A low-temperature plasma disproportionation reaction unit, disproportionation reactor and disproportionation method

Abstract

The present invention discloses a low-temperature plasma disproportionation reaction unit, which includes a U-shaped tube, and a double dielectric rod-cylinder type barrier discharge structure arranged on its straight pipe section, and a seal combining a double ceramic sheet and an organic insulating medium is provided at the top. A disproportionation reactor based on the reaction unit is also proposed, which mainly includes a filter, a flow controller, a first oxygen analyzer, a first buffer tank, a second oxygen analyzer, a low-temperature plasma disproportionation reaction unit, and a second buffer tank that are sequentially connected in series and located in a heat preservation layer. Finally, a disproportionation reaction method based on the disproportionation reactor is also proposed, which mainly includes purification, flow control, oxygen analysis to eliminate hydrogen explosion, low-temperature plasma disproportionation reaction, and gas component analysis to evaluate the reaction efficiency. The disproportionation reaction unit, reactor, and reaction method can achieve low-temperature disproportionation reaction, without the problems of noble metal catalyst shedding and tritium-containing waste generation, and at the same time have high conversion efficiency, fast reaction speed, and low operating cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen isotope exchange, and particularly relates to a low-temperature plasma disproportionation reaction unit and a disproportionation reactor, and also relates to a disproportionation method based on the device. Background Art

[0002] The hydrogen isotope disproportionation technology is widely used in the field of hydrogen isotope separation, and has great application prospects in the fields of tritium separation and purification in fusion reactors and fusion-fission hybrid reactors. For the hydrogen isotopes in a tritium factory or a tritium process system, in order to achieve the separation of hydrogen isotopes and obtain high-quality components such as tritium and deuterium, it is necessary to use systems such as cryogenic distillation or chromatographic separation to separate and purify them. During this process, there will be a certain amount of gaseous substances such as hydrogen deuteride (HD), hydrogen tritide (HT), and deuterium tritide (DT). In order to improve the separation efficiency, it is necessary to convert them into H2, D2, and T2 as much as possible to increase the molecular weight difference between hydrogen isotopes, thereby improving the separation efficiency. The function of the hydrogen isotope disproportionation reactor is to convert gaseous substances such as hydrogen deuteride (HD), hydrogen tritide (HT), and deuterium tritide (DT) into H2, D2, and T2. The specific disproportionation reaction process is shown in Equations (1) to (3):

[0003]

[0004] The atmosphere after disproportionation will be transported back to the cryogenic distillation and chromatographic separation systems. Currently, the hydrogen isotope disproportionation reaction is mainly carried out by thermal catalysis, that is, a platinum or palladium-based catalyst is added to a fixed-bed reactor, and the atmosphere reaction of Equations (1) to (3) is carried out using the catalyst at an environment of about 370K. Currently, the following disadvantages of this technology need to be solved: (1) The working temperatures of the cryogenic distillation and chromatographic separation systems are generally below about 20K and 77K. For the catalytic reaction, the temperature is too low and the reaction rate is too slow. Therefore, the thermal catalysis technology needs to heat the gas to 370K and then lower the temperature to low temperature after the reaction, which will consume a large amount of energy; (2) The hydrogen isotope disproportionation reaction is an exothermic reaction, and the lower the temperature, the higher the conversion rate. Therefore, it is beneficial to the reaction at 77K and below. However, the low temperature causes a significant decrease in the activity of the catalyst, and conventional catalysts cannot achieve this, so the conversion rate of this reaction cannot be increased; (3) The catalyst is prone to deactivation under long-term action, and the cost of replacing the catalyst is high and it is a tritium-containing waste, which is difficult to treat subsequently.

[0005] Based on this, in order to make the disproportionation reaction have a high efficiency and conversion rate, and at the same time to reduce the reaction cost, it is necessary to optimize the disproportionation reaction process. Summary of the Invention

[0006] In view of the disadvantages of the thermal catalytic disproportionation reactor, such as a narrow reaction temperature adaptation range, a long reaction equilibrium time, high costs caused by the extensive use of noble metal catalysts, and the generation of waste, the low-temperature plasma technology is combined with the disproportionation reaction herein. Also, fully considering the problems of uneven discharge caused by the failure of the outer electrode due to low-temperature icing, and the explosiveness, leakage, and diffusion of the hydrogen isotope exchange reaction, a disproportionation reaction unit, a disproportionation reactor, and a disproportionation method are proposed, enabling the disproportionation reactor to obtain a wider temperature range, a faster reaction rate, and less tritium-containing treatment waste. Using this technology, high-efficiency disproportionation without a catalyst can be achieved.

[0007] To achieve the goal, the following technical solutions are adopted:

[0008] A low-temperature plasma disproportionation reaction unit includes a U-shaped tube, and the U-shaped tube is made of high-strength ceramic or high-strength quartz glass. Columnar inner electrodes are coaxially arranged inside the first straight tube section and the second straight tube section of the U-shaped tube. The inner electrode includes a columnar metal electrode and an alumina coating covering the surface of the metal electrode. Outer electrodes are coaxially arranged at positions corresponding to the columnar inner electrodes outside the first straight tube section and the second straight tube section, and the outer electrodes are grounded. Seals are provided at the ends of the first straight tube section and the second straight tube section. Part of the upper end of the inner electrode is encapsulated in the seal, and the upper end of the inner electrode is connected to an external low-temperature plasma power supply. An air inlet is provided in the first straight tube section, and an air outlet is provided in the second straight tube section.

[0009] Optionally, the seal is a seal combining double ceramic sheets and an organic insulating medium, and the double ceramic sheets are respectively located above and below the organic insulating medium.

[0010] Optionally, the metal electrode is a columnar copper electrode with a thinner upper part and a thicker lower part, the outer electrode is a cylindrical stainless steel mesh, the thicker part of the copper electrode corresponds to the outer electrode, and the top of the thicker part is lower than the air inlet and the air outlet.

[0011] Optionally, the input voltage, frequency, center frequency, and duty cycle of the low-temperature plasma power supply are adjustable.

[0012] A low-temperature plasma disproportionation reactor, comprising a filter, a mass flow controller, a first oxygen analyzer, a first buffer tank, a second oxygen analyzer, a low-temperature plasma disproportionation reaction unit, and a second buffer tank that are sequentially connected and located inside a thermal insulation layer; the low-temperature plasma disproportionation reaction unit is one, or multiple units connected in series, or multiple units connected in parallel; the thermal insulation layer is a closed cavity structure, and the thermal insulation layer is in a vacuum state during the disproportionation reaction, and the vacuum degree of the thermal insulation layer is ≤ 1 Pa; the first buffer tank and the second buffer tank are connected to a composition analysis system to realize the analysis of the gas composition in the buffer tanks; the thermal insulation layer is connected to an external vacuum pump to realize the evacuation of the thermal insulation layer; the thermal insulation layer is connected to an external inert gas cylinder to realize the filling of inert gas in the thermal insulation layer; an intake pipe is provided on the shell of the thermal insulation layer for connecting the filter and the raw material gas outside the thermal insulation layer, and an exhaust pipe is provided on the shell of the thermal insulation layer for discharging the product gas from the second buffer tank.

[0013] Optionally, an inert gas secondary containment is further provided outside the thermal insulation layer. The inert gas secondary containment is a closed cavity structure and is filled with inert gas during the disproportionation reaction; the inert gas secondary containment is connected to an external vacuum pump to realize the evacuation of the inert gas secondary containment; the inert gas secondary containment is connected to an external inert gas cylinder to realize the filling of inert gas in the inert gas secondary containment.

[0014] Optionally, an ionization chamber is further provided inside the thermal insulation layer for detecting tritium leakage; a hydrogen gas alarm and an ionization chamber are provided inside the inert gas secondary containment for monitoring hydrogen and tritium leakage.

[0015] Optionally, the leak rate of the inert gas secondary containment is lower than 10 -8 pa.m 3 / s, the inert gas in the inert gas secondary containment is helium or argon, and the inert gas secondary containment ≤ 0.05 MPa.

[0016] A low-temperature plasma disproportionation method mainly includes the following steps:

[0017] S10 Purify the raw material gas to remove impurities in the raw material gas and ensure that the impurities are lower than 10 ppm;

[0018] S20 Adjust the flow rate of the raw material gas through the mass flow controller;

[0019] S30 Conduct two-stage oxygen analysis to eliminate the risk of hydrogen explosion;

[0020] S40 Analyze the components of the raw material gas;

[0021] S50 Set the low-temperature plasma power supply to conduct the disproportionation reaction

[0022] After ensuring no hydrogen explosion or other safety hazards, start the disproportionation reaction by setting the voltage frequency duty cycle of the low-temperature plasma power supply; at the same time, turn on each ionization chamber and hydrogen gas alarm to monitor tritium leakage and hydrogen leakage in real time. If it exceeds the allowable value, stop the disproportionation reaction.

[0023] S60 Analyze the product gas components and evaluate the reaction efficiency. If the reaction efficiency does not meet the requirements, go to step S50 to adjust the parameters of the low-temperature plasma power supply to strive to achieve the set reaction efficiency.

[0024] S70 Output the product gas.

[0025] Optionally, in the disproportionation reaction method, if the oxygen content in the oxygen analyzer exceeds 100 ppm, or the hydrogen content in the secondary containment exceeds 1000 ppm, or the ionization chamber value exceeds 10 7 Bq / m 3 , cut off the power, close the valves at all levels and cut off the flow path to stop the disproportionation reaction.

[0026] The working principle or process of the low-temperature plasma disproportionation reaction unit: After the raw material gas enters the disproportionation reaction unit, under the action of the low-temperature plasma technology, in the reaction cavity of the straight pipe section of the U-shaped tube, due to the action of the externally applied alternating electric field, a certain electric field will be applied in the cavity. Through the action of the electric field, a small amount of free electrons in the hydrogen isotope atmosphere will be accelerated. The accelerated electrons will interact with gas molecules such as HT, DT, HD, H2, T2, D2, etc., and break their molecular bonds to form H + , D + and T + plasma and free electrons. The generated free electrons continue to be accelerated by the electric field in the reaction cavity and interact with the surrounding gas molecules. Through the above chain reaction, an electron avalanche will be formed, causing a large number of gas molecules to be ionized to form a low-temperature plasma state. In this state, the temperatures of gaseous molecules, ions and other substances are generally below 300 °C, and the generated electrons are usually in the range of (1 - 20 eV), with extremely high energy. In the above process, the hydrogen isotopes that are plasmaized into H + , D + and T + plasma, under the chemical reaction equilibrium, some ions will randomly combine into H2, D2 and T2, thus realizing the disproportionation of hydrogen isotopes. H2, D2 and T2 are discharged as product gas.

[0027] Advantages of the present invention: (1) Using plasma technology to replace the catalyst to complete the disproportionation reaction, without the need for precious metal catalysts, there is no catalyst shedding, no catalytic efficiency fluctuation, and extremely stable treatment efficiency can be provided; (2) Using plasma technology to replace the catalyst to complete the disproportionation reaction, without the need for precious metal catalysts, there is no subsequent treatment of tritium-containing waste, and the operating cost is low; (3) Using plasma technology to replace the catalyst to complete the disproportionation reaction, the reaction rate and conversion efficiency can be conveniently adjusted; (4) Using plasma technology to replace the catalyst to complete the disproportionation reaction, it can be applied to low-temperature environments and has extremely high efficiency. Because the raw material gas is mostly at a temperature of 77K or below, the catalytic activity of conventional catalysts is extremely low and they cannot efficiently process hydrogen isotopes, while the low-temperature plasma technology is not limited by temperature and still has extremely high efficiency at 77K. (5) Using plasma technology to replace the catalyst to complete the disproportionation reaction, there is no need for heating, and the operating cost is low. If a catalyst is used, the gas needs to be heated to 370K and then cooled down to a low temperature after the reaction, which will consume a large amount of energy, resulting in high operating costs and complex processes. Brief Description of the Drawings

[0028] Figure 1 It is a schematic structural diagram of a low-temperature plasma disproportionation reaction unit;

[0029] Figure 2 It is a schematic structural diagram of a low-temperature plasma disproportionation reactor;

[0030] Figure 3 It is the change of the gas atmosphere components before and after the start of low-temperature plasma at liquid nitrogen temperature;

[0031] In the figure: 1. Filter, 2. Mass flow controller, 3. First oxygen analyzer, 4. First buffer tank, 5. Second oxygen analyzer, 6. Low-temperature plasma disproportionation reaction unit, 7. Second buffer tank, 8. Thermal insulation layer, 9. Inert atmosphere secondary containment, 10. Vacuum pump, 11. Inert gas cylinder, 12. Composition analysis system, 13. Hydrogen gas alarm, 14. Ionization chamber;

[0032] 61. U-shaped tube, 62. First straight tube section, 63. Second straight tube section, 64. Inner electrode, 65. Outer electrode, 66. Seal, 67. Low-temperature plasma power supply, 68. Gas outlet, 69. Gas inlet;

[0033] 641. Metal electrode, 642. Alumina coating; 661. Ceramic piece, 662. Organic insulating medium;

[0034] 6411. Thick part, 6412. Fine part. Detailed Embodiments

[0035] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments and the accompanying drawings.

[0037] Figures 1 - 3 The low-temperature plasma disproportionation reaction unit, reactor and reaction effect of the present invention are shown.

[0038] Example 1

[0039] Figure 2 A low-temperature plasma disproportionation reactor is shown, which includes a filter 1, a mass flow controller 2, a first oxygen analyzer 3, a first buffer tank 4, a second oxygen analyzer 5, a low-temperature plasma disproportionation reaction unit 6, and a second buffer tank 7 that are sequentially connected and located within a heat insulation layer 8. Among them, the filter mainly purifies the raw material gas to ensure that various impurities in the raw material gas containing a hydrogen isotope atmosphere are less than 10 ppm, so as to avoid affecting the uniform discharge of the subsequent low-temperature plasma disproportionation reaction unit. The mass flow controller adjusts the flow rate of the raw material gas to regulate the amount of disproportionation reaction. The two-stage oxygen analysis of the first oxygen analyzer, buffer tank and the second oxygen analyzer 5 mainly monitors the oxygen content in the atmosphere in real time to avoid the oxygen in the raw material gas reaching the hydrogen explosion concentration under special circumstances and causing an explosion of the appropriate hydrogen isotope atmosphere in the low-temperature plasma reactor. The first buffer tank mainly plays the role of stabilizing the gas flow rate and buffering the oxygen concentration, reducing the rising speed of the oxygen concentration entering the low-temperature plasma under special circumstances. In order to accelerate the reaction rate or improve the low-temperature plasma disproportionation reaction unit 6, multiple units can be connected in parallel. The first buffer tank 4 and the second buffer tank 7 arranged before and after the low-temperature plasma disproportionation reaction unit 6 are connected to a composition analysis system 12. The composition analysis system 12 includes analysis instruments such as ionization chambers and chromatographs. It realizes the analysis of the gas composition and concentration in the buffer tank, as well as the comparison before and after the reaction, providing reference or data support for evaluating the disproportionation reaction efficiency. To reduce the interaction between tritium and metal, the low-temperature plasma disproportionation reaction unit 6 will adopt a double dielectric barrier discharge structure. The inner electrode 64 selects a metal electrode 641 with an alumina coating 642 on its surface, such as copper. The dielectric layer selects alumina ceramic materials or a high-purity quartz structure with an alumina coating on its inner surface and other inorganic insulating materials with high strength. The outer electrode 65 will adopt a metal material with good electrical conductivity such as copper. The specific structure is shown in Figure 1 , and the specific details can be seen in Example 2.

[0040] For the disproportionation reactor, the feed gas comes from separation systems such as cryogenic distillation or chromatography for hydrogen isotopes. Since the operating temperatures of cryogenic distillation and chromatography systems need to be between 20K and 77K, the temperatures of the feed gas and product gas must also be maintained at this temperature. Based on this, to maintain the temperature of the atmosphere and reduce the energy efficiency required for subsequent refrigeration of the product gas, a heat-insulating layer 8 is designed for the disproportionation reactor to ensure the loss of cold during the reaction process. The inlet pipe connecting the filter to the external feed gas and the exhaust pipe after the reaction both pass through the heat-insulating layer 8, and the pipe and the heat-insulating layer must be sealed to ensure the vacuum degree of the heat-insulating layer. In addition, at low temperatures, hydrogen isotopes (HT, HD, and DT) have higher conversion rates, so the system also needs to maintain the atmosphere at the lowest possible temperature. For the heat-insulating layer, a sealed cavity structure should be adopted. This cavity can be connected to an external vacuum pump so that the vacuum degree inside the cavity is less than 1 Pa to minimize the loss of cold from the atmosphere. The heat-insulating layer 8 can also be connected to an inert gas cylinder 11 at the same time to handle possible special situations and replace the gas. An ionization chamber is also provided inside the heat-insulating layer 8 to detect whether there is a leak of tritium gas.

[0041] Since tritium is radioactive, an inert atmosphere secondary containment 9 is designed outside the heat-insulating layer 8 to ensure safety. The inert atmosphere secondary containment 9 is a sealed cavity structure. The inert atmosphere secondary containment is filled with inert gas during the disproportionation reaction; the inert atmosphere secondary containment is connected to an external vacuum pump to evacuate the inert atmosphere secondary containment; the inert atmosphere secondary containment is connected to an external inert gas cylinder to fill the inert gas inside the inert atmosphere secondary containment. When the inert atmosphere secondary containment 9 is designed, the inlet pipe of the feed gas and the outlet pipe of the product gas also pass through the inert atmosphere secondary containment 9, and like the heat-insulating layer 8, the pipe and the inert atmosphere secondary containment 9 need to be sealed well to ensure that the leakage rate of the internal inert gas meets the requirements. The leakage rate of the secondary containment should be lower than 10 -8 pa·m 3 / s, filled with helium or argon as a protective atmosphere inside, the pressure inside the secondary containment is about -0.05 MPa (negative pressure), and an ionization chamber 14 and a hydrogen gas alarm 13 are installed inside to ensure the safety of the system. During operation, if the oxygen content in the oxygen analyzer exceeds 100 ppm, or the hydrogen content inside the secondary containment exceeds 1000 ppm, or the ionization chamber value exceeds 10 7 Bq / m 3 , the disproportionation reactor will automatically cut off the power, close all valves, and cut off the flow path to ensure safety.

[0042] Example 2

[0043] During the process of low-temperature plasma-enhanced hydrogen isotope disproportionation reaction, the low-temperature plasma disproportionation reaction unit is the most core part and the place where the disproportionation reaction takes place. Therefore, the structure of the low-temperature plasma disproportionation reaction unit adapted to the low-temperature environment will be comprehensively designed. The specific structure is as Figure 1 shown. The reaction unit has a U-shaped tube structure, and the discharge method adopts a double dielectric barrier discharge structure, and the discharge method is rod-tube type discharge.

[0044] The low-temperature plasma disproportionation reaction unit 6 includes a U-shaped tube 61, and the U-shaped tube 61 is made of high-strength ceramic or high-strength quartz glass; a columnar inner electrode 64 is coaxially arranged in both the first straight tube section 62 and the second straight tube section 63 of the U-shaped tube 61. The inner electrode 64 includes a columnar metal electrode 641 and an alumina coating 642 coated on the surface of the metal electrode 641. The alumina coating 642 is a tritium barrier coating, which can prevent tritium from interacting with the metal and finally entering the metal and penetrating outside the reactor, causing pollution. For safety reasons, an alumina tritium barrier coating should also be provided on the inner surface of the U-shaped tube 61. An outer electrode 65 is coaxially arranged at a position corresponding to the columnar inner electrode 64 outside the first straight tube section 62 and outside the second straight tube section 63, and the outer electrode 65 should be well grounded. The outer electrode 65 can be a metal mesh, such as a stainless steel mesh, or a metal foil, etc. To prevent tritium in the U-shaped tube from leaking from the top of the U-shaped tube, seals 66 are provided at the ends of the first straight tube section 62 and the second straight tube section 63. The seal 66 is a seal combined with double ceramic sheets 661 and an organic insulating medium 662. The ceramic sheets 661 are respectively located above and below the organic insulating medium 662. The ceramic sheets mainly play a role in blocking the penetration of hydrogen isotopes, and the organic insulating medium plays a role in sealing, heat insulation, providing insulation and fixing the inner electrode. The upper part of the inner electrode passes through the seal 66 and is connected to an external low-temperature plasma power supply. An air inlet 69 is provided in the first straight tube section 62 for injecting the raw material gas, and an air outlet 68 is provided in the second straight tube section 63 for discharging the reacted atmosphere.

[0045] The metal electrode 641 in the inner electrode 64 is a columnar copper electrode that is thinner at the top and thicker at the bottom. The outer electrode 65 is a cylindrical stainless steel mesh. The thick part 6411 of the copper electrode corresponds to the outer electrode 65, and the top of the thick part 6411 is lower than the air inlet and the air outlet. With such a setting, the gap of the thick part is small, and it is easy to achieve discharge. It can control the discharge area to be concentrated in the lower thick area, and the discharge position can also be adjusted by adjusting the positions of the thick part 6411 and the outer electrode 65.

[0046] Among them, by adjusting the output voltage, frequency, center frequency, duty cycle, etc. of the low-temperature plasma power supply, the discharge performance in the low-temperature plasma reactor can be regulated, thereby regulating the reaction efficiency of the hydrogen isotope disproportionation reaction. The low-temperature plasma power supply needs to select DC high-frequency, AC high-frequency, modulated pulse, and pulse power supplies, and the output voltage needs to be greater than 6 kV. In addition to increasing the power of the low-temperature plasma power supply, multiple reaction units can be connected in parallel to multiply the processing capacity to improve the ability to process gases.

[0047] Example 3

[0048] Use the disproportionation reactor in Example 1 to carry out the disproportionation reaction. The main steps are as follows:

[0049] S10 Remove the impurities in the feed gas from the low-temperature rectification and hydrogen isotope separation system through Filter 1 to purify the feed gas and avoid impurities affecting the discharge of the subsequent low-temperature plasma reactor. The main components in the feed gas are hydrogen isotope gases;

[0050] S20 After purification, adjust the flow rate of the feed gas through the mass flow controller;

[0051] S30 Pass through the first oxygen analyzer 3, the first buffer tank 4, and the second oxygen analyzer 5 in sequence to complete two-stage oxygen analysis and monitor the oxygen content in the atmosphere in real time, avoiding explosion of the hydrogen isotope atmosphere in the low-temperature plasma reactor when oxygen enters the feed gas under special circumstances and reaches the hydrogen explosion concentration;

[0052] S40 Use the component analysis system 12 to analyze the components and concentrations of each component of the feed gas in the first buffer tank 4. The component analysis system 12 mainly includes analysis instruments such as ionization chambers and chromatographs;

[0053] S50 Set the low-temperature plasma power supply and inject the feed gas into the low-temperature plasma disproportionation reaction unit for disproportionation reaction;

[0054] After ensuring no hydrogen explosion or other safety hazards, start the disproportionation reaction by setting the voltage frequency duty cycle of the low-temperature plasma power supply; at the same time, turn on each ionization chamber and hydrogen gas alarm to monitor tritium leakage and hydrogen leakage in real time. If it exceeds the allowable value, stop the disproportionation reaction.

[0055] S60 Inject the product gas after the disproportionation reaction into the second buffer tank 7, use the component analysis system 12 to analyze the components and concentrations of each component of the feed gas in the second buffer tank 7, compare with the first buffer tank 4, evaluate the reaction efficiency. If the reaction efficiency does not meet the requirements, turn to step S50 to adjust the parameters of the low-temperature plasma power supply to strive to achieve the set reaction efficiency;

[0056] S70 Discharge the product gas.

[0057] In the disproportionation reaction method, if the oxygen content in the oxygen analyzer exceeds 100 ppm, or the hydrogen content in the secondary containment exceeds 1000 ppm, or the ionization chamber value exceeds 107 Bq / m3, power is cut off, valves at all levels are closed, and the flow path is cut off to stop the disproportionation reaction.

[0058] Before the whole reaction or before introducing the feed gas, 99.99% pure hydrogen can be introduced to exhaust the whole disproportionation reactor, or the feed gas purified to a concentration lower than the hydrogen explosion concentration can be directly used to exhaust the disproportionation reactor.

[0059] Figure 3 The disproportionation reaction effect of Example 3 is shown. Among them, the discharge length in the reaction unit is about 10 cm, the discharge mode of modulated pulse is adopted, the voltage in the reaction chamber is about 6 kV, and the input power is 30 watts. From Figure 3 It can be seen that the disproportionation reaction between hydrogen and deuterium is realized at the liquid nitrogen temperature, verifying the feasibility of the technology. In the above examples, the plasma technology is used to replace the catalyst to complete the disproportionation reaction. There is no need for precious metal catalysts, there is no catalyst shedding, the catalytic efficiency is stable, the stability of the disproportionation reaction can be ensured for a long time, and there is no problem of treating waste catalysts containing tritium. The operating cost is low. By setting up a low-temperature plasma, the plasma technology is used to replace the catalyst to complete the disproportionation reaction, which can conveniently adjust the reaction rate and conversion efficiency. At the same time, using the plasma technology to replace the catalyst to complete the disproportionation reaction can be applied to low-temperature environments and has extremely high efficiency. Because the feed gas is mostly at a temperature of 77 K or below, the catalytic activity of conventional catalysts is extremely low, and they cannot efficiently process hydrogen isotopes. However, the low-temperature plasma technology is not limited by temperature and still has extremely high efficiency at 77 K. Without a catalyst, there is no need to first heat up to 370 K and then cool down to a low temperature, avoiding problems such as high energy consumption, high operating cost, and complex process in the traditional precious metal catalyst process.

Claims

1. A low-temperature plasma disproportionation reaction unit, characterized in that The low-temperature plasma disproportionation reaction unit includes a U-shaped tube made of high-strength ceramic or high-strength quartz glass. Columnar inner electrodes are coaxially arranged inside the first straight tube section and the second straight tube section of the U-shaped tube. The inner electrode includes a columnar metal electrode and an alumina coating covering the surface of the metal electrode. Outer electrodes are coaxially arranged at positions corresponding to the columnar inner electrodes outside the first straight tube section and the second straight tube section, and the outer electrodes are grounded. Seals are provided at the ends of the first straight tube section and the second straight tube section. Part of the upper end of the inner electrode is encapsulated in the seal, and the upper end of the inner electrode is connected to an external low-temperature plasma power supply. An air inlet is provided on the first straight tube section, and an air outlet is provided on the second straight tube section.

2. The low-temperature plasma disproportionation reaction unit according to claim 1, wherein, The seal is a seal combined by double ceramic sheets and an organic insulating medium, and the double ceramic sheets are respectively located at the upper and lower parts of the organic insulating medium.

3. The low-temperature plasma disproportionation reaction unit according to claim 1, wherein The metal electrode is a columnar electrode with a thinner upper part and a thicker lower part. The outer electrode is a cylindrical stainless steel mesh. The thick part of the metal electrode corresponds to the outer electrode, and the top of the thick part is lower than the air inlet and the air outlet.

4. The low-temperature plasma disproportionation reaction unit according to claim 1, characterized in that The output voltage, frequency, center frequency, and duty cycle of the low-temperature plasma power supply are adjustable.

5. A low-temperature plasma disproportionation reactor based on the low-temperature plasma disproportionation reaction unit according to any one of claims 1 to 4, comprising a filter, a mass flow controller, a first oxygen analyzer, a first buffer tank, a second oxygen analyzer, a low-temperature plasma disproportionation reaction unit, and a second buffer tank that are sequentially connected in series and located inside a heat preservation layer. The low-temperature plasma disproportionation reaction unit is one or more in parallel. The heat preservation layer is a closed cavity structure and is in a vacuum state during the disproportionation reaction, and the vacuum degree of the heat preservation layer ≤ 1 Pa. The first buffer tank and the second buffer tank are connected to a component analysis system to analyze the gas components in the buffer tanks. The heat preservation layer is connected to an external vacuum pump to evacuate the heat preservation layer. The heat preservation layer is connected to an external inert gas cylinder to fill the heat preservation layer with inert gas. An intake pipeline is provided on the shell of the heat preservation layer for connecting the filter and the raw material gas outside the heat preservation layer, and an exhaust pipeline is provided on the shell of the heat preservation layer for discharging the product gas from the second buffer tank.

6. The low-temperature plasma disproportionation reactor according to claim 5, characterized in that, An inert atmosphere secondary containment is further provided outside the heat preservation layer. The inert atmosphere secondary containment is a closed cavity structure and is filled with inert gas during the disproportionation reaction. The inert atmosphere secondary containment is connected to an external vacuum pump to evacuate the inert atmosphere secondary containment. The inert atmosphere secondary containment is connected to an external inert gas cylinder to fill the inert gas inside the inert atmosphere secondary containment.

7. The low-temperature plasma disproportionation reactor according to claim 6, characterized in that, An ionization chamber is further provided inside the heat preservation layer for detecting tritium leakage. A hydrogen gas alarm and an ionization chamber are provided inside the inert atmosphere secondary containment for monitoring hydrogen and tritium leakage.

8. The low-temperature plasma disproportionation reactor according to claim 7, characterized in that, The leakage rate of the secondary containment in an inert atmosphere is less than 10 -8 Pa·m 3 / s. The inert gas in the secondary containment of the inert atmosphere is helium or argon, and the pressure of the secondary containment of the inert atmosphere is ≤ 0.05 MPa.

9. A low-temperature plasma disproportionation reaction method based on the low-temperature plasma disproportionation reactor described in claim 7 or 8, characterized in that, The method mainly includes the following steps: S10 Purify the raw material gas to remove impurities in the raw material gas and ensure that the impurities are less than 10 ppm. S20 Adjust the flow rate of the raw material gas through the mass flow controller. S30 Conduct two-stage oxygen analysis to eliminate the risk of hydrogen explosion. S40 Analyze the components of the raw material gas. Set the low-temperature plasma power supply for disproportionation reaction; After ensuring no hydrogen explosion or other safety hazards, start the disproportionation reaction by setting the voltage frequency duty cycle of the low-temperature plasma power supply; at the same time, turn on each ionization chamber and hydrogen gas alarm to monitor tritium leakage and hydrogen gas leakage in real time. If it exceeds the allowable value, stop the disproportionation reaction; S60 Analyze the product gas components and evaluate the reaction efficiency. If the reaction efficiency does not meet the requirements, go to step S50 to adjust the parameters of the low-temperature plasma power supply to strive to achieve the set reaction efficiency; S70 Output the product gas.

10. The method for low-temperature plasma disproportionation reaction according to claim 9, characterized in that, In the disproportionation reaction method, if the oxygen content in the oxygen analyzer exceeds 100 ppm, or the hydrogen content in the secondary containment exceeds 1000 ppm, or the ionization chamber value exceeds 10 7 Bq / m 3 , power off, close all levels of valves and cut off the flow path to stop the disproportionation reaction.

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