High throughput low temperature plasma reactor and method of decomposing hydrogen sulfide

Abstract

The application relates to the field of plasma chemistry, and discloses a high-flux low-temperature plasma reactor and a method for decomposing hydrogen sulfide, which comprises the following steps: an inner cylinder (1) containing at least two parallel reaction tubes (14); an outer cylinder (2) nested outside the inner cylinder (1); a central high-voltage electrode (3) arranged in each reaction tube (14) respectively; a grounding electrode (4) formed by solid conductive material; and a blocking medium forming at least part of the side wall of the reaction tube or being arranged around the inner side wall of each reaction tube (14). The aforementioned high-flux low-temperature plasma reactor can be used for plasma decomposition of hydrogen sulfide, and the reactor can generate uniform and efficient dielectric barrier discharge, so that hydrogen sulfide is directly decomposed into hydrogen and sulfur.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of plasma chemistry, in particular to a high-throughput low-temperature plasma reactor and a method for decomposing hydrogen sulfide. BACKGROUND

[0002] Hydrogen sulfide (H2S) is a toxic, foul-smelling, acidic gas, which not only causes corrosion of materials such as metals, but also harms human health and pollutes the environment. At present, traditional Claus method is used in large and medium-sized oil refineries in China to treat tail gas containing H2S and recover sulfur. This method only recovers sulfur in hydrogen sulfide, but converts valuable hydrogen into water. From the perspective of comprehensive utilization of resources, hydrogen resources have not been effectively utilized in the traditional hydrogen sulfide recovery process. Therefore, the decomposition of hydrogen sulfide into sulfur and hydrogen has gradually become the focus of attention in the technical field of domestic and foreign researchers.

[0003] At present, the methods for decomposing hydrogen sulfide mainly include high-temperature decomposition, electrochemical method, photocatalytic method and low-temperature plasma method. Among the foregoing methods, the high-temperature thermal decomposition method is relatively mature in industrial technology, but the thermal decomposition of hydrogen sulfide is strongly dependent on the reaction temperature and is limited by the thermodynamic equilibrium. Even if the reaction temperature is above 1000℃, the conversion rate of hydrogen sulfide is only 20%. In addition, the high-temperature condition has high requirements for the material of the reactor, which also increases the operating cost. In addition, due to the low conversion rate of hydrogen sulfide thermal decomposition, a large amount of hydrogen sulfide gas needs to be separated from the tail gas and recycled in the system, thus reducing the efficiency of the device and increasing the energy consumption, which all bring difficulties to its large-scale industrial application. Although the use of membrane technology can effectively separate the products and thus break the balance limit to improve the conversion rate of hydrogen sulfide, the thermal decomposition temperature often exceeds the limit of the heat resistance of the membrane, causing the structure of the membrane material to be damaged. The electrochemical method has the disadvantages of multiple operation steps, serious equipment corrosion, poor reaction stability and low efficiency. The photocatalytic method for decomposing hydrogen sulfide mainly draws on the research of photocatalytic decomposition of water, and the research focuses on the development of high-efficiency semiconductor photocatalysts. The use of solar energy to decompose hydrogen sulfide has the advantages of low energy consumption, mild reaction conditions and simple operation, and is a relatively economical method. However, this method has the problems of small processing capacity, low catalytic efficiency and easy deactivation of the catalyst.

[0004] Compared with other decomposition methods, the low-temperature plasma method has the advantages of simple operation, small device volume, high energy efficiency, and highly controllable reactions. It can be flexibly applied in small processing capacity and difficult centralized processing situations. In addition, due to its high energy density and short reaction time, it can effectively decompose hydrogen sulfide at low temperatures, suitable for different scales, layout dispersion, and variable production conditions. Moreover, while recovering sulfur, the low-temperature plasma method recovers hydrogen resources, enabling the resource utilization of hydrogen sulfide.

[0005] Currently, researchers at home and abroad have conducted extensive research on the low-temperature plasma decomposition of hydrogen sulfide technology. The main discharge forms used include glow discharge, corona discharge, sliding arc discharge, microwave plasma, radio frequency plasma, and dielectric barrier discharge.

[0006] The literature "International journal of hydrogen energy", 2012, 37: 1335-1347. adopts the method of shrinking normal glow discharge to decompose hydrogen sulfide, and obtains the lowest decomposition energy consumption of hydrogen sulfide as 2.35 eV / H2S under the conditions of pressure 0.02 Mpa and temperature 2000-4000 K. However, this reaction has high temperature and low pressure, which is harsh and difficult to achieve.

[0007] The literature "International journal of hydrogen energy", 2012, 37: 10010-10019 adopts microwave plasma to decompose hydrogen sulfide, which can completely decompose hydrogen sulfide at atmospheric pressure and a temperature of 2400 K. However, the decomposed hydrogen and sulfur will rapidly recombine to form hydrogen sulfide at high temperatures, and there is currently no corresponding quenching measure.

[0008] The paper "Chemical Engineering Science", 2009, 64 (23): 4826-4834. The decomposition of H2S to produce hydrogen and sulfur by pulse corona discharge was studied. The reactor used a wire tube structure, and the effects of pulse forming capacitor, discharge voltage and pulse frequency on H2S conversion rate and decomposition energy efficiency were investigated under the condition of fixed power 100 W. The results showed that under the condition of constant power, low pulse forming capacitor, low discharge voltage and high pulse frequency were conducive to obtain high H2S decomposition energy efficiency; in addition, compared with Ar and N2 as the balance gas, higher H2S conversion rate could be obtained when Ar-N2 mixed gas was used as the balance gas. When the volume fraction of Ar / N2 / H2S was 46% / 46% / 8%, the discharge power was 60 W, and the pulse forming capacitor was 720 pF, the lowest decomposition energy consumption of H2S was 4.9 eV / H2S, but the H2S conversion rate was only about 30%. In addition, the flow rate of this reaction system was only 1.18 x 10 -4 SCMs -1 This low flow, low concentration, low conversion reaction effect has no practical significance in industrial production.

[0009] The paper "Journal of applied physics", 1998, 84 (3): 1215-1221 used sliding arc discharge to study the decomposition of H2S. The method is to dilute H2S with air to a concentration of 0-100 ppm, and the effects of gas flow rate, reaction chamber size and frequency on H2S decomposition reaction were investigated under the condition of total gas flow rate of 0-100 L / min. The experimental results showed that low gas flow rate, small disc spacing and low frequency were conducive to obtain higher H2S conversion rate. Under the optimized discharge conditions, the H2S conversion rate could reach 75-80%, but the H2S decomposition energy consumption was as high as 500 eV / H2S. This low concentration and high energy consumption reaction effect also has no industrial application prospect.

[0010] Dielectric barrier discharge can usually be generated at atmospheric pressure, and the discharge temperature is low. In addition, the growth of discharge current is limited by the presence of dielectric, which avoids the formation of spark or arc due to complete breakdown of gas, which is conducive to the generation of large volume, stable plasma, and has good industrial application prospect.

[0011] The literature "Plasma chemistry and plasma processing", 1992, 12(3):275-285 investigated the discharge characteristics of H2S in the range of 130-560℃ using a modified ozone generator, and studied the effects of reaction temperature, H2S feed concentration, injection power and the addition of H2, Ar, N2, etc. on the conversion of H2S and energy efficiency. It was found that the addition of Ar could promote the decomposition of H2S, and under the conditions of total flow rate of 50-100 mL / min and H2S concentration of 20-100%, the conversion rate was 0.5-12%, and the minimum energy consumption for hydrogen production was about 0.75 mol / kWh (50 eV / H2). However, this process still has the disadvantages of low conversion rate and high energy consumption.

[0012] CN102408095A uses medium barrier discharge and photocatalyst to cooperatively decompose hydrogen sulfide, which is to fill the solid catalyst with photocatalytic activity in the plasma zone. However, this method has the disadvantage that the sulfur produced by the decomposition of hydrogen sulfide will deposit below the catalyst bed.

[0013] The literature "International Journal of Energy Research", 2013, 37(11):1280-1286. Al2O3, MoO x / Al2O3, CoOx / Al2O3 and NiO / Al2O3 catalysts were filled in the discharge zone, and the decomposition of H2S was studied using medium barrier discharge and catalyst. The reaction results showed that MoOx / Al2O3 and CoOx / Al2O3 catalysts had good effect; among them, when MoOx / Al2O3 catalyst was filled, the highest conversion rate of H2S was about 48% under the conditions of H2S / Ar total flow rate of 150 mL / min, H2S concentration of 5 vol%, injection specific energy SIE of 0.92 kJ / L, and catalyst filling length of 10% of the bed. However, this reaction process has the disadvantages of low hydrogen sulfide concentration, sulfur produced by decomposition deposited in the reactor, and with the extension of time, the activity of the catalyst decreases, the stability of the discharge decreases, leading to the gradual decrease of the conversion rate of hydrogen sulfide.

[0014] CN103204466A discloses a temperature-controlled hydrogen sulfide decomposition device and method, the device is characterized in that the center electrode is metal, and the grounding electrode is a temperature-controllable circulating liquid. The hydrogen sulfide decomposition process can be continuously and stably carried out by controlling the temperature of the liquid grounding electrode. In addition, CN103204467A discloses a device and method for continuously and stably decomposing hydrogen sulfide to produce hydrogen. The prior art is characterized in that the center electrode is metal, and the grounding electrode is a temperature-controllable circulating liquid. The temperature of the liquid grounding electrode is controlled, the raw material gas inlet direction is circumferential, and the generated sulfur is separated out in a spiral mode along the axial direction. However, in order to ensure that the hydrogen sulfide is decomposed as much as possible, the flow rate of the hydrogen sulfide needs to be controlled to make the residence time of the hydrogen sulfide in the reactor inner cylinder longer, and the size of the inner cylinder needs to be controlled to make the unit volume of gas in the inner cylinder obtain more electric energy. Since the current prior art cannot provide a power supply with higher power, even if the residence time of the hydrogen sulfide is controlled to be longer and the size of the inner cylinder is controlled to make the unit volume of gas in the inner cylinder obtain more electric energy, the highest conversion rate of the hydrogen sulfide can only reach about 20% using the method disclosed in CN103204466A and CN103204467A. When the highest conversion rate of the hydrogen sulfide reaches about 20%, the energy consumption of the hydrogen sulfide decomposition reaction is relatively high, and is not suitable for large-scale industrial applications. Further, the method disclosed in CN103204466A and CN103204467A also has the defect that the types of liquid grounding electrodes available are very few. The salt solution disclosed therein can only maintain the temperature of the reactor below 100°C. Below 100°C, elemental sulfur is generally in a solid state, which can easily cause the reactor to be blocked. SUMMARY

[0015] One of the purposes of the present application is to overcome the defects of the low-temperature plasma reactor provided by the prior art, i.e., uneven discharge and inability to achieve a high hydrogen sulfide decomposition conversion rate under high power conditions. The present application provides a new high-flux low-temperature plasma reactor and a method for decomposing hydrogen sulfide using the reactor.

[0016] The second purpose of the present application is to provide a high-flux low-temperature plasma reactor with a high hydrogen sulfide decomposition conversion rate and low decomposition energy consumption.

[0017] To achieve the above-mentioned purposes, in a first aspect, the present application provides a high-flux low-temperature plasma reactor having a jacketed cylinder structure, and the reactor comprises:

[0018] an inner cylinder, the inner cylinder being provided with a reactor inlet and a product outlet respectively, and the inner cylinder containing at least two reaction tubes arranged in parallel, the top and bottom of each of the reaction tubes being respectively corresponding to each other, so that the raw material introduced from the reactor inlet can enter into each of the reaction tubes, and the product generated in each of the reaction tubes can be led out by the product outlet;

[0019] an outer cylinder, the outer cylinder being nested outside the inner cylinder, and the outer cylinder being provided with a heat conducting medium inlet and a heat conducting medium outlet respectively, the heat conducting medium introduced from the heat conducting medium inlet can be distributed between each of the reaction tubes of the inner cylinder, and the heat conducting medium is led out by the heat conducting medium outlet;

[0020] a center high voltage electrode, the center high voltage electrode being arranged in each of the reaction tubes of the inner cylinder respectively;

[0021] a grounding electrode, the material forming the grounding electrode being solid conductive material, and the grounding electrode forming at least part of the side wall of each of the reaction tubes or the grounding electrode being arranged around the outer side wall of each of the reaction tubes respectively;

[0022] a barrier medium, the barrier medium forming at least part of the side wall of each of the reaction tubes so that at least part of the barrier medium surrounds the center high voltage electrode, or the barrier medium being arranged around the inner side wall of each of the reaction tubes;

[0023] in each of the reaction tubes, the barrier medium is arranged so that the discharge region between the center high voltage electrode and the grounding electrode is spaced by the barrier medium,

[0024] in each of the reaction tubes, the distance L1 between the outer side wall of the center high voltage electrode and the inner side wall of the barrier medium and the thickness D1 of the barrier medium have a proportional relationship of L1:D1=(0.05-100):1.

[0025] In a second aspect, the present application provides a method for decomposing hydrogen sulfide, the method being implemented in the high flux low temperature plasma reactor of the first aspect of the present application, the method comprising: introducing raw gas containing hydrogen sulfide from the reactor inlet into each of the reaction tubes of the inner cylinder of the high flux low temperature plasma reactor for hydrogen sulfide decomposition reaction under dielectric barrier discharge condition, and the obtained stream after decomposition is led out by the product outlet, and the temperature required by the high flux low temperature plasma reactor is maintained by continuously introducing heat conducting medium into the outer cylinder of the high flux low temperature plasma reactor from the heat conducting medium inlet and leading out the heat conducting medium from the heat conducting medium outlet, and the dielectric barrier discharge is formed by the grounding electrode, the barrier medium and the center high voltage electrode.

[0026] The aforementioned high-throughput low-temperature plasma reactor provided by the present invention can be used for the plasma decomposition of hydrogen sulfide. The reactor can generate uniform and efficient dielectric barrier discharge, thereby directly decomposing hydrogen sulfide into hydrogen and sulfur.

[0027] The aforementioned high-throughput low-temperature plasma reactor of the present invention can achieve high-conversion decomposition of hydrogen sulfide under high-throughput conditions, and the decomposition energy consumption is low. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a preferred embodiment of the high-throughput low-temperature plasma reactor provided by the present invention.

[0029] Explanation of reference numerals in the attached figures

[0030] 1. Inner cylinder 2. Outer cylinder

[0031] 11. Reactor inlet; 21. Heat transfer medium inlet

[0032] 12. Gas product outlet; 22. Heat transfer medium outlet

[0033] 13. Liquid product export

[0034] 14. Reaction tube

[0035] 3. Central high-voltage electrode

[0036] 4. Grounding electrode

[0037] 5. Grounding wire Detailed Implementation

[0038] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0039] As previously described, the present invention provides a high-throughput low-temperature plasma reactor, which has a jacketed structure and comprises:

[0040] The inner cylinder is provided with a reactor inlet and a product outlet, and contains at least two reaction tubes arranged in parallel, with the top and bottom of each reaction tube respectively connected, so that the raw material entering from the reactor inlet can enter each of the reaction tubes respectively, and the product generated in each of the reaction tubes can be led out from the product outlet.

[0041] An outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively arranged on the outer cylinder, the heat-conducting medium introduced through the heat-conducting medium inlet can be distributed among the reaction tubes of the inner cylinder, and the heat-conducting medium is led out through the heat-conducting medium outlet;

[0042] A central high-voltage electrode is respectively arranged in each reaction tube of the inner cylinder;

[0043] A grounding electrode is formed of a solid conductive material, and forms at least part of the side wall of each reaction tube or is respectively arranged around the outer side wall of each reaction tube;

[0044] A barrier medium forms at least part of the side wall of each reaction tube so that at least part of the barrier medium surrounds the central high-voltage electrode, or the barrier medium is respectively arranged around the inner side wall of each reaction tube;

[0045] In each reaction tube, the barrier medium is arranged so that the discharge region between the central high-voltage electrode and the grounding electrode is separated by the barrier medium,

[0046] In each reaction tube, the distance L1 between the outer side wall of the central high-voltage electrode and the inner side wall of the barrier medium and the thickness D1 of the barrier medium have a proportional relationship of L1:D1=(0.05-100):1.

[0047] The difference between the "side wall", "outer side wall" and "inner side wall" in the present application is that the "outer side wall" and "inner side wall" respectively represent the outer surface and the inner surface of the "side wall".

[0048] In the present application, the top and the bottom respectively correspond to the structure formed by the respective reaction tubes in communication, which is referred to as an inner cylinder.

[0049] In each reaction tube of the present application, a central high-voltage electrode is respectively arranged, preferably the central high-voltage electrode is arranged at the axial core position of each reaction tube, thereby facilitating uniform discharge of the reactor of the present application. The central high-voltage electrode in each reaction tube arranged at the axial core position can be respectively connected with a power supply; the central high-voltage electrode in each reaction tube arranged at the axial core position can also be connected in parallel in the inner cylinder of the reactor, and then the parallelly connected central high-voltage electrodes are connected with the power supply.

[0050] According to a preferred specific embodiment, the barrier medium forms at least part of the side wall of each reaction tube so that at least part of the barrier medium surrounds the central high-voltage electrode, and the grounding electrode is respectively arranged around the outer side wall of each reaction tube.

[0051] More preferably, the side wall of each of the reaction tubes is formed entirely by the barrier medium.

[0052] In the present application, two specific cases are provided for the arrangement of the barrier medium, the first case being that the barrier medium forms at least part of the side wall of each of the reaction tubes so that at least part of the barrier medium surrounds the central high-voltage electrode, and when the arrangement of the barrier medium is the first case, the grounding electrode is arranged on the outer side wall of the reaction tube; the second case being that the barrier medium surrounds the inner side wall of each of the reaction tubes, and the grounding electrode forms at least part of the side wall of each of the reaction tubes.

[0053] The jacketed sleeve structure design of the present application can make the heat-conducting medium circulate in the shell layer, maintain the entire reactor within a certain temperature range while ensuring the discharge intensity, make the generated sulfur flow out of the reactor in liquid form, and effectively avoid the solidification of the sulfur generated by the decomposition of hydrogen sulfide, so that the decomposition process can be continuously and stably realized for long-period operation while achieving a high conversion rate.

[0054] Preferably, in each of the reaction tubes, the distance L1 between the outer side wall of the central high-voltage electrode and the inner side wall of the barrier medium and the thickness D1 of the barrier medium have a proportional relationship of L1:D1=(0.1-30):1. The inventors of the present application have found in research that, by controlling the relationship between L1 and D1 within the aforementioned range of the present application, and particularly within the aforementioned preferred range, the reactor of the present application can more obviously improve the conversion rate of hydrogen sulfide and reduce the decomposition energy consumption relative to the prior art.

[0055] According to one preferred specific embodiment, the central high-voltage electrodes in each of the reaction tubes are connected in parallel to each other.

[0056] Preferably, the material forming the barrier medium is an electrically insulating material, and more preferably the material forming the barrier medium is selected from at least one of glass, ceramic, enamel, polytetrafluoroethylene, mica, and high-voltage electrically insulating metal. The glass can be quartz glass or hard glass; the material forming the barrier medium can also be other high-voltage electrically insulating metals and non-metallic composite materials, etc. The ceramic can be alumina ceramic.

[0057] Preferably, the reactor further comprises a grounding wire, the grounding wire being arranged on the outer side wall of the outer cylinder and connected at one end to the grounding electrode in each of the reaction tubes.

[0058] Preferably, the reactor inlet is arranged at the upper part of the inner cylinder, and the product outlet is arranged at the lower part and / or the bottom of the inner cylinder.

[0059] According to a preferred embodiment, the product outlet comprises a gas product outlet and a liquid product outlet, and the gas product outlet is arranged at the lower part of the inner cylinder, and the liquid product outlet is arranged at the bottom of the inner cylinder.

[0060] According to a preferred embodiment, each of the reaction tubes has the same size. The same size means that each of the reaction tubes has the same size and shape. The arrangement of the reaction tubes of the present application is not particularly limited, and the arrangement cross section can be an equilateral triangle, an equilateral hexagon, a circle, etc.

[0061] In the present application, in each of the reaction tubes, the ratio of the inner diameter of the reaction tube to the aperture of the product outlet can be (0.1-100):1.

[0062] In the present application, the ratio of the aperture of the reactor inlet to the aperture of the product outlet can be (0.1-120):1.

[0063] In each of the reaction tubes, the ratio between the length of the reaction tube of the present application and the inner diameter of the reaction tube can be (0.5-500):1.

[0064] Preferably, the gas product outlet is arranged below all of the discharge regions, and the ratio between the height H1 of the arrangement position of the gas product outlet relative to the bottom of the inner cylinder and the length L2 of the discharge region is H1:L2=1:(0.05-25000); preferably H1:L2=1:(0.1-10000); more preferably H1:L2=1:(0.5-1000).

[0065] Preferably, the heat-conducting medium inlet and the heat-conducting medium outlet are arranged at the lower part and the upper part of the outer cylinder, respectively.

[0066] The reactor inlet of the present application can be arranged such that the raw material gas entering the inner cylinder is parallel or at a certain angle to the inner diameter of the inner cylinder, for example, can be tangentially arranged.

[0067] The inner diameter of the present application means the diameter.

[0068] Preferably, the material forming the grounding electrode is selected from graphite tube, metal tube, metal foil or metal mesh. The solid grounding electrode of the present application can generate a larger micro-discharge current under the condition of a certain injection power, which is more conducive to the bond-breaking decomposition reaction of hydrogen sulfide. The metal tube and metal foil in the material forming the grounding electrode can include elemental metal tube, elemental metal foil, alloy metal tube, alloy metal foil. The inventors of the present application have found that when the solid conductive material is arranged around the outer sidewall of the reaction tube or forms at least part of the sidewall of the reaction tube as the grounding electrode, the conversion rate of hydrogen sulfide can be more significantly improved when the high-flux low-temperature plasma reactor provided by the present application is used to carry out the decomposition reaction of hydrogen sulfide.

[0069] Preferably, the grounding electrode of the present application has conductive properties and can be attached to the surface of the barrier medium.

[0070] The material forming the center high-voltage electrode is a conductive material, and preferably, the material forming the center high-voltage electrode is selected from at least one of graphite tube, metal rod, metal tube and graphite rod. The metal rod and metal tube can include elemental metal rod, alloy metal rod, elemental metal tube and alloy metal tube. The material forming the center high-voltage electrode of the present application can be other rod-shaped and tubular materials with conductive properties.

[0071] The present application can maintain the temperature of the reactor with a jacket structure, for example, between 119-444.6℃, by introducing a heat-conducting medium in the area between the outer wall of the inner cylinder and the inner wall of the outer cylinder, to ensure that the sulfur produced by the decomposition of hydrogen sulfide flows out of the discharge area in liquid form.

[0072] The high-flux low-temperature plasma reactor of the present application can also be loaded with a catalyst capable of catalyzing the decomposition of hydrogen sulfide into elemental sulfur and hydrogen. The catalyst is preferably loaded in the inner cylinder of the reactor. The present application does not have special requirements for the loading volume and type of the catalyst. As for the type of catalyst, for example, it can be any one or more of the catalysts disclosed in CN102408095A, CN101590410A and CN103495427A.

[0073] The high-flux low-temperature plasma reactor provided by the present application does not have special limitations on the conditions of the decomposition reaction involved in the decomposition of hydrogen sulfide. Various conditions involved in the conventional plasma decomposition method of hydrogen sulfide in the art can be used for decomposition. The conditions for the decomposition of hydrogen sulfide are exemplarily listed in the embodiment part of the present application, and the person skilled in the art should not understand it as a limitation of the present application.

[0074] As described above, the second aspect of the present application provides a method for decomposing hydrogen sulfide, which is implemented in the high-flux low-temperature plasma reactor described in the first aspect above, and the method comprises: introducing a raw gas containing hydrogen sulfide into each reaction tube of the inner cylinder of the high-flux low-temperature plasma reactor under dielectric barrier discharge conditions to carry out a decomposition reaction of hydrogen sulfide, and the obtained stream after decomposition is led out by the product outlet, and the temperature required by the high-flux low-temperature plasma reactor is maintained by continuously introducing a heat-conducting medium into the outer cylinder of the high-flux low-temperature plasma reactor through the heat-conducting medium inlet and leading out the heat-conducting medium through the heat-conducting medium outlet, and the dielectric barrier discharge is formed by the ground electrode, the barrier medium and the central high-voltage electrode.

[0075] The high-flux low-temperature plasma reactor provided by the present application does not have special restrictions on the conditions of the decomposition reaction involved in the decomposition of hydrogen sulfide, and can carry out decomposition under various conditions involved in the conventional plasma decomposition method of hydrogen sulfide in the art. The conditions for decomposing hydrogen sulfide are exemplarily listed in the embodiment part of the present application, and those skilled in the art should not understand it as a limitation of the present application.

[0076] In the present application, the material forming the outer cylinder is not particularly limited, as long as the material forming the outer cylinder can withstand the set temperature of the heat-conducting medium.

[0077] The high-flux low-temperature plasma reactor provided by the present application does not have special restrictions on the concentration of hydrogen sulfide in the gas at the reactor inlet, for example, the concentration of hydrogen sulfide in the gas can be 0.01-100% by volume.

[0078] The following will be described in combination with Figure 1 The structure of a preferred embodiment of the high-flux low-temperature plasma reactor of the present application is provided, in particular:

[0079] The reactor has a jacketed cylinder structure, and the reactor comprises:

[0080] The inner cylinder 1 is provided with a reactor inlet 11 and a product outlet, respectively, and the inner cylinder 1 contains at least two parallelly arranged reaction tubes 14, the top and bottom of each reaction tube 14 are respectively correspondingly communicated, so that the raw material entering through the reactor inlet 11 can enter into each reaction tube 14, respectively, and the product generated in each reaction tube 14 can be led out through the product outlet;

[0081] an outer cylinder 2, which is nested outside the inner cylinder 1, and on which a heat conducting medium inlet 21 and a heat conducting medium outlet 22 are respectively provided, the heat conducting medium introduced by the heat conducting medium inlet 21 being able to be distributed between each of the reaction tubes 14 of the inner cylinder 1, and the heat conducting medium being led out by the heat conducting medium outlet 22;

[0082] a central high voltage electrode 3, which is respectively provided in each of the reaction tubes 14 of the inner cylinder 1;

[0083] a ground electrode 4, which is formed of a solid conductive material, and which forms at least part of the side wall of each of the reaction tubes 14 or which is respectively provided around the outer side wall of each of the reaction tubes 14;

[0084] a barrier medium, which forms at least part of the side wall of each of the reaction tubes 14 so that at least part of the barrier medium surrounds the central high voltage electrode 3 or which is provided around the inner side wall of each of the reaction tubes 14;

[0085] in each of the reaction tubes 14, the barrier medium is provided at a position so that the discharge region between the central high voltage electrode and the ground electrode is separated by the barrier medium,

[0086] in each of the reaction tubes 14, the distance L1 between the outer side wall of the central high voltage electrode 3 and the inner side wall of the barrier medium and the thickness D1 of the barrier medium are in a proportional relationship of L1:D1=(0.05-100):1.

[0087] Preferably, the barrier medium forms at least part of the side wall of each of the reaction tubes 14 so that at least part of the barrier medium surrounds the central high voltage electrode 3, and the ground electrode 4 is respectively provided around the outer side wall of each of the reaction tubes 14.

[0088] More preferably, the side wall of each of the reaction tubes 14 is entirely formed by the barrier medium.

[0089] Preferably, in each of the reaction tubes 14, the distance L1 between the outer side wall of the central high voltage electrode 3 and the inner side wall of the barrier medium and the thickness D1 of the barrier medium are in a proportional relationship of L1:D1=(0.1-30):1.

[0090] Preferably, the central high voltage electrodes 3 in each of the reaction tubes 14 are connected in parallel to each other.

[0091] Preferably, the reactor further comprises a grounding wire 5, which is arranged on the outer wall of the outer cylinder 2 and one end of which is connected with the grounding electrode 4 in each of the reaction tubes 14.

[0092] Preferably, the reactor inlet 11 is arranged at the upper part of the inner cylinder 1, and the product outlet is arranged at the lower part and / or the bottom of the inner cylinder 1.

[0093] According to one preferred embodiment, the product outlet comprises a gas product outlet 12 and a liquid product outlet 13, and the gas product outlet 12 is arranged at the lower part of the inner cylinder 1, and the liquid product outlet 13 is arranged at the bottom of the inner cylinder 1.

[0094] Preferably, each of the reaction tubes 14 has the same size.

[0095] Preferably, the gas product outlet 12 is arranged below all the discharge regions, and the ratio between the height H1 of the arrangement position of the gas product outlet 12 relative to the bottom of the inner cylinder 1 and the length L2 of the discharge region is H1 : L2 = 1 : (0.05-25000); preferably H1 : L2 = 1 : (0.1-10000); more preferably H1 : L2 = 1 : (0.5-1000).

[0096] Preferably, the heat-conducting medium inlet 21 and the heat-conducting medium outlet 22 are arranged at the lower part and the upper part of the outer cylinder 2, respectively.

[0097] The following provides another preferred embodiment for decomposing hydrogen sulfide by using the high-flux low-temperature plasma reactor of the present application:

[0098] Nitrogen is introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet to remove air in the discharge region, and the gas is led out from the product outlet. At the same time, heat-conducting medium is introduced into the outer cylinder from the heat-conducting medium inlet, and the introduced heat-conducting medium is led out from the heat-conducting medium outlet. The temperature of the heat-conducting medium is maintained at the required temperature of the system reaction. Then, raw gas containing hydrogen sulfide is introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet, and the raw gas fills each of the reaction tubes. After the flow of the raw gas is stable, the high-voltage power supply is turned on, and the plasma discharge field is formed between the central high-voltage electrode and the grounding electrode by adjusting the voltage and the frequency. Hydrogen sulfide gas is ionized in the discharge region and decomposed into hydrogen and elemental sulfur. The elemental sulfur produced by the discharge slowly flows down along the inner cylinder wall and flows out from the product outlet.

[0099] The high-flux low-temperature plasma reactor provided by the present application has the following specific advantages:

[0100] (1) The reactor uses a conductive solid material as a grounding electrode. Compared with a liquid grounding electrode, this grounding electrode generates a larger micro-discharge current when combined with the structure of the present invention, which is more conducive to the discharge decomposition reaction of hydrogen sulfide molecules.

[0101] (2) The reactor is equipped with a jacket structure on the outside of the grounding electrode. The temperature of the reactor can be controlled by controlling the temperature of the heat-conducting medium in the jacket. This allows the sulfur produced by the decomposition of hydrogen sulfide to flow smoothly out of the discharge area, preventing the sulfur from solidifying and clogging the reactor, and ensuring that the discharge continues stably.

[0102] (3) The reactor controls the ratio of the distance L1 between the outer wall of the central high-voltage electrode and the inner wall of the barrier medium to the thickness D1 of the barrier medium as: L1:D1 = (0.05~100):1; more preferably L1:D1 = (0.1~30):1. With the structure of the reactor of the present invention, the conversion rate of hydrogen sulfide can be significantly improved and the decomposition energy consumption can be reduced.

[0103] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available.

[0104] In the following examples, the conversion rate of hydrogen sulfide is calculated using the following formula:

[0105] The thickness of the barrier medium is the same in the following examples and comparative examples.

[0106] Hydrogen sulfide conversion rate % = (Number of moles of hydrogen sulfide converted / Initial number of moles of hydrogen sulfide) × 100%

[0107] In the following examples, the energy consumption for decomposing hydrogen sulfide was obtained by measuring with an oscilloscope and calculating using Lissajous figures.

[0108] Example 1

[0109] use Figure 1 The high-flux low-temperature plasma reactor shown is used for the decomposition of hydrogen sulfide. The specific structure and structural parameters of the high-flux low-temperature plasma reactor are as follows:

[0110] The reactor includes:

[0111] An inner cylinder is provided with a reactor inlet, a gas product outlet and a liquid product outlet, and contains four parallel reaction tubes, the top and bottom of each reaction tube correspond to each other, so that the raw materials entering from the reactor inlet can enter each reaction tube, and the gaseous products produced in each reaction tube can be led out from the gas product outlet, and the liquid products produced in each reaction tube can be led out from the liquid product outlet, the four reaction tubes are of the same size, and the side walls of the reaction tubes are formed by a blocking medium, and the material forming the blocking medium is hard glass;

[0112] An outer cylinder is nested outside the inner cylinder, and is provided with a heat conducting medium inlet and a heat conducting medium outlet, the heat conducting medium introduced from the heat conducting medium inlet can be distributed between each reaction tube of the inner cylinder, and the heat conducting medium is led out from the heat conducting medium outlet;

[0113] A central high-voltage electrode is arranged at the central axis position of each reaction tube, the material forming the central high-voltage electrode is a stainless steel rod, and the central high-voltage electrodes in each reaction tube are connected in parallel;

[0114] A grounding electrode is arranged around the outer side wall of each reaction tube, the material forming the grounding electrode is a stainless steel foil, and the lower edge of the central high-voltage electrode in this embodiment is flush with the lower edge of the grounding electrode.

[0115] In each reaction tube, the ratio of the distance L1 between the outer side wall of the central high-voltage electrode and the inner side wall of the blocking medium to the thickness D1 of the blocking medium is 8:1;

[0116] The ratio between the height H1 of the gas product outlet relative to the bottom of the inner cylinder and the length L2 of the discharge area in each reaction tube is H1:L2=1:32;

[0117] The volume of the entire reactor inner cylinder of this embodiment is 1L.

[0118] In this embodiment, the mixed gas enters the reactor inner cylinder from the upper part of the reactor inner cylinder, and the gaseous products are led out from the gas product outlet located at the lower part of the reactor inner cylinder, and the elemental sulfur is led out from the liquid product outlet located at the bottom of the reactor; and the heat conducting medium of this embodiment is introduced from the lower part of the outer cylinder of the reactor, and is led out from the upper part of the outer cylinder of the reactor.

[0119] Operation steps of the high-flux low-temperature plasma reactor:

[0120] Nitrogen gas was introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet to remove air in the discharge area, and the gas was led out from the gas product outlet and the liquid product outlet. At the same time, the heat-conducting medium (specifically, dimethyl silicone oil) was introduced into the outer cylinder from the heat-conducting medium inlet, and the introduced heat-conducting medium was led out from the heat-conducting medium outlet, and the temperature of the heat-conducting medium was maintained at 145°C.

[0121] Then H2S / Ar mixed gas with a H2S volume fraction of 65% was introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet, and the flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge area was 9.7s. After the H2S / Ar mixed gas was introduced into the reactor for 30min, the alternating-current high-voltage power supply was turned on, and the plasma discharge field between the center high-voltage electrode and the grounding electrode was formed by adjusting the voltage and the frequency. The discharge conditions were as follows: the voltage was 13.8kV, the frequency was 0.8kHz, and the current was 2.2A. The hydrogen sulfide gas was ionized in the discharge area and decomposed into hydrogen and elemental sulfur, and the elemental sulfur generated by the discharge slowly flowed down along the inner cylinder wall and flowed out from the liquid product outlet. The reaction gas flowed out from the gas product outlet.

[0122] Results: The H2S conversion rate was 73.6% after the hydrogen sulfide decomposition reaction of this example was carried out for 20min; and no abnormality was found after the discharge was continued for 100h, and the discharge state and the H2S conversion rate were both stable. The decomposition energy consumption of this example was 14.2eV / H2S molecule (the energy required for the decomposition of 1 molecule of H2S was 14.2eV).

[0123] Comparative Example 1

[0124] This comparative example used a high-flux low-temperature plasma reactor similar to that of Example 1 to carry out a hydrogen sulfide decomposition reaction, except that:

[0125] The grounding electrode in this comparative example was a liquid grounding electrode, and the molar ratio of LiCl and AlCl3 in the molten state was 1:1, and the liquid grounding electrode was also a heat-conducting medium, and the temperature was maintained at 145°C, and the liquid grounding electrode was placed in the outer cylinder of the reactor.

[0126] The flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge area was 20.5s.

[0127] The volume of the entire inner cylinder of the reactor in this comparative example was 0.05L.

[0128] The rest were the same as in Example 1.

[0129] And this comparative example used the same operation method as Example 1 to carry out a hydrogen sulfide decomposition reaction.

[0130] Results: The H2S conversion rate of this comparative example was 14.9% after the hydrogen sulfide decomposition reaction was continuously carried out for 20 min, and the H2S conversion rate was reduced to 6.9% after the discharge was continuously carried out for 1.5 h.

[0131] The decomposition energy consumption of this comparative example was 111 eV / H2S molecule.

[0132] Comparative Example 2

[0133] This comparative example was carried out using a low-temperature plasma reactor similar to that of Comparative Example 1, except that:

[0134] In each reaction tube, the ratio of the distance L1 between the outer side wall of the central high-voltage electrode and the inner side wall of the blocking medium to the thickness D1 of the blocking medium was 0.01:1.

[0135] The mixed gas flow rate was controlled so that the average residence time of the gas in the discharge area was 20.5 s.

[0136] The volume of the inner cylinder of this comparative example was 0.02 L.

[0137] The rest was the same as in Comparative Example 1.

[0138] Results: The H2S conversion rate of this comparative example was 22.5% after the hydrogen sulfide decomposition reaction was continuously carried out for 20 min, and the H2S conversion rate was reduced to 9.2% after the discharge was continuously carried out for 1.5 h.

[0139] The decomposition energy consumption of this comparative example was 143 eV / H2S molecule.

[0140] Example 2

[0141] This example carried out a hydrogen sulfide decomposition reaction using a high-throughput low-temperature plasma reactor similar to that of Example 1, except that in this example:

[0142] The entire side wall of the inner cylinder was formed by a grounding electrode, and the material forming the grounding electrode was a stainless steel metal foil;

[0143] The blocking medium was arranged around the inner side wall of the inner cylinder;

[0144] The ratio of the distance L1 between the outer side wall of the central high-voltage electrode and the inner side wall of the blocking medium to the thickness D1 of the blocking medium was 18:1;

[0145] The proportional relationship between H1 and the length L2 of the discharge area containing the blocking medium was: H1:L2 = 1:95.

[0146] In this embodiment, H2S / Ar mixed gas with a H2S volume fraction of 65% is introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet, and the flow rate of the mixed gas is controlled so that the average residence time of the gas in the discharge zone is 10.8 s. After the H2S / Ar mixed gas is introduced into the reactor for 30 min, the alternating-current high-voltage power supply is turned on, and the plasma discharge field is formed between the center high-voltage electrode and the grounded electrode by adjusting the voltage and the frequency. The discharge conditions are as follows: the voltage is 14.9 kV, the frequency is 1.6 kHz, and the current is 1.95 A.

[0147] The rest are the same as in Example 1.

[0148] Results: The H2S conversion rate was 74.2% after the hydrogen sulfide decomposition reaction in this embodiment was continuously performed for 20 min; and no abnormality was observed after the discharge was continuously performed for 100 h, and the discharge state and the H2S conversion rate were both stable. The decomposition energy consumption of this embodiment is 14.8 eV / H2S molecule.

[0149] Example 3

[0150] In this embodiment, the decomposition reaction of hydrogen sulfide is performed by using a high-flux low-temperature plasma reactor similar to that in Example 1, except that in this embodiment:

[0151] The entire side wall of the inner cylinder is formed by the grounded electrode, and the material forming the grounded electrode is a copper foil;

[0152] The blocking medium is arranged around the inner side wall of the inner cylinder;

[0153] The ratio of the distance L1 between the outer side wall of the center high-voltage electrode and the inner side wall of the blocking medium to the thickness D1 of the blocking medium is 0.5:1;

[0154] The proportional relationship between H1 and the length L2 of the discharge zone containing the blocking medium is H1:L2=1:220.

[0155] In this embodiment, H2S / Ar mixed gas with a H2S volume fraction of 65% is introduced into the inner cylinder of the high-flux low-temperature plasma reactor from the reactor inlet, and the flow rate of the mixed gas is controlled so that the average residence time of the gas in the discharge zone is 10.8 s. After the H2S / Ar mixed gas is introduced into the reactor for 30 min, the alternating-current high-voltage power supply is turned on, and the plasma discharge field is formed between the center high-voltage electrode and the grounded electrode by adjusting the voltage and the frequency. The discharge conditions are as follows: the voltage is 14.9 kV, the frequency is 1.6 kHz, and the current is 1.95 A.

[0156] The rest are the same as in Example 1.

[0157] Results: The H2S conversion rate of the hydrogen sulfide decomposition reaction of this example was 74.0% after 20 min of continuous reaction, and no abnormality was observed after 100 h of continuous discharge, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this example was 15.6 eV / H2S molecule.

[0158] Example 4

[0159] This example used a similar plasma reactor as in Example 1 to perform the decomposition reaction of hydrogen sulfide, except that in this example:

[0160] The ratio of the distance L1 between the outer wall of the central high-voltage electrode and the inner wall of the blocking medium to the thickness D1 of the blocking medium was 35:1.

[0161] The rest were the same as in Example 1.

[0162] Results: The H2S conversion rate of the hydrogen sulfide decomposition reaction of this example was 74.0% after 20 min of continuous reaction, and no abnormality was observed after 100 h of continuous discharge, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this example was 15.6 eV / H2S molecule.

[0163] From the above results, it can be seen that the application of the high-flux low-temperature plasma reactor provided by the present application to the decomposition of hydrogen sulfide can significantly improve the conversion rate of hydrogen sulfide compared to the prior art, and the reactor provided by the present application can maintain a high conversion rate of hydrogen sulfide for a long period of time at a low decomposition energy consumption.

[0164] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A high-flux low-temperature plasma reactor having a double-cylinder structure, comprising: an inner cylinder (1) provided with a reactor inlet (11) and a product outlet, respectively, and containing at least two parallel reaction tubes (14) in the inner cylinder (1), the top and bottom of each reaction tube (14) being respectively communicated, so that raw materials entering from the reactor inlet (11) can enter into each reaction tube (14), respectively, and the products generated in each reaction tube (14) can be led out by the product outlet; an outer cylinder (2) nested outside the inner cylinder (1), and provided with a heat-conducting medium inlet (21) and a heat-conducting medium outlet (22), respectively, the heat-conducting medium introduced from the heat-conducting medium inlet (21) can be distributed between each reaction tube (14) of the inner cylinder (1), and the heat-conducting medium is led out by the heat-conducting medium outlet (22); a central high-voltage electrode (3) provided in each reaction tube (14) of the inner cylinder (1), respectively; a grounding electrode (4) formed of solid conductive material, and forming at least part of the side wall of each reaction tube (14), or surrounding the outer side wall of each reaction tube (14), respectively; a barrier medium forming at least part of the side wall of each reaction tube (14) so that at least part of the barrier medium surrounds the central high-voltage electrode (3), or surrounding the inner side wall of each reaction tube (14); in each reaction tube (14), the barrier medium is arranged so that the discharge region between the central high-voltage electrode and the grounding electrode is spaced by the barrier medium, in each reaction tube (14), the distance L1 between the outer side wall of the central high-voltage electrode (3) and the inner side wall of the barrier medium and the thickness D1 of the barrier medium have a proportional relationship of L1:D1=(0.1-30):1; the reactor inlet (11) is arranged at the upper part of the inner cylinder (1), and the product outlet is arranged at the lower part and / or the bottom of the inner cylinder (1); the product outlet comprises a gas product outlet (12) and a liquid product outlet (13), and the gas product outlet (12) is arranged at the lower part of the inner cylinder (1), and the liquid product outlet (13) is arranged at the bottom of the inner cylinder (1); the gas product outlet (12) is arranged below the discharge region, and the proportional relationship between the height H1 of the arrangement position of the gas product outlet (12) relative to the bottom of the inner cylinder (1) and the length L2 of the discharge region is H1:L2=1:(0.5-1000). ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The high flux low temperature plasma reactor of claim 1, wherein, The blocking medium forms at least part of the side wall of each reaction tube (14) so that at least part of the blocking medium surrounds the central high-voltage electrode (3), and the grounding electrode (4) surrounds the outer side wall of each reaction tube (14) respectively.

3. The high flux low temperature plasma reactor of claim 1, wherein, The side wall of each reaction tube (14) is entirely formed by the blocking medium.

4. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The central high-voltage electrodes (3) in each reaction tube (14) are connected in parallel to each other.

5. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The material forming the blocking medium is an electrically insulating material.

6. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The material forming the blocking medium is selected from at least one of glass, quartz, ceramic, enamel, polytetrafluoroethylene and mica.

7. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The reactor further comprises a grounding wire (5) arranged on the outer side wall of the outer cylinder (2) and connected at one end to the grounding electrode (4) in each reaction tube (14).

8. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The size of each reaction tube (14) is the same.

9. The high flux low temperature plasma reactor of claim 1 or 2, wherein, The heat-conducting medium inlet (21) and the heat-conducting medium outlet (22) are arranged on the lower part and the upper part of the outer cylinder (2) respectively.

10. The high flux low temperature plasma reactor of claim 1, wherein, The material forming the grounding electrode (4) is selected from a graphite tube, a metal tube, a metal foil or a metal mesh.

11. The high flux low temperature plasma reactor of claim 1, wherein, The material forming the central high-voltage electrode (3) is selected from at least one of a graphite tube, a metal rod, a metal tube and a graphite rod.

12. A method of decomposing hydrogen sulfide, the method being carried out in the high flux low temperature plasma reactor of any one of claims 1-11, the method comprising: Under the condition of dielectric barrier discharge, a raw gas containing hydrogen sulfide is introduced from the reactor inlet into each reaction tube of the inner cylinder of the high-flux low-temperature plasma reactor for a decomposition reaction of hydrogen sulfide, and the obtained stream after decomposition is led out by the product outlet, and the temperature required by the high-flux low-temperature plasma reactor is maintained by continuously introducing a heat-conducting medium into the outer cylinder of the high-flux low-temperature plasma reactor from the heat-conducting medium inlet and leading out the heat-conducting medium from the heat-conducting medium outlet, and the dielectric barrier discharge is formed by the grounding electrode, the blocking medium and the central high-voltage electrode.

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