Plasma device and method for decomposing hydrogen sulfide

Abstract

The present invention relates to the field of plasma chemistry, and discloses a plasma device and a method for decomposing hydrogen sulfide. The device comprises: a first cavity (1), a second cavity (2), an inner electrode (3), an outer electrode (4), and a blocking medium (6), wherein the inner electrode (3) and the outer electrode (4) are both solid electrodes, and the shapes of the two electrodes cooperate with each other to form an isodiameter structure. The low-temperature plasma reactor provided by the present invention can realize the continuous and stable decomposition process of hydrogen sulfide at a significantly higher hydrogen sulfide conversion rate, and the device can realize long-term operation.

Description

Technical Field

[0001] The invention relates to the field of plasma chemistry, and in particular to a plasma device and a method for decomposing hydrogen sulfide. Background Art

[0002] Hydrogen sulfide (H2S) is a highly toxic, foul-smelling acidic gas that not only causes corrosion of metals and other materials, but also harms human health and pollutes the environment. At present, large and medium-sized refineries in my country use the traditional Claus process to treat tail gas containing H2S and recover sulfur. This method only recovers the sulfur in hydrogen sulfide, but converts the precious hydrogen into water. From the perspective of comprehensive resource utilization, hydrogen resources have not been effectively utilized in traditional hydrogen sulfide recovery processes.

[0003] Therefore, decomposing hydrogen sulfide into sulfur and hydrogen has gradually become a technical field that domestic and foreign scientific researchers focus on.

[0004] At present, the methods for decomposing hydrogen sulfide mainly include: high-temperature decomposition method, electrochemical method, photocatalytic method and low-temperature plasma method. Among the above 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 thermodynamic equilibrium. Even if the reaction temperature is above 1000°C, the conversion rate of hydrogen sulfide is only 20%. In addition, high temperature conditions have high requirements for reactor materials, which will also increase 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 in the system, which also reduces the efficiency of the device and increases energy consumption, all of which bring difficulties to its large-scale industrial application. Although the use of membrane technology can effectively separate products to break the equilibrium limit and improve the conversion rate of hydrogen sulfide, the thermal decomposition temperature often exceeds the extreme heat resistance temperature of the membrane, causing the membrane material structure to be destroyed. The electrochemical method has the disadvantages of many operating steps, severe equipment corrosion, poor reaction stability and low efficiency. The photocatalytic decomposition of hydrogen sulfide mainly draws on the research on photocatalytic decomposition of water, and the research focus is on the development of efficient semiconductor photocatalysts. Using solar energy to decompose hydrogen sulfide is a relatively economical method with the advantages of low energy consumption, mild reaction conditions, and simple operation. However, this method has problems such as small processing capacity, low catalytic efficiency, and easy deactivation of the catalyst.

[0005] Compared with other decomposition methods, the low-temperature plasma method has the advantages of simple operation, small device size, high energy efficiency, etc., and the reactions involved are highly controllable and can be flexibly applied in small processing volumes and where centralized processing is difficult. In addition, due to its high energy density and shortened reaction time, it can effectively decompose hydrogen sulfide at a relatively low temperature, which is suitable for occasions of different scales, dispersed layouts, and variable production conditions. Moreover, while recovering sulfur, the low-temperature plasma method recovers hydrogen resources, which can realize the resource utilization of hydrogen sulfide.

[0006] At present, researchers at home and abroad have conducted extensive research on the technology of low-temperature plasma decomposition of hydrogen sulfide. The discharge forms used mainly include glow discharge, corona discharge, sliding arc discharge, microwave plasma, radio frequency plasma and dielectric barrier discharge.

[0007] CN102408095A uses dielectric barrier discharge and photocatalyst to synergistically decompose hydrogen sulfide, and its method is to fill a solid catalyst with photocatalytic activity in a plasma region. However, this method has the disadvantage that sulfur produced by the decomposition of hydrogen sulfide will be deposited under the catalyst bed.

[0008] CN103204466A discloses a temperature-controlled hydrogen sulfide decomposition device and method, the characteristics of which are that the central electrode is metal, the ground electrode is a temperature-controllable circulating liquid, and the temperature of the liquid ground electrode is controlled, so that the hydrogen sulfide decomposition process can be carried out continuously and stably. In addition, CN103204467A discloses a device and method for producing hydrogen by continuously and stably decomposing hydrogen sulfide. The characteristics of this prior art are that the central electrode is metal, the ground electrode is a temperature-controllable circulating liquid, the temperature is controlled by the liquid ground electrode, the raw material intake direction is circumferential intake, and it passes through the discharge zone in a spiral mode in the axial direction in reverse, so that the generated sulfur is centrifugally separated in time. However, in order to ensure that hydrogen sulfide is decomposed as fully as possible in the methods disclosed in CN103204466A and CN103204467A, it is necessary to control the flow rate of hydrogen sulfide so that its residence time in the inner cylinder of the reactor is longer and to control the size of the inner cylinder so that more electric energy is obtained per unit volume of gas in the inner cylinder. Moreover, since the current prior art cannot provide a power source with higher power, the methods disclosed in CN103204466A and CN103204467A can only achieve a maximum conversion rate of hydrogen sulfide of about 20% even if the residence time of hydrogen sulfide is controlled to be longer and the size of the inner cylinder is controlled so that more electric energy is obtained per unit volume of gas in the inner cylinder. 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 also have the defect that there are very few types of liquid grounding electrodes that can be used. The salt solutions disclosed therein can generally 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 blockage of the reactor. Summary of the invention

[0009] The purpose of the present invention is to overcome the defects of low hydrogen sulfide conversion rate and high decomposition energy consumption in the low-temperature plasma reaction equipment provided by the prior art when used for decomposing hydrogen sulfide, and to provide a new low-temperature plasma reaction equipment capable of improving the hydrogen sulfide conversion rate and reducing the decomposition energy consumption, and a method for decomposing hydrogen sulfide using the reaction equipment.

[0010] The difference between the "side wall" and the "outer wall" and "inner wall" of the present invention is that the "outer wall" and "inner wall" respectively represent the outer surface and inner surface of the "side wall", and if it is a "side wall", it means the "outer wall" and / or "inner wall".

[0011] In order to achieve the above object, in a first aspect, the present invention provides a plasma reaction device, the reaction device comprising:

[0012] A first cavity, wherein a first inlet and a first outlet are respectively provided on the first cavity;

[0013] A second cavity, wherein the second cavity is nested inside the first cavity, and a second inlet and a second outlet are respectively provided on the second cavity;

[0014] an inner electrode, at least a portion of which extends into the first cavity;

[0015] an outer electrode, the outer electrode forming at least a portion of a side wall of the first cavity or being disposed around an outer side wall of the first cavity; and

[0016] a blocking medium, forming at least a part of the side wall of the first cavity or surrounding the inner side wall of the first cavity, and the blocking medium is arranged between the inner electrode and the outer electrode, so that the discharge area between the inner electrode and the outer electrode is separated by the blocking medium;

[0017] The inner electrode and the outer electrode are both solid electrodes, and their shapes match each other to form an equal-diameter structure;

[0018] The distance between the outer wall of the inner electrode and the inner wall of the outer electrode is L1, the thickness of the blocking medium is D1, L2=L1-D1, and the ratio between L2 and D1 is (0.1-100):1.

[0019] The “equal diameter structure” means a structure in which the minimum distance between any point on the outer wall of the inner electrode and the inner wall of the outer electrode is equal to the minimum distance between other points on the outer wall of the inner electrode and the inner wall of the outer electrode.

[0020] Preferably, the ratio between L2 and D1 is (0.1-30):1; more preferably (0.2-15):1.

[0021] According to a preferred embodiment, the inner electrode forms at least a portion of a side wall of the second cavity.

[0022] According to another preferred specific embodiment, the inner electrode is arranged on the outer side wall of the second cavity in a surrounding manner.

[0023] According to another preferred embodiment, the inner electrode is disposed around the inner side wall of the second cavity. In this preferred embodiment, the device preferably contains a double barrier medium, and the other barrier medium forms at least a part of the side wall of the second cavity, and D1 is the sum of the thickness of the barrier medium and the other barrier medium.

[0024] For the purpose of distinguishing description, the present invention refers to the blocking medium that forms at least a portion of the sidewall of the first cavity or surrounds the inner sidewall of the first cavity as "blocking medium"; and the blocking medium that forms at least a portion of the sidewall of the second cavity as "another blocking medium". The materials of the blocking medium of the present invention and the other blocking medium may be the same or different.

[0025] In the present invention, the shapes of the first cavity and the second cavity may be, for example, cylindrical, serpentine, fin-shaped, S-shaped, or wavy.

[0026] According to a preferred specific implementation manner, the outer electrode is disposed around the outer side wall of the first cavity, and the first cavity is formed by a blocking medium.

[0027] According to another preferred specific implementation manner, the outer electrode is disposed around the outer side wall of the first cavity, and the blocking medium forms at least a part of the side wall of the first cavity.

[0028] In the present invention, the inner electrode may be, for example, cylindrical, the first cavity is a hollow cylinder extending in an axial direction with equal diameter, and the inner electrode and the first cavity are coaxial.

[0029] The aforementioned low-temperature plasma reaction equipment provided by the present invention is preferably a jacketed dielectric barrier discharge reaction equipment with a coaxial structure, and its basic structure mainly includes an inner electrode, an outer electrode and a barrier medium, etc. The sleeve structure enables the heat-conducting medium to perform cyclic heating or cooling on the discharge reaction equipment, thereby realizing flexible temperature control of the discharge area. In particular, the present invention can significantly improve the conversion rate of hydrogen sulfide and reduce the decomposition energy consumption compared with the prior art by controlling the ratio of L2 to the thickness D1 of the barrier medium within a specific range, and applying a solid inner electrode and a solid outer electrode.

[0030] The jacket structure design of the present invention can make the heat-conducting medium circulate in the shell layer, and can maintain the entire reaction equipment within a certain temperature range while ensuring the discharge intensity, so that the generated sulfur flows out of the reaction equipment in liquid form, and can effectively avoid the solidification of sulfur generated by the decomposition of hydrogen sulfide. While achieving a higher conversion rate, this decomposition process can be continuous and stably realized for a long period of time.

[0031] Preferably, the number of the first cavity is one.

[0032] According to a preferred specific embodiment, the number of the first cavities is more than 2, and the inner electrode, the outer electrode and the blocking medium are respectively disposed in each of the first cavities. In this preferred specific embodiment, preferably, each of the inner electrodes is connected in parallel with each other. In this preferred specific embodiment, preferably, each of the outer electrodes is connected in parallel with each other.

[0033] Preferably, the material of the blocking medium and the other blocking medium is an electrical insulating material. More preferably, it is selected from at least one of glass, quartz, ceramic, enamel, polytetrafluoroethylene and mica. The glass may be quartz glass or hard glass; the material forming the blocking medium may also be other metal and non-metal composite materials with high voltage electrical insulation design. The ceramic may be alumina ceramic.

[0034] Preferably, the outer electrode and the inner electrode are conductive materials. Preferably, the outer electrode and the inner electrode can be independently selected from at least one of graphite tube, graphite powder, metal rod, metal foil, metal mesh, metal tube, metal powder and graphite rod.

[0035] The metal rod and metal tube may include a simple metal rod, an alloy metal rod, a simple metal tube, or an alloy metal tube. The metal powder may include a simple metal powder, an alloy metal powder, or a mechanical mixture of a simple metal powder and / or an alloy metal powder. The material forming the electrodes (including the inner electrode and the outer electrode) of the present invention may also be other rod-shaped and tubular materials having conductive properties.

[0036] In the present invention, preferably, one of the inner electrode and the outer electrode is a ground electrode, and the other is a high voltage electrode. Those skilled in the art can determine the materials of the inner electrode and the outer electrode according to application requirements.

[0037] Preferably, the reaction device of the present invention further comprises a grounding wire, one end of which is electrically connected to the outer electrode or the inner electrode.

[0038] Preferably, the first inlet is arranged at an upper portion of the first cavity, and the first outlet is arranged at a lower portion and / or a bottom of the first cavity.

[0039] Preferably, the first outlet includes a gas product outlet and a liquid product outlet, and the gas product outlet is arranged at the lower part of the first cavity, and the liquid product outlet is arranged at the bottom of the first cavity.

[0040] Preferably, the gas product outlet is arranged below the discharge area, and the proportional relationship between the height H1 of the setting position of the gas product outlet relative to the bottom of the first cavity and the length L3 of the discharge area is: H1:L3=1:(0.05~25000); preferably H1:L3=1:(0.1~10000); more preferably H1:L3=1:(0.5~1000).

[0041] In the present invention, the “discharge region” refers to a region where the inner electrode, the outer electrode and the barrier medium completely overlap.

[0042] In the present invention, the ratio of the inner diameter of the first cavity to the aperture of the first outlet may be (0.1-100):1.

[0043] In the present invention, the ratio of the aperture of the first inlet to the aperture of the first outlet may be (0.1-120):1.

[0044] The ratio between the length of the first cavity and the inner diameter of the first cavity of the present invention may be (0.5-500): 1. The inner diameter of the first cavity refers to the distance from the axial core of the first cavity to the outer side wall of the first cavity.

[0045] Preferably, the second inlet and the second outlet are respectively arranged at a lower portion and an upper portion of the second cavity.

[0046] The first inlet of the present invention may be arranged so that the raw material gas entering the first cavity is parallel to or at a certain angle to the inner diameter of the first cavity, for example, it may be arranged tangentially.

[0047] The present invention can maintain the temperature of the reaction device with a jacket structure at, for example, 119-444.6° C. by introducing a heat-conducting medium into the second cavity. In this case, the generated sulfur can continuously flow out in liquid form.

[0048] The low-temperature plasma reaction device of the present invention may also be loaded with a catalyst capable of catalyzing the decomposition of hydrogen sulfide into elemental sulfur and hydrogen, and the catalyst is preferably loaded in the first cavity of the reaction device. The present invention has no special requirements on the loading volume and loading type of the catalyst. Regarding the type of catalyst, for example, it can be any one or more of the catalysts disclosed in CN102408095A, CN101590410A and CN103495427A.

[0049] The aforementioned low-temperature plasma reaction equipment provided by the present invention can be used for plasma decomposition of hydrogen sulfide. The reaction equipment can generate uniform and efficient dielectric barrier discharge, thereby directly decomposing hydrogen sulfide into hydrogen and sulfur.

[0050] In a second aspect, the present invention provides a method for decomposing hydrogen sulfide, which is implemented in the low-temperature plasma reaction equipment described in the first aspect of the present invention, and the method comprises: connecting one of the outer electrode and the inner electrode of the low-temperature plasma reaction equipment to a high voltage power supply and grounding the other to perform dielectric barrier discharge, introducing a raw gas containing hydrogen sulfide into the first cavity from a first inlet of a first cavity of the low-temperature plasma reaction equipment to perform a decomposition reaction of hydrogen sulfide, and leading out a stream obtained after decomposition from a first outlet, and continuously introducing a heat-conducting medium into the second cavity of the low-temperature plasma reaction equipment from a second inlet and leading out the heat-conducting medium from a second outlet to control the temperature of the first cavity of the low-temperature plasma reaction equipment.

[0051] Preferably, the conditions of the dielectric barrier discharge include: a discharge voltage of 2 kV to 80 kV, preferably 5 kV to 30 kV, more preferably 5 kV to 20 kV, and even more preferably 5 kV to 15 kV; a discharge frequency of 200 to 30,000 Hz, preferably 500 to 15,000 Hz, and even more preferably 500 to 13,000 Hz.

[0052] Preferably, the conditions of the decomposition reaction include: a reaction temperature of 0 to 800° C., preferably 40 to 500° C., more preferably 119 to 444.6° C.; and a reaction pressure of 0 to 0.6 MPa, preferably 0 to 0.3 MPa.

[0053] Preferably, the residence time of the raw gas containing hydrogen sulfide in the discharge region of the low-temperature plasma reaction device is 1×10 -5 ~120s, preferably 2×10 -5 ~60s.

[0054] Preferably, the decomposition reaction of hydrogen sulfide is carried out in the presence of a carrier gas, and the carrier gas is selected from at least one of nitrogen, hydrogen, helium, argon, water vapor, carbon monoxide, carbon dioxide, methane, ethane and propane; more preferably, the carrier gas is selected from at least one of hydrogen, argon, helium and nitrogen.

[0055] Particularly preferably, the carrier gas is selected from at least one of hydrogen, argon, helium and nitrogen.

[0056] Preferably, the content of hydrogen sulfide gas in the raw gas is such that the content of hydrogen sulfide gas at the first inlet of the low-temperature plasma reaction device is 1*10 -8 ~100% volume %; more preferably 10~100% volume %.

[0057] In the present invention, the raw gas does not include the aforementioned carrier gas of the present invention. The raw gas is pure hydrogen sulfide gas or industrial waste gas obtained in industrial production containing hydrogen sulfide and other gases. Although the raw gas may contain the same type of gas as the carrier gas defined in the present invention, the carrier gas defined in the present invention is a gas that is actively added to mix with the raw gas, and the method of the present invention can control the amount of carrier gas added as needed.

[0058] The following provides a preferred specific implementation method for decomposing hydrogen sulfide using the aforementioned low-temperature plasma reaction equipment of the present invention:

[0059] A protective gas such as nitrogen is introduced into the first cavity of the low-temperature plasma reaction device from the first inlet to remove the air in the discharge area, and the gas is drawn out from the first outlet. At the same time, a heat-conducting medium is introduced into the second cavity from the second inlet, and the introduced heat-conducting medium is drawn out from the second outlet. The temperature of the heat-conducting medium is maintained at the temperature required for the system reaction. Then, a raw gas containing hydrogen sulfide is introduced into the first cavity of the low-temperature plasma reaction device from the first inlet, and a high-voltage power supply is connected after the raw gas flow is stable, and a plasma discharge field is formed between the inner electrode and the outer electrode by adjusting the voltage and frequency. The hydrogen sulfide gas is ionized in the discharge area and decomposed into hydrogen and elemental sulfur. The elemental sulfur generated by the discharge slowly flows down along the wall of the first cavity and flows out from the first outlet.

[0060] The low-temperature plasma reaction equipment provided by the present invention can realize the continuous and stable decomposition process of hydrogen sulfide at a significantly higher hydrogen sulfide conversion rate, and the device can realize long-term operation.

[0061] Furthermore, the low-temperature plasma reaction equipment provided by the present invention can also be used in large-flow, high-concentration hydrogen sulfide treatment processes. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 It is a structural schematic diagram of a preferred specific implementation of the low-temperature plasma reaction equipment provided by the present invention.

[0063] Description of Reference Numerals

[0064] 1. First cavity 2. Second cavity

[0065] 11. First entrance 21. Second entrance

[0066] 12. Gas product outlet 22. Second outlet

[0067] 13. Liquid product export

[0068] 3. Inner electrode

[0069] 4. External electrode

[0070] 5. Ground wire

[0071] 6. Barrier medium DETAILED DESCRIPTION

[0072] The endpoints and any values ​​of the ranges disclosed in this article 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 each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0073] The following combination Figure 1 The structure of a preferred embodiment of the low temperature plasma reaction device of the present invention is provided, specifically:

[0074] The reaction device has a coaxial sleeve structure, and the reaction device comprises:

[0075] A first cavity 1, wherein a first inlet 11 and a first outlet are respectively provided on the first cavity 1;

[0076] A second cavity 2, wherein the second cavity 2 is nested inside the first cavity 1, and a second inlet 21 and a second outlet 22 are respectively provided on the second cavity 2;

[0077] an internal electrode 3, wherein the internal electrode 3 is arranged in the first cavity 1;

[0078] The outer electrode 4 forms at least a part of the side wall of the first cavity 1 or is arranged around the outer side wall of the first cavity 1; and

[0079] A blocking medium, the blocking medium forming at least a part of the side wall of the first cavity 1 or surroundingly arranged on the inner side wall of the first cavity 1, and the blocking medium being arranged between the inner electrode 3 and the outer electrode 4, so that the discharge region between the inner electrode and the outer electrode is separated by the blocking medium;

[0080] The inner electrode 3 and the outer electrode 4 are both solid electrodes, and their shapes match each other to form an equal-diameter structure;

[0081] The distance between the outer wall of the inner electrode 3 and the inner wall of the outer electrode 4 is L1, the thickness of the blocking medium 6 is D1, L2=L1-D1, and the ratio between L2 and D1 is (0.1~100):1, preferably the ratio between L2 and D1 is (0.1~30):1; more preferably (0.2~15):1.

[0082] Preferably, the internal electrode 3 forms at least a portion of a side wall of the second cavity 2 .

[0083] According to a preferred specific implementation manner, the inner electrode 3 is arranged around the outer side wall of the second cavity 2 .

[0084] According to a preferred embodiment, the inner electrode 3 is disposed around the inner wall of the second cavity 2. In the preferred embodiment, the device preferably contains a double barrier medium, and another barrier medium (not shown in the figure) forms at least part of the side wall of the second cavity 2, and D1 is the sum of the thickness of the barrier medium 6 and the other barrier medium.

[0085] Preferably, the outer electrode 4 is disposed around the outer side wall of the first cavity 1 , and the first cavity 1 is formed by a blocking medium 6 .

[0086] Preferably, the outer electrode 4 is disposed around the outer side wall of the first cavity 1 , and the blocking medium forms at least a portion of the side wall of the first cavity 1 .

[0087] Preferably, the number of the first cavity 1 is one.

[0088] According to another preferred embodiment, the number of the first cavities 1 is more than 2, and the inner electrode 3, the outer electrode 4 and the blocking medium 6 are respectively disposed in each of the first cavities 1. In this preferred embodiment, the inner electrodes 3 are preferably connected in parallel to each other; and the outer electrodes 4 are preferably connected in parallel to each other.

[0089] Preferably, the reaction device further comprises a grounding wire 5 , one end of which is electrically connected to the inner electrode 3 or the outer electrode 4 .

[0090] In the present invention, one of the inner electrode 3 and the outer electrode 4 is a ground electrode, and the other is a high voltage electrode.

[0091] Preferably, the first inlet 11 is arranged at an upper portion of the first cavity 1 , and the first outlet is arranged at a lower portion and / or a bottom portion of the first cavity 1 .

[0092] Preferably, the second inlet 21 and the second outlet 22 are respectively disposed at the lower part and the upper part of the second cavity 2 .

[0093] Preferably, the first outlet includes a gas product outlet 12 and a liquid product outlet 13 , and the gas product outlet 12 is disposed at the lower portion of the first cavity 1 , and the liquid product outlet 13 is disposed at the bottom of the first cavity 1 .

[0094] Preferably, the gas product outlet 12 is arranged below the discharge area, and the proportional relationship between the height H1 of the setting position of the gas product outlet 12 relative to the bottom of the first cavity 1 and the length L3 of the discharge area is: H1:L3=1:(0.05~25000); preferably H1:L3=1:(0.1~10000); more preferably H1:L3=1:(0.5~1000).

[0095] Unless otherwise specified, the pressure in the present invention refers to absolute pressure.

[0096] The low-temperature plasma reaction equipment provided by the present invention also has the following specific advantages:

[0097] (1) The reaction equipment uses a conductive solid material as a grounding electrode for grounding. Compared with a liquid grounding electrode, the micro-discharge current generated by the discharge of this solid grounding electrode in combination with the structure of the present invention is larger, which is more conducive to the discharge decomposition reaction of hydrogen sulfide molecules.

[0098] (2) The reaction equipment is provided with a jacket structure, and the temperature of the reaction equipment can be controlled by controlling the temperature of the heat-conducting medium in the jacket, so that the sulfur produced by the discharge decomposition of hydrogen sulfide can flow out of the discharge area smoothly, avoiding the sulfur solidification and clogging the reaction equipment, so that the discharge can be carried out continuously and stably.

[0099] (3) The reaction device controls the ratio of L2 to the thickness D1 of the blocking medium to be (0.1-100):1, preferably (0.1-30):1, and more preferably (0.2-15):1. In combination with the other structures of the reaction device of the present invention, the conversion rate of hydrogen sulfide can be significantly improved and the decomposition energy consumption can be reduced.

[0100] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all the raw materials used are commercially available.

[0101] The thickness of the barrier media in the following examples and comparative examples is the same.

[0102] The conversion rate of hydrogen sulfide in the following examples is calculated according to the following formula:

[0103] Decomposition rate of hydrogen sulfide % = number of moles of converted hydrogen sulfide / number of moles of initial hydrogen sulfide × 100%

[0104] In the following examples, the energy consumption for decomposing hydrogen sulfide is measured by an oscilloscope and calculated using Lissajous figures.

[0105] Unless otherwise specified, the following inner electrodes are all high voltage electrodes and the outer electrodes are all solid grounding electrodes.

[0106] Example 1

[0107] use Figure 1 The low-temperature plasma reaction device shown in the figure performs a hydrogen sulfide decomposition reaction. The specific structure and structural parameters of the low-temperature plasma reaction device are as follows. The inner electrode of this embodiment is a high-voltage electrode:

[0108] The reaction equipment includes:

[0109] A first cavity, wherein a first inlet, a gas product outlet and a liquid product outlet are respectively provided on the first cavity, wherein all side walls of the first cavity are formed by a barrier medium, and the material forming the barrier medium is hard glass;

[0110] A second cavity, wherein the second cavity is nested inside the first cavity, and a second inlet and a second outlet are respectively provided on the second cavity;

[0111] An inner electrode, the inner electrode forms a side wall of the second cavity, the inner electrode is made of stainless steel, and the inner electrode is connected to a high voltage power supply;

[0112] An outer electrode, the outer electrode is wrapped on the outer side wall of the first cavity, the material forming the outer electrode is a stainless steel metal foil, and the outer electrode is grounded; and the lower edge of the inner electrode in this embodiment is lower than the lower edge of the solid grounding electrode;

[0113] The ratio of L2 to the thickness D1 of the barrier medium is 4:1; and H1:L3=1:100;

[0114] The volume of the first cavity of the reaction device in this embodiment is 0.2L.

[0115] In this embodiment, the mixed gas enters the first cavity of the reaction equipment from the upper part of the first cavity of the reaction equipment, and the gas product is drawn out from the gas product outlet located at the lower part of the first cavity of the reaction equipment, and the elemental sulfur is drawn out from the liquid product outlet located at the bottom of the reaction equipment; and the heat transfer medium of this embodiment is introduced from the lower part of the second cavity of the reaction equipment and drawn out from the upper part of the second cavity of the reaction equipment.

[0116] Operation steps of low temperature plasma reaction equipment:

[0117] Nitrogen is introduced into the first cavity of the low-temperature plasma reaction device from the first inlet to remove the air in the discharge area, and the gas is led out from the gas product outlet and the liquid product outlet. At the same time, a heat-conducting medium (specifically dimethyl silicone oil) is introduced into the second cavity from the second inlet, and the introduced heat-conducting medium is led out from the second outlet, and the temperature of the heat-conducting medium is maintained at 145°C.

[0118] Then, a H2S / Ar mixed gas is introduced into the first cavity of the low-temperature plasma reaction equipment from the first inlet, wherein the volume fraction of H2S is 30%, and the mixed gas flow rate is controlled so that the average residence time of the gas in the discharge zone is 16.7s. In this embodiment, the reaction pressure in the first cavity of the reactor is maintained at 0.12MPa. After the H2S / Ar mixed gas is introduced into the reaction equipment for 30 minutes, an AC high-voltage power supply is turned on, and a plasma discharge field is formed between the inner electrode and the solid ground electrode by adjusting the voltage and frequency. The discharge conditions are as follows: the voltage is 16.3kV, the frequency is 1.2kHz, and the current is 1.05A. The hydrogen sulfide gas is ionized in the discharge area and decomposed into hydrogen and elemental sulfur. The elemental sulfur produced by the discharge slowly flows down the wall of the first cavity, and the liquid product is released intermittently. The gas after the reaction flows out from the gas product outlet.

[0119] Results: After the hydrogen sulfide decomposition reaction of this embodiment was continued for 20 minutes, the H2S conversion rate was measured to be 78.7%; and no abnormality was found after continuous discharge for 100 hours, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this embodiment was 12.8eV / H2S molecule (the energy consumed for decomposing one molecule of H2S was 12.8eV).

[0120] Comparative Example 1

[0121] This comparative example uses a low-temperature plasma reaction device similar to that of Example 1 to carry out the hydrogen sulfide decomposition reaction, except that:

[0122] The ground electrode in this comparative example is a liquid ground electrode, and is a molten state of LiCl and AlCl3 with a molar ratio of 1:1. The liquid ground electrode is also a heat-conducting medium, maintained at a temperature of 145°C, and placed in the second cavity of the reaction device. The outer electrode in this comparative example is arranged around the outer side wall of the first cavity, and the outer electrode is connected to a high-voltage power supply.

[0123] The mixed gas flow rate is controlled so that the average residence time of the gas in the discharge zone is 23.7s.

[0124] The volume of the first cavity of the reaction device of this comparative example is 0.05L.

[0125] The rest are the same as in Example 1.

[0126] In this comparative example, the same operation method as in Example 1 was used to carry out the hydrogen sulfide decomposition reaction.

[0127] Results: After the hydrogen sulfide decomposition reaction of this comparative example was continued for 20 minutes, the H2S conversion rate was measured to be 17.9%. After continuous discharge for 1.5 hours, the H2S conversion rate decreased to 6.6%.

[0128] The decomposition energy consumption of this comparative example is 124 eV / H2S molecule.

[0129] Comparative Example 2

[0130] This comparative example is carried out using a low-temperature plasma reaction equipment similar to that of comparative example 1, except that:

[0131] In this comparative example, the ratio of L2 to the thickness D1 of the blocking medium is 0.08:1.

[0132] The mixed gas flow rate is controlled so that the average residence time of the gas in the discharge zone is 21.4s.

[0133] The volume of the first cavity of this comparative example is 0.02L.

[0134] The rest are the same as in Comparative Example 1.

[0135] Results: After the hydrogen sulfide decomposition reaction of this comparative example was continued for 20 minutes, the H2S conversion rate was measured to be 25.4%. After continuous discharge for 1.5 hours, the H2S conversion rate decreased to 6.9%.

[0136] The decomposition energy consumption of this comparative example is 132 eV / H2S molecule.

[0137] Example 2

[0138] This embodiment uses a plasma reaction device similar to that of Embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, except that in this embodiment:

[0139] The side wall of the first cavity is used as an external electrode, and the external electrode is connected to a high-voltage power supply, so that the side wall of the first cavity serves as a high-voltage electrode, and the material forming the external electrode is stainless steel metal foil; and the side wall of the second cavity is grounded as an internal electrode, so that the side wall of the second cavity serves as a grounding electrode.

[0140] The blocking medium is disposed around the inner wall of the first cavity;

[0141] The ratio of L2 to the thickness D1 of the blocking medium is 6:1; and H1:L3=1:46.

[0142] In this embodiment, a H2S / Ar mixed gas is introduced from the first inlet into the first cavity of the low-temperature plasma reaction device, wherein the volume fraction of H2S is 30%, and the mixed gas flow rate is controlled so that the average residence time of the gas in the discharge zone is 6.4s. In this embodiment, the reaction pressure in the first cavity of the reactor is maintained at 0.05MPa. After the H2S / Ar mixed gas is introduced into the reaction device for 30 minutes, an AC high-voltage power supply is turned on, and a plasma discharge field is formed between the inner electrode and the solid ground electrode by adjusting the voltage and frequency. The discharge conditions are: voltage of 17.5kV, frequency of 7.8kHz, and current of 1.14A.

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

[0144] Results: After the hydrogen sulfide decomposition reaction of this embodiment was continued for 20 minutes, the H2S conversion rate was measured to be 78.5%; and no abnormality was found after continuous discharge for 100 hours, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this embodiment was 13.1eV / H2S molecule.

[0145] Example 3

[0146] This embodiment uses a plasma reaction device similar to that of Embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, except that in this embodiment:

[0147] All side walls of the first cavity are formed by external electrodes, the material forming the external electrodes is copper foil, the external electrodes are grounded, and the internal electrodes are connected to a high voltage power supply;

[0148] The blocking medium is disposed around the inner wall of the first cavity;

[0149] The ratio of L2 to the thickness D1 of the blocking medium is 0.5:1; and H1:L3=1:200.

[0150] In this embodiment, H2S / Ar mixed gas is introduced into the first cavity of the low-temperature plasma reaction device from the first inlet, wherein the volume fraction of H2S is 25%, and the mixed gas flow rate is controlled so that the average residence time of the gas in the discharge zone is 3.4s. In this embodiment, the reaction pressure in the first cavity of the reactor is maintained at 0.27MPa. After the H2S / Ar mixed gas is introduced into the reaction device for 30 minutes, an AC high-voltage power supply is turned on, and a plasma discharge field is formed between the inner electrode and the solid ground electrode by adjusting the voltage and frequency. The discharge conditions are: voltage of 19.7kV, frequency of 12.7kHz, and current of 0.97A.

[0151] The rest are the same as in Example 1.

[0152] Results: After the hydrogen sulfide decomposition reaction of this embodiment was continued for 20 minutes, the H2S conversion rate was measured to be 78.1%; and no abnormality was found after continuous discharge for 100 hours, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this embodiment was 15.3eV / H2S molecule.

[0153] Example 4

[0154] This embodiment uses a plasma reaction device similar to that of Embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, except that in this embodiment:

[0155] The ratio of L2 to the thickness D1 of the blocking medium is 35:1.

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

[0157] Results: After the hydrogen sulfide decomposition reaction of this embodiment was continued for 20 minutes, the H2S conversion rate was measured to be 72.3%; and no abnormality was found after continuous discharge for 100 hours, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this embodiment was 18.8eV / H2S molecule.

[0158] Example 5

[0159] This embodiment uses a plasma reaction device similar to that of Embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, except that in this embodiment:

[0160] H1:L3=1:1500.

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

[0162] Results: After the hydrogen sulfide decomposition reaction of this embodiment was continued for 20 minutes, the H2S conversion rate was measured to be 75.7%; and no abnormality was found after continuous discharge for 100 hours, and the discharge state and H2S conversion rate remained stable. The decomposition energy consumption of this embodiment was 17.7eV / H2S molecule.

[0163] It can be seen from the above results that the low-temperature plasma reaction equipment provided by the present invention can significantly improve the conversion rate of hydrogen sulfide when decomposing hydrogen sulfide compared with the prior art, and the reaction equipment provided by the present invention can maintain a high hydrogen sulfide conversion rate for a long period of time at low decomposition energy consumption.

[0164] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for decomposing hydrogen sulfide, the method being implemented in a plasma device, the device comprising: A first cavity (1), wherein the first cavity (1) is respectively provided with a first inlet (11) and a first outlet; A second cavity (2), the second cavity (2) being nested inside the first cavity (1), and the second cavity (2) being respectively provided with a second inlet (21) and a second outlet (22); an inner electrode (3), at least a portion of the inner electrode (3) extending into the first cavity (1); an external electrode (4), forming at least part of a side wall of the first cavity (1) or being arranged around an outer side wall of the first cavity (1); as well as a blocking medium (6), forming at least part of the side wall of the first cavity (1) or being arranged around the inner wall of the first cavity (1), and the blocking medium (6) is arranged between the inner electrode (3) and the outer electrode (4), so that the discharge area between the inner electrode (3) and the outer electrode (4) is separated by the blocking medium (6); The inner electrode (3) and the outer electrode (4) are both solid electrodes, and their shapes match each other to form an equal-diameter structure; The distance between the outer wall of the inner electrode (3) and the inner wall of the outer electrode (4) is L1, the thickness of the blocking medium (6) is D1, L2=L1-D1, and the ratio between L2 and D1 is (0.2-15):1; The first inlet (11) is arranged at the upper part of the first cavity (1), the first 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 first cavity (1), and the liquid product outlet (13) is arranged at the bottom of the first cavity (1); The gas product outlet (12) is arranged below the discharge area, and the ratio between the height H1 of the arrangement position of the gas product outlet (12) relative to the bottom of the first cavity (1) and the length L3 of the discharge area is: H1:L3=1:(0.5-1000); The method comprises: connecting one of an outer electrode (4) and an inner electrode (3) of the plasma device to a high voltage power source and grounding the other to perform dielectric barrier discharge, introducing a raw material gas containing hydrogen sulfide into the first cavity (1) from a first inlet (11) of the first cavity (1) of the plasma device to perform a decomposition reaction of the hydrogen sulfide, and leading the stream obtained after the decomposition out from a first outlet, and continuously introducing a heat-conducting medium into the second cavity (2) of the plasma device from a second inlet (21) and leading the heat-conducting medium out from a second outlet (22) to control the temperature of the first cavity (1) of the plasma device; The conditions of the dielectric barrier discharge include: a discharge voltage of 5 kV to 15 kV; a discharge frequency of 500 to 13000 Hz; The conditions of the decomposition reaction include: a reaction temperature of 119-444.6°C and a reaction pressure of 0-0.6MPa; The residence time of the raw gas containing hydrogen sulfide in the discharge region of the plasma device is 2×10 -5 ~60s.

2. The method according to claim 1, wherein: The conditions of the decomposition reaction include: the reaction pressure is 0-0.3 MPa.

3. The method according to claim 1 or 2, wherein: The decomposition reaction of hydrogen sulfide is carried out in the presence of a carrier gas, and the carrier gas is selected from at least one of nitrogen, hydrogen, helium, argon, water vapor, carbon monoxide, carbon dioxide, methane, ethane and propane.

4. The method according to claim 3, wherein: The decomposition reaction of hydrogen sulfide is carried out in the presence of a carrier gas, and the carrier gas is selected from at least one of hydrogen, argon, helium and nitrogen.

5. The method according to claim 1, wherein: The inner electrode (3) forms at least part of the side wall of the second cavity (2).

6. The method according to claim 1, wherein: The inner electrode (3) is arranged around the outer wall of the second cavity (2).

7. The method according to claim 1, wherein: The inner electrode (3) is arranged around the inner wall of the second cavity (2).

8. The method according to claim 7, wherein: The device contains a double barrier medium, and the other barrier medium forms at least part of the side wall of the second cavity (2), and the D1 is the sum of the thicknesses of the barrier medium (6) and the other barrier medium.

9. The method according to claim 1, wherein: The outer electrode (4) is arranged around the outer side wall of the first cavity (1), and the first cavity (1) is formed by a blocking medium (6).

10. The method according to claim 1, wherein: The outer electrode (4) is arranged around the outer side wall of the first cavity (1), and the blocking medium forms at least a part of the side wall of the first cavity (1).

11. The method according to claim 1, wherein: The number of the first cavity (1) is one.

12. The method according to claim 1, wherein: The number of the first cavities (1) is more than 2, and each of the first cavities (1) is respectively provided with the inner electrode (3), the outer electrode (4) and the blocking medium (6).

13. The method according to claim 12, wherein: The internal electrodes (3) are connected in parallel to each other.

14. The method according to claim 12, wherein: The external electrodes (4) are connected in parallel with each other.

15. The method according to claim 1, wherein: The material of the blocking medium is an electrical insulating material.

16. The method according to claim 1, wherein: The material of the blocking medium is selected from at least one of glass, quartz, ceramic, enamel, polytetrafluoroethylene and mica.

17. The method according to claim 1, wherein: The outer electrode (4) and the inner electrode (3) are each independently selected from conductive materials.

18. The method according to claim 1, wherein: The outer electrode (4) and the inner electrode (3) are each independently selected from at least one of a graphite tube, graphite powder, a metal rod, a metal foil, a metal mesh, a metal tube, a metal powder and a graphite rod.

19. The method according to claim 1, wherein: The device also includes a grounding wire (5), one end of which is electrically connected to a grounding electrode, the grounding electrode being one of the outer electrode (4) and the inner electrode (3), and the other of the outer electrode (4) and the inner electrode (3) being a high voltage electrode.

20. The method according to claim 1, wherein: The second inlet (21) and the second outlet (22) are respectively arranged at the lower part and the upper part of the second cavity (2).

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