CN114231322A

CN114231322A - Gas purification and carbon dioxide circulation treatment method

Info

Publication number: CN114231322A
Application number: CN202111674609.3A
Authority: CN
Inventors: 李东奇; 付燕
Original assignee: Beijing Paichuang Petroleum Technology Service Co ltd
Current assignee: Beijing Paichuang Petroleum Technology Service Co ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-03-25
Anticipated expiration: 2041-12-31
Also published as: CN114231322B

Abstract

The invention provides a coal gas purification and carbon dioxide circulation treatment method, which comprises the following steps: determining the stratum depth and the stratum inclination angle of the coal layer, drilling a gas injection well, a gas production well and a directional well, injecting gas into the directional well through the gas injection well, igniting a combustion cavity, and sequentially introducing the gas into a heat exchanger and a cooling tower through the gas production well for heat exchange; then the carbon dioxide enters a desulfurizing tower for desulfurization treatment to form a sulfate solution, and part of the carbon dioxide is absorbed simultaneously to form a mixed solution of a carbonate solution and a sulfate; the coal gas enters a decarbonizing tower to convert carbon dioxide in the coal gas into alcohol amine solution rich liquid; and conveying the alcohol amine solution rich liquid to a stripping tower, and decomposing the alcohol amine solution rich liquid in the stripping tower through a catalyst to produce carbon dioxide gas. The technical scheme of the application has effectively solved the problem that the direct emission of carbon dioxide in the coal gas in the correlation technique and then can increase the pollution of environment.

Description

Gas purification and carbon dioxide circulation treatment method

Technical Field

The invention relates to the technical field of gas purification, in particular to a gas purification and carbon dioxide circulation treatment method.

Background

The principle of coal gasification refers to that coal in a specific environment leads organic matters in the coal to be mixed with injected gasification agent (oxygen/nitrogen)Carbon dioxide gas, water vapor and the like, and low-temperature gas and high-temperature gas) under the action of certain pressure and temperature, coal is combusted to generate high temperature, the high temperature and the water vapor are subjected to chemical reaction to generate a series of chemical reaction processes of decomposing to generate gas, and solid coal is converted into gas containing CO and H₂、CH₄Isocombustible gas and CO₂N2, etc. When coal is gasified, three conditions, namely a gasification furnace, an oxidant and steam, are required, and one of the three conditions is not necessary. The reactions that occur in the gasification process include pyrolysis, gasification, and combustion reactions of coal. Pyrolysis of coal refers to the decomposition process of coal from solid phase to gas, solid, liquid three-phase products.

Coal gasification is divided into ground gasification and underground in-situ gasification, the ground gasification is carried out in a controllable gasification furnace produced by a manufacturing factory, the coal is subjected to constant pressure gasification control in the gasification furnace to obtain stable coal gas components, the coal gasification equipment is ideal coal gasification equipment, the underground gasification furnace is an original geological coal bed gasification furnace formed by drilling under a natural geological state, because the coal bed is influenced by extrusion of upper and lower strata and immersion of underground water under the action of natural geological characteristics, pressure control in a gasification channel, external force immersion in the stratum under the action of stratum pressure and leakage under the action of coal gas pressure are two aspects of positive pressure and back pressure, the change or unbalance of the pressure can cause the change of the gasification state, thereby influencing the change of effective coal gas components, and moreover, different lamination pressures of different coal bed depths can be different, an original technical method and special equipment are needed to control the influence of the multi-flow state of the coal bed in the underground coal gasification on the gasification furnace chamber, the underground coal gasification furnace is regarded as a controllable simulated ground gasification furnace, so that the regulation and control of effective components of coal gas in the gasification of multiple flow states during in-situ gasification of underground coal are realized, controllable combustion, controllable gasification, stable pressure and stable yield and pressure maintaining gasification are realized under the condition of high temperature and high pressure of a gasification furnace chamber, the high pressure is determined by natural conditions of geological pressure of a stratum, the high pressure is used for avoiding the immersion of high external pressure of a coal bed stratum on the one hand and ensuring the rapid cooling of mixed coal gas in the coal gas gasification furnace flowing out of the ground on the other hand, thereby reducing the time of oxidizing carbon monoxide into carbon dioxide, but fine coal ash dust particles can be mixed in coal gas flow, and the purity of the coal gas is influenced. And the coal gas contains a large amount of carbon dioxide, the carbon dioxide cannot be combusted, the combustion effect of the coal gas is influenced, and meanwhile, if the carbon dioxide is discharged, the environmental pollution is increased.

Disclosure of Invention

The invention mainly aims to provide a method for purifying coal gas and circularly treating carbon dioxide, so as to solve the problem that the carbon dioxide in the coal gas is directly discharged to increase the environmental pollution in the related technology.

In order to achieve the aim, the invention provides a method for purifying coal gas and circularly treating carbon dioxide, which comprises the following steps: step S10: determining the stratum depth and the stratum inclination angle of a coal layer, drilling a gas injection well and a gas production well at the determined well position of the coal layer, and drilling a directional well in the coal layer so that the directional well is communicated with the gas injection well and the gas production well, forming an interactive well bottom at the joint of the directional well and the gas production well, and forming a combustion cavity at the rear end of the interactive well bottom; step S20: injecting gas into the directional well through the gas injection well to ignite the combustion cavity and generate coal gas; step S30: gas enters a heat exchanger and a cooling tower in sequence through a gas production well to exchange heat; step S40: the coal gas after heat exchange enters a desulfurizing tower for desulfurization treatment to form a sulfate solution, part of carbon dioxide is absorbed simultaneously to form a carbonate solution and a sulfate mixed solution, and then the sulfate and carbonate mixed solution is cached and injected underground; step S50: the desulfurized coal gas enters a decarbonizing tower to convert carbon dioxide in the coal gas into alcohol amine solution rich liquid; step S60: conveying the alcohol amine solution rich solution into a stripping tower, and decomposing the alcohol amine solution rich solution in the stripping tower through a catalyst to produce carbon dioxide gas; wherein, in step S60, the heat obtained by the heat exchange of the coal gas entering the heat exchanger and the cooling tower is transferred to the stripping tower to heat the stripping tower so as to keep the stripping tower at a constant temperature.

Further, step S70 is included after step S60, and step S70: the generated carbon dioxide gas is conveyed into the gas injection well through the RTP pipe and injected into the combustion chamber.

Further, step S80 is included after step S70, and step S80: the carbon dioxide gas is reduced into carbon monoxide and oxygen in the combustion chamber under the action of the nano alumina catalyst and high temperature.

Further, in step S50, the decarbonizing tower includes a spiral spray pipe inside, the alcohol amine solution lean solution is injected into the spray pipe, and the carbonic anhydrase catalyst is sprayed and solidified on the inner wall of the decarbonizing tower and the outer wall of the spray pipe.

Further, in step S60, nano titanium oxide is added to the stripper.

Further, in step S60, the alcohol amine solution rich solution is decomposed to generate an alcohol amine solution lean solution, and the alcohol amine solution lean solution is transported to the decarbonization tower by a pump.

Further, in step S60, the heat obtained by the heat exchange is partially used for cogeneration, and the remaining heat is transferred to the stripper.

Further, in step S40, limestone water is injected into the desulfurization tower so that the limestone water performs desulfurization treatment on the gas.

Further, in step S30, the cooling tower can perform dust removal treatment on the coal gas.

Further, in step S30, the gas is rotated downward in the cooling tower by centrifugal force, moved upward at the conical structure contacting the bottom of the cooling tower, and the solid dust particles in the gas are discharged through the bottom of the cooling tower.

By applying the technical scheme of the invention, the stratum depth and the stratum inclination angle of the coal layer are firstly determined, the well position of the gas injection well and the well position of the gas production well are selected from the determined well position positions of the coal layer, and the well position of the gas injection well and the well position of the gas production well are positioned at two ends of the coal layer, so that the underground combustion cavity is large enough, and the gas production efficiency can be ensured. After determining the well position of the gas injection well and the well position of the gas production well, drilling and completing the well to obtain the gas injection well and the gas production well; and drilling a directional well to communicate the directional well with the gas injection well and the gas production well, reaming a hole at the joint of the gas production well and the directional well to form an interactive well bottom, and pumping back for a certain length to form a combustion chamber to prepare for subsequently igniting coal bed to generate coal gas. Gas is injected into the combustion cavity through the gas injection well so as to ignite the combustion cavity and further generate coal gas. The generated coal gas is high-temperature and high-pressure coal gas, and the coal gas is conveyed into a heat recovery cooling tower through a gas production well, so that heat exchange is carried out to reduce the temperature of the coal gas and effectively utilize the high temperature of the coal gas. The coal gas after heat exchange needs to be subjected to desulfurization treatment, namely the coal gas is conveyed into a desulfurization tower to be subjected to desulfurization treatment, so that the coal gas can be relatively pure. However, the coal gas also contains a large amount of carbon dioxide, which cannot be combusted and is discharged to have a great influence on the environment. Thus, carbon dioxide needs to be recovered. Namely, the coal gas is conveyed into a decarbonizing tower, and carbon dioxide is converted into an alcohol amine solution rich solution in a solvent absorption mode. At the moment, the sulfate solution formed by desulfurization is conveyed to an underground perfusion buffer tank for temporary storage, and the sulfate solution and other harmful wastes are mixed and subjected to slurrying treatment and are perfused into an underground coal seam. And conveying the alcohol amine solution rich solution formed by absorbing carbon dioxide by the solvent to a stripping tower for regeneration, and transferring heat obtained by heat exchange to the stripping tower under the action of a catalyst to heat the stripping tower at a constant temperature, so that the alcohol amine solution rich solution is decomposed to separate out carbon dioxide gas and reduce to obtain an alcohol amine solution lean solution. The carbon dioxide gas is recovered and then injected into the combustion chamber to be converted into carbon monoxide or used for other purposes, thereby realizing zero emission of the carbon dioxide. Therefore, the technical scheme can solve the problem of environmental pollution caused by coal gas purification and direct emission of carbon dioxide, and realize an energy mode of carbon dioxide capture, utilization and conversion. Therefore, the technical scheme of the application effectively solves the problem that the direct emission of carbon dioxide in coal gas in the related art can increase the environmental pollution.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic flow diagram of an embodiment of a gas purification and carbon dioxide recycle treatment process according to the present invention;

FIG. 2 is a schematic diagram showing the heat exchanger, cooling tower, desulfurizing tower, decarbonizing tower and stripping tower of the gas purification and carbon dioxide recycling method of FIG. 1;

FIG. 3 shows a partial enlarged view at A of FIG. 2;

fig. 4 shows a process of forming a gasification and withdrawal combustion chamber of a coal bed, a gas injection well, a gas production well and a directional well of the gas purification and carbon dioxide recycling method of fig. 1.

Wherein the figures include the following reference numerals:

10. a coal layer; 20. a gas injection well; 30. a gas production well; 40. a directional well; 401. a first combustion chamber; 50. a combustion chamber; 60. a cooling tower; 70. a desulfurizing tower; 80. a carbon removal tower; 81. a shower pipe; 90. a stripper column; 100. a heat exchanger.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

The in-situ controllable combustion pressure-maintaining gasification of underground deep coal refers to simulating the gasification state of the underground coal bed into a closed environment of a ground gasification furnace, the underground deep coal is directly gasified in an original geological reservoir, a single-well gasification furnace is formed by a specially designed gasification well group and special equipment matched with the gasification well group, various oxidation catalysts required for gasification are injected into a coal bed through a specially-made gas injection well 20-mouth device, a PLC-controlled high-temperature and high-pressure gas injection boiler, a PLC-controlled high-temperature and high-pressure gas injection manifold and a PLC-controlled specially-made composite continuous gas injection pipe device, a nozzle at the tail end of a continuous pipe in the coal bed is an inlet of the high-temperature and high-pressure oxidation catalyst, the pumping length of the continuous pipe is the addition amount of raw coal of the gasification furnace each time, so that the oxidation catalyst moving in the nozzle is injected into the nozzle like a moving toe, and the coal outside the nozzle is combusted and gasified to form a continuously controllable gasification furnace chamber, the coal gas flow naturally flows to the low-pressure gas production port, the electric control valve on the main path of the gas production measurement and control wellhead device controls the flow of the coal gas flow, an underground coal bed adjustable gasification furnace chamber is formed, and the temperature and pressure regulation of the gasification furnace changes the combustion, gasification and reduction states of the coal gasification furnace. The measurement port is arranged on the measurement and control gas production wellhead device to perform online real-time data acquisition, detection, calculation, analysis, judgment and decision on the synthetic gas flow, so as to realize the adjustment of the states of the gas injection side gasification catalyst and related equipmentControlling to make the underground deep coal layer gasification furnace chamber perform pressure-controllable, pressure-stabilizing and pressure-maintaining gasification under the relatively stable pressure state, thereby ensuring that the synthetic coal gas parameters generated by the gasification of the deep coal are according to the effective coal gas component H required by the design₂+ CO) maximization, gas calorific value maximization, and gas flow yield maximization. And to realize H₂+ CO maximization, coal gas calorific value maximization, and coal gas flow yield maximization. The high-temperature high-pressure gas produced from the gas production wellhead contains a large amount of high-temperature heat energy, fine dust, sulfur-containing gas and carbon dioxide components, and the gas needs to be purified for use and separation and conversion in the subsequent process flow.

As shown in fig. 1, 2 and 4, in the present embodiment, the method for gas purification and carbon dioxide recycling includes: step S10: determining the stratum depth and the stratum inclination angle of the coal layer 10, drilling a gas injection well 20 and a gas production well 30 at the determined well position of the coal layer 10, drilling a directional well 40 in the coal layer 10 to enable the directional well 40 to be communicated with the gas injection well 20 and the gas production well 30, forming an interactive well bottom at the connection position of the directional well 40 and the gas production well 30, and forming a combustion cavity 50 at the rear end of the interactive well bottom; step S20: injecting gas into the directional well 40 through the gas injection well 20 to ignite the combustion chamber 50 and generate gas; step S30: the coal gas enters the heat exchanger 100 and the cooling tower 60 in sequence through the gas production well 30 for heat exchange; step S40: the coal gas after heat exchange enters a desulfurizing tower 70 for desulfurization treatment to form a sulfate solution, part of carbon dioxide is absorbed simultaneously to form a carbonate solution and a sulfate mixed solution, and then the sulfate and carbonate mixed solution is cached and injected underground; step S50: the desulfurized coal gas enters a decarbonizing tower 80 to convert carbon dioxide in the coal gas into alcohol amine solution rich liquid; step S60: conveying the alcohol amine solution rich solution into a stripping tower 90, and decomposing the alcohol amine solution rich solution in the stripping tower 90 through a catalyst to produce carbon dioxide gas; wherein, in step S60, the heat of the gas entering the heat exchanger 100 and the cooling tower 60 is transferred to the stripper 90 to heat the stripper 90, so as to keep the stripper 90 at a constant temperature.

By applying the technical scheme of the embodiment, the formation depth and the formation inclination angle of the coal layer 10 are determined, the well position of the gas injection well 20 and the well position of the gas production well 30 are selected from the determined well position of the coal layer 10, and the well position of the gas injection well 20 and the well position of the gas production well 30 are located at two ends of the coal layer 10, so that the underground combustion cavity 50 is large enough, and the gas production efficiency can be ensured. After the well position of the gas injection well 20 and the well position of the gas production well 30 are determined, drilling and completing to obtain the gas injection well 20 and the gas production well 30; and then drilling a directional well 40 to enable the directional well 40 to be communicated with the gas injection well 20 and the gas production well 30, reaming a hole at the joint of the gas production well 30 and the directional well 40 to form an interactive well bottom, and pumping back for a certain length to form a combustion chamber 50 to prepare for subsequently igniting coal seams to generate coal gas. Gas is injected into the combustion chamber 50 through the gas injection well to ignite the combustion chamber 50 and generate gas. The generated gas is high-temperature and high-pressure gas, and is delivered to the heat recovery cooling tower 60 through the gas production well 30, heat exchange is performed to reduce the temperature of the gas, and the high temperature of the gas is effectively utilized. The heat-exchanged gas needs to be desulfurized, i.e. the gas is sent to the desulfurizing tower 70 for desulfurization, so that the gas is relatively pure. However, the coal gas also contains a large amount of carbon dioxide, which cannot be combusted and is discharged to have a great influence on the environment. Thus, carbon dioxide needs to be recovered. Namely, the coal gas is conveyed into a decarbonizing tower 80, and carbon dioxide is converted into alcohol amine solution rich liquid in a solvent absorption mode. At the moment, the sulfate solution formed by desulfurization is conveyed to an underground perfusion buffer tank for temporary storage, and the sulfate solution and other harmful wastes are mixed and subjected to slurrying treatment and are perfused into an underground coal seam. The rich liquid of the alcohol amine solution formed by absorbing carbon dioxide with the solvent is conveyed to the stripping tower 90 for regeneration, and the heat obtained by heat exchange under the action of the catalyst is transferred to the stripping tower 90 to heat the stripping tower 90 at a constant temperature, so that the rich liquid of the alcohol amine solution is decomposed to separate out carbon dioxide gas and reduce the lean liquid of the alcohol amine solution. The carbon dioxide gas is recovered and then injected into the combustion chamber 50 to be converted into carbon monoxide or used for other purposes, thereby realizing 'zero emission' of carbon dioxide. Therefore, the technical scheme can solve the problem of environmental pollution caused by coal gas purification and direct emission of carbon dioxide, and realize an energy mode of carbon dioxide capture, utilization and conversion. Therefore, the technical scheme of the embodiment effectively solves the problem that the direct emission of carbon dioxide in coal gas in the related art can increase the environmental pollution.

The alcohol amine solution rich solution contains a large amount of carbon dioxide in the alcohol amine solution, and the alcohol amine solution lean solution contains no carbon dioxide or a small amount of carbon dioxide. The alcohol amine solution is alcohol amine MDEA (Methylithanolamine) solution with molecular formula of C₅H₁₃NO₂。

In this embodiment, the method further includes the following steps: and conveying the sulfate solution to an underground perfusion buffer tank for temporary storage, and performing mixed slurrying treatment on the sulfate solution and other harmful wastes to be perfused into an underground coal seam.

As shown in fig. 1, fig. 2 and fig. 4, in the technical solution of the present embodiment, the cooling tower includes a plurality of two types connected in series, the desulfurization tower includes a plurality of desulfurization towers, the decarbonization tower includes a plurality of decarbonization towers, and the plurality of cooling towers are sequentially communicated. The plurality of desulfurizing towers are communicated in sequence, and one desulfurizing tower at the head end of the plurality of desulfurizing towers is communicated with one cooling tower at the tail end of the plurality of cooling towers. And the plurality of decarbonizing towers are sequentially communicated, and one decarbonizing tower at the head end of the plurality of decarbonizing towers is communicated with one desulfurizing tower at the tail end of the plurality of desulfurizing towers. The cooling tower comprises a first shell, an inner cooling pipe, an outer cooling pipe and a first inlet and outlet device, the first inlet and outlet device is arranged above the first shell, the inner cooling pipe is arranged inside the first shell, the outer cooling pipe is arranged outside the first shell, the first inlet and outlet device comprises a volute structure, an air inlet and an air outlet, the air inlet is arranged on the side portion of the volute structure, and the air outlet is arranged at the top of the volute structure. Through foretell setting up in coal gas enters into the spiral case structure through the air inlet earlier, takes place to rotate in the spiral case structure, and then makes coal gas downstream, promptly with interior cooling tube direct contact, and then realized that coal gas heats the heating gradually of heat recovery solution and lowers the temperature to coal gas. Meanwhile, the inner cooling pipe is communicated with the outer cooling pipe, so that the cooling efficiency of the coal gas is higher. Dust in the coal gas can be effectively removed through the cooling tower; while heat exchange is efficiently performed through the inner and outer cooling tubes, such heat exchange obtains a large amount of heat that can be used for subsequent other operations (e.g., power generation). The inner cooling pipe and the outer cooling pipe are both spiral coil pipe structures and are communicated, and the water inlet is located at the end part, close to the bottom of the first shell, of the outer cooling pipe.

As shown in fig. 1, 2 and 4, in the present embodiment, the coal layer 10 is a pulverized coal layer, but may be a conventional coal layer 10. The underground deep coal in-situ pressure-maintaining gasification has no special requirement on the type of coal, and resource blocks suitable for the underground deep coal in-situ pressure-maintaining gasification are selected from the explored unexplored coal resource blocks. Resource reserves are required to be in principle not less than 5 million tons. The factors mainly considered include factors such as coal bed physical property, coal quality components, coal bed depth, stratum inclination angle, coal bed water content, coal bed geological pressure, upper and lower top and bottom plate geological lithology, two-dimensional/three-dimensional seismic data, fault fracture zone, underground water reservoir depth and the like, and the coal gasification resource reserve utilization rate is 75-85%. The underground deep coal gasification preferentially selects an original underground deep coal reservoir with a single-layer coal layer thickness of not less than 5 meters, a coal layer stratum inclination angle of less than 15 degrees, a top plate and a bottom plate which are stably buried for 800-1500 meters, resource blocks with a coal reservoir geological pressure of not more than 7MPa, single-well group gasification furnace groups with a gas injection (steam) well and a measurement and control gas production well 30-well spacing interval of 2000 meters and single-well group strip gasification zones are arranged in parallel and side by side at intervals of 20-25 meters (the gasification thermal radiation depths of the coal types are respectively 10-12.5 meters along the central line of the gas injection and production well at two sides, the gasification widths of the coal layers are different when the coal types are gasified), the single-well group gasification furnace groups are arranged in parallel side by side to form a 2000-meter-width block gasification working face with a gas injection well 20 in line and a gas production well 30 in line, gas injection side equipment is arranged in line with gas production side measurement and control well head devices in line, each gas production side well head is integrated into a three-well head (3 in-1, 5-in-1, 8-in-1) special gas collection conveying pipelines are conveyed into a gas heat recovery device to recover gas waste heat, the gas temperature of a gas cooling wellhead gas is over 350 ℃, the gas waste heat is also an unavailable heat energy source, part of the high-temperature heat source recovered heat enters an ORC power generation device to generate power for on-site use and electrolyze water to produce hydrogen, and part of the recovered heat directly enters a designed and matched carbon dioxide stripping tower constant-temperature heat exchanger to circularly and constantly heat an alcohol amine solution in the stripping tower to replace a heat circulation heating boiler matched with a conventional stripping tower. The working surface of all injection and production well groups is a region with possible sedimentation, and the gasification single well groups are arranged in parallel side by side to ensure that the continuous sedimentation can be caused by continuous operation once the sedimentation occurs, so that the land and the ground are favorably leveled, and the coal gas purification, gas separation, power generation device and water electrolysis hydrogen production device matched with the ground must avoid the sedimentation and sliding region caused by the gasification working surface or geological factors.

As shown in fig. 1, 2, and 4, in the present embodiment, step S10 includes: drilling a well on the ground vertical to the ground surface to a first preset depth below the ground surface, and then cementing a surface casing to obtain a vertical well; drilling a well into the vertical well, deflecting at a second preset depth on the vertical well and the coal seam roof to form a track of a deflecting section of the arc-shaped radius directional shaft, drilling to the junction of the coal seam floor and the lower rock stratum, and then cementing through a casing to form a bent well; putting a coiled tubing, a guiding tool and a drilling tool assembly into the vertical well; continuously and circularly injecting oil-based mud into the continuous oil pipe; drilling the coiled tubing, the guiding tool and the drilling tool assembly in the pulverized coal layer along the coal seam bottom plate through the bent well, and drilling on the coal seam bottom plate to form a directional well parallel to the coal seam bottom plate; loosening the guide tool and the drilling tool combination to enable the end port of the coiled tubing to form a nozzle; after the directional well is drilled, the oil-based mud is pumped out of the directional well through the coiled tubing. The gas injection well 20 comprises a vertical well and a curved well, and the vertical depth of the vertical well and the vertical depth of the curved well are less than or equal to 2000 m; the length of the directional well is less than 2400 m. The oil-based mud comprises mineral oil, polyacrylamide thickener, ammonium dodecylbenzene sulfonate, hydroxymethyl cellulose and acrylonitrile-styrene-butadiene copolymerThe specific equivalent is as follows: mineral oil 100%, polyacrylamide thickener 0.3kg/m³Ammonium dodecylbenzenesulfonate 5kg/m³0.3kg/m of hydroxymethyl cellulose³0.5kg/m of an acrylonitrile-styrene-butadiene copolymer³. Based on the scheme, firstly, drilling is carried out on the ground until the first preset depth of the surface casing is drilled, and then the surface casing is well-fixed to obtain a vertical well. And then, continuing to drill the well in the next step, namely drilling the well to the coal seam roof of the vertical well for a certain distance for directional deflection, directionally guiding the bent arc-shaped well to a target spot on the coal seam floor, and then putting the well into an oil well casing to form a technical casing well. And (3) putting the coiled tubing and the underground directional guiding drilling tool combination into the technical casing shaft, starting a slurry pump when the underground drilling tool combination reaches the coal seam target point, and converting the drilling operation into the drilling operation of drilling the coiled tubing of the coal seam directional large-displacement well. The mud pump injects the coal bed oil-based mud into the shaft through the coiled tubing and continuously circulates, the oil-based mud plays a role in lubricating the drill bit and carrying rock debris, so that the drill bit can be conveniently drilled and pumped out, and meanwhile, the wall of the coal bed shaft can be supported, and the collapse of the shaft wall in the shaft is prevented. The vertical well section adopts conventional drilling mud, the coiled tubing drilling of the coal seam large displacement well section adopts coal seam oil-based mud circulation, the deflecting arc-shaped bent well section of the vertical well section and the coal seam directional large displacement well is subjected to medium-radius directional deflecting, the friction force between the deflecting well section and the coal seam causes friction locking in a coal seam shaft of the coiled tubing at a certain large displacement depth, the oil-based mud improves the functions of shaft lubrication, sand carrying, support collapse prevention and leakage prevention, after the coal seam directional well drilling is finished, the releasing tool releases the underground drilling tool to be combined in the coal seam drilling shaft, the oil-based mud in the directional shaft is pumped out through the coiled tubing, after the oil-based mud is pumped out, part of the oil-based mud is arranged on the well wall of the directional well, and the oil-based mud also can play a certain fixed effect on the well wall of the directional well. Thus, the drilling of the pulverized coal layer can be effectively realized, and the collapse can be avoided.

As shown in fig. 1, 2 and 4, in this embodiment, in step S20, a continuous gas injection pipeline is inserted into the bottom hole reaming interaction part of the gas production well through the gas injection well head, slurry in the space at the bottom hole reaming interaction part of the gas production well 30 and the gasification directional well 40 is pumped out through the continuous gas injection pipe, then dry gas is injected into the gas injection well 20 through the continuous gas injection pipeline through the gas injection boiler, the dry gas reaches the nozzle of the continuous gas injection pipeline and heats and purges the gasification shaft and heats the gasification channel of the coal seam, a temperature detection port on the wellhead device of the gas production well 30 detects the gas temperature change state of the well head in real time, when the temperature of the gas production well 30 rises to a certain set parameter, the gas injection boiler is stopped briefly, temperature data in the gas production well 30 is collected on a ground measurement and control wellhead device at the gas production well 30, when the temperature data is greater than a preset value, the injection of the dry gas into the gas injection well 20 is suspended, and a firing element is put into the combustion chamber 50 through the continuous oil pipe, at the same time, the gas injection boiler is started to inject dry gas and oxidant, oxygen, into the gas injection well 20. Meanwhile, ignition ball throwing materials are put into a releasing ball throwing cylinder in a continuous pipe roller, the ignition ball throwing materials are specially made ignition deflagration rubber balls mainly made of butane, a releasing ball throwing device is opened, an air injection boiler is immediately started to be switched into an air injection state, the spherical ignition materials are blown into an inner pipe of the composite continuous pipe and are sprayed out from a nozzle of the continuous pipe to enter a coal bed, meanwhile, pure oxygen gas is injected to enter an air injection manifold, high-temperature dry gas at 300 ℃ enables the spherical ignition materials to be heated and deflagrated, meanwhile, the injected oxygen accelerates the deflagration surrounding coal to ignite the coal in a coal bed gasification channel, a wellhead coal gas online detection instrument collects gas component changes in real time, the injection amount of the injected pure oxygen gas is regulated to accelerate the regulation of the combustion state of the coal, and the continuous gas injection process condition of the coal bed gasification is achieved.

As shown in fig. 1, fig. 2, and fig. 4, in the present embodiment, after step S60, step S70 is further included, and step S70: the generated carbon dioxide gas is transported into the gas injection well 20 through the RTP tube and injected into the combustion chamber 50. The carbon dioxide can be effectively utilized by the above operation, and the carbon dioxide can be injected into the combustion chamber 50 and then reacted in the combustion chamber 50.

Specifically, the combustion chamber includes first chamber, second chamber and third chamber, injects the carbon dioxide gas that will generate into first chamber through gas injection well 20, when withdrawing coiled tubing, gets into second chamber, third chamber etc. in proper order. Through the operation, carbon dioxide can be effectively utilized, and after the carbon dioxide is injected into the first cavity, the reaction stability of the coal continuous combustion, controllable gasification and walking stick pressure gasification processes can be ensured in the continuous pumping-back process of the second cavity and the third cavity.

In embodiments not shown, carbon dioxide may also be used to synthesize starch, to synthesize fertilizers, to be used in oil mining, to inject carbon dioxide into oil wells to drive oil to improve the yield of crude oil (EOR), and to be used in foundry industry, metal smelting industry, biopharmaceutical industry, etc.

The carbon dioxide gas is a very stable molecular structure, and the conventional method is difficult to use to remove CO₂As raw material, can be decomposed only under the action of specific high temperature and catalyst, and the underground coal gasification cavity is just CO₂The decomposition creates conditions, and wet CO reduced in the gas stripping regeneration tower₂The gas is directly reflowed to the gas injection manifold at the side of the gas injection well 20 through a multilayer composite continuous PE (RTP) pipe, so that the CCU is used for capturing carbon dioxide, and the composite RTP pipe has the advantages of pressure resistance, corrosion resistance and convenient connection. The CO is₂CO that returns gas directly to the gas injection well 20 without drying₂The inlet port is connected, and the branch pipeline input valve of gamma-nano alumina powder (which is a catalyst with strong activity) on the gas injection manifold is opened at the same time, and the mixed multiple catalysts and CO are mixed₂Is gathered and conveyed into a first combustion chamber, a second combustion chamber and a third combustion chamber … … of the directional well 40 in the coal bed, the nano-alumina powder is beneficial to improving the speed of converting carbon dioxide into carbon monoxide in the gasification chamber (can be improved by 5-20 times), the carbon dioxide can also enter the temperature regulation and control function of the gasification chamber to obviously improve the combustion heat and the thermal stability, and because a plurality of gathered catalysts (mainly steam and O) are arranged in the combustion chamber 50₂)，CO₂CO under the action of nano alumina powder injected along with₂Respectively reduced to CO + O₂，O₂And is consumed in coal gasification to control O₂The content of the coal gas at the outlet is undetectable or trace, thereby realizing H₂+ CO Total maximization, catalysis of functional CO by means of nano-alumina powders₂The conversion rate to CO is increased by 40% and consequently the carbon conversion rate is increased. Controlling gasification cavity injectionInto O₂Content of, ensure O₂When the combustion chamber 50 is fully consumed, O is contained in the gas of the gas production well 30₂The minimization of the content also prevents the oxidation reaction of CO and realizes the CO in the coal gas₂The content is minimized. Notes O₂Quantity-determining the temperature, O, in the gasification chamber₂High concentration of CO at elevated temperature in the gasification chamber₂Ratio increase, CH₄The content is reduced, the content of CO is reduced, and conversely, when O is used₂When the content decreases, the temperature in the combustion chamber 50 decreases, and CO₂Reduced content of CH₄The content is increased, so that CO and CO in the coal gas are measured₂、O₂、CH₄The content of the (B) can control the temperature of the gasification furnace chamber, thereby adjusting the reasonable gasification state.

As shown in fig. 1, fig. 2, and fig. 4, in the present embodiment, step S80 is further included after step S70, and step S80: the carbon dioxide gas reacts with the nano-alumina catalyst in the combustion chamber 50 at a high temperature to produce carbon monoxide and oxygen. The nano alumina catalyst can decompose carbon dioxide into carbon monoxide and oxygen, so that the conversion of the carbon dioxide is effectively realized, and the direct emission of the carbon dioxide is avoided.

In this example, two reactions take place in the combustion chamber:

coal and gasifying agent generate primary pyrolysis and gasification reaction (heating-high temperature):

from the above primary reaction, an excess of oxygen O was observed₂The injection will raise the temperature in the combustion chamber 50, and the oxygen O₂Is also a core catalyst for promoting the conversion and gasification of coal which passes through a gasification agent, namely oxygen O₂And water vapor H₂The primary gasifying agent reacts with carbon through heating, decomposition and gasification under the action of O, and the CO + H is used as the coal gas component in the high-temperature field environment₂+CO₂+CH₄Is the main reaction.

The coal reactant and coal, and the primary reactant have secondary reaction again (high temperature-medium and low temperature):

this process is also carbon dioxide CO₂In the process of converting and reducing the high temperature into the carbon monoxide CO, the deep coal in the combustion chamber 50 is subjected to a plurality of chain reactions with the aid of the pure oxygen gasifying agent and the auxiliary catalyst, and the finally produced coal is subjected to the underground gasification process as follows:

coal (high temperature, high pressure, gasifying agent, catalyst) → C + CH₄+CO+CO₂+H₂+H₂O；

The secondary reaction mainly takes place in the reduction zone of the gas flow due to the large amount of oxygen O₂And water vapor H₂O injection, wherein excessive injected oxygen and water vapor flow into a slag area of gasified coal during gasification reaction, and the excessive water vapor converts carbon monoxide CO into carbon dioxide CO under the action of excessive oxygen₂Therefore, the gasification process is to control the hydrogen H in the coal gasification₂Maximizing the sum of CO and carbon monoxide, minimizing the content of carbon dioxide in the coal gas, and controlling the synthesis of methane CH₄The minimized process is that the on-line real-time detection of the coal gas at a production well head is to control the oxygen O₂And water vapor H₂The trace or undetected O exists, because of the existence of a pure oxygen gasification high-temperature field, the gas does not generate nitride and methane is difficult to retain, and the aim of gas regulation becomes to control the main component H in the gas₂+CO+CO₂To the maximum, the other components are trace or undetectable, actually hydrogen and carbon monoxide (H)₂+ CO) is maximized so that CO₂The content is as low as possible.

During the gasification process, useless compounds generated by the reaction accompanied with other chemical elements in the coal components are removed in the ground purification link, such as sulfide H₂S，SO₂Tar, etc.

As shown in fig. 1 to 4, in the present embodiment, in step S50, the inside of the decarbonizing tower 80 includes a spiral spray pipe 81, the alcohol amine solution lean solution is injected into the spray pipe 81, and the carbonic anhydrase catalyst is spray-cured on the inner wall of the decarbonizing tower 80 and the outer wall of the spray pipe 81. The operation can effectively convert the carbon dioxide in the coal gas into the alcohol amine solution rich solution, and the carbon dioxide absorption speed and efficiency can be improved by adding the carbonic anhydrase catalyst. The method is an important part in the carbon capture and gas stripping, namely the utilization process, the carbon dioxide in the high-pressure coal gas is absorbed by using 30% of alcohol amine solution barren solution, the alcohol amine solution barren solution is used for circularly utilizing a catalyst to purify the carbon dioxide in the coal gas through a spray pipe 81, the formed alcohol amine solution rich solution enters a gas stripping tower 90 to be heated and decomposed to obtain the carbon dioxide, and the alcohol amine solution rich solution enters a carbon dioxide gas stripping tower 90 to be heated and heat source comes from a heat recovery heat exchanger and a heat recovery dust removal cooler.

MDEA+CO₂→MDEA－CO₂Alcohol amine solution absorbs and releases CO₂

As shown in fig. 1, 2, and 4, in the present example, in step S60, γ -nano titanium oxide was added to the stripper 90. The nanometer titanium oxide can improve the decomposition speed and efficiency of the rich solution of the alcohol amine solution.

As shown in fig. 1, fig. 2, and fig. 4, in the present embodiment, in step S60, the rich alcohol amine solution is decomposed to generate the lean alcohol amine solution, and the lean alcohol amine solution is transported to the decarbonizing tower 80 by a pump.

As shown in fig. 1, fig. 2 and fig. 4, in the present embodiment, in step S60, most of the heat obtained by heat exchange is used for cogeneration for on-site use or hydrogen production by electrolysis, and the rest of the heat is transferred to the circulating constant temperature heating heat exchanger at the stripper 90 to replace the conventional stripper circulating heating boiler. The operation can effectively improve the utilization of waste heat and avoid the waste of energy. The recovered heat energy can be used for ORC power generation and stripping regeneration after carbon dioxide capture, the cost of carbon dioxide capture and reuse can be effectively reduced, power supply is also required for application equipment and field lighting in the coal gas purification process, and especially huge power supply can be generated by high-temperature coal gas heat when a plurality of gasification wells run. The device is characterized in that tar in the gas is prevented from being cooled and condensed on the inner wall of the device and the spiral coil to form a heat insulation layer in order to avoid the temperature reduction of the gas, and the gas purification system controls the temperature of the gas at the outlet of the heat exchange cooling tower to be within the range of 80-110 ℃ when being used in multi-stage series connection.

As shown in fig. 1, 2, and 4, in the present embodiment, in step S40, limestone water is injected into the desulfurization tower 70 so that the limestone water performs desulfurization treatment on the gas. The limestone water solution reacts with sulfur to generate sulfate-gypsum, part of carbon dioxide reacts with limestone water to form carbonate, and simultaneously the limestone water solution collides with coal gas dust and tar to realize the functions of desulfurization, dust removal and tar removal. The desulfurization compound, the coal gas dust and the tar collide in rotation to form a raindrop-shaped mixture, and the raindrop-shaped mixture is settled and discharged. Limestone water also reacts with carbon dioxide as a desulfurization solution, but it does not affect the gas deacidification treatment function.

As shown in fig. 1, 2, and 4, in the present embodiment, in step S30, the cooling tower 60 can perform dust removal processing on the coal gas. Dust in the coal gas can be precipitated, and then the dust removal treatment of the coal gas is realized.

As shown in fig. 1, 2 and 4, in the present embodiment, in step S10, the gas is rotated downward in the cooling tower 60 by centrifugal force, moves upward at the conical structure contacting the bottom of the cooling tower 60, and the solid dust particles in the gas are discharged through the bottom of the cooling tower 60. The operation can ensure the dust removal effect of the coal gas.

The pressure-maintaining gasification technology of underground deep coal adopts pure oxygen gasification, and the combustion, gasification and reduction processes of coal are accelerated by high-pressure pure oxygen gasification in a medium-deep coal bed, so that the gas injection cost is increased, but the unit coal gas production cost is actually reduced, and therefore the main component in the high-pressure synthetic coal gas is H₂、CO、CO₂、H₂S is more than 98 percent, and other components form a synthetic gas component by alkyl hydrocarbon. The invention aims to purify and remove acid gas in synthetic high-pressure coal gas generated in the in-situ pressure-maintaining gasification process of deep coal, namely, hydrogen sulfide gas in the coal gas is removed, carbon dioxide in the coal gas is removed, and CO is absorbed₂The regeneration carbon dioxide gas is separated out by thermal decomposition of the rich alcohol amine solution in the stripping device under the catalysis of the gamma titanium oxide in the stripping device. The regenerated carbon dioxide gas is directly conveyed into a gas injection manifold of a gas injection wellhead in a wet carbon dioxide form through an reinforced corrosion-resistant composite PE flexible continuous rubber tube RTP without dehydration, and CO₂The gas is adjusted and mixed by a gas injection manifold and is conveyed into the underground coal bed gasification furnace cavity, and the gas is decomposed into carbon monoxide by reacting with oxygen in the high-temperature high-pressure gasification furnace under the catalysis of gamma-gasified aluminum, so that the content of the carbon monoxide in the gas is increased, and the capture and utilization of the carbon dioxide are realized.

As shown in fig. 1, fig. 2 and fig. 4, in this embodiment, the pressure in the combustion chamber needs to be controlled, and the pressure in the gasification combustion chamber 50 can be ensured by adjusting the primary and secondary electronic control valves on the gas measurement and control wellhead device of the gas injection well 20 to regulate and control the gas production well 30, so that pressure-maintaining gasification is realized. Meanwhile, the efficiency of coal gasification can be further ensured and the pressure in the combustion chamber 50 can be continuously kept relatively stably because the gas injection amount is controlled in real time.

As shown in fig. 1, fig. 2 and fig. 4, in the present embodiment, the technical solution of the present embodiment further includes the following steps: step S90: collecting gas injection quantity of a gas injection well 20 and gas production data of a gas production well 30; step S100: and controlling the gas injection amount and the withdrawal amount of the coiled tubing according to the gas production data. The combustion chamber 50 is ignited by injecting gas into the combustion chamber 50 through the coiled tubing, gas injection parameter data of the gas injection working state of the gas injection equipment is collected at the gas injection well 20, gas production data is collected at the gas production well 30, and gas injection quantity and coiled tubing pumpback quantity are adjusted in real time according to the gas production data. The gas production data comprises physical parameters and chemical composition parameters of coal gas according to the content ratio of hydrogen and carbon monoxideThe maximum value of the hydrogen content ratio is determined according to the hydrogen content ratio, the gas injection amount is controlled according to the maximum value of the hydrogen content ratio, the main required effective components in the coal gas are hydrogen and carbon monoxide, and the more important components in the carbon monoxide and the hydrogen are hydrogen. Therefore, it is necessary to ensure that the hydrogen content is the largest in the coal gas, so that the utilization rate of the coal gas is higher. In order to ensure that the hydrogen gas ratio can be maximized, the gas injection amount at the gas injection well 20 needs to be adjusted in real time to maximize the hydrogen gas ratio. The amount of injected gas can of course also be controlled in accordance with the maximization of the co-proportion of the hydrogen content and the carbon monoxide content. As described above, the ratio of the contents of hydrogen and carbon monoxide is maximized by adjusting the gas injection amount of the gas injection well 20. The gas production well 30 is provided with a gas detection and analysis device, gas production data is obtained through the gas detection and analysis device, the gas injection well 20 is provided with a catalyst supply device and a gas injection boiler, and a controller controls the catalyst supply device and the gas injection boiler according to the gas production data. The gas detection and analysis device can detect the components and the proportion of the gas, so that gas production data can be obtained in real time, and the accuracy and the timeliness of the gas production data are guaranteed. The gas injection boiler injects gas into the combustion chamber 50, so that the injected gas is high-temperature gas, which is more convenient for igniting the combustion chamber 50. The pressure in the combustion chamber 50 is controlled to be maintained between 7MPa and 15 MPa. The above pressure range is effective to ensure combustion of the combustion chamber 50. Specifically, in this example, the pressure was kept at 10 MPa. The control of the amount of injected gas is performed on the basis of a relatively stable range of pressure in the combustion chamber 50. The above-mentioned content means that the gasification pressure in the gasification furnace chamber is stably varied within a control range when the combustion chamber 50 is combusted. Thus, the coal can be more fully combusted. And acquiring gas production data at preset time intervals, wherein the preset time is 5-20 seconds. Because the injection parameters of the underground coal gasification quantity need to reach the nozzle of the continuous oil pipe through the pipeline of the longer continuous oil pipe, a series of continuous processes such as coal heating, coal combustion, gasification, reduction and the like also need to be carried out during the coal gasification, and the single-well group measurement and control computer has little meaning on the high sampling rate of the coal gas parameters, the designed sampling rate is 5Sampling at selectable, presettable intervals of seconds, 10 seconds, 15 seconds, or 20 seconds, which can ensure the stability of gas production data. And performing multiple gas production data acquisition within 180 seconds of a measurement and control cycle to form a decision group, analyzing the current decision group to obtain an analysis result, controlling the injection amount of each gas injection parameter and the withdrawal amount of the continuous oil pipe according to the analysis result, and stably keeping the gasification pressure to fluctuate within a control range by measuring and controlling the pressure and the temperature. According to the analysis of the decision group, the control can be more accurate. And comparing the current gas production data with the previous gas production data, and if the comparison results are different, putting the gas production data into a decision group. The above operation enables the control to control the amount of gas injection more promptly. The gas injection monitoring unit monitors and collects the gas injection amount of the gas injection well 20, the controller can be remotely controlled on line through remote equipment, the gas output by the gas production well 30 is high-temperature and high-pressure gas at 350 ℃, the high-temperature gas at 350 ℃ passes through the multistage heat recovery heat exchanger device to realize waste heat power generation, and the controller, the gas injection monitoring unit, the gas production monitoring unit and the gas purification unit are powered. The high-temperature high-pressure gas overflowing from the gas production well 30-port device carries a large amount of sensible heat energy and tiny particle dust of the gas, and the composition (H) of the gas in a single well group is analyzed and predicted₂:35％、CO:41％、CO₂:22.5％、CH₄:1％、O₂:0.2％、H₂0.3 percent of O), and the calculated coal gas mass is about 0.9981Kg/Nm³The specific heat of the coal gas is about 1.3797 KJ/(Nm)³DEG C), the inlet temperature of the wellhead gas entering the high-efficiency heat recovery heat exchanger is 350 ℃, the outlet temperature is 150 ℃, the output of the wellhead gas is 15000-18000 Nm³The sensible heat of the single-well group gas is 4138 MJ/h-4966 MJ/h, the converted electric energy of the single-well group gas is equivalent to 1149 KWh-1379 KWh, the ORC high-temperature power generation efficiency is calculated according to 20%, the on-site power generation equipment is calculated by using 10% of electricity, the sensible heat of the single-well group gasification unit gas is used for ORC power generation capacity of 206 KW-248 KW, and when 5 groups of wells are combined with gas mixed heat recovery and purification treatment, the ORC power generation capacity of 1030 KW-1240 KW is enough to ensure electricity supply for 5 single-well group gasification well site ground gas purification treatment modules and construction sites. If 180 groups of wells in a designed 5-hundred million-ton coal resource block are developed in a rolling modeCogeneration is even more enormous.

The 350 ℃ high-temperature high-pressure gas at the wellhead is a multi-component mixed commodity gas, the gas is used for separating and preparing hydrogen, generating electricity or other coal chemical industry fields, the sensible heat of the gas can only be indirectly recovered in a non-contact way because the gas contains flammable and explosive components such as hydrogen, carbon monoxide and the like, the sensible heat of the gas is far higher than terrestrial heat or conventional low-temperature waste heat, the gas is an excellent continuous heat energy supply resource, and the wellhead gas is directly connected to a heat exchanger to recover the sensible heat in order to avoid the loss of the sensible heat of the gas in a ground pipeline and exposed air. The method comprises the steps that a large amount of dust particles are carried in coal gas due to high-pressure flow, a special high-temperature high-pressure high-dust heat exchanger is required to recover sensible heat of the coal gas without accumulating coal ash dust, a two-stage series high-temperature high-pressure high-dust vortex tube shell heat exchanger absorbs sensible heat (waste heat) of the coal gas, high-temperature heat transfer oil (high-temperature heat transfer oil with the temperature of 350 ℃ or 400 ℃) is adopted to circularly absorb sensible heat of the coal gas, the high-temperature heat transfer oil is controlled to continuously circularly absorb sensible heat pressure, the temperature difference between the temperature of the heat transfer oil entering and exiting the heat exchanger is kept constant at 30 ℃, the temperature of a heat transfer oil outlet is controlled to be stable at 240 ℃ to 250 ℃, the sensible heat transfer oil which flows out of the vortex tube shell heat exchanger and absorbs the sensible heat is conveyed and injected into an ORC evaporator through one branch to evaporate and gasify R245fa, the heat transfer oil which flows out of the evaporator returns to a heat transfer oil buffer oil tank at the heat transfer oil inlet of the vortex tube shell heat exchanger through a circulating pump, and then one circulation of an ORC heat source is formed between the heat transfer oil and the heat exchanger. The ORC organic working medium R245fa is continuously evaporated and circularly gasified in the evaporator by heat conduction oil entering the evaporator, the evaporated organic working medium R245fa enters an organic working medium double-screw expander (turbine) to push a generator to generate continuous power, ORC instant power generation electric energy can be used for construction sites, and each group of ORC power generation system can ensure that 5 single-well group gasification units share the power supply of a gas purification system. The surplus power can be used for charging the energy storage device. The other path of the heat transfer oil for absorbing the sensible heat of the coal gas enters a rich liquid heat exchanger of a carbon dioxide gas stripping regeneration tower to heat the alcohol amine solution to maintain the constant temperature of the solution in the stripping tower, replaces the function of a conventional circulating reheating boiler of the stripping tower,

it should be noted that the material injected at the gas injection well 20 includes a catalyst, and the catalyst can effectively control the composition of the gas generated by coal gasification.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A coal gas purification and carbon dioxide circulation treatment method is characterized by comprising the following steps:

step S10: determining the stratum depth and the stratum inclination angle of a coal layer (10), drilling a gas injection well (20) and a gas production well (30) at the determined well position of the coal layer (10), drilling a directional well (40) in the coal layer (10) so that the directional well (40) is communicated with the gas injection well (20) and the gas production well (30), forming an interactive well bottom at the joint of the directional well (40) and the gas production well (30), and forming a combustion cavity (50) at the rear end of the interactive well bottom;

step S20: injecting gas into the directional well (40) through a gas injection well (20) to ignite the combustion chamber (50) and produce gas;

step S30: the coal gas sequentially enters a heat exchanger (100) and a cooling tower (60) through the gas production well (30) for heat exchange;

step S40: the coal gas after heat exchange enters a desulfurizing tower (70) for desulfurization treatment to form a sulfate solution, part of carbon dioxide is absorbed simultaneously to form a mixed solution of a carbonate solution and a sulfate, and the mixed solution of the sulfate and the carbonate is cached and injected underground;

step S50: the coal gas after desulfurization enters a decarbonizing tower (80) to convert carbon dioxide in the coal gas into alcohol amine solution rich solution;

step S60: conveying the rich alcohol amine solution to a stripping tower (90), and decomposing the rich alcohol amine solution in the stripping tower (90) through a catalyst to produce carbon dioxide gas;

wherein in the step S60, the heat of the gas entering the heat exchanger (100) and the cooling tower (60) for heat exchange is transferred to the stripping tower (90) to heat the stripping tower (90) so as to keep the stripping tower (90) at a constant temperature.

2. The gas purification and carbon dioxide recycling method as claimed in claim 1, further comprising a step S70 after the step S60,

the step S70: the generated carbon dioxide gas is transported into the gas injection well (20) through an RTP pipe and injected into a combustion chamber (50).

3. The gas purification and carbon dioxide recycling method as claimed in claim 2, further comprising a step S80 after the step S70,

the step S80: the carbon dioxide gas is reduced into carbon monoxide and oxygen in the combustion chamber (50) under the action of a nano alumina catalyst and high temperature.

4. The gas purification and carbon dioxide recycling method according to claim 1, wherein in step S50, the decarbonizing tower (80) includes a spiral spray pipe (81), the spray pipe (81) is filled with the alcohol amine lean solution, and the carbonic anhydrase catalyst is sprayed and solidified on the inner wall of the decarbonizing tower (80) and the outer wall of the spray pipe (81).

5. The gas purification and carbon dioxide recycling process according to claim 1, wherein in step S60, nano-titania is added to the stripper (90).

6. The gas purification and carbon dioxide recycling method as claimed in claim 1, wherein in step S60, the rich solution of alcohol amine solution is decomposed to generate lean solution of alcohol amine solution, and the lean solution of alcohol amine solution is transported to the carbon removal tower (80) by a pump.

7. The gas purification and carbon dioxide recycling method according to claim 1, wherein in step S60, a part of the heat obtained by the heat exchange is used for cogeneration, and the remaining part of the heat is transferred to the stripper (90).

8. The gas purification and carbon dioxide recycling method as claimed in claim 1, wherein limestone water is injected into the desulfurization tower (70) so that the limestone water desulfurizes the gas in step S40.

9. The gas purification and carbon dioxide recycling method as claimed in claim 1, wherein in step S30, the cooling tower (60) is capable of performing a dust removal process on the gas.

10. The gas cleaning and carbon dioxide recycling method of claim 1, wherein in step S30, the gas is rotated downward in the cooling tower (60) by centrifugal force, and moves upward at the conical structure contacting the bottom of the cooling tower (60), and the solid dust particles in the gas are discharged through the bottom of the cooling tower (60).