CN111203164B - Gas phase reaction buffer chamber based on atmospheric pressure microwave plasma torch - Google Patents
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
- B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
- B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
- B01J19/122—Incoherent waves
- B01J19/126—Microwaves
Abstract
A gas phase reaction buffer chamber based on an atmospheric pressure microwave plasma torch belongs to the application fields of plasma technology and environmental chemistry. The device comprises a gas injection part, a buffer chamber, a barometer and an exhaust pump, wherein the buffer chamber is arranged above the gas injection part, and the top of the buffer chamber is connected with the barometer and the exhaust pump. The gas injection part comprises a rectangular waveguide, a movable metal baffle, a buffer chamber flange and a discharge tube, wherein working gas is introduced into the discharge tube to form a vortex gas flow field, and the working gas in the discharge tube is ionized to form microwave plasma discharge under the induction of a microwave electric field. And the buffer chamber maintains a certain working air pressure, so that the plasma torch maintains a stable discharge form. The invention can increase the plasma density and the electron temperature in the interaction area of the plasma and the gas, is beneficial to further improving the chemical reaction rate of the plasma gas phase reaction, and simultaneously ensures that the gas introduced into the discharge tube can fully participate in the plasma chemical reaction.
Description
Technical Field
The invention relates to a gas phase reaction buffer chamber based on an atmospheric pressure microwave plasma torch, belonging to the application fields of plasma technology and environmental chemistry.
Background
The gas temperature of the electrodeless pollution plasma generated by the atmospheric pressure microwave plasma torch is usually in the range of 3000-6000K, and the electron density is 10 14 cm -3 The high-activity plasma atmosphere is very suitable for chemical gas phase reaction, and the higher energy density ensures that the gas flux is very large>100m 3 And/h) the plasma can maintain a stable discharge state. In addition, considering the advantages of high energy utilization rate (more than 60%) of microwave plasma and no need of vacuum system when working under normal pressure, the method is not only in gas modification, for example, removal of perfluorinated greenhouse gas and CO from the aspects of practical effectiveness and economy 2 The method has the advantages of converting the gas into the synthesis gas, preparing hydrogen from hydrocarbon, and the like, and has wide application prospect in the fields of plasma-assisted combustion, chemical vapor deposition synthesis of advanced materials, and the like. As a dual-cavity excited microwave plasma torch proposed in patent CN207070436U, a technical means of generating plasma by employing compressed waveguide cross section, single-mode standing wave excitation, vortex air flow field control, and dual-cavity coupling synergy has been disclosed, and stable atmospheric pressure microwave plasma torches have been experimentally realized that achieve post-discharge afterglow extension spaces exceeding 40 cm long in a discharge tube having a diameter of 3 cm.
In the scientific research and industrial production of the product,gas phase reactions in a plasma atmosphere generated by an atmospheric pressure microwave plasma torch are often utilized to carry out some practical applications such as the removal of perfluorinated greenhouse gases, CO 2 The conversion of the gas into synthesis gas, the production of hydrogen from hydrocarbons, and the like. Depending on the nature of the atmospheric pressure microwave plasma torch, the introduction of the reactive precursor is typically done in the plasma excitation region and the plasma afterglow region, for example, patent CN207307576U discloses an application where mixing of industrial tail gas in the afterglow region of the atmospheric pressure microwave plasma torch to effect degradation and thereby reduce emissions, as compared to premixing of the reactant precursor into the carrier gas where it is ionized, excited and decomposed will be more conducive to the chemical gas phase reaction, mainly because the active species in the plasma excitation region and the high energy energetic particle number density are more than in the plasma afterglow region, and thus in some gas phase chemical reactions the precursor is often premixed into the carrier gas to generate plasma by microwave coupling excitation region discharge rather than into the plasma afterglow region. At the same time, this requirement for plasma torch discharge stability control is greatly increased because mixing reactive precursor reactant gases into the carrier gas at atmospheric pressure tends to have a significant impact on discharge stability. The atmospheric pressure microwave plasma torch stabilizes the plasma discharge through the vortex gas flow field, and when the working gas is injected into the discharge tube, a gas insulating layer is formed to isolate a high temperature region of the plasma in the center of the discharge tube from the wall of the discharge tube, so that a space region without filling the plasma is naturally formed in the discharge tube, and accordingly, a part of mixed gas injected into the discharge tube passes through the space region and is not directly discharged out of the discharge tube without participating in the gas phase chemical reaction of the plasma, so that the improvement of the reaction efficiency is limited, for example, the degradation rate of industrial tail gas is removed when the atmospheric pressure microwave plasma torch is applied, and the conversion rate in gas modification application is limited by the existence of the gas insulating layer. The proposal solves the technical problem faced at present. The proposal is that a reaction buffer chamber is added at the outlet of the atmospheric pressure microwave plasma torch, so thatThe outlet of the discharge tube extending into the reaction buffer chamber forms a plasma expansion area and completely covers the outlet of the discharge tube, and the gas flowing out of the discharge tube can be fully mixed with the plasma in the area to generate physical-chemical reaction; in addition, the outer wall of the reaction buffer chamber adopts a cylindrical metal barrel with a certain wall thickness to form a waveguide structure, so that the electric field intensity of an excited electromagnetic mode in the waveguide structure is enhanced in the axial direction of a discharge tube extending into the buffer chamber, thereby increasing the electron density and the electron temperature in a mixing region, greatly improving the chemical reaction rate and corresponding technical indexes such as degradation rate or conversion rate in some applications. Although there is a reaction buffer chamber in many practical applications using plasma technology, the buffer chambers in these disclosed inventions only serve to isolate the mixed gas undergoing the gas phase chemical reaction from the outside, and do not exhibit the function and application function of improving the reaction efficiency described in our invention.
The application of industrial tail gas treatment by utilizing an atmospheric pressure microwave plasma torch is a typical example realized by a plasma gas phase chemical reaction, the degradation rate achieved is a technical index which is considered first, meanwhile, the energy efficiency is another index for measuring the technology, and experiments prove that the energy efficiency is improved by the optimized design of a gas buffer chamber under the precondition of achieving the degradation rate required by emission, and the method has a very large improvement space. For example, in the aspect of removing perfluorinated compound gas, besides the working condition of the atmospheric pressure microwave plasma torch, the gas buffer chamber which is in butt joint with the atmospheric pressure plasma torch is introduced, and the removal rate under the condition of the actual working condition is 99% through the reasonable design of the structure of the gas buffer chamber and the optimization of specific parameters. Experimental data obtained in a specific application are presented in the specific examples of the present specification.
Disclosure of Invention
The invention provides a solution method for improving the performance of the conventional atmospheric pressure microwave plasma torch in order to improve the reaction efficiency, aiming at the technical problems existing in the practical application of the conventional atmospheric pressure microwave plasma torch in chemical gas phase reaction.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the gas-phase reaction buffer chamber based on the atmospheric pressure microwave plasma torch comprises a gas injection part 1, a buffer chamber 2, a barometer 3 and an exhaust pump 4, wherein the buffer chamber 2 is arranged above the gas injection part 1, and the top of the buffer chamber 2 is connected with the barometer 3 and the exhaust pump 4. The gas injection part 1 comprises a rectangular waveguide 11, a movable metal baffle 12, a buffer chamber flange 13, and a discharge tube 14. The buffer chamber 2 comprises an outer sleeve 21, a metal cylinder 22, a buffer chamber cover 23, an exhaust port 24, an air pressure measuring port 25 and an epitaxial tube 26.
The movable metal baffle 12 is arranged at one end of the rectangular waveguide 11, microwaves generated by the microwave generator are introduced into the rectangular waveguide 11 by the transmission device, and under the reflection of the end face of the waveguide formed by the movable metal baffle 2, the microwaves generate TE in the rectangular waveguide 11 01 The electric field in the waveguide is perpendicular to the broad face of the rectangular waveguide 11. A pair of waveguide wide wall surfaces corresponding to the maximum value of the electric field intensity are provided with holes, a discharge tube 14 vertically penetrating through the wide surface of the rectangular waveguide 11 is arranged, the discharge tube 14 is positioned in an atmospheric pressure microwave plasma torch waveguide excitation area, working gas is introduced into the discharge tube 14 through the gas injection component 1 to form a vortex gas flow field distributed in the radial direction, and the working gas introduced into the discharge tube 14 is ionized under the induction of the microwave electric field to form microwave plasma discharge under the atmospheric pressure.
One end face of the buffer chamber 2 is vertically butted with the wide wall face of the rectangular waveguide 11 through the buffer chamber flange 13, so that a discharge tube 14 vertical to the rectangular waveguide 11 extends into the buffer chamber 2 for a certain depth distance through a discharge tube mounting hole 132, and a microwave plasma torch generated in the discharge tube 14 is introduced into the gas buffer chamber 2; the extension tube 26 can be inserted into the buffer chamber 2 by inserting an extension tube 26 having an inner diameter slightly larger than the outer diameter of the discharge tube into the end of the discharge tube 14. The other end of the gas buffer chamber outer sleeve 21 is connected with the inlet of the exhaust pump 4 through an exhaust port 24 on the buffer chamber cover 23, and a gas pressure measuring port 25 on the buffer chamber cover 23 is externally connected with a gas pressure gauge 3 for monitoring the gas pressure in the buffer chamber, so that the total gas flow is controlled on line to keep a proper working gas pressure in the buffer chamber 2, and the gas pressure in the buffer chamber 2 can be controlled by adjusting and setting the flow of the input gas and the flow of the exhaust gas.
The metal cylinder 22 forms the outermost layer of the buffer chamber 2 and is fixed between the buffer chamber flange 13 and the buffer chamber cover 23.
The total length of the outer sleeve 21 of the gas buffer chamber is 3 times longer than the extension length of the extension tube 26 or the discharge tube 14 in the gas buffer chamber by the distance of the diameter D1 of the discharge tube, and the inner diameter D2 of the outer sleeve 21 is more than 2 times larger than the outer diameter D1 of the discharge tube 14; the length of the discharge tube 14 extending into the gas buffer chamber is set to be 1-5 distances from the diameter D1 of the discharge tube 14; the value of the outer diameter D1 of the discharge tube 14 is in the range of 0.05-0.38 times of the width of the rectangular waveguide 11; the diameter D3 of the metal cylinder 22 is larger than the outer diameter of the gas buffer outdoor sleeve 21 and smaller than 22.98X10 9 The interval of the calculated value of/f cm, where f is the microwave frequency, for example, 9.38 cm for microwaves of the frequency 2.45GHz, 0.5 to 3.4 cm for the outer diameter D1 of the discharge vessel 14, and 25.11 cm for microwaves of the frequency 915MHz, 1.2 to 9.2 cm for the outer diameter D1 of the discharge vessel 14.
The wall of the buffer outdoor sleeve 21 can be made of insulating and heat-resistant materials.
The discharge tube 14 is made of a heat-resistant insulating material such as a quartz tube or a ceramic tube, the epitaxial tube 26 is made of a heat-resistant insulating material such as a ceramic material or a quartz material, the epitaxial tube 26 and the discharge tube 14 can be made of the same or different materials, and when the epitaxial tube 26 and the discharge tube 14 are made of the same material, a complete through tube with proper length is adopted; when the epitaxial tube 26 and the discharge tube 14 are made of different materials, the epitaxial tube 26 and the discharge tube 14 are in butt joint at the interface of the buffer chamber 2 and the plasma torch waveguide, if the discharge tube 14 adopts a quartz tube and the epitaxial tube 26 extending into the buffer chamber adopts a ceramic tube, the inner diameter of the ceramic tube is required to be slightly larger than the outer diameter of the quartz tube, so that the two tubes are in butt joint together to form tight butt joint.
The specific values of the structural parameters of the gas buffer chamber 2 are determined by considering the condition of the total flow of the working gas, and the working gas pressure in the buffer chamber 2 is ensured to be kept in the range of 0.6-1.2 atm, so that the plasma torch maintains a stable discharge form, and the disturbance of the discharge stability of the plasma torch caused by the introduction of the gas buffer chamber is eliminated.
The gas buffer chamber flange (13) and the buffer chamber sealing cover 23 are made of metal.
Further, since a large amount of heat is generated by the plasma torch discharge, a cooling water jacket may be added to the gas buffer chamber cover 23, and cooling is performed before the gas discharge and the gas pressure measurement to effectively protect the exhaust pump 4 or the barometer 3.
The beneficial effects of the invention are as follows:
(1) The extension tube of the plasma torch discharge tube is introduced into the gas buffer chamber, and the distribution of the gas flow field in the gas buffer chamber is optimized by setting and adjusting parameters of the gas buffer chamber, so that the interaction area of the extended plasma and the gas formed at the end part of the extension tube is increased, and the chemical reaction rate of the plasma gas phase reaction is improved.
(2) When the outer sleeve of the gas buffer chamber adopts a metal pipe wall, a cylindrical resonant cavity is formed, microwaves are coupled to the gas buffer chamber through the connection part of the gas buffer chamber and the plasma torch waveguide tube to establish an electromagnetic mode, and the axial field intensity of an electric field along the extension tube of the discharge tube is increased in the electromagnetic mode, so that the plasma density and the electron temperature in an interaction area of plasma and gas are increased, and the chemical reaction rate of the plasma gas phase reaction is further improved.
Drawings
FIG. 1 shows the degradation of CF in a reaction buffer chamber according to the present invention 4 A Degradation Rate (DRE) change curve graph with microwave power, which is obtained through experimental measurement;
FIG. 2 shows SF degradation using the reaction buffer chamber of the present invention 6 Obtained by experimental measurementA plot of Degradation Rate (DRE) achieved as a function of microwave power;
FIG. 3 is a schematic diagram of a gas buffer chamber;
FIG. 4 is a schematic diagram of a buffer chamber cover;
FIG. 5 is a schematic view of a flange structure of a buffer chamber;
in the figure: 1 a gas injection member; 2 a buffer chamber; 3, an air pressure gauge; 4, an exhaust pump; 11 rectangular waveguide; 12 a movable metal barrier; 13 a buffer chamber flange; 14 discharge tube; an outer sleeve 21; 22 metal cylinders; 23 buffer chamber cover; 24 exhaust ports; 25. an air pressure measuring port; an epitaxial tube 26; 41 exhaust pump outlet; 131 the outer sleeve mounting groove 1;132, and 231 outer sleeve mounting slots.
Detailed Description
The invention will be further illustrated with reference to specific examples. These examples are only for illustrating the present invention and are not limited in the scope of application of the present invention. Further, after reading what is described herein, those skilled in the art may make various changes or modifications to the present invention, and these equivalents are also within the scope of the claims of the present application. The structure of the gas buffer chamber provided by the invention is not only used for removing and degrading perfluorinated compounds, but also suitable for treating other industrial exhaust by adopting an atmospheric pressure plasma technology.
With the development of industry, perfluorinated gases are widely used in the semiconductor industry and the power industry in their low toxicity and stable chemical properties. CF (compact flash) 4 And SF (sulfur hexafluoride) 6 Are typical perfluorinated gases that have a strong infrared absorption capacity, global warming potential indexes GWP100 of 6500 and 8000, respectively, and their natural decomposition in the atmosphere results in a relatively long residence time. CF (compact flash) 4 The gas is an important raw material gas for completing etching process and chemical vapor deposition processing in the semiconductor industry, and SF 6 Is widely applied to gas insulated switch GIS and SF in the power industry due to excellent insulativity and good arc extinguishing performance 6 Load switching device, SF 6 Medium-high voltage equipment such as insulated transmission lines GIL, transformers, etc., while due toThe high-speed development of the power industry in China has the greatest proportion and SF in the same industry worldwide 6 And the discharge amount of (2) is also increasing. Thus creating CF 4 And SF (sulfur hexafluoride) 6 The gas grows faster and faster in the atmosphere, so CF 4 And SF (sulfur hexafluoride) 6 The influence on the greenhouse effect is already not so small. The "united nations climate change schema convention in kyoto" has agreed to prevent the adverse effects of greenhouse gases on climate and economic problems, and control of perfluorinated gas emissions is an important environmental issue that needs to be addressed.
Currently, methods for reducing the emission of perfluorinated gases are: searching for alternative compounds, optimizing the process, recovering and recycling, and removing the abatement. The removal of abatement is a preferred option in industry to control emissions in view of economics and process maturity. The application of plasma technology in exhaust gas removal is considered a promising approach compared to conventional combustion decomposition methods. Wherein, the discharge condition of the atmospheric pressure microwave plasma torch in the practical application of industrial tail gas treatment and gas modification can be optimized and the simultaneous process regulation is possible because the electrode is not needed for the generation of the microwave plasma while the discharge process is kept in a controllable stable state, thereby having a large lifting space in the aspects of improving the removal rate and the energy efficiency, which is shown in CF 4 And SF (sulfur hexafluoride) 6 The outstanding effect of the degradation of typical greenhouse gases is verified. The following two examples are two application effects that are developed in connection with our proposed chemical vapor reaction buffer chamber in the application of an atmospheric pressure microwave plasma torch.
The patent CN207070436U proposes a double-cavity excited atmospheric pressure microwave plasma torch based on the specific structure and working principle of the atmospheric pressure microwave plasma torch, and the gas phase reaction buffer chamber comprises a gas injection part 1, a buffer chamber 2, a barometer 3 and an exhaust pump 4. The gas injection part 1 comprises a rectangular waveguide 11, a movable metal baffle 12, a buffer chamber flange 13 and a discharge tube 14, and the buffer chamber 2 comprises an outer sleeve 21, a metal cylinder 22, a buffer chamber cover 23, an exhaust port 24, a gas pressure measuring port 25 and an epitaxial tube 26. The buffer chamber 2 is arranged above the gas injection component 1, and the top of the buffer chamber 2 is connected with the barometer 3 and the exhaust pump 4.
The movable metal baffle 12 is arranged at one end of the rectangular waveguide 11, microwaves generated by the microwave generator are introduced into the rectangular waveguide 11 by the transmission device, and under the reflection of the end face of the waveguide formed by the movable metal baffle 2, the microwaves generate TE in the rectangular waveguide 11 01 The electric field in the waveguide is perpendicular to the broad face of the rectangular waveguide 11. A pair of waveguide wide wall surfaces corresponding to the maximum value of the electric field intensity are provided with holes, a discharge tube 14 vertically penetrating through the wide surface of the rectangular waveguide 11 is arranged, the discharge tube 14 is positioned in an atmospheric pressure microwave plasma torch waveguide excitation area, working gas is introduced into the discharge tube 14 through the gas injection component 1 to form a vortex gas flow field distributed in the radial direction, and the working gas introduced into the discharge tube 14 is ionized under the induction of the microwave electric field to form microwave plasma discharge under the atmospheric pressure.
One end face of the buffer chamber 2 is vertically butted with the wide wall face of the rectangular waveguide 11 through the buffer chamber flange 13, so that the discharge tube 14 vertical to the rectangular waveguide 11 extends into the buffer chamber 2 by a certain depth distance through the discharge tube mounting hole 132, and a microwave plasma torch generated in the discharge tube 14 is introduced into the gas buffer chamber 2; the extension tube 26 can be inserted into the buffer chamber 2 by inserting an extension tube 26 having an inner diameter slightly larger than the outer diameter of the discharge tube into the end of the discharge tube 14. The other end of the gas buffer chamber outer sleeve 21 is connected with the inlet of the exhaust pump 4 through an exhaust port 24 on the buffer chamber cover 23, and a gas pressure measuring port 25 on the buffer chamber cover 23 is externally connected with a gas pressure gauge 3 for monitoring the gas pressure in the buffer chamber, so that the total gas flow is controlled on line to keep a proper working gas pressure in the buffer chamber 2, and the gas pressure in the buffer chamber 2 can be controlled by adjusting and setting the flow of the input gas and the flow of the exhaust gas.
The metal cylinder 22 forms the outermost layer of the buffer chamber 2 and is fixed between the buffer chamber flange 13 and the buffer chamber cover 23.
The total length of the outer sleeve 21 of the gas buffer chamber is 3 times longer than the extension length of the extension tube 26 or the discharge tube 14 in the gas buffer chamber by the distance of the diameter D1 of the discharge tube, and the inner diameter D2 of the outer sleeve 21 is more than 2 times larger than the outer diameter D1 of the discharge tube 14; the length of the discharge tube 14 extending into the gas buffer chamber is set to be 1-5 distances from the diameter D1 of the discharge tube 14; the diameter D3 of the metal cylinder 22 is larger than the outer diameter of the gas buffer outdoor sleeve 21 and smaller than 22.98X10 9 Calculated interval of/f cm, where f is microwave frequency. 22.98X10 for microwaves at a frequency of 2.45GHz 9 The calculated value of/f is 9.38 cm, the outer diameter D1 of the discharge vessel 14 is 0.5 to 3.4 cm, and 22.98X10 for a microwave of 915MHz frequency 9 The calculated value of/f is 25.11 cm and the outer diameter D1 of the discharge vessel 14 is 1.2 to 9.2 cm.
The wall of the buffer outdoor sleeve 21 is made of insulating and heat-resistant materials, in particular quartz glass or ceramic materials.
The discharge tube 14 is made of a heat-resistant insulating material such as a quartz tube or a ceramic tube, and the epitaxial tube 26 is made of a heat-resistant insulating material such as a ceramic material or a quartz material.
The volume of the gas buffer chamber 2 is required to ensure that the working gas pressure in the buffer chamber 2 is kept within the range of 0.6-1.2 atm under the condition of the total flow of the working gas, so that the plasma torch maintains a stable discharge form, and the disturbance of the discharge stability of the plasma torch due to the introduction of the gas buffer chamber is eliminated.
The gas buffer chamber flange 13 and the buffer chamber cover 23 are made of metal such as aluminum, aluminum alloy, copper or stainless steel.
Example 1
The invention discloses a double-cavity excited atmospheric pressure microwave plasma torch and a gas phase reaction buffer chamber for CF (compact flash) by using a patent CN207070436U 4 Experimental results of degradation. Under the condition of taking nitrogen as background gas, starting a microwave plasma torch, setting the gas flow to 15 liters/min and the microwave power to 1000W, so that the plasma discharge is kept stable, and mixing CF in the plasma carrier gas 4 Gas, airThe concentration of the body gradually increases from the minimum value to the set value, and the discharge is kept stable. Measurement results in CF 4 The ratio of carrier gas mixed with nitrogen is 3000ppm and 4000ppm respectively, and the degradation rate DRE value is changed trend along with the microwave power under the condition that the total gas flow is 15 liters/min, wherein the DRE is defined as follows:
wherein C is before And Cafter representing CF before and after plasma removal, respectively, obtained from FTIR spectra 4 Is a concentration of (3). FIG. 1 shows a CF 4 When the concentration is 3000ppm and 4000ppm respectively, the atmospheric pressure microwave plasma torch excited by the double cavities and provided by the patent CN207070436U and the degradation CF of the gas phase reaction buffer chamber provided by the invention are applied 4 The trend of the measured DRE value of (c) with increasing microwave power from 1200W to 2000W.
Example 2
SF is carried out by applying the atmospheric pressure microwave plasma torch excited by the patent CN207070436U and the gas phase reaction buffer chamber 6 Experimental data of degradation. Under the condition that nitrogen is used as background gas, the microwave plasma torch is started, the total gas flow is gradually switched from nitrogen to oxygen under the condition of keeping the total gas flow to be 15 liters/min unchanged, and finally the microwave plasma torch is discharged under the pure oxygen carrier gas condition. Setting gas flow rate of 15L/min and microwave power of 1000W to make plasma discharge stable, mixing SF in plasma carrier gas 6 The concentration of the gas gradually increases from a small value to a set value, and the discharge is kept stable. Measurement results in SF 6 The ratio of the mixed oxygen carrier gas was 10000ppm,20000ppm,30000ppm, and 4000ppm, respectively, and the total gas flow was 15 liters/min, and the degradation rate DRE value was varied according to the microwave power, wherein the DRE was defined as the formula in example 1. FIG. 2 shows SF 6 When the concentrations are 1000,2000,3000,4000ppm respectively, the double-cavity excited atmospheric pressure microwave plasma torch and the gas phase reaction of the invention are provided by the patent CN207070436UStress buffer chamber degradation CF 6 The trend of the measured DRE value of (c) with increasing microwave power from 1200W to 2400W.
The examples described above represent only embodiments of the invention and are not to be understood as limiting the scope of the patent of the invention, it being pointed out that several variants and modifications may be made by those skilled in the art without departing from the concept of the invention, which fall within the scope of protection of the invention.
Claims (5)
1. The gas-phase reaction buffer chamber based on the atmospheric pressure microwave plasma torch is characterized by comprising a gas injection component (1), a buffer chamber (2), a barometer (3) and an exhaust pump (4), wherein the buffer chamber (2) is arranged above the gas injection component (1), and the top of the buffer chamber (2) is connected with the barometer (3) and the exhaust pump (4); the gas injection part (1) comprises a rectangular waveguide (11), a movable metal baffle plate (12), a buffer chamber flange (13) and a discharge tube (14); the buffer chamber (2) comprises an outer sleeve (21), a metal cylinder (22), a buffer chamber sealing cover (23), an exhaust port (24) and an air pressure measuring port (25);
the movable metal baffle (12) is arranged at one end of the rectangular waveguide (11), microwaves generated by the microwave generator are introduced into the rectangular waveguide (11) by the transmission device, and under the reflection of the end face of the waveguide formed by the movable metal baffle (2), the microwaves generate TE in the rectangular waveguide (11) 01 Standing wave mode, electric field in the waveguide is vertical to wide surface of rectangular waveguide (11); a pair of waveguide wide wall surfaces corresponding to the maximum value of the electric field strength are provided with holes, a discharge tube (14) vertically penetrating through the wide surface of the rectangular waveguide (11) is arranged, the discharge tube (14) is positioned in an atmospheric pressure microwave plasma torch waveguide excitation area, working gas is introduced into the discharge tube (14) through a gas injection component (1) to form a vortex gas flow field distributed in the radial direction, and the working gas introduced into the discharge tube (14) is ionized under the induction of the microwave electric field to form microwave plasma discharge under the atmospheric pressure;
one end face of the buffer chamber (2) is vertically butted with the wide wall face of the rectangular waveguide (11) through a buffer chamber flange (13), the discharge tube (14) stretches into the buffer chamber (2) through a discharge tube mounting hole (132), a microwave plasma torch generated in the discharge tube (14) is introduced into the gas buffer chamber (2), and the length of the discharge tube (14) stretching into the gas buffer chamber is set to be 1-5 distances from the diameter D1 of the discharge tube (14); the other end of the gas buffer chamber outside sleeve (21) is connected with the inlet of the exhaust pump (4) through an exhaust port (24) on the buffer chamber cover (23); the air pressure measuring port (25) on the buffer chamber sealing cover (23) is externally connected with an air pressure meter (3) for monitoring the air pressure in the buffer chamber, and the air pressure in the buffer chamber (2) is controlled by adjusting and setting the flow of the input air and the flow of the exhaust air so that the plasma torch can keep a stable discharge form;
the metal cylinder (22) forms the outermost layer of the buffer chamber (2) and is fixed between the buffer chamber flange (13) and the buffer chamber sealing cover (23);
the total length of the outer sleeve (21) of the gas buffer chamber is 3 times longer than the extension length of the discharge tube (14) in the gas buffer chamber by the distance of the diameter D1 of the discharge tube, and the inner diameter D2 of the outer sleeve (21) is more than 2 times larger than the outer diameter D1 of the discharge tube (14); the value of the outer diameter D1 of the discharge tube (14) is in the range of 0.05-0.38 times of the width of the rectangular waveguide (11); the diameter D3 of the metal cylinder (22) is larger than the outer diameter of the gas buffer outdoor sleeve (21) and smaller than 22.98X10 9 Calculated interval of/f cm, where f is the microwave frequency.
2. A gas phase reaction buffer chamber based on an atmospheric pressure microwave plasma torch according to claim 1, wherein the working gas pressure in the gas buffer chamber (2) is maintained in the range of 0.6-1.2 atmospheres.
3. The gas phase reaction buffer chamber based on the atmospheric pressure microwave plasma torch according to claim 1, wherein the discharge tube (14) is made of a quartz tube or a ceramic tube heat-resistant insulating material, and the port shape of the discharge tube (14) extending into the buffer chamber (2) is an opening formed by cutting the discharge tube vertically and regularly with the tube, or an opening with a flaring shape and a closing shape.
4. The gas phase reaction buffer chamber based on the atmospheric pressure microwave plasma torch according to claim 1, wherein the gas buffer chamber flange (13) and the buffer chamber cover (23) are both made of metal.
5. A gas phase reaction buffer chamber based on an atmospheric pressure microwave plasma torch according to claim 1, wherein,
the plasma torch discharges and generates a large amount of heat, a cooling water jacket is added on the gas buffer chamber cover (23), and the cooling is performed before gas discharge and gas pressure measurement, so that the exhaust pump (4) and the barometer (3) are protected.
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| CN112439375B (en) * | 2020-11-06 | 2022-06-07 | 天津全和诚科技有限责任公司 | Coil pipe type microwave reactor |
| CN113401868B (en) * | 2021-08-04 | 2023-06-09 | 大连理工大学 | Device for preparing hydrogen and sulfur by decomposing hydrogen sulfide by utilizing atmospheric pressure microwave plasma torch |
| CN113587084B (en) * | 2021-08-04 | 2022-05-13 | 大连理工大学 | Device for enhancing combustion by utilizing microwave plasma torch |
| CN114538373A (en) * | 2022-01-28 | 2022-05-27 | 大连理工大学 | Hydrogen production system and method for decomposing alcohols by microwave plasma under normal pressure |
| CN115584492A (en) * | 2022-10-19 | 2023-01-10 | 国网安徽省电力有限公司马鞍山供电公司 | Method for generating high-density atmospheric pressure fluorocarbon plasma jet |
| CN115646126B (en) * | 2022-11-10 | 2023-08-01 | 杭州慕皓新能源技术有限公司 | Microwave device for cracking and converting gas |
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