Physical simulation device and method for underground coal gasification considering stress direction

Abstract

The present application belongs to the technical field of coal underground gasification simulation experiment, and discloses a coal underground gasification physical simulation device and method considering stress direction, which comprises a support frame, a high-temperature-resistant simulation bin movably arranged on the support frame; the high-temperature-resistant simulation bin is movably arranged on the simulation bin body of the support frame, the coal sample is filled in the simulation bin body, and the side wall of the simulation bin body is provided with a horizontal pressure assembly for horizontally pressurizing the coal sample; the top end of the simulation bin body is sealingly provided with a simulation bin top cover, the simulation bin top cover is provided with a vertical pressure assembly for vertically pressurizing the coal sample; and the bottom end of the simulation bin body is provided with a plurality of auxiliary assemblies for assisting the simulation experiment. The present application has simple structure, can artificially simulate and control the gasification process of the coal sample in the ground, explore the gasification furnace cavity expansion control factors and technologies under the real stress field conditions, and can provide physical experiment reference and basis for the application of the coal underground gasification project.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal underground gasification simulation experiment, and particularly relates to a coal underground gasification physical simulation device and method considering stress direction. BACKGROUND

[0002] The expansion and stability of the gasification furnace cavity are a key research direction in the field of coal underground gasification, and the industry mainly analyzes the expansion law, scale, influence range and control mechanism of the gasification furnace cavity under the geological condition through physical simulation and numerical simulation.

[0003] The physical simulation can directly show the UCG physical phenomenon and process, and is closer to the engineering situation. However, the current UCG stress field physical simulation only considers the stress size, and is a uniform stress, and no physical simulation device considering the stress field type and horizontal stress direction is seen; meanwhile, the expansion of the UCG gasification furnace cavity is affected by the gasification process and the geological condition, wherein the stress field has an important control action on the seepage of the gasification agent, the thermal-induced fracture expansion and the roof stability. However, the current lacks the physical simulation device and method considering the control action of the stress field type and the horizontal stress direction on the expansion of the UCG gasification furnace cavity.

[0004] Therefore, the present application designs a coal underground gasification physical simulation device and method considering stress direction to solve the above technical problems. SUMMARY

[0005] The purpose of the present application is to provide a coal underground gasification physical simulation device and method considering stress direction, to realize the UCG gasification furnace cavity expansion characteristic research and characterization under the constraint of different stress fields and different horizontal stress directions.

[0006] To achieve the above purpose, the present application provides the following scheme: the present application provides a coal underground gasification physical simulation device considering stress direction, comprising a support frame, a high-temperature-resistant simulation bin movably arranged on the support frame, and the high-temperature-resistant simulation bin is used for carrying out gasification simulation experiment on a coal sample;

[0007] The high-temperature-resistant simulation bin is movably arranged on the simulation bin body of the support frame, the coal sample is filled in the simulation bin body, and a horizontal pressing assembly for horizontally pressing the coal sample is arranged on the side wall of the simulation bin body;

[0008] A simulation bin top cover is sealingly arranged at the top end of the simulation bin body, and a vertical pressing assembly for vertically pressing the coal sample is arranged on the simulation bin top cover;

[0009] A plurality of auxiliary assemblies for assisting the simulation experiment are arranged at the bottom end of the simulation bin body.

[0010] Preferably, the vertical pressure assembly comprises a vertical pressure piston movably arranged on the simulation chamber top cover; the vertical pressure piston extends into the simulation chamber body and vertically presses the top end of the coal sample through a vertical pressure bearing.

[0011] Preferably, the simulation chamber top cover is provided with a vertical pressure container, the top end of the vertical pressure piston extends into the vertical pressure container and sealingly slides in the vertical pressure container, and the vertical pressure container injects silicon oil into the vertical pressure piston through a first silicon oil injection port to pressurize the vertical pressure piston.

[0012] Preferably, the horizontal pressure assembly comprises a plurality of horizontal pressure pistons movably arranged at equal intervals on the side wall of the simulation chamber body, the horizontal pressure pistons extend into the simulation chamber body and are drivingly connected with horizontal pressure bearings, and the horizontal pressure bearings abut against the side wall of the coal sample through tile-shaped pressure applicators to horizontally pressurize the coal sample.

[0013] Preferably, the side wall of the simulation chamber body is provided with a plurality of accommodating grooves matched with the tile-shaped pressure applicators, and the tile-shaped pressure applicators are embedded and stored in the accommodating grooves when not pressurized.

[0014] Preferably, the auxiliary assembly comprises a plurality of temperature measurement holes arranged at the bottom end of the simulation chamber body, and a temperature sensor is installed in each temperature measurement hole to extend into the coal sample to measure the temperature of the coal sample.

[0015] Preferably, the auxiliary assembly comprises an ignition device arranged at the bottom end of the simulation chamber body to complete the ignition process of the coal sample.

[0016] Preferably, the auxiliary assembly comprises a synthetic gas extraction port and a plurality of gasification agent injection ports arranged at the bottom end of the simulation chamber body, and the synthetic gas extraction port and the gasification agent injection ports are in communication with the inner cavity of the simulation chamber body.

[0017] The application also discloses a simulation method of a coal underground gasification physical simulation device considering stress direction, comprising the following steps:

[0018] Cutting a coal sample and placing the coal sample into a tested simulation chamber body;

[0019] Assembling a high-temperature-resistant simulation chamber by assembling the simulation chamber top cover, and detecting the air tightness of the high-temperature-resistant simulation chamber;

[0020] Vertically and horizontally pressurizing the coal sample through the vertical pressure assembly and the horizontal pressure assembly;

[0021] Injecting gasification agents and combustion-supporting agents into the simulation chamber body through the auxiliary assembly, observing the fluid state in the simulation chamber body, igniting after the pressure is stabilized, and monitoring the temperature;

[0022] The temperature of the coal sample is controlled by the auxiliary assembly to control the gasification process of the coal sample, and the progress of the gasification process is monitored until the gasification process ends.

[0023] After the gasification process ends, the auxiliary assembly is used to inject melted wax oil into the simulation bin body, and the wax oil is allowed to solidify;

[0024] After the wax oil solidifies, the stress is released through the horizontal pressure assembly and the vertical pressure assembly, then the simulation bin top cover is removed, the coal sample and the wax mold are taken out, and the wax mold is subjected to CT scanning;

[0025] The high-temperature-resistant simulation bin is cleaned and detected, and after no errors are found, simulation experiments under different stress field and stress direction constraint conditions are carried out;

[0026] The experimental data are sorted out and analyzed, and the experimental results are obtained.

[0027] Preferably, during the gasification process, the temperature evolution characteristics of the temperature sensor are monitored in real time to determine the progress of the gasification process, and when the temperature of the temperature measuring point of the temperature sensor close to the synthetic gas extraction port or close to the edge of the simulation bin body reaches a set value, it is determined that the gasification process reaches the last stage, and the injection of the gasification agent is stopped, and the gasification reaction is allowed to stop by itself.

[0028] Compared with the prior art, the application has the following advantages and technical effects: the application discloses a coal underground gasification physical simulation device and method considering stress direction, the high-temperature-resistant simulation bin is fixed through the support frame to ensure the stability of the experimental process; the side wall of the simulation bin body is provided with a horizontal pressure assembly for horizontal pressure, and the simulation bin top cover at the top end of the simulation bin body is provided with a vertical pressure assembly for vertical pressure, so that the coal sample is subjected to triaxial loading in combination with the horizontal pressure assembly, the state of the coal sample under the stratum can be more truly simulated, the coal underground gasification can be controllably simulated, the auxiliary assembly can control and monitor the gasification process of the coal sample, the process of the coal sample gasification can be artificially controlled, the gasification process of the coal sample under different requirements can be simulated, and specific parameters of the coal sample gasification process can be obtained, thereby providing data support for the study of the coal underground gasification.

[0029] The application has the advantages of simple structure, artificial simulation and control of the gasification process of the coal sample under the stratum, exploration of the expansion control factors and technologies of the gasification furnace cavity under the real stress field conditions, and physical experimental reference and basis provided for the application of the coal underground gasification engineering. BRIEF DESCRIPTION OF DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present application, the illustrative embodiments of the present application and the description thereof are used to explain the present application, and do not constitute an improper limitation on the present application. In the drawings:

[0031] Figure 1 It is a schematic diagram of the whole structure of the simulation warehouse top cover;

[0032] Figure 2 It is a schematic diagram of the whole structure of the simulation warehouse top cover;

[0033] Figure 3 It is a schematic diagram of the whole structure of the simulation warehouse top cover;

[0034] Figure 4 It is a schematic diagram of the whole structure of the simulation warehouse top cover;

[0035] In the figure: 1, support frame; 2, simulation warehouse fixing rod; 3, simulation warehouse fixing bolt; 4, rotating handle; 5, simulation warehouse body; 6, simulation warehouse top cover; 7, top cover handle; 8, sealing bolt; 9, first silicone oil injection inlet; 10, silicone oil; 11, sealing ring; 12, vertical pressure piston; 13, coal sample; 14, horizontal pressure piston; 15, second silicone oil injection inlet; 16, tile-shaped pressure applicator; 17, temperature sensor; 18, ignition device; 19, gasification agent injection inlet; 20, synthetic gas extraction outlet; 21, simulation warehouse fixing threaded hole; 22, horizontal piston pressure device injection inlet switch; 23, thin layer of purple copper ring trap; 24, high-temperature-resistant sealing ring; 25, vertical pressure applicator; 26, vertical pressure bearing shaft; 27, horizontal pressure bearing shaft. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0037] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the present application will be further described in detail below with reference to the drawings and specific embodiments.

[0038] The UCG gasifier mentioned in the background of the present application is a key equipment of the underground coal gasification (UCG) technology.

[0039] The UCG gasifier refers to a device that ignites underground coal in situ and converts coal into combustible gas (such as hydrogen, coal gas, methane gas, etc.) through a series of combustion control means and extracts it to the ground.

[0040] During the gasification process, a gasification agent (such as oxygen, water vapor, etc.) is injected into the underground coal seam, and a chemical reaction occurs with the coal seam to generate combustible gas. These gases are collected through the passage of the gasifier and transported to the ground.

[0041] There are various types of UCG gasifiers, including straight well gasifiers, U-shaped well gasifiers, and parallel structure gasifiers, etc. Among them, the U-shaped well gasifier is more suitable for deep coal underground gasification.

[0042] The U-shaped well gasifier is composed of an injection well and a production well. The injection well uses horizontal well drilling for long distances, and the production well uses a straight well. Both are connected and communicated at the bottom of the well to form a gasification passage.

[0043] U-shaped gasifier construction technology: It is necessary to design a gasifier with reasonable structure to realize stable and controllable gasification process. The main advantage of the U-shaped well gasifier is that the coal coverage of the gasification passage is large, which is conducive to the construction of multiple furnaces, has strong production sustainability, and has great industrialization potential.

[0044] Controllable injection point retreating gasification process (CRIP): This process uses a U-shaped gasifier to achieve controllable combustion by injecting a gasification agent through a coiled tubing from a horizontal well. When the first ignition point position is burned out, a first combustion cavity is formed, and then the injection point is controlled to retreat by a coiled tubing by a distance of one combustion cavity to reach the second injection and combustion point, and so on, to push forward to the vertical section of the horizontal injection well.

[0045] Application: UCG gasifier plays a key role in coal underground gasification technology. This technology omits complex underground tunneling mining equipment, reduces safety problems of coal miners working underground, and reduces investment costs of the coal industry. At the same time, this technology also has environmental advantages, and the generated pollutants are much smaller than ground combustion.

[0046] Challenges: Although the UCG gasifier has many advantages, it still faces some challenges. For example, the geological conditions of deep coal seams are more complex, and the implementation of UCG engineering is more difficult. In addition, key technologies such as the construction of the gasifier and the control of gasification combustion still need further research and testing.

[0047] Reference Figures 1-4 As shown in the figure, the embodiment provides a coal underground gasification physical simulation device considering stress direction, which comprises a support frame 1, a high-temperature-resistant simulation bin movably arranged on the support frame 1, and the high-temperature-resistant simulation bin is used for carrying out gasification simulation experiment on the coal sample 13;

[0048] The high-temperature-resistant simulation bin is movably arranged on the simulation bin body 5 of the support frame 1, the coal sample 13 is filled in the simulation bin body 5, and the side wall of the simulation bin body 5 is provided with a horizontal pressure assembly for pressurizing the coal sample 13 through a horizontal plate;

[0049] The top end of the simulation bin body 5 is provided with a simulation bin top cover 6, and the simulation bin top cover 6 is provided with a vertical pressurizing assembly for vertical pressurizing of the coal sample 13.

[0050] The bottom end of the simulation bin body 5 is provided with a plurality of auxiliary assemblies for assisting in simulation experiment.

[0051] The application discloses a coal underground gasification physical simulation device and method considering stress direction, and the high-temperature-resistant simulation bin is fixed through a support frame 1 to ensure stability during the experiment; the side wall of the simulation bin body 5 is provided with a horizontal pressurizing assembly for horizontal pressurizing, the coal sample 13 is horizontally pressurized, the simulation bin top cover 6 at the top end of the simulation bin body 5 is provided with a vertical pressurizing assembly for vertical pressurizing of the coal sample 13, and then the coal sample 13 is subjected to triaxial loading in combination with the horizontal pressurizing assembly, the state of the coal sample 13 under the stratum can be more truly simulated, the coal underground gasification can be controllably simulated, the gasification process of the coal sample 13 can be controlled and monitored through the auxiliary assembly, the gasification process of the coal sample 13 is artificially controlled, the gasification process of the coal sample 13 under different requirements can be simulated, and specific parameters of the gasification process of the coal sample 13 are obtained, thereby providing data support for the study of the coal underground gasification. The application has the advantages of simple structure, artificial simulation and control of the gasification process of the coal sample 13 under the stratum, exploration of gasification furnace cavity expansion control factors and technologies under a real stress field condition, and physical experiment reference and basis provided for the application of the coal underground gasification engineering.

[0052] In an embodiment of the application, the materials of the simulation bin body 5 and the simulation bin top cover 6 are high-temperature-resistant stainless steel, and the temperature resistance temperature is not less than 1800 DEG C; the simulation bin body 5 is a cylinder, and the inside is hollow as a coal seam bin for placing the coal sample 13.

[0053] In an embodiment of the application, the outer diameter of the simulation bin body 5 is 61 cm, and the height is 50 cm; the hollow coal seam bin has a diameter of 50 cm and a height of 45 cm.

[0054] In an embodiment of the application, the two sides of the simulation bin body 5 are respectively provided with simulation bin fixing rods 2, the simulation bin fixing rods 2 are erected on the support frame 1 through simulation bin fixing bolts 3, and the simulation bin body 5 is conveniently fixed.

[0055] In an embodiment of the application, the two ends of the simulation bin fixing rod 2 are respectively provided with rotary handles 4 for controlling movement of the high-temperature-resistant simulation bin and conveniently lifting the simulation bin body 5.

[0056] In an embodiment of the application, the outer side of the simulation bin top cover 6 is provided with a plurality of top cover handles 7 for conveniently assembling and disassembling the simulation bin top cover 6.

[0057] In an embodiment of the present application, the simulation bin body 5 is provided with a plurality of annularly arranged simulation bin fixing screw holes 21, and the simulation bin top cover 6 is locked and fixed to the simulation bin body 5 by a plurality of sealing bolts 8.

[0058] In an embodiment of the present application, a sealing groove is arranged between the simulation bin top cover 6 and the simulation bin body 5, and a high-temperature-resistant sealing ring 24 is arranged in the sealing groove. The sealing ring 11 has a temperature resistance of not less than 1000 DEG C.

[0059] In an embodiment of the present application, the number of the sealing bolts 8 is preferably 12.

[0060] Further optimization scheme, vertical pressure assembly includes movable set in the simulation bin top cover 6 vertical pressure piston 12, vertical pressure piston 12 into the simulation bin body 5 and through the vertical pressure shaft 26 bearing on the top of the coal sample 13 vertical pressure, simulation bin top cover 6 is provided with vertical pressure container, vertical pressure piston 12 top into the vertical pressure container and with vertical pressure container sealing sliding, vertical pressure container through the first silicon oil injection inlet 9 injection of silicon oil 10 to vertical pressure piston 12 pressure. Simulation bin top cover 6 in addition to its rigid structure, the center of which is configured with a vertical pressure container for applying vertical stress; when working, through the constant speed and constant pressure pump and the first silicon oil injection inlet 9 arranged on the vertical pressure container into the vertical pressure container of high temperature resistant silicon oil 10, through the silicon oil 10 to push the vertical pressure piston 12, vertical pressure piston 12 through the simulation bin top cover 6 and through the vertical pressure shaft 26 on the coal sample 13 pressure, simulate different stress field.

[0061] In an embodiment of the present application, the vertical pressure shaft 26 abuts on the vertical pressure device 25 on the coal sample 13, so that the top of the coal sample 13 is uniformly stressed.

[0062] In an embodiment of the present application, the vertical pressure device 25 is adapted to the inner cavity of the simulation bin body 5, and has a diameter of 50 cm and a thickness of 5 cm.

[0063] In an embodiment of the present application, a sealing ring 11 is arranged between the vertical pressure container and the vertical pressure piston 12, which can avoid the leakage of the silicon oil 10 and ensure the stable transmission of the pressure.

[0064] Further optimization scheme, horizontal pressure assembly includes several equidistantly movable horizontal pressure pistons 14 arranged on the side wall of the simulation bin body 5, the horizontal pressure pistons 14 extend into the simulation bin body 5 and are drivingly connected with horizontal pressure bearing shafts 27, the horizontal pressure bearing shafts 27 abut against the side wall of the coal sample 13 through tile-shaped pressure applicators 16 to perform horizontal pressure. Twelve horizontal piston pressure containers are arranged in the side wall of the simulation bin body 5 for horizontal pressure; the centers of the horizontal piston pressure containers are spaced apart by 1 / 12 of the circumference in the side wall of the simulation bin body 5; during operation, high-temperature-resistant silicone oil 10 is pumped into the horizontal piston pressure containers through a constant-speed constant-pressure pump and second silicone oil injection ports 15 arranged on the horizontal piston pressure containers, the horizontal pressure pistons 14 are pushed by the silicone oil 10, the horizontal pressure pistons 14 pass through the simulation bin body 5 and press the coal sample 13 through the horizontal pressure bearing shafts 27 to simulate different stress fields; twelve split tile-shaped pressure applicators 16 are arranged between the inner wall of the simulation bin body 5 and the coal sample 13, the corresponding arc of a single tile-shaped pressure applicator 16 is 1 / 12 of the circumference; the center of the tile-shaped pressure applicator 16 is connected with the corresponding horizontal pressure bearing shaft 27, the bottom end of the tile-shaped pressure applicator 16 is in contact with the bottom of the simulation bin body 5, and high-temperature-resistant lubricating oil is applied between the two during use.

[0065] In an embodiment of the present application, the height of the tile-shaped pressure applicator 16 is 44.95 cm, and the thickness is 0.5 cm.

[0066] In an embodiment of the present application, the side wall of the simulation bin body 5 is provided with a plurality of horizontal piston pressure device injection port switches 22 corresponding to the horizontal pressure pistons 14, so as to control the horizontal pressure of the corresponding positions.

[0067] In an embodiment of the present application, when the horizontal pressure pistons 14 perform horizontal pressure, two diagonal ones are taken as a group of horizontal stress exerting groups to avoid damaging the coal sample 13.

[0068] In an embodiment of the present application, the size and direction of the horizontal stress are controlled by controlling the pressure pumped by the constant-pressure pump; the pressure range of the constant-speed constant-pressure pump is 0-50 MPa, and the control accuracy is ±0.01 MPa.

[0069] Further optimization scheme, the side wall of the simulation bin body 5 is provided with a plurality of accommodating grooves matched with the tile-shaped pressure applicators 16, the tile-shaped pressure applicators 16 are embedded in the accommodating grooves when not exerting pressure. The horizontal pressure bearing shafts 27 are connected with the horizontal pressure pistons 14, and are integrally installed in the accommodating grooves embedded in the inner wall of the simulation bin body 5, so as to avoid affecting the entry and exit of the coal sample 13 when no horizontal pressure is exerted.

[0070] Further optimization scheme, auxiliary assembly includes several temperature measurement hole set in the bottom end of the simulation warehouse body 5, temperature sensor 17 is installed in the temperature measurement hole, temperature sensor 17 extends into coal sample 13 to measure the temperature of coal sample 13; The auxiliary assembly includes an ignition device 18 arranged at the bottom end of the simulation warehouse body 5, which completes the ignition process of the coal sample 13; The auxiliary assembly includes a synthetic gas extraction port 20 and a plurality of gasification agent injection ports 19 arranged at the bottom end of the simulation warehouse body 5, and the synthetic gas extraction port 20 and the gasification agent injection port 19 are communicated with the inner cavity of the simulation warehouse body 5. The bottom of the simulation warehouse body 5 is equipped with 20 temperature sensor mounting holes, 1 ignition device mounting port, 1 synthetic gas extraction port 20 and 5 gasification agent injection ports 19, the temperature sensor mounting hole is used for inserting the temperature sensor 17 into the coal sample 13, so as to monitor the temperature of the coal sample 13 in the UCG process, and the gasification process is judged by the temperature evolution characteristics; The ignition device 18 is installed in the temperature sensor mounting hole, which is used for completing the ignition process of the underground coal gasification; The gasification agent injection port 19 is used for injecting the initial gasification agent and the combustion-supporting agent and controlling the subsequent gasification process; The synthetic gas extraction port 20 is used for extracting synthetic gas and extracting the cavity morphology of the gasification furnace in the later period.

[0071] In an embodiment of the present application, the temperature sensor 17 measures a range of 0-1500℃, with an accuracy of ±0.1℃.

[0072] The present application also discloses a simulation method of a coal underground gasification physical simulation device considering stress direction, comprising the following steps:

[0073] Cutting out the coal sample 13 and placing the coal sample 13 into the tested simulation warehouse body 5;

[0074] Assembling the simulation warehouse top cover 6 to form a high-temperature-resistant simulation warehouse and detecting the air tightness of the high-temperature-resistant simulation warehouse;

[0075] Vertically and horizontally pressurizing the coal sample 13 through the vertical and horizontal pressurizing assemblies;

[0076] Injecting the gasification agent and the combustion-supporting agent into the simulation warehouse body 5 through the auxiliary assembly, observing the fluid state in the simulation warehouse body 5, igniting after the pressure is stable, and monitoring the temperature;

[0077] Controlling the gasification process of the coal sample 13 by controlling the temperature of the coal sample 13 through the auxiliary assembly, monitoring the progress of the gasification process, and stopping until the gasification process is completed;

[0078] After the gasification process is completed, injecting the melted wax oil into the simulation warehouse body 5 through the auxiliary assembly, and waiting for the wax oil to solidify;

[0079] After the wax oil solidifies, releasing the stress through the horizontal and vertical pressurizing assemblies, then removing the simulation warehouse top cover 6, taking out the coal sample 13 and the wax mold, and performing CT scanning on the wax mold;

[0080] Clean and detect high-temperature simulation bin, check no error, and perform simulation experiments under different stress field and stress direction constraint conditions;

[0081] Organize experimental data and analyze to obtain experimental results.

[0082] The experimental process is as follows:

[0083] Step one: select raw coal with complete structure and less fracture development, use a wire cutting instrument to prepare a columnar sample with a diameter of 50 cm and a height of 45 cm vertically, and polish it flat and smooth to form a coal sample 13;

[0084] Step two: wrap the coal sample 13 with a thin layer of copper ring 23 with a thickness of 0.5 mm, and place the coal sample 13 in the coal seam bin with the help of the external hoisting device;

[0085] Step three: install the vertical pressure assembly and the simulation bin top cover 6 in turn, and connect and fix the simulation bin top cover 6 and the simulation bin body 5 through the fixing bolts;

[0086] Step four: inject nitrogen into the simulation bin body 5 and perform airtightness check;

[0087] Step five: after the airtightness check is completed, connect the vacuum pump to extract the gas in the simulation bin;

[0088] Step six: according to the experimental design, use a constant speed and pressure pump to pump high-temperature silicon oil 10 into the vertical pressure container and the horizontal pressure container at the same time, and control the vertical stress and the horizontal stress by setting the target pressure of the constant speed and pressure pump; Note: when loading the horizontal stress, the target pressure of the constant speed and pressure pump should be the minimum horizontal principal stress, and when the vertical stress and the horizontal stress are fully loaded, close the piston injection port valve, and wait for the stress to stabilize; Then according to the maximum horizontal principal stress and direction of the experimental design, open the horizontal piston pressure unit group (the two diagonal piston pressure units correspond to one group) injection port valve that needs to continue to load stress, and set the constant speed and pressure pump pressure to inject high-temperature silicon oil 10 into it to increase the stress in that direction;

[0089] Step seven: after the stress is loaded, inject the gasification agent and the combustion-supporting agent into the high-temperature simulation bin through the external gasification agent injection device, observe the fluid pressure in the high-temperature simulation bin through the pressure gauge, and prepare for ignition and temperature monitoring after the pressure stabilizes;

[0090] Step eight: ignite through the ignition port by the external ignition device 18, and judge whether the ignition is successful by monitoring the temperature array characteristics;

[0091] Step nine: after the ignition is completed, the coal gasification process is controlled by the different gasification agent injection port 19, and the synthesis gas is extracted through the synthesis gas extraction port 20; during the experiment, the temperature array evolution characteristics are monitored in real time to determine the gasification process, when the temperature of the temperature measuring point close to the synthesis gas extraction port 20 or close to the edge of the high-temperature-resistant simulation bin reaches 1000 DEG C, it is determined that the gasification process reaches the last stage, and the gasification agent is stopped, and if the gasification reaction does not end after a period of time, nitrogen should be injected to artificially intervene to stop the gasification process;

[0092] Step ten: after the gasification process is stopped, the high-temperature-resistant simulation bin and the coal sample 13 are cooled to room temperature, and then the melted wax oil is injected into the high-temperature-resistant simulation bin through the synthesis gas extraction port 20 by means of the external wax oil injection device, so as to realize the extraction of the gasification furnace cavity shape characteristics, and after the injection is completed, the wax oil is solidified;

[0093] Step eleven: after the wax oil is completely solidified, the vertical and horizontal stresses are released, and after the stress release is completed, the high-temperature-resistant simulation bin is opened to take out the coal sample 13, and the solidified and shaped furnace cavity wax mold is marked in the direction, and the CT scanning device is used to quantitatively represent the shape characteristics of the wax mold;

[0094] Step twelve: clean and check the experimental device, check no error, according to the experimental scheme, design different stress field and stress direction constraint condition, repeat step one to twelve;

[0095] Step thirteen: arrange the experimental data and process and analyze, explore the furnace cavity expansion law and its control mechanism in the coal carbon underground gasification process under the constraint of different stress field and stress direction.

[0096] In the description of the present application, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore it cannot be understood as a limitation on the present application.

[0097] The above-described embodiments are only preferred modes of the present application, and do not limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. A physical simulation method of underground coal gasification considering stress direction, characterized in that, The method comprises the following steps: cutting out a coal sample (13) and placing the coal sample (13) into a tested simulation bin body (5); assembling a simulation bin top cover (6) to form a high-temperature-resistant simulation bin and testing the air tightness of the high-temperature-resistant simulation bin; vertically and horizontally pressurizing the coal sample (13) through a vertical pressurizing assembly and a horizontal pressurizing assembly; injecting gasification agents and combustion-supporting agents into the simulation bin body (5) through an auxiliary assembly, observing the fluid state in the simulation bin body (5), igniting after the pressure is stabilized, and monitoring the temperature; controlling the temperature of the coal sample (13) through the auxiliary assembly to control the gasification process of the coal sample (13), monitoring the progress of the gasification process, and stopping until the gasification process is completed; after the gasification process is completed, injecting melted wax oil into the simulation bin body (5) through the auxiliary assembly, and waiting for the wax oil to solidify; after the wax oil solidifies, releasing stress through the horizontal pressurizing assembly and the vertical pressurizing assembly, then removing the simulation bin top cover (6), taking out the coal sample (13) and the wax mold, and performing CT scanning on the wax mold; cleaning and testing the high-temperature-resistant simulation bin, checking for no errors, and then performing simulation experiments under different stress field and stress direction constraint conditions; sorting and analyzing experimental data to obtain experimental results; The stress direction considering coal underground gasification physical simulation device used in the stress direction considering coal underground gasification physical simulation method comprises a support frame (1), and a high-temperature-resistant simulation bin movably arranged on the support frame (1), which is used for performing gasification simulation experiments on a coal sample (13); The high-temperature-resistant simulation bin comprises a simulation bin body (5) movably arranged on the support frame (1), wherein the coal sample (13) is filled in the simulation bin body (5), and a horizontal pressurizing assembly for horizontally pressurizing the coal sample (13) is arranged on the side wall of the simulation bin body (5); A simulation bin top cover (6) is sealingly arranged at the top end of the simulation bin body (5), and a vertical pressurizing assembly for vertically pressurizing the coal sample (13) is arranged on the simulation bin top cover (6); A plurality of auxiliary assemblies for assisting in simulation experiments are arranged at the bottom end of the simulation bin body (5); The auxiliary assemblies comprise a plurality of temperature measuring holes arranged at the bottom end of the simulation bin body (5), wherein a temperature sensor (17) is arranged in each temperature measuring hole and extends into the coal sample (13) to measure the temperature of the coal sample (13); The auxiliary assemblies comprise a synthetic gas extraction port (20) and a plurality of gasification agent injection ports (19) arranged at the bottom end of the simulation bin body (5); During the gasification process, the temperature evolution characteristics of the temperature sensor (17) are monitored in real time to determine the progress of the gasification process, and when the temperature of the temperature measuring point of the temperature sensor (17) near the synthetic gas extraction port (20) or near the edge of the simulation bin body (5) reaches a set value, it is determined that the gasification process has reached the last stage, and the injection of the gasification agent is stopped, and the gasification reaction is allowed to stop by itself.

2. The stress orientation considering physical simulation method of coal underground gasification according to claim 1, characterized in that: The vertical pressure assembly comprises a vertical pressure piston (12) movably arranged on the simulation bin top cover (6); the vertical pressure piston (12) extends into the simulation bin body (5) and vertically presses the top end of the coal sample (13) through a vertical bearing shaft (26).

3. The stress orientation considering physical simulation method of coal underground gasification according to claim 2, characterized in that: The simulation bin top cover (6) is provided with a vertical pressure container, the top end of the vertical pressure piston (12) extends into the vertical pressure container and sealingly slides in the vertical pressure container, and the vertical pressure container injects silicon oil (10) into the vertical pressure piston (12) through a first silicon oil injection port (9) to apply pressure.

4. The stress orientation consideration method for physical simulation of underground coal gasification according to claim 1, characterized in that: The horizontal pressure assembly comprises a plurality of horizontal pressure pistons (14) movably arranged at equal intervals on the side wall of the simulation bin body (5), the horizontal pressure pistons (14) extend into the simulation bin body (5) and are drivingly connected with horizontal bearing shafts (27), and the horizontal bearing shafts (27) abut against the side wall of the coal sample (13) through tile-shaped pressure applicators (16) to apply horizontal pressure.

5. The stress orientation considering physical simulation method of coal underground gasification according to claim 4, characterized in that: The side wall of the simulation bin body (5) is provided with a plurality of accommodating grooves matched with the tile-shaped pressure applicators (16), and the tile-shaped pressure applicators (16) are embedded and stored in the accommodating grooves when not applying pressure.

6. The stress orientation considered coal underground gasification physical modeling method according to claim 1, characterized in that: The auxiliary assembly comprises an ignition device (18) arranged at the bottom end of the simulation bin body (5) to complete the ignition process of the coal sample (13).

7. The stress orientation considered coal underground gasification physical modeling method according to claim 1, characterized in that: The synthetic gas extraction port (20) and the gasification agent injection port (19) are communicated with the inner cavity of the simulation bin body (5).

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