow downward in a spiral along the inner wall of the input pipe, which is conducive to taking away the heat of the input pipe through the working gas, making the equipment more durable and having better heat dissipation.

[0010] Furthermore, it also includes an igniter; the igniter is used to generate a tip discharge in the input tube. As can be seen from the above structure, the igniter can be inserted from the inlet tube to generate a tip discharge, instantly stimulate plasma generation, and then be taken away from the inlet tube, which is conducive to reducing the power of the microwave source and saving costs.

[0011] Furthermore, it also includes a compression waveguide and a microwave source; the microwave source is connected to the feed port through the compression waveguide. From the above structure, it can be seen that the compression waveguide increases the energy density of microwaves entering the microwave source and improves the efficiency of generating plasma.

[0012] Furthermore, the microwave is input from the feed port, passes through the center of the microwave-transmissive tube, and then is reflected by the inner wall of the shielding shell. The distance from the inner wall of the shielding shell to the center of the microwave-transmissive tube is 0.5*n+0.25 times the wavelength, where n is a non-negative integer. It can be seen from the above structure that this size makes the electric field in the center of the microwave-transmissive tube the strongest, thereby improving the efficiency of generating plasma.

[0013] Furthermore, there are two working air intake pipes, which are evenly surrounded on the air intake part.

[0014] The beneficial effects of the present invention are:

[0015] The present invention discloses a microwave-based plasma torch, comprising a shielding shell and an input pipe; the input pipe penetrates the shielding shell; the input pipe comprises an inlet pipe portion located above the shielding shell, a microwave-permeable tube portion located inside the shielding shell, and an outlet pipe portion located below the shielding shell; a feed port is provided on the shielding shell; the feed port is used to input microwaves into the microwave-permeable tube portion; at least one working air inlet pipe is provided on the inlet pipe portion; the working air inlet pipe is used to input working gas; and the outlet pipe portion is used to output flame. The microwave-based plasma torch of the present invention utilizes microwaves to generate plasma to decompose waste gas, and has the characteristics of long service life, high processing efficiency, energy saving, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0017] Figure 2 This is a schematic diagram of the top view of the metal inlet pipe of the present invention;

[0018] In the attached drawings: 1-shielding shell, 2-working air inlet pipe, 3-metal inlet pipe, 4-metal outlet pipe, 5-quartz tube, 6-lighter, 7-compression waveguide, 8-microwave source. DETAILED DESCRIPTION

[0019] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods, but the present invention is not limited to the following embodiments.

[0020] Embodiment 1:

[0021] See attached Figures 1-2A microwave-based plasma torch comprises a shielding shell 1 and an input pipe; the input pipe penetrates the shielding shell 1; the input pipe comprises an inlet pipe portion located above the shielding shell 1, a microwave-transmissive tube portion located inside the shielding shell 1, and an outlet pipe portion located below the shielding shell 1; a feed port is provided on the shielding shell 1; the feed port is used to input microwaves into the microwave-transmissive tube portion; at least one working air inlet pipe 2 is provided on the inlet pipe portion; the working air inlet pipe 2 is used to input working gas; and the outlet pipe portion is used to output flames. It can be seen from the above structure that the shielding shell 1 generally adopts a metal shell to reduce microwave leakage; the input pipe is a hollow structure, and it is not limited whether it is a regular cross-section or whether it is detachable; the input pipe includes an inlet pipe part located above the shielding shell 1, and the inlet pipe part is used to input working gas, or both working gas and waste gas to be treated; the working gas is generally nitrogen or argon; waste gas, such as waste gas treated by scrubber in CVD equipment in the semiconductor industry; the microwave-permeable tube part inside the shielding shell 1 can transmit microwaves, and is generally made of quartz. The microwave frequency is high and the photon energy is high, which can make the working gas produce high-concentration electrons and decompose the waste gas. In addition, since the plasma temperature is also high, it also promotes the decomposition of the waste gas; the feed port is where microwaves enter the shielding shell 1. The inlet inside the shielding shell 1 can be directly or indirectly connected to the waveguide and the microwave source; at least one working air inlet pipe 2 is provided on the inlet pipe part. If only working gas flows in the inlet pipe part, the working air inlet pipe 2 can be the inlet pipe part itself, directly input from the upper end of the inlet pipe part, or the working air inlet pipe 2 can be a branch pipe separately provided on the outer side of the inlet pipe part; if both working gas and exhaust gas flow in the inlet pipe part, the working air inlet pipe 2 is a branch pipe separately provided on the outer side of the inlet pipe part, and the exhaust gas is directly input from the upper end of the inlet pipe part; the working gas flows from the inlet pipe part to the outlet pipe part, and the generated flame is output from the outlet pipe part; a section of microwave suppressor is provided at the connection part between the inlet pipe part and the outlet pipe part and the shielding shell 1, which is generally a section of metal pipe to reduce the escape of microwaves from the through hole on the shielding shell 1. Since microwaves are used to generate plasma at the same power, the electron concentration is high, so the efficiency of treating exhaust gas is higher. In addition, since the electrodes are abandoned, there is no need to replace the electrodes, the service life is longer, and resources are saved.

[0022] Embodiment 2:

[0023] See attached Figures 1-2A microwave-based plasma torch comprises a shielding shell 1 and an input pipe; the input pipe penetrates the shielding shell 1; the input pipe comprises an inlet pipe portion located above the shielding shell 1, a microwave-transmissive tube portion located inside the shielding shell 1, and an outlet pipe portion located below the shielding shell 1; a feed port is provided on the shielding shell 1; the feed port is used to input microwaves into the microwave-transmissive tube portion; at least one working air inlet pipe 2 is provided on the inlet pipe portion; the working air inlet pipe 2 is used to input working gas; and the outlet pipe portion is used to output flames. It can be seen from the above structure that the shielding shell 1 generally adopts a metal shell to reduce microwave leakage; the input pipe is a hollow structure, and it is not limited whether it is a regular cross-section or whether it is detachable; the input pipe includes an inlet pipe part located above the shielding shell 1, and the inlet pipe part is used to input working gas, or both working gas and waste gas to be treated; the working gas is generally nitrogen or argon; waste gas, such as waste gas treated by scrubber in CVD equipment in the semiconductor industry; the microwave-permeable tube part inside the shielding shell 1 can transmit microwaves, and is generally made of quartz. The microwave frequency is high and the photon energy is high, which can make the working gas produce high-concentration electrons and decompose the waste gas. In addition, since the plasma temperature is also high, it also promotes the decomposition of the waste gas; the feed port is where microwaves enter the shielding shell 1. The inlet inside the shielding shell 1 can be directly or indirectly connected to the waveguide and the microwave source; at least one working air inlet pipe 2 is provided on the inlet pipe part. If only working gas flows in the inlet pipe part, the working air inlet pipe 2 can be the inlet pipe part itself, directly input from the upper end of the inlet pipe part, or the working air inlet pipe 2 can be a branch pipe separately provided on the outer side of the inlet pipe part; if both working gas and exhaust gas flow in the inlet pipe part, the working air inlet pipe 2 is a branch pipe separately provided on the outer side of the inlet pipe part, and the exhaust gas is directly input from the upper end of the inlet pipe part; the working gas flows from the inlet pipe part to the outlet pipe part, and the generated flame is output from the outlet pipe part; a section of microwave suppressor is provided at the connection part between the inlet pipe part and the outlet pipe part and the shielding shell 1, which is generally a section of metal pipe to reduce the escape of microwaves from the through hole on the shielding shell 1. Since microwaves are used to generate plasma at the same power, the electron concentration is high, so the efficiency of treating exhaust gas is higher. In addition, since the electrodes are abandoned, there is no need to replace the electrodes, the service life is longer, and resources are saved.

[0024] The inlet pipe part includes a metal inlet pipe 3; the metal inlet pipe 3 is fixed on the top of the shielding shell 1; and at least one working air inlet pipe 2 is provided on the side surface of the metal inlet pipe 3. As can be seen from the above structure, the working gas enters the metal inlet pipe 3 from the working air inlet pipe 2 on the side surface of the metal inlet pipe 3 and flows to the outlet pipe part; the metal inlet pipe 3 itself also plays the role of a microwave suppressor.

[0025] The outlet pipe portion includes a metal outlet pipe 4; the metal outlet pipe 4 is fixed to the bottom of the shielding shell 1. From the above structure, it can be seen that the metal outlet pipe 4 also plays the role of a microwave suppressor.

[0026] The microwave-transmissive tube section includes a quartz tube 5; the quartz tube 5 connects the metal inlet tube 3 and the metal outlet tube 4, so that the gas in the input tube cannot enter the shielding shell 1. As can be seen from the above structure, the quartz tube 5 can extend upward from the metal inlet tube 3, so that the working air inlet pipe 2 can be arranged on the quartz tube 5, and the metal inlet tube 3 and the upper part of the quartz tube 5 belong to the inlet tube section; the quartz tube 5 can extend downward from the metal outlet tube 4, so that the metal outlet tube 4 and the lower part of the quartz tube 5 belong to the outlet tube section, and the flame is ejected from the lower part of the quartz tube 5; if the quartz tube 5 does not extend downward from the metal outlet tube 4, the flame is ejected from the metal outlet tube 4.

[0027] Embodiment three:

[0028] See attached Figures 1-2A microwave-based plasma torch comprises a shielding shell 1 and an input pipe; the input pipe penetrates the shielding shell 1; the input pipe comprises an inlet pipe portion located above the shielding shell 1, a microwave-transmissive tube portion located inside the shielding shell 1, and an outlet pipe portion located below the shielding shell 1; a feed port is provided on the shielding shell 1; the feed port is used to input microwaves into the microwave-transmissive tube portion; at least one working air inlet pipe 2 is provided on the inlet pipe portion; the working air inlet pipe 2 is used to input working gas; and the outlet pipe portion is used to output flames. It can be seen from the above structure that the shielding shell 1 generally adopts a metal shell to reduce microwave leakage; the input pipe is a hollow structure, and it is not limited whether it is a regular cross-section or whether it is detachable; the input pipe includes an inlet pipe part located above the shielding shell 1, and the inlet pipe part is used to input working gas, or both working gas and waste gas to be treated; the working gas is generally nitrogen or argon; waste gas, such as waste gas treated by scrubber in CVD equipment in the semiconductor industry; the microwave-permeable tube part inside the shielding shell 1 can transmit microwaves, and is generally made of quartz. The microwave frequency is high and the photon energy is high, which can make the working gas produce high-concentration electrons and decompose the waste gas. In addition, since the plasma temperature is also high, it also promotes the decomposition of the waste gas; the feed port is where microwaves enter the shielding shell 1. The inlet inside the shielding shell 1 can be directly or indirectly connected to the waveguide and the microwave source; at least one working air inlet pipe 2 is provided on the inlet pipe part. If only working gas flows in the inlet pipe part, the working air inlet pipe 2 can be the inlet pipe part itself, directly input from the upper end of the inlet pipe part, or the working air inlet pipe 2 can be a branch pipe separately provided on the outer side of the inlet pipe part; if both working gas and exhaust gas flow in the inlet pipe part, the working air inlet pipe 2 is a branch pipe separately provided on the outer side of the inlet pipe part, and the exhaust gas is directly input from the upper end of the inlet pipe part; the working gas flows from the inlet pipe part to the outlet pipe part, and the generated flame is output from the outlet pipe part; a section of microwave suppressor is provided at the connection part between the inlet pipe part and the outlet pipe part and the shielding shell 1, which is generally a section of metal pipe to reduce the escape of microwaves from the through hole on the shielding shell 1. Since microwaves are used to generate plasma at the same power, the electron concentration is high, so the efficiency of treating exhaust gas is higher. In addition, since the electrodes are abandoned, there is no need to replace the electrodes, the service life is longer, and resources are saved.

[0029] The inlet pipe part includes a metal inlet pipe 3; the metal inlet pipe 3 is fixed on the top of the shielding shell 1; and at least one working air inlet pipe 2 is provided on the side surface of the metal inlet pipe 3. As can be seen from the above structure, the working gas enters the metal inlet pipe 3 from the working air inlet pipe 2 on the side surface of the metal inlet pipe 3 and flows to the outlet pipe part; the metal inlet pipe 3 itself also plays the role of a microwave suppressor.

[0030] The outlet pipe portion includes a metal outlet pipe 4; the metal outlet pipe 4 is fixed to the bottom of the shielding shell 1. From the above structure, it can be seen that the metal outlet pipe 4 also plays the role of a microwave suppressor.

[0031] The microwave-transmissive tube section includes a quartz tube 5; the quartz tube 5 connects the metal inlet tube 3 and the metal outlet tube 4, so that the gas in the input tube cannot enter the shielding shell 1. As can be seen from the above structure, the quartz tube 5 can extend upward from the metal inlet tube 3, so that the working air inlet pipe 2 can be arranged on the quartz tube 5, and the metal inlet tube 3 and the upper part of the quartz tube 5 belong to the inlet tube section; the quartz tube 5 can extend downward from the metal outlet tube 4, so that the metal outlet tube 4 and the lower part of the quartz tube 5 belong to the outlet tube section, and the flame is ejected from the lower part of the quartz tube 5; if the quartz tube 5 does not extend downward from the metal outlet tube 4, the flame is ejected from the metal outlet tube 4.

[0032] The working gas inputted into the input pipe by the working air intake pipe 2 moves in a spiral forward manner. As can be seen from the above structure, the center line of the working air intake pipe 2 can be tilted downward and deviate from the center line of the input pipe, and the air is taken in along the inner wall of the input pipe, so that the working gas will start to flow downward in a spiral along the inner wall of the input pipe, which is conducive to taking away the heat of the input pipe through the working gas, making the equipment more durable and having better heat dissipation.

[0033] It also includes an igniter 6, which is used to generate a tip discharge in the input tube. As can be seen from the above structure, the igniter 6 can be inserted from the inlet tube to generate a tip discharge, instantly stimulate plasma generation, and then be taken away from the inlet tube, which is conducive to reducing the power of the microwave source and saving costs.

[0034] It also includes a compression waveguide 7 and a microwave source 8; the microwave source 8 is connected to the feed port via the compression waveguide 7. As can be seen from the above structure, the compression waveguide 7 increases the energy density of microwaves entering the microwave source 8, thereby increasing the efficiency of generating plasma.

[0035] The microwave is input from the feed port, passes through the center of the microwave-transmitting tube, and then is reflected by the inner wall of the shielding shell 1. The distance from the inner wall of the shielding shell 1 to the center of the microwave-transmitting tube is 0.5*n+0.25 times the wavelength, where n is a non-negative integer. It can be seen from the above structure that this size makes the electric field in the center of the microwave-transmitting tube the strongest, thereby improving the efficiency of generating plasma.

[0036] There are two working air intake pipes 2, which are evenly surrounded on the intake pipe portion.

[0037] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A microwave-based plasma torch, characterized in that: The invention comprises a shielding shell (1) and an input pipe; the input pipe passes through the shielding shell (1); the input pipe comprises an inlet pipe portion located above the shielding shell (1), a microwave-permeable tube portion located inside the shielding shell (1), and an outlet pipe portion located below the shielding shell (1); a feed port is provided on the shielding shell (1); the feed port is used to input microwaves into the microwave-permeable tube portion; the inlet pipe portion is provided with at least one working air inlet pipe (2); the working air inlet pipe (2) is used to input working gas; the outlet pipe portion is used to output flame; the inlet pipe portion comprises a metal inlet pipe (3); the metal inlet pipe (3) is fixed to the top of the shielding shell (1); at least one working air inlet pipe (2) is provided on the side surface of the metal inlet pipe (3); the outlet pipe portion comprises a metal outlet pipe (4); the metal outlet pipe (4) is fixed to the bottom of the shielding shell (1). The microwave-transmitting tube portion comprises a quartz tube (5); the quartz tube (5) is connected to a metal inlet tube (3) and a metal outlet tube (4) so ​​that the gas in the inlet tube cannot enter the shielding shell (1); the working gas input into the working inlet tube (2) moves in a spiral forward manner; the device also comprises a lighter (6); the lighter (6) is used to generate a tip discharge in the inlet tube; the device also comprises a compression waveguide (7) and a microwave source (8); the microwave source (8) is connected to the feed port through the compression waveguide (7); the microwave is input from the feed port, passes through the center of the microwave-transmitting tube portion, and then is reflected by the inner wall of the shielding shell (1); the distance from the inner wall of the shielding shell (1) to the center of the microwave-transmitting tube portion is (0.5*n+0.25) times the wavelength, where n is a non-negative integer; there are two working inlet tubes (2), which are evenly surrounded on the inlet tube portion.

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