Plasma generator for coal seam plasma gasification system

Abstract

According to the plasma generator for the coal seam plasma gasification system, different types of gasification agents can be input at the same time according to underground coal seam gasification conditions, the injection flow and composition of the gasification agents are controlled, and high-temperature high-activity particles with different proportions are generated; controllable gas-solid reaction and gas-gas reaction are further carried out in the coal seam, hydrogen and carbon monoxide gas in different proportions are converted, regulation and control are sensitive, the conversion efficiency is high, the production intensity is high, few by-products are generated, and environment friendliness is achieved; according to underground coal bed gasification conditions, carbon dioxide and liquid water can be injected at the same time, the injection proportion of the carbon dioxide and the liquid water is flexibly regulated and controlled, in-situ efficient and flexible gasification regulation and control of a coal bed are achieved, coal gas meeting the coal-based high-value product synthesis requirement can be directly produced, the process of a ground coal gas treatment system is shortened, the investment and operation cost is reduced, and the production efficiency is improved. The operability is high, and stable synthesis of coal-based high-value products can be guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of coal seam gasification, in particular to a plasma generator used in a coal seam plasma gasification system. Background Art

[0002] In-situ coal seam gasification (ISG) technology integrates well construction, coal mining, and conversion, transforming physical mining into chemical mining. This technology converts high-molecular-weight solid coal into low-molecular-weight synthesis gas and methane, eliminating the need for mechanical mining, transportation, washing, and furnace construction required for utilization. Consequently, it offers advantages such as safety, low investment, high efficiency, low pollution, and high returns. Currently, hydrogen and methane in coal seam gasification gas can be purified and separated on the surface before being used as fuel. More often, synthesis gas is used as the primary raw material to synthesize high-value coal-based products such as methane, methanol, and ethylene glycol, or the carbon monoxide in the synthesis gas is converted into hydrogen to produce hydrogen products. Both processes require on-site conversion equipment to regulate the hydrogen-to-carbon monoxide ratio to meet the synthesis or production requirements of the target product. This directly increases the process flow and complexity of the surface gas treatment system, increasing investment and operating costs, and reducing the cost advantages of ISG.

[0003] In principle, in-situ coal seam gasification can control the composition of the outlet gas by changing the composition and flow rate of the injected gasifying agent. However, the traditional in-situ combustion or gasification of coal seams is a self-heating reaction between dense underground coal seams and oxygen-containing gasifying agents and is controlled by semi-natural forces. At the same time, it is significantly affected by the influx of groundwater due to the collapse of the coal seam roof, resulting in large fluctuations in the gas composition and output. The control is slow and difficult to achieve, and the conversion efficiency is low and the production intensity is low. This has a serious impact on the synthesis of the target product on the ground, and may even prevent stable production. Therefore, traditional in-situ coal seam gasification uses the addition of a changing device on the ground to control the gas composition to meet the synthesis requirements of the target product.

[0004] Therefore, the current in-situ coalbed gasification process, aimed at synthesizing target products, is plagued by long processes, complex operations, and high investment and operating costs. Consequently, a new coalbed gasification method is urgently needed that can efficiently and flexibly control the gas composition to meet the stable production needs of modern coal-based high-value products.

[0005] The above information disclosed in the background technology section is only used to enhance understanding of the background of the present invention and therefore may contain information that does not constitute the prior art known to ordinary technicians in this field. Utility Model Content

[0006] The purpose of this utility model is to provide a plasma generator for a coal seam plasma gasification system, which can realize efficient and flexible in-situ gasification control of the coal seam, directly produce coal gas that meets the synthesis needs of coal-based high-value products, and shorten the process of the ground coal gas treatment system.

[0007] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0008] A plasma generator for a coal seam plasma gasification system is provided, comprising:

[0009] Plasma generator body;

[0010] The cathode assembly is arranged in the plasma generator body, and the cathode assembly includes:

[0011] The cathode head is a hollow metal part.

[0012] The cathode rod is a hollow tube that conducts electricity and cools the cathode head. One end of the cathode rod is connected to the cathode terminal, and the other end is threadedly connected to the cathode head.

[0013] The cathode coolant injection pipe passes through the cathode rod and goes deep into the cathode head so that the cathode head is filled with coolant to reduce the temperature.

[0014] A cathode coolant return pipe is connected to the cathode rod so that the coolant after heat exchange flows back through the cathode coolant return pipe to achieve coolant circulation injection;

[0015] A reaction medium injection assembly is provided in the plasma generator body and is used for injecting the reaction medium;

[0016] The anode assembly is arranged in the plasma generator body and is used to cooperate with the cathode assembly to start an arc after being energized to transform the reaction medium.

[0017] Optionally, the reaction medium injection assembly includes:

[0018] a gaseous reaction medium chamber comprising an injection end located on the left side of the plasma generator body and an outlet end flush with the left side of the cathode head; the gaseous reaction medium chamber gradually narrows from the injection end toward the outlet end and has a bell-mouth shape, so that the pressure of the gaseous reaction medium in the gaseous reaction medium chamber gradually increases due to the gradual reduction in volume; and a gaseous reaction medium injection port is provided at the injection end;

[0019] The medium outlet is connected to the outlet end and causes the volume of the gaseous reaction medium from the gaseous reaction medium chamber to increase sharply and the gas pressure to decrease so as to generate a pressure difference.

[0020] Optionally, the reaction medium injection assembly further comprises:

[0021] The liquid medium cavity is located between the gaseous reaction medium cavity and the outer annulus of the anode, and is in the shape of a right triangle with the gaseous reaction medium cavity. The liquid medium cavity is provided with at least one liquid medium capillary on one side of the gaseous reaction medium cavity;

[0022] A liquid medium injection port for injecting liquid medium is provided on the left side of the liquid medium cavity. The liquid medium injection port is located on the upper and lower sides of the reaction medium injection assembly and is connected to the liquid medium cavity. The liquid medium from the liquid medium capillary is discharged from the medium outlet via the pressure difference.

[0023] Optionally, the reaction medium injection assembly further includes: an atomizing plate, which is fixed on the cathode rod and arranged at the medium outlet to cooperate with the gaseous reaction medium to atomize the liquid medium to form atomized droplets, and the atomized droplets diffuse with the gaseous reaction medium to between the cathode and the anode.

[0024] Optionally, the anode assembly comprises:

[0025] an anode head connected to the right end of the plasma generator body through threads or bolts, with an annulus provided outside the anode head;

[0026] An anode terminal is electrically connected to the anode head, and discharges between the anode head and the cathode head to ionize the gaseous reaction medium and the atomized droplets to generate a high-temperature and highly active plasma;

[0027] an anode coolant injection pipe connected to one side of the annulus to introduce coolant into the annulus to cool the anode head;

[0028] The anode coolant return pipe is connected to the other side of the annulus to reflux the coolant after heat exchange, thereby realizing coolant circulation injection.

[0029] Optionally, the gaseous reaction medium injection ports are evenly arranged in two or more groups with the cathode rod as the symmetry axis and located on the left side of the gaseous reaction medium cavity, for evenly inputting the gaseous reaction medium into the gaseous reaction medium cavity.

[0030] Optionally, two or more capillaries from the liquid medium are evenly distributed along the gaseous reaction medium cavity, and a baffle for preventing liquid backflow is provided between the left side of the liquid medium cavity and the liquid medium injection port.

[0031] Optionally, the cathode coolant injection pipe, cathode coolant return pipe, anode coolant injection pipe and anode coolant return pipe are connected to the cooling medium injection port, and the gaseous reaction medium injection port and liquid medium injection port are respectively connected to the reaction medium injection port.

[0032] The above technical solution has at least the following beneficial effects:

[0033] A multi-media injection plasma generator tailored to underground coalbed gasification conditions allows for simultaneous input of different types of gasifying agents, and the injection flow and composition of the gasifying agents can be controlled to generate high-temperature, highly active particles in varying proportions. Controllable gas-solid and gas-gas reactions then occur in the coalbed, converting them into hydrogen and carbon monoxide gases in varying proportions. This process features sensitive regulation, high conversion efficiency, high production intensity, few by-products, and is environmentally friendly. Specifically tailored to underground coalbed gasification conditions, carbon dioxide and liquid water can be injected simultaneously, and the injection ratio of carbon dioxide and liquid water can be flexibly controlled, achieving efficient and flexible in-situ coalbed gasification control. This allows for direct production of coal gas that meets the synthesis requirements of coal-based high-value products, shortening the process of surface coal gas treatment systems and reducing investment and operating costs. The plasma generator is highly operational, ensuring the stable synthesis of coal-based high-value products, and further enhancing the cost advantage of in-situ coalbed gasification. This plasma generator can be used for the development and utilization of carbon-based energy sources such as coal, peat, oil shale, and heavy oil layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] 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. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0035] Figure 1 A schematic structural diagram of a plasma generator for a coal seam plasma gasification system provided in one embodiment of the present invention.

[0036] Figure 2 A schematic structural diagram of a plasma generator for a coal seam plasma gasification system provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0037] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but rather merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0041] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature specified as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of this utility model, "plurality" means two or more, unless otherwise specifically defined.

[0042] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; they can refer to direct connection or indirect connection through an intermediate medium; they can refer to internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0043] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Moreover, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0045] See also Figure 1-2 As shown, in one embodiment, a plasma generator for a coal seam plasma gasification system of the present invention includes:

[0046] The conversion channel 22 is formed by vertically passing through the overburden 23 and the upper edge of the coal seam 21 from the ground 24 and then gradually deflecting to the horizontal direction to form a non-vertical channel in the coal seam 21. The non-vertical channel extends a certain distance in the coal seam, and the other side is connected to the non-vertical channel by vertically passing through the overburden 23 and the coal seam from the ground 24;

[0047] The reaction assembly 25 comprises,

[0048] The reaction tube 27 is provided in the conversion channel 22. One end of the reaction tube 27 is connected to the reaction tube drive device 30 and the injection device on the ground, and the other end in the non-vertical channel is connected to the plasma generator 29. A coaxial injection pipe 28 is provided in the reaction tube 27. The injection pipe 28 encloses the reaction medium injection pipe, the cooling medium injection pipe and the power cable.

[0049] The reaction tube driving device 30 is installed on the ground to controllably move the reaction tube 27.

[0050] The injection device is connected to the reaction tube drive device 30 and the injection pipe 28 to control the injection amount of gaseous and liquid reaction media and the flow rate of the cooling medium inlet loop. The injection device is provided with multiple reaction medium injection ports, cooling medium injection ports, power cables and corresponding valves and switches.

[0051] a plasma generator 29 which generates high-temperature and highly reactive particles from a reaction medium supplied via an injection pipe 28 to convert the coal seam into coal gas;

[0052] The harvesting assembly 26 includes:

[0053] The recovery pipe 33 is connected to the conversion channel 22 to collect coal gas.

[0054] The comprehensive testing device 34 is installed on the surface of the recovery pipe 33 to test the composition, temperature and pressure of the recovered gas.

[0055] The flow rate testing device 35 is installed on the surface portion of the recovery pipe 33 to test the flow rate of the recovered gas.

[0056] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the plasma generator 29 is a multi-media injection plasma generator that simultaneously inputs different types of gasifying agents and controls the injection flow and composition of the gasifying agents, which produces high-temperature and high-activity particles in different proportions to cause controllable gas-solid reactions and gas-gas reactions in the coal seam to be converted into hydrogen and carbon monoxide gases in different proportions.

[0057] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the multi-media injection plasma generator injects carbon dioxide and liquid water, or hydrogen and liquid water.

[0058] In a preferred embodiment of the plasma generator for coal seam plasma gasification system, the plasma generator 29 comprises:

[0059] Plasma generator body 1;

[0060] The cathode assembly 3 is provided in the plasma generator body 1 and includes:

[0061] The cathode head 13 is a hollow metal part.

[0062] The cathode rod 12 is a hollow tube for conducting electricity and cooling the cathode head 13. One end of the cathode rod 12 is connected to the cathode terminal 14, and the other end is threadedly connected to the cathode head 13.

[0063] The cathode coolant injection pipe 15 passes through the cathode rod 12 and penetrates into the cathode head 13 so that the cathode head 13 is filled with coolant to reduce the temperature.

[0064] A cathode coolant return pipe 16 is connected to the cathode rod 12 so that the coolant after heat exchange flows back through the cathode coolant return pipe 16 to achieve coolant circulation injection;

[0065] The reaction medium injection assembly 2 is provided in the plasma generator body 1 and includes:

[0066] The gaseous reaction medium chamber 5 includes an injection end located on the left side of the plasma generator body 1 and an outlet end flush with the left side of the cathode head 13. The gaseous reaction medium chamber 5 gradually tapers from the injection end to the outlet end and has a bell-mouth shape, so that the gaseous reaction medium in the gaseous reaction medium chamber 5 gradually increases in pressure due to the gradual reduction in volume. The injection end is provided with a gaseous reaction medium injection port 9.

[0067] The medium outlet 6 is connected to the outlet end and causes the volume of the gaseous reaction medium from the gaseous reaction medium chamber 5 to increase sharply and the gas pressure to decrease to generate a pressure difference.

[0068] The liquid medium chamber 7 is located between the gaseous reaction medium chamber 5 and the outer annulus of the anode, and is in the shape of a right triangle with the gaseous reaction medium chamber 5. The liquid medium chamber 7 is provided with at least one liquid medium capillary 8 on one side of the gaseous reaction medium chamber 5. A liquid medium injection port 10 for injecting liquid medium is provided on the left side of the liquid medium chamber 7. The liquid medium injection port 10 is located on the upper and lower sides of the reaction medium injection assembly 2 and is connected to the liquid medium chamber 7. The liquid medium from the liquid medium capillary 8 is discharged from the medium outlet 6 via the pressure difference.

[0069] The atomizing plate 11 is fixed on the cathode rod 12 and arranged at the medium outlet 6 to cooperate with the gaseous reaction medium to atomize the liquid medium to form atomized droplets, and the atomized droplets diffuse with the gaseous reaction medium to between the cathode and the anode;

[0070] The anode assembly 4 is provided in the plasma generator body 1 and includes:

[0071] The anode head 17 is connected to the right end of the plasma generator body 1 by threads or bolts, and an annulus is provided outside the anode head 17.

[0072] The anode terminal 18 is electrically connected to the anode head 17. The anode head 17 and the cathode head 13 discharge and ionize the gaseous reaction medium and the atomized droplets to generate high-temperature and high-activity plasma.

[0073] Anode coolant injection pipe 19, which is connected to one side of the annulus to introduce coolant into the annulus to cool the anode head 17,

[0074] The anode coolant return pipe 20 is connected to the other side of the annulus to reflux the coolant after heat exchange, thereby realizing coolant circulation injection.

[0075] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the gaseous reaction medium injection port 9 is evenly arranged in two or more groups with the cathode rod 12 as the symmetry axis, and is located on the left side of the gaseous reaction medium chamber 5, for evenly inputting the gaseous reaction medium into the gaseous reaction medium chamber 5.

[0076] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, two or more liquid medium capillaries 8 are evenly distributed along the gaseous reaction medium cavity 5, and a baffle is provided between the left side of the liquid medium cavity 7 and the liquid medium injection port 10 to prevent liquid backflow.

[0077] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the cathode coolant injection pipe 15, the cathode coolant return pipe 16, the anode coolant injection pipe 19 and the anode coolant return pipe 20 are connected to the cooling medium injection port, and the gaseous reaction medium injection port 9 and the liquid medium injection port 10 are respectively connected to the reaction medium injection port.

[0078] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the injection device includes a gas medium injection device 31 and a liquid medium injection device 32 .

[0079] In a preferred embodiment of the plasma generator for a coal seam plasma gasification system, the reaction tube driving device 30 is connected to one end of the reaction tube 27 and moves the reaction tube 27 by extending and retracting, with the moving distance accurate to 0.1 m.

[0080] The conversion method of the coal seam plasma gasification system includes:

[0081] A non-vertical channel is formed in the coal seam after vertically passing through the overburden 23 and the upper edge of the coal seam 21 from the ground 24. The non-vertical channel extends a certain distance in the coal seam. On the other side, the ground 24 vertically passes through the overburden 23 and the coal seam 21 and connects with the non-vertical channel to form a conversion channel 22. A reaction tube 27 extends from the ground into the coal seam in the conversion channel 22. One end of the reaction tube 27 is connected to the reaction tube drive device 30 and the injection device on the ground, and the other end is connected to the plasma generator 29 on the ground and lowered into the coal seam 21. The plasma generator 29 is lowered into the conversion channel 22 by the reaction tube drive device 30 and extends into the coal seam to a horizontal distance of 5 to 50 meters to the recovery pipe 33.

[0082] A certain amount of carbon dioxide is injected by the gas medium injection device 31, and the plasma generator 29 is started. When the volume percentage of carbon monoxide in the outlet coal gas exceeds 5%, it indicates that the coal seam has started to gasify. The gas medium injection device 31 and the liquid medium injection device 32 respectively control the gas medium and liquid medium injection flow rates, gradually adjust the gas medium and liquid medium injection amount and the power of the plasma generator 29, and maintain the load of the plasma generator 29 between 10% and 50%, and then the coal seam gasification production begins.

[0083] For example, after a period of normal production, if the flow rate testing device 35 reports a continuous decrease in the outlet gas flow rate, this indicates that the coal seam conversion reaction intensity decreases as the reaction cavity increases. The reaction medium injection flow rate and the power of the plasma generator 29 are increased to increase the conversion reaction load to 60% to 100%. After a period of continued production, if the flow rate reported by the flow testing device 35 further decreases, it indicates that the coal seam covered by the plasma generator 29 and the recovery pipe 33 has been converted. The plasma generator 29 is kept in the activated state, and the reaction pipe 27 is moved back approximately 5 to 50 meters. After the reaction pipe 27 is completely retracted, the coal seam conversion production is continued. The production cycle is adjusted in this way. When the movement distance of the reaction pipe driving device 30 approaches the non-vertical section distance of the conversion channel 22, the power of the plasma generator 29 is turned off, the reaction medium injection is stopped, the cooling medium injection is maintained, and the reaction pipe 27 and the recovery pipe 33 are respectively withdrawn to the surface.

[0084] In one embodiment, the multi-media injection plasma generator 29 can simultaneously feed different types of gasifying agents and control their injection rate and composition to produce varying proportions of high-temperature, highly reactive particles. These particles then undergo controllable gas-solid and gas-gas reactions within the coal seam, converting them into varying proportions of hydrogen and carbon monoxide. This enables efficient and flexible in-situ coal seam gasification control, directly producing coal gas that meets the needs of synthesizing high-value coal-based products.

[0085] The gas-solid reaction is mainly:

[0086] C + H2O = CO + H2 (1)

[0087] C + CO2 = 2CO (2)

[0088] That is, the carbon elements in the coal seam react with high-temperature and highly active water vapor and carbon dioxide particles to form a gas-solid reaction, mainly converting into carbon monoxide and hydrogen.

[0089] The gas-gas reaction is mainly:

[0090]

[0091] The gas-gas reaction is mainly a water-gas shift reaction as shown in formula (3). This reaction is a reversible reaction and is affected by the concentrations of carbon monoxide and water vapor, as well as carbon dioxide and hydrogen, in the gas flow channel and the gasification cavity. Excess water vapor can be generated by injecting excess liquid water, causing carbon monoxide and water vapor to react to generate carbon dioxide and hydrogen, keeping the reaction formula (3) continuously moving in the positive direction. In addition, gas-gas reactions are easier to occur than gas-solid reactions. Based on the above reaction characteristics, synthesis gas with different hydrogen and carbon monoxide ratios can be produced by regulating the ratio of carbon dioxide and liquid water injected into the plasma generator through multiple media.

[0092] The plasma generator 29 includes a plasma generator body, a cathode assembly 3, an anode assembly 4, and a reaction medium injection assembly 2. The multi-media injection plasma generator can inject carbon dioxide and liquid water, or hydrogen and liquid water, into the reaction medium injection assembly 2. The gaseous reaction medium atomizes the liquid water and diffuses it between the cathode and anode. Under the action of high-voltage ionization, high-temperature and highly active active particles are generated. The active particles of different compositions react with the coal seam in a series of reactions to produce synthesis gas with different hydrogen-to-carbon ratios.

[0093] The plasma generator body shell is made of steel, copper, alloy or other composite materials, and has high temperature resistance and corrosion resistance. According to the coalbed gasification process design, the plasma generator body 1 can have a diameter of 5 to 10 cm and a length of 60 to 200 cm;

[0094] The reaction medium injection assembly 2 includes a gaseous reaction medium chamber 5, a medium outlet 6, a liquid medium chamber 7, a liquid medium capillary 8, a gaseous reaction medium injection port 9, a liquid medium injection port 10, and an atomizing plate 11. The gaseous reaction medium chamber 5 gradually tapers from the injection end to the outlet end, forming a bell-shaped structure. The injection end of the gaseous reaction medium chamber 5 is located on the left side of the plasma generator body 1, and the outlet end is flush with the left side of the cathode head 13. The gaseous reaction medium gradually increases in pressure as its volume decreases within the gaseous reaction medium chamber 5. However, at the medium outlet 6, its volume increases sharply, and the gas pressure decreases, thereby generating a pressure difference, which can discharge the liquid in the liquid medium chamber 7 through the liquid medium capillary 8 to the medium outlet 6. The liquid medium chamber 7 is located between the gaseous reaction medium chamber 5 and the outer annulus of the anode, forming a roughly right-angled triangle shape with the gaseous reaction medium chamber 5. The liquid medium capillary 8 is provided on one side of the gaseous reaction medium chamber 5, and two or more liquid medium capillaries 8 are evenly distributed along the gaseous reaction medium chamber 5. A baffle is provided between the left side of the liquid medium chamber 7 and the liquid medium injection port 10 to prevent liquid backflow. The gaseous reaction medium injection port 9 is evenly arranged in two or more groups with the cathode rod 12 as the symmetry axis, and is located on the left side of the gaseous reaction medium chamber 5, for evenly inputting the gaseous reaction medium into the gaseous reaction medium chamber 5. The liquid medium injection port 10 is located on the upper and lower sides of the reaction medium injection assembly 2 and is connected to the liquid medium chamber 7. The atomizing plate 11 is fixed on the cathode rod 12, located between the end of the cathode rod 12 and the cathode head 13, and is arranged at the medium outlet 6, for cooperating with the gaseous reaction medium to atomize the liquid water medium. The gaseous reaction medium is injected from the gaseous reaction medium injection port 9, and is continuously pressurized in the gaseous reaction medium chamber 5 before being discharged from the medium outlet 6, where the pressure drops suddenly, forming a pressure difference zone. After the liquid medium is injected from the liquid medium injection port 10, it is affected by the pressure difference and discharged toward the medium outlet 6 along the liquid medium capillary 8. The gaseous reaction medium discharged to the medium outlet 6 is blocked and reflected by the atomizing plate 11 and the anode head 17, cutting the discharged liquid medium, causing the liquid medium to form atomized small droplets, which then diffuse to between the cathode and the anode along with the gaseous reaction medium.

[0095] The cathode assembly 3 includes a cathode rod 12, a cathode head 13, a cathode terminal 14, a cathode coolant injection pipe 15, and a cathode coolant return pipe 16. The cathode rod 12 mainly functions to conduct electricity and cool the cathode head 13. One end of the cathode rod 12 is connected to the cathode terminal 14, and the other end is connected to the cathode head 13. The cathode rod 12 is configured as a hollow tube. The coolant is injected into the cathode coolant injection pipe 15, so that the interior of the cathode component is filled with coolant to cool the cathode head 13. The coolant after heat exchange flows back through the cathode coolant return pipe 16 to achieve coolant circulation injection. The cathode head 13 is configured as a hollow metal part. The outer side is connected to the cathode rod 12 by a thread. The cathode coolant injection pipe 15 extends into the interior of the cathode head 13 to ensure the cooling effect of the cathode head 13.

[0096] The anode assembly 4 includes a cathode head 13, an anode coolant injection pipe 19, an anode terminal 18, an anode coolant injection pipe 19 and an anode coolant return pipe 20. The anode head 17 is located at the right end of the plasma generator body 1 and is connected by threads or bolts. An annulus is set on the outside of the anode head 17, one side of which extends into the anode coolant injection pipe 19, close to the end of the anode head 17, and an outlet is set on the other side as the anode coolant return pipe 20. The coolant enters the annulus through the anode coolant injection pipe 19 to cool and protect the anode head 17. The coolant after heat exchange is returned through the anode coolant return pipe 20 to realize coolant circulation injection. Discharge occurs between the anode head 17 and the cathode head 13, ionizing the gaseous reaction medium and atomized droplets to produce high-temperature and high-activity plasma.

[0097] In one embodiment, the coal seam plasma gasification system includes a conversion channel 22, a reaction assembly 25, and a recovery assembly 26. After vertically passing through the overburden 23 and the upper edge of the coal seam from the ground, it gradually deflects horizontally, forming a non-vertical channel within the coal seam. The non-vertical channel extends a certain distance within the coal seam, and on the other side, the ground passes vertically through the overburden 23 and the coal seam and connects to the non-vertical channel, thus forming a conversion channel 22. The reaction assembly 25 includes a reaction tube 27, an injection tube 28, a plasma generator 29, a reaction tube drive device 30, a gaseous reaction medium injection device, and a liquid medium injection device 32. The reaction tube 27 is within the conversion channel 22 and extends from the ground into the coal seam. One end of the reaction tube 27 is connected to the reaction tube drive device 30 and the injection device at the ground, and the other end is connected to the plasma generator 29 at the ground and lowered into the coal seam 21. The injection pipe 28 is located inside the reaction tube 27 and is coaxial with the injection pipe 28. The injection pipe 28 encloses the reaction medium injection pipe, cooling medium injection pipe, and power cable required by the plasma generator 29. The injection pipe 28 is connected to the reaction tube drive device 30 and the injection device, as well as the plasma generator 29. The reaction tube drive device 30 is connected to one end of the reaction tube 27 and can be used to precisely move the reaction tube 27, including forward and backward movements, with a movement distance accurate to 0.1m. The injection device is connected to the reaction tube drive device 30 and communicates with the injection pipe 28 inside the reaction tube 27. The injection device is provided with multiple reaction medium injection ports, cooling medium injection ports, power cables, and corresponding valves, switches, etc. Each medium valve and each power switch is manually or automatically adjusted. The injection device is used to accurately control the injection amount of gaseous and liquid reaction media, allocate reaction medium injection components, control the flow rate of the cooling medium inlet circuit, and control the start, shutdown, and power of the plasma generator 29.

[0098] The recovery assembly 26 includes a recovery pipe 33, a comprehensive testing device 34, and a flow testing device 35. The recovery pipe 33 is connected to the conversion channel 22, and the surface portion of the recovery pipe 33 is provided with the comprehensive testing device 34 and the flow testing device 35. The comprehensive testing device 34 is arranged on the surface portion of the recovery pipe 33 and is used to test parameters such as the composition, temperature, and pressure of the recovered coal gas. The comprehensive testing device 34 can be used to provide feedback on underground reaction conditions, providing a basis for regulating the coalbed gasification reaction. The flow testing device is arranged on the surface portion of the recovery pipe 33 and is used to test the recovered coal gas flow rate to provide feedback on underground coal seam reaction conditions, determine the coal seam reaction conditions, and provide a basis for moving the reaction pipe 27. According to the construction and installation method, after the conversion channel 22 is machined and all components are installed, the plasma generator 29 is debugged on the surface to test the circulation of the reaction medium and the cooling medium. The power is turned on to test the startup and the reaction medium flow and power adjustment to ensure normal operation. The plasma generator 29 is lowered into the conversion channel 22 via the reaction tube drive device 30 and extended into the coal seam, reaching a horizontal distance of 5 to 50 meters from the recovery pipe 33. The gaseous and liquid medium injection devices 32 control the gaseous and liquid medium injection rates, activate the plasma generator 29, and initiate the coal seam gasification reaction. The gaseous and liquid medium injection rates are regulated based on the outlet gas composition feedback from the comprehensive testing device 34, and the outlet gas flow rate is controlled based on the outlet gas flow rate feedback from the flow testing device 35 to control the movement of the reaction tube 27.

[0099] In one embodiment, the installation and specific conversion process of the plasma generator for the coal seam plasma gasification system are as follows:

[0100] 1) Installation

[0101] After vertically passing through the cover layer 23 and the upper edge of the coal seam 21 from the ground 24, it gradually deflects to the horizontal direction, forming a non-vertical channel in the coal seam. The non-vertical channel extends a certain distance in the coal seam, and on the other side, the ground vertically passes through the cover layer 23 and the coal seam and is connected to the non-vertical channel, thus forming a conversion channel 22 unit.

[0102] A reaction tube 27 extends from the surface into the coal seam within the conversion channel 22. One end of the reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface before being lowered into the coal seam. An injection pipe 28 is located within the reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by the plasma generator 29. The injection pipe 28 connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively.

[0103] Reaction tube 27 extends from the surface into the coal seam within conversion channel 22. One end of reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface and lowered into the coal seam. An injection pipe 28 is located within reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by plasma generator 29. The injection pipe 28, along with the reaction tube 27, connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively. The reaction tube drive unit 30 is connected to one end of reaction tube 27, while the injection unit is connected to the reaction tube drive unit 30 and communicates with the injection pipe 28 within the reaction tube 27. The injection unit is equipped with multiple reaction medium injection ports, cooling medium injection ports, power cables, and corresponding valves and switches.

[0104] Recovery pipe 33 is located within conversion channel 22. One end of recovery pipe 33 is connected to the recovery device and the recovery pipe 33 drive unit on the surface, while the other end extends into the coal seam. A comprehensive testing device 34 and a flow rate testing device 35 are located on the surface portion of recovery pipe 33 and connected to the surface outlet of recovery pipe 33. Recovery pipe 33 is equipped with one to three outlet valves, which can be adjusted manually or automatically.

[0105] After the conversion channel 22 was machined and all components installed according to the construction and installation methods, the plasma generator 29 was debugged on the surface, and its reaction medium and cooling medium circulation were tested. The power was turned on to test startup and the reaction medium flow and power adjustment for normal operation. The plasma generator 29 was lowered into the conversion channel 22 via the reaction tube drive device 30 and extended into the coal seam, reaching a horizontal distance of 5 to 50 meters from the recovery pipe 33.

[0106] 2) Initiation of conversion reaction

[0107] A certain amount of carbon dioxide is injected via the gaseous medium injection device 31, activating the plasma generator 29. Based on feedback from the integrated testing device 34 regarding the outlet gas composition, when the volume percentage of carbon monoxide in the outlet gas exceeds 5%, coal seam gasification has begun. The gaseous medium injection device 31 and the liquid medium injection device 32 control the gaseous medium and liquid medium injection rates, respectively, gradually adjusting the gaseous medium and liquid medium injection rates and the power of the plasma generator 29 to maintain a load between 10% and 50%, and coal seam gasification production begins.

[0108] 3) Main operations of gas composition control

[0109] The multi-media injection plasma generator simultaneously inputs different flow rates of carbon dioxide and liquid water to produce high-temperature and highly active particles in different proportions. It can further control the gas-solid reaction and gas-gas reaction occurring in the coal seam to convert them into hydrogen and carbon monoxide gases in different proportions, directly producing coal gas that meets the synthesis needs of coal-based high-value products.

[0110] The gas-solid reaction is mainly:

[0111] C + H2O = CO + H2 (1)

[0112] C + CO2 = 2CO (2)

[0113] That is, the carbon elements in the coal seam react with high-temperature and highly active water vapor and carbon dioxide particles to form a gas-solid reaction, mainly converting into carbon monoxide and hydrogen.

[0114] The gas-gas reaction is mainly:

[0115]

[0116] The gas-gas reaction is mainly a water-gas shift reaction as shown in formula (3). This reaction is a reversible reaction and is affected by the concentrations of carbon monoxide and water vapor, as well as carbon dioxide and hydrogen, in the gas flow channel and the gasification cavity. Excess water vapor can be generated by injecting excess liquid water, causing carbon monoxide and water vapor to react to generate carbon dioxide and hydrogen, keeping the reaction formula (3) continuously moving in the positive direction. In addition, gas-gas reactions are easier to occur than gas-solid reactions. Based on the above reaction characteristics, synthesis gas with different hydrogen and carbon monoxide ratios can be produced by regulating the ratio of carbon dioxide and liquid water injected into the plasma generator through multiple media.

[0117] Taking the target synthetic product as methane or methanol as an example, the production process generally requires a hydrogen-to-carbon ratio (volume of hydrogen and carbon monoxide) of about 3. According to production requirements, the molar ratio of carbon dioxide and liquid water injected by the plasma generator 29 needs to be regulated. The carbon dioxide injection flow rate is controlled by the gas medium injection device 31, and the liquid medium injection device 32 controls the liquid water injection flow rate so that the molar ratio of injected liquid water and carbon dioxide is about 3. At this time, the gas components produced mainly include hydrogen, carbon monoxide and carbon dioxide, and their volume ratio is about 3:1:2. After the gas is discharged to the ground, it is separated to obtain a synthesis gas with a hydrogen-to-carbon ratio of about 3. The separated carbon dioxide is injected into the plasma generator 29 as a gasifying agent and continues to participate in the reaction. During the production process, the outlet gas composition is fed back by the comprehensive testing device 34 to determine whether the hydrogen-to-carbon ratio is about 3. A hydrogen-to-carbon ratio of 2.8 to 3.2 is a stable production process. If the hydrogen-to-carbon ratio is lower than 2.8, the molar ratio of liquid water and carbon dioxide can be slowly increased until the integrated test device 34 indicates a hydrogen-to-carbon ratio close to 3. If the ratio is higher than 3.2, the molar ratio of liquid water and carbon dioxide can be slightly and slowly decreased until the integrated test device 34 indicates a hydrogen-to-carbon ratio close to 3. When the hydrogen-to-carbon ratio of the outlet gas stabilizes at approximately 3, the molar ratio of liquid water and carbon dioxide is maintained constant, and the liquid water and carbon dioxide injection rates and the power of the plasma generator 29 are slowly adjusted to stabilize the production load at approximately 60%, allowing for stable coalbed gasification. If, after a period of normal production, the outlet gas flow rate continues to decrease as reported by the flow test device 35, this indicates that the coalbed conversion reaction intensity is decreasing as the reaction cavity expands, necessitating an increase in the reaction medium injection rate and the power of the plasma generator 29 to raise the conversion reaction load to 60%-100% and continue production. After a period of time, if the flow rate reported by the flow test device 35 further decreases, this indicates that the coalbed gasification process between the plasma generator 29 and the recovery pipe 33 has completed. Keep the plasma generator 29 started, and move the reaction tube 27 back 50 meters. After the reaction tube 27 is completely retracted, continue the coal seam conversion production.

[0118] Taking the Fischer-Tropsch synthesis of a certain wax as an example, the production process generally requires a hydrogen-to-carbon ratio of approximately 1.4 to 1.8. The gaseous medium injection device 31 and the liquid medium injection device 32 are controlled to maintain a molar ratio of liquid water to carbon dioxide of approximately 5:3. The resulting gas primarily consists of hydrogen, carbon monoxide, and carbon dioxide, with a volume ratio of approximately 5:3:4. After the gas is discharged to the surface, it is separated to produce synthesis gas with a hydrogen-to-carbon ratio of approximately 5:3. The separated carbon dioxide is then injected into the plasma generator 29 as a gasifying agent to continue the reaction. Based on the output gas composition feedback from the comprehensive testing device 34, the hydrogen-to-carbon ratio is determined to be approximately 1.7. A hydrogen-to-carbon ratio of 1.4 to 1.8 indicates a stable production process. If the hydrogen-to-carbon ratio is lower than 1.4, the liquid water-to-carbon dioxide molar ratio can be slowly increased until the comprehensive testing device 34 indicates a hydrogen-to-carbon ratio close to 1.7. If the hydrogen-to-carbon ratio is higher than 1.8, the liquid water-to-carbon dioxide molar ratio can be slightly and slowly reduced until the comprehensive testing device 34 indicates a hydrogen-to-carbon ratio close to 1.7. When the outlet gas hydrogen-to-carbon ratio stabilizes at approximately 1.7, maintain the liquid water / CO2 molar ratio unchanged and slowly adjust the liquid water and CO2 injection rates, as well as the power of the plasma generator 29, until the production load stabilizes at approximately 10% to 50%, thereby stabilizing the coalbed gasification reaction. If, after a period of normal production, the outlet gas flow rate continues to decrease as reported by the flow meter 35, this indicates that the coalbed conversion reaction intensity is decreasing as the reaction cavity expands, increasing the reaction medium injection rate and the power of the plasma generator 29 to raise the conversion reaction load to 60% to 100% and continuing production. After a period of time, if the flow rate reported by the flow meter 35 further decreases, this indicates that the coalbed gasification process between the plasma generator 29 and the recovery pipe 33 is complete. Keep the plasma generator 29 activated and withdraw the mobile reaction tube 27 by 50 meters. Once the reaction tube 27 is fully withdrawn, coalbed conversion production can resume.

[0119] 4) Production end operation

[0120] Production is adjusted in this cycle. When the movement distance of the reaction tube drive unit 30 approaches the non-vertical distance of the conversion channel 22, conversion of the overlying coal seam in that unit is complete. The plasma generator 29 is powered off, reaction medium injection is stopped, while cooling medium injection is maintained. The reaction tube 27 and recovery pipe 33 are then withdrawn to the surface. This well shut-in operation is then performed. Following the above method, construction, installation, and gasification production are carried out in another target coal seam block.

[0121] Example 1: (Coalbed gasification to produce methanol)

[0122] The present invention proposes a method for producing methanol from coal seam gasification. The coal seam is buried at a depth of about 1020m, with an average thickness of 8m. The coal is anthracite. A conversion unit is designed to cover a horizontal distance of 1000m from the coal seam. The target product synthesized on the ground is methanol.

[0123] After passing through the overburden 23 and the upper edge of the coal seam vertically from the ground, it gradually deflects horizontally to form a non-vertical channel in the coal seam. The non-vertical channel extends 1000m in the coal seam, and on the other side, the ground passes through the overburden 23 and the coal seam vertically and connects with the non-vertical channel, thus forming a conversion channel 22.

[0124] A reaction tube 27 extends from the surface into the coal seam within the conversion channel 22. One end of the reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface before being lowered into the coal seam. An injection pipe 28 is located within the reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by the plasma generator 29. The injection pipe 28 connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively.

[0125] Reaction tube 27 extends from the surface into the coal seam within conversion channel 22. One end of reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface and lowered into the coal seam. An injection pipe 28 is located within reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by plasma generator 29. The injection pipe 28, along with the reaction tube 27, connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively. The reaction tube drive unit 30 is connected to one end of reaction tube 27, while the injection unit is connected to the reaction tube drive unit 30 and communicates with the injection pipe 28 within the reaction tube 27. The injection unit is equipped with multiple reaction medium injection ports, cooling medium injection ports, power cables, and corresponding valves and switches.

[0126] The recovery pipe 33 is located within the conversion channel 22. One end of the recovery pipe 33 is connected to the recovery device and the recovery pipe 33 drive unit on the surface, while the other end extends into the coal seam. A comprehensive testing device 34 and a flow rate testing device 35 are located on the surface portion of the recovery pipe 33 and connected to the surface outlet of the recovery pipe 33. The recovery pipe 33 is equipped with an outlet valve that can be adjusted manually or automatically.

[0127] After the conversion channel 22 was machined and all components installed according to the construction and installation methods, the plasma generator 29 was debugged on the surface, and its reaction medium and cooling medium circulation were tested. The power was turned on to test the startup and reaction medium flow and power adjustment. The plasma generator 29 was lowered into the conversion channel 22 via the reaction tube drive device 30 and extended into the coal seam, reaching a horizontal distance of 20 meters from the recovery pipe 33.

[0128] 100 Nm is injected by the gas medium injection device 31 3 / h carbon dioxide, start the plasma generator 29. According to the feedback of the outlet gas composition by the comprehensive testing device 34, when the volume percentage of carbon monoxide in the outlet gas is higher than 5%, it indicates that the coal seam has started gasification reaction. The gas medium injection device 31 adjusts the carbon dioxide flow rate to 200Nm 3 / h, the liquid water injection flow rate of the liquid medium injection device 32 is about 480kg / h, the power of the plasma generator 29 is adjusted to about 1000kW, and the load of the plasma generator 29 is maintained between 10% and 50%. According to the feedback of the outlet gas composition from the comprehensive testing device 34, the hydrogen-carbon ratio is stabilized between 2.8 and 3.2, and the molar ratio of liquid water and carbon dioxide is kept unchanged. The injection flow rates of liquid water and carbon dioxide and the power of the plasma generator 29 are slowly adjusted to stabilize the production load at about 10% to 50%, and the coalbed gasification reaction begins to stabilize.

[0129] After 10 days of continuous production, the integrated testing device 34 reported that the hydrogen-carbon ratio of the outlet coal gas was higher than 3.2, which may be due to the high water content of the coal seam. The molar ratio of liquid water and carbon dioxide was slowly reduced through the injection device until the integrated testing device 34 showed that the hydrogen-carbon ratio was close to 3.

[0130] After 15 days of normal production, the flow test device 35 reported that the outlet gas flow rate continued to decline, indicating that the coal seam conversion reaction intensity decreased with the increase of the reaction cavity. The molar ratio of liquid water and carbon dioxide was kept unchanged, and the carbon dioxide injection flow rate was increased to 400Nm 3 / h, the liquid water injection flow rate is about 960kg / h, and the power of the plasma generator 29 is about 2000kW, so that the conversion reaction load is increased to 60% to 100%, and production continues.

[0131] Six days later, flow rate measurement device 35 reported a further decrease in flow rate, indicating that the coal seam between plasma generator 29 and recovery pipe 33 had been completely converted. Plasma generator 29 was kept active, and the mobile reaction tube 27 was withdrawn by 2720 m. After the reaction tube 27 was completely withdrawn, coal seam conversion production continued.

[0132] Following this cycle of production adjustments, the movement distance of the reaction tube drive unit 30 approached 1000 meters, indicating that the overlying coal seam in this unit had been fully converted. The plasma generator 29 was powered off, and the injection of the reaction medium ceased, while the injection of the cooling medium was maintained. The reaction tube 27 and the recovery tube 33 were then withdrawn to the surface. This shut-in operation was then carried out. Following the above method, construction, installation, and gasification production were carried out in another target coal seam block.

[0133] Example 2: (Coalbed gasification combined with Fischer-Tropsch synthesis to produce wax products)

[0134] The present invention proposes a method for producing wax products by combining coalbed gasification with Fischer-Tropsch synthesis. The coal seam is approximately 1,260 meters deep, with an average thickness of 9 meters. The coal is lignite. A conversion unit is designed to cover a horizontal distance of 1,500 meters from the coal seam. The target product of the surface synthesis is wax products.

[0135] After passing through the overburden 23 and the upper edge of the coal seam vertically from the ground, it gradually deflects horizontally, forming a non-vertical channel in the coal seam. The non-vertical channel extends 1500m in the coal seam, and on the other side, the ground passes through the overburden 23 and the coal seam vertically and connects with the non-vertical channel, thus forming a conversion channel 22.

[0136] A reaction tube 27 extends from the surface into the coal seam within the conversion channel 22. One end of the reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface before being lowered into the coal seam. An injection pipe 28 is located within the reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by the plasma generator 29. The injection pipe 28 connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively.

[0137] Reaction tube 27 extends from the surface into the coal seam within conversion channel 22. One end of reaction tube 27 is connected to a reaction tube drive unit 30 and an injection unit at the surface, while the other end is connected to a plasma generator 29 at the surface and lowered into the coal seam. An injection pipe 28 is located within reaction tube 27 and is coaxial with the injection pipe 28. This pipe houses the reaction medium injection pipe, cooling medium injection pipe, and power cables required by plasma generator 29. The injection pipe 28, along with the reaction tube 27, connects to the reaction tube drive unit 30, the injection unit, and the plasma generator 29, respectively. The reaction tube drive unit 30 is connected to one end of reaction tube 27, while the injection unit is connected to the reaction tube drive unit 30 and communicates with the injection pipe 28 within the reaction tube 27. The injection unit is equipped with multiple reaction medium injection ports, cooling medium injection ports, power cables, and corresponding valves and switches.

[0138] The recovery pipe 33 is located within the conversion channel 22. One end of the recovery pipe 33 is connected to the recovery device and the recovery pipe 33 drive unit on the surface, while the other end extends into the coal seam. A comprehensive testing device 34 and a flow rate testing device 35 are located on the surface portion of the recovery pipe 33 and connected to the surface outlet of the recovery pipe 33. The recovery pipe 33 is equipped with two outlet valves, which can be adjusted manually or automatically.

[0139] After the conversion channel 22 was machined and all components installed according to the construction and installation methods, the plasma generator 29 was tested on the surface, with the flow of reaction medium and cooling medium tested. The power was turned on to verify startup, reaction medium flow rate, and power adjustment. The plasma generator 29 was lowered into the conversion channel 22 via the reaction tube drive device 30 and extended into the coal seam, reaching a horizontal distance of 50 meters from the recovery pipe 33.

[0140] 100 Nm is injected by the gas medium injection device 31 3 / h carbon dioxide, start the plasma generator 29. According to the feedback of the outlet gas composition by the comprehensive testing device 34, when the volume percentage of carbon monoxide in the outlet gas is higher than 5%, it indicates that the coal seam has started gasification reaction. The gas medium injection device 31 adjusts the carbon dioxide flow rate to 200Nm 3 / h, the liquid water injection flow rate of the liquid medium injection device 32 is about 480kg / h, the power of the plasma generator 29 is adjusted to about 1000kW, and the load of the plasma generator 29 is maintained between 10% and 50%. According to the feedback of the outlet gas composition from the comprehensive testing device 34, the hydrogen-carbon ratio is stabilized between 1.4 and 1.8, and the molar ratio of liquid water and carbon dioxide is kept unchanged. The injection flow rates of liquid water and carbon dioxide and the power of the plasma generator 29 are slowly adjusted to stabilize the production load at about 10% to 50%, and the coalbed gasification reaction begins to stabilize.

[0141] After 6 days of continuous production, the integrated testing device 34 reported that the hydrogen-carbon ratio of the outlet gas was lower than 1.4. The molar ratio of liquid water and carbon dioxide was slowly increased through the injection device until the integrated testing device 34 showed that the hydrogen-carbon ratio was close to 1.7.

[0142] After 17 days of normal production, the flow test device 35 reported that the outlet gas flow rate continued to decline, indicating that the coal seam conversion reaction intensity decreased with the increase of the reaction cavity. The molar ratio of liquid water and carbon dioxide was kept unchanged, and the carbon dioxide injection flow rate was increased to 400Nm 3 / h, the liquid water injection flow rate is about 960kg / h, and the power of the plasma generator 29 is about 2000kW, so that the conversion reaction load is increased to 60% to 100%, and production continues.

[0143] After seven days, flow rate measurement device 35 reported a further decrease in flow rate, indicating that the coal seam between plasma generator 29 and recovery pipe 33 had been completely converted. Plasma generator 29 was kept activated, and the mobile reaction tube 27 was withdrawn 2750 m. After the reaction tube 27 was completely withdrawn, coal seam conversion production continued.

[0144] Following this cycle of production adjustments, the movement distance of the reaction tube drive unit 30 reached approximately 1500 meters, indicating that the overlying coal seam in this unit had been fully converted. The plasma generator 29 was powered off, and the injection of the reaction medium ceased, while the injection of the cooling medium was maintained. The reaction tube 27 and the recovery tube 33 were then withdrawn to the surface. This shut-in operation was then carried out. Following the above method, construction, installation, and gasification production were carried out in another target coal seam block.

[0145] Finally, it should be noted that the described embodiments are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of this application.

[0146] The above description is merely illustrative of certain exemplary embodiments of the present invention. It goes without saying that those skilled in the art will be able to modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and description are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A plasma generator for a coal seam plasma gasification system, characterized in that: include: Plasma generator body; The cathode assembly is arranged in the plasma generator body, and the cathode assembly includes: The cathode head is a hollow metal part. The cathode rod is a hollow tube that conducts electricity and cools the cathode head. One end of the cathode rod is connected to the cathode terminal, and the other end is threadedly connected to the cathode head. The cathode coolant injection pipe passes through the cathode rod and goes deep into the cathode head so that the cathode head is filled with coolant to reduce the temperature. A cathode coolant return pipe is connected to the cathode rod so that the coolant after heat exchange can flow back through the cathode coolant return pipe to achieve coolant circulation injection; A reaction medium injection assembly is provided in the plasma generator body and is used for injecting the reaction medium; The anode assembly is arranged in the plasma generator body and is used to cooperate with the cathode assembly to start an arc after being energized to transform the reaction medium.

2. The plasma generator for coal seam plasma gasification system according to claim 1, characterized in that: The reaction medium injection assembly comprises: a gaseous reaction medium chamber comprising an injection end located on the left side of the plasma generator body and an outlet end flush with the left side of the cathode head; the gaseous reaction medium chamber gradually narrows from the injection end toward the outlet end and has a bell-mouth shape, so that the pressure of the gaseous reaction medium in the gaseous reaction medium chamber gradually increases due to the gradual reduction in volume; and a gaseous reaction medium injection port is provided at the injection end; The medium outlet is connected to the outlet end and causes the volume of the gaseous reaction medium from the gaseous reaction medium chamber to increase sharply and the gas pressure to decrease so as to generate a pressure difference.

3. The plasma generator for coal seam plasma gasification system according to claim 2, characterized in that: The reaction medium injection assembly further comprises: The liquid medium cavity is located between the gaseous reaction medium cavity and the outer annulus of the anode, and is in the shape of a right triangle with the gaseous reaction medium cavity. The liquid medium cavity is provided with at least one liquid medium capillary on one side of the gaseous reaction medium cavity; A liquid medium injection port for injecting liquid medium is provided on the left side of the liquid medium cavity. The liquid medium injection port is located on the upper and lower sides of the reaction medium injection assembly and is connected to the liquid medium cavity. The liquid medium from the liquid medium capillary is discharged from the medium outlet via the pressure difference.

4. The plasma generator for coal seam plasma gasification system according to claim 2, characterized in that: The reaction medium injection assembly also includes: an atomizing plate, which is fixed on the cathode rod and arranged at the medium outlet to work together with the gaseous reaction medium to atomize the liquid medium to form atomized droplets, and the atomized droplets diffuse between the cathode and the anode with the gaseous reaction medium.

5. The plasma generator for coal seam plasma gasification system according to claim 2, characterized in that: The anode assembly comprises: The anode head is connected to the right end of the plasma generator body through threads or bolts, and an annulus is set outside the anode head. The anode terminal is electrically connected to the anode head, and discharge between the anode head and the cathode head ionizes the gaseous reaction medium and the atomized droplets to generate high-temperature and high-activity plasma. an anode coolant injection pipe, which is connected to one side of the annulus to introduce coolant into the annulus to cool the anode head; The anode coolant return pipe is connected to the other side of the annulus to reflux the coolant after heat exchange, thereby realizing coolant circulation injection.

6. The plasma generator for coal seam plasma gasification system according to claim 2, characterized in that: The gaseous reaction medium injection ports are evenly arranged in two or more groups with the cathode rod as the symmetry axis and are located on the left side of the gaseous reaction medium cavity for evenly inputting the gaseous reaction medium into the gaseous reaction medium cavity.

7. The plasma generator for coal seam plasma gasification system according to claim 3, characterized in that: Two or more capillaries from the liquid medium are evenly distributed along the gaseous reaction medium cavity, and a baffle for preventing liquid backflow is provided between the left side of the liquid medium cavity and the liquid medium injection port.

8. The plasma generator for coal seam plasma gasification system according to claim 3, characterized in that: The cathode coolant injection pipe, cathode coolant return pipe, anode coolant injection pipe and anode coolant return pipe are connected to the cooling medium injection port, and the gaseous reaction medium injection port and liquid medium injection port are respectively connected to the reaction medium injection port.

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