Acetylene preparation method and arc plasma reaction device

Abstract

Provided in the present application are an acetylene preparation method and an arc plasma reaction device. The preparation method comprises: feeding a gas carrying a carbon powder into an arc plasma torch of a plasma reactor, and subjecting same to arc heating to gasify the carbon powder, so as to form a carbon steam jet flow; and inputting a reaction gas into the plasma reactor, so as to mix the reaction gas and the carbon steam jet flow and perform a cracking reaction to obtain acetylene, wherein the reaction gas comprises hydrogen or a mixture of hydrogen and a hydrocarbon-containing compound.

Description

Acetylene preparation method and arc plasma reaction device

[0001] Related applications

[0002] This application claims priority to Chinese patent application No. 202311694031.7 filed on December 8, 2023, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application relates to the technical field of acetylene production technology, and in particular to an acetylene preparation method and an arc plasma reaction device. Background Art

[0004] Acetylene is one of the basic chemical raw materials produced by converting carbonaceous materials. Traditional methods for producing industrial acetylene mainly include the calcium carbide method, but this method is energy-intensive and causes significant pollution.

[0005] Compared to the calcium carbide method for producing acetylene, arc plasma pyrolysis of pulverized coal to directly produce acetylene theoretically offers advantages such as resource conservation, reduced pollution emissions, and low energy consumption. It is considered a revolution in the production of acetylene by the calcium carbide method. Since the 1920s, GB286825 has disclosed the production of acetylene by arc heating gasification / pyrolysis of carbonaceous materials (including pulverized coal, coke, etc.) in a gas-phase reaction dominated by CH . Despite continuous research for over 90 years, this technology has yet to achieve industrial application. Major challenges lie in the high power consumption, easy coking, and scale-up of large-scale industrial reactors for acetylene production from pulverized coal. These issues result in high operating costs and instability, and the economic efficiency (primarily in terms of reactor energy consumption) falls far short of ideal values. Summary of the Invention

[0006] The main purpose of this application is to propose a method for preparing acetylene and an arc plasma reaction device, which can quickly and evenly mix arc plasma with coal powder and improve the temperature uniformity of the reaction zone, thereby improving product uniformity and energy efficiency. It also has multiple advantages such as high power, high energy efficiency, and avoidance of coking on the reactor wall, thus taking into account various needs of industrial applications.

[0007] To achieve the above objectives, on the one hand, the present application proposes a method for preparing acetylene, comprising the following steps:

[0008] S1, feeding gas carrying carbon powder into an arc plasma torch of a plasma reactor, and heating the carbon powder with the arc to gasify the carbon powder to form a carbon vapor jet;

[0009] S2, inputting a reaction gas into the plasma reactor so that the reaction gas and the carbon vapor jet are mixed and cracked to obtain acetylene, wherein the reaction gas includes hydrogen or a mixture of hydrogen and a hydrocarbon compound.

[0010] In one embodiment, in step S1 , the average enthalpy of the carbon steam jet is 30-80 MJ / kg.

[0011] In one embodiment, in step S1 , the ratio N of the mass flow rate of the carbon powder to the mass flow rate of the gas input into the plasma torch is greater than 1.

[0012] In one embodiment, in step S1 , the ratio N of the mass flow rate of the carbon powder to the mass flow rate of the gas input into the plasma torch is greater than 5.

[0013] In one embodiment, the ratio of the momentum of the reaction gas component perpendicular to the flow direction of the carbon vapor jet to the momentum of the carbon vapor jet is M, M=0.2-5; and / or, M=0.5-2.

[0014] In one embodiment, the hydrocarbon-containing compound in step S2 includes at least one of hydrocarbon-containing gas, hydrocarbon-containing liquid, and hydrocarbon-containing solid powder, and / or the hydrocarbon-containing solid powder includes coal powder, waste plastic powder or waste resin powder, and the volatile matter of the coal powder is greater than 20%.

[0015] In one embodiment, the step S2 further comprises inputting an oxidant; the oxidant comprises gaseous or liquid H2O, CO2, O2; and / or,

[0016] In step S1, the carbon powder includes coal powder, coal-based coke powder, blue carbon powder, petroleum coke powder, waste resin powder, waste plastic powder or carbon powder discharged from a plasma reactor; and / or,

[0017] The mass content of hydrogen in the carbon powder is not greater than 1.5%; and / or,

[0018] The gas includes one or more of oxygen, carbon monoxide, carbon dioxide, argon, nitrogen, and air; and / or,

[0019] The hydrogen-to-carbon molar ratio (H / C) of the total gas phase in the plasma reactor is 3-8.

[0020] On the other hand, the present application provides an arc plasma reaction device, comprising:

[0021] A reactor having a reaction chamber formed therein with openings at both ends, wherein a plurality of medium delivery nozzles are provided on the side walls of the reaction chamber for inputting reaction gas; and

[0022] A plasma torch, comprising a first electrode accommodating chamber, a first solid powder nozzle, and an arc channel, wherein the arc channel is coaxially arranged with the reaction chamber, one end of the arc channel is in communication with the first electrode accommodating chamber and the first solid powder nozzle, and the other end of the arc channel is in communication with an opening at one end of the reaction chamber, a first arc electrode is disposed in the first electrode accommodating chamber, and the first solid powder nozzle is used to deliver carbon powder into the arc channel;

[0023] Wherein, a plurality of electrode holes are provided on the side wall of the reaction chamber, and a second arc electrode with a polarity opposite to that of the first arc electrode is provided in each of the electrode holes.

[0024] In one embodiment, the plurality of medium delivery nozzles are evenly arranged along the circumferential direction of the reaction chamber, and the axes of the plurality of medium delivery nozzles intersect a circle within the cross section of the reactor and coaxial with the reaction chamber, and the diameter of the circle is less than 1 / 3 of the diameter of the reaction chamber; and / or,

[0025] The multiple electrode holes are spaced apart along the circumferential direction of the reaction chamber, and the angle α between the axis of each of the multiple electrode holes and the central axis of the reaction chamber is 30° to 150°. The axes of the multiple electrode holes intersect a circle coaxial with the reaction chamber in the cross section of the reactor, and the diameter of the circle is less than 1 / 3 of the diameter of the reaction chamber.

[0026] In one embodiment, the plurality of medium delivery nozzles coincide with the plurality of electrode holes in the reaction chamber.

[0027] In one embodiment, the first electrode accommodating chamber is provided with one, and the first electrode accommodating chamber is coaxially arranged with the reactor; at the same time, there are multiple solid powder nozzles, which are evenly distributed around the axis of the arc channel, and the angle β between the axis of the solid powder nozzle and the axis of the first electrode is 10° to 90°; or,

[0028] There are multiple first electrode accommodating cavities, and the polarities of the multiple first arc electrodes are the same. The multiple first electrode accommodating cavities are evenly distributed circumferentially around the axis of the arc channel, and the angle γ between the axes of the multiple first arc electrodes and the axis of the arc channel is 10° to 90°; at the same time, there is one first solid powder nozzle, and the axis of the first solid powder nozzle is coaxially arranged with the arc channel.

[0029] In one embodiment, a plurality of second solid powder nozzles are arranged on the side wall of the reaction chamber (201) or around the plasma torch, and the plurality of second solid powder nozzles are evenly arranged along the circumferential direction of the reaction chamber or the plasma torch, or the axial positions of the plurality of second solid powder nozzles are located between the first solid powder nozzle and below the second arc electrode or below the second arc electrode.

[0030] The inner wall of the arc channel is made of a high-resistance material; the inner wall of the reaction chamber is made of a porous material.

[0031] In the technical solution provided by the present application, carbon powder is gasified in a plasma torch to form a high-enthalpy, high-flow carbon steam jet. The high-temperature carbon steam jet is quickly mixed with the reaction gas, which can increase the mixing speed and mixing uniformity of the two, improve the heating uniformity, thereby increasing the acetylene yield and significantly reducing the energy consumption of acetylene generation; rapid mixing increases the mixing speed and shortens the reaction time, thereby increasing the reactor space velocity and reducing the reactor energy consumption; the carbon powder on the periphery of the arc plasma channel isolates the radiation and convection heat transfer of the plasma channel to the arc channel wall, reducing the heat loss of the arc plasma torch; in addition, the generation of acetylene using carbon powder as the carbon source has the lowest acetylene generation enthalpy, further reducing the energy consumption of acetylene generation and avoiding coking of the arc channel wall. A small amount of oxidizing medium is introduced into the reaction chamber wall to eliminate the problem of coking of the reactor wall. Compared with the calcium carbide method, it consumes less energy and causes less pollution.

[0032] Furthermore, the present invention enables the one-step conversion of solid carbon feedstock into acetylene using arc plasma, with low energy consumption, while also maintaining low energy consumption during the carbon powder gasification process. This invention addresses the existing issues of difficult gas-solid mixing and low acetylene yields caused by the high dispersion of the pyrolysis process during arc pyrolysis of pulverized coal to produce acetylene. This invention also reduces reactor coking during arc conversion of solid carbon feedstock into acetylene. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0034] FIG1 is a schematic flow diagram of an embodiment of a method for preparing acetylene provided in the present application;

[0035] FIG2 is a schematic structural diagram of an arc plasma reaction device according to an embodiment of the present application;

[0036] FIG3 is a schematic structural diagram of another embodiment of the arc plasma reaction device provided by the present application;

[0037] FIG4 is a schematic structural diagram of another embodiment of the arc plasma reaction device provided by the present application;

[0038] FIG5 is a cross-sectional view of the AA section (second arc electrode) of FIG2, 3, and 4;

[0039] FIG6 is a cross-sectional view taken along line BB of FIG3 ;

[0040] FIG7 is a cross-sectional view taken along line CC of FIG4 ;

[0041] FIG8 is a schematic diagram of the reaction principle of the arc plasma reaction device provided in this application.

[0042] Description of Figure Numbers:

[0043] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0045] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0046] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0047] Acetylene is one of the basic chemical raw materials produced by converting carbonaceous materials. Traditional methods for producing industrial acetylene mainly include the calcium carbide method, but this method is energy-intensive and causes significant pollution.

[0048] Compared to the calcium carbide method for producing acetylene, arc plasma pyrolysis of pulverized coal to directly produce acetylene theoretically offers advantages such as resource conservation, reduced pollution emissions, and low energy consumption, and is considered a revolution in the production of acetylene by the calcium carbide method. Since the 1920s, when GB286825 published by Igfarben Industrie et al. proposed the production of acetylene from carbonaceous materials (including pulverized coal and coke) by arc heating through gasification / pyrolysis in a gas-phase reaction dominated by CH , this technology has been continuously researched for over 90 years. However, this technology has yet to achieve industrial application. Major challenges include high power consumption, easy coking, and scale-up issues in large-scale industrial reactors for pyrolysis of pulverized coal. This leads to high operating costs and instability, and the economic performance (primarily in terms of reactor energy consumption) falls far short of ideal values.

[0049] The main reason for the above problems is that the reactor device used for industrial production of acetylene by arc heating pulverized coal must simultaneously meet the following requirements: (1) stable, long-lasting, and sufficiently high arc power; (2) sufficiently high power utilization efficiency; and (3) avoidance of reactor and electrode coking. These requirements involve numerous interrelated factors and are difficult to meet simultaneously.

[0050] For example, high-temperature arc plasma heats pulverized coal quickly, reaching chemical equilibrium quickly and reacting rapidly. After coal pyrolysis and gasification, acetylene is rapidly generated in the temperature range of 1600-3500 K. However, this process must be maintained for an extremely short time, less than 3 milliseconds. Otherwise, the carbon atoms in the CH gas system will rapidly polymerize and deposit as carbon black, an irreversible reaction. Longer maintenance times can reduce acetylene yields. Furthermore, due to the highly concentrated plasma energy and small volume, relying solely on gas heat transfer to achieve a rapid and uniform temperature increase in the pulverized coal zone is difficult. Consequently, pulverized coal that does not enter the high-temperature zone cannot be gasified or cannot be fully gasified. Volatile components released by the pulverized coal in the low-temperature zone are easily converted into tar and methane, preventing acetylene from being produced. Furthermore, the low concentration of pulverized coal in the high-temperature zone increases the energy consumption for acetylene production, resulting in high pulverized coal consumption and high acetylene production energy consumption. Therefore, the pulverized coal and plasma or high-temperature gas must be mixed uniformly within an extremely short time. This requires addressing the large-scale, rapid, and uniform mixing of the high-speed plasma jet and the low-speed pulverized coal gas-solid two-phase flow.

[0051] For example, plasma torches are beneficial for increasing heating power, stabilizing the arc, extending electrode life due to the low current, and preventing electrode coking. However, the plasma torch itself consumes more than 10% of energy. Moreover, to improve the thermal efficiency of the plasma torch and stabilize the arc, a large amount of working gas is required, which almost takes up most of the gas in the atmosphere required for the reaction. Pulverized coal can only be transported in a small amount of gas, making it difficult for the pulverized coal to mix with the plasma jet. However, directly using arc heating in the reactor without a plasma torch has problems such as pulverized coal coking on the electrodes. The arc voltage is difficult to increase, making it difficult for the arc power to meet industrial-scale requirements. Relying on increasing the arc current to increase the heating power leads to increased electrode loss. Moreover, due to the self-contraction characteristics of the arc, increasing the current does not increase the plasma volume proportionally, which makes it difficult for the pulverized coal to mix with the plasma and heat it evenly, resulting in reduced reactor energy efficiency.

[0052] Table 1 lists the calculated enthalpy of acetylene formation and energy consumption under actual reaction conditions for solid carbon, methane, and propane as raw materials, calculated under the assumption that the carbon conversion rate and acetylene yield are 1. Theoretically, the enthalpy of acetylene formation and actual reaction energy consumption for acetylene production using solid carbon as a raw material are lower than those using hydrocarbon raw materials, with methane having the highest energy consumption, followed by propane. Theoretical analysis shows that the energy consumption of acetylene production from pulverized coal pyrolysis is between that of methane (natural gas) and propane. However, currently reported industrial production data and experimental data show the opposite, with energy consumption for acetylene production from pulverized coal pyrolysis being much higher than that from natural gas.

[0053] In theory, producing acetylene by gasifying carbon powder can achieve the highest energy efficiency and avoid gas-solid mixing issues. However, due to the low dissociation temperature of hydrogen (~3500K) and high thermal conductivity, hydrogen plasma torches struggle to generate plasma with an average temperature higher than the carbon powder gasification temperature (>4200K). Therefore, existing hydrogen plasma torch technology struggles to achieve direct carbon powder gasification.

[0054] Table 1 Acetylene formation enthalpy and energy consumption (C (s) 、H2 formation enthalpy is 0)

[0055] In view of this, an embodiment of the present application provides a method for preparing acetylene with low energy consumption and low pollution. Referring to Figures 1 to 8, the method for preparing acetylene includes the following steps:

[0056] S1, feeding gas carrying carbon powder into an arc plasma torch of a plasma reactor, and heating the carbon powder with the arc to gasify the carbon powder to form a carbon vapor jet.

[0057] In this embodiment, gas is used to transport carbon powder. The gas (i.e., the gas carrying the carbon powder) is a non-halogen, hydrogen-free gas, preferably a low-cost gas to reduce costs. The gas is a diatomic molecule with a dissociation temperature no lower than the sublimation temperature of the carbon powder (i.e., no less than 4200K), or a gas that reacts strongly with carbon below the sublimation temperature of the carbon powder, or a gas with low thermal conductivity formed below the sublimation temperature of the carbon powder. This allows the gas to release a large amount of heat due to recombination during arc heating, or to form a high temperature field around the arc due to the formation of a low-thermal-conductivity gas, thereby facilitating the gasification of the carbon powder to form a carbon plasma and increase the plasma enthalpy. The gas includes any one of carbon monoxide, argon, nitrogen, carbon dioxide, water vapor, oxygen, and air, or a mixture of any two or any n (n>2) of these gases. Carbon dioxide or water vapor can also be used to transport coal powder, which offers improved safety, but this will result in energy loss due to the reaction with carbon to produce coal gas.

[0058] In this embodiment, the mass content of hydrogen in the carbon powder is no more than 1.5%. By selecting carbon powder with a low hydrogen content as a raw material, the difficulty of carbon powder gasification can be reduced and the efficiency of carbon powder gasification can be improved. The carbon powder includes carbon black, anthracite powder, coal-based coke powder, blue carbon (semi-coke) powder, petroleum coke powder or reacted coal coke powder, etc. When using anthracite, the anthracite powder and waste resin powder can also be pre-processed, including removing ash (mechanical method, acid-base method), drying (>150°C), and high-temperature pyrolysis dehydrogenation (>500°C); other carbon powders can also be treated similarly. The carbon powder is dried before use to reduce the energy loss caused by the water gas reaction. Compared with the technology using chain hydrocarbons (such as natural gas, propane, etc.) as the carbon source, the generation of acetylene using carbon powder as the carbon source has the lowest acetylene formation enthalpy, thereby reducing the energy consumption of acetylene generation.

[0059] In addition, to improve the gasification efficiency of carbon powder, in this embodiment, the particle size of the carbon powder is less than 100 μm; the smaller the particle size of carbon powder, the larger the specific surface area of ​​carbon powder, and it is easier to be heated and gasified, but carbon powder with too small particles is difficult to enter the arc.

[0060] In the gas-carrying carbon powder, the molar ratio of the carbon powder to the non-carbon elements in the gas is greater than 2, and preferably greater than 5. Since the gas is not essential for the reaction in step S2, it removes some energy, resulting in energy loss. It also reduces the residence time of the carbon powder in the plasma, hindering its gasification. However, too little gas can also hinder carbon powder transport. Therefore, in this embodiment, the ratio N of the mass flow rate of the carbon powder to the mass flow rate of the gas input to the plasma torch is preferably greater than 1, preferably greater than 5, to minimize energy loss while ensuring carbon powder transport.

[0061] In the carbon vapor jet, the gasification rate of the carbon powder is 20% to 70%. In this way, on the one hand, sufficient carbon powder utilization can be ensured, and on the other hand, the remaining ungasified carbon powder is enriched near the inner wall surface of the plasma torch 10, which can isolate the plasma from transferring heat to the inner wall surface of the plasma torch 10, thereby reducing the energy consumption of acetylene generation, and at the same time protecting and flushing the inner wall surface of the plasma torch 10 and the inner wall surface of the reaction chamber 201 connected to the plasma torch 10, thereby preventing wall coking; in addition, the carbon powder gasification temperature is 4 , above 200K, the carbon plasma temperature can reach above 6,000K, the gas phase carbon jet (plasma) temperature is 4,500~10,000K, and the specific enthalpy of the generated carbon vapor jet is 30~80MJ / kg-C (excluding solid phase carbon), which is helpful for subsequent cracking reactions; the speed of the carbon vapor jet is greater than 100m / s, and the average enthalpy of the carbon vapor jet is 30~80MJ / kg, that is, the average enthalpy of each kilogram of carbon vapor jet is 30~80MJ.

[0062] S2: A reaction gas is introduced into the plasma reactor, where it mixes with the carbon vapor jet and undergoes a cracking reaction to produce acetylene. The reaction gas comprises hydrogen or a mixture of hydrogen and a hydrocarbon compound. The hydrocarbon compound is added to supplement the carbon source to fully utilize the energy of the carbon plasma and increase acetylene production.

[0063] In this embodiment, hydrogen and a supplementary carbon source (containing hydrocarbons) can be input radially and tangentially, so that the hydrogen, the supplementary carbon source, and the carbon vapor jet collide and mix at nearly right angles, and generate a rotating flow in the reaction chamber; in actual application, rapid cooling can be used to control the mixing reaction time Δt to obtain acetylene; when the supplementary carbon source (containing hydrocarbons) is a gas, the mixing reaction time Δt is 1.5 to 3 ms; when the supplementary carbon source (containing hydrocarbons) is a solid powder, the mixing reaction time Δt is 2.5 to 5 ms. Since the specific enthalpy of carbon plasma is high and the energy it carries is large, a certain amount of carbon source needs to be supplemented to fully utilize the energy carried by the carbon plasma. The ratio of the molar flow rate of carbon that can volatilize CH small molecules from hydrocarbon-containing compounds to the molar flow rate of carbon in the carbon plasma is 0 to 3; the hydrocarbon-containing compound includes at least one of a hydrocarbon-containing gas, a hydrocarbon-containing liquid, and a hydrocarbon-containing solid powder. For example, hydrocarbon compounds include but are not limited to natural gas, coke oven gas, coalbed methane, ethane, propane, ethylene, propyne, butyne, butane, and light oil; including chain hydrocarbons (non-acetylene, including methane, ethylene, propyne, butyne, etc.) separated from the cracking reaction products of the reactor; hydrocarbon-containing solid powders include coal powder, waste resin powder, waste plastic powder or carbon powder discharged from a plasma reactor, and the coal powder is highly volatile coal powder such as bituminous coal, long flame coal, etc., with a volatile matter content greater than 20%; the coal powder can be dried before use to increase the acetylene yield.

[0064] The hydrocarbon-containing compounds do not include aromatic hydrocarbons containing benzene rings. The carbon rings of aromatic hydrocarbons containing benzene rings are not easily broken to form small hydrocarbon molecules, making them unsuitable for acetylene production. The waste resin powder and waste plastic powder containing hydrocarbon compounds should also not contain excessive impurities other than hydrocarbon compounds. Organic impurities increase energy consumption, while inorganic impurities easily form scars on the reactor walls.

[0065] Hydrogen is essential for acetylene production, and adding excess hydrogen to reactor 20 helps maintain acetylene stability and thus maintain acetylene production. Excessive hydrogen increases energy consumption. In this embodiment, the hydrogen-to-carbon molar ratio (H / C) of the total gas phase in the plasma reactor is 3 to 8. Specifically, after the carbon vapor jet, hydrogen, and reactant gas are mixed, the elemental molar ratio of hydrogen to carbon (H / C) is 3 to 8; or, in the mixture of carbon plasma, hydrogen, and the gaseous products of the pyrolysis of hydrocarbon-containing solid powder, the elemental molar ratio of hydrogen to carbon (H / C) is 3 to 8.

[0066] The cracking reaction in this application primarily produces acetylene, hydrogen, carbon monoxide, and a small amount of chain hydrocarbons. After the cracking reaction, the reaction products can be separated, with the separated acetylene collected as the product. The remaining chain hydrocarbon gas and some hydrogen can be recycled to reactor 20 to continue the cracking reaction as supplemental carbon and hydrogen sources. The average thermodynamic equilibrium temperature of the hydrocarbon mixture before acetylene conversion is 1,600 to 2,200 K.

[0067] Taking the pyrolysis of pulverized coal to produce acetylene as an example, the high-temperature arc plasma heats the pulverized coal rapidly, achieving chemical equilibrium quickly and generating a rapid reaction rate. After pyrolysis and gasification, acetylene is rapidly generated in the 1,600-3,500 K temperature range. However, if this temperature is maintained for too long, carbon atoms in the hydrocarbon mixture will continuously aggregate and precipitate into carbon black, resulting in a decrease in acetylene yield. Furthermore, due to the highly concentrated plasma energy and small volume, relying solely on gas heat transfer to achieve a rapid and uniform temperature increase in the pulverized coal zone is difficult. Consequently, pulverized coal that has not yet entered the high-temperature zone will not be fully or completely gasified, resulting in a low acetylene yield. Furthermore, the volatile components released by the pulverized coal in the low-temperature zone are easily converted into tar and methane, preventing acetylene from being produced. Furthermore, the low pulverized coal concentration in the high-temperature zone increases the energy consumption for acetylene production, resulting in high pulverized coal consumption, high energy consumption for acetylene production, and low acetylene yield.

[0068] In view of this, in this embodiment, hydrogen and a gaseous supplementary carbon source mixture (containing hydrocarbon gas or hydrocarbon liquid, wherein the hydrocarbon liquid can be in an atomized form) are mixed with the carbon plasma in a gas-gas phase, thereby improving the mixing efficiency. The high-temperature carbon vapor jet and the hydrocarbon mixture can be uniformly mixed to produce acetylene in a very short time with low energy consumption. At the same time, the residence time of the hydrocarbon mixture in the reactor 20 is controlled within 1.5 to 3 ms, which can prevent carbon atoms from polymerizing to form carbon black, reduce the probability of side reactions, and help the reaction be more biased towards acetylene production, thereby improving the acetylene yield. Alternatively, a large amount of hydrogen drives the coal powder to be quickly and uniformly mixed with the high-enthalpy carbon vapor jet, eliminating the dispersion problem in the process of pyrolysis of coal powder to produce acetylene. The residence time of hydrogen, coal powder (containing hydrocarbon solid powder), and high-enthalpy carbon plasma in the reactor 20 is controlled within 2.5 to 5 ms, thereby shortening the reaction time and improving the acetylene yield. At the same time, the surface area of ​​the reactor 20 is reduced, thereby reducing the heat loss of the reactor 20. Among them, the amount of chain hydrocarbon added in the supplementary carbon source is based on the carbon content of the carbon steam jet, and the mass flow ratio of carbon in the hydrocarbon-containing gas that can be cracked into small hydrocarbon molecules to the gaseous phase carbon in the carbon steam jet is 0 to 3, that is, the molar flow rate of carbon in the carbon steam jet is set to 1, then the molar flow rate of carbon in the input hydrocarbon-containing gas can be 0.3, 0.5, 0.8, 1, 1.2, 1.5, 2, etc.

[0069] To control the mixing and cracking reaction of the reaction gas and the carbon vapor jet within 1.5-3 ms, the flow rates of the reaction gas and carbon vapor jet and the quenching position of the quench water can be controlled so that their residence time in reactor 20 is no longer than 3 ms. In some embodiments, the carbon vapor jet has a flow rate of approximately 300 m / sec, and the flow rate of the supplementary carbon source hydrocarbon gas (in a cold state) is approximately 100 m / sec. This allows for rapid and uniform mixing of the two. After mixing with hydrogen, the flow rate within the reaction chamber is approximately 300 m / sec, and the residence time in reactor 20 is controlled within 1.5-3 ms. The length of the mixing reaction section of the reaction chamber is 450-900 mm. The reaction is terminated by quenching the product outlet of reactor 20. Specifically, the product can be cooled to below 500 K to freeze the reaction.

[0070] To improve the mixing efficiency of the two gases, in some embodiments, the reaction gas is introduced in a direction intersecting the central axis of the carbon vapor jet. The ratio of the momentum of the reaction gas entering the reaction chamber perpendicular to the flow direction of the carbon vapor jet to the momentum of the carbon vapor jet is controlled to be M, and M is preferably 0.5-2. In this way, the two gases can be efficiently mixed, and the mixing speed can generally be controlled within 1ms. In other embodiments, the reaction gas is introduced into the reaction chamber at a direction offset from the reaction chamber axis, forming a rotating flow within the reaction chamber. This can increase the mixing contact area of ​​the two groups of gases, improve the mixing efficiency, and simultaneously prevent the carbon vapor jet from flowing toward the inner wall of the reaction chamber 201 and forming coke on the inner wall of the reaction chamber due to the collision of the two gases. In addition, the rotating gas in the reaction chamber 201 can also cause the ungasified carbon powder entering the reaction chamber 201 to move toward the wall of the reaction chamber 201. On the one hand, it is beneficial to isolate the mass transfer to the inner wall of the reaction chamber 201, thereby reducing coking. At the same time, it can also flush the inner wall of the reaction chamber 201, thereby eliminating coking on the inner wall of the reaction chamber 201; on the other hand, it can also reduce heat transfer to the inner wall of the reaction chamber 201 and reduce energy loss.

[0071] In one embodiment, an oxidant is uniformly introduced along the periphery of the reaction chamber; the oxidant includes gaseous or liquid H2O, CO2, O2, etc., or a mixture thereof. Under pressure, the oxidant passes through the porous structure of the reaction chamber wall and enters the vicinity of the inner wall surface of the reaction chamber. The oxidant reacts with CH4 small molecules near the inner wall surface of the reaction chamber to generate stable H2 and CO gas molecules, thereby suppressing the coking of CH4 small molecules on the inner wall surface of the reaction chamber and cooling the reaction chamber wall.

[0072] Another embodiment of the present application provides an arc plasma reactor 100. Figures 2 to 7 illustrate a specific embodiment of the arc plasma reactor 100. This arc plasma reactor 100 not only enables the aforementioned acetylene production method but also further promotes carbon powder gasification, reduces energy loss, and prevents coking.

[0073] Referring to Figures 2 and 5 , the arc plasma reactor 100 includes a reactor 20 and a plasma torch 10. A reaction chamber 201 is formed within the reactor 20, open at both ends. Multiple media delivery nozzles are positioned on the sidewalls of the reaction chamber 201 for supplying reactant gases. The reactor is typically positioned vertically or horizontally. In the illustrated embodiment, the reaction chamber 201 extends vertically, with its upper end being the first end and its lower end being the second end, with the first and second ends positioned opposite each other. The plasma torch 10 includes a first electrode accommodating chamber, a first solid powder nozzle 4, and an arc channel 101. The arc channel 101 is coaxially arranged with the reaction chamber 201, with one end communicating with the first electrode accommodating chamber and the first solid powder nozzle 4 and the other end communicating with an open end of the reaction chamber 201. The arc channel 101 is used to generate an arc and vaporize carbon powder. A first arc electrode 7 is positioned within the first electrode accommodating chamber, and the first solid powder nozzle is used to deliver carbon powder into the arc channel 101. Wherein, a plurality of electrode holes are provided on the side wall of the reaction chamber, and a second arc electrode with a polarity opposite to that of the first arc electrode is provided in each of the electrode holes.

[0074] In the embodiment of the present application, the medium delivery nozzle can coincide with the electrode hole: that is, the reaction gas can be input through the electrode hole (as shown in Figure 2); while the medium delivery nozzle coincides with the electrode hole, there can still be a gas supplementary carbon source nozzle 2 (as shown in Figure 3); while the medium delivery nozzle coincides with the electrode hole, there can still be a second solid powder nozzle 5 (as shown in Figure 4).

[0075] In one embodiment of the present application, one end of the arc channel 101 is in communication with the upper opening of the reaction chamber 201. The arc channel 101 has an outlet end connected to the upper end of the reaction chamber 201 and an inlet end disposed opposite the outlet end. The arc channel 101 includes an arc channel inlet 1 adjacent to the inlet end. In the feeding direction (the direction of carbon powder flow), the cross-section of the arc channel inlet 1 is gradually reduced (Figure 2), and the downstream portion thereof transitions from a straight tube to a gradually larger diameter (Figures 2 and 3).

[0076] In the technical solution of the present application, the plasma torch 10 is connected to the reactor 20, and the arc channel inlet 1 of the plasma torch 10 is tapered in the direction of the carbon powder flow (Figure 2). In this way, when the plasma working gas carrying carbon powder enters the arc channel 101, the setting of the contraction port here can concentrate the carbon powder therein to the axis of the plasma torch 10, so that most of the carbon powder is concentrated in the arc, which helps to improve the carbon powder gasification rate. In the arc channel, as the carbon powder is rapidly gasified, the volume increases sharply, and the arc channel is gradually enlarged in the direction of the carbon plasma flow, reducing the pressure and plasma flow speed in the plasma torch, increasing the residence time of the carbon powder in the plasma, and improving the carbon powder gasification rate. In addition, the plasma torch 10 can also be integrated with the reactor 20.

[0077] Referring to Figures 3, 5 and 6, in this embodiment, the reaction chamber 201 is cylindrical, and the plasma torch 10 is arranged at the first end of the reactor 20 and is coaxially arranged with the reactor 20. In this way, the carbon vapor jet ejected from the outlet end of the plasma torch 10 can enter the reaction chamber 201 along the central axis direction of the reactor 20; the plasma torch nozzle diameter d1 is less than or equal to the reaction chamber inlet diameter d2.

[0078] The arc channel 101 of this embodiment includes an arc channel entrance 1 and an arc channel connected between the arc channel entrance 1 and the reaction chamber 201. The plasma torch 10 further includes a first arc electrode 7, which is disposed at the center of the arc channel entrance 1 and extends along its central axis, with its end extending toward the vicinity of the arc channel entrance. This ensures that the arc column 6 formed by the first arc electrode 7 is primarily located within the arc channel, with a smaller portion located within the reaction chamber 201. The arc channel tube wall 102 is typically water-cooled.

[0079] Specifically, one or more first electrode accommodating chambers and first arc electrodes 7 of the plasma torch 10 may be provided.

[0080] Referring to Figure 3, in some embodiments, the plasma torch 10 is provided with a first electrode accommodating cavity and a first arc electrode 7, and multiple first solid powder nozzles 4 are provided. The number of the first solid powder nozzles 4 is ≥3, and they are located near the entrance of the arc channel and are symmetrically and evenly distributed around the axis of the arc channel. The angle β between the axis of the first solid powder nozzle 4 and the axis of the arc channel is 10° to 90°.

[0081] In one embodiment, the arc channel inlet 1 is an annular cavity. Gas-carried carbon powder is transported into the arc channel from multiple first solid powder nozzles 4. Driven by the airflow, the carbon powder is uniformly injected from the periphery of the arc into the arc ionization channel (i.e., the arc column 6). The carbon powder is heated and vaporized by the plasma within the arc ionization channel. The carbon powder that does not enter the arc column isolates the arc from radiation and convection heat transfer to the channel wall. In one embodiment, the arc channel is a circular tube with an aspect ratio greater than 5. The first arc electrode 7 is made of tungsten alloy or graphite and is protected by an inert gas such as Ar or N2. For example, a hole is provided at the center of the arc channel inlet 1, connecting to the arc channel. The first arc electrode 7 is disposed therein, spaced from the hole wall, and an inert gas circulates through the hole. The first arc electrode 7 is water-cooled.

[0082] Referring to Figures 4 and 7, in some embodiments, the plasma torch 10 is provided with multiple first arc electrodes 7, and the number of first arc electrodes 7 is ≥3; the first arc electrodes 7 are evenly distributed circumferentially around the axis of the arc channel, and a first solid powder nozzle 4 is provided, the first solid powder nozzle 4 is located at the center of the multiple first arc electrodes 7, coaxial with the arc channel, and the angle γ between the electrode axis and the first solid powder nozzle (arc channel axis) is 10° to 90°; the arc starts from the multiple electrodes and converges at the axis of the arc channel, and the carbon powder is injected into the arc ionization channel (i.e., the arc column 6) along the axis.

[0083] See Figures 2, 3, and 5. In one embodiment, in addition to the single plasma torch 10, a plurality of electrode holes 3 are provided on the sidewall of the reaction chamber 201. The plurality of electrode holes 3 are spaced apart along the circumference of the reaction chamber 201. A second arc electrode 8 having a polarity opposite to that of the first arc electrode is disposed within each electrode hole 3. Each electrode 8 is entirely housed within the electrode hole 3, with the top of the second arc electrode 8 facing into the reaction chamber 201. In one embodiment, the top of each second arc electrode 8 does not extend beyond the inner wall of the reaction chamber 201 to prevent coking. The electrode hole 3 is typically a circular hole. The second arc electrode 8 is disposed at the center of the electrode hole 3 and spaced apart from the hole wall. A gas shield is provided around the second arc electrode 8 to isolate and insulate it from the wall of the reaction chamber 201 and prevent coking. The plasma torch 10 is a cathode transferred arc plasma torch (the first arc electrode 7 is a cathode), and the plurality of second arc electrodes 8 are anodes. When the plasma torch 10 has multiple first arc electrodes 7, the number of the first arc electrodes 7 is the same as the number of the second arc electrodes 8; in the specific electrical connection, the negative poles of multiple independent constant current power supplies are commonly connected to the single first arc electrode 7 of the cathode transferred arc plasma torch 10, or the negative poles of multiple independent constant current power supplies are respectively connected to the multiple first arc electrodes 7; the positive poles of the independent constant current power supplies are respectively connected to the multiple anode second arc electrodes 8.

[0084] The angle a between the electrode hole axis and the reactor axis is between 30° and 150°, preferably between 60° and 120°; the axes of multiple electrode holes intersect a tangential circle coaxial with the reaction chamber in the cross section of the reactor, and the diameter of the tangential circle is less than 1 / 3 of the diameter of the reaction chamber. The gas flow direction of the electrode hole generates axial flow, radial flow and tangential flow.

[0085] When using the present arc plasma torch reaction device 100 to produce acetylene, hydrogen, a mixed gas, or a recycled supplemental hydrogen / carbon source can be input through the electrode holes 3; the mixed gas ejected from the electrode holes rapidly mixes and reacts with the carbon vapor jet to produce acetylene. In this way, the mixed gas or recycled supplemental hydrogen / carbon source can be used as a shielding gas to protect the second arc electrode 8, and can also be used to input a hydrocarbon mixed gas to help produce acetylene, reducing the number of dedicated gas input holes and simplifying the device structure. Each electrode hole 3 is located near the first end (see Figure 2). In this way, the shielding gas or hydrocarbon mixed gas ejected from the electrode hole 3 can eliminate the backflow of the carbon vapor jet ejected from the outlet end of the plasma torch 10, thereby preventing coking at the outlet end of the plasma torch 10 or the first end of the reaction chamber 201.

[0086] A gas-supplemented carbon source nozzle 2 can also be provided (see FIG3 ). The gas-supplemented carbon source nozzles 2 are spaced apart along the circumferential direction of the reaction chamber 201. The angle α' between the axis of the gas-supplemented carbon source nozzle 2 and the axis of the reactor is between 30° and 150°. The projection of the nozzle axis on the cross section of the reaction chamber is tangent to the concentric circle in the reaction chamber. The nozzle gas flow direction generates axial flow, radial flow, and tangential flow in the same direction as the carbon vapor jet. The hydrocarbon mixed gas ejected from the gas-supplemented carbon source nozzle 2 rapidly mixes with the carbon vapor jet to react and generate acetylene. In this arrangement, hydrogen is input into each electrode hole 3 to prevent the arc from breaking through the electrode hole wall.

[0087] The carbon source gas supplement nozzle 2 can be positioned at the first end of the reaction chamber near the outlet of the plasma torch arc channel. The chain hydrocarbon or hydrocarbon-containing mixed gas ejected from the carbon source gas supplement nozzle 2 can eliminate the backflow of the carbon vapor jet ejected from the outlet of the plasma torch 10, thereby preventing coking at the outlet of the plasma torch 10 or at the first end of the reaction chamber 201. The carbon source gas supplement nozzle 2 can also be positioned in the same plane as the electrode aperture or downstream of the electrode aperture.

[0088] The gas-supplemented carbon source nozzle 2 can also be an atomizing nozzle, which sprays liquid chain hydrocarbons; hydrogen is used to atomize the liquid.

[0089] When the gas-supplemented carbon source nozzle 2 is used to spray a hydrocarbon-containing mixed gas or atomize a hydrocarbon-containing liquid, the diameter of the tangential circle intersecting axially with the gas-supplemented carbon source nozzle 2 is less than 1 / 2 of the reaction chamber diameter, preferably not greater than 1 / 3 of the reaction chamber diameter, and less than the outlet diameter of the plasma torch arc channel.

[0090] 4 and 7 , a second solid powder nozzle 5 is uniformly arranged around the axis of the reaction chamber, and the axial position is close to the arc channel entrance ( FIG. 4 ). The nozzle axis deviates from the arc channel axis in the same direction, and the intersection and tangent circle are larger than the diameter of the plasma torch arc channel. The hydrocarbon-containing solid powder is sprayed around the arc column, isolating the arc from the heat transfer to the arc channel wall and constraining the arc. Alternatively, the nozzle axis intersects the reactor axis, and the pulverized coal slowly enters the chamber along the four sides of the reaction chamber to surround the plasma torch carbon vapor jet. Alternatively, the axial position is close to the upstream and downstream of the second arc electrode (as shown in the position of the medium nozzle in FIG. 3 ), and hydrogen or other gas transports the pulverized coal into the reactor. The nozzle axis deviates from the arc channel axis in the same direction, and the intersection and tangent circle are smaller than the diameter of the plasma torch arc channel outlet. The hydrocarbon-containing solid powder is sprayed to mix with the torch carbon vapor jet. The high-speed plasma jet ejected from the electrode hole causes the solid powder, carbon vapor jet and hydrogen to quickly and evenly mix, reacting to produce acetylene. The angle γ between the axis of the second solid powder nozzle 5 and the axis of the reaction chamber is between 20° and 90°.

[0091] In addition, a plurality of cooling medium atomizing nozzles 9 are provided on the sidewall of the reaction chamber 201. The plurality of cooling medium atomizing nozzles 9 are arranged near the second end and along the circumference of the reaction chamber 201. This allows the gas at the second end to be rapidly cooled to terminate the cracking reaction.

[0092] Water cooling pipes can be provided around the inner wall surface to provide forced cooling when necessary. The wall temperature of the reactor 20 is controlled to be less than 1100K.

[0093] Furthermore, the inner wall of the reaction chamber is constructed of high-temperature and wear-resistant materials, such as corundum, silicon carbide, or high-temperature metals, and features a reticular, interconnected, microporous structure. Under pressure, an oxidizing protective agent penetrates the chamber through the interconnected micropores within the chamber wall. The agent absorbs heat within the tube wall, cooling the chamber wall. The liquid protective agent also acts as an evaporative cooling agent. The oxidizing protective agent reacts with small CH molecules near the chamber wall to form stable molecules, inhibiting the formation of coking on the chamber wall caused by vaporized carbon powder CH molecules and reducing the temperature near the wall.

[0094] Based on the above embodiment, the present application further proposes another embodiment of a method for preparing acetylene. The method for preparing acetylene comprises the following steps:

[0095] Step S100, carbon powder is carried by gas and fed into the arc channel 101 from the inlet end, and the arc heats the carbon powder to gasify and form a carbon vapor jet;

[0096] Step S200: Inputting into the reaction chamber 201: 1) hydrogen and a hydrocarbon-containing gas, causing the mixed gas to mix with the carbon vapor jet within 1.5 to 3 ms and undergo a cracking reaction to obtain acetylene; 2) hydrogen and an atomized hydrocarbon liquid, causing the hydrogen and the atomized hydrocarbon liquid to mix with the carbon vapor jet within 2 to 4 ms and undergo a cracking reaction to obtain acetylene; 3) hydrogen and a hydrocarbon-containing solid powder (i.e., a solid powder supplementing the carbon source), causing the hydrogen and the hydrocarbon-containing solid powder to mix with the carbon vapor jet within 2.5 to 5 ms and undergo a cracking reaction to obtain acetylene;

[0097] In step S300, gaseous O2, H2O, CO2, or a mixture thereof is fed into the reaction chamber 201 adjacent to the wall. The oxidant reacts with CH small molecules near the reaction chamber wall to form stable molecules, thereby suppressing the coking of CH small molecules from the gasified carbon powder on the reaction chamber wall and reducing the temperature near the wall.

[0098] The technical solution of the present application is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the following embodiments are only used to explain the present application and are not used to limit the present application.

[0099] Example 1

[0100] An arc plasma reaction device 100 as shown in FIG2 is provided. The arc plasma reaction device 100 includes a reactor 20 and a plasma torch 10; the plasma torch 10 is a cathode transferred arc plasma torch, an arc channel 101 is formed inside the plasma torch, one end of the arc channel 101 is openly connected to one end of the reaction chamber 201, and the arc channel 101 includes an arc channel inlet 1 adjacent to an inlet end away from the reaction chamber 201; in the feeding direction, the cross-section of the arc channel inlet 1 is gradually reduced, and the cross-section of the arc channel inlet 1 is gradually increased downstream; a first electrode 7 is located at the arc channel inlet. The reactor 20 has a first opening and a second opening coaxial with the arc channel, and the electrode 7 is a cathode. A reaction chamber 201 with two ends opened is formed inside the reactor 20. Six electrode holes 3 are located at the end close to the connection between the reaction chamber and the plasma torch. The axes of the electrode holes 3 are perpendicular to the axis of the reaction chamber and the angle α is 70° (Figure 3). The diameter of the tangent circle intersected by the axes of the electrode holes 3 is 1 / 6 of the diameter d2 at the outlet of the plasma torch. A second arc electrode 8 is installed in each electrode hole, and the second arc electrode 8 is an anode. The first arc electrode 7 and the second arc electrode 8 are both protected by protective gas, and the arc channel wall is cooled by liquid water.

[0101] The carbon powder is coal coke powder, pre-dried to a volatile matter content of less than 1%, a carbon content of 95% after deashing, and an average primary particle size of less than 20 μm. The plasma working gas is air. Carbon monoxide and carbon powder are introduced into the arc channel 101 from the inlet end 4 of the plasma torch 10 at a mass flow rate ratio of 20:1 between the carbon powder and the plasma working gas. An arc is initiated with an arc current of 600 A and a voltage of 1200 V. The arc heats the carbon vapor jet, forming a carbon vapor jet that enters the reaction chamber 201. The jet has an average temperature greater than 6000 K and a flow rate of approximately 600 m / sec. The carbon vapor jet has a gasification rate of 30% and a specific enthalpy of approximately 60 MJ / kg.

[0102] A hydrocarbon-containing mixed gas is fed into the reaction chamber 201 from the electrode hole 3 at a flow rate of ~80 m / sec (cold state) to mix with the carbon vapor jet. The momentum and total mass of the mixed gas are greater than those of the carbon vapor jet. The mixing and reaction control time is ~2 ms. The gaseous carbon, hydrocarbon gas and hydrogen in the carbon vapor jet react to produce acetylene.

[0103] The hydrocarbon-containing mixed gas is coke oven gas, which contains 25% methane, 55% hydrogen, and approximately 20% carbon monoxide. The coke oven gas is pre-purified and dehydrated. The coke oven gas input is four times the flow rate of the gaseous carbon in the carbon steam jet. After mixing, the total hydrogen to gaseous carbon ratio is 4.2. The hydrocarbon-containing mixed gas can also be a mixture of methane and hydrogen, or it can be a mixture of hydrocarbons separated from the reaction product and then supplemented with natural gas and hydrogen.

[0104] The acetylene yield (molar ratio of product acetylene carbon to total carbon in the gas phase before the reaction) is 80%, the carbon conversion rate (gaseous carbon / total carbon, excluding CO) is 59%; the plasma torch thermal efficiency is 96%, and the acetylene energy consumption is 9.2 kWh / kg.

[0105] Example 2

[0106] An arc plasma reaction device 100 as shown in FIG3 is provided, wherein the difference from FIG3 is that the nozzle 2 is located downstream (below) the electrode hole 3. The arc plasma reaction device 100 includes a reactor 20 and a plasma torch 10; the plasma torch 10 is a cathode transferred arc plasma torch, an arc channel 101 is formed inside the plasma torch, one end of the arc channel 101 is connected to an opening at one end of the reaction chamber 201; the arc channel 101 includes an arc channel inlet 1 adjacent to an inlet end away from the reaction chamber 201; in the feeding direction, the cross section of the arc channel inlet 1 is gradually reduced, and the cross section of the arc channel is gradually increased downstream thereof; the first electrode 7 is located at the arc channel inlet, coaxial with the arc channel, and the electrode 7 is a cathode; a reaction chamber 201 with two ends opened is formed inside the reactor 20; six first solid powder nozzles 4 are located near the end connected to the reaction chamber and the plasma torch, surrounding The reaction chamber wall is evenly distributed around the nozzle 4, and the angle α between the axis of the nozzle 4 and the axis of the arc channel is not 60°; the gas nozzle 2 is located downstream (below) the electrode hole 3, and the angle α' between the axis of the gas nozzle 2 and the axis of the reaction chamber is 90°. The diameter d3 of the tangent circle tangent to the axis of the nozzle 2 is the diameter at the outlet of the plasma torch; the six electrode holes 3 are located upstream of the nozzle 2, evenly distributed around the reaction chamber wall, and have an angular difference of 15° with the nozzle 2. The axial spacing between the electrode hole 3 and the nozzle 2 is less than the radius of the reaction chamber, and the angle α between the axis of the electrode hole 3 and the axis of the reaction chamber is 70°. The axis of the electrode hole 3 intersects with the axis of the reaction chamber. A second electrode 8 is installed in each electrode hole, and the electrode 8 is an anode. The arc electrode 7 and the anode electrode 8 are both protected by protective gas, and the arc channel wall and the anode wall are water-cooled.

[0107] The carbon powder is anthracite, devolatilized to a volatile content of less than 0.2%, and granulated to a particle size of 30 to 50 μm. The plasma working gas is oxygen. Carbon monoxide and carbon black are introduced into the arc channel 101 from the inlet of the plasma torch 10 at a mass flow ratio of 20:1 between the carbon powder and the plasma working gas. An arc is initiated with an arc current of approximately 600 A and a voltage of 1200 V. The arc heats the carbon vapor jet, forming a carbon vapor jet with an average temperature exceeding 6000 K and a flow rate of approximately 600 m / sec. The carbon vapor jet has a gasification rate of 30% and a specific enthalpy of approximately 55 MJ / kg.

[0108] Hydrogen is fed into the reaction chamber 201 from the electrode hole 3 at a flow rate of 200 m / sec (cold state) to mix with the carbon vapor jet to form a carbon vapor jet-hydrogen mixture; natural gas is fed into the reaction chamber 201 from the gas supplement carbon source nozzle 2 at a flow rate of 200 m / sec to mix with the carbon vapor jet-hydrogen mixture; the total mixing and reaction control time is ~2 ms, and the gaseous carbon in the carbon vapor jet undergoes a cracking reaction to produce acetylene.

[0109] The molar flow ratio of the natural gas to the gas phase carbon in the carbon vapor jet input into the reaction chamber is 1.5 / 1; the molar flow ratio of the natural gas to the hydrogen is 1.5 / 1; and the total hydrogen-carbon (gas phase) ratio after mixing is approximately 4 / 1.

[0110] The acetylene yield (the molar ratio of product acetylene carbon to total carbon in the gas phase before the reaction) is 75%, and the acetylene energy consumption is about 9.0 kWh / kg.

[0111] Example 3

[0112] An arc plasma reaction device 100 as shown in FIG4 is provided. The arc plasma reaction device 100 includes a reactor 20 and a plasma torch 10; the plasma torch 10 is a cathode transferred arc plasma torch, an arc channel 101 is formed inside the plasma torch, one end of the arc channel 101 is connected to an opening at one end of the reaction chamber 201, the arc channel 101 includes an arc channel inlet 1 adjacent to an inlet end away from the reaction chamber 201, and in the feeding direction, the cross section of the arc channel inlet 1 is gradually reduced; a reaction chamber 201 with two ends open is formed inside the reactor 20; the arc channel and the reaction chamber have the same diameter; the first solid powder nozzle 4 is coaxial with the arc channel; six first arc electrodes 7 are symmetrically and evenly distributed around the axis of the reaction chamber, and the angle γ' between the axis of the electrode 7 and the axis of the reaction chamber is 30°; six second solid powder nozzles 5 are located near the end where the reaction chamber is connected to the plasma torch and are evenly distributed around the wall of the reaction chamber, and the nozzles can be rectangular. The reactor has a circumferential width w1 greater than an axial height w2. The axis of the second solid powder nozzle 5 is perpendicular to the axis of the reaction chamber and deflected in the same direction to be tangent to the tangent circle of the arc channel cross section (top view, the tangent circle is not shown in Figure 7). Six electrode holes 3 are located downstream of the second solid powder nozzle and evenly distributed around the reaction chamber wall. The axes of the electrode holes 3 are perpendicular to the axis of the reaction chamber (the angle α between the electrode hole axis and the reaction chamber axis is 90°). The diameter d3 of the tangent circle d3 (Figure 5) of the axis of the electrode hole 3 tangent to the reaction chamber is less than 1 / 6 of the diameter of the reaction chamber at the outlet of the plasma torch, and the axis deviates from the direction of the radial ray of the reaction chamber on the same side as the second solid powder nozzle. An electrode 8 is installed in each electrode hole, and the electrode 8 is an anode. The arc electrode 7 and the anode electrode 8 are both protected by protective gas, the arc channel wall is water-cooled, and the reaction chamber wall has a mesh-like interconnected microporous structure. The reaction chamber wall is cooled by liquid water evaporation, and oxygen is introduced into the wall.

[0113] Carbon powder is carried by oxygen and delivered into the first solid powder nozzle 4 and into the arc channel 101. The carbon powder is char powder after coal pyrolysis in this reaction, with a volatile matter content of less than 0.5%, a carbon content of greater than 96% after acid-base deashing, and a particle size of less than 20 μm. The mass flow ratio of the carbon powder to the gas conveying the carbon powder is 20 / 1, and the mass flow ratio of the coal powder to the gas conveying the coal powder is 20 / 1.

[0114] The coal powder is evenly distributed and carried by air into six second solid powder nozzles 5; the coal powder rotates along the arc channel wall. The bituminous coal has a volatile content of 38-42% and a carbon content of 85%. After drying, the ground particles have an average size of less than 35nm.

[0115] An arc is initiated, wherein the arc current is approximately 600A and the voltage is approximately 1350V; the arc heats to form a carbon vapor jet with an average temperature greater than 6500K and a flow rate of approximately 600m / sec; in the carbon vapor jet, the gasification rate of the carbon powder is 33%, and the specific enthalpy of the carbon vapor jet is approximately 60MJ / kg.

[0116] Hydrogen is fed into the reaction chamber 201 from the electrode hole 3 at a flow rate of 250 m / sec (cold state), driving the mixing of pulverized coal and the carbon vapor jet. The momentum of the hydrogen in the electrode hole after being heated by the anode arc is greater than the momentum of the carbon vapor jet. The total mixing and reaction control time is ~3 ms. The gaseous carbon in the carbon vapor jet reacts with the small hydrocarbon molecules cracked from the pulverized coal and the hydrogen input from the electrode hole to produce acetylene.

[0117] Among them, the carbon powder flow rate is 150kg / h, the coal powder flow rate is 300kg / h, and the hydrogen flow rate (circulation) input to the reactor is 1900Nm 3 / h; reactor power 810kW; acetylene production 0.8t / h, acetylene energy consumption 10kWh / kg, hydrogen production 120Nm 3 / h, CO production 60Nm 3 / h.

[0118] The above descriptions are merely examples of the present application and are not intended to limit the scope of the present invention. The data listed are subject to significant variation due to process conditions, raw material variations, and reactor conditions. Any equivalent structural transformations made within the scope of the present application, using the present specification and drawings, or direct or indirect application in other related technical fields, are included within the scope of the present application.

Claims

1. A method for preparing acetylene, wherein: The preparation method of acetylene comprises the following steps: S1, feeding gas carrying carbon powder into an arc plasma torch of a plasma reactor, and heating the carbon powder with the arc to gasify the carbon powder to form a carbon vapor jet; S2, inputting a reaction gas into the plasma reactor so that the reaction gas and the carbon vapor jet are mixed and cracked to obtain acetylene, wherein the reaction gas includes hydrogen or a mixture of hydrogen and a hydrocarbon-containing compound.

2. The method for preparing acetylene according to claim 1, wherein: In step S1, the average enthalpy of the carbon steam jet is 30-80 MJ / kg.

3. The method for preparing acetylene according to claim 1, wherein: In the step S1, the ratio N of the mass flow rate of the carbon powder to the mass flow rate of the gas input into the plasma torch is greater than 1.

4. The method for preparing acetylene according to claim 1, wherein: The ratio of the momentum of the reaction gas in the direction perpendicular to the flow direction of the carbon steam jet to the momentum of the carbon steam jet is M, where M=0.2-5.

5. The method for preparing acetylene according to claim 1, wherein: The hydrocarbon-containing compound in step S2 includes at least one of hydrocarbon-containing gas, hydrocarbon-containing liquid, and hydrocarbon-containing solid powder. The hydrocarbon-containing solid powder includes coal powder, waste resin powder, or waste plastic powder. The volatile matter of the coal powder is greater than 20%.

6. The method for preparing acetylene according to claim 1, wherein: The step S2 further includes inputting an oxidant; the oxidant includes gaseous or liquid H2O, CO2, O2; and / or, In the step S1, the carbon powder includes coal powder, coal-made coke powder, blue carbon powder, petroleum coke powder, waste resin powder, waste plastic powder or carbon powder discharged from a plasma reactor; and / or, The mass content of hydrogen in the carbon powder is not more than 1.5%; and / or, The gas includes one or more of oxygen, carbon monoxide, carbon dioxide, argon, nitrogen, and air; and / or, The hydrogen-to-carbon molar ratio (H / C) of the total gas phase in the plasma reactor is 3-8.

7. An arc plasma reaction device, wherein: The arc plasma reaction device is applied to the method for preparing acetylene according to any one of claims 1 to 6, comprising: A reactor, wherein a reaction chamber with openings at both ends is formed inside, and a plurality of medium delivery nozzles are arranged on the side wall of the reaction chamber for inputting reaction gas; and A plasma torch, the plasma torch comprising a first electrode accommodating chamber, a first solid powder nozzle and an arc channel, the arc channel is coaxially arranged with the reaction chamber, one end of the arc channel is in communication with the first electrode accommodating chamber and the first solid powder nozzle, and the other end is in communication with an opening at one end of the reaction chamber, a first arc electrode is arranged in the first electrode accommodating chamber, and the first solid powder nozzle is used to deliver carbon powder into the arc channel; Wherein, a plurality of electrode holes are arranged on the side wall of the reaction chamber, and a second arc electrode having a polarity opposite to that of the first arc electrode is arranged in each of the electrode holes.

8. The arc plasma reaction device according to claim 7, wherein: The multiple medium delivery nozzles are evenly arranged along the circumferential direction of the reaction chamber, and the axes of the multiple medium delivery nozzles intersect a circle in the cross section of the reactor and coaxial with the reaction chamber, and the diameter of the circle is less than 1 / 3 of the diameter of the reaction chamber; and / or, The multiple electrode holes are arranged at intervals along the circumferential direction of the reaction chamber, and the angle α between the axis of each of the multiple electrode holes and the central axis of the reaction chamber is 30° to 150°, and the axis of the multiple electrode holes cuts a circle coaxial with the reaction chamber in the cross section of the reactor, and the diameter of the circle is less than 1 / 3 of the diameter of the reaction chamber; and / or The plurality of medium delivery nozzles coincide with the plurality of electrode holes.

9. The arc plasma reaction device according to claim 7, wherein: The first electrode accommodating chamber is provided with one, and the first electrode accommodating chamber is coaxially arranged with the reactor; at the same time, there are multiple first solid powder nozzles, which are evenly distributed around the axis of the arc channel, and the angle β between the axis of the first solid powder nozzle and the axis of the first arc electrode is 10° to 90°; or, There are multiple first electrode accommodating cavities, the multiple first arc electrodes have the same polarity, and the multiple first electrode accommodating cavities are evenly distributed around the axis of the arc channel. The angle γ between the axes of the multiple first arc electrodes and the axis of the arc channel is 10° to 90°; at the same time, there is one first solid powder nozzle, and the axis of the first solid powder nozzle is coaxially arranged with the arc channel.

10. The arc plasma reaction device according to claim 7, wherein: A plurality of second solid powder nozzles are arranged on the side wall of the reaction chamber or around the plasma torch, the plurality of second solid powder nozzles are evenly arranged along the circumferential direction of the reaction chamber or the plasma torch, or the axial positions of the plurality of second solid powder nozzles are located between the first solid powder nozzle and the second arc electrode or below the second arc electrode, and / or, The inner wall of the arc channel is made of a high-resistance material; the inner wall of the reaction chamber is made of a porous material.

Images