61 results about "Underground coal gasification" patented technology

The invention discloses a coal seam group occurrence three-area linkage gas extraction method. Firstly, a coal seam is divided into an underground coal gasification area, a pressure relief permeability increasing area and an original extraction area; in the initial stage of underground coal gasification, in the process that high-temperature combustible gas generated by underground coal gasification is injected into a ground drilling well, the high-temperature combustible gas and a coal body are subjected to heat transfer, so that the temperature of the coal body is increased, and gas desorption is enhanced; under the continuous coupling action of high temperature and high pressure of the high-temperature combustible gas, the permeability of the coal body is improved; in the process that high-temperature combustible gas is injected into the ground drilling well, gas extraction is continuously conducted on other adjacent drilling holes; under the condition that gas injection and gas extraction are sequentially and circularly performed in ground drilling, the coal body is circularly impacted by positive pressure-negative pressure alternating aerodynamic force, and further fracturing of the coal body is facilitated; under the triple effects of high-temperature coal body gas desorption strengthening, coal body permeability increasing and gas displacement, large-flow and high-quality extraction of deep coal seam gas is finally achieved.

The invention discloses a numerical simulation method and system for a coal underground gasification process, and belongs to the technical field of energy development. The method comprises the following steps: constructing a gasification cavity, cavity wall and raw coal three-area conceptual model; establishing a kinetic model coupled with five types of chemical reactions (complete oxidation, water vapor conversion, Boudouard reaction, hydrogenization and water-gas shift), and associating porosity change and cavity wall temperature gradient distribution; dynamic evolution prediction of the semi-teardrop-shaped gasification cavity is realized through a numerical flow of cyclically updating the porosity, marking the cavity, calculating the reaction and outputting the synthesis gas; a cavity form and synthesis gas component curve is generated based on a multi-module system (data preparation, numerical calculation, result analysis and visualization). The problem that the gasification cavity evolution simulation precision is insufficient in the prior art is solved, and the method is suitable for UCG engineering design and safety evaluation.

This invention discloses an underground ignition tool and its operating method for underground coal gasification processes, comprising: a casing with a tool connector inside; an oxygen injection tool connected to the tool connector inside the casing, the oxygen injection tool having a water channel and an oxygen interface; a connector shell fixedly fitted onto the outer side of the tool connector; a hydraulic piston movably disposed within the inner cavity of the connector shell; a separation shell detachably connected to the bottom of the inner wall of the connector shell; and an oxygen pressure piston movably engaged within the inner cavity of the separation shell. This underground ignition tool and its operating method for underground coal gasification processes perfectly solve the technical problem of underground gasifiers being unable to operate continuously and requiring shutdown and closure, while also possessing significant advantages such as simple operation and convenient installation.

This application discloses an in-situ permeability testing system for underground coal gasification, including a core holder comprising a cylinder, a seepage ring, an axial pressure loading component, a gas pipeline, a sealing assembly, a confining pressure sleeve, a core heating element, a temperature and flow rate measurement assembly, an inlet gas pressure measurement assembly, an outlet gas pressure measurement assembly, and a permeability calculation assembly. The system can calculate the permeability of the core using the core holder outlet temperature, outlet flow rate, inlet gas pressure, and outlet gas pressure, combined with the core's dimensional parameters and the gas viscosity at the core holder outlet temperature. This system can simulate the high-temperature, high-pressure, and high-stress environment of deep underground coal gasification and directly perform in-situ core permeability testing, better ensuring the accuracy and reliability of the test results. This application also discloses an in-situ permeability testing method for underground coal gasification.

The invention provides an underground coal gasification ignition device and method, relates to the technical field of underground coal gasification, and aims to improve the ignition success rate and the ignition reliability. The underground coal gasification ignition device comprises a multi-channel continuous pipe, a combustor, a first release sub and an ignition structure which are connected in sequence. A fuel injection channel and an oxygen injection channel are arranged in the multi-channel continuous pipe and the combustor, a nozzle is arranged in the combustor, and the fuel injection channel and the oxygen injection channel are both communicated with the nozzle. A first connecting piece is arranged between the first releasing sub and a shell of the ignition structure in a penetrating mode, and when the load borne by the first connecting piece is larger than a first preset load, the first connecting piece is broken, so that the first releasing sub is separated from the ignition structure. A spraying hole facing the nozzle is formed in a shell of the ignition structure, ignition equipment and a grain are arranged in the shell of the ignition structure, after the first connecting piece is broken, the ignition equipment ignites the grain to form ignition flames, the ignition flames are sprayed out from the spraying hole, fuel is ignited, and then the coal seam is ignited.

The application discloses a numerical simulation method and system for a coal underground gasification process and belongs to the technical field of energy development. The method comprises the following steps: constructing a conceptual model of a gasification cavity, a cavity wall and a raw coal three-zone; establishing a kinetic model coupled with five types of chemical reactions (complete oxidation, steam conversion, Boudouard reaction, hydrogen gasification and water gas shift); correlating the porosity change and the cavity wall temperature gradient distribution; realizing the dynamic evolution prediction of a semi-teardrop-shaped gasification cavity through a numerical process of cyclically updating the porosity, marking the cavity, calculating the reaction and outputting the synthesis gas; and generating the cavity shape and the synthesis gas component curve based on a multi-module system (data preparation, numerical calculation, result analysis and visualization). The application solves the problem of insufficient simulation precision of the gasification cavity evolution in the prior art and is suitable for UCG engineering design and safety evaluation.

The invention relates to the technical field of underground coal gasification gas purification, in particular to an efficient gas filtering device for an underground coal gasification curve type production well, which comprises a conveying channel, a gas inlet channel, a gas outlet channel and a gas outlet channel, the first bend is used for connecting the inlet channel and the connecting channel, and a plurality of first spiral ribs which are spirally arranged are arranged in the first bend; the second bend is used for connecting the connecting channel and the discharging channel, and a plurality of second spiral ribs which are spirally arranged are arranged in the second bend; according to the fine filtration unit, the separation efficiency can be improved by utilizing the characteristics of a curve flow field, large impurities are subjected to pre-separation treatment through centrifugal force generated by airflow steering, the service cycle and the service life of the fine filtration unit can be prolonged, the cleaning frequency can be reduced, and the blocking cycle can be prolonged.

The utility model relates to the field of gas-water separation, in particular to a gas-water separation system for underground coal gasification. Comprising a product well, a synthesis gas washing assembly communicated with a gas outlet of the product well, a gas-water separation treatment assembly communicated with a liquid outlet of the synthesis gas washing assembly, a torch device communicated with a gas outlet of the gas-water separation treatment assembly, and a storage tank assembly communicated with a liquid outlet of the gas-water separation treatment assembly. According to the utility model, the combustible waste gas released in the gas-water separation process is safely combusted by using the torch device, so that atmospheric pollution caused by direct emission of the combustible waste gas is avoided; acid gas, phenols and ammonia nitrogen in the coal gas water are deeply removed through the phenol and ammonia recovery assembly, resource recovery of phenolic substances and liquid ammonia is achieved, meanwhile, purified wastewater can be reused for a chilling water circulating pump and conveyed to a product well or discharged after reaching the standard, the cyclic utilization rate of water resources is greatly increased, and the energy consumption is reduced. Therefore, the fresh water consumption and the wastewater treatment cost are obviously reduced.

The invention discloses a plasma-driven underground gasified coal gas coupling green hydrogen methanation system and method. The system comprises an underground coal gasification subsystem used for generating crude synthesis gas in situ; the high-temperature solid oxide water electrolysis hydrogen and oxygen production subsystem is used for producing hydrogen and oxygen by using green electricity; the gas purification and proportioning subsystem is used for purifying the crude synthesis gas and mixing the crude synthesis gas with hydrogen in proportion; the heat self-sustaining methanation reaction subsystem is used for converting the mixed gas into synthesis gas mainly containing methane under the action of plasma excitation and a catalyst and realizing self-heating operation through built-in heat exchange and waste heat recovery; the natural gas post-processing and conveying subsystem is used for purifying to obtain pipeline-level natural gas; and a waste heat recovery and process control subsystem. The method realizes deep coupling of in-situ conversion of coal resources, flexible regulation and control of green hydrogen and process enhanced methanation, and has the advantages of high energy utilization rate, strong capability of adapting to fluctuating working conditions and low carbon emission.

The present application relates to the field of coal underground gasification analysis, and relates to a simulation analysis method for heat transfer behavior of coal underground gasification under the condition of multiple thin coal seams. The present application divides the grid of each geological layer by the thickness of each geological layer in the target gasification coal seam and its overburden, initializes each parameter of each unit, analyzes the exothermic competition weight based on the endothermic and exothermic reaction rate of the target gasification coal seam, and further determines the net reaction heat source term, updates the temperature of the grid unit based on the net reaction heat source term of each unit, identifies the endothermic and exothermic alternating zone and locates the heat spot center in combination with the exothermic competition weight; the trajectory curvature and heat spot moving speed are obtained based on the associated heat spot center of adjacent time points, and the gasification stability is evaluated; the connected desorption domain is divided based on the overburden temperature, and the desorption window is divided according to the average temperature of the connected desorption domain at each time point, the heat action intensity index and effective desorption volume of each desorption window are calculated, and the basis for analyzing the methane thermal desorption is provided.

The utility model discloses an igniter for coal underground gasification, which comprises a transverse cylinder, a support column is fixed at the bottom edge of the outer side of the transverse cylinder, the bottom position of the support column is attached to the horizontal ground, and the left side position of the transverse cylinder is communicated with an oxygen uptake box; one end of the oxygen uptake mechanism is connected with the igniter body through an air inlet pipe, and the bottom of the igniter body extends into the drilling position. An injection mechanism is further arranged at the top of the transverse cylinder, and a vertical pipe of the injection mechanism is embedded into the outer end of the fuel tank. According to the igniter for underground coal gasification, the oxygen uptake mechanism is arranged, gas can be absorbed through a through hole formed in one side of an oxygen uptake box through the oxygen uptake mechanism, the gas is conveyed to the output end of the igniter body through a gas inlet pipe, efficient ignition treatment can be facilitated through gas conveying, and the gas is conveyed to a combustion position through a nozzle; ignition treatment can be carried out more easily through ignition treatment of the through holes.

This invention discloses a simulation method for the automatic expansion of the combustion chamber in underground coal gasification, relating to the fields of coal mining and numerical simulation technology. The method first constructs an initial reference model and converts it into a steeply dipping strata model using parameter-driven coordinate mapping technology. Subsequently, a parameterized volumetric moving heat source model associated with the coordinate mapping is constructed, with its trajectory dynamically and adaptively positioned according to the dip angle. Further, an update algorithm for rock parameters with nonlinear temperature changes is established, and a heterogeneous field is introduced. Finally, a thermo-mechanical interleaved sequential coupling calculation is performed. In the heat conduction sub-loop, the mesh is dynamically reconstructed based on a temperature threshold to generate cavities, and a mechanical equilibrium sub-loop is triggered to perform stress redistribution calculations when the advance distance threshold is reached. This invention, by coordinating the time scale differences between thermo-mechanical calculations, achieves the simulation of the dynamic evolution of cavities and the asymmetric shear slip failure mechanism of steeply dipping overburden, balancing computational efficiency and result reliability.

The invention discloses an underground coal gasification ash layer stripping device, and relates to the technical field of underground coal gasification ash layer stripping. The execution unit comprises a fixing disc, a gun barrel, a propelling assembly and a stripping assembly. According to the device, the transmission unit is controlled on the ground to drive the gun barrel to rotate, the spray head can rotate in the horizontal plane, and the circumferential cleaning blind area of a channel ash layer is eliminated. And meanwhile, the propelling assembly can control stretching and retracting of the spray head, so that the spray head can adapt to channels with different diameters and keep the optimal spraying distance, and the device can be flexibly attached to irregular channels. Secondly, uniform distribution and stable pressure of a high-pressure medium can be ensured by a flow dividing cavity arranged in the spray head; the spiral flow deflector in each injection pipe converts high-voltage direct flow into high-speed rotational flow to generate strong shear stress, so that a compact ash layer with strong adhesive force is efficiently crushed and stripped.

The application discloses a multi-working mode coordinated exploitation well pattern and an exploitation method thereof, and belongs to the technical field of coal bed gas exploitation. The exploitation well pattern comprises a first horizontal well and a second horizontal well, the first horizontal well and the second horizontal well form a communication channel in a target coal bed, and the communication channel is used for selectively accelerating extraction of coal bed gas or serving as a reaction channel for underground coal gasification; and the exploitation well pattern further comprises a multifunctional well, which is communicated with the communication channel. The application constructs a multi-working mode coordinated exploitation well pattern of "double horizontal wells + multifunctional well", realizes the collection of monitoring production parameters, gas production and extraction, injection of carbon dioxide reaction slurry and solidifying fluid in the multifunctional well, realizes the cooperation of CO2 filling, reinforcement, sealing and storage, and solves the problems of lack of special carbon storage channels and difficulty in multi-technology cooperation in the prior art.

The utility model relates to the technical field of treatment systems for the content of CO and H2 in coal gasification gas, in particular to a post-treatment system for improving the content of CO and H2 in coal gasification gas. According to the technical scheme, the post-treatment system for increasing the content of CO and H2 in the coal gasification gas comprises a high-temperature pure oxygen non-catalytic partial oxidation reaction module, according to the utility model, the non-catalytic partial oxidation reaction equipment and the heat recovery equipment are arranged, so that the process flow of purifying the underground coal gasification product gas is greatly simplified, and the product gas can be subjected to primary purification and heat recovery; the technical process of the product gas purification treatment device matched with the underground coal gasification device is more economical and reasonable, the advantages of reliability and low cost of the underground coal gasification technology are fully played, the problems existing in the existing underground coal gasification technology are solved, CH4 in coal gas is cracked, CO and H2 are generated, and the product gas purification treatment device is more environmentally friendly. And the content of effective components in the coal gas is increased.

The invention provides an underground coal gasification device and an underground coal gasification method, and relates to the technical field of underground coal gasification production. The underground coal gasification device comprises a sleeve and a return operation mechanism. The horizontal section of the well body is located on a coal seam. The well body has an injection end and a production end. The retreating operation mechanism comprises a perforator and a dry distiller which can retreat in the first direction and move synchronously. The perforator is located in the casing pipe and comprises perforating bullets capable of being emitted outwards in the radial direction of the casing pipe so that through holes can be formed in the casing pipe. The dry distiller is located on the side, facing the production end, of the perforator, the dry distiller is provided with a first position located in the coal seam open hole and a second position located in the casing pipe, when the dry distiller is located at the first position, the dry distiller conducts dry distillation modification on the coal seam open hole, and when the dry distiller is located at the second position, the dry distiller corresponds to the through hole. The underground coal gasification device can solve the problems that ignition is difficult due to coal seam water vapor, coal is easy to extinguish during combustion, and the conversion efficiency of raw gas is low.

The invention relates to an anti-collapse treatment method for a coal underground gasification goaf, and the method comprises the steps: carrying out the three-dimensional seismic exploration of a target coal seam region to be subjected to underground gasification, and determining the positions of a fault and a fracture zone of an overlying stratum of a target coal seam; in the underground coal gasification process, the specific range of a goaf is determined through the microseismic technology of regular high-precision three-dimensional earthquakes in combination with real-time monitoring of the temperature difference distribution condition of a coal bed gasification area; designing specific arrangement coordinates, the number and the size of the supporting columns; a positioner and a drill bit are installed at one end of the coiled tubing, the positioner, the drill bit and the coiled tubing are tripped into the goaf of the target coal seam through the gas injection well, and the positioner and the drill bit lead the coiled tubing to be tripped into the preset coordinates of the supporting columns; the other end of the coiled tubing is located at the wellhead of the gas injection well and connected with a concrete pouring device; concrete is input into the goaf from the ground through the coiled tubing, and the supporting columns are poured in a heap mode.

The utility model relates to the field of nozzles, in particular to a supersonic nozzle for underground coal gasification, which comprises a nozzle component and a slag scraping component movably connected onto the nozzle component. The nozzle assembly comprises a nozzle shell movably connected to the slag scraping assembly, a sealing groove formed in the outer surface of the nozzle shell, a second compression section, an expansion section, a narrow throat opening formed in one end of the expansion section and a nozzle outlet formed in the other end of the expansion section, wherein the second compression section and the expansion section are connected to the nozzle shell. The threaded pipe is connected to the nozzle shell, the first compression section is connected to the threaded pipe, and the expansion section is connected with the second compression section. The first compression section, the second compression section and the expansion section are of a double-section compression-expansion structure, so that the gas flow speed is further increased to supersonic speed after the throat reaches the sound speed, the mixing efficiency of a gasifying agent and a coal seam is improved, and the gas tightness in an underground high-pressure environment is ensured through threads on the threaded pipe and a sealing groove.

The invention belongs to the technical field of coal gasification, and discloses an underground coal gasification method and system based on carbon circulation and carbon sequestration, and the underground coal gasification method comprises the following steps: gasifying a gasifying agent rich in carbon dioxide and underground coal, carrying out coal gas alkali washing, regenerating an alkali washing solution, and converting the carbon dioxide into insoluble carbonate to fill an underground gasification combustion area. According to the invention, continuous carbon dioxide can be provided for underground coal gasification, the calorific value or the content of effective components of the produced coal gas can be greatly improved, heat energy resources carried by the coal gas at the gas outlet drilling hole of the underground gasification furnace can be fully utilized, and meanwhile, the emission of carbon dioxide in the coal utilization process is reduced; and the energy-saving and emission-reducing effects are very good.

The invention relates to a fixed self-consuming multifunctional tubular column system and method for underground coal gasification. The fixed self-consuming multifunctional tubular column system comprises a non-target layer tubular column; at least one gasifying agent injection channel and at least one ignition agent conveying channel which are isolated from each other are arranged in the target layer tubular column, and a plurality of functional nodes are distributed at intervals in the axial direction of the target layer tubular column; the multifunctional integrated joint is used for connecting the non-target layer pipe column and the target layer pipe column; the composite cable penetrates through the non-target layer tubular column and the multifunctional integrated connector and is connected with a cable in the target layer tubular column; and the pumping device and the ground control system are connected with the non-target layer pipe column. By means of the innovative design, a brand new solution is provided for the underground coal gasification technology, and good application prospects and market value are achieved.

This invention relates to the field of underground coal gasification simulation technology, and discloses a physical simulation device and method for underground coal gasification based on real rock mass. The device includes a rock mass with a coal chamber and a pressure loading chamber inside. The coal chamber is located above and connected to the pressure loading chamber. Multiple observation windows are provided on the rock mass, and these windows are connected to the coal chamber. The simulation components include a lifting mechanism and a furnace base. The lifting mechanism is located inside the pressure loading chamber, and a coal sample is placed on the furnace base. The lifting mechanism is used to lift the furnace base so that the coal sample extends into the coal chamber. The furnace base seals the coal chamber with a sealing element to form a furnace cavity. An experimental component is set on the furnace base for simulating the gasification of the coal sample within the furnace cavity. This invention enables physical simulation experiments of coal gasification under real rock mass, dynamically monitors the evolution of the gasification cavity, and provides physical experimental reference and basis for applications in medium-deep underground coal gasification projects.

The invention belongs to the technical field of coal underground gasification, and provides a coal underground gasification system and method.The coal underground gasification system comprises a gasification device, a gas compression device, a gas detection device, an oxygen supply device and a controller, and the gasification device is located in a horizontal gasification channel and comprises a pipeline, a high-pressure cavity, a recovery cavity, an electric control nozzle and an ignition plug; the gas compression device is communicated with the left end of the high-pressure cavity, the gas detection device is communicated with the left end of the recovery cavity, the oxygen supply device is communicated with the left end of the pipeline, and the controller is in communication connection with the electric control nozzle, the ignition plug, the gas compression device, the gas detection device and the oxygen supply device. Only one vertical channel and one horizontal gasification channel are needed, the work amount is reduced, the structure is simple, operation is convenient, and the reaction rate can be effectively increased by stripping gray matter through high-pressure gas.

The invention belongs to the technical field of underground coal gasification, and discloses a method and a system for preparing methane-rich coal gas by underground gasification of deep coal. After coal underground gasification enters a normal gasification stage, waste water containing a catalyst is injected into an underground gasification furnace under the conditions of relatively low temperature and high pressure, and the volume percentage content of methane in coal gas is kept to be 35% or above by adjusting the gas-water ratio and / or the position of a gas injection point. The system for realizing the method comprises the underground gasification furnace, the double-layer continuous pipe, the injection device of the double-layer continuous pipe, the variable-frequency water injection pump and the UCG regulation and control unit. The continuous pipe gas inlet is connected with the gasifying agent storage device, and the continuous pipe water inlet is connected with the variable-frequency water injection pump; the underground gasification furnace is connected with the UCG regulation and control unit; the variable-frequency water injection pump is communicated with the catalytic wastewater pool. The stable and necessary process regulation and control method and the operation system for maintaining the production of the methane-rich coal gas from the gasification coal seam are formed, and the methane content in the prepared coal gas is high.

The invention discloses a circulating system for underground coal gasification, and belongs to the technical field of underground coal gasification. A circulating system for underground coal gasification comprises a coal gas output vertical shaft pipe, a conveying pipe communicated with the coal gas output vertical shaft pipe and a cooling system, and a water tank storing water and a power pump communicated with the water in the water tank are arranged at the position of the coal gas output vertical shaft pipe. According to the circulating system for underground coal gasification, water in the water tank is conveyed into the coal gas output vertical shaft pipe through the power pump and the water conveying pipe, the spraying unit can convert the water in the water conveying pipe into fog drops, the fog drops are mixed with coal gas in the coal gas output vertical shaft pipe, and compared with inert gas, the contact area of the fog drops and the coal gas is larger; and the temperature of the coal gas can be quickly and efficiently reduced, so that in the process that the coal gas flows in the coal gas output vertical shaft pipe, the damage of the coal gas with the reduced temperature to the coal gas output vertical shaft pipe is reduced, and the service life of the coal gas output vertical shaft pipe can be prolonged.

The invention discloses a self-expansion type single-channel spiral flow deflector which comprises a flow guide part which is of a continuous spiral sheet structure and can be compressed when pressure is applied to the outer side of the flow guide part; the outer side of the flow guide part is sleeved with a sleeving part, and the sleeving part can limit the compressed flow guide part; through mechanical constraint shaping, elastic recovery expansion of the flow deflectors within 15 seconds is achieved, and interference fit with the casing pipe under the attaching pressure larger than or equal to 3 MPa is formed; by means of the optimized design of shape memory alloy pre-compression, a mechanical constraint release activation mechanism, an interference fit fixing mode with a sleeve, a reserved center cavity with the diameter larger than or equal to 0.5 D, a compatible ignition device with the diameter smaller than or equal to 300 mm, the spiral angle ranging from 25 degrees to 40 degrees and the screw pitch ranging from 0.6 D to 1.0 D, airflow is guided to form a 5-8 m / s rotating flow field, the gas-solid contact time is prolonged by 25%-35%, and the carbon conversion rate is increased by 10%-15%; the yield of synthesis gas (H + CO) is increased by 8-12%; and ash accumulation is inhibited by centrifugal force.

The application discloses a synthesis method of a coal underground gasification catalyst, which comprises the following steps: placing a basic solution and a modified coupling agent in a first evaporation chamber, and heating to generate a first hot solution; spraying the first hot solution into a first reaction chamber, and reacting with alumina placed in the first reaction chamber to obtain a first product; separating the first product by using a cyclone separation device arranged at the tail end of the first reaction chamber to obtain a sample, and placing the sample in a second reaction chamber; placing a silicon oxide precursor, an alumina precursor, a nano calcium carbonate solution, a coupling agent and a curing agent in a second evaporation chamber, and heating to generate a second hot solution; spraying the second hot solution into the second reaction chamber, and reacting with the sample to obtain a second product; and separating the second product by using a cyclone separation device arranged at the tail end of the second reaction chamber to obtain the catalyst. According to the application, the catalyst with improved reaction activity can be synthesized in an environment-friendly way with low cost and easy construction.

The invention relates to the technical field of underground coal gasification, and provides an electric arc-pulse electric heating composite ignition device and method for underground coal gasification, and the device comprises a ground control system and an underground ignition probe; the ground control system provides one of pulse heating current and arc trigger voltage based on temperature parameter self-adaptive adjustment; the underground ignition probe comprises a pulse electric heating element and an arc electrode element, the pulse electric heating element forms a thermal pulse heating field under the action of pulse heating current, and the arc electrode element forms an arc discharge area under the action of arc trigger voltage. Arc transient high-temperature ignition and pulse electric heating steady-state heating are coupled, a transient energy and continuous energy double-field composite ignition mode is formed, local high-temperature cracking of a coal body is achieved within extremely short time, thermal field continuity is maintained through the pulse electric heating effect, the activation degree and the ignition success rate of combustible components of a coal seam are increased, and the ignition efficiency of the coal seam is improved. Meanwhile, the unit energy consumption is reduced.

Disclosed is a method for remining a residual coal pillar in a residual mining area by collaboration of pillar-side backfilling and in-situ gasification. The method includes the following steps of: ascertaining geological and hydrological conditions, a geometric shape and a reserve of a residual coal pillar; carrying out side supporting on the residual coal pillar in a goaf by using a pillar-side backfilling method; and carrying out the underground gasification mining on the residual coal pillar by means of an underground coal gasification process.

The invention discloses a construction method of an underground coal gasification separation wall in-situ grouting water blocking system, and relates to the technical field of underground coal gasification separation. According to the method, a three-dimensional three-level three-layer grouting isolation system is formed through six steps of monitoring deployment, biological barrier construction, initial physical grouting isolation before gasification, chemical grouting barrier construction before gasification, dynamic physical grouting isolation in gasification and final physical grouting isolation after gasification by integrating physical, chemical and biological triple isolation means. Meanwhile, by combining real-time monitoring and cloud intelligent regulation and control, efficient isolation and plugging in the whole process of underground coal gasification are achieved, pollutants are effectively prevented from migrating to pollute underground water, geological stability is guaranteed, and environmental safety guarantee is provided for industrialization of underground coal gasification.