Method and system for determining carbon dioxide perfusion parameters based on goaf three-zone distribution

Abstract

The invention provides a method and a system for determining carbon dioxide perfusion parameters based on goaf three-zone distribution. The method comprises the following steps: acquiring roadway arrangement data of a target coal mine fully-mechanized coal mining face, actual measurement data of the fully-mechanized coal mining face and fully-mechanized coal mining face model parameters; according to the fully mechanized coal mining face model parameters, constructing a goaf numerical simulation model of the fully mechanized coal mining face; inputting the goaf numerical simulation model into COMSOL numerical simulation software, and then simulating and analyzing three-zone distribution data of the goaf under each preset perfusion condition by utilizing the COMSOL numerical simulation software and actual measurement data of the fully mechanized coal mining face; and determining carbon dioxide perfusion parameters of the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset perfusion condition. According to the technical scheme provided by the invention, the optimal carbon dioxide injection process technical parameters can be accurately determined based on quantitative analysis of the three-zone distribution data.

Description

Technical Field

[0001] This application relates to the technical field of gob carbon dioxide perfusion, and particularly to a method and system for determining carbon dioxide perfusion parameters based on the three-zone distribution in the gob. Background Art

[0002] The pores formed by coal spontaneous combustion in the gob and the surrounding rock damage caused by high-temperature roasting will cause surface settlement or even collapse, and produce crisscross pores. Incomplete combustion of coal will also produce various harmful gases, which escape into the ground air through these fissures and seriously pollute the atmospheric environment. The high temperature generated by coal spontaneous combustion continuously bakes the overlying rock, exacerbating the settlement of the surface soil layer, deteriorating the physical and chemical properties of the soil, degrading the surface vegetation, and causing surface water and groundwater to leak deep into the ground, seriously damaging the ecological environment. At the same time, the combustible substances in the gob, such as heat storage, gas, oxygen, and connected fracture networks, are extremely prone to coal spontaneous combustion. The control technology is a series of comprehensive prevention and control methods to prevent coal spontaneous combustion. It usually includes the injection of fire prevention and extinguishing media such as water injection, grouting, inhibitors, inert gases, and liquid inert gases. The porosity determines the action mechanism of the fire prevention and extinguishing media, such as water, slurry, foam, colloid, inert gas, etc. The flowability of the fire prevention and extinguishing media in the porous coal rock mass directly determines its high-temperature treatment effect.

[0003] Currently, the commonly used inert gas, grouting, gel injection, inhibitor and other spontaneous combustion prevention and control technologies at home and abroad each have their applicable conditions and limitations. For example, conventional nitrogen injection measures are difficult to take away heat, nitrogen is easy to diffuse and lose, and a large amount of nitrogen injection is required for fire prevention; when grouting for fire prevention and extinguishing, the grouting system has a large multiple line, the grouting diffusion radius is small, the preventive grouting effect is poor, and it is impossible to achieve large-scale coverage of the gob; the cooling range of gel injection is small, it is difficult to effectively control spontaneous combustion fires, the concealment of coal seam spontaneous combustion is extremely strong, the location of the fire source is vague, and when the location of the fire source cannot be determined, conventional gel injection is difficult to accurately reach the fire source location; injecting liquid nitrogen is easy to freeze in the gob and the cost is relatively high; the inhibitor injection process has high requirements, it is difficult to fully cover the remaining coal, and the inhibition time is short. Through relevant research and tests in recent years, using liquid CO 2 for preventing and extinguishing spontaneous combustion fires in the gob, making full use of its low temperature and inert properties, can quickly and effectively cool down and inert the coal body; CO 2 has a large density, and the gas can stay in the gob for a long time, and the inerting time of the gob is relatively long; at the same time, coal has a strong adsorption capacity for CO 2 and can effectively prevent the contact between O 2 and coal. Therefore, compared with traditional fire prevention and extinguishing technologies, CO 2 fire prevention and extinguishing technology has its own unique advantages. However, in terms of the migration law and fire prevention and extinguishing characteristics of liquid CO 2 in the gob, only a macroscopic analysis of CO 2As for the inerting effect of inert gas on the environment of the fire area, no quantitative research and analysis have been carried out. Therefore, there is an urgent need to propose a quantitative research plan that can determine the optimal carbon dioxide injection process technical parameters based on the migration law, action range, and fire prevention and extinguishing effect after carbon dioxide is injected into the goaf. Summary of the Invention

[0004] The present application provides a method and system for determining carbon dioxide perfusion parameters based on the three-zone distribution in the goaf, so as to at least solve the technical problem that the quantitative research and analysis on the inerting effect of inert gas on the environment of the fire area have not been carried out, making it impossible for the existing technology to determine the optimal carbon dioxide injection process technical parameters based on the migration law, action range, and fire prevention and extinguishing effect after carbon dioxide is injected into the goaf. 2 As for the inerting effect of inert gas on the environment of the fire area, no quantitative research and analysis have been carried out, making it impossible for the existing technology to determine the optimal carbon dioxide injection process technical parameters based on the migration law, action range, and fire prevention and extinguishing effect after carbon dioxide is injected into the goaf.

[0005] The first aspect embodiment of the present application proposes a method for determining carbon dioxide perfusion parameters based on the three-zone distribution in the goaf, and the method includes: Obtain the roadway layout data of the fully mechanized coal mining face of the target coal mine, the measured data of the fully mechanized coal mining face, and the model parameters of the fully mechanized coal mining face; According to the model parameters of the fully mechanized coal mining face, construct a numerical simulation model of the goaf of the fully mechanized coal mining face; Input the numerical simulation model of the goaf into the COMSOL numerical simulation software, and then use the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face to respectively simulate and analyze the three-zone distribution data of the goaf under each preset perfusion condition; Determine the carbon dioxide perfusion parameters of the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset perfusion condition; Among them, the three-zone distribution data includes: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the air inlet side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side.

[0006] Preferably, the roadway layout data of the fully mechanized coal mining face includes: The shape, length, net width, net height, and net cross-sectional area of the belt conveyor roadway, the shape, length, net width, net height, and net cross-sectional area of the return air roadway, the shape, length, net width, net height, and net cross-sectional area of the auxiliary transportation roadway, the shape, length, net width, net height, and net cross-sectional area of the cutting roadway, the shape, length, net width, net height, and net cross-sectional area of the main withdrawal roadway, and the shape, length, net width, net height, and net cross-sectional area of the auxiliary withdrawal roadway; The measured data of the fully mechanized coal mining face includes: The intake air volume of the fully mechanized coal mining face, the air velocity and oxygen concentration at the air inlet of the fully mechanized coal mining face; Each preset perfusion condition includes: The number of preset carbon dioxide injection ports, the positions of the preset carbon dioxide injection ports, the preset carbon dioxide injection flow rates, and the preset air distribution volumes.

[0007] Further, constructing a numerical simulation model of the gob area of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face includes: Constructing a three-dimensional gob numerical model of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face; Using unstructured orthogonal hexahedron meshes to perform mesh division on the three-dimensional gob numerical model to obtain the numerical simulation model of the gob area of the fully mechanized coal mining face.

[0008] Further, a multi-field coupling mathematical model of gob spontaneous combustion is internally coupled in the COMSOL numerical simulation software; Among them, the multi-field coupling mathematical model of gob spontaneous combustion includes: the steady-state porosity distribution characteristic equation of gob coal and rock, the flow field control equation, the material field control equation, and the adsorption condition control equation; The flow field control equation, the material field control equation, and the adsorption condition control equation are set in the Darcy's law module of the COMSOL numerical simulation software.

[0009] Further, the calculation formula of the steady-state porosity distribution characteristic equation of gob coal and rock is as follows:

[0010]

[0011] In the formula, is the swelling coefficient of caving, is the swelling coefficient after compaction, is the swelling coefficient of the lower part of the gob near the working face, is the initial swelling coefficient of caving, is the first adjustment parameter, is the second adjustment parameter, is the decay rate of the swelling coefficient of the caving coal and rock mass with the distance from the solid wall, is the decay rate of the swelling coefficient of the caving coal and rock mass at the working face, is the decay rate from the gob roof, d 0 is the distance from the point (x, y, z) to the gob solid wall, d 1 is the distance from the point (x, y, z) to the working face, d 2 is the distance from the point (x, y, z) to the gob floor boundary, b 0 is the adjustment parameter along the gob depth direction, b 1 is the adjustment parameter along the working face direction, is the porosity distribution function; The calculation formula of the flow field control equation is as follows:

[0012] In the formula, is the fluid pressure, is the local acceleration under unsteady flow conditions, is the viscous stress term describing the shear viscous effect of the fluid, is the permeability, is the internal inertia resistance coefficient, is the density of the mixed gas, is the velocity vector, is the mass source term, is the porosity of coal and rock in the gob area, is the external force vector; The calculation formula of the material field control equation is as follows:

[0013]

[0014] In the formula, is the diffusion flux, is the material concentration, is the reaction rate, is the material source term, is the dispersion coefficient, is the effective diffusion coefficient; The calculation formula of the adsorption condition control equation is as follows:

[0015] In the formula, is the adsorption concentration, is the adsorption condition control equation.

[0016] Furthermore, the three-zone distribution data of the gob area under each preset perfusion condition are respectively simulated and analyzed by using the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face, including: Input the measured data of the fully mechanized coal mining face into the Darcy's law module in the COMSOL numerical simulation software, and then simulate the oxygen concentration distribution cloud map of the gob area under each preset perfusion condition based on the Darcy's law module; Analyze the oxygen concentration distribution cloud map of the gob area under each preset perfusion condition to obtain the three-zone distribution data of the gob area under each preset perfusion condition.

[0017] Furthermore, the carbon dioxide perfusion parameters of the gob area of the target coal mine are determined according to the three-zone distribution data of the gob area under each preset perfusion condition, including: Among the three-zone distribution data of the gob area corresponding to each preset number of carbon dioxide injection ports, screen out the number of carbon dioxide injection ports corresponding to the minimum width of the oxidation heating zone, and use the screened number of carbon dioxide injection ports as the number of carbon dioxide injection ports for the gob area of the target coal mine; Among the three-zone distribution data of the gob area corresponding to each preset position of the carbon dioxide injection port, screen out the position of the carbon dioxide injection port corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened position of the carbon dioxide injection port as the position of the carbon dioxide injection port for the gob area of the target coal mine; Among the three-zone distribution data of the gob area corresponding to each preset carbon dioxide injection flow rate, screen out the carbon dioxide injection flow rate corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened carbon dioxide injection flow rate as the carbon dioxide injection flow rate for the gob area of the target coal mine; Among the three-zone distribution data of the gob area corresponding to each preset air distribution volume, screen out the air distribution volume corresponding to the minimum width of the oxidation heating zone, and use the screened air distribution volume as the air distribution volume for the gob area of the target coal mine.

[0018] An embodiment of the second aspect of the present application provides a carbon dioxide perfusion parameter determination system based on the three-zone distribution of the gob area, including: An acquisition module, configured to acquire roadway layout data of the fully mechanized coal mining face of the target coal mine, measured data of the fully mechanized coal mining face, and model parameters of the fully mechanized coal mining face; A construction module, configured to construct a numerical simulation model of the gob area of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face; A simulation module, configured to input the numerical simulation model of the gob area into COMSOL numerical simulation software, and then use the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face to respectively simulate and analyze the three-zone distribution data of the gob area under each preset perfusion condition; A determination module, configured to determine the carbon dioxide perfusion parameters of the gob area of the target coal mine according to the three-zone distribution data of the gob area under each preset perfusion condition; Wherein, the three-zone distribution data includes: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the intake side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side.

[0019] An embodiment of the third aspect of the present application provides an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the method described in the embodiment of the first aspect is implemented.

[0020] A fourth aspect embodiment of the present application proposes a computer-readable storage medium, on which a computer program is stored, and when the program is executed by a processor, the method described in the embodiment of the first aspect is implemented.

[0021] The technical solutions provided by the embodiments of the present application at least bring the following beneficial effects: The present application proposes a method and system for determining carbon dioxide perfusion parameters based on the three-zone distribution in a gob area. The method includes: obtaining roadway layout data of a target coal mine fully mechanized mining face, measured data of the fully mechanized mining face, and fully mechanized mining face model parameters; constructing a numerical simulation model of the gob area of the fully mechanized mining face according to the fully mechanized mining face model parameters; inputting the numerical simulation model of the gob area into COMSOL numerical simulation software, and then using the COMSOL numerical simulation software and the measured data of the fully mechanized mining face to respectively simulate and analyze the three-zone distribution data of the gob area under each preset perfusion condition; determining the carbon dioxide perfusion parameters of the gob area of the target coal mine according to the three-zone distribution data under each preset perfusion condition; wherein, the three-zone distribution data includes: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the intake side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side. The technical solution proposed by the present application can accurately determine the optimal carbon dioxide injection process technical parameters based on quantitative analysis of the three-zone distribution data.

[0022] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of the embodiments in conjunction with the drawings, where: Figure 1 FIG. is a flowchart of a method for determining carbon dioxide perfusion parameters based on the three-zone distribution in a gob area according to an embodiment of the present application; Figure 2 FIG. is a three-dimensional gob area numerical model according to an embodiment of the present application; Figure 3 FIG. is a numerical simulation model of the gob area of a fully mechanized mining face according to an embodiment of the present application; Figure 4 FIG. is an oxygen concentration distribution map of the Z = 2.7 m plane according to an embodiment of the present application; Figure 5 FIG. is an oxygen concentration distribution map of the Z = 0.2 m plane according to an embodiment of the present application; Figure 6 FIG. is an oxygen concentration distribution contour map under the condition of a single gas injection port according to an embodiment of the present application; Figure 7 It is the oxygen concentration distribution nephogram under the condition of two gas injection ports provided according to an embodiment of the present application; Figure 8 It is the oxygen concentration distribution nephogram under the condition of three gas injection ports provided according to an embodiment of the present application; Figure 9 It is the oxygen concentration distribution nephogram of the injection port at 30 m on the intake side provided according to an embodiment of the present application; Figure 10 It is the oxygen concentration distribution nephogram of the injection port at 50 m on the intake side provided according to an embodiment of the present application; Figure 11 It is the oxygen concentration distribution nephogram of the injection port at 70 m on the intake side provided according to an embodiment of the present application; Figure 12 It is the oxygen concentration distribution nephogram of the gob area when the gas injection flow rate is 0.1 m / s provided according to an embodiment of the present application; Figure 13 It is the oxygen concentration distribution nephogram of the gob area when the gas injection flow rate is 0.3 m / s provided according to an embodiment of the present application; Figure 14 It is the oxygen concentration distribution nephogram of the gob area when the gas injection flow rate is 0.5 m / s provided according to an embodiment of the present application; Figure 15 It is the oxygen concentration distribution nephogram of the gob area when the air distribution volume is 1900 m 3 / min provided according to an embodiment of the present application; Figure 16 It is the oxygen concentration distribution nephogram of the gob area when the air distribution volume is 2500 m 3 / min provided according to an embodiment of the present application; Figure 17 It is the oxygen concentration distribution nephogram of the gob area when the air distribution volume is 3500 m 3 / min provided according to an embodiment of the present application; Figure 18 It is the oxygen concentration distribution diagram of injecting carbon dioxide from the ground into the gob area provided according to an embodiment of the present application; Figure 19 It is the schematic diagram of the change of carbon dioxide concentration at the real-time monitoring points of the 2204 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 20 It is the schematic diagram of the change of temperature at the real-time monitoring points of the 2204 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 21 It is the change of CO concentration at the real-time monitoring points of the 2204 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 22The change of carbon dioxide concentration at the real-time monitoring points in the 4215 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 23 The change of temperature at the real-time monitoring points in the 4215 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 24 The change of CO concentration at the real-time monitoring points in the 4215 fully-mechanized coal mining face provided according to an embodiment of the present application; Figure 25 The structural diagram of a carbon dioxide perfusion parameter determination system based on the three-zone distribution in the goaf provided according to an embodiment of the present application. Detailed implementation manners

[0024] The embodiments of the present application are described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described by referring to the accompanying drawings are exemplary and are intended to explain the present application, but should not be construed as limiting the present application.

[0025] The carbon dioxide perfusion parameter determination method and system based on the three-zone distribution in the goaf proposed by the present application, the method includes: obtaining the roadway layout data of the fully-mechanized coal mining face of the target coal mine, the measured data of the fully-mechanized coal mining face, and the model parameters of the fully-mechanized coal mining face; constructing a numerical simulation model of the goaf of the fully-mechanized coal mining face according to the model parameters of the fully-mechanized coal mining face; inputting the numerical simulation model of the goaf into the COMSOL numerical simulation software, and then respectively simulating and analyzing the three-zone distribution data of the goaf under each preset perfusion condition by using the COMSOL numerical simulation software and the measured data of the fully-mechanized coal mining face; determining the carbon dioxide perfusion parameters of the goaf of the target coal mine according to the three-zone distribution data under each preset perfusion condition; where the three-zone distribution data includes: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the air inlet side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side. The technical solution proposed by the present application can accurately determine the optimal carbon dioxide injection process technical parameters based on the quantitative analysis of the three-zone distribution data.

[0026] The carbon dioxide perfusion parameter determination method and system based on the three-zone distribution in the goaf of the embodiments of the present application are described below with reference to the accompanying drawings.

[0027] Embodiment 1 Figure 1 The flowchart of a carbon dioxide perfusion parameter determination method based on the three-zone distribution in the goaf provided according to an embodiment of the present application, as Figure 1 shown, the method includes: Step 1: Obtain the roadway layout data of the fully mechanized coal mining face of the target coal mine, the measured data of the fully mechanized coal mining face, and the model parameters of the fully mechanized coal mining face; It should be noted that the roadway layout data of the fully mechanized coal mining face includes: The shape, length, net width, net height, and net cross-sectional area of the belt conveyor gateway, the shape, length, net width, net height, and net cross-sectional area of the return airway, the shape, length, net width, net height, and net cross-sectional area of the auxiliary conveyor gateway, the shape, length, net width, net height, and net cross-sectional area of the cutting roadway, the shape, length, net width, net height, and net cross-sectional area of the main withdrawal roadway, and the shape, length, net width, net height, and net cross-sectional area of the auxiliary withdrawal roadway; The measured data of the fully mechanized coal mining face includes: The air intake volume of the fully mechanized coal mining face, the wind speed at the air inlet of the fully mechanized coal mining face, and the oxygen concentration.

[0028] It should be noted that the gob numerical simulation is to build a model according to the actual on-site conditions, and then assign parameters according to the on-site observations, that is, the measured data and the parameters of laboratory research, and calculate and deduce the migration law of the airflow field in the gob. It makes certain idealized assumptions about the internal conditions of the gob, believing that the gob is an ideal homogeneous medium, ignoring the influence of some objective factors such as fissures and geological structures in the gob. However, generally speaking, it can reflect the change law of the airflow in the gob, guide the safety prevention and control of coal mines and the improvement of technical means. Among them, the parameters of the laboratory research include: the critical oxygen concentration of the gob extinguishing zone, the spontaneous combustion characteristic parameters of the residual coal, and the gas components in the gob analyzed by the laboratory chromatograph.

[0029] For example, the roadway layout data of the 4215 fully mechanized coal mining face of a certain coal mine is shown in Table 1.

[0030] Table 1

[0031] Since the belt conveyor gateway and the auxiliary conveyor gateway are on one side of the working face, when establishing the numerical simulation model, in order to save the number of grids and thus reduce the running time during calculation, the two intake airways are combined into one, and the air volume is the sum of the two airways. According to the actual situation of the 4215 working face, a model is established at a ratio of 1:1, and the model parameters of the fully mechanized coal mining face are shown in Table 2.

[0032] Table 2

[0033] Step 2: Construct a gob numerical simulation model of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face; In the embodiment of the present disclosure, Step 2 specifically includes: 2.1 Construct a three-dimensional gob numerical model of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face; 2.2 Use non - structured orthogonal hexahedral meshes to divide the three - dimensional goaf numerical model to obtain the goaf numerical simulation model of the fully - mechanized coal mining face.

[0034] It should be noted that the measured air inflow of the 4215 working face on - site is 1908 m 3 / min, the set air velocity at the air inlet is 1.76 m / s, the oxygen concentration is the oxygen concentration of air, with a volume fraction of 21%, the outlet is set as outflow, and the goaf is set as porous medium for solution. The three - dimensional goaf numerical model as Figure 2 shown is divided into meshes by the physical field control method. The mesh size is set to be coarsened, the number of vertex elements is 30, the number of edge elements is 1648, the number of boundary elements is 47743, the number of elements is 281763, and the minimum element quality is 0.0003694. The mesh division diagram of this model, that is, the goaf numerical simulation model of the fully - mechanized coal mining face, can be obtained, as Figure 3 shown.

[0035] Step 3: Input the goaf numerical simulation model into the COMSOL numerical simulation software, and then use the COMSOL numerical simulation software and the measured data of the fully - mechanized coal mining face to simulate and analyze the three - zone distribution data of the goaf under each preset perfusion condition; It should be noted that the each preset perfusion condition includes: The number of each preset carbon dioxide injection ports, the position of each preset carbon dioxide injection port, the flow rate of each preset carbon dioxide injection, and the air distribution volume of each preset.

[0036] It should be noted that the internal of the COMSOL numerical simulation software is coupled with a multi - field coupling mathematical model for goaf spontaneous combustion; Among them, the multi - field coupling mathematical model for goaf spontaneous combustion includes: the steady - state porosity distribution characteristic equation of coal and rock in the goaf, the flow field control equation, the material field control equation, and the adsorption condition control equation; The flow field control equation, the material field control equation, and the adsorption condition control equation are set in the Darcy's law module of the COMSOL numerical simulation software.

[0037] Furthermore, the calculation formula of the steady - state porosity distribution characteristic equation of coal and rock in the goaf is as follows:

[0038]

[0039] In the formula, is the swelling coefficient of caving, is the swelling coefficient after compaction, is the swelling coefficient at the lower part of the gob near the working face, is the swelling coefficient of the initial caving, is the first adjustment parameter, is the second adjustment parameter, is the decay rate of the swelling coefficient of the caving coal and rock mass with the distance from the solid wall, is the decay rate of the swelling coefficient of the caving coal and rock mass at the working face, is the decay rate with respect to the gob roof distance, d 0 is the distance from the point (x, y, z) to the solid wall of the gob, d 1 is the distance from the point (x, y, z) to the working face, d 2 is the distance from the point (x, y, z) to the floor boundary of the gob, b 0 is the adjustment parameter along the depth direction of the gob, b 1 is the adjustment parameter along the working face direction, is the porosity distribution function; The calculation formula of the above flow field control equation is as follows:

[0040] In the formula, is the fluid pressure, is the local acceleration under unsteady flow conditions, is the viscous stress term describing the fluid shear viscosity effect, is the dynamic viscosity, is the permeability, is the internal inertial resistance coefficient, is the density of the mixed gas, is the velocity vector, is the mass source term, is the porosity of the gob coal and rock, is the external force vector, representing the force exerted on the fluid by the outside world in addition to the above internal actions; The calculation formula of the above substance field control equation is as follows:

[0041]

[0042] In the formula, is the diffusion flux, is the substance concentration, is the reaction rate, is the substance source term, is the dispersion coefficient, is the effective diffusion coefficient; The calculation formula of the above adsorption condition control equation is as follows:

[0043] In the formula, is the adsorption concentration, is the adsorption condition control equation.

[0044] Furthermore, the three-zone distribution data of the gob under each preset perfusion condition are respectively simulated and analyzed by using the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face, including: Input the measured data of the fully mechanized coal mining face into the Darcy's law module in the COMSOL numerical simulation software, and then simulate the oxygen concentration distribution cloud map of the gob under each preset perfusion condition based on the Darcy's law module; Analyze the oxygen concentration distribution cloud map of the gob under each preset perfusion condition to obtain the three-zone distribution data of the gob under each preset perfusion condition.

[0045] Among them, the three-zone distribution data include: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the intake side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side.

[0046] It should be noted that with the help of the COMSOL software, based on the finite element method, the control equations listed in the multi-field coupling mathematical model of goaf spontaneous combustion are discretized by using the implicit backward difference formula method, and finally the MUMPS solver is used to perform unsteady calculations on the carbon dioxide flow and diffusion process inside the goaf to obtain the simulation results.

[0047] It should be noted that according to the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face, the numerical simulation results under each preset perfusion condition are respectively simulated and analyzed, and the planes of Z = 2.7m and Z = 0.2m are selected for analysis. The oxygen concentration distribution law of the Z = 2.7m plane is as Figure 4 shown; From Figure 4 it can be seen that the oxygen concentration on the intake side of the gob drops to 18% at a position about 180m away from the upper corner of the intake side, and drops below 9.2% at a position about 285m away from the upper corner of the intake side; the oxygen concentration on the return air side drops to 18% at the position of the return air corner and drops below 9.2% at a position about 115m away from the return air corner. The simulation results are basically consistent with the measured oxygen concentration distribution data. The oxygen concentration distribution law of the Z = 0.2m plane is as Figure 5 shown.

[0048] From Figure 5It can be seen that on the plane of Z = 0.2 m, the oxygen concentration on the intake side drops to 18% at about 130 m away from the working face and drops to 9.2% at about 230 m away from the intake side of the working face; the oxygen concentration on the return side drops to 18% at about 12 m away from the working face and drops to 9.2% at about 110 m away from the return side of the working face. From this, the width of the oxidation heating zone on the intake side is calculated to be 100 m, and the width of the oxidation heating zone on the return side is 98 m. It can be seen that the risk of spontaneous combustion on the intake side is greater than that on the return side.

[0049] Through the above analysis of the simulation results, the division range of the "three zones" of oxidation in the goaf of the 4215 fully mechanized coal mining face under the simulation conditions can be obtained, as shown in Table 3.

[0050] Table 3

[0051] For example, the 4215 working face adopts the single longwall mining method, the fully mechanized caving mining technology, and the retreating mining method. The goaf roof is managed by the natural caving method, and the ventilation method is two intakes and one return. The dip length of the working face is 3503.3 m, and the strike length is 296.95 m. The advancing distance of the working face is 3503.3 m, the length of the cutting eye is 296.95 m, the coal seam thickness ranges from 2.7 m to 3.9 m (including parting), and the average coal seam thickness is 3.54 m (excluding parting) / 3.66 m (including parting). The designed mining height is 3.7 m. -2 The apparent density of coal is 1.32 t / m 3 . The basic geological reserve of coal in the mining area is 4.8612 million tons. The working face mines -2 coal seam, -2 coal is located at the top of the second section in a certain place. The coal type is mainly non-caking coal, with a small amount of long-flame coal, and it is semi-bright coal. -2 The coal occurrence is relatively stable, the burial depth is 27.5 - 169 m, the coal seam dip angle is 0.6° - 2°, and the average coal seam dip angle is 1.2°. -2 The spontaneous combustion tendency grade of the coal seam is Class I, belonging to an easily spontaneous combustion coal seam, and the spontaneous combustion period is 36 days. The coal dust has explosion risk, and the explosion index is 34.91%. The absolute gas emission volume is 4.41 m 3 / min, the relative gas emission volume is 0.21 m 3 / t, the absolute carbon dioxide emission volume is 10.29 m 3 / min, the relative carbon dioxide emission volume is 0.48 m 3 / t, belonging to a low-gas mine. Three gateways are arranged in the working face, namely the belt conveyor gateway, the auxiliary transportation gateway and the return airway. The specific layout data of the roadways are shown in Table 4; Table 4

[0052] By adjusting the settings of different influencing factors, the influence of different influencing factors on the carbon dioxide injection effect was studied, that is, to determine the influence of each preset injection condition on the carbon dioxide injection effect. Each preset injection condition is shown in Table 5; Table 5

[0053] The analysis of the influence law of the number of carbon dioxide injection ports on the gas migration in the gob area is as follows: Only taking the number of injection ports as the research object, the carbon dioxide injection flow rate is 0.3 m / s, and the position of a single injection port is 50 m from the working face on the intake side. The results obtained through simulation are as Figure 6 shown.

[0054] Under the condition that other preconditions remain unchanged, the number of injection ports is changed to 2, and the positions of the two injection ports are 50 m from the working face on the intake side. The results obtained through simulation are as Figure 7 shown.

[0055] Similarly, with other conditions unchanged, the number of injection ports is adjusted to 3, and the positions of the three injection ports are 50 m from the working face on the intake side. The results obtained through simulation are as Figure 8 shown.

[0056] Through comparative analysis, it can be found that when there is only a single injection port, the closer the position of the injection port is to the working face, the worse the inerting effect of carbon dioxide; while within the reasonable injection port position range obtained by the research, when the number of injection ports changes from 1 to 2 and then increases to 3, the widths of the oxidation zones in the gob area are 180 m, 140 m, and 102 m in sequence, and the widths of the oxidation zones on the return air side are 120 m, 90 m, and 49.5 m respectively. The effect of reducing the oxygen concentration in the gob area is obvious, and the change range of the oxidation zone is relatively obvious. It can be seen from this that increasing the number of injection ports can improve the injection efficiency, more quickly reduce the oxygen concentration in the gob area, and thus effectively prevent coal spontaneous combustion. More specifically, increasing the number of injection ports can accelerate the diffusion rate of carbon dioxide, make carbon dioxide fill the gob area faster, thus more quickly reduce the oxygen concentration, avoid the contact between coal and oxygen, and reduce the risk of spontaneous combustion. In addition, multiple injection ports can improve the uniformity of injection, ensure that every corner of the gob area can be effectively treated, and further enhance the fire extinguishing effect. Therefore, in actual work, select the appropriate number and position of injection ports according to the on-site situation.

[0057] The analysis of the influence law of the position of the carbon dioxide injection port on the gas migration in the gob area is as follows: Controlling the carbon dioxide injection flow rate to be 0.3 m / s, setting the injection port position at 30 m from the working face on the intake side, and injecting carbon dioxide under pressure. The results obtained through simulation are as Figure 9 shown.

[0058] With other conditions remaining unchanged, the gas injection port is set at a position 50 m away from the working face on the intake side, and carbon dioxide is injected. The results obtained through simulation are as Figure 10 shown.

[0059] Controlling the other conditions to be the same as those in the previous two simulations, only changing the position of the carbon dioxide injection point. The gas injection port is set at a position 70 m away from the working face on the intake side, and carbon dioxide injection simulation is carried out. The results obtained are as Figure 11 shown.

[0060] When the burial depth of the carbon dioxide injection port is 30 m, the decline rate of the oxygen concentration on the intake side of the gob is significantly slower. The oxygen concentration drops to 18% at about 35 m and to 9.2% at about 235 m. The oxidation zone ranges from 35 m to 225 m, and the width of the oxidation zone is 195 m, followed by the asphyxiation zone. When the burial depths of the carbon dioxide injection points are 50 m and 70 m, it can be observed that the decline trend of the oxygen concentration on the intake side is significantly accelerated. When the burial depth is 50 m, the width of the oxidation zone on the intake side is about 95 m; when the burial depth is 70 m, after injecting carbon dioxide, the width of the oxidation zone on the intake side is about 40 m. The reason for this situation is that when the carbon dioxide injection port is close to the working face, under the influence of the leakage air flow of the working face, part of the carbon dioxide flows out of the gob quickly along with the leakage air, resulting in a decrease in the utilization rate of carbon dioxide and a poor inerting effect on the gob. When the burial depth of the injection port is large, due to the weakening of the dilution effect of the air flow on carbon dioxide, the diffusion of carbon dioxide to the surrounding is relatively uniform, and the inerting effect is significantly enhanced. However, when the burial depth of the injection point is 70 m at the middle position of the gob, the width of the oxidation zone is significantly wider than that when the burial depth of the injection point is 50 m. The reason for this phenomenon is that the coal and rock in the middle of the gob are gradually compacted in the direction deep into the gob, the porosity decreases, which is not conducive to the diffusion of carbon dioxide, and its inerting effect is weakened.

[0061] Through comparative analysis, it can be seen that when the burial depth of the carbon dioxide injection port is between 50 and 70 m, the inerting effect on the gob is better. If the burial depth of the injection port is too small, a large part of the carbon dioxide will quickly flow back to the working face under the action of the leakage air flow, the utilization rate of carbon dioxide will be reduced a lot, and the inerting effect on the gob will also be reduced accordingly, and it is impossible to shorten the width of the oxidation zone in the gob well; if the burial depth of the injection port is too large, it is impossible to reduce the oxygen concentration of the coal and rock in the compacted part in the middle of the gob well, and the fire prevention and extinguishing effect will be reduced a lot.

[0062] The analysis of the influence law of carbon dioxide injection flow rate on gas migration in the gob is as follows: Controlling the position and quantity of the carbon dioxide injection port unchanged, only changing the injection flow rate of carbon dioxide. That is, the gas injection port is set at a position 50 m away from the working face on the intake side, the number of gas injection ports is 1, and the carbon dioxide injection flow rate is set to 0.1 m / s. The simulation results are asFigure 12 as shown

[0063] With other conditions remaining unchanged, only the carbon dioxide injection flow rate is changed. The simulation results obtained by setting the carbon dioxide injection flow rate to 0.3 m / s are as Figure 13 shown

[0064] With other conditions remaining unchanged, only the carbon dioxide injection flow rate is changed. The simulation results obtained by setting the carbon dioxide injection flow rate to 0.5 m / s are as Figure 14 shown

[0065] Through comparative analysis, it can be found that: when the buried depth of the injection port is certain, the greater the carbon dioxide injection flow rate, under the action of the concentration gradient and pressure, the more obvious the inerting effect of carbon dioxide, and the smaller the range of the oxidation zone in the gob. When the carbon dioxide injection flow rate increases to a certain extent, the range of the oxidation zone in the gob no longer changes significantly, that is, the inerting effect of carbon dioxide weakens at this time. This is because the porosity of the residual coal in the middle of the gob is relatively low, thus inhibiting the diffusion of carbon dioxide. Therefore, in order to obtain a better carbon dioxide diffusion range and ensure the safety of the working face personnel, the injection port needs to be set at a certain distance from the intake airway, and at the same time, a suitable injection flow rate should be selected according to the actual situation on site.

[0066] The analysis of the influence law of the air distribution volume on the gas migration in the gob is as follows: In order to study the oxygen concentration distribution map in the gob under different air distribution volumes in the gob, we studied the distribution of the oxygen concentration in the gob under different air distribution volumes, Figure 15 、 Figure 16 、 Figure 17 are the oxygen concentration distribution nephograms when the air distribution volumes are 1900 m 3 / min, 2500 m 3 / min, and 3500 m 3 / min respectively.

[0067] From Figure 15 、 Figure 16 、 Figure 17 it can be seen that the widths of the heat dissipation zones on the intake side are 135 m, 150 m, and 170 m in sequence, the distances from the asphyxiation zone to the working face are 230 m, 253 m, and 290 m in sequence, and the widths of the oxidation and heating zones are 95 m, 103 m, and 120 m in sequence; the widths of the heat dissipation zones on the return air side are 10 m, 15 m, and 20 m in sequence, the distances from the asphyxiation zone to the working face are 110 m, 122 m, and 140 m in sequence, and the widths of the oxidation and heating zones are 100 m, 107 m, and 120 m in sequence. From the above analysis, it can be seen that increasing the air distribution volume can increase the widths of the heat dissipation zone and the oxidation and heating zone in the gob. Therefore, it is recommended that the mine minimize the air volume as much as possible on the premise of meeting the air volume required by the mine, which is beneficial to reducing the width of the oxidation and heating zone in the gob.

[0068] Step 4: Determine the carbon dioxide injection parameters for the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset perfusion condition; In the embodiment of the present disclosure, the Step 4 specifically includes: Among the three-zone distribution data of the goaf corresponding to each preset number of carbon dioxide injection ports, screen out the number of carbon dioxide injection ports corresponding to the minimum width of the oxidation heating zone, and use the screened number of carbon dioxide injection ports as the number of carbon dioxide injection ports for the goaf of the target coal mine; Among the three-zone distribution data of the goaf corresponding to each preset position of the carbon dioxide injection port, screen out the position of the carbon dioxide injection port corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened position of the carbon dioxide injection port as the position of the carbon dioxide injection port for the goaf of the target coal mine; Among the three-zone distribution data of the goaf corresponding to each preset carbon dioxide injection flow rate, screen out the carbon dioxide injection flow rate corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened carbon dioxide injection flow rate as the carbon dioxide injection flow rate for the goaf of the target coal mine; It should be noted that the A represents the optimal inerting effect under the same type of preset perfusion condition.

[0069] Among the three-zone distribution data of the goaf corresponding to each preset air distribution volume, screen out the air distribution volume corresponding to the minimum width of the oxidation heating zone, and use the screened air distribution volume as the air distribution volume for the goaf of the target coal mine.

[0070] In the embodiment of the present disclosure, the method further includes: Considering that the method of drilling from the ground to the goaf to inject carbon dioxide can be adopted, this method is also used as part of the simulation analysis in the simulation. Under the condition that the injection flow rate and the number of injection ports remain unchanged, change the position of the injection port to the ground position above the goaf. The simulation results are as Figure 18 shown.

[0071] As Figure 18 known, when drilling from the ground to the goaf to inject carbon dioxide, the drilling position is at a position 80 m away from the working face in the middle of the goaf, and the carbon dioxide injection speed is 0.3 m / s. As Figure 18 known, after the carbon dioxide enters the goaf, it flows out from the return airway of the working face along the air flow, has a greater impact on the oxidation zone on the return side of the goaf, has almost no impact on the oxidation on the intake side, and will also cause a serious low-oxygen problem at the return corner. Injecting carbon dioxide in the middle of the goaf is suitable for preventing the spontaneous combustion of the coal seam in the goaf after the mining face is closed.

[0072] For example, the effect analysis of preventive injection of carbon dioxide into the 2204 working face using the carbon dioxide injection parameter determination method based on the three-zone distribution in the goaf provided by this solution is as follows: By using the monitoring system to monitor the changes in relevant parameters such as CO gas, carbon dioxide gas, and temperature in the 2204 working face and the return air current in real time, the effect of liquid carbon dioxide in preventing coal spontaneous combustion in the goaf is analyzed. The real-time monitoring results at the monitoring points after injecting liquid carbon dioxide are as Figure 19 、 Figure 20 shown.

[0073] Analysis Figure 19 shows that before injecting liquid carbon dioxide, the carbon dioxide concentrations in the working face and the return air current were generally stable between 0.2% and 0.4%. When starting to inject carbon dioxide, the carbon dioxide concentrations at both places reached the highest value when the injection stopped. The highest value ranges of the carbon dioxide concentrations at both places were between 0.6% and 0.8%, and the carbon dioxide concentration on the return air side was higher than that in the working face. Subsequently, under the dilution effect of the air current, it decreased rapidly. After about three hours, it basically stabilized at about 0.2%.

[0074] Analysis Figure 20 of the temperature changes at the detection points during the injection of liquid carbon dioxide shows that about 4 hours after injecting liquid carbon dioxide, the temperature of the working face showed an obvious downward trend, and the temperature of the entire working face decreased by about 4.6 °C, and the temperature of the working face remained low after the injection stopped. At the same time, compared with the changes in the working face, the temperature of the return air current also showed an obvious downward trend, and the temperature decreased by 4.5 °C during the entire injection process. It shows that when liquid carbon dioxide injected into the goaf is converted into gas, it absorbs a large amount of heat, has a quite significant cooling effect on the temperature of the residual coal in the goaf, and inhibits the accumulation of the temperature of the residual coal in the goaf.

[0075] Analysis Figure 21 of the CO concentrations in the working face and the return air current shows that before injecting liquid carbon dioxide, the CO concentration showed a gradually increasing trend, and the highest value of the CO concentration on the return air side reached 10 ppm. It shows that the relatively slow mining speed of the 2204 working face results in sufficient contact time between the residual coal in the goaf and oxygen, enhancing the degree of coal-oxygen combination, and the temperature begins to accumulate and release gas. After promptly injecting liquid carbon dioxide for 4 hours, the CO concentration in the working face dropped to the range of 1 ppm - 2 ppm, and the CO concentration on the return air side dropped to the range of 2 ppm - 3 ppm. The CO concentrations of the gas in the working face and the return air current both decreased significantly.

[0076] According to on-site real-time gas detection, the concentrations of CO and carbon dioxide gas and the temperature at the working face gradually returned to normal values at 20:00. At 22:00, the concentrations of CO and carbon dioxide gas in the return air current were 3.3 ppm and 0.24% respectively. Subsequently, gas detection at the upper corner and other places found that they all met the operation standards. This shows that the injection of liquid carbon dioxide effectively inhibits the reaction between the residual coal in the goaf and oxygen, and can play a good preventive role in the spontaneous combustion of coal in the goaf.

[0077] The analysis of the effect of preventive injection of carbon dioxide into the 4215 working face using the carbon dioxide injection parameter determination method based on the three-zone distribution in the goaf provided by this scheme is as follows: By monitoring the changes in relevant parameters such as CO gas, carbon dioxide gas, and temperature of the 4215 working face and the return air current through the monitoring system in real time, the effect of liquid carbon dioxide in preventing the spontaneous combustion of coal in the goaf is analyzed. The real-time monitoring results of the monitoring points after injecting liquid carbon dioxide are as Figure 22 、 Figure 23 shown.

[0078] Analysis Figure 22 shows that before injecting liquid carbon dioxide, the carbon dioxide concentrations at the working face and the return air current were generally stable and remained at a low level. When starting to inject carbon dioxide, the carbon dioxide concentrations at the working face and the return air current began to increase rapidly, reaching the highest values at the end of injection. Subsequently, under the dilution effect of the air current, they decreased rapidly. After about three hours, they basically stabilized at the normal concentration.

[0079] By analyzing Figure 23 the change in the temperature of the monitoring points during the injection of liquid carbon dioxide, it is found that about two and a half hours after injecting liquid carbon dioxide, the temperature at the working face showed an obvious downward trend, and the temperature of the entire working face decreased by about 2.4 °C. Moreover, the temperature at the working face remained low after the injection stopped. At the same time, compared with the change at the working face, the temperature of the return air current also decreased significantly, with a temperature drop of 1.8 °C during the entire injection process. This shows that when liquid carbon dioxide injected into the goaf is converted into gas, it absorbs a large amount of heat, has a quite significant cooling effect on the temperature of the residual coal in the goaf, and inhibits the accumulation of the temperature of the residual coal in the goaf.

[0080] By analyzing Figure 24From the variation of CO concentration in the middle working face and the return air current, it can be seen that before injecting liquid carbon dioxide, the CO concentration showed a gradually increasing trend, and the highest value of CO concentration in the working face reached 9 ppm. This indicates that the relatively slow mining speed of the 4215 working face resulted in sufficient contact time between the residual coal in the goaf and oxygen, enhancing the degree of coal-oxygen complexation, and the temperature began to accumulate and release gas. After promptly injecting liquid carbon dioxide for 6 hours, the CO concentrations of the gas in the working face and the return air current both decreased significantly. According to the on-site real-time gas detection, at 20:00, the CO and carbon dioxide gas concentrations and temperature in the working face gradually returned to normal values. At 22:00, the CO and carbon dioxide gas concentrations in the return air current were 2 ppm and 0.22% respectively. Subsequently, gas detection at the upper corner and other places found that they all met the operation standards. This shows that injecting liquid carbon dioxide effectively inhibits the reaction between the residual coal in the goaf and oxygen, and can play a good preventive role in coal spontaneous combustion in the goaf.

[0081] By sorting out the on-site measured data of injecting liquid carbon dioxide underground in the 4215 and 2204 fully mechanized mining faces, comparing and analyzing the changes in relevant parameters such as CO gas, carbon dioxide gas, and temperature in the working face and the return air current, and then analyzing the effect of liquid carbon dioxide in preventing coal spontaneous combustion in the goaf, it is found that injecting liquid carbon dioxide effectively inhibits the reaction between the residual coal in the goaf and oxygen, and can play a good preventive role in coal spontaneous combustion in the goaf.

[0082] In summary, a method for determining carbon dioxide perfusion parameters based on the three-zone distribution in the goaf proposed in this embodiment can accurately determine the optimal carbon dioxide injection process technical parameters based on quantitative analysis of the three-zone distribution data.

[0083] Embodiment 2 Figure 25 As shown in the structure diagram of a system for determining carbon dioxide perfusion parameters based on the three-zone distribution in the goaf provided by an embodiment of the present application, Figure 25 As shown, the system includes: An acquisition module 100, configured to acquire the roadway layout data of the fully mechanized mining face of the target coal mine, the measured data of the fully mechanized mining face, and the model parameters of the fully mechanized mining face; Among them, the roadway layout data of the fully mechanized mining face includes: The shape, length, net width, net height, and net cross-sectional area of the belt conveyor gateway, the shape, length, net width, net height, and net cross-sectional area of the return air gateway, the shape, length, net width, net height, and net cross-sectional area of the auxiliary conveyor gateway, the shape, length, net width, net height, and net cross-sectional area of the cutting eye, the shape, length, net width, net height, and net cross-sectional area of the main withdrawal roadway, and the shape, length, net width, net height, and net cross-sectional area of the auxiliary withdrawal roadway; The measured data of the fully mechanized mining face includes: The intake air volume of the fully mechanized mining face, the air velocity at the intake air opening of the fully mechanized mining face, and the oxygen concentration; A building module 200 for constructing a numerical simulation model of the gob area of the fully mechanized coal mining face according to the model parameters of the fully mechanized coal mining face; A simulation module 300 for inputting the numerical simulation model of the gob area into the COMSOL numerical simulation software, and then respectively simulating and analyzing the three-zone distribution data of the gob area under each preset perfusion condition by using the COMSOL numerical simulation software and the measured data of the fully mechanized coal mining face; It should be noted that a multi-field coupling mathematical model for spontaneous combustion in the gob area is internally coupled in the COMSOL numerical simulation software; Among them, the multi-field coupling mathematical model for spontaneous combustion in the gob area includes: an equation for the steady-state porosity distribution characteristics of coal and rock in the gob area, a flow field control equation, a material field control equation, and an adsorption condition control equation; The flow field control equation, the material field control equation, and the adsorption condition control equation are set in the Darcy's law module of the COMSOL numerical simulation software.

[0084] The calculation formula of the equation for the steady-state porosity distribution characteristics of coal and rock in the gob area is as follows:

[0085]

[0086] In the formula, is the swelling coefficient of caving, is the swelling coefficient after compaction, is the swelling coefficient of the lower part of the gob area near the working face, is the initial swelling coefficient of caving, is the first adjustment parameter, is the second adjustment parameter, is the attenuation rate of the swelling coefficient of the caving coal and rock mass with the distance from the solid wall, is the attenuation rate of the swelling coefficient of the caving coal and rock mass in the working face, is the attenuation rate from the gob area roof, d 0 is the distance from the point (x, y, z) to the solid wall of the gob area, d 1 is the distance from the point (x, y, z) to the working face, d 2 is the distance from the point (x, y, z) to the bottom boundary of the gob area, b 0 is the adjustment parameter along the depth direction of the gob area, b 1 is the adjustment parameter along the working face direction, is the porosity distribution function; The calculation formula of the flow field control equation is as follows:

[0087] In the formula, is the fluid pressure, is the local acceleration under unsteady flow conditions, is the viscous stress term describing the fluid shear viscosity effect, is the dynamic viscosity, is the permeability, is the internal inertia resistance coefficient, is the mixed gas density, is the velocity vector, is the mass source term, is the porosity of coal and rock in the gob area, is the external force vector; The calculation formula of the material field control equation is as follows:

[0088]

[0089] In the formula, is the diffusion flux, is the material concentration, is the reaction rate, is the material source term, is the dispersion coefficient, is the effective diffusion coefficient; The calculation formula of the adsorption condition control equation is as follows:

[0090] In the formula, is the adsorption concentration, is the adsorption condition control equation.

[0091] Among them, the three-zone distribution data includes: the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the intake side, and the width of the heat dissipation zone, the width of the oxidation heating zone, and the width of the asphyxiation zone on the return air side; The preset perfusion conditions include: The number of preset carbon dioxide injection ports, the positions of the preset carbon dioxide injection ports, the preset carbon dioxide injection flow rates, and the preset air distribution volumes.

[0092] The determination module 400 is configured to determine the carbon dioxide perfusion parameters of the gob area of the target coal mine according to the three-zone distribution data of the gob area under each preset perfusion condition; In the embodiments of the present disclosure, the construction module 200 is further configured to: Construct a three-dimensional gob area numerical model of the fully mechanized coal mining face according to the fully mechanized coal mining face model parameters; The numerical model of the goaf of the fully mechanized working face is obtained by meshing the three-dimensional goaf numerical model with unstructured orthogonal hexahedral meshes.

[0093] In the embodiment of the present disclosure, the simulation module 300 is further configured to: Input the measured data of the fully mechanized working face into the Darcy's law module in the COMSOL numerical simulation software, and then simulate the oxygen concentration distribution nephogram of the goaf under each preset perfusion condition based on the Darcy's law module; Analyze the oxygen concentration distribution nephogram of the goaf under each preset perfusion condition to obtain the three-zone distribution data of the goaf under each preset perfusion condition.

[0094] In the embodiment of the present disclosure, the determination module 400 is further configured to: Among the three-zone distribution data of the goaf corresponding to each preset number of carbon dioxide injection ports, screen out the number of carbon dioxide injection ports corresponding to the minimum width of the oxidation heating zone, and use the screened number of carbon dioxide injection ports as the number of carbon dioxide injection ports for the goaf of the target coal mine; Among the three-zone distribution data of the goaf corresponding to each preset position of the carbon dioxide injection port, screen out the position of the carbon dioxide injection port corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened position of the carbon dioxide injection port as the position of the carbon dioxide injection port for the goaf of the target coal mine; Among the three-zone distribution data of the goaf corresponding to each preset carbon dioxide injection flow rate, screen out the carbon dioxide injection flow rate corresponding to the minimum width of the oxidation heating zone when the inerting effect is A, and use the screened carbon dioxide injection flow rate as the carbon dioxide injection flow rate for the goaf of the target coal mine; Among the three-zone distribution data of the goaf corresponding to each preset air distribution volume, screen out the air distribution volume corresponding to the minimum width of the oxidation heating zone, and use the screened air distribution volume as the air distribution volume for the goaf of the target coal mine.

[0095] In summary, a carbon dioxide perfusion parameter determination system based on the three-zone distribution of the goaf proposed in this embodiment can accurately determine the optimal carbon dioxide injection process technical parameters based on the quantitative analysis of the three-zone distribution data.

[0096] Embodiment III To implement the above embodiment, the present disclosure also proposes an electronic device, including: a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the method described in Embodiment I is implemented.

[0097] Embodiment IV To implement the above embodiments, the present disclosure also provides a computer-readable storage medium having a computer program stored thereon, and when the program is executed by a processor, the method described in Embodiment 1 is implemented.

[0098] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without conflict, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0099] Any process or method description shown in a flowchart or described in any other way herein may be understood to represent a module, segment, or portion of code including one or more executable instructions for implementing a customized logic function or process, and the scope of the preferred embodiments of the present application includes additional implementations, where the functions may be executed in a substantially simultaneous manner or in an order opposite to that shown or discussed, according to the functions involved, which should be understood by those skilled in the art to which the embodiments of the present application pertain.

[0100] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present application. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present application.

Claims

1. A method for determining carbon dioxide perfusion parameters based on three-zone distribution of goaf, characterized in that: The method comprises: Acquire the tunnel layout data of the fully mechanized mining face of the target coal mine, the measured data of the fully mechanized mining face, and the model parameters of the fully mechanized mining face; According to the fully mechanized mining face model parameters, a numerical simulation model of the goaf area of ​​the fully mechanized mining face is constructed; The goaf numerical simulation model is input into COMSOL numerical simulation software, and then the COMSOL numerical simulation software and the measured data of the fully mechanized mining face are used to simulate and analyze the three-zone distribution data of the goaf under each preset injection condition; Determine the carbon dioxide injection parameters of the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset injection condition; The three-band distribution data include: the heat dissipation band width, oxidation warming band width and suffocation band width on the air inlet side, and the heat dissipation band width, oxidation warming band width and suffocation band width on the return air side.

2. The method according to claim 1, characterized in that The tunnel layout data of the fully mechanized mining working face includes: The shape, length, clear width, clear height, and clear cross-sectional area of ​​the rubber transport chute, the shape, length, clear width, clear height, and clear cross-sectional area of ​​the return air chute, the shape, length, clear width, clear height, and clear cross-sectional area of ​​the auxiliary transport chute, the shape, length, clear width, clear height, and clear cross-sectional area of ​​the cut-eye, the shape, length, clear width, clear height, and clear cross-sectional area of ​​the main retreat lane, and the shape, length, clear width, clear height, and clear cross-sectional area of ​​the auxiliary retreat lane; The measured data of the fully mechanized mining face include: Air intake volume of fully mechanized mining working face, wind speed at the air inlet of fully mechanized mining working face, and oxygen concentration; The preset perfusion conditions include: The number of preset carbon dioxide injection ports, the position of preset carbon dioxide injection ports, the preset carbon dioxide injection flow rate, and the preset air distribution volume.

3. The method according to claim 2, characterized in that The method of constructing a goaf area numerical simulation model of the fully mechanized mining working face according to the fully mechanized mining working face model parameters comprises: Constructing a three-dimensional goaf numerical model of the fully mechanized mining working face according to the fully mechanized mining working face model parameters; The three-dimensional goaf area numerical model is meshed using an unstructured orthogonal hexahedral grid to obtain a goaf area numerical simulation model of the fully mechanized mining working face.

4. The method according to claim 3, characterized in that The COMSOL numerical simulation software is internally coupled with a multi-field coupling mathematical model of spontaneous combustion in goaf; The multi-field coupling mathematical model of spontaneous combustion in goaf includes: the characteristic equation of the steady-state porosity distribution of coal and rock in goaf, the flow field control equation, the material field control equation and the adsorption condition control equation; The flow field control equation, the material field control equation and the adsorption condition control equation are set in the Darcy's law module of the COMSOL numerical simulation software.

5. The method according to claim 4, characterized in that The calculation formula of the steady-state porosity distribution characteristic equation of the coal rock in the goaf is as follows: In the formula, is the coefficient of expansion of the falling is the expansion coefficient after compaction, is the expansion coefficient of the lower part of the goaf near the working face, is the initial expansion coefficient, is the first adjustment parameter, is the second adjustment parameter, is the attenuation rate of the expansion coefficient of the caving coal rock mass at a distance from the solid wall, is the attenuation rate of the expansion coefficient of coal and rock mass falling at the working face, is the attenuation rate of the goaf roof, d0 is the distance from the point (x, y, z) to the goaf solid wall, d1 is the distance from the point (x, y, z) to the working surface, d2 is the distance from the point (x, y, z) to the goaf floor boundary, b0 is the adjustment parameter along the goaf depth direction, b1 is the adjustment parameter along the working surface direction, is the porosity distribution function; The calculation formula of the flow field control equation is as follows: In the formula, is the fluid pressure, is the local acceleration under unsteady flow conditions, is the viscous stress term describing the shear viscosity effect of the fluid, is the dynamic viscosity, is the permeability, is the internal inertial resistance coefficient, is the density of the mixed gas, is the velocity vector, is the mass source term, is the porosity of coal rock in the goaf, is the external force vector; The calculation formula of the material field control equation is as follows: In the formula, is the diffusion flux, is the substance concentration, is the reaction rate, is the material source term, is the diffusion coefficient, is the effective diffusion coefficient; The calculation formula of the adsorption condition control equation is as follows: In the formula, is the adsorption concentration, is the control equation of adsorption conditions.

6. The method according to claim 5, characterized in that The method of using the COMSOL numerical simulation software and the measured data of the fully mechanized mining face to simulate and analyze the three-zone distribution data of the goaf under each preset injection condition includes: The measured data of the fully mechanized mining face is input into the Darcy's law module in the COMSOL numerical simulation software, and then the oxygen concentration distribution cloud diagram of the goaf under each preset injection condition is simulated based on the Darcy's law module; The oxygen concentration distribution cloud diagram of the goaf under each preset perfusion condition is analyzed to obtain the three-zone distribution data of the goaf under each preset perfusion condition.

7. The method according to claim 6, characterized in that The step of determining the carbon dioxide injection parameters of the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset injection condition includes: In the three-zone distribution data of the goaf corresponding to each preset number of carbon dioxide injection ports, the number of carbon dioxide injection ports corresponding to the minimum width of the oxidation warming zone is screened out, and the screened number of carbon dioxide injection ports is used as the number of carbon dioxide injection ports in the goaf of the target coal mine; In the three-zone distribution data of the goaf corresponding to each preset carbon dioxide injection port position, the carbon dioxide injection port position corresponding to the minimum width of the oxidation warming zone when the inerting effect is A is screened out, and the screened carbon dioxide injection port position is used as the carbon dioxide injection port position of the goaf of the target coal mine; In the three-zone distribution data of the goaf corresponding to each preset carbon dioxide injection flow rate, the carbon dioxide injection flow rate corresponding to the minimum width of the oxidation warming zone when the inerting effect is A is screened out, and the screened carbon dioxide injection flow rate is used as the carbon dioxide injection flow rate of the goaf of the target coal mine; In the three-zone distribution data of the goaf corresponding to each preset air supply volume, the air supply volume corresponding to the minimum width of the oxidation temperature rising zone is screened out, and the screened air supply volume is used as the air supply volume of the goaf of the target coal mine.

8. A system for determining carbon dioxide perfusion parameters based on three-zone distribution of goaf, characterized in that: The system comprises: An acquisition module is used to acquire the tunnel layout data of the fully mechanized mining face of the target coal mine, the measured data of the fully mechanized mining face, and the model parameters of the fully mechanized mining face; A construction module, used to construct a numerical simulation model of the goaf area of ​​the fully mechanized mining working face according to the fully mechanized mining working face model parameters; A simulation module, used for inputting the numerical simulation model of the goaf into COMSOL numerical simulation software, and then using the COMSOL numerical simulation software and the measured data of the fully mechanized mining working face to simulate and analyze the three-zone distribution data of the goaf under each preset injection condition; A determination module, used to determine the carbon dioxide injection parameters of the goaf of the target coal mine according to the three-zone distribution data of the goaf under each preset injection condition; The three-band distribution data include: the heat dissipation band width, oxidation warming band width and suffocation band width on the air inlet side, and the heat dissipation band width, oxidation warming band width and suffocation band width on the return air side.

9. An electronic device, characterized in that: include: A memory, a processor, and a computer program stored in the memory and executable on the processor, wherein when the processor executes the program, the method according to any one of claims 1 to 7 is implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.

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