CN111377409A - Plasma apparatus and method for decomposing hydrogen sulfide - Google Patents

Abstract

The 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), and an outer electrode (4). ), and a blocking medium (6), the inner electrode (3) and the outer electrode (4) are both solid electrodes, and their shapes cooperate with each other to form an equal diameter structure. The low-temperature plasma reactor provided by the invention can realize the continuous and stable progress of the hydrogen sulfide decomposition process under a significantly higher hydrogen sulfide conversion rate, and the device can realize long-term operation.

Description

Plasma equipment and method for decomposing hydrogen sulfide

technical field

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

Background technique

Hydrogen sulfide (H ₂ S) is a highly toxic and foul-smelling acid gas, which not only causes corrosion of metals and other materials, but also harms human health and pollutes the environment. At present, China's large and medium-sized oil refineries all use the traditional Claus method to treat the tail gas containing H ₂ S and recover the sulfur. The method recovers only the sulfur in the hydrogen sulfide, but converts the precious hydrogen into water. From the perspective of comprehensive utilization of resources, in the traditional hydrogen sulfide recovery process, hydrogen resources have not been effectively utilized.

Therefore, the decomposition of hydrogen sulfide into sulfur and hydrogen has gradually become a technical field that domestic and foreign researchers focus on.

At present, hydrogen sulfide decomposition methods mainly include: high temperature decomposition method, electrochemical method, photocatalytic method and low temperature plasma method. Among the aforementioned methods, the high-temperature thermal decomposition method is relatively mature in industrial technology, but the thermal decomposition of hydrogen sulfide strongly depends 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 also only 20%. In addition, high temperature conditions have higher requirements on the material of the reactor, which will also increase the operating cost. In addition, due to the low thermal decomposition conversion rate of hydrogen sulfide, a large amount of hydrogen sulfide gas needs to be separated from the tail gas and circulated in the system, thus reducing the efficiency of the device and increasing the energy consumption, all of which bring difficulties to its large-scale industrial application . Although the use of membrane technology can effectively separate the products to break the equilibrium limit and improve the conversion rate of hydrogen sulfide, the thermal decomposition temperature often exceeds the limit heat resistance temperature of the membrane, which destroys the structure of the membrane material. The electrochemical method has disadvantages such as many operation steps, serious equipment corrosion, poor reaction stability and low efficiency. Photocatalytic decomposition of hydrogen sulfide mainly draws on the research of photocatalytic water splitting, and the research focuses on the development of high-efficiency semiconductor photocatalysts. Using solar energy to decompose hydrogen sulfide has the advantages of low energy consumption, mild reaction conditions and simple operation, and is a relatively economical method. However, this method has problems such as small throughput, low catalytic efficiency and easy deactivation of the catalyst.

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

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

CN102408095A uses dielectric barrier discharge and photocatalyst to synergistically decompose hydrogen sulfide, and the method is to fill the solid catalyst with photocatalytic activity in the plasma area. However, this method suffers from the disadvantage that the sulfur produced by the decomposition of hydrogen sulfide can be deposited under the catalyst bed.

CN103204466A discloses a temperature-controlled hydrogen sulfide decomposition device and method. The device is characterized in that the central electrode is metal, and the ground electrode is a temperature-controlled circulating liquid. The temperature of the liquid ground electrode is controlled, so that the hydrogen sulfide decomposition process can be continuous. Stable progress. In addition, CN103204467A discloses a device and method for continuously and stably decomposing hydrogen sulfide to produce hydrogen. The prior art is characterized in that the center electrode is a metal, the ground electrode is a temperature-controllable circulating liquid, and the temperature is controlled by the liquid ground electrode. , the inlet direction of the raw material is circumferential inlet, and it passes through the discharge area in the reverse direction along the axial direction in a spiral pattern, so that the produced sulfur is centrifuged out in time. However, in the methods disclosed in CN103204466A and CN103204467A, in order to ensure that hydrogen sulfide is decomposed as fully as possible, it is necessary to control the flow rate of hydrogen sulfide to make its residence time in the inner barrel of the reactor longer and to control the size of the inner barrel so that the unit volume in the inner barrel is The gas can obtain more electrical energy, and since the current prior art cannot provide a power source with higher power, the methods disclosed in CN103204466A and CN103204467A are used to control the residence time of hydrogen sulfide and control the size of the inner cylinder to make the inner The electric energy obtained per unit volume of gas in the cylinder can only make the maximum conversion rate of hydrogen sulfide reach about 20%, and when the maximum conversion rate of hydrogen sulfide reaches about 20%, the energy consumption of hydrogen sulfide decomposition reaction is quite high, Not suitable for large industrial applications. Further, the methods disclosed in CN103204466A and CN103204467A also have the defect that there are very few types of liquid ground electrodes available, and the salt solutions disclosed by them can generally only maintain the temperature of the reactor below 100 °C, and below 100 °C, the elemental Sulfur is generally solid, which can easily cause clogging of the reactor.

SUMMARY OF THE INVENTION

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 it is used for the decomposition of hydrogen sulfide, and to provide a new method that can improve the hydrogen sulfide conversion rate. And a low-temperature plasma reaction device for reducing decomposition energy consumption and a method for decomposing hydrogen sulfide using the reaction device.

The difference between "side wall" and "outer side wall" and "inner side wall" in the present invention is: "outer side wall" and "inner side wall" respectively represent the outer surface and inner surface of "side wall", if it is "side wall" It means "outer side wall" and/or "inner side wall".

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

a first cavity, the first cavity is respectively provided with a first inlet and a first outlet;

a second cavity, the second cavity is nested inside the first cavity, and the second cavity is respectively provided with a second inlet and a second outlet;

an inner electrode, at least part of the inner electrode protrudes into the first cavity;

an external electrode that forms at least part of the sidewall of the first cavity or is disposed around the outer sidewall of the first cavity; and

A blocking medium, which forms at least part of the sidewall of the first cavity or is arranged around the inner sidewall of the first cavity, and the blocking medium is arranged between the inner electrode and the outer electrode, so that a discharge region between the inner electrode and the outer electrode is separated by the barrier medium;

The inner electrode and the outer electrode are both solid electrodes, and their shapes cooperate with each other to form an equal diameter structure;

The distance between the outer sidewall of the inner electrode and the inner sidewall of the outer electrode is L ₁ , the thickness of the blocking medium is D ₁ , L ₂ =L ₁ -D ₁ , and between L ₂ and D ₁ The proportional relationship is (0.1～100):1.

"Equal diameter structure" means: the minimum distance between any point of the outer side wall of the inner electrode and the inner side wall of the outer electrode and the distance between other points of the outer side wall of the inner electrode and the inner side wall of the outer electrode structures with the same minimum distance between them.

Preferably, the ratio between L ₂ and D ₁ is (0.1-30):1; more preferably (0.2-15):1.

According to a preferred embodiment, the inner electrode forms at least part of the side wall of the second cavity.

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

According to a further preferred embodiment, the inner electrode is arranged around the inner side wall of the second cavity. In this preferred embodiment, it is preferred that the device contains a dual barrier medium, and the other barrier medium forms at least part of the sidewall of the second cavity, and the D ₁ is the barrier medium and the other barrier medium. a sum of the thicknesses of the blocking medium.

In order to distinguish the description, the present invention refers to the blocking medium forming at least part of the sidewall of the first cavity or surrounding the inner sidewall of the first cavity as a "blocking medium"; The blocking medium of at least part of the sidewall of the cavity is referred to as "another blocking medium". The materials of the blocking medium of the present invention and another blocking medium may be the same or different.

In the present invention, the shape of the first cavity and the second cavity may be, for example, a cylinder shape, a serpentine shape, a fin shape, an S shape, or a wave shape.

According to a preferred embodiment, the outer electrode is disposed around the outer sidewall of the first cavity, and the first cavity is formed by a blocking medium.

According to another preferred embodiment, the outer electrode is disposed around the outer sidewall of the first cavity, and the blocking medium forms at least part of the sidewall of the first cavity.

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

The aforementioned low-temperature plasma reaction equipment provided by the present invention is preferably a jacket-type dielectric barrier discharge reaction equipment with a coaxial structure, the basic structure of which mainly includes an inner electrode, an outer electrode, a barrier medium, etc. Cyclic heating or cooling of the discharge reaction equipment enables flexible temperature control of the discharge area. In particular, the present invention can significantly improve the conversion rate of hydrogen sulfide compared with the prior art by controlling the proportional relationship between L ₂ and the thickness D ₁ of the blocking medium within a specific range, and when applying a solid inner electrode and a solid outer electrode. Reduce decomposition energy consumption.

The jacket structure design of the present invention can make the heat conduction medium circulate in the shell layer, and the entire reaction equipment can be maintained within a certain temperature range while ensuring the discharge intensity, so that the generated sulfur flows out of the reaction equipment in liquid form, which can effectively avoid The solidification of the sulfur generated by the decomposition of hydrogen sulfide can achieve a high conversion rate and at the same time make the decomposition process continue and stably achieve long-term operation.

Preferably, the number of the first cavity is one.

According to a preferred embodiment, the number of the first cavities is two or more, and each of the first cavities is provided with the inner electrode, the outer electrode and the blocking medium, respectively. In this preferred embodiment, preferably, each of the inner electrodes is connected in parallel with each other. In this preferred embodiment, preferably, each of the external electrodes is connected in parallel with each other.

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

Preferably, the outer electrode and the inner electrode are conductive materials. Preferably, the outer electrode and the inner electrode may each be independently selected from at least one of graphite tubes, graphite powders, metal rods, metal foils, metal meshes, metal tubes, metal powders and graphite rods.

The metal rods and metal pipes may include elemental metal rods, alloyed metal rods, elemental metal pipes, and alloyed metal pipes. The metal powder may comprise elemental metal powder, alloyed metal powder, or a mechanical mixture of elemental metal powder and/or alloyed metal powder. The material for forming the electrode (including the inner electrode and the outer electrode) of the present invention can also be other rod-shaped and tubular materials with electrical conductivity.

In the present invention, it is preferable that 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.

Preferably, the reaction device of the present invention further comprises a ground wire, and one end of the ground wire is electrically connected to the outer electrode or the inner electrode.

Preferably, the first inlet is arranged at the upper part of the first cavity, and the first outlet is arranged at the lower part and/or the bottom of the first cavity.

Preferably, the first outlet includes a gas product outlet and a liquid product outlet, and the gas product outlet is arranged at a lower portion of the first cavity, and the liquid product outlet is arranged at a lower portion of the first cavity bottom.

Preferably, the gas product outlet is arranged below the discharge region, and the position of the gas product outlet is between the height H1 of the bottom of the _first cavity and the length L3 _of the discharge region The proportional relationship is: H ₁ : L ₃ =1:(0.05～25000); preferably H ₁ :L ₃ =1:(0.1～10000); more preferably H ₁ :L ₃ =1:(0.5～1000 ).

In the present invention, the "discharge region" refers to a region where the inner electrode, the outer electrode and the blocking medium completely overlap.

In the present invention, the ratio of the inner diameter of the first cavity to the diameter of the first outlet may be (0.1˜100):1.

The ratio of the aperture of the first inlet to the aperture of the first outlet of the present invention may be (0.1˜120):1.

The ratio between the length of the first cavity and the inner diameter of the first cavity in the present invention may be (0.5˜500):1. The inner diameter of the first cavity represents the distance from the axis of the first cavity to the outer sidewall of the first cavity.

Preferably, the second inlet and the second outlet are provided at the lower and upper portions of the second cavity, respectively.

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

In the present invention, the temperature of the reaction equipment with the jacket structure can be maintained, for example, between 119 and 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.

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

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

In a second aspect, the present invention provides a method for decomposing hydrogen sulfide. The method is implemented in the low-temperature plasma reaction device described in the first aspect of the present invention, and the method includes: connecting an outer electrode of the low-temperature plasma reaction device with One of the inner electrodes is connected to the high-voltage power supply, and the other is grounded to perform dielectric barrier discharge, and the raw material gas containing hydrogen sulfide is introduced from the first inlet of the first cavity of the low-temperature plasma reaction equipment to the first cavity. The decomposition reaction of hydrogen sulfide is carried out in the cavity, and the stream obtained after the decomposition is led out from the first outlet, and the heat transfer medium is continuously introduced into the second cavity of the low-temperature plasma reaction device from the second inlet and led out from the second outlet. The heat transfer medium is used to control the temperature of the first cavity of the low temperature plasma reaction device.

Preferably, the dielectric barrier discharge conditions include: the discharge voltage is 2kV-80kV, preferably 5kV-30kV, more preferably 5kV-20kV, still more preferably 5kV-15kV; the discharge frequency is 200-30000Hz, preferably 500 to 15000 Hz, more preferably 500 to 13000 Hz.

Preferably, the conditions of the decomposition reaction include: the reaction temperature is 0-800°C, preferably 40-500°C, more preferably 119-444.6°C; the reaction pressure is 0-0.6Mpa, preferably 0-0.3MPa.

Preferably, the residence time of the raw material gas containing hydrogen sulfide in the discharge region of the low temperature plasma reaction equipment is 1×10 ^-5 to 120s, preferably 2×10 ^-5 to 60s.

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

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

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

In the present invention, the raw material gas does not include the aforementioned carrier gas of the present invention, and the raw material gas is pure hydrogen sulfide gas or industrial waste gas containing hydrogen sulfide and other gases obtained in industrial production. The raw material gas may contain the same kind of gas as the carrier gas defined in the present invention, but the carrier gas defined in the present invention is a gas that is actively added to be mixed with the raw material gas, and the method of the present invention can adjust the added carrier gas. Air volume is controlled as needed.

The following provides a preferred embodiment of applying the aforementioned low-temperature plasma reaction equipment of the present invention to decompose hydrogen sulfide:

A shielding gas such as nitrogen gas is introduced into the first cavity of the low temperature plasma reaction apparatus from the first inlet to remove air in the discharge area, and the gas is led out from the first outlet. At the same time, the heat conducting medium is introduced into the second cavity from the second inlet, and the introduced heat conducting medium is led out from the second outlet. The temperature of the heat transfer medium is maintained at the temperature required for the system reaction. Then, feed the raw material gas containing hydrogen sulfide into the first cavity of the low-temperature plasma reaction equipment from the first inlet. After the gas flow of the raw material is stable, turn on the high-voltage power supply. Plasma discharge field. The hydrogen sulfide gas is ionized in the discharge area and decomposed into hydrogen and elemental sulfur, and the elemental sulfur produced by the discharge flows down slowly along the first cavity wall and flows out from the first outlet.

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

In addition, the low-temperature plasma reaction equipment provided by the present invention can also be used in a large-flow, high-concentration hydrogen sulfide treatment process.

Description of drawings

FIG. 1 is a schematic structural diagram of a preferred specific embodiment of the low-temperature plasma reaction equipment provided by the present invention.

Description of reference numerals

1. The first cavity 2. The second cavity

11. The first entrance 21. The second entrance

12. Gas product outlet 22. Second outlet

13. Liquid product export

3. Inner electrode

4. External electrode

5. Ground wire

6, blocking medium

Detailed ways

The endpoints of ranges and any values disclosed herein are not limited to the precise ranges or values, which are to be understood to encompass values proximate to those ranges or values. For ranges of values, the endpoints of each range, the endpoints of each range and the individual point values, and the individual point values can be combined with each other to yield one or more new ranges of values that Ranges should be considered as specifically disclosed herein.

The structure of a preferred specific embodiment of the low-temperature plasma reaction apparatus of the present invention is provided below in conjunction with FIG. 1, specifically:

The reaction equipment has a coaxial jacket structure, and the reaction equipment includes:

The first cavity 1, the first cavity 1 is respectively provided with a first inlet 11 and a first outlet;

The second cavity 2, the second cavity 2 is nested inside the first cavity 1, and the second cavity 2 is provided with a second inlet 21 and a second outlet 22 respectively;

an inner electrode 3, the inner electrode 3 is arranged in the first cavity 1;

an outer electrode 4, which forms at least part of the sidewall of the first cavity 1 or is arranged around the outer sidewall of the first cavity 1; and

A blocking medium, which forms at least part of the sidewall of the first cavity 1 or is arranged around the inner sidewall of the first cavity 1 , and is provided on the inner electrode 3 and the outer between the electrodes 4, so that the discharge area between the inner electrode and the outer electrode is separated by the blocking medium;

The inner electrode 3 and the outer electrode 4 are both solid electrodes, and the shapes of the two cooperate with each other to form an equal diameter structure;

The distance between the outer sidewall of the inner electrode 3 and the inner sidewall of the outer electrode 4 is L ₁ , the thickness of the blocking medium 6 is D ₁ , L ₂ =L ₁ -D ₁ , and L ₂ and D The ratio between ₁ is (0.1-100):1, preferably the ratio between L ₂ and D ₁ is (0.1-30):1; more preferably (0.2-15):1.

Preferably, the inner electrode 3 forms at least part of the side wall of the second cavity 2 .

According to a preferred embodiment, the inner electrode 3 is arranged around the outer side wall of the second cavity 2 .

According to a preferred specific embodiment, the inner electrode 3 is arranged around the inner side wall of the second cavity 2 . In this preferred embodiment, it is preferred that the device contains double blocking mediums, and another blocking medium (not marked in the figure) forms at least part of the sidewall of the second cavity 2, and the D ₁ is all The sum of the thicknesses of the blocking medium 6 and the other blocking medium.

Preferably, the outer electrode 4 is disposed around the outer sidewall of the first cavity 1 , and the first cavity 1 is formed by a blocking medium 6 .

Preferably, the outer electrode 4 is disposed around the outer sidewall of the first cavity 1 , and the blocking medium forms at least part of the sidewall of the first cavity 1 .

Preferably, the number of the first cavity 1 is one.

According to another preferred embodiment, the number of the first cavities 1 is two or more, and each of the first cavities 1 is provided with the inner electrode 3 , the outer electrode 4 and the the blocking medium 6 . In this preferred embodiment, preferably each of the inner electrodes 3 is connected in parallel with each other; preferably each of the outer electrodes 4 is connected in parallel with each other.

Preferably, the reaction device further includes a ground wire 5 , and one end of the ground wire 5 is electrically connected to the inner electrode 3 or the outer electrode 4 .

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.

Preferably, the first inlet 11 is arranged at the upper part of the first cavity 1 , and the first outlet is arranged at the lower part and/or the bottom of the first cavity 1 .

Preferably, the second inlet 21 and the second outlet 22 are provided at the lower and upper portions of the second cavity 2, respectively.

Preferably, the first outlet includes 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 lower part of the first cavity 1. The bottom of the first cavity 1 .

Preferably, the gas product outlet 12 is arranged below the discharge area, and the location of the gas product outlet 12 is relative to the height H ₁ of the bottom of the first cavity 1 and the length L of the discharge area The proportional relationship between ₃ is: H ₁ : L ₃ =1:(0.05～25000); preferably H ₁ :L ₃ =1:(0.1～10000); more preferably H ₁ :L ₃ =1:( 0.5～1000).

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

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

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

(2) The reaction equipment is equipped 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 generated by the discharge decomposition of hydrogen sulfide can flow out of the discharge area smoothly, so as to avoid the solidification of sulfur and block the reaction equipment, so that the The discharge continues stably.

(3) The proportional relationship between L ₂ and the thickness D ₁ of the blocking medium in the reaction equipment is: (0.1-100): 1, preferably (0.1-30): 1, more preferably (0.2-15) : 1, in coordination with the remaining structures of the reaction equipment of the present invention, the conversion rate of hydrogen sulfide can be significantly improved and the decomposition energy consumption can be reduced.

The present invention will be described in detail below by means of examples. In the following examples, unless otherwise specified, various raw materials used are from commercial sources.

The thicknesses of the blocking media in the following examples and comparative examples are all the same.

The conversion of hydrogen sulfide in the following examples was calculated according to the following formula:

Decomposition rate of hydrogen sulfide % = moles of converted hydrogen sulfide / moles of initial hydrogen sulfide × 100%

The energy consumption for decomposing hydrogen sulfide in the following example is obtained by oscilloscope detection and calculation using Lissajous figures.

Unless otherwise specified, the following inner electrodes are all high-voltage electrodes, and the outer electrodes are all solid ground electrodes.

Example 1

The low-temperature plasma reaction equipment shown in FIG. 1 is used to carry out the hydrogen sulfide decomposition reaction. The specific structure and structural parameters of the low-temperature plasma reaction equipment are as follows, and the inner electrode of this embodiment is a high-voltage electrode:

The reaction equipment includes:

a first cavity, the first cavity is provided with a first inlet, a gas product outlet and a liquid product outlet respectively, wherein all the side walls of the first cavity are formed by a blocking medium, forming the blocking medium The material is hard glass;

a second cavity, the second cavity is nested inside the first cavity, and the second cavity is respectively provided with a second inlet and a second outlet;

an inner electrode, the inner electrode forms the side wall of the second cavity, the material for forming the inner electrode is stainless steel, and the inner electrode is connected to a high-voltage power supply;

an outer electrode, the outer electrode is wrapped on the outer side wall of the first cavity, the material for forming the outer electrode is 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 ground electrode;

The ratio of L ₂ to the thickness D ₁ of the blocking medium is 4:1; and H ₁ : L ₃ =1:100;

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

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

The operating steps of the low temperature plasma reaction equipment:

Nitrogen gas is introduced into the first cavity of the low temperature plasma reaction apparatus from the first inlet to clear 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) was introduced into the second cavity from the second inlet, and the introduced heat-conducting medium was drawn out from the second outlet, and the temperature of the heat-conducting medium was maintained at 145°C.

Then, the H ₂ S/Ar mixed gas was introduced into the first cavity of the low temperature plasma reaction equipment from the first inlet, wherein the volume fraction of H ₂ S was 30%, and the flow rate of the mixed gas was controlled to make the average residence time of the gas in the discharge area. For 16.7s, the reaction pressure in the first cavity of the reactor was maintained at 0.12MPa in this example. After the H ₂ S/Ar mixed gas was passed into the reaction equipment for 30 minutes, the AC high-voltage power supply was turned on, and a plasma discharge field was 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 flows down slowly along the first cavity wall, and the liquid product is intermittently released. The reacted gas flows out from the gas product outlet.

Results: The H ₂ S conversion rate was 78.7% after the hydrogen sulfide decomposition reaction in this example continued for 20 minutes; and the discharge state and H ₂ S conversion rate remained stable after 100 hours of continuous discharge. And the energy consumption of decomposition in this embodiment is 12.8 eV/H ₂ S molecule (the energy consumed per decomposing 1 molecule of H ₂ S is 12.8 eV).

Comparative Example 1

This comparative example adopts the low temperature plasma reaction equipment similar to Example 1 to carry out the hydrogen sulfide decomposition reaction, the difference is:

The ground electrode in this comparative example is a liquid ground electrode, and is LiCl and AlCl ₃ in a molten state 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 is placed on the first part of the reaction equipment. in the second cavity. In this comparative example, the external electrode is arranged around the outer side wall of the first cavity, and the external electrode is connected to a high-voltage power supply.

The flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge area was 23.7s.

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

The rest are the same as in Example 1.

And this comparative example adopts the same operation method as Example 1 to carry out the hydrogen sulfide decomposition reaction.

Results: The H ₂ S conversion rate of the comparative example was 17.9% after the hydrogen sulfide decomposition reaction continued for 20 min, and the H ₂ S conversion rate decreased to 6.6% after the continuous discharge for 1.5 h.

The decomposition energy consumption of this comparative example is 124 eV/H ₂ S molecule.

Comparative Example 2

This comparative example was carried out using a low temperature plasma reaction equipment similar to that of Comparative Example 1, with the following differences:

The ratio of L ₂ to the thickness D ₁ of the blocking medium in this comparative example is 0.08:1.

The flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge area was 21.4s.

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

The rest are the same as in Comparative Example 1.

Results: The H ₂ S conversion rate was 25.4% after the hydrogen sulfide decomposition reaction of this comparative example continued for 20 min, and the H ₂ S conversion rate decreased to 6.9% after the continuous discharge for 1.5 h.

The decomposition energy consumption of this comparative example is 132 eV/H ₂ S molecule.

Example 2

This embodiment adopts the plasma reaction equipment similar to that of embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, the difference is that in this embodiment:

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 is used as a high-voltage electrode, and the material for forming the external electrode is stainless steel metal foil; The side walls of the two cavities are grounded as inner electrodes, so that the side walls of the second cavity serve as ground electrodes.

The blocking medium is arranged around the inner sidewall of the first cavity;

The ratio of L ₂ to the thickness D ₁ of the blocking medium is 6:1; and H ₁ :L ₃ =1:46.

In this embodiment, a mixed gas of H ₂ S/Ar is passed from the first inlet to the first cavity of the low temperature plasma reaction device, wherein the volume fraction of H ₂ S is 30%. The average residence time was 6.4s, and the reaction pressure in the first cavity of the reactor was maintained at 0.05MPa in this example. After the H ₂ S/Ar mixed gas was passed into the reaction equipment for 30 minutes, the AC high-voltage power supply was turned on, and a plasma discharge field was 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 17.5kV, the frequency is 7.8kHz, and the current is 1.14A.

The rest are the same as in Example 1.

Results: After the hydrogen sulfide decomposition reaction in this example continued for 20 min, the H ₂ S conversion rate was 78.5%; and there was no abnormality in the continuous discharge for 100 h, and the discharge state and the H ₂ S conversion rate remained stable. And the decomposition energy consumption of this embodiment is 13.1 eV/H ₂ S molecule.

Example 3

This embodiment adopts the plasma reaction equipment similar to that of embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, the difference is that in this embodiment:

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

The blocking medium is arranged around the inner sidewall of the first cavity;

The ratio of L ₂ to the thickness D ₁ of the blocking medium is 0.5:1; and H ₁ : L ₃ =1:200.

In this embodiment, the H ₂ S/Ar mixed gas is passed from the first inlet to the first cavity of the low-temperature plasma reaction device, wherein the volume fraction of H ₂ S is 25%, and the flow rate of the mixed gas is controlled so that the gas flows in the discharge area. The average residence time was 3.4s, and the reaction pressure in the first cavity of the reactor was maintained at 0.27MPa in this example. After the H ₂ S/Ar mixed gas was passed into the reaction equipment for 30 minutes, the AC high-voltage power supply was turned on, and a plasma discharge field was 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 19.7kV, the frequency is 12.7kHz, and the current is 0.97A.

The rest are the same as in Example 1.

Results: After the hydrogen sulfide decomposition reaction in this example continued for 20 min, the H ₂ S conversion rate was 78.1%; and there was no abnormality in the continuous discharge for 100 h, and the discharge state and the H ₂ S conversion rate remained stable. And the decomposition energy consumption of this embodiment is 15.3 eV/H ₂ S molecule.

Example 4

This embodiment adopts the plasma reaction equipment similar to that of embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, the difference is that in this embodiment:

The ratio of L2 to the thickness D1 _of the blocking medium is 35: ₁ .

The rest are the same as in Example 1.

Results: After the hydrogen sulfide decomposition reaction in this example continued for 20 min, the H ₂ S conversion rate was 72.3%; and there was no abnormality in the continuous discharge for 100 h, and the discharge state and the H ₂ S conversion rate remained stable. And the energy consumption of decomposition in this embodiment is 18.8 eV/H ₂ S molecule.

Example 5

This embodiment adopts the plasma reaction equipment similar to that of embodiment 1 to carry out the decomposition reaction of hydrogen sulfide, the difference is that in this embodiment:

H ₁ : L ₃ =1:1500.

The rest are the same as in Example 1.

Results: The H ₂ S conversion rate was 75.7% after the hydrogen sulfide decomposition reaction in this example continued for 20 min; and the discharge state and H ₂ S conversion rate remained stable after 100 hours of continuous discharge. And the decomposition energy consumption of this embodiment is 17.7 eV/H ₂ S molecule.

It can be seen from the above results that the conversion rate of hydrogen sulfide can be significantly improved compared to the prior art when the low-temperature plasma reaction equipment provided by the present invention is used for the decomposition of hydrogen sulfide, and the reaction equipment provided by the present invention can be used at a low decomposition energy. High hydrogen sulfide conversion is maintained over a long period of time.

The preferred embodiments of the present invention have been described above in detail, however, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, a variety of simple modifications can be made to the technical solutions of the present invention, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the content disclosed in the present invention. All belong to the protection scope of the present invention.

Claims (19)

1. A plasma device comprising: a first cavity (1), wherein a first inlet (11) and a first outlet are respectively provided on the first cavity (1); A second cavity (2), the second cavity (2) is nested inside the first cavity (1), and the second cavity (2) is respectively provided with a second inlet ( 21) and the second exit (22); an inner electrode (3), at least part of the inner electrode (3) protruding into the first cavity (1); an outer electrode (4), forming at least part of the sidewall of the first cavity (1) or arranged around the outer sidewall of the first cavity (1); and A blocking medium (6), which forms at least part of the sidewall of the first cavity (1) or is arranged around the inner sidewall of the first cavity (1), and the blocking medium (6) is provided on the 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 barrier medium (6); The inner electrode (3) and the outer electrode (4) are both solid electrodes, and their shapes cooperate with each other to form an equal diameter structure; The distance between the outer sidewall of the inner electrode (3) and the inner sidewall of the outer electrode (4) is L ₁ , the thickness of the blocking medium (6) is D ₁ , and L ₂ =L ₁ -D ₁ , and the proportional relationship between L ₂ and D ₁ is (0.1-100): 1, preferably the proportional relationship between L ₂ and D ₁ is (0.1-30): 1; more preferably (0.2-15): 1. 2. The plasma apparatus according to claim 1, wherein the inner electrode (3) forms at least part of the sidewall of the second cavity (2). 3. The plasma apparatus according to claim 1, wherein the inner electrode (3) is arranged around the outer sidewall of the second cavity (2). 4. The plasma apparatus according to claim 1, wherein the inner electrode (3) is arranged around the inner sidewall of the second cavity (2). 5. The plasma apparatus according to claim 4, wherein a double barrier medium is contained in the apparatus, and the other barrier medium forms at least part of the sidewall of the second cavity ( ₂ ), and the D1 is The sum of the thicknesses of the blocking medium (6) and the other blocking medium. 6. The plasma apparatus according to any one of claims 1-5, wherein the outer electrode (4) is arranged around the outer sidewall of the first cavity (1), and the first The cavity (1) is formed by the barrier medium (6). 7. The plasma apparatus according to any one of claims 1-5, wherein the outer electrode (4) is arranged around the outer sidewall of the first cavity (1), and the blocking medium At least part of the side walls of the first cavity (1) are formed. 8. The plasma apparatus according to any one of claims 1-7, wherein the number of the first cavity (1) is one. 9. The plasma apparatus according to any one of claims 1-8, wherein the number of the first cavities (1) is two or more, and each of the first cavities (1) has The inner electrode (3), the outer electrode (4) and the blocking medium (6) are respectively provided. 10. The plasma apparatus according to claim 9, wherein the respective inner electrodes (3) are connected in parallel with each other; Preferably, the respective external electrodes (4) are connected in parallel with each other. 11. The plasma device according to any one of claims 1-10, wherein the material of the blocking medium is an electrical insulating material; preferably selected from glass, quartz, ceramics, enamel, polytetrafluoroethylene and mica at least one of; The outer electrode (4) and the inner electrode (3) are each independently selected from conductive materials; preferably each independently selected from graphite tubes, graphite powders, metal rods, metal foils, metal meshes, metal tubes, metal powders and At least one of graphite rods. 12. The plasma device according to any one of claims 1-11, wherein the device further comprises a ground wire (5), one end of the ground wire is electrically connected to a ground electrode, and the ground electrode is the One of the outer electrode (4) and the inner electrode (3), and the other of the outer electrode (4) and the inner electrode (3) is a high voltage electrode. 13. The plasma apparatus according to any one of claims 1-12, wherein the first inlet (11) is arranged in the upper part of the first cavity (1), and the first outlet is arranged at the lower and/or bottom of the first cavity (1). 14. The plasma apparatus according to claim 13, wherein the first outlet comprises a gaseous product outlet (12) and a liquid product outlet (13), and the gaseous product outlet (12) is provided at the first The lower part of the cavity (1), and the liquid product outlet (13) are arranged at the bottom of the first cavity (1). 15. The plasma apparatus according to claim 14, wherein the gas product outlet (12) is arranged below the discharge region, and the gas product outlet (12) is arranged in a position relative to the first The proportional relationship between the height H ₁ of the bottom of the cavity (1) and the length L ₃ of the discharge region is: H ₁ : L ₃ =1: (0.05-25000); preferably H ₁ : L ₃ =1: (0.1 to 10000); more preferably H ₁ : L ₃ =1: (0.5 to 1000). 16. The plasma apparatus according to any one of claims 1-15, wherein the second inlet (21) and the second outlet (22) are respectively provided in the second cavity (2) the lower and upper parts. 17. A method for decomposing hydrogen sulfide, the method being carried out in the plasma device of any one of claims 1-16, the method comprising: connecting an outer electrode (4) and an inner electrode of the plasma device (3) One of them is connected to the high-voltage power supply, the other is grounded, and dielectric barrier discharge is performed, and the raw material gas containing hydrogen sulfide is discharged from the first inlet (11) of the first cavity (1) of the plasma equipment. The hydrogen sulfide is introduced into the first cavity (1) for the decomposition reaction of hydrogen sulfide, and the stream obtained after the decomposition is drawn out from the first outlet, and continues from the second inlet (21) to the second cavity ( 2) A heat conducting medium is introduced and the heat conducting medium is led out from the second outlet (22) to control the temperature of the first cavity (1) of the plasma device. 18. The method according to claim 17, wherein the condition of the dielectric barrier discharge comprises: the discharge voltage is 2kV-80kV, preferably 5kV-30kV, more preferably 5kV-20kV, still more preferably 5kV-15kV; The discharge frequency is 200-30000Hz, preferably 500-15000Hz, more preferably 500-13000Hz; The conditions of the decomposition reaction include: the reaction temperature is 0-800°C, preferably 40-500°C, more preferably 119-444.6°C, the reaction pressure is 0-0.6MPa, preferably 0-0.3MPa, The residence time of the raw material gas containing hydrogen sulfide in the discharge region of the plasma equipment is 1×10 ^-5 to 120s, preferably 2×10 ^-5 to 60s. 19. The method according to claim 17 or 18, wherein the decomposition reaction of the hydrogen sulfide is carried out in the presence of a carrier gas selected from nitrogen, hydrogen, helium, argon, water vapor, carbon monoxide, At least one of carbon dioxide, methane, ethane and propane, preferably the carrier gas is selected from at least one of hydrogen, argon, helium and nitrogen.

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