High-throughput plasma reactor and method of decomposing hydrogen sulfide

Abstract

This invention relates to the field of plasma chemistry and discloses a high-throughput plasma reaction device and a method for decomposing hydrogen sulfide, comprising: an inner cylinder (1) containing reaction tubes (14); an outer cylinder (2) nested outside the inner cylinder (1); a central high-voltage electrode (3); grounding electrodes (4) respectively surrounding or forming sidewalls on the outer walls of each of the reaction tubes (14); a blocking medium (6) disposed on at least a portion of the outer surface of the central high-voltage electrode (3); the ratio between the distance L1 between the outer wall of the blocking medium and the inner wall of the grounding electrode and the length L2 of the discharge region is: L1:L2 = 1:(0.5~6000). The high-throughput plasma reaction device provided by this invention can achieve continuous and stable hydrogen sulfide decomposition process at a significantly higher hydrogen sulfide conversion rate, and the device can achieve long-term operation.

Description

Technical Field

[0001] This invention relates to the field of plasma chemistry, specifically to a high-throughput plasma reaction apparatus and a method for decomposing hydrogen sulfide. Background Technology

[0002] Hydrogen sulfide (H2S) is a highly toxic, foul-smelling acidic gas that not only corrodes metals and other materials but also harms human health and pollutes the environment. Currently, large and medium-sized oil refineries in my country use the traditional Claus process to treat H2S-containing tail gas and recover sulfur. This method only recovers the sulfur from the hydrogen sulfide, but converts valuable hydrogen into water. From the perspective of comprehensive resource utilization, hydrogen resources are not effectively utilized in traditional hydrogen sulfide recovery processes. Therefore, the decomposition of hydrogen sulfide into sulfur and hydrogen has gradually become a key technological focus for researchers both domestically and internationally.

[0003] Currently, methods for hydrogen sulfide decomposition mainly include high-temperature decomposition, electrochemical methods, photocatalysis, and low-temperature plasma methods. Among these methods, high-temperature thermal decomposition is relatively mature in industrial technology. However, hydrogen sulfide thermal decomposition is strongly dependent on the reaction temperature and is limited by thermodynamic equilibrium; even at reaction temperatures above 1000℃, the conversion rate of hydrogen sulfide is only 20%. Furthermore, high-temperature conditions place high demands on reactor materials, increasing operating costs. 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 circulated within the system, thus reducing equipment efficiency and increasing energy consumption, all of which hinder its large-scale industrial application. While membrane technology can effectively separate products to break the equilibrium limitation and improve the hydrogen sulfide conversion rate, the thermal decomposition temperature often exceeds the membrane's ultimate heat resistance temperature, damaging the membrane material structure. Electrochemical methods suffer from drawbacks such as numerous operating steps, severe equipment corrosion, poor reaction stability, and low efficiency. Photocatalytic decomposition of hydrogen sulfide mainly draws on research into photocatalytic water splitting, with research focusing on the development of highly efficient semiconductor photocatalysts. Using solar energy to decompose hydrogen sulfide has advantages such as low energy consumption, mild reaction conditions, and simple operation, making it a relatively economical method. However, this method also suffers from problems such as small processing capacity, low catalytic efficiency, and easy catalyst deactivation.

[0004] Compared with other decomposition methods, the low-temperature plasma method has advantages such as simple operation, small device size, and high energy efficiency. Furthermore, the reactions involved are highly controllable, allowing for flexible application in situations with small processing volumes and difficulties in centralized processing. In addition, due to its high energy density and shortened reaction time, it can effectively decompose hydrogen sulfide at relatively low temperatures, making it suitable for various scales, dispersed layouts, and variable production conditions. Moreover, while recovering sulfur, the low-temperature plasma method also recovers hydrogen resources, enabling the resource utilization of hydrogen sulfide.

[0005] Currently, researchers both domestically and internationally have conducted extensive research on low-temperature plasma decomposition of hydrogen sulfide, using discharge forms that mainly 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, describes the decomposition of hydrogen sulfide using a contracted normal glow discharge method. Under conditions of 0.02 MPa pressure and 2000–4000 K temperature, the lowest decomposition energy consumption for hydrogen sulfide was 2.35 eV / H₂S. However, this reaction requires high temperature and low pressure, making it difficult to implement under demanding conditions.

[0007] The literature "International Journal of Hydrogen Energy", 2012, 37: 10010-10019 describes the decomposition of hydrogen sulfide using microwave plasma. Under atmospheric pressure and a temperature of 2400K, hydrogen sulfide can be completely decomposed. However, the hydrogen and sulfur after decomposition will rapidly recombine at high temperatures to regenerate hydrogen sulfide, and there is currently no corresponding quenching measure.

[0008] The literature *Chemical Engineering Science*, 2009, 64(23): 4826-4834, investigated the decomposition of H2S to produce hydrogen and sulfur using pulsed corona discharge. The reactor employed a tubular structure, and the effects of pulse forming capacitance, discharge voltage, and pulse frequency on H2S conversion rate and decomposition energy efficiency were examined under a fixed power of 100W. The results showed that, under constant power conditions, low pulse forming capacitance, low discharge voltage, and high pulse frequency were beneficial for achieving high H2S decomposition energy efficiency. Furthermore, compared to using Ar and N2 as balance gases, using an Ar-N2 mixture as the balance gas resulted in a higher H2S conversion rate. At an Ar / N2 / H2S volume fraction of 46% / 46% / 8%, a discharge power of 60W, and a pulse forming capacitance of 720pF, the lowest H2S decomposition energy consumption was 4.9 eV / H2S, but the H2S conversion rate was only about 30%. Additionally, the flow rate of this reaction system was only 1.18 × 10⁻⁶. -4 SCMs -1 Such a reaction with low flow rate, low concentration, and low conversion rate has no practical significance in industrial production.

[0009] The literature *Journal of Applied Physics*, 1998, 84(3): 1215-1221, investigated the decomposition reaction of H2S using sliding arc discharge. The method involved diluting H2S with air to a concentration of 0–100 ppm and examining the effects of gas flow rate, reaction chamber size, and frequency on the H2S decomposition reaction under a total gas flow rate of 0–100 L / min. Experimental results showed that low gas flow rate, small disk spacing, and low frequency were beneficial for obtaining higher H2S conversion rates. Under optimized discharge conditions, the H2S conversion rate could reach 75–80%. However, the energy consumption for H2S decomposition was as high as 500 eV / H2S, and this low-concentration, high-energy-consumption reaction showed no industrial application potential.

[0010] Dielectric barrier discharge can typically be generated at atmospheric pressure and at relatively low temperatures. Furthermore, the presence of the dielectric restricts the growth of the discharge current, preventing complete gas breakdown and the formation of sparks or arcs. This facilitates the generation of large-volume, stable plasmas and offers promising prospects for industrial applications.

[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 an improved ozone generator, and studied the effects of reaction temperature, H2S feed concentration, injection power, and the addition of H2, Ar, N2, etc. on H2S conversion rate and energy efficiency. The experiment found that the addition of Ar can promote the decomposition of H2S. 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 hydrogen production energy consumption 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 dielectric barrier discharge and photocatalyst to synergistically decompose hydrogen sulfide. The method involves filling a plasma region with a solid catalyst that has photocatalytic activity. 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, discusses Al2O3 and MoO2. x MoOx / Al2O3, CoOx / Al2O3, and NiO / Al2O3 catalysts were used to fill the discharge region, and H2S decomposition was studied using dielectric barrier discharge and catalysts. The results showed that MoOx / Al2O3 and CoOx / Al2O3 catalysts had good performance; among them, when MoOx / Al2O3 catalyst was used, with a total H2S / Ar flow rate of 150 mL / min, an H2S concentration of 5% by volume, an injection specific energy (SIE) of 0.92 kJ / L, and a catalyst packing length of 10% of the bed, the highest H2S conversion rate was approximately 48%. However, the hydrogen sulfide concentration was low in this reaction process, and the sulfur produced by decomposition deposited inside the reactor. With prolonged time, the catalyst activity decreased, the discharge stability decreased, and the hydrogen sulfide conversion rate gradually decreased.

[0014] CN103204466A discloses a temperature-controlled hydrogen sulfide decomposition device and method. This device is characterized by a central high-voltage electrode made of metal and a temperature-controlled circulating liquid as the grounding electrode. Temperature control via the liquid grounding electrode ensures the continuous and stable decomposition of hydrogen sulfide. CN103204467A discloses a device and method for the continuous and stable decomposition of hydrogen sulfide to produce hydrogen. This prior art is characterized by a central high-voltage electrode made of metal and a temperature-controlled circulating liquid as the grounding electrode. Temperature control is achieved via the liquid grounding electrode. The raw material is introduced circumferentially and passes through the discharge zone in a spiral pattern in a counter-axial direction, allowing the generated sulfur to be promptly separated by centrifugation. However, in order to ensure that hydrogen sulfide is decomposed as completely as possible, the methods disclosed in CN103204466A and CN103204467A require controlling the flow rate of hydrogen sulfide to increase its residence time in the reactor inner cylinder and controlling the size of the inner cylinder to increase the electrical energy obtained per unit volume of gas in the inner cylinder. Furthermore, since current technology cannot provide a more powerful power source, even if the methods disclosed in CN103204466A and CN103204467A control the residence time of hydrogen sulfide and the size of the inner cylinder to increase the electrical energy obtained per unit volume of gas in the inner cylinder, the maximum conversion rate of hydrogen sulfide can only reach about 20%. Moreover, when the maximum conversion rate of hydrogen sulfide reaches about 20%, the energy consumption of the hydrogen sulfide decomposition reaction is quite high, which is not suitable for large-scale industrial applications. Furthermore, the methods disclosed in CN103204466A and CN103204467A have the drawback that there are very few types of liquid grounding electrodes available. The salt solutions disclosed therein can generally only maintain the reactor temperature below 100°C. Below 100°C, elemental sulfur is generally solid, which can easily cause the reactor to become clogged. Summary of the Invention

[0015] The purpose of this invention is to overcome the shortcomings of existing technologies in decomposing hydrogen sulfide into hydrogen and elemental sulfur, such as low hydrogen sulfide conversion rate, high energy consumption, and inability to achieve large-flow hydrogen sulfide treatment. This invention provides a new high-throughput plasma reactor and a method for decomposing hydrogen sulfide using the high-throughput plasma reactor.

[0016] To achieve the above objectives, a first aspect of the present invention provides a high-throughput plasma reaction apparatus having a jacketed structure, and the reaction apparatus comprising:

[0017] 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 communicating with each other, 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.

[0018] An outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively provided on the outer cylinder. The heat-conducting medium introduced through the heat-conducting medium inlet can be distributed between each of the reaction tubes in the inner cylinder, and the heat-conducting medium is led out through the heat-conducting medium outlet.

[0019] A central high-voltage electrode is disposed in each of the reaction tubes in the inner cylinder;

[0020] The grounding electrode is formed of a solid conductive material, and the grounding electrode is respectively arranged around the inner sidewall of each of the reaction tubes, or the grounding electrode is formed in at least part of the sidewall of each of the reaction tubes.

[0021] A blocking medium is disposed on at least a portion of the outer surface of the central high-voltage electrode, such that the blocking medium covers the outer surface of the central high-voltage electrode, which extends at least partially into the inner cylinder.

[0022] In each of the reaction tubes, the blocking medium is positioned such that the discharge area between the central high-voltage electrode and the grounding electrode is separated by the blocking medium, and the ratio between the distance L1 between the outer wall of the blocking medium and the inner wall of the grounding electrode and the length L2 of the discharge area is: L1:L2 = 1:(0.5~6000).

[0023] In a second aspect, the present invention provides a method for decomposing hydrogen sulfide, which is implemented in the high-flux plasma reactor described in the first aspect of the present invention. The method includes: introducing a feed gas containing hydrogen sulfide from the reactor inlet into the reaction tube of the inner cylinder of the high-flux plasma reactor under dielectric barrier discharge conditions to carry out the decomposition reaction of hydrogen sulfide; the stream obtained after decomposition is led out from the product outlet; and maintaining the temperature required by the high-flux plasma reactor by continuously introducing a heat-conducting medium into the outer cylinder of the high-flux plasma reactor from the heat-conducting medium inlet and leading out the heat-conducting medium from the heat-conducting medium outlet. The dielectric barrier discharge is formed by a grounding electrode, a barrier medium, and a central high-voltage electrode in each of the reaction vessels.

[0024] The high-throughput plasma reactor provided by this invention is a jacketed dielectric barrier discharge reactor with a coaxial structure. Its basic structure mainly includes a central high-voltage electrode, a solid grounding electrode, and a barrier dielectric. This jacketed structure allows the heat-conducting dielectric to circulate and heat or cool the discharge reactor, thereby achieving flexible temperature control of the discharge region. Specifically, by controlling the ratio between the distance L1 between the outer wall of the barrier dielectric and the inner wall of the grounding electrode and the length L2 of the discharge region to L1:L2 = 1:(0.5~6000), this invention can significantly improve the hydrogen sulfide conversion rate compared to existing technologies.

[0025] The high-throughput plasma reactor provided by this invention has the advantages of high hydrogen sulfide conversion rate, low energy consumption, and the ability to process large flow rates of hydrogen sulfide.

[0026] Furthermore, the high-throughput plasma reaction device provided by this invention can generate uniform and efficient dielectric barrier discharge, thereby efficiently decomposing hydrogen sulfide directly into hydrogen and sulfur.

[0027] Furthermore, the high-throughput plasma reactor provided by this invention can achieve continuous and stable hydrogen sulfide decomposition at a significantly higher hydrogen sulfide conversion rate, and the device can operate for extended periods. Moreover, the high-throughput plasma reactor provided by this invention can also be used for the treatment of high-flow-rate, high-concentration hydrogen sulfide. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a preferred embodiment of the high-throughput plasma reaction device 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

[0038] 6. Barrier medium Detailed Implementation

[0039] 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.

[0040] As described above, the present invention provides a high-throughput plasma reaction device, which has a jacketed structure and includes:

[0041] 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 communicating with each other, 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.

[0042] An outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively provided on the outer cylinder. The heat-conducting medium introduced through the heat-conducting medium inlet can be distributed between each of the reaction tubes in the inner cylinder, and the heat-conducting medium is led out through the heat-conducting medium outlet.

[0043] A central high-voltage electrode is disposed in each of the reaction tubes in the inner cylinder;

[0044] The grounding electrode is formed of a solid conductive material, and the grounding electrode is respectively arranged around the inner sidewall of each of the reaction tubes, or the grounding electrode is formed in at least part of the sidewall of each of the reaction tubes.

[0045] A blocking medium is disposed on at least a portion of the outer surface of the central high-voltage electrode, such that the blocking medium covers the outer surface of the central high-voltage electrode, which extends at least partially into the inner cylinder.

[0046] In each of the reaction tubes, the blocking medium is positioned such that the discharge area between the central high-voltage electrode and the grounding electrode is separated by the blocking medium, and the ratio between the distance L1 between the outer wall of the blocking medium and the inner wall of the grounding electrode and the length L2 of the discharge area is: L1:L2 = 1:(0.5~6000).

[0047] The distinction between "sidewall" and "outer sidewall" and "inner sidewall" in this invention is as follows: "outer sidewall" and "inner sidewall" respectively refer to the outer surface and inner surface of the "sidewall".

[0048] In this invention, the structure formed by the various reaction tubes that are connected at the top and bottom is called the inner cylinder.

[0049] Each of the reaction tubes of the present invention is provided with a central high-voltage electrode, preferably located at the core of each reaction tube, which is beneficial to the uniform discharge of the reaction device of the present invention.

[0050] Regarding the definition of the discharge region, this invention should clarify that: the discharge region is the area between the outer wall of the blocking medium and the inner wall of the grounding electrode, and the upper and lower edges of the discharge region respectively end at the upper and lower edges of the overlapping segment of the orthographic projection of the grounding electrode on the central high-voltage electrode and the orthographic projection of the blocking medium on the central high-voltage electrode. Therefore, the length L2 of the discharge region is the overlap length of the orthographic projection of the grounding electrode on the central high-voltage electrode and the orthographic projection of the blocking medium on the central high-voltage electrode.

[0051] The jacketed structure design of the present invention enables the heat-conducting medium to circulate in the shell, ensuring the discharge intensity while maintaining the entire reaction device within a certain temperature range. This allows the generated sulfur to flow out of the reaction device in liquid form, effectively preventing the solidification of sulfur generated from the decomposition of hydrogen sulfide. It also enables the decomposition process to achieve continuous and stable long-term operation while achieving a high conversion rate.

[0052] In this invention, in order to further improve the conversion rate of hydrogen sulfide, it is preferred that L1:L2 = 1:(2~3000).

[0053] In particular, the inventors of this invention have discovered that when the ratio of L1:L2 is controlled within the aforementioned range of this invention, and the ratio between the distance L1 between the outer wall of the barrier medium and the inner wall of the grounding electrode and the thickness D1 of the barrier medium is controlled to be L1:D1 = (0.05 to 100):1, and particularly preferably L1:D1 = (0.1 to 30):1, when hydrogen sulfide is decomposed using the high-throughput plasma reaction apparatus of this invention, a higher hydrogen sulfide decomposition conversion rate can be achieved with relatively lower decomposition energy consumption.

[0054] The blocking medium of the present invention is disposed on at least a portion of the outer surface of the central high-voltage electrode. The blocking medium can be fixed to the outer surface of the central high-voltage electrode in any way that can fix it, or the blocking medium can be coated on the outer surface of the central high-voltage electrode in the form of a coating.

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

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

[0057] Preferably, the reaction apparatus further includes a grounding wire, which is disposed on the outer wall of the outer cylinder and one end is electrically connected to the grounding electrode in each of the reaction tubes.

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

[0059] According to a preferred embodiment, the product outlet includes a gaseous product outlet and a liquid product outlet, wherein the gaseous product outlet is located at the lower part of the inner cylinder, and the liquid product outlet is located at the bottom of the inner cylinder.

[0060] According to a preferred embodiment, all the reaction tubes are of the same size. "Same size" means that all the reaction tubes are identical in size and shape. The arrangement of the reaction tubes in this invention is not particularly limited; their cross-section can be an equilateral triangle, a regular hexagon, a circle, etc.

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

[0062] The ratio of the aperture of the reactor inlet to the aperture of the gas product outlet can be (0.1 to 120):1.

[0063] The ratio between the length of each reaction tube and the inner diameter of each reaction tube in this invention can be (0.5 to 500):1.

[0064] In a preferred embodiment, the gas product outlet is located below all the discharge areas, and 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 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 transfer medium inlet and the heat transfer medium outlet are respectively located at the lower and upper parts of the outer cylinder.

[0066] In this invention, the inner cylinder is mainly used for the decomposition reaction of hydrogen sulfide, while the outer cylinder is mainly used to provide the required temperature for the decomposition reaction in the inner cylinder. Therefore, those skilled in the art can adjust and select a suitable size ratio between the inner and outer cylinders according to this application.

[0067] The reactor inlet of the present invention can be configured such that the raw material gas entering the inner cylinder is parallel to or at a certain angle to the inner diameter of the inner cylinder, for example, it can be tangentially configured.

[0068] All inner diameters mentioned in this invention refer to diameters.

[0069] Preferably, the material forming the grounding electrode is selected from graphite tubes, metal tubes, metal foils, or metal meshes. The solid grounding electrode of the present invention generates a larger micro-discharge current under a certain injected power, which is more conducive to the bond-breaking decomposition reaction of hydrogen sulfide. The metal tubes and metal foils in the materials forming the grounding electrode can include elemental metal tubes, elemental metal foils, alloy metal tubes, and alloy metal foils. The inventors of the present invention have discovered that when a solid conductive material is used as the grounding electrode, surrounding or forming the inner wall of the reaction tube, the conversion rate of hydrogen sulfide during the hydrogen sulfide decomposition reaction using the high-flux plasma reaction apparatus provided by the present invention can be significantly improved.

[0070] The material forming the central high-voltage electrode is a conductive material. Preferably, the material forming the central high-voltage electrode is selected from at least one of graphite tubes, metal rods, metal tubes, graphite rods, metal powder, and graphite powder. The metal rods and metal tubes may include elemental metal rods, alloy metal rods, elemental metal tubes, and alloy metal tubes. The metal powder may include elemental metal powder, alloy metal powder, a mechanical mixture of elemental metal powder and / or alloy metal powder, or a mixture of metal powder and graphite powder. The material forming the central high-voltage electrode of the present invention may also be other rod-shaped and tubular materials with conductive properties.

[0071] The present invention can maintain the temperature of the reaction device with a jacket structure between, for example, 119 to 444.6°C by introducing a heat-conducting medium in the region between the outer wall of the inner cylinder and the inner wall of the outer cylinder, so as to ensure that the sulfur produced by the decomposition of hydrogen sulfide flows out of the discharge zone in liquid form.

[0072] The high-flux plasma reactor of the present invention may also be filled with a catalyst capable of catalyzing the decomposition of hydrogen sulfide into elemental sulfur and hydrogen. The catalyst is preferably filled in the inner cylinder of the reactor. The present invention does not have particular requirements regarding the filling volume or type of the catalyst. Regarding the type of catalyst, it can be any one or more of the catalysts disclosed in CN102408095A, CN101590410A, and CN103495427A.

[0073] As previously described, a second aspect of the present invention provides a method for decomposing hydrogen sulfide, which is implemented in the high-throughput plasma reactor described in the first aspect of the present invention. The method includes: introducing a feed gas containing hydrogen sulfide from a reactor inlet into a reaction tube of the inner cylinder of the high-throughput plasma reactor under dielectric barrier discharge conditions to carry out a hydrogen sulfide decomposition reaction; the resulting stream after decomposition is led out from the product outlet; and maintaining the required temperature of the high-throughput plasma reactor by continuously introducing a thermally conductive medium from a thermally conductive medium inlet into the outer cylinder of the high-throughput plasma reactor and leading out the thermally conductive medium from a thermally conductive medium outlet. The dielectric barrier discharge is formed by a grounding electrode, a barrier medium, and a central high-voltage electrode in each of the reaction vessels.

[0074] The high-throughput plasma reaction device provided by the present invention does not impose any particular restrictions on the conditions of the decomposition reaction involved in the decomposition of hydrogen sulfide. It can be used for decomposition under various conditions involved in conventional plasma decomposition methods for hydrogen sulfide in the art. The embodiments of the present invention exemplarily list the conditions for decomposing hydrogen sulfide, which should not be construed as limiting the present invention by those skilled in the art.

[0075] In this invention, there are no particular limitations on the material used to form the outer cylinder, as long as the material used to form the outer cylinder can withstand the set temperature of the heat-conducting medium.

[0076] The high-throughput plasma reactor provided by this invention does not have a particular limitation 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 to 100% by volume.

[0077] The following combination Figure 1 A preferred embodiment of the high-throughput plasma reactor of the present invention is provided, specifically:

[0078] The reaction apparatus has a jacketed structure and includes:

[0079] The inner cylinder 1 is provided with a reactor inlet 11 and a product outlet 13. The inner cylinder 1 contains at least two parallel reaction tubes 14, with the top and bottom of each reaction tube 14 communicating with each other, so that the raw material entering from the reactor inlet 11 can enter each of the reaction tubes 14, and the product generated in each of the reaction tubes 14 can be led out from the product outlet.

[0080] The outer cylinder 2 is nested outside the inner cylinder 1, and the outer cylinder 2 is provided with a heat-conducting medium inlet 21 and a heat-conducting medium outlet 22. The heat-conducting medium introduced by the heat-conducting medium inlet 21 can be distributed between each of the reaction tubes 14 in the inner cylinder 1, and the heat-conducting medium is led out by the heat-conducting medium outlet 22.

[0081] A central high-voltage electrode 3 is disposed in each of the reaction tubes 14 of the inner cylinder 1.

[0082] The grounding electrode 4 is formed of a solid conductive material. The grounding electrode 4 is respectively arranged around the inner sidewall of each of the reaction tubes 14, or the grounding electrode 4 is formed in at least part of the sidewall of each of the reaction tubes 14.

[0083] A blocking medium 6 is disposed on at least a portion of the outer surface of the central high-voltage electrode 3, such that the blocking medium 6 is wrapped around the outer surface of the central high-voltage electrode 3, which at least partially extends into the inner cylinder 1.

[0084] In each of the reaction tubes 14, the blocking medium 6 is positioned such that the discharge area between the central high-voltage electrode and the grounding electrode is separated by the blocking medium, and the ratio between the distance L1 between the outer wall of the blocking medium 6 and the inner wall of the grounding electrode and the length L2 of the discharge area is: L1:L2 = 1:(0.5~6000), more preferably L1:L2 = 1:(2~3000).

[0085] In a preferred embodiment, in each of the reaction tubes 14, the ratio of the distance L1 between the outer wall of the barrier medium 6 and the inner wall of the grounding electrode 4 to the thickness D1 of the barrier medium 6 is: L1:D1 = (0.05~100):1; more preferably, L1:D1 = (0.1~30):1.

[0086] Preferably, the central high-voltage electrodes 3 in each of the reaction tubes 14 are connected in parallel with each other.

[0087] In a preferred embodiment, the reaction apparatus further includes a grounding wire 5, which is disposed on the outer side wall of the outer cylinder 2 and is electrically connected at one end to the grounding electrode 4 in each of the reaction tubes 14.

[0088] Preferably, the reactor inlet 11 is located at the upper part of the inner cylinder 1, and the product outlet is located at the lower part and / or bottom of the inner cylinder 1.

[0089] In a preferred embodiment, the product outlets include a gas product outlet 12 and a liquid product outlet 13, with the gas product outlet 12 located at the lower part of the inner cylinder 1 and the liquid product outlet 13 located at the bottom of the inner cylinder 1.

[0090] In a preferred embodiment, each of the reaction tubes 14 is of the same size.

[0091] Preferably, the gas product outlet 12 is located below all the discharge areas, and the ratio between the height H1 of the gas product outlet 12 relative to the bottom of the inner cylinder 1 and the length L2 of the discharge area is: H1:L2 = 1:(0.05~25000); preferably H1:L2 = 1:(0.1~10000); more preferably H1:L2 = 1:(0.5~1000).

[0092] Preferably, the heat transfer medium inlet 21 and the heat transfer medium outlet 22 are respectively located at the lower and upper parts of the outer cylinder 2.

[0093] The following provides another preferred embodiment of the high-throughput plasma reactor described above in this invention for the decomposition of hydrogen sulfide:

[0094] Nitrogen gas is introduced into the inner cylinder of the high-flux plasma reactor through the reactor inlet to purge air from the discharge region, and the gas is then drawn out from the product outlet. Simultaneously, a heat-conducting medium is introduced into the outer cylinder through the heat-conducting medium inlet, and the introduced medium is drawn out from the heat-conducting medium outlet. The temperature of the heat-conducting medium is maintained at the temperature required for the system reaction. Then, a feed gas containing hydrogen sulfide is introduced into the inner cylinder of the high-flux plasma reactor through the reactor inlet, filling each reaction tube. After the feed gas flow stabilizes, the high-voltage power supply is connected, and a plasma discharge field is formed between the central high-voltage electrode and the grounding electrode by adjusting the voltage and frequency. The hydrogen sulfide gas ionizes in the discharge region, decomposing into hydrogen gas and elemental sulfur. The elemental sulfur produced by the discharge flows slowly down the inner cylinder wall and out from the product outlet.

[0095] The high-throughput plasma reactor provided by this invention also has the following specific advantages:

[0096] (1) The high-throughput plasma reaction device uses a conductive solid material as a grounding electrode. Compared with a liquid grounding electrode, the structure of the high-throughput plasma reaction device provided by this invention makes the micro-discharge current generated by the discharge of this grounding electrode larger, which is more conducive to the discharge decomposition reaction of hydrogen sulfide molecules.

[0097] (2) The high-throughput plasma reaction device is equipped with a jacket structure on the outside of the grounding electrode. The temperature of the reaction device 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 blocking the reaction device, and ensuring that the discharge continues stably.

[0098] (3) The high-throughput plasma reaction device controls the ratio between the distance L1 between the outer wall of the barrier medium and the inner wall of the grounding electrode and the length L2 of the discharge region to be: L1:L2 = 1:(0.5~6000); more preferably L1:L2 = 1:(2~3000). With the structure of the reaction device, the conversion rate of hydrogen sulfide can be significantly improved and the decomposition energy consumption can be reduced.

[0099] The present invention will be described in detail below through embodiments. In the following embodiments, unless otherwise specified, all raw materials used are commercially available.

[0100] The thickness of the barrier medium is the same in the following examples and comparative examples.

[0101] In the following examples, the conversion rate of hydrogen sulfide is calculated using the following formula:

[0102] Hydrogen sulfide conversion rate % = (Number of moles of hydrogen sulfide converted / Initial number of moles of hydrogen sulfide) × 100%

[0103] In the following examples, the energy consumption for decomposing hydrogen sulfide was obtained by measuring with an oscilloscope and calculating using Lissajous figures.

[0104] The volume of the inner cylinder of the reaction device in Example 1 below is 1L. The volumes of the inner cylinders of the reaction devices in the other examples and comparative examples can be calculated based on the corresponding data.

[0105] Example 1

[0106] use Figure 1 The high-flux plasma reactor shown is used for the decomposition of hydrogen sulfide. The specific structure and structural parameters of the high-flux plasma reactor are as follows:

[0107] The reaction apparatus includes:

[0108] The inner cylinder is provided with a reactor inlet, a gas product outlet, and a liquid product outlet. The inner cylinder contains four reaction tubes arranged in parallel, with the top and bottom of each reaction tube connected to each other. This allows the raw material entering from the reactor inlet to enter each reaction tube, and allows the gaseous products generated in each reaction tube to be led out through the gas product outlet and the liquid products generated in each reaction tube to be led out through the liquid product outlet. The four reaction tubes are all the same size.

[0109] An outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively provided on the outer cylinder. The heat-conducting medium introduced through the heat-conducting medium inlet can be distributed between each of the reaction tubes in the inner cylinder, and the heat-conducting medium is led out through the heat-conducting medium outlet.

[0110] A central high-voltage electrode is disposed at the central axis of each of the reaction tubes. The material forming the central high-voltage electrode is a stainless steel metal rod. The central high-voltage electrodes in each reaction tube are connected in parallel.

[0111] Grounding electrodes are respectively arranged around the inner sidewall of each of the reaction tubes. The material forming the grounding electrodes is stainless steel foil, and in this embodiment, the lower edge of the central high-voltage electrode is flush with the lower edge of the grounding electrode.

[0112] A barrier medium is disposed on the outer surface of the portion of the central high-voltage electrode that extends into the reaction tube, and the upper edge of the barrier medium is higher than the upper edge of the grounding electrode. The material forming the barrier medium is hard glass.

[0113] In each reaction tube, the ratio of the distance L1 between the outer wall of the barrier medium and the inner wall of the grounding electrode to the length L2 of the discharge region is 1:1700.

[0114] 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 = 1:48;

[0115] The ratio between L1 and the thickness D1 of the blocking medium is: L1:D1 = 6:1;

[0116] In this embodiment, the mixed gas enters the inner cylinder of the reaction device from the upper part and exits from the gas product outlet located at the lower part of the inner cylinder of the reaction device. Elemental sulfur is exited from the liquid product outlet located at the bottom of the reaction device. In this embodiment, the heat-conducting medium is introduced from the lower part of the outer cylinder of the reaction device and exited from the upper part of the outer cylinder of the reaction device.

[0117] Operating procedures for high-flux plasma reactors:

[0118] Nitrogen gas is introduced into the inner cylinder of the plasma reactor through the reactor inlet to purge air from the discharge region, and the gas is drawn out from the gaseous product outlet and the liquid product outlet. Simultaneously, a heat-conducting medium (specifically dimethyl silicone oil) is introduced into the outer cylinder through the heat-conducting medium inlet, and the introduced heat-conducting medium is drawn out from the heat-conducting medium outlet, with the temperature of the heat-conducting medium maintained at 145°C.

[0119] Then, an H2S / Ar mixed gas, with an H2S volume fraction of 20%, is introduced into the inner cylinder of the high-flux plasma reactor through the reactor inlet. The gas flow rate is controlled to ensure an average residence time of 8.8 s in the discharge zone. After 30 minutes of introduction, an AC high-voltage power supply is connected. By adjusting the voltage and frequency, a plasma discharge field is formed between the central high-voltage electrode and the grounding electrode. The discharge conditions are: voltage 18.2 kV, frequency 3.3 kHz, and current 1.8 A. Hydrogen sulfide gas ionizes in the discharge zone, decomposing into hydrogen and elemental sulfur. The elemental sulfur produced during the discharge flows slowly down the inner cylinder wall and exits from the liquid product outlet. The gaseous product outlet after the reaction exits.

[0120] Results: In this embodiment, the H2S conversion rate was measured to be 73.5% after the hydrogen sulfide decomposition reaction continued for 20 minutes; and no abnormalities were observed after 100 hours of continuous discharge, with both the discharge state and H2S conversion rate remaining stable. Furthermore, the decomposition energy consumption in this embodiment was 13.8 eV / H2S molecule (the energy required to decompose one molecule of H2S is 13.8 eV).

[0121] Comparative Example 1

[0122] This comparative example uses a high-throughput low-temperature plasma reactor similar to that in Example 1 for the hydrogen sulfide decomposition reaction, except that:

[0123] In this comparative example, the grounding electrode is a liquid grounding electrode, which is a molten LiCl and AlCl3 in a molar ratio of 1:1. This liquid grounding electrode is also a heat-conducting medium, maintaining a temperature of 145°C, and is placed in the outer cylinder of the reactor.

[0124] The gas flow rate was controlled so that the average residence time of the gas in the discharge region was 19.2 s.

[0125] Everything else is the same as in Example 1.

[0126] Furthermore, this comparative example uses the same operating method as Example 1 to carry out the hydrogen sulfide decomposition reaction.

[0127] Results: In this comparative example, the H2S conversion rate was 15.6% after the hydrogen sulfide decomposition reaction was carried out for 20 min. After continuous discharge for 1.5 h, the H2S conversion rate decreased to 5.1%.

[0128] The decomposition energy consumption in this comparative example is 115 eV / H2S molecule.

[0129] Comparative Example 2

[0130] This comparative example uses a low-temperature plasma reactor similar to that of Comparative Example 1, except that:

[0131] In each reaction tube, the ratio of L1 to the length L2 of the discharge region in this comparative example is 1:6500.

[0132] The gas flow rate was controlled so that the average residence time of the gas in the discharge region was 19.2 s.

[0133] The rest is the same as in Comparative Example 1.

[0134] Results: In this comparative example, the H2S conversion rate was 4.8% after the hydrogen sulfide decomposition reaction was carried out for 20 min. After continuous discharge for 1.5 h, the H2S conversion rate decreased to 1.4%.

[0135] The decomposition energy consumption in this comparative example is 140 eV / H2S molecule.

[0136] Example 2

[0137] This embodiment uses a high-throughput low-temperature plasma reactor similar to that in Example 1 to carry out the decomposition reaction of hydrogen sulfide. The difference is that in this embodiment:

[0138] The entire sidewall of the reaction tube is formed by grounding electrodes, and the material forming the grounding electrodes is stainless steel foil;

[0139] In each reaction tube, the ratio of the distance L1 between the outer wall of the barrier medium and the inner wall of the grounding electrode to the length L2 of the discharge region is 1:3000.

[0140] 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 = 1:250;

[0141] The ratio between L1 and the thickness D1 of the blocking medium is: L1:D1 = 15:1;

[0142] In this embodiment, an H2S / Ar mixed gas, with an H2S volume fraction of 20%, is introduced into the inner cylinder of the high-flux cryogenic plasma reactor from the reactor inlet. The gas flow rate is controlled to ensure an average residence time of 7.8 s in the discharge zone. After the H2S / Ar mixed gas has been introduced into the reactor for 30 minutes, an AC high-voltage power supply is connected. By adjusting the voltage and frequency, a plasma discharge field is formed between the central high-voltage electrode and the grounding electrode. The discharge conditions are: voltage 21.3 kV, frequency 0.9 kHz, and current 2.3 A.

[0143] The rest is the same as in Example 1.

[0144] Results: In this embodiment, the H2S conversion rate was measured to be 72.7% after the hydrogen sulfide decomposition reaction continued for 20 minutes; and no abnormalities were observed after 100 hours of continuous discharge, with both the discharge state and H2S conversion rate remaining stable. Furthermore, the decomposition energy consumption in this embodiment was 14.0 eV / H2S molecule.

[0145] Example 3

[0146] This embodiment uses a high-throughput low-temperature plasma reactor similar to that in Example 1 to carry out the decomposition reaction of hydrogen sulfide. The difference is that in this embodiment:

[0147] The entire sidewall of the reaction tube is formed by grounding electrodes, and the material forming the grounding electrodes is copper foil;

[0148] In each reaction tube, the ratio of the distance L1 between the outer wall of the barrier medium and the inner wall of the grounding electrode to the length L2 of the discharge region is 1:300.

[0149] 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 = 1:100;

[0150] The ratio between L1 and the thickness D1 of the blocking medium is: L1:D1 = 0.5:1;

[0151] In this embodiment, an H2S / Ar mixed gas, with an H2S volume fraction of 20%, is introduced into the inner cylinder of the high-flux cryogenic plasma reactor from the reactor inlet. The gas flow rate is controlled to ensure an average residence time of 10.5 s in the discharge zone. After the H2S / Ar mixed gas has been introduced into the reactor for 30 minutes, an AC high-voltage power supply is connected. By adjusting the voltage and frequency, a plasma discharge field is formed between the central high-voltage electrode and the grounding electrode. The discharge conditions are: voltage 13.7 kV, frequency 4.2 kHz, and current 2.5 A.

[0152] The rest is the same as in Example 1.

[0153] Results: In this embodiment, the H2S conversion rate was measured to be 74.2% after the hydrogen sulfide decomposition reaction continued for 20 minutes; and no abnormalities were observed after 100 hours of continuous discharge, with both the discharge state and H2S conversion rate remaining stable. Furthermore, the decomposition energy consumption in this embodiment was 14.3 eV / H2S molecule.

[0154] Example 4

[0155] This embodiment uses a plasma reactor similar to that in Example 1 to carry out the decomposition reaction of hydrogen sulfide. The difference is that in this embodiment:

[0156] The ratio of L1 to the thickness D1 of the blocking medium is 37:1.

[0157] The rest is the same as in Example 1.

[0158] Results: In this embodiment, the H2S conversion rate was measured to be 66.6% after the hydrogen sulfide decomposition reaction continued for 20 minutes; and no abnormalities were observed after 100 hours of continuous discharge, with both the discharge state and H2S conversion rate remaining stable. Furthermore, the decomposition energy consumption in this embodiment was 24.1 eV / H2S molecule.

[0159] Example 5

[0160] This embodiment uses a plasma reactor similar to that in Example 2 to carry out the decomposition reaction of hydrogen sulfide. The difference is that in this embodiment:

[0161] The ratio of L1 to the length L2 of the discharge region is 1:3500;

[0162] The rest is the same as in Example 2.

[0163] Results: In this embodiment, the H2S conversion rate was measured to be 65.8% after the hydrogen sulfide decomposition reaction continued for 20 minutes; and no abnormalities were observed after 100 hours of continuous discharge, with both the discharge state and H2S conversion rate remaining stable. Furthermore, the decomposition energy consumption in this embodiment was 23.7 eV / H2S molecule.

[0164] The results above show that when using the high-throughput plasma reaction device provided by the present invention to decompose hydrogen sulfide, the conversion rate of hydrogen sulfide can be significantly improved compared with the prior art, and the reaction device provided by the present invention can maintain a high hydrogen sulfide conversion rate for a long period of time with low decomposition energy consumption.

[0165] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A high-throughput plasma reactor, the reactor having a jacketed structure, and the reactor comprising: The inner cylinder (1) is provided with a reactor inlet (11) and a product outlet (13). The inner cylinder (1) contains at least two parallel reaction tubes (14), with the top and bottom of each reaction tube (14) communicating with each other, so that the raw material entering from the reactor inlet (11) can enter each of the reaction tubes (14) respectively, and the product generated in each of the reaction tubes (14) can be led out from the product outlet. The outer cylinder (2) is nested outside the inner cylinder (1), and the outer cylinder (2) is provided with a heat-conducting medium inlet (21) and a heat-conducting medium outlet (22). The heat-conducting medium introduced by the heat-conducting medium inlet (21) can be distributed between each of the reaction tubes (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) is disposed in each of the reaction tubes (14) of the inner cylinder (1); The grounding electrode (4) is formed of a solid conductive material. The grounding electrode (4) is respectively arranged around the inner sidewall of each of the reaction tubes (14), or the grounding electrode (4) is formed on at least part of the sidewall of each of the reaction tubes (14). A blocking medium (6) is disposed on at least a portion of the outer surface of the central high-voltage electrode (3), such that the outer surface of the central high-voltage electrode (3), which extends at least partially into the inner cylinder (1), is covered with the blocking medium (6). In each of the reaction tubes (14), the blocking medium (6) is positioned such that the discharge area between the central high-voltage electrode and the ground electrode is separated by the blocking medium, and the ratio between the distance L1 between the outer sidewall of the blocking medium (6) and the inner sidewall of the ground electrode and the length L2 of the discharge area is: L1:L2=1:(300~3000). The ratio between the distance L1 between the outer wall of the blocking medium (6) and the inner wall of the grounding electrode and the thickness D1 of the blocking medium is: L1:D1 = (0.5~15):1; The reactor inlet (11) is located at the upper part of the inner cylinder (1), and the product outlet is located at the lower part and bottom of the inner cylinder (1); The product outlets include a gas product outlet (12) and a liquid product outlet (13), with the gas product outlet (12) located at the lower part of the inner cylinder (1) and the liquid product outlet (13) located at the bottom of the inner cylinder (1). The gas product outlet (12) is located below all the discharge areas, and the ratio between the height H1 of the gas product outlet (12) relative to the bottom of the inner cylinder (1) and the length L2 of the discharge area is: H1:L2=1:(0.5~1000).

2. The high-throughput plasma reactor according to claim 1, wherein, The central high-voltage electrodes (3) in each of the reaction tubes (14) are connected in parallel to each other.

3. The high-throughput plasma reactor according to claim 1 or 2, wherein, The material forming the barrier medium is an electrically insulating material.

4. The high-throughput plasma reactor according to claim 3, wherein, The material forming the barrier medium is selected from at least one of glass, quartz, ceramic, enamel, polytetrafluoroethylene, and mica.

5. The high-throughput plasma reactor according to claim 1 or 2, wherein, The reaction device also includes a grounding wire (5), which is disposed on the outer wall of the outer cylinder (2) and one end is electrically connected to the grounding electrode (4) in each of the reaction tubes (14).

6. The high-throughput plasma reactor according to claim 1 or 2, wherein, Each of the aforementioned reaction tubes (14) has the same size.

7. The high-throughput plasma reactor according to claim 1 or 2, wherein, The heat-conducting medium inlet (21) and the heat-conducting medium outlet (22) are respectively located at the lower and upper parts of the outer cylinder (2).

8. The high-throughput plasma reactor according to claim 1, wherein, The material forming the grounding electrode (4) is selected from graphite tubes, metal tubes, metal foils or metal meshes.

9. The high-throughput plasma reactor according to claim 1, wherein, The material forming the central high-voltage electrode (3) is selected from at least one of graphite tube, metal rod, metal tube, graphite powder, metal powder and graphite rod.

10. A method for decomposing hydrogen sulfide, the method being carried out in the high-throughput plasma reactor according to any one of claims 1-9, the method comprising: Under dielectric barrier discharge conditions, a feed gas containing hydrogen sulfide is introduced from the reactor inlet into the reaction tube of the inner cylinder of the high-flux plasma reactor to carry out the decomposition reaction of hydrogen sulfide. The resulting stream is led out from the product outlet. The required temperature of the high-flux plasma reactor is maintained by continuously introducing a heat-conducting medium into the outer cylinder of the high-flux plasma reactor from the heat-conducting medium inlet and leading out the heat-conducting medium from the heat-conducting medium outlet. The dielectric barrier discharge is formed by the grounding electrode, the barrier medium, and the central high-voltage electrode in each of the reaction tubes.

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