In-situ controllable direct combustion power generation-gasification combined mining method and system for coal

Abstract

The application provides a coal in-situ controllable direct combustion energy extraction-gasification combined mining method and system. A directional drilling bit is installed at the end of an air inlet pipe. Geological structures such as fracture zones and faults are identified during drilling. The coal seam gangue condition is obtained through backflow of the slag. The air inlet pipe is driven to move in the coal seam to control the oxidant content of the oxygen release section in different regions and control the combustion process. Secondly, after the coal in the horizontal well is completely combusted to form a combustion empty area, the drilling direction is adjusted. Oxygen-rich oxidants or protective gases for controlling the intense combustion of coal are provided for the combustion of coal in any direction of the coal seam. The coal far away from the horizontal well continues to combust to form a new combustion area, thereby reducing the arrangement of the horizontal well and the horizontal pipeline. Further, the full-range mining in the coal seam can be realized through one horizontal well, without the need to open another horizontal well. The full combustion and mining of the coal in each direction of the coal seam can be fully ensured, and the efficiency of the in-situ coal mining is effectively improved.

Description

Technical Field

[0001] This application relates to the field of energy extraction technology, and in particular to a method and system for in-situ controlled direct combustion energy extraction and gasification combined mining of coal. Background Technology

[0002] In coal mining, traditional mechanical methods—such as blasting and cutting coal with tools—pose significant challenges to maintaining the stability of the surrounding rock, resulting in complex mining systems and enormous energy consumption. In contrast, chemical coal mining involves artificially inducing chemical reactions in the coal-bearing strata to extract the useful chemical components of the raw coal. This unmanned and intelligent method fundamentally changes traditional coal mining practices, enabling unmanned underground mining, coal-free surface mining, and fluidized product production.

[0003] Currently, the chemical mining methods for coal are mainly divided into three technologies: underground gasification, underground pyrolysis, and biodissolution. For underground coal gasification, the reactions during the gasification process are difficult to control, leading to large fluctuations in the composition of the syngas. It is also susceptible to water leakage and gas exchange between wells due to the influence of coal seams and geological conditions. Furthermore, the composition of the gasified gas is unstable. In addition, coal gasification may produce large amounts of carbon dioxide, which is difficult to manage and can have a certain impact on the environment. The efficiency of underground coal gasification is also relatively low, requiring a large amount of oxygen and heat, resulting in high costs.

[0004] Underground coal pyrolysis presents several challenges. First, it is significantly influenced by geological conditions. Underground pyrolysis requires deep underground penetration, demanding specific geological conditions that can affect the pyrolysis efficiency and product quality. Second, the pyrolysis process is difficult to control. Underground pyrolysis necessitates precise control of temperature, pressure, and other conditions to maintain suitable chemical reaction conditions; otherwise, product quality and yield may be compromised. Third, underground pyrolysis causes substantial environmental pollution. The process may generate harmful gases and liquids such as carbon dioxide and hydrogen sulfide, which, if not properly managed, can cause significant environmental pollution.

[0005] The biodissolution of coal is not only slow, but also causes several environmental problems. For example, the bacteria that dissolve coal are difficult to cultivate, and when released directly into the bottom layer, the pollution to soil and groundwater is immeasurable.

[0006] Therefore, there is an urgent need to provide a technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0007] The purpose of this application is to provide a method and system for in-situ controlled direct combustion energy extraction and gasification of coal, so as to solve or alleviate the problems existing in the above-mentioned prior art.

[0008] To achieve the above objectives, this application provides the following technical solution:

[0009] This application provides a method for in-situ controlled direct combustion energy extraction and gasification combined mining of coal, comprising: constructing an injection well and a production well downwards from the surface of the coalfield; wherein the injection well penetrates the overburden and reaches the middle of the coal seam, serving as the starting point of the mining area; the production well is completed in one drilling operation, serving as the ending point of the mining area; a bundle of tubes is used from the injection wellhead to the mining area; wherein the middle of the bundle of tubes is a working fluid inflow pipe, which is surrounded by multiple air inlet pipes, the ends of which are connected to a directional drilling bit and advance deeper into the coal seam as the coal seam mining progresses; the section of the air inlet pipe near the drill bit is an oxygen release section, and the surface of the oxygen release section has multiple release holes to dissipate the oxidant; the bundle of tubes in the injection well extends smoothly into the horizontal well. Furthermore, an ignition heating device is installed at the end of the working fluid inflow pipe; in the horizontal well, a gasification product collector is installed at a predetermined distance from the end of the inlet pipe in the forward direction; the gasification product collector is arranged around the working fluid horizontal pipe in the horizontal well and is connected to a gas chromatograph through the gasification product collection pipe to generate gasification products; both ends of the working fluid horizontal pipe are connected to the working fluid inflow pipe and the working fluid outflow pipe respectively, and the other end of the working fluid outflow pipe and the other end of the working fluid inflow pipe are connected to a heat exchanger or a turbine respectively; after the gas product flowing out of the gasification product collection pipe is analyzed by the gas chromatograph, the gas composition information is fed back to the gas supply control equipment, and the gas supply control equipment controls the amount of oxidant introduced into the inlet pipe.

[0010] Preferably, along the length of the horizontal well, the coal seam is sequentially divided into a combustion zone, an oxygen-enriched combustion zone, a lean oxygenation zone, a reduction zone, and a dry distillation zone; wherein, the oxygen release section is located in the oxygen-enriched combustion zone to release oxidant into the oxygen-enriched combustion zone through a release hole; the gasification product collector moves sequentially in the lean oxygenation zone, the reduction zone, and the dry distillation zone as the coal seam is mined.

[0011] Preferably, the walls of the injection well and the production well are respectively wrapped with thermal insulation material.

[0012] Preferably, the end of the bundle tube with the release hole can move arbitrarily in three-dimensional space, and the oxygen release section of each air inlet pipe can be individually controlled to control the amount of oxidant introduced; in horizontal wells, the gasification product collector can move arbitrarily in three-dimensional space with the directional drilling bit.

[0013] Preferably, the working fluid inlet pipe, the working fluid horizontal pipe, the working fluid outlet pipe, and the gasification product collection pipe all adopt Tesla pipes.

[0014] Preferably, multiple horizontal wells are drilled in the coal seam; the working fluid horizontal pipes of the multiple horizontal wells are connected and share a working fluid inflow pipe and a working fluid outflow pipe.

[0015] Preferably, multiple horizontal working fluid branch pipes are set on the horizontal working fluid pipe at a preset angle.

[0016] Preferably, during coal seam combustion and the period when the temperature of the thermal reservoir is maintained above 100°C, the working fluid is CO2 or supercritical CO2; after the coal seam is burned and the waste heat is extracted, when the temperature of the artificial thermal reservoir reaches 100°C, the working fluid is water.

[0017] This application also provides a coal in-situ controllable direct combustion energy extraction-gasification combined mining system, including: a gas supply unit, a heat exchange unit, a collection unit, and a gas supply control device; the gas supply unit is connected to an intake pipe installed in the injection well, and is used to provide oxidant or inert gas to the coal seam combustion; wherein, a directional drilling bit is installed at the end of the intake pipe that extends into the horizontal well, and multiple release holes are provided near the directional drilling bit; the heat exchange unit includes: a heat exchanger, a working fluid inlet pipe, a working fluid horizontal pipe, and a working fluid outlet pipe, one end of the working fluid inlet pipe is connected to the heat exchanger or a turbine, and the other end extends into the injection well and is connected to one end of the working fluid horizontal pipe, and the working fluid inlet pipe and the working fluid horizontal pipe are connected to each other. An ignition heating device is fitted at the smooth arc connection of the pipe; a gasification product collector is also arranged around the horizontal working fluid pipe; the gasification product collector is set at a predetermined distance from the end of the inlet pipe in the forward direction in the horizontal well; the other end of the horizontal working fluid pipe is connected to the working fluid outlet pipe, and the other end of the working fluid outlet pipe is connected to a heat exchanger or turbine; the acquisition unit includes a gas chromatograph, which is connected to the gasification product collector through the gasification product collection pipe, and after analyzing the gas products flowing out of the gasification product collection pipe, the gas chromatograph feeds back the gas composition information to the gas supply control equipment, which simultaneously controls the amount of oxidant introduced into the inlet pipe by the gas supply unit. Beneficial effects

[0018] In the coal in-situ controllable direct combustion energy extraction-gasification combined mining method provided in this application embodiment, injection wells and production wells are first constructed downwards from the surface of the coalfield. The injection well penetrates the overburden and reaches the middle of the coal seam, the starting point of the unmined area; the production well is completed in one drilling operation, marking the end point of the mining area; a bundle of tubes is used from the injection wellhead to the mining area; the middle of the bundle of tubes is the working fluid inflow pipe, which is surrounded by multiple air inlet pipes. The ends of the air inlet pipes are connected to the directional drilling bit and advance deeper into the coal seam as the coal seam mining progresses. The section of the air inlet pipe near the drill bit is the oxygen release section, and multiple release holes are distributed on the surface of the pipe in the oxygen release section to release the oxidant; the bundle of tubes in the injection well extends smoothly to the horizontal well. In the horizontal well, an ignition heating device is installed at the end of the working fluid inflow pipe. A gasification product collector is installed at a predetermined distance from the end of the inlet pipe in the forward direction. The gasification product collector is arranged around the working fluid horizontal pipe in the horizontal well and is connected to a gas chromatograph through the gasification product collection pipe to generate gasification products. The two ends of the working fluid horizontal pipe are connected to the working fluid inflow pipe and the working fluid outflow pipe, respectively. The other ends of the working fluid outflow pipe and the other ends of the working fluid inflow pipe are connected to a heat exchanger, respectively. After the gas product flowing out of the gasification product collection pipe is analyzed by the gas chromatograph, the gas composition information is fed back to the gas supply control equipment. At the same time, the gas supply control equipment controls the amount of oxidant introduced into the inlet pipe.

[0019] Therefore, firstly, by using a directional drill bit installed at the end of the intake pipe, geological structures such as fracture zones and faults are identified during drilling. The coal seam intercalation situation is obtained through slag return and discharge, which drives the intake pipe to move within the coal seam to control the oxidant content in different oxygen release zones and control the combustion process. Secondly, after the coal seam at the horizontal well is completely burned out and a combustion vacancy zone is formed, the drilling direction is adjusted to provide oxygen-rich oxidant or protective gas to control the intense combustion of coal in any direction of the coal seam. This allows coal far from the horizontal well to continue burning and form new combustion zones, thereby reducing the need for horizontal wells and horizontal pipelines. Furthermore, all-round mining within the coal seam can be achieved through a single horizontal well without the need to open additional horizontal wells, which can fully ensure the combustion and mining of coal in all directions within the coal seam and effectively improve the efficiency of in-situ coal mining.

[0020] Furthermore, the gasification products collector collects the combustion products generated in an aerobic environment. , , The timely collection of combustible gases such as coal gas generated in oxygen-deficient environments avoids energy waste and effectively improves energy utilization. Simultaneously, the heat generated by the spontaneously combusting coal seam is carried away by the heat-extraction medium in the horizontal working fluid pipe, reducing the thermodynamic hazards caused by violent coal combustion. This utilizes the difficult-to-use, dangerous, and spontaneously combustible coal seam, lowering the cost of extinguishing spontaneously combusting coal seams. Attached Figure Description

[0021] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. Wherein:

[0022] Figure 1 This is a schematic flow diagram of a coal in-situ controlled direct combustion energy extraction-gasification combined mining method according to some embodiments of this application;

[0023] Figure 2 This is a schematic diagram of the "111" arrangement under shallow coal seam conditions according to some embodiments of this application;

[0024] Figure 3 This is a schematic diagram of the "1N1" arrangement under deep coal seam conditions according to some embodiments of this application;

[0025] Figure 4 A zoning diagram of in-situ controlled direct combustion energy extraction-gasification combined mining of coal is provided according to some embodiments of this application;

[0026] Figure 5 This is a schematic diagram of a coal in-situ controllable direct combustion energy extraction-gasification combined mining system provided according to some embodiments of this application. Detailed Implementation

[0027] The present application will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present application without departing from the scope or spirit thereof. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present application encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0028] With the development of technology, in response to the problems existing in underground gasification, underground pyrolysis, and biodissolution during the chemical mining of coal, the in-situ combustion energy extraction method of coal reservoirs has been proposed to safely and efficiently utilize coal resources under environmentally friendly conditions. Existing technologies, for thermal coal, have achieved controlled and continuous in-situ combustion of coal seams, fully extracting and utilizing combustion heat, and burying carbon in-situ underground. However, this method has two limitations: firstly, combustion can only proceed along the horizontal well direction, and coal seam areas far from the horizontal well cannot be effectively mined, requiring the relocation of horizontal wells; secondly, coal is generated in an aerobic environment. 、 、 Gasification products such as coal gas generated in oxygen-deficient environments are released and not fully utilized.

[0029] Based on this, this application proposes a method for in-situ controlled direct combustion energy extraction and gasification combined mining of coal, such as... Figures 1 to 4 As shown, the in-situ controlled direct combustion energy extraction-gasification combined mining method for coal includes:

[0030] Step S101: Drill injection wells and production wells downwards from the surface of the coalfield. The injection wells penetrate the overburden and reach the middle of the coal seam, which is the starting point of the mining area. The production wells are drilled in one go and are the ending point of the mining area.

[0031] In this application, the walls of the injection well and production well are respectively wrapped with thermal insulation material, which effectively reduces heat exchange between the high-temperature working fluid, gasification products, and overburden, increases the heat-carrying capacity of the working fluid, and prevents the gasification products from cooling down and producing viscous, semi-solidified coal tar that clogs the pipeline, thus ensuring that coal is generated in an aerobic environment. 、 、 Gasification products such as coal gas generated in oxygen-deficient environments can be collected smoothly.

[0032] Step S102: The wellhead of the injection well to the mining area adopts a bundled tube arrangement. The middle of the bundled tube is the working fluid inflow pipe. The working fluid inflow pipe is surrounded by multiple air inlet pipes. The end of the air inlet pipe is connected to the directional drilling bit. As the coal seam mining progresses, it is pushed deeper into the coal seam. The section of the air inlet pipe near the drill bit is the oxygen release section. Multiple release holes are distributed on the surface of the pipe in the oxygen release section to release the oxidant.

[0033] In this application, the coal seam is sequentially divided along the length of the horizontal well into four zones: combustion zone I, oxygen-enriched combustion zone II, oxygen-deficient oxidation zone III, reduction zone IV, and dry distillation zone V. Simultaneously, a gas supply station is constructed on the surface of the coalfield. The gas supply station's pipeline is connected to the intake pipe, and the oxygen release section is located in the oxygen-enriched combustion zone. The gas supply station provides oxygen-enriched oxidants or protective gases (inert gases) to control the intense combustion of coal.

[0034] The combustion zone is defined as the slag and a small amount of char left after the coal seam has been fully burned. In the oxygen-rich combustion zone, carbon, methane, and carbon monoxide undergo multiphase chemical reactions with oxygen in an oxygen-rich environment, generating a large amount of heat energy. The reservoir temperature and pressure rise rapidly, and the gas flow, driven by pressure, moves towards the oxygen-deficient oxidation zone of the coal seam further ahead. In the oxygen-deficient oxidation zone, a small amount of oxygen flows into the coal seam with the pressure, undergoing pyrolysis and slow oxidation reactions, generating a small amount of heat, but not enough to completely oxidize the coal. The high-temperature gas flow continues to move forward in the direction of coal seam combustion, reaching the reduction zone.

[0035] In the reducing zone, the coal body undergoes heat conduction and radiation, and the temperature reaches [temperature value missing]. Carbon dioxide reacts with the hot coal, reducing it to carbon monoxide. Simultaneously, water vapor in the reservoir reacts with carbon to produce carbon monoxide, hydrogen, and small amounts of hydrocarbon gases. As the gas flow passes through the reduction zone, its temperature gradually decreases until the reduction process ceases, and the oxygen-free, high-temperature gas flow enters the main drying zone.

[0036] In the dry distillation zone, when the oxygen-free, high-temperature gas stream enters the dry distillation zone, the heat causes the volatile components and water vapor in the coal to be released. The mixed coal gas moves towards the production well and is further pyrolyzed to generate carbon monoxide, hydrogen, and light hydrocarbons.

[0037] In this application, combustion and heat extraction are mainly carried out in the oxygen-enriched combustion zone. The oxygen-enriched atmosphere generates a large amount of carbon dioxide and heat, which then undergoes a coal gasification reaction after the raw coal is dried. Therefore, the gas produced at the outlet is mostly carbon dioxide. A small portion of 、 And other gases.

[0038] A directional drill bit installed at the end of the intake pipe identifies geological structures such as fracture zones and faults during drilling. The coal seam intercalation is determined by backfilling slag, allowing the intake pipe to move freely within the three-dimensional space of the coal seam. Furthermore, the oxygen release section of each intake pipe can be individually controlled by the gas supply control equipment at the gas supply station, effectively controlling the combustion process. The oxygen supply is regulated by the gas supply control equipment, and gas chromatograph measurements show... When the content is less than 50%, the gas supply control equipment automatically increases the oxygen supply. At the same time, in the oxygen-deficient gasification zone, reduction zone, and dry distillation zone, gasification products are generated under the oxygen-deficient environment and collected by the gasification product collector. It should be noted that the structural shape of the gasification product collector is not limited. In a specific example, the gasification product collector can adopt a funnel-shaped structure, with the small end connected to the gasification product collection pipe.

[0039] In this application, the directional drilling bit drives the air intake pipe to move arbitrarily within the three-dimensional space of the coal seam. After the coal seam at the horizontal well has burned out and formed a combustion vacancy zone, the drilling direction is adjusted to provide oxygen-rich oxidant (or protective gas to control the intense combustion of coal) for combustion in any direction of the coal seam. This allows coal far from the horizontal well to continue burning and form new combustion zones, thereby reducing the need for horizontal wells and pipelines. Consequently, omnidirectional mining within the coal seam can be achieved through a single horizontal well, eliminating the need for additional horizontal wells. This ensures sufficient combustion and mining of coal in all directions within the coal seam, effectively improving the efficiency of in-situ coal mining. Simultaneously, when the coal seam is burning intensely, the directional drilling bit can move towards the area of ​​intense combustion, introducing protective gas to control the intense combustion of coal and releasing inert gas for fire extinguishing, effectively preventing uncontrolled combustion of the coal seam.

[0040] Step S103: The bundle of tubes in the injection well extends smoothly into the horizontal well, and an ignition heating device is fitted at the end of the working fluid inflow pipe; in the horizontal well, a gasification product collector is set at a preset distance from the end of the inlet pipe in the forward direction. The gasification product collector is arranged around the horizontal working fluid pipe in the horizontal well and is connected to the gas chromatograph through the gasification product collection pipe to generate gasification products.

[0041] In this application, the two ends of the working fluid horizontal pipe are connected to the working fluid inlet pipe and the working fluid outlet pipe, respectively. The other end of the working fluid outlet pipe and the other end of the working fluid inlet pipe are connected to a heat exchanger or a turbine, respectively. By using the heat-extracting medium in the working fluid horizontal pipe to remove the heat generated by the spontaneously combusting coal seam, the thermal dynamic hazards caused by the violent combustion of coal are reduced, the difficult-to-use and dangerous spontaneously combustible coal seams are utilized, and the fire extinguishing cost of spontaneously combusting coal seams is reduced.

[0042] In one application scenario, the working fluid outflow pipe is also connected to the external circulation pipe. The external circulation pipe generates electricity through a turbine or extracts heat from a heat exchanger (the turbine and heat exchanger are connected in parallel). Two valves are set on the branches of the parallel pipe to control the passage and disconnection of the pipe. After the parallel pipes converge into the external circulation pipe, they are connected to the working fluid inflow pipe. Working fluid control equipment is set on both sides of the turbine generator or heat exchanger. The working fluid inlet is set on the air inlet side of the external circulation pipe. Due to the addition of working fluid and the compensation after the working fluid circulation loss.

[0043] The heat exchange equipment for power generation (turbine generator or heat exchanger) utilizes the heat carried by the working fluid. However, if the temperature of the working fluid is too high or too low, the heat exchange equipment will not be fully utilized. Therefore, the flow valve is regulated by the working fluid control equipment. When the temperature of the working fluid is too high, the working fluid flow rate is increased by the working fluid control equipment; when the temperature of the working fluid is too low, the working fluid flow rate is decreased by the working fluid control equipment.

[0044] In a specific example, multiple working fluid horizontal branches are set on the working fluid horizontal pipe at a preset angle. Each working fluid horizontal branch forms a certain angle with the working fluid horizontal pipe, and the multiple working fluid horizontal branches are evenly distributed on the working fluid horizontal pipe to effectively increase the contact area with the coal seam and improve the heat exchange efficiency.

[0045] In shallow coal seams (less than 800 meters), each working fluid horizontal pipe is matched with one working fluid inlet pipe and one working fluid outlet pipe, arranged in a "111" pattern. This means that one horizontal well in the coal seam corresponds to one injection well and one production well. Due to the low stress at the bottom of the shallow coal seam, the injection and production wells have shorter operating lengths and less heat exchange with the coal and rock, effectively improving heat utilization.

[0046] In deep coal seams (over 800 meters), laying numerous vertical shafts is not only technically challenging but also extremely costly. This application addresses this by constructing multiple horizontal shafts within the coal seam. These horizontal shafts are interconnected, sharing a single inlet and outlet pipe for the working fluid. In other words, after multiple horizontal pipes are interconnected, they are connected to the same inlet and outlet pipe. This means that, under deep conditions, multiple interconnected horizontal shafts share a single injection well and a single production well, forming a "1N1" configuration. This effectively avoids the technical and cost problems associated with laying numerous vertical shafts. Furthermore, with only one production well, the overall length of the vertical shaft is effectively reduced, significantly decreasing the energy required for heat exchange between the shaft and the rock mass when the working fluid flows to the surface.

[0047] In a specific application scenario, two mining areas are symmetrically arranged, using the same vertical shaft (the same injection shaft or the same production shaft), which effectively improves the utilization efficiency of the shaft. When the coal quality is good and easy to produce, introducing a small amount of oxidant is enough to keep the coal seam burning and generate a large amount of heat; using the same injection shaft can meet the oxidant supply requirements. When the coal quality is poor and not conducive to production, introducing a large amount of oxidant keeps the coal seam burning, but generates less heat; using the same production shaft can meet the production requirements.

[0048] In this application, the inlet pipe, working fluid inlet pipe, working fluid outlet pipe, working fluid horizontal pipe, and gasification product collection pipe are all made of high-temperature alloy steel to improve high temperature resistance and deformation performance. Furthermore, the working fluid inlet pipe, working fluid horizontal pipe, working fluid outlet pipe, and gasification product collection pipe all adopt Tesla pipes, so that the working fluid can only flow counterclockwise (i.e., flow along the direction of coal seam advancement), effectively preventing the backflow of working fluid and gasification product fluid due to high internal temperature and pressure after combustion of the mining unit.

[0049] The gasification product collector is arranged relative to the end of the inlet pipe, around the horizontal working fluid pipe, and can move freely in three-dimensional space with the directional drilling bit. Specifically, driven by the gasification product collection pipe, the gasification product collector moves sequentially along the axial direction of the horizontal well through the oxygen-deficient oxidation zone, reduction zone, and dry distillation zone as the coal seam is mined, collecting the gasification product products generated during combustion in an aerobic environment. , , The timely collection of gases such as coal gas generated in oxygen-deficient environments avoids energy waste and effectively improves energy utilization.

[0050] Step S104: After the gaseous product flowing out of the gasification product collection pipe is analyzed by a gas chromatograph, the gas composition information is fed back to the gas supply control equipment, and the gas supply control equipment controls the amount of oxidant introduced into the gas inlet pipe.

[0051] In this application, combustion and heat extraction are mainly carried out in the oxygen-enriched combustion zone. The oxygen-enriched atmosphere generates a large amount of carbon dioxide and heat, which then undergoes a coal gasification reaction after the raw coal is dried. Therefore, the gas produced at the outlet is mostly carbon dioxide. A small portion 、 And other gases, when measured by gas chromatography When the content is less than 50%, the gas supply control equipment automatically increases the oxygen supply. At the same time, the oxygen-deficient gasification zone, reduction zone, and dry distillation zone will produce gasification products in the oxygen-deficient environment, which are collected by the gasification product collector.

[0052] The working fluid used varies at different stages of combustion. During coal seam combustion and the later period when the reservoir temperature remains above 100℃, the working fluid introduced is... or supercritical At this time, due to The reduced density of the working fluid inside the horizontal tube due to heat, coupled with the pressure difference between the injection wellhead and the horizontal tube, accelerates the process. The flow of the working medium in the pipelines (working medium inlet pipe, working medium horizontal pipe, working medium outlet pipe), while utilizing... With excellent heat carrying capacity, it quickly transfers the heat generated by coal combustion to the turbine for power generation through the external circulation pipe. After the coal seam is burned and the waste heat is extracted, the artificial heat storage formed reaches a temperature of 100°C. Water is then introduced as the working fluid, and it flows into the heat exchanger through the working fluid outlet pipe for heat exchange.

[0053] As a special type of coal, spontaneously combusting coal can cause violent combustion and generate thermodynamic hazards under natural conditions. By using a heat exchange medium in a horizontal working tube to remove the heat generated by the spontaneously combusting coal seam, the heat can be exchanged through a heat exchanger or used to generate electricity through a turbine. This not only reduces the thermodynamic hazards caused by the violent combustion of coal and solves the problem of the danger to people caused by the easy combustion of spontaneously combusting coal, but also makes use of the difficult-to-use and dangerous spontaneously combusting coal seam, reducing the cost of extinguishing spontaneously combusting coal seams. At the same time, it can make full use of its flammable properties to reduce the amount of oxidizer introduced, making it easier for the coal seam to continue burning.

[0054] This application also provides a coal in-situ controllable direct combustion energy extraction-gasification combined mining system, such as... Figure 5 As shown, the coal in-situ controllable direct combustion energy extraction-gasification combined mining system includes: a gas supply unit, a heat exchange unit, a data acquisition unit, and gas supply control equipment.

[0055] The gas supply unit (oxidant, inert gas) is connected to the air intake pipe installed in the injection well to provide oxidant or inert gas for coal seam combustion; wherein, the end of the air intake pipe that extends into the horizontal well is equipped with a directional drilling bit, and multiple release holes are provided near the directional drilling bit.

[0056] The heat exchange unit includes a heat exchanger, a working fluid inlet pipe, a working fluid outlet pipe, and a working fluid horizontal pipe. One end of the working fluid inlet pipe is connected to the heat exchanger or a turbine, and the other end extends into the injection well and connects to one end of the working fluid horizontal pipe. An ignition heating device is fitted at the smooth arc connection between the working fluid inlet pipe and the working fluid horizontal pipe. A gasification product collector is also arranged around the working fluid horizontal pipe. The gasification product collector is located in the horizontal well at a predetermined distance from the end of the inlet pipe in the forward direction. The other end of the working fluid horizontal pipe is connected to the working fluid outlet pipe, and the other end of the working fluid outlet pipe is connected to the heat exchanger or a turbine.

[0057] The acquisition unit includes a gas chromatograph, which is connected to a gasification product collector via a gasification product collection tube. After analyzing the gas products flowing out of the gasification product collection tube, the gas chromatograph feeds back the gas composition information to the gas supply control equipment, which then controls the amount of oxidant supplied by the gas supply unit to the inlet pipe.

[0058] The coal in-situ controllable direct combustion energy extraction-gasification combined mining system provided in this application embodiment can realize the steps and processes of any of the above-mentioned coal in-situ controllable direct combustion energy extraction-gasification combined mining methods, and achieve the same technical effect, which will not be repeated here.

[0059] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for in-situ controlled direct combustion energy extraction and gasification combined mining of coal, characterized in that, include: In the mining of coalfields, injection wells and production wells are drilled downwards from the surface. The injection well penetrates the overburden and reaches the middle of the coal seam, marking the starting point of the mining area. The production well is drilled in one go, marking the end point of the mining area. The injection wellhead to the mining area adopts a bundled tube arrangement; the middle of the bundled tube is the working fluid inlet pipe, which is surrounded by multiple air inlet pipes. The end of the air inlet pipe is connected to the directional drilling bit and advances into the deeper part of the coal seam as the coal seam mining progresses. The section of the air inlet pipe near the drill bit is the oxygen release section. The surface of the oxygen release section has multiple release holes to release the oxidant. The end of the bundled tube with release holes can move arbitrarily in three-dimensional space, and the oxygen release section of each air inlet pipe can independently control the amount of oxidant introduced. The injection tube bundle extends smoothly into the horizontal well via a circular arc, and an ignition heating device is fitted at the end of the working fluid inlet pipe. In the horizontal well, a gasification product collector is installed at a predetermined distance from the end of the air inlet pipe in the forward direction. The gasification product collector can move arbitrarily in three-dimensional space with the directional drilling bit. The gasification product collector is arranged around the working fluid horizontal pipe in the horizontal well and is connected to a gas chromatograph through the gasification product collection pipe to generate gasification products. The two ends of the working fluid horizontal pipe are connected to the working fluid inlet pipe and the working fluid outlet pipe, respectively. The other end of the working fluid outlet pipe and the other end of the working fluid inlet pipe are connected to a heat exchanger or a turbine, respectively. The gaseous products flowing out of the gasification product collection pipe are analyzed by a gas chromatograph, and the gas composition information is fed back to the gas supply control equipment. At the same time, the gas supply control equipment controls the amount of oxidant introduced into the gas inlet pipe.

2. The coal in-situ controllable direct combustion energy extraction-gasification combined mining method according to claim 1, characterized in that, Along the length of the horizontal well, the coal seam is divided into the combustion zone, the oxygen-enriched combustion zone, the oxygen-deficient gasification zone, the reduction zone, and the dry distillation zone. The oxygen release section is located in the oxygen-enriched combustion zone to release oxidant into the oxygen-enriched combustion zone through the release hole. The gasification product collector moves sequentially in the oxygen-deficient gasification zone, the reduction zone, and the dry distillation zone as the coal seam is mined.

3. The coal in-situ controllable direct combustion energy extraction-gasification combined mining method according to claim 1, characterized in that, The walls of the injection well and the production well are respectively wrapped with thermal insulation material.

4. The coal in-situ controllable direct combustion energy extraction-gasification combined mining method according to claim 1, characterized in that, Tesla pipes are used for the working fluid inlet pipe, working fluid horizontal pipe, working fluid outlet pipe, and gasification product collection pipe.

5. The coal in-situ controllable direct combustion energy extraction-gasification combined mining method according to claim 1, characterized in that, Multiple horizontal wells are drilled in the coal seam; the working fluid horizontal pipes of the multiple horizontal wells are connected and share a working fluid inlet pipe and a working fluid outlet pipe.

6. The coal in-situ controllable direct combustion energy extraction-gasification combined mining method according to claim 1, characterized in that, Multiple horizontal working fluid branch pipes are installed on the horizontal working fluid pipe according to a preset angle.

7. The method for in-situ controlled direct combustion energy extraction and gasification combined mining of coal according to claim 1, characterized in that, During coal seam combustion and the period when the temperature of the thermal reservoir remains above 100℃ in the later stage, the working fluid is CO2 or supercritical CO2. After the coal seam is burned and the residual heat is extracted, the artificial thermal reservoir formed is circulated with water as the working fluid when the temperature reaches 100°C.

8. A coal in-situ controllable direct combustion energy extraction-gasification combined mining system, characterized in that, The coal in-situ controlled direct combustion energy extraction-gasification combined mining method according to any one of claims 1-7 is used for in-situ coal mining. The system includes: a gas supply unit, a heat exchange unit, a data acquisition unit, and a gas supply regulation equipment. The gas supply unit is connected to the gas inlet pipe installed in the injection well to provide oxidant or inert gas for coal seam combustion; wherein, the end of the gas inlet pipe that extends into the horizontal well is equipped with a directional drilling bit, and multiple release holes are provided near the directional drilling bit; The heat exchange unit includes a heat exchanger, a working fluid inlet pipe, a working fluid horizontal pipe, and a working fluid outlet pipe. One end of the working fluid inlet pipe is connected to the heat exchanger or a turbine, and the other end extends into the injection well and connects to one end of the working fluid horizontal pipe. An ignition heating device is fitted at the smooth arc connection between the working fluid inlet pipe and the working fluid horizontal pipe. A gasification product collector is also arranged around the working fluid horizontal pipe. The gasification product collector is located in the horizontal well at a predetermined distance from the end of the inlet pipe in the forward direction. The other end of the working fluid horizontal pipe is connected to the working fluid outlet pipe, and the other end of the working fluid outlet pipe is connected to the heat exchanger or a turbine. The acquisition unit includes a gas chromatograph, which is connected to a gasification product collector via a gasification product collection tube. After analyzing the gas products flowing out of the gasification product collection tube, the gas chromatograph feeds back the gas composition information to the gas supply control equipment, which then controls the amount of oxidant supplied by the gas supply unit to the inlet pipe.

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