CN110127627B - Low temperature plasma system for decomposing hydrogen sulfide and method for decomposing hydrogen sulfide - Google Patents

Low temperature plasma system for decomposing hydrogen sulfide and method for decomposing hydrogen sulfide Download PDF

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Publication number
CN110127627B
CN110127627B CN201810136800.4A CN201810136800A CN110127627B CN 110127627 B CN110127627 B CN 110127627B CN 201810136800 A CN201810136800 A CN 201810136800A CN 110127627 B CN110127627 B CN 110127627B
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hydrogen sulfide
temperature plasma
low temperature
reactor
gas
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CN110127627A (en
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石宁
张婧
朱云峰
孙峰
任君朋
徐伟
张铁
李亚辉
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China Petroleum and Chemical Corp
Sinopec Qingdao Safety Engineering Institute
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China Petroleum and Chemical Corp
Sinopec Qingdao Safety Engineering Institute
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/02—Preparation of sulfur; Purification
    • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B17/00—Sulfur; Compounds thereof
    • C01B17/02—Preparation of sulfur; Purification
    • C01B17/04—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides
    • C01B17/0404—Preparation of sulfur; Purification from gaseous sulfur compounds including gaseous sulfides by processes comprising a dry catalytic conversion of hydrogen sulfide-containing gases, e.g. the Claus process
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/04—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by decomposition of inorganic compounds, e.g. ammonia
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis

Abstract

The invention relates to plasmaThe daughter chemistry field discloses a low-temperature plasma system for decomposing hydrogen sulfide and a method for decomposing hydrogen sulfide, the system comprises a gas supply-distribution unit, a plasma reaction unit and a product separation unit which are sequentially connected through pipelines, the plasma reaction unit comprises a low-temperature plasma reactor and a plasma power supply, and the reactor comprises: inner cylinder, outer cylinder, central electrode in the inner cylinder, barrier medium surrounding the side wall of the inner cylinder or wrapping the outer surface of the central electrode or forming the side wall of the inner cylinder, grounding electrode, and thickness L of discharge air gap1And length L of discharge region2The proportion relation between the components is as follows: l is1：L21: (0.5-6000). The low-temperature plasma device for decomposing hydrogen sulfide and the method for decomposing hydrogen sulfide provided by the invention can improve the conversion rate of hydrogen sulfide.

Description

Low temperature plasma system for decomposing hydrogen sulfide and method for decomposing hydrogen sulfide
Technical Field
The invention relates to the field of plasma chemistry, in particular to a low-temperature plasma system for decomposing hydrogen sulfide and a method for decomposing hydrogen sulfide.
Background
Hydrogen sulfide (H)2S) is a highly toxic and malodorous acidic gas, which not only can cause corrosion of materials such as metal, but also can easily cause catalyst poisoning and inactivation in chemical production; in addition, hydrogen sulfide can also harm human health and cause environmental pollution. Therefore, in the case of performing a detoxification treatment of a large amount of hydrogen sulfide gas generated in industrial fields such as petroleum, natural gas, coal, and mineral processing, a solution is urgently needed in view of process requirements, equipment maintenance, environmental requirements, and the like.
Currently, the hydrogen sulfide is treated by the Claus process, which partially oxidizes hydrogen sulfide to produce sulfur and water. Although the method solves the problem of harmlessness of hydrogen sulfide, a large amount of hydrogen resources are lost.
With the increase of the processing amount of high-sulfur crude oil in China, the amount of the hydrogen sulfide-containing acidic tail gas which is a byproduct of an oil refining hydrofining unit is increased year by year, and the amount of hydrogen required by hydrofining is increased; in addition, hydrogen is used as a main raw material in chemical process such as oil hydrocracking, low-carbon alcohol synthesis, synthetic ammonia and the like, and the demand amount is also considerable. Therefore, the direct decomposition of the hydrogen sulfide is an ideal hydrogen sulfide resource utilization technical route, the hydrogen sulfide is harmless, the hydrogen and the elemental sulfur can be produced, the cyclic utilization of the hydrogen resource in the petroleum processing process can be realized, and the emission of a large amount of carbon dioxide brought by the conventional hydrocarbon reforming hydrogen production can be reduced.
At present, the hydrogen sulfide decomposition method mainly comprises the following steps: high temperature decomposition, electrochemical, photocatalytic, and low temperature plasma methods. Among the aforementioned methods, the pyrolysis method is relatively mature in industrial technology, but the thermal decomposition of hydrogen sulfide strongly depends on the reaction temperature and is limited by the thermodynamic equilibrium, and the conversion rate of hydrogen sulfide is only 20% even if the reaction temperature is 1000 ℃ or higher. In addition, the high temperature conditions place high demands on reactor materials, which also increases operating costs. In addition, since the thermal decomposition conversion of hydrogen sulfide is low, a large amount of hydrogen sulfide gas needs to be separated from the tail gas and circulated in the system, thereby reducing the efficiency of the apparatus and increasing the energy consumption, which all bring difficulties to large-scale industrial application thereof. Although the adoption of the membrane technology can effectively separate products, thereby breaking balance limitation and improving the conversion rate of hydrogen sulfide, the thermal decomposition temperature often exceeds the limit heat-resistant temperature of the membrane, so that the structure of the membrane material is damaged. The electrochemical method has the defects of multiple operation steps, serious equipment corrosion, poor reaction stability, low efficiency and the like. The photocatalytic method for decomposing hydrogen sulfide mainly refers to the research of photocatalytic water decomposition, and the research focuses on the aspects of developing high-efficiency semiconductor photocatalysts and the like. The method for decomposing the hydrogen sulfide by utilizing the solar energy has the advantages of low energy consumption, mild reaction conditions, simple operation and the like, and is a relatively economic method. However, this method has problems such as a small treatment amount, 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 volume, high energy efficiency and the like, and the involved reaction has high controllability and can be flexibly applied under the conditions of small treatment capacity and difficult centralized treatment. In addition, the hydrogen sulfide decomposition device has the characteristics of high energy density and shortened reaction time, can realize effective decomposition of hydrogen sulfide at a lower temperature, and is suitable for occasions with different scales, dispersed layouts and variable production conditions. Besides, the low-temperature plasma method recovers hydrogen resources while recovering sulfur, and can realize resource utilization of hydrogen sulfide.
At present, researchers at home and abroad carry out extensive research on the technology of decomposing hydrogen sulfide by low-temperature plasma, and the used discharge forms mainly comprise glow discharge, corona discharge, sliding arc discharge, microwave plasma, radio frequency plasma, dielectric barrier discharge and the like.
Document International journal of hydrogen energy, 2012, 37: 1335-1347, decomposing hydrogen sulfide by contracting normal glow discharge, obtaining hydrogen sulfide with the lowest decomposition energy consumption of 2.35eV/H under the conditions of pressure of 0.02Mpa and temperature of 2000-4000K2And S. However, the reaction temperature is high, the pressure is low, and the conditions are harsh and are not easy to realize.
Document International journal of hydrogen energy, 2012, 37: 10010-.
Document "Chemical Engineering Science, 2009, 64 (23): 4826-4834 application of pulsed corona discharge to H2Research on hydrogen and sulfur preparation by S decomposition, a reactor adopts a wire tube structure, and pulse forming capacitance, discharge voltage and pulse frequency are considered to be H under the condition of fixed power of 100W2S conversion and decomposition energy efficiency. The result shows that under the condition of certain power, the low pulse forming capacitance, the low discharge voltage and the high pulse frequency are beneficial to obtaining high H2S, decomposing energy efficiency; in addition, with Ar and N2As equilibrium gas phase ratio, with Ar-N2Higher H can be obtained when the mixed gas is used as balance gas2Conversion of S in Ar/N2/H2H obtained when S volume fraction is 46%/46%/8%, discharge power is 60W, and pulse forming capacitance is 720pF2The minimum energy consumption for S decomposition is 4.9eV/H2S, but then H2The S conversion rate is only about 30%, and in addition, the flow rate of the reaction system is only 1.18 × 10-4SCMs-1The reaction effect of low flow, low concentration and low conversion rate has no practical significance in industrial production.
Document Journal of applied physics, 1998, 84 (3): 1215-2S decomposition reaction was studied by reacting H2S is diluted by air to the concentration of 0-100 ppm, and the gas flow rate, the size of a reaction cavity and the frequency are examined to H under the condition that the total gas flow rate is 0-100L/min2Influence of S decomposition reaction. The experimental result shows that the low gas flow rate, the small disc space and the low frequency are beneficial to obtaining higher H2S conversion, H obtained under optimized discharge conditions2S conversion rate can reach 75-80%, but H2The energy consumption of S decomposition is as high as 500eV/H2S, the reaction effect with low concentration and high energy consumption has no industrial application prospect.
Dielectric barrier discharges can generally be generated at atmospheric pressure and the discharge temperature is low. In addition, the increase of the discharge current is limited due to the existence of the medium, so that the gas is prevented from being completely broken down to form sparks or electric arcs, the generation of large-size and stable plasmas is facilitated, and the method has a good industrial application prospect.
Literature "Plasma chemistry and Plasma processing", 1992, 12 (3): 275-285 investigated H using a modified ozone generator2S is in the range of 130-560 ℃, and the reaction temperature and H are studied2S feed concentration, injection power and addition of H2、Ar、N2Pair H2The influence of S conversion rate and energy efficiency, and experiments show that the addition of Ar can promote H2Decomposing S at a total flow rate of 50-100 mL/min and H2The conversion rate is 0.5-12% under the condition that the concentration of S is 20-100%, and the minimum energy consumption for producing hydrogen is about 0.75mol/kWh (50 eV/H)2) However, this process still has the disadvantages of low conversion and high energy consumption.
CN102408095A uses medium to block discharge and light catalyst to decompose hydrogen sulfide, and its method is to pack solid catalyst with light catalytic activity in plasma zone, however, this method has the disadvantage that sulfur produced by hydrogen sulfide decomposition will deposit under catalyst bed.
Document International Journal of Energy Research, 2013, 37 (11): 1280-1286-adding Al2O3，MoOx/Al2O3，CoOx/Al2O3And NiO/Al2O3Catalyst is filled in discharge region, and H is carried out by using dielectric barrier discharge and catalyst2And (5) S decomposition research. The reaction result shows that MoOx/Al2O3And CoOx/Al2O3The catalyst has better effect; wherein when filled with MoOx/Al2O3Catalyst in H2Total S/Ar flow rate 150mL/min, H2H is obtained when the S concentration is 5 volume percent, the injection specific energy SIE is 0.92kJ/L and the catalyst filling length is 10 percent of the bed layer2The highest conversion of S is about 48%. However, the concentration of hydrogen sulfide is low in the reaction process, and sulfur generated by decomposition is deposited onInside the reactor, the catalyst activity decreases and the discharge stability decreases with time, resulting in a gradual decrease in the conversion of hydrogen sulfide.
CN103204466A discloses a temperature-controlled hydrogen sulfide decomposition device and method, the device is characterized in that a central electrode is made of metal, a grounding electrode is made of temperature-controlled circulating liquid, and the hydrogen sulfide decomposition process can be continuously and stably carried out through temperature control of a liquid grounding electrode. In addition, CN103204467A discloses a device and a method for preparing hydrogen by continuously and stably decomposing hydrogen sulfide, which is characterized in that a central electrode is made of metal, a ground electrode is used as temperature-controllable circulating liquid, temperature control is performed through a liquid ground electrode, raw material is fed in a circumferential direction and reversely passes through a discharge area in a spiral mode along an axial direction, so that generated sulfur is timely and centrifugally separated. However, in order to ensure that the hydrogen sulfide is decomposed as sufficiently as possible in the methods disclosed in CN103204466A and CN103204467A, it is necessary to control the flow rate of the hydrogen sulfide so that the residence time of the hydrogen sulfide 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, and since the current prior art cannot provide a more powerful power source, the methods disclosed in CN103204466A and CN103204467A can only achieve the highest conversion rate of the hydrogen sulfide of about 20% even if the residence time of the hydrogen sulfide is 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, and when the highest conversion rate of the hydrogen sulfide reaches about 20%, the energy consumption of the decomposition reaction of the hydrogen sulfide is considerably high and is not suitable for large-scale industrial applications. Further, the methods disclosed in CN103204466A and CN103204467A have the drawback that the kinds of the liquid-applicable ground electrodes are very few, and the disclosed salt solutions and the like can generally only maintain the temperature of the reactor at 100 ℃ or lower, whereas elemental sulfur is generally solid at 100 ℃ or lower, which is likely to cause the reactor to be clogged.
Disclosure of Invention
The invention aims to overcome the defects of low hydrogen sulfide conversion rate and unstable conversion rate in the hydrogen sulfide decomposition process provided by the prior art, and provides a novel low-temperature plasma system for decomposing hydrogen sulfide and a method for decomposing hydrogen sulfide.
In order to achieve the above object, a first aspect of the present invention provides a low temperature plasma system for decomposing hydrogen sulfide, the system comprising a gas supply-distribution unit, a plasma reaction unit and a product separation unit connected in sequence by pipelines, the plasma reaction unit comprising a low temperature plasma reactor and a plasma power supply, the reactor comprising:
the inner cylinder is provided with a reactor inlet and a product outlet respectively;
the outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively arranged on the outer cylinder;
a central electrode disposed in the inner barrel;
the blocking medium is arranged on the inner side wall of the inner barrel in a surrounding mode or is arranged on the outer surface of the central electrode in a wrapping mode, or the blocking medium forms at least part of the side wall of the inner barrel so that at least part of the blocking medium surrounds the central electrode;
the grounding electrode is made of a solid conductive material and is arranged on the outer side wall of the inner barrel in a surrounding mode, or the grounding electrode forms at least part of the side wall of the inner barrel, and the blocking medium is arranged at a position enabling a discharge area between the central electrode and the grounding electrode to be separated by the blocking medium;
wherein a distance between an outer sidewall of the center electrode and an inner sidewall of the ground electrode is D1, and a thickness of the blocking medium is D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
A second aspect of the invention provides a method of decomposing hydrogen sulfide, the method being carried out in a low temperature plasma system as described in the first aspect of the invention, the method comprising:
raw material gas containing hydrogen sulfide from the gas supply-distribution unit enters the plasma reaction unit through a pipeline;
in the presence of a plasma discharge field generated by a low-temperature plasma reactor and a plasma power supply in the plasma reaction unit, the feed gas enters an inner cylinder of the low-temperature plasma reactor through an inlet of the reactor to carry out hydrogen sulfide decomposition reaction, and a gas-phase substance and a liquid-phase elemental sulfur obtained after the reaction are led out of the low-temperature plasma reactor through a product outlet;
gas-phase substances and liquid-phase elemental sulfur from the low-temperature plasma reactor enter a product separation unit to be separated so as to respectively obtain elemental sulfur, hydrogen and tail gas containing hydrogen sulfide;
optionally introducing the hydrogen sulfide-containing tail gas obtained in the product separation unit into a hydrogen sulfide recycling unit for separation to obtain hydrogen sulfide recycled to the gas supply-distribution unit or the plasma reaction unit.
The low-temperature plasma system for decomposing hydrogen sulfide provided by the invention can be used for plasma decomposition of hydrogen sulfide, and the system can generate uniform and efficient dielectric barrier discharge so as to directly decompose hydrogen sulfide to generate hydrogen and sulfur.
The low-temperature plasma system for decomposing hydrogen sulfide and the method for decomposing hydrogen sulfide provided by the invention can obtain high-purity hydrogen and have high conversion rate of hydrogen sulfide.
The low-temperature plasma unit for decomposing hydrogen sulfide provided by the invention is jacket type dielectric barrier discharge reaction equipment with a coaxial structure, the basic structure of the low-temperature plasma unit mainly comprises a central electrode, a solid grounding electrode, a barrier medium and the like, and the sleeve type structure can enable a heat-conducting medium to circularly heat or cool a discharge reactor, so that flexible temperature control of a discharge area is realized. In particular, the present invention is achieved by controlling L1And L2The proportion relation is as follows: l is1：L21: (0.5-6000) (D1 is the distance between the outer side wall of the center electrode and the inner side wall of the grounding electrode, D1Is the barrier mediumAnd L is1＝d1-D1) Compared with the prior art, the device provided by the invention can obviously improve the conversion rate of hydrogen sulfide and reduce the decomposition energy consumption.
In addition, the method for decomposing hydrogen sulfide provided by the invention can realize continuous and stable operation of the hydrogen sulfide decomposition process under the condition of obviously higher hydrogen sulfide conversion rate, and the system can realize long-period operation. In addition, the method for decomposing the hydrogen sulfide provided by the invention can also be used for the hydrogen sulfide treatment process with large flow and various concentrations.
Drawings
FIG. 1 is a schematic structural diagram of a preferred embodiment of a low-temperature plasma reactor in a low-temperature plasma system for decomposing hydrogen sulfide provided by the present invention;
FIG. 2 is a schematic structural diagram of another preferred embodiment of a low-temperature plasma reactor in a low-temperature plasma system for decomposing hydrogen sulfide provided by the present invention;
FIG. 3 is a flow diagram of a low temperature plasma system for decomposing hydrogen sulfide in accordance with the present invention.
Description of the reference numerals
1. Inner cylinder 2, outer cylinder
11. Reactor inlet 21, heat transfer medium inlet
12. Gas product outlet 22 and heat-conducting medium outlet
13. Liquid product outlet
3. Center electrode
4. Grounding electrode
5. Grounding wire
6. Barrier dielectric
A. Air supply-distribution unit A1 and mixer
B. Plasma reaction unit B1, low temperature plasma reactor
C. Product separation unit and hydrogen sulfide recycle unit
C1, gas-liquid separator C2, particulate purifier
C3, amine liquid absorption tower C4 and analysis tower
C5, carrier-gas separator C6, sulfur storage
Detailed Description
The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a low temperature plasma system for decomposing hydrogen sulfide, the system comprising a gas supply-distribution unit, a plasma reaction unit and a product separation unit connected in sequence by pipelines, the plasma reaction unit comprising a low temperature plasma reactor and a plasma power supply, the reactor comprising:
the inner cylinder is provided with a reactor inlet and a product outlet respectively;
the outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively arranged on the outer cylinder;
a central electrode disposed in the inner barrel;
the blocking medium is arranged on the inner side wall of the inner barrel in a surrounding mode or is arranged on the outer surface of the central electrode in a wrapping mode, or the blocking medium forms at least part of the side wall of the inner barrel so that at least part of the blocking medium surrounds the central electrode;
the grounding electrode is made of a solid conductive material and is arranged on the outer side wall of the inner barrel in a surrounding mode, or the grounding electrode forms at least part of the side wall of the inner barrel, and the blocking medium is arranged at a position enabling a discharge area between the central electrode and the grounding electrode to be separated by the blocking medium;
wherein a distance between an outer sidewall of the center electrode and an inner sidewall of the ground electrode is D1, and a thickness of the blocking medium is D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
In the present invention, in order to further increase the conversion rate of hydrogen sulfide, it is preferable that L is in the low-temperature plasma reactor1：L2＝1：(2～3000)。
The differences between the "side wall" and the "outer side wall" and the "inner side wall" of the present invention are: "outer sidewall" and "inner sidewall" refer to the "sidewall" outer and inner surfaces, respectively.
In particular, the inventors of the present invention found that controlling L1：L2Is in the aforementioned range of the present invention, and L1And the thickness D of the barrier medium1The proportion relation is as follows: (0.05-100): 1, particularly preferably L1：D1(0.1-30): 1, the system of the invention can realize higher decomposition conversion rate of the hydrogen sulfide under relatively lower decomposition energy consumption.
In the low-temperature plasma reactor, the central electrode is preferably disposed at the axial center of the inner cylinder, thereby facilitating uniform discharge of the system of the present invention. And the central electrode arranged at the position of the shaft core is connected with the plasma power supply.
In the low-temperature plasma system for decomposing hydrogen sulfide, particularly in the low-temperature plasma reactor of the plasma reaction unit, the jacket cylinder type structural design can ensure that the heat-conducting medium circularly flows in the shell layer, the whole reaction unit can be maintained in a certain temperature range while the discharge intensity is ensured, the generated sulfur flows out of the reaction unit in a liquid state, the sulfur generated by decomposing hydrogen sulfide can be effectively prevented from being solidified, and the decomposition process can continuously and stably realize long-period operation while the higher conversion rate is achieved.
According to a first preferred embodiment, in the low temperature plasma reactor, the blocking medium forms at least part of the sidewall of the inner barrel such that at least part of the blocking medium surrounds the central electrode; and the grounding electrode is arranged on the outer side wall of the inner cylinder in a surrounding manner.
In the aforementioned first preferred embodiment, it is preferred that the barrier medium forms all of the side wall of the inner barrel.
According to a second preferred embodiment, in the low-temperature plasma reactor, the blocking medium is wrapped and arranged on the outer surface of the central electrode, and the grounding electrode is arranged on the inner side wall of the inner cylinder in a surrounding mode. The barrier medium of the present invention may be fixed to the outer surface of the center electrode in any manner that allows for fixation, or the barrier medium may be applied to the outer surface of the center electrode in the form of a coating.
The aforementioned 2 positions of the barrier dielectric and the grounding electrode are beneficial to the high-power uniform discharge of the reaction system of the present invention. The fixing method of the barrier medium and the ground electrode to each other or the fixing method of the barrier medium, the ground electrode and the inner cylindrical wall is not particularly required in the present invention, and a person skilled in the art can select an appropriate fixing form according to the materials forming the barrier medium, the inner cylindrical wall and the ground electrode, and the present invention is not particularly limited thereto.
Preferably, in the low-temperature plasma reactor, the material forming the barrier medium is an electrically insulating material, and more preferably, the material forming the barrier medium is selected from at least one of glass, ceramic, enamel, polytetrafluoroethylene, and mica. The glass can be quartz glass or hard glass; the material forming the barrier medium can also be other metal and non-metal composite materials with high-voltage electric insulation design, and the like. The ceramic may be an alumina ceramic.
Preferably, the low-temperature plasma reactor further comprises a grounding wire, the grounding wire is arranged on the outer side wall of the outer barrel, and one end of the grounding wire is electrically connected with the grounding electrode.
Preferably, in the low-temperature plasma reactor, the reactor inlet is arranged at the upper part of the inner cylinder, and the product outlet is arranged at the lower part and/or the bottom of the inner cylinder.
According to a preferred embodiment, in the low-temperature plasma reactor, the product outlet includes a gaseous product outlet and a liquid product outlet, and the gaseous product outlet is disposed at a lower portion of the inner cylinder, and the liquid product outlet is disposed at a bottom portion of the inner cylinder.
In the low-temperature plasma reactor, the ratio of the inner diameter of the inner cylinder to the aperture of the product outlet may be (0.1 to 100): 1.
in the low-temperature plasma reactor, the ratio of the pore diameter of the reactor inlet to the pore diameter of the product outlet may be (0.1 to 120): 1.
in the low-temperature plasma reactor, the ratio of the length of the inner cylinder to the inner diameter of the inner cylinder may be (0.5-500): 1.
preferably, in the low-temperature plasma reactor, the gas product outlet is arranged below the discharge region, and the gas product outlet is arranged at a position corresponding to the height H of the bottom of the inner cylinder1And the length L of the discharge region2The proportion relation between the components is as follows: h1：L21: (0.05 to 25000); preferably H1：L21: (0.1 to 10000); more preferably H1：L2＝1：(0.5～1000)。
Preferably, in the low-temperature plasma reactor, the heat transfer medium inlet and the heat transfer medium outlet are disposed at a lower portion and an upper portion of the outer tub, respectively.
In the present invention, in the low-temperature plasma reactor, there is no particular limitation on the inner diameter ratio between the inner cylinder, in which the hydrogen sulfide decomposition reaction mainly occurs, and the outer cylinder, which mainly serves to provide a desired temperature to the inner cylinder, and therefore, those skilled in the art can adjust and select an appropriate inner diameter ratio between the inner cylinder and the outer cylinder according to the purpose.
The reactor inlet of the present invention may be positioned such that the feed gas entering the inner drum is parallel to the inner diameter of the inner drum or at an angle, for example, may be tangentially positioned.
The inner diameters of the present invention each represent a diameter.
Preferably, the material forming the ground electrode is selected from a graphite tube, a metal foil or a metal mesh. The solid grounding electrode of the invention generates larger micro discharge current under the condition of certain injection power, and is more beneficial to the broken bond decomposition reaction of hydrogen sulfide. The metal tube and the metal foil in the material forming the ground electrode may include an elemental metal tube, an elemental metal foil, an alloy metal tube, and an alloy metal foil. The inventor of the invention finds that when the solid conductive material is used as the grounding electrode and is arranged on the inner wall or the outer wall of the inner cylinder in a surrounding mode, the conversion rate of hydrogen sulfide can be improved more remarkably when the system provided by the invention is used for carrying out hydrogen sulfide decomposition reaction.
The material forming the central electrode is a conductive material, and preferably, the material forming the central electrode is selected from at least one of a graphite tube, a metal rod, a metal tube, and a graphite rod. The metal rod and the metal pipe can comprise an elemental metal rod, an alloy metal rod, an elemental metal pipe and an alloy metal pipe. The material forming the center electrode of the present invention may be other rod-shaped or tubular materials having conductive properties.
The invention can lead the heat-conducting medium to be introduced into the area between the outer side wall of the inner cylinder and the inner side wall of the outer cylinder of the low-temperature plasma reactor, so that the temperature of the low-temperature plasma reactor with the jacket structure is maintained between 119-444.6 ℃ for example, and the sulfur generated by the decomposition of the hydrogen sulfide can be ensured to flow out of the discharge area in a liquid state.
The low-temperature plasma reactor can be filled with a catalyst capable of catalyzing hydrogen sulfide to be decomposed into elemental sulfur and hydrogen, and the catalyst is preferably filled in an inner cylinder of the low-temperature plasma reactor. The present invention has no particular requirement on the loading volume and the loading type of the catalyst, and the type of the catalyst may be, for example, any one or more of the catalysts disclosed in CN102408095A, CN101590410A, and CN 103495427A.
The low-temperature plasma reactor provided by the invention has no particular limitation on the conditions of the decomposition reaction involved in decomposing hydrogen sulfide, and can be used for decomposing hydrogen sulfide by various conditions involved in a plasma decomposition method conventionally adopted in the field.
The low-temperature plasma reactor provided by the invention has no particular limitation on the concentration of hydrogen sulfide in the gas at the inlet of the reactor, and for example, the concentration of hydrogen sulfide in the gas can be 0.01-100% by volume.
In the present invention, the material forming the outer cylinder is not particularly limited as long as the material forming the outer cylinder can withstand the set temperature of the heat transfer medium.
The plasma reaction unit of the present invention may include 1 or 2 or more low-temperature plasma reactors.
The following provides preferred embodiments of the low temperature plasma reactor of the present invention for decomposing hydrogen sulfide as described above:
nitrogen gas was passed into the inner barrel of the low temperature plasma reactor from the reactor inlet to purge the discharge zone of air, and the gas was withdrawn from the product outlet. Meanwhile, heat-conducting media are led into the outer barrel from the heat-conducting medium inlet, and the led-in heat-conducting media are led out from the heat-conducting medium outlet. The temperature of the heat transfer medium is maintained at the temperature required for the system reaction. Then introducing raw material gas containing hydrogen sulfide into the inner cylinder of the low-temperature plasma reactor from the inlet of the reactor, switching on a high-voltage power supply after the raw material gas flow is stable, and forming a plasma discharge field between the central electrode and the grounding electrode by adjusting voltage and frequency. The hydrogen sulfide gas is ionized in the discharge area and decomposed into hydrogen and elemental sulfur, and the elemental sulfur generated by discharge slowly flows down along the inner cylinder wall and flows out from the liquid product outlet. The gas after reaction mainly flows out from the gas product outlet.
Preferably, the low-temperature plasma system for decomposing hydrogen sulfide of the present invention further comprises a hydrogen sulfide recycling unit for recovering hydrogen sulfide from the gas phase substance containing hydrogen sulfide obtained in the product separation unit and recycling the resulting hydrogen sulfide to the gas supply-distribution unit or the plasma reaction unit.
Preferably, the hydrogen sulfide circulation unit includes an amine liquid absorption tower for absorbing hydrogen sulfide and a desorption tower for desorbing hydrogen sulfide.
Preferably, in the low temperature plasma system for decomposing hydrogen sulfide of the present invention, the product separation unit comprises a gas-liquid separator, and optionally a particulate purifier and/or a carrier gas separator.
The hydrogen sulfide recycling unit of the present invention may be attached to the product separation unit, and preferably, the product separation unit and the hydrogen sulfide recycling unit are connected in a manner including: the gas-liquid separator in the product separation unit is connected with the plasma reaction unit through a pipeline, so that gas-phase products and liquid-phase sulfur elementary substances from the plasma reaction unit can enter the gas-liquid separator to be separated so as to obtain first gaseous substances and liquid sulfur respectively, the first gaseous substances are optionally introduced into a particle purifier to be further separated so as to obtain residual solid sulfur and second gaseous substances, and the liquid sulfur and the residual solid sulfur can both be led out of the low-temperature plasma system for decomposing hydrogen sulfide. Further, the hydrogen sulfide circulation unit is connected with the product separation unit through a pipeline, so that the second gaseous substance can enter an amine liquid absorption tower in the hydrogen sulfide circulation unit through a pipeline to respectively obtain hydrogen sulfide removing gas and hydrogen sulfide containing liquid, the hydrogen sulfide removing gas optionally enters a carrier gas separator through a pipeline to separate carrier gas possibly existing in the hydrogen sulfide removing gas, and a hydrogen-containing crude product is obtained, and the hydrogen-containing crude product can be further purified as required; and the liquid containing hydrogen sulfide is introduced into a desorption tower through a pipeline to desorb hydrogen sulfide gas so as to be used for the gas supply-distribution unit or the plasma reaction unit.
Preferably, the gas supply-distribution unit of the present invention includes a device capable of adjusting the volume ratio of the hydrogen sulfide-containing gas to the carrier gas, that is, the raw gas with a suitable gas type and hydrogen sulfide content can be obtained by the gas supply-distribution unit to enter the plasma reaction unit. For example, the gas supply and distribution unit may include a mixer, so that the gas containing hydrogen sulfide is mixed with the carrier gas and then enters the plasma reaction unit as a raw material gas.
As mentioned above, a second aspect of the present invention provides a method of decomposing hydrogen sulfide, the method being carried out in the low temperature plasma system according to the aforementioned first aspect of the present invention, the method comprising:
raw material gas containing hydrogen sulfide from the gas supply-distribution unit enters the plasma reaction unit through a pipeline;
in the presence of a plasma discharge field generated by a low-temperature plasma reactor and a plasma power supply in the plasma reaction unit, the feed gas enters an inner cylinder of the low-temperature plasma reactor through an inlet of the reactor to carry out hydrogen sulfide decomposition reaction, and a gas-phase substance and a liquid-phase elemental sulfur obtained after the reaction are led out of the low-temperature plasma reactor through a product outlet;
gas-phase substances and liquid-phase elemental sulfur from the low-temperature plasma reactor enter a product separation unit to be separated so as to respectively obtain elemental sulfur, hydrogen and tail gas containing hydrogen sulfide;
optionally introducing the hydrogen sulfide-containing tail gas obtained in the product separation unit into a hydrogen sulfide recycling unit for separation to obtain hydrogen sulfide recycled to the gas supply-distribution unit or the plasma reaction unit.
Preferably, in the method of the present invention, the gas-phase substance and the liquid-phase elemental sulfur from the low-temperature plasma reactor enter the gas-liquid separator of the product separation unit to be separated to obtain a first gas-phase substance and liquid sulfur, respectively, and the first gas-phase substance is optionally introduced into the particulate purifier optionally contained in the product separation unit to be further separated to obtain residual solid sulfur and a second gas-phase substance. Further, the second gaseous substance enters an amine liquid absorption tower in the hydrogen sulfide circulation unit to respectively obtain hydrogen sulfide removing gas and hydrogen sulfide containing liquid, and optionally the hydrogen sulfide removing gas enters a carrier gas separator optionally contained in the product separation unit to separate carrier gas possibly existing in the hydrogen sulfide removing gas so as to obtain a crude product containing hydrogen. The hydrogen sulfide-containing liquid obtained in the invention is introduced into a desorption tower in the hydrogen sulfide circulation unit to desorb hydrogen sulfide gas, and the hydrogen sulfide obtained by desorption is circulated back to the gas supply-distribution unit or the plasma reaction unit.
In the present invention, the raw material gas preferably contains hydrogen sulfide and a carrier gas, and the type of the carrier gas is not particularly limited, and may be hydrogen, nitrogen, argon, helium, carbon dioxide, carbon monoxide, air, gaseous hydrocarbons, or the like. The source of the hydrogen sulfide gas in the raw material gas of the present invention may be pure hydrogen sulfide gas, or industrial waste gas obtained in industrial production and containing hydrogen sulfide and other gases, and when the raw material gas contains a carrier gas, it is preferable to control the volume content of the carrier gas in the raw material gas by means of a valve, a flow meter, and the like.
The hydrogen-containing crude product of the present invention can be further purified as necessary. The method for further purifying the crude hydrogen-containing product is not particularly limited in the present invention, and for example, the crude hydrogen-containing product may be introduced into an alkaline solution containing sodium hydroxide.
The liquid sulfur and the residual solid sulfur obtained in the process of the present invention are used for recovery.
The structure of a preferred embodiment of the low temperature plasma reactor of the present invention is provided below in conjunction with fig. 1, specifically:
the reactor has a coaxial jacket-type structure, and the reactor comprises:
the reactor comprises an inner cylinder 1, wherein a reactor inlet 11 and a product outlet are respectively arranged on the inner cylinder 1;
the outer cylinder 2 is nested outside the inner cylinder 1, and a heat-conducting medium inlet 21 and a heat-conducting medium outlet 22 are respectively arranged on the outer cylinder 2;
a central electrode 3, the central electrode 3 being disposed in the inner barrel 1;
a grounding electrode 4, wherein the material for forming the grounding electrode 4 is a solid conductive material, and the grounding electrode 4 is arranged on the outer side wall of the inner cylinder 1;
wherein at least part of the cylindrical structure of the inner cylinder 1 is formed by a barrier medium, so that at least part of the barrier medium surrounds the central electrode 3, the distance between the outer side wall of the central electrode 3 and the inner side wall of the grounding electrode is D1, and the thickness of the barrier medium 6 is D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
The structure of another preferred embodiment of the low temperature plasma reactor of the present invention is provided below in conjunction with fig. 2, specifically:
the reactor has a coaxial jacket-type structure, and the reactor comprises:
the reactor comprises an inner cylinder 1, wherein a reactor inlet 11 and a product outlet are respectively arranged on the inner cylinder 1;
the outer cylinder 2 is nested outside the inner cylinder 1, and a heat-conducting medium inlet 21 and a heat-conducting medium outlet 22 are respectively arranged on the outer cylinder 2;
a central electrode 3, the central electrode 3 being disposed in the inner barrel 1;
the grounding electrode 4 is made of a solid conductive material, and the grounding electrode 4 is arranged on the inner side wall of the inner barrel 1 in a surrounding mode;
the barrier medium 6 is arranged on at least part of the outer surface of the central electrode 3, so that the barrier medium 6 is wrapped on the outer surface of the central electrode 3 at least partially extending into the inner barrel 1;
wherein, between the outer side wall of the center electrode 3 and the inner side wall of the grounding electrodeHas a distance D1, the barrier medium 6 has a thickness D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
In fig. 1 and 2, it is preferable that the low-temperature plasma reactor of the present invention further has the following features:
preferably, the reactor further comprises a grounding wire 5, wherein the grounding wire 5 is arranged on the outer wall of the outer cylinder 2, and one end of the grounding wire 5 is connected with the grounding electrode 4.
Preferably, the reactor inlet 11 is disposed at the upper portion of the inner drum 1, and the product outlet is disposed at the lower portion and/or bottom of the inner drum 1.
Preferably, the product outlets include a gaseous product outlet 12 and a liquid product outlet 13, and the gaseous product outlet 12 is disposed at the lower portion of the inner drum 1, and the liquid product outlet 13 is disposed at the bottom of the inner drum 1.
Preferably, the gas product outlet 12 is arranged below the discharge area, and the gas product outlet 12 is arranged at a height H relative to the bottom of the inner cylinder 11And the length L of the discharge region2The proportion relation between the components is as follows: h1：L21: (0.05 to 25000); preferably H1：L21: (0.1 to 10000); more preferably H1：L2＝1：(0.5～1000)。
Preferably, the heat transfer medium inlet 21 and the heat transfer medium outlet 22 are disposed at a lower portion and an upper portion of the outer tub 2, respectively.
The flow of a preferred embodiment of the hydrogen sulfide decomposing low temperature plasma system of the present invention is provided below in conjunction with FIG. 3, specifically:
the low-temperature plasma system for decomposing hydrogen sulfide comprises a gas supply-distribution unit A, a plasma reaction unit B, a product separation unit and a hydrogen sulfide circulation unit C which are sequentially connected through pipelines, wherein the plasma reaction unit comprises a low-temperature plasma reactor B1 and a plasma power supply (not shown). Preferably, the low temperature plasma reactor B1 has the structure shown in fig. 1 or fig. 2. Preferably, the plasma reaction unit B includes a plurality of, for example, 4 low-temperature plasma reactors B1.
Preferably, the gas supply-distribution unit a includes a mixer a1, the mixer a1 is configured to mix hydrogen sulfide gas with, for example, carrier gas to form a raw material gas as required, and introduce the obtained raw material gas into the low-temperature plasma reactor B1 in the plasma reaction unit B to perform a hydrogen sulfide decomposition reaction, the reacted product enters the product separation unit and the hydrogen sulfide circulation unit C, for example, the reacted product enters the gas-liquid separator C1 to perform gas-liquid separation, the liquid sulfur obtained after the gas-liquid separation enters the sulfur storage C6, the first gaseous substance obtained after the gas-liquid separation enters the particulate purifier C2 to perform further separation, and the solid sulfur obtained after the further separation also can enter the sulfur storage C6. The second gaseous substance obtained from the particulate purifier C2 is introduced into an amine liquid absorption tower C3 to obtain a hydrogen sulfide removal gas and a hydrogen sulfide containing liquid (amine liquid), respectively, and preferably the hydrogen sulfide removal gas is introduced into a carrier gas separator C5 to separate carrier gases that may be present therein, thereby obtaining a hydrogen-containing crude product containing a large amount of hydrogen. Preferably, the amine solution is introduced into a desorption tower C4 to desorb hydrogen sulfide gas (referred to as desorption hydrogen sulfide), and the desorbed hydrogen sulfide gas is recycled to the gas supply/distribution unit A1 through a pipeline.
The low-temperature plasma system for decomposing hydrogen sulfide provided by the invention has the following specific advantages:
(1) because the low-temperature plasma reactor is adopted to decompose the hydrogen sulfide, and the reactor uses a conductive solid material as a grounding electrode, compared with a liquid grounding electrode, the grounding electrode has larger micro-discharge current generated by discharge, and is more beneficial to the discharge decomposition reaction of hydrogen sulfide molecules, so the reactor can be used for the treatment process of the hydrogen sulfide with large flow and high concentration.
(2) Because the low-temperature plasma reactor is adopted to decompose the hydrogen sulfide, and the jacket structure is arranged on the outer side of the grounding electrode of the reactor, the temperature of the reactor 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 the hydrogen sulfide can smoothly flow out of a discharge area, the reactor is prevented from being blocked by the solidification of the sulfur, and the discharge is continuously and stably carried out.
(3) The decomposition of hydrogen sulfide is carried out by using a low-temperature plasma reactor which controls L1And L2The proportion relation is as follows: l is1：L21: (0.5-6000) (D1 is the distance between the outer side wall of the center electrode and the inner side wall of the grounding electrode, D1Is the thickness of the barrier medium, and L1＝d1-D1) (ii) a Preferably L1：L21: (2-3000), the structure of the reactor is matched, so that the conversion rate of the hydrogen sulfide can be obviously improved, and the decomposition energy consumption is reduced.
The present invention will be described in detail below by way of examples. In the following examples, various raw materials used were commercially available unless otherwise specified.
The thickness of the barrier dielectric is the same in the following examples and comparative examples.
The hydrogen sulfide conversion in the following examples was calculated according to the following formula:
percent conversion of hydrogen sulfide ═ moles of converted hydrogen sulfide/moles of initial hydrogen sulfide × 100%
The energy consumption for decomposing hydrogen sulfide in the following examples was measured by an oscilloscope and calculated using lissajous figures.
The volume of the inner cylinder of the reaction apparatus in example 1 below was 0.2L, and the volumes of the inner cylinders of the reaction apparatuses of the remaining examples and comparative examples can be calculated from the respective data.
Example 1
The hydrogen sulfide decomposition reaction was carried out using a low-temperature plasma system for decomposing hydrogen sulfide having the flow chart shown in fig. 3, and the low-temperature plasma reactor in this example had the structure shown in fig. 1.
The process flow of this example is as shown in the foregoing specific embodiment, and the structural parameters of the low-temperature plasma reactor are as follows:
the low temperature plasma reactor comprises:
the reactor comprises an inner cylinder, a reactor inlet, a gas product outlet and a liquid product outlet are respectively arranged on the inner cylinder, all cylinder structures of the inner cylinder are formed by blocking media, and the materials forming the blocking media are hard glass;
the outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively arranged on the outer cylinder;
the central electrode is arranged at the central axis position of the inner barrel, and the material forming the central electrode is a stainless steel metal rod;
the grounding electrode is wrapped on the outer side wall of the inner cylinder, the material for forming the grounding electrode is stainless steel metal foil, and the lower edge of the center electrode in the embodiment is lower than that of the grounding electrode;
l of the present embodiment1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：1600；
L1And thickness D of barrier medium1The ratio of (A) to (B) is 8: 1;
the position of the gas product outlet is arranged at a height H relative to the bottom of the inner cylinder1And the length L of the discharge region2The proportion relation between the components is as follows: h1：L2＝1：40；
The operation steps of the low-temperature plasma system for decomposing hydrogen sulfide are as follows:
nitrogen gas is introduced from a gas supply-distribution unit into a low-temperature plasma reactor of a plasma reaction unit, the nitrogen gas enters from a reactor inlet into an inner cylinder of the low-temperature plasma reactor to remove air in a discharge region, and gas is led out from a gas product outlet and a liquid product outlet. Meanwhile, a heat-conducting medium (specifically, dimethyl silicone oil) is introduced into the outer cylinder from the heat-conducting medium inlet, the introduced heat-conducting medium is led out from the heat-conducting medium outlet, and the temperature of the heat-conducting medium is kept at 145 ℃.
Then mixing the hydrogen sulfide gas and the Ar carrier gas sequentially through a gas distribution system and a mixer to obtainObtaining raw material gas H in the raw material gas2The volume fraction of S is 35%, the raw material gas enters the inner cylinder of the low-temperature plasma reactor from the inlet of the reactor, and the flow rate of the raw material gas is controlled so that the average residence time of the gas in a discharge region is 8.2S. And (3) after the raw material gas is introduced into the reactor for 30min, switching on an alternating-current high-voltage power supply, and adjusting the voltage and the frequency to form a plasma discharge field between the central electrode and the grounding electrode. Wherein the discharge conditions are as follows: the voltage was 18.0kV, the frequency was 3.8kHz, and the current was 0.94A. The hydrogen sulfide gas is ionized in the discharge area and decomposed into hydrogen and elemental sulfur, and the elemental sulfur generated by discharge slowly flows down along the inner cylinder wall and flows out from the liquid product outlet. The gas after reaction mainly flows out from the gas product outlet.
And the obtained gas product and the liquid product both enter a gas-liquid separator of a product separation unit for gas-liquid separation to respectively obtain a first gaseous substance and liquid sulfur, the first gaseous substance enters a particle purifier for further separation to obtain residual solid sulfur and a second gaseous substance, and the liquid sulfur and the residual solid sulfur both enter a sulfur storage. And further, the second gaseous substance enters an amine liquid absorption tower in the hydrogen sulfide circulation unit to respectively obtain hydrogen sulfide removing gas and hydrogen sulfide containing liquid, the hydrogen sulfide removing gas enters a gas carrier separator to separate carrier gas so as to obtain a hydrogen-containing crude product, the hydrogen sulfide containing liquid enters an analysis tower to analyze the hydrogen sulfide gas, and the hydrogen sulfide gas obtained by analysis is circulated back to the gas supply-distribution unit. The hydrogen-containing crude product is introduced into a solution containing sodium hydroxide for further purification to obtain hydrogen gas.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion was 76.5%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 13.5eV/H2S molecule (1 molecule of H per decomposition)2The energy required for S is 13.5 eV).
Comparative example 1
This comparative example used a low temperature plasma system for decomposing hydrogen sulfide similar to that of example 1, except that:
the ground electrode of the low-temperature plasma reactor in this comparative example was a liquid ground electrode, and LiCl and AlCl were in a molten state at a molar ratio of 1:13The liquid grounding electrode is also a heat-conducting medium, keeps the temperature at 145 ℃, and is placed in the outer cylinder of the reactor.
The flow rate of the mixed gas was controlled so that the mean residence time of the gas in the discharge zone was 18.5 s.
The rest is the same as in example 1.
As a result: h was measured after the hydrogen sulfide decomposition reaction of this comparative example was continued for 20min2S conversion rate is 14.9%, H after 1.5H of continuous discharge2The S conversion decreased to 5.1%.
The energy consumption for decomposition of this comparative example was 117eV/H2And (3) an S molecule.
Comparative example 2
This comparative example used a low temperature plasma system similar to comparative example 1 for hydrogen sulfide decomposition with the exception that:
l in the low temperature plasma reactor in this comparative example1：L2＝1：6500；
The flow rate of the mixed gas was controlled so that the mean residence time of the gas in the discharge zone was 18.5 s.
The rest is the same as in comparative example 1.
As a result: h was measured after the hydrogen sulfide decomposition reaction of this comparative example was continued for 20min2S conversion rate is 4.3%, H after 1.5H of continuous discharge2The S conversion decreased to 1.3%.
The energy consumption for decomposition of this comparative example was 134eV/H2And (3) an S molecule.
Example 2
The hydrogen sulfide decomposition reaction was carried out using a low-temperature plasma system for decomposing hydrogen sulfide having the flow chart shown in fig. 3, and the low-temperature plasma reactor in this example had the structure shown in fig. 2.
The process flow of this example is as shown in the foregoing specific embodiment, and the structural parameters of the low-temperature plasma reactor are as follows:
the low temperature plasma reactor comprises:
the inner cylinder is provided with a reactor inlet, a gas product outlet and a liquid product outlet respectively;
the outer cylinder is nested outside the inner cylinder, and a heat-conducting medium inlet and a heat-conducting medium outlet are respectively arranged on the outer cylinder;
the central electrode is arranged at the central axis position of the inner barrel, and the material forming the central electrode is a stainless steel metal rod;
the grounding electrode is arranged on the inner side wall of the inner cylinder, the material for forming the grounding electrode is stainless steel metal foil, and the lower edge of the center electrode is lower than that of the grounding electrode in the embodiment;
the blocking medium is arranged on the outer surface of the part of the central electrode extending into the inner cylinder, the upper edge of the blocking medium is higher than that of the grounding electrode, and the material forming the blocking medium is hard glass;
L1：L2＝1：2800；
L1and thickness D of barrier medium1The ratio of (A) to (B) is 10: 1;
H1and the length L of the discharge region2The proportion relation between the components is as follows: h1：L2＝1：350；
The operating procedure of the low temperature plasma system for decomposing hydrogen sulfide was the same as in example 1.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion was 73.1%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 13.7eV/H2And (3) an S molecule.
Comparative example 3
This comparative example used a low temperature plasma system similar to that of example 2 for hydrogen sulfide decomposition with the exception that:
comparison of booksThe grounding electrode of the low-temperature plasma reactor in the example was a liquid grounding electrode, and LiCl and AlCl were in a molten state at a molar ratio of 1:13The liquid grounding electrode is also a heat-conducting medium, keeps the temperature at 145 ℃, and is placed in the outer cylinder of the reactor.
The flow rate of the mixed gas was controlled so that the mean residence time of the gas in the discharge zone was 19.8 s.
The rest is the same as in example 2.
And this comparative example carried out the hydrogen sulfide decomposition reaction by the same operation method as that of example 2.
As a result: h was measured after the hydrogen sulfide decomposition reaction of this comparative example was continued for 20min2S conversion rate is 15.6%, H after 1.5H of continuous discharge2The S conversion decreased to 5.7%.
The energy consumption for decomposition of this comparative example was 115eV/H2And (3) an S molecule.
Comparative example 4
This comparative example used a low temperature plasma apparatus for decomposing hydrogen sulfide similar to that of comparative example 3, except that:
l in the low temperature plasma reactor in this comparative example1：L2＝1：6500；
The flow rate of the mixed gas was controlled so that the mean residence time of the gas in the discharge zone was 19.8 s.
The rest is the same as in comparative example 3.
As a result: h was measured after the hydrogen sulfide decomposition reaction of this comparative example was continued for 20min2S conversion rate is 4.5%, H after 1.5H of continuous discharge2The S conversion decreased to 1.4%.
The energy consumption for decomposition of this comparative example was 132eV/H2And (3) an S molecule.
Example 3
This example uses a low temperature plasma system for decomposing hydrogen sulfide similar to that of example 1, except that in this example:
all side walls of the inner cylinder are formed by grounding electrodes, and the grounding electrodes are made of stainless steel metal foils;
the blocking medium is arranged on the inner side wall of the inner barrel in a surrounding mode;
L1：L2＝1：200；
L1and thickness D of barrier medium1The ratio of (A) to (B) is 18: 1;
H1and the length L of the discharge region2The proportion relation between the components is as follows: h1：L2＝1：130；
In this example, H was introduced into the inner cylinder of the plasma reactor from the inlet of the reactor2S/Ar mixed gas, in which H2The volume fraction of S was 35%, and the flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge zone was 10.2S. H2And (3) introducing the S/Ar mixed gas into the reactor for 30min, switching on an alternating-current high-voltage power supply, and adjusting the voltage and the frequency to form a plasma discharge field between the central electrode and the grounding electrode. Wherein the discharge conditions are as follows: the voltage was 21.3kV, the frequency was 7.0kHz, and the current was 1.01A.
The rest is the same as in example 1.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion was 77.2%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 14.1eV/H2And (3) an S molecule.
Example 4
This example uses a low temperature plasma system for decomposing hydrogen sulfide similar to that of example 1, except that:
all side walls of the inner cylinder are formed by grounding electrodes, and the grounding electrodes are made of copper foils;
the blocking medium is arranged on the inner side wall of the inner barrel in a surrounding mode;
L1：L2＝1：1000；
L1and thickness D of barrier medium1The ratio of (A) to (B) is 0.5: 1;
H1and the length L of the discharge region2The proportion relation between the components is as follows: h1：L2＝1：150；
In this example, H was introduced into the inner cylinder of the plasma reactor from the inlet of the reactor2S/Ar mixed gas, in which H2The volume fraction of S was 35%, and the flow rate of the mixed gas was controlled so that the average residence time of the gas in the discharge zone was 9.6S. H2And (3) introducing the S/Ar mixed gas into the reactor for 30min, switching on an alternating-current high-voltage power supply, and adjusting the voltage and the frequency to form a plasma discharge field between the central electrode and the grounding electrode. Wherein the discharge conditions are as follows: the voltage was 14.7kV, the frequency was 1.3kHz, and the current was 1.17A.
The rest is the same as in example 1.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion was 76.8%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 14.5eV/H2And (3) an S molecule.
Example 5
This example uses a low temperature plasma system for decomposing hydrogen sulfide similar to that of example 1, except that in this example:
L1and thickness D of barrier medium1The ratio of (A) to (B) is 35: 1.
the rest is the same as in example 1.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion was 72.7%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 23.5eV/H2And (3) an S molecule.
Example 6
This example uses a low temperature plasma system for decomposing hydrogen sulfide similar to that of example 2, except that:
L1and length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：3500。
The rest is the same as in example 2.
And this example carried out the hydrogen sulfide decomposition reaction in the same manner as in example 2.
As a result: in this example, H was measured after the hydrogen sulfide decomposition reaction was continued for 20min2The S conversion rate was 71.6%; and the discharge state and H are not abnormal after the discharge lasts for 100H2The S conversion rate is kept stable. And the decomposition energy consumption of the embodiment is 24.5eV/H2And (3) an S molecule.
From the above results, it can be seen that when the low-temperature plasma device for decomposing hydrogen sulfide provided by the present invention is used to decompose hydrogen sulfide, the conversion rate of hydrogen sulfide can be significantly improved compared with the prior art, and the low-temperature plasma device for decomposing hydrogen sulfide provided by the present invention can maintain a high conversion rate of hydrogen sulfide for a long period of time with low energy consumption for decomposition.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (22)

1. A low-temperature plasma system for decomposing hydrogen sulfide comprises a gas supply-distribution unit, a plasma reaction unit and a product separation unit which are sequentially connected through pipelines, wherein the plasma reaction unit comprises a low-temperature plasma reactor and a plasma power supply, and the reactor comprises:
the reactor comprises an inner cylinder (1), wherein a reactor inlet (11) and a product outlet are respectively arranged on the inner cylinder (1);
the outer cylinder (2) is nested outside the inner cylinder (1), and a heat-conducting medium inlet (21) and a heat-conducting medium outlet (22) are respectively arranged on the outer cylinder (2);
a center electrode (3), the center electrode (3) being disposed in the inner barrel (1);
the barrier medium (6) is arranged on the inner side wall of the inner barrel (1) in a surrounding mode or is arranged on the outer surface of the central electrode (3) in a wrapping mode, or the barrier medium (6) forms at least part of the side wall of the inner barrel (1) so that at least part of the barrier medium (6) surrounds the central electrode (3);
the grounding electrode (4) is made of a solid conductive material, the grounding electrode (4) is arranged on the outer side wall of the inner cylinder (1) in a surrounding mode, or the grounding electrode (4) forms at least part of the side wall of the inner cylinder (1), and the blocking medium is arranged at a position enabling a discharge area between the central electrode (3) and the grounding electrode (4) to be separated by the blocking medium;
wherein the distance between the outer side wall of the center electrode (3) and the inner side wall of the ground electrode (4) is D1, and the thickness of the blocking medium (6) is D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
2. The hydrogen sulfide decomposing low temperature plasma system of claim 1 wherein in the low temperature plasma reactor, L1：L2＝1：(2～3000)。
3. The hydrogen sulfide decomposing low temperature plasma system of claim 1 wherein in the low temperature plasma reactor, L1With the thickness D of the barrier medium (6)1The proportion relation is as follows: l is1：D1＝(0.05～100)：1。
4. The hydrogen sulfide decomposing low temperature plasma system of claim 1 wherein in the low temperature plasma reactor, L1With the thickness D of the barrier medium (6)1The proportion relation is as follows: l is1：D1＝(0.1～30)：1。
5. The hydrogen sulfide decomposing low temperature plasma system according to any one of claims 1 to 4, wherein in the low temperature plasma reactor, the blocking medium (6) forms at least part of the side wall of the inner barrel (1) such that at least part of the blocking medium (6) surrounds the central electrode (3); and the grounding electrode (4) is arranged on the outer side wall of the inner cylinder (1) in a surrounding manner.
6. The hydrogen sulfide decomposing low temperature plasma system according to any one of claims 1 to 4, wherein in the low temperature plasma reactor the barrier medium (6) forms the entire side wall of the inner barrel (1).
7. A low-temperature plasma system for decomposing hydrogen sulfide comprises a gas supply-distribution unit, a plasma reaction unit and a product separation unit which are sequentially connected through pipelines, wherein the plasma reaction unit comprises a low-temperature plasma reactor and a plasma power supply, and the reactor comprises:
the reactor comprises an inner cylinder (1), wherein a reactor inlet (11) and a product outlet are respectively arranged on the inner cylinder (1);
the outer cylinder (2) is nested outside the inner cylinder (1), and a heat-conducting medium inlet (21) and a heat-conducting medium outlet (22) are respectively arranged on the outer cylinder (2);
a center electrode (3), the center electrode (3) being disposed in the inner barrel (1);
the barrier medium (6), the barrier medium (6) is wrapped and arranged on the outer surface of the central electrode (3);
the grounding electrode (4) is made of a solid conductive material, and the grounding electrode (4) is arranged on the inner side wall of the inner barrel (1) in a surrounding mode;
wherein the distance between the outer side wall of the center electrode (3) and the inner side wall of the ground electrode (4) is D1, and the thickness of the blocking medium (6) is D1And L is1＝d1-D1，L1And length L of discharge region2The proportion relation between the components is as follows: l is1：L2＝1：(0.5～6000)。
8. The hydrogen sulfide decomposing low temperature plasma system of claim 1, wherein in the low temperature plasma reactor, the material forming the blocking medium is an electrically insulating material.
9. The hydrogen sulfide decomposing low temperature plasma system of claim 1, wherein in the low temperature plasma reactor, the material forming the barrier medium is selected from at least one of glass, ceramic, enamel, polytetrafluoroethylene, and mica.
10. The hydrogen sulfide decomposing low temperature plasma system according to claim 1, further comprising a ground wire (5) provided on an outer side wall of the outer cylindrical housing (2) and having one end electrically connected to the ground electrode (4).
11. The hydrogen sulfide decomposing low temperature plasma system according to claim 1, wherein in the low temperature plasma reactor, the reactor inlet (11) is provided at an upper portion of the inner tube (1), and the product outlet is provided at a lower portion and/or a bottom portion of the inner tube (1).
12. The hydrogen sulfide decomposing low temperature plasma system according to claim 11, wherein in the low temperature plasma reactor, the product outlets include a gaseous product outlet (12) and a liquid product outlet (13), and the reactor inlet (11) is disposed at an upper portion of the inner tube (1), the gaseous product outlet (12) is disposed at a lower portion of the inner tube (1), and the liquid product outlet (13) is disposed at a bottom portion of the inner tube (1).
13. The hydrogen sulfide decomposing low temperature plasma system according to claim 12, wherein in the low temperature plasma reactor, the gas product outlet (12) is provided below the discharge region, and the gas product outlet (12) is providedThe position of the inner cylinder (1) is relative to the height H of the bottom of the inner cylinder1And the length L of the discharge region2The proportion relation between the components is as follows: h1：L2＝1：(0.05～25000)。
14. The hydrogen sulfide decomposing low temperature plasma system according to claim 12, wherein in the low temperature plasma reactor, the gaseous product outlet (12) is disposed below the discharge region, and the position of disposing the gaseous product outlet (12) is at a height H with respect to the bottom of the inner tube (1)1And the length L of the discharge region2Has a proportional relation of H1：L2＝1：(0.1～10000)。
15. The hydrogen sulfide decomposing low temperature plasma system according to claim 12, wherein in the low temperature plasma reactor, the gaseous product outlet (12) is disposed below the discharge region, and the position of disposing the gaseous product outlet (12) is at a height H with respect to the bottom of the inner tube (1)1And the length L of the discharge region2Has a proportional relation of H1：L2＝1：(0.5～1000)。
16. The hydrogen sulfide decomposing low temperature plasma system according to claim 1, wherein the heat transfer medium inlet (21) and the heat transfer medium outlet (22) are provided at a lower portion and an upper portion of the outer cylindrical housing (2), respectively, in the low temperature plasma reactor.
17. The hydrogen sulfide decomposing low temperature plasma system according to claim 1, wherein in the low temperature plasma reactor, the material forming the ground electrode (4) is selected from a graphite tube, a metal foil or a metal mesh.
18. The hydrogen sulfide decomposing low temperature plasma system according to claim 1, wherein in the low temperature plasma reactor, the material forming the center electrode (3) is selected from at least one of a graphite tube, a metal rod, a metal tube and a graphite rod.
19. The system for decomposing hydrogen sulfide of claim 1, further comprising a hydrogen sulfide recycling unit for recovering hydrogen sulfide from the gas phase substance containing hydrogen sulfide obtained in the product separation unit and recycling the resulting hydrogen sulfide to the gas supply-distribution unit or the plasma reaction unit.
20. The system for decomposing hydrogen sulfide according to claim 1, further comprising a hydrogen sulfide circulation unit, wherein the hydrogen sulfide circulation unit comprises an amine liquid absorption tower for absorbing hydrogen sulfide and a desorption tower for desorbing hydrogen sulfide.
21. The hydrogen sulfide decomposing cryogenic plasma system of claim 1 wherein the product separation unit contains a gas-liquid separator and optionally a particulate purifier and/or a gas-laden separator.
22. A method of decomposing hydrogen sulfide, the method being carried out in the low temperature plasma system of decomposing hydrogen sulfide of any one of claims 1 to 21, the method comprising:
raw material gas containing hydrogen sulfide from the gas supply-distribution unit enters the plasma reaction unit through a pipeline;
in the presence of a plasma discharge field generated by a low-temperature plasma reactor and a plasma power supply in the plasma reaction unit, the feed gas enters an inner cylinder of the low-temperature plasma reactor through an inlet of the reactor to carry out hydrogen sulfide decomposition reaction, and a gas-phase substance and a liquid-phase elemental sulfur obtained after the reaction are led out of the low-temperature plasma reactor through a product outlet;
gas-phase substances and liquid-phase elemental sulfur from the low-temperature plasma reactor enter a product separation unit to be separated so as to respectively obtain elemental sulfur, hydrogen and tail gas containing hydrogen sulfide;
optionally introducing the hydrogen sulfide-containing tail gas obtained in the product separation unit into a hydrogen sulfide recycling unit for separation to obtain hydrogen sulfide recycled to the gas supply-distribution unit or the plasma reaction unit.
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