A cemented filling goaf method for calculating the disposal amount of power plant flue gas

Abstract

The application discloses a kind of cemented filling goaf in power plant flue gas disposal quantity calculation method, the method includes: obtaining filling goaf volume and buried depth etc. Geological data, the physicochemical characteristics such as mineral composition, porosity, permeability of cemented filling body are determined by experiment;Accordingly, the theoretical flue gas fixation capacity of cemented filling body is calculated;Through cemented filling body mineralization sealing flue gas test, the flue gas diffusion range under different injection pressure is obtained, and then the mineralization sealing flue gas efficiency is obtained;According to the test data, the numerical model of cemented filling goaf sealing flue gas is established, the flue gas migration and chemical reaction rate are verified and analyzed, and the mineralization sealing flue gas efficiency is corrected according to the simulation result;Potential formula of filling material sealing power plant flue gas is established, and the flue gas disposal quantity is calculated;According to the measured data of filling disposal power plant flue gas, the potential formula of filling sealing power plant flue gas is verified.The calculation principle is simple, which provides a flue gas injection quantity theoretical calculation method for filling mining disposal process of power plant flue gas.

Description

Technical Field

[0001] This invention relates to a method for calculating the amount of flue gas that can be disposed of in a cemented backfill goaf, belonging to the field of mine waste gas treatment technology. Background Technology

[0002] Currently, actively and steadily promoting carbon peaking and carbon neutrality is an important environmental protection theme. In June 2022, seven departments, including the Ministry of Ecology and Environment, jointly issued the "Implementation Plan for Synergistic Efficiency Improvement in Pollution Reduction and Carbon Reduction," promoting synergistic efficiency improvement in the industrial sector, encouraging key industry enterprises to explore and adopt technologies and processes for the synergistic control of multiple pollutants and greenhouse gases, carry out collaborative innovation, and promote the application of carbon capture, utilization, and storage technologies in the industrial sector. As my country's air pollutant emission standards continue to tighten, regulatory efforts continue to increase, and incentive policies continue to advance, the scale of industrial flue gas treatment continues to expand. However, flue gas treatment in the thermal power industry is concentrated on ultra-low emission retrofitting of coal-fired power plants, resulting in a significant increase in unit energy consumption, urgently requiring innovative methods for power plant flue gas treatment.

[0003] Carbon dioxide capture, utilization, and storage (CO2 capture, utilization, and storage) technologies are essential for achieving significant CO2 emission reductions at present. Storage technologies mainly include marine storage, geological storage, and mineralization storage. The concept of mineralization storage was first proposed by Seifritz in 1990. It mainly mimics the natural process of rock weathering and CO2 absorption, utilizing mineral raw materials to undergo carbonation reactions with CO2 gas to obtain stable solid carbonates. Currently, my country's industrial solid waste (coal gangue, fly ash, steel slag, etc.) contains active substances such as calcium and magnesium oxides and hydroxides, all of which can be used for CO2 and SO2 mineralization. Currently, the main research issues in international CO2 capture and storage technology development include the mechanisms and laws of CO2 adsorption and migration in geological storage systems, its phase state and its changes in strata, chemical reactions, and solidification conditions. Potential calculations generally employ numerical simulations of CO2 transport reactions based on actual geological models.

[0004] Based on the CO2 sequestration mechanism and sequestration potential calculation, and combined with the co-filling treatment of coal-based solid waste and power plant flue gas, it is urgent to propose a method for calculating the amount of power plant flue gas to be disposed of in cemented backfilled goaf areas. According to the volume of the backfilled goaf and the physicochemical properties of the backfilling material, a potential formula for the backfilling material to sequestrate power plant flue gas should be established, providing a reference for industrial trials of co-filling and sequestration of mine solid waste and power plant flue gas. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this paper provides a method for calculating the amount of flue gas that can be disposed of in cemented backfill goaf areas. This method can effectively and accurately determine the mineral storage potential of flue gas in backfill goaf areas, and promote the research and development of co-filling and storage of mine solid waste with power plant flue gas.

[0006] To achieve the above technical objectives, this invention proposes a method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf. First, geological data such as the volume and depth of the backfill goaf are obtained, and the physicochemical properties of the cemented backfill, including mineral composition, porosity, pore structure, and permeability, are determined experimentally. Based on this, the theoretical flue gas fixation capacity of the cemented backfill is calculated. Through experiments on mineralizing and storing flue gas in the cemented backfill, the flue gas diffusion range under different injection pressures is obtained, thus determining the efficiency of mineralized flue gas storage. A potential formula for storing power plant flue gas using backfill materials is established, and the amount of flue gas disposed of is calculated. A numerical model for storing flue gas in cemented backfill goaf is established based on experimental data to study the flue gas transport and chemical reaction rates, and the efficiency of mineralized flue gas storage is corrected based on the simulation results. Finally, the potential formula for storing power plant flue gas using backfill is verified based on measured data of flue gas disposed of in backfill.

[0007] Technical solution: A method for calculating the amount of flue gas to be disposed of in a cemented backfill goaf, comprising the following steps:

[0008] S1. Acquire data, including geological data of the filling goaf, physicochemical properties of the cemented filling body, and component content of power plant flue gas.

[0009] S2. Based on the mass fractions of CaO, MgO, and FeO in the backfill material, and considering the mineralization and fixation mechanism of CO2 and SO2, calculate the theoretical flue gas fixation capacity (m) per unit volume of cemented backfill. 理论烟气 ;

[0010] S3. Through the mineralization and sealing of flue gas by cemented backfill, obtain flue gas composition data and thermodynamic data during the reaction process, test the diffusion range of power plant flue gas in cemented backfill material under different injection pressures, and obtain the flue gas solidification utilization rate ξ per unit mass of cemented backfill.

[0011] S4. Based on the experimental data from step S3, establish a numerical model for sealing flue gas in cemented backfill goaf, verify and analyze the flue gas migration and chemical reaction rate, and correct the efficiency ξ of mineralized sealed flue gas based on the simulation results.

[0012] S5. Establish a potential formula for sealing power plant flue gas with filling materials, and calculate the amount of flue gas to be disposed of in cemented goaf areas.

[0013] Optionally, in one embodiment of the present invention, in step S1, the geological data includes at least one of the volume of the filling goaf and the burial depth; the physicochemical properties of the cemented filling body include at least one of the mineral composition, porosity, pore structure, and permeability.

[0014] Optionally, in one embodiment of the present invention, in step S2, the theoretical flue gas fixation capacity m of the cemented filling body per unit volume is... 理论烟气 Calculate according to the following formula:

[0015]

[0016]

[0017]

[0018] Where, m co2 m so2 These are the theoretical carbon and sulfur fixation capacities per unit volume of cemented infill, w B It is the mass fraction of CaO, MgO, and FeO in the filling material, M B M represents the molar mass of CaO, MgO, and FeO. CO2 M SO2 These are the molar masses of CO2 and SO2, respectively.

[0019] Optionally, in one embodiment of the present invention, the specific steps of the mineralization and sealing flue gas test of the cemented filling body in step S3 are as follows:

[0020] S31. Prepare a test bench for the mineralization and sealing of flue gas by filling materials. The test bench includes an electronic balance and a support frame with baffles around its perimeter. Gas injection valves III and IV are respectively installed on the two side walls of the support frame. A closed transparent box is fixed to each side of the support frame. A temperature sensor, a gas concentration sensor, and a pressure sensor are installed inside the closed transparent box. The grouting valve on the support frame is connected to the filling material storage area via a grouting pipeline for injecting filling material to form cemented filling material. A carbon dioxide concentration sensor is embedded within the material. Gas injection valve II on the closed transparent box is connected to a vacuum pump and a high-pressure gas cylinder via a gas injection pipeline. A gas flow meter is installed on the main pipeline of the gas injection pipeline connected to the high-pressure gas cylinder.

[0021] S32. After connecting the pipeline through the grouting valve, inject the filling material into the support frame with baffles around it and weigh it. Open the air injection valve II, air injection valve III, and air injection valve IV. Turn on the vacuum pump to evacuate the sealed transparent box. After evacuating the sealed transparent box to a vacuum, turn off the vacuum pump and all valves.

[0022] S33. Open the high-pressure gas cylinder through gas injection valve I, gas injection valve II, and gas injection valve III. Adjust the flow rate of injected flue gas by controlling the flow meter. Start timing at the same time. The gas concentration monitor, temperature sensor, and pressure sensor in the transparent sealed box automatically record the changes in gas concentration, temperature, and pressure in the box over time. The right side of the box is a blank control group.

[0023] S34. When the gas concentration sensor in the left transparent sealed box no longer fluctuates, close the gas injection valve I to end the test;

[0024] S35. After the test, the cemented backing material sample after the flue gas was fixed was taken out. The original backing material sample and the cemented backing material sample after the flue gas was mineralized were analyzed by XRD and SEM-EDS respectively to determine the changes in phase and surface morphology of the backing material before and after the flue gas was mineralized.

[0025] S36. The CO2, SO2, and NO concentrations of the filling material between different cross sections are measured using a gas concentration sensor pre-embedded in the specimen. x The diffusion coefficient was used to obtain the CO2, SO2, and NO content inside the filling material under different injection pressures. x The extent of its spread;

[0026] S37. The theoretical flue gas fixation capacity per unit mass of the test material obtained in step S2, m 理论烟气 Based on the pressure drop P inside the transparent sealed box before and after the mineralization and storage reaction 矿化封存 The actual disposal volume (m) of the mineralized flue gas containing filling material was obtained. 实际烟气 :

[0027]

[0028] In the formula, P 矿化封存 V is the pressure drop inside the transparent sealed box before and after the mineralization and storage reaction; T is the reaction temperature; Z is the flue gas compressibility factor, which depends on pressure and temperature; R is the gas constant, 8.314 J / (mol·K); m 试验材料 For the quality of the test materials.

[0029] S38, according to m 实际烟气 and m 理论烟气 Calculate the flue gas solidification utilization rate ξ of the cemented filling material per unit mass under different diffusion ranges:

[0030]

[0031] Optionally, in one embodiment of the present invention, the gas concentration sensor includes a carbon dioxide concentration monitor, a sulfur dioxide concentration monitor, and a nitrogen concentration monitor. Power plant flue gas mainly contains CO2, SO2, and NO. x There are three gas components, so concentration sensors for these three gases are set up for concentration monitoring.

[0032] Optionally, in one embodiment of the present invention, step S4, the step of establishing the numerical analysis of sealed flue gas in cemented backfill goaf, includes:

[0033] S41. Model the underground rock, formation characteristics and flue gas reaction process using known data, including defining the formation boundary conditions, the original state of the filling material and the specific location of the flue gas injection hole;

[0034] S42. Set up the scenario for the mineralization and storage experiment, set up reaction factors including flue gas injection pressure, rate, and concentration, define the heterogeneous multiphase multicomponent reaction transport equation in TOUGHREACT, input the thermodynamic data of the geochemical reaction, and set the basic laws of the mineralization reaction process.

[0035] S43. Discretize the time and space grids as needed, and adjust the grid size to capture key physical phenomena; select an appropriate time step to ensure the accuracy and stability of the simulation.

[0036] S44. Conduct multiphase and multicomponent reaction transport simulation, fit and analyze the simulation data and experimental data, and correct the flue gas solidification utilization rate ξ of the unit mass cemented filling body.

[0037] Optionally, in one embodiment of the present invention, in step S41, the geological boundary conditions include the coal seam burial depth, the height of the backfill body, the length of the coal mining face, and the advance distance; the key parameters of the backfill material include its density, permeability, porosity, compressive strength, flue gas injection rate, etc.; and the specific location of the flue gas injection hole includes the strike distance of the borehole from the cut and the dip distance from the boundary of the working face.

[0038] Optionally, in one embodiment of the present invention, step S44 specifically includes determining the flue gas diffusion range and reaction equilibrium time based on the TOUGHREACT numerical simulation results, and correcting the mineralization and storage efficiency of the filling material obtained from the experiment.

[0039] Optionally, in one embodiment of the present invention, in step S5, the formula for the potential of the filling material to seal power plant flue gas is as follows:

[0040] T 烟气 =m 理论烟气 ·ρ m ·v·(1-φ)·ξ

[0041] In the formula, T 烟气 To preserve the flue gas potential of power plants using filling materials, m 理论烟气 ρ represents the theoretical flue gas fixation capacity per unit mass of cemented packing. m denoted as density of the filling material, v as volume of the filled goaf, φ as porosity of the filling material, and ξ as flue gas solidification utilization rate of the filling material.

[0042] Optionally, in one embodiment of the present invention, in step S5, the minimum flue gas disposal volume T is determined based on the mineralization and sealing flue gas test of the cemented filling body under the condition of minimum flue gas diffusion range. 烟气 The maximum flue gas handling capacity T is derived based on the theoretical flue gas fixation capacity of the cemented filling body. 烟气 / ξ.

[0043] The beneficial effects achieved by this invention are as follows: This method is based on the mineralization reaction that occurs after flue gas is injected into the backing material. Through experiments on mineralized flue gas storage in cemented backing bodies, a potential formula for storing power plant flue gas using backing materials is established. This formula is then corrected based on numerical simulation results of flue gas storage in cemented backing goaf areas, enabling accurate calculation of the amount of flue gas that can be disposed of in underground power plants. Furthermore, from multiple perspectives, including thermodynamic stability, insolubility, geological process stability, and environmental friendliness, it can be confirmed that mineralized flue gas storage is one of the most stable storage methods, and underground backing storage of flue gas can achieve large-scale flue gas disposal. The method for calculating the amount of power plant flue gas disposed of in cemented backing goaf areas provides a reference for industrial trials of co-located backing and storage of flue gas from mining solid waste and power plants, promoting the research and development of co-located backing and storage of flue gas from mining solid waste and power plants. Attached Figure Description

[0044] Figure 1 This is a flowchart illustrating the implementation of the method of the present invention.

[0045] Figure 2 This is a schematic diagram of the structure of the test bench for the ability of filling material to mineralize and seal flue gas in an embodiment of the present invention.

[0046] The figures in the diagram are labeled as follows:

[0047] 1-High-pressure gas cylinder, 2-Gas flow meter, 3-Injection valve 1, 4-Pressure sensor, 5-Vacuum pump, 6-Cemented filling material, 7-Grouting valve, 8-Injection valve 2, 9-Carbon dioxide concentration sensor inside the material, 10-Temperature sensor, 11-Carbon oxide concentration sensor, 12-Sulfur dioxide concentration sensor, 13-Nitrogen concentration sensor, 14-Electronic balance, 15-Computer, 16-Injection pipeline, 17-Enclosed transparent box, 18-Support frame with baffles on all sides, 19-Sensor signal transmission line, 20-Injection valve 3, 21-Injection valve 4. Detailed Implementation

[0048] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0049] like Figure 1As shown, this invention proposes a method for calculating the flue gas disposal capacity in cemented backfill goaf areas. First, geological data such as the volume and depth of the backfill goaf are obtained. Then, the physicochemical properties of the cemented backfill, including mineral composition, porosity, pore structure, and permeability, are determined experimentally. Based on these, the theoretical flue gas retention capacity per unit volume of cemented backfill is calculated. Through experiments on the mineralization and sequestration of flue gas by the cemented backfill, flue gas composition data and thermodynamic data of the reaction process are obtained, yielding the efficiency of the mineralization and sequestration of flue gas per unit volume of cemented backfill. A potential formula for the backfill material to sequestrate power plant flue gas is established, and the flue gas disposal capacity is calculated. Based on experimental data, a numerical model for the sequestration of flue gas in cemented backfill goaf areas is established to study flue gas migration, chemical reaction rates, and influencing factors. The calculation formula for the flue gas disposal capacity is then revised based on the simulation results.

[0050] The specific steps are as follows:

[0051] S1. Obtain geological data such as the volume and burial depth of the backfilled goaf, the physicochemical properties of the backfill material, and the component content of the power plant flue gas. The specific test methods are as follows:

[0052] Geological data: Determining the volume and depth of the goaf filling area is a conventional method. Specifically, it can be done by drawing a mine excavation plan based on the geological exploration results and determining the volume and depth of the goaf filling area through the drawings.

[0053] Physicochemical properties of filling materials: The density of cemented filling materials was determined by balance method, the material composition was obtained by X-ray diffraction, the porosity and pore structure of materials were obtained by mercury intrusion porosimetry and scanning electron microscopy, respectively, and the permeability was measured by steady-state method;

[0054] Component content of power plant flue gas: The concentration of various components in the flue gas is measured by gas chromatography.

[0055] S2. Based on the mass fractions of CaO, MgO, and FeO in the filling material, and considering the mineralization and fixation mechanism of CO2 and SO2, the theoretical flue gas fixation capacity m per unit mass of cemented filling body is calculated using the following formula. 理论烟气 .

[0056]

[0057]

[0058]

[0059] Where, m co2 m so2 These are the theoretical carbon and sulfur fixation capacities per unit volume of cemented infill, w B It is the mass fraction of CaO, MgO, and FeO in the filling material, M B M represents the molar mass of CaO, MgO, and FeO.CO2 M SO2 These are the molar masses of CO2 and SO2, respectively.

[0060] S3. Based on the following test steps for mineralization and sealing of flue gas in cemented backfill, obtain flue gas composition and thermodynamic data during the reaction process, test the diffusion range of power plant flue gas in the cemented backfill material under different injection pressures, and obtain the flue gas solidification utilization rate ξ per unit mass of cemented backfill. This step aims to obtain a universally applicable flue gas solidification utilization rate under different diffusion ranges. Specifically, a simulation test is conducted using a test bench for the mineralization and sealing capacity of backfill materials. The specific test bench structure and its operation include the following steps:

[0061] S31. Prepare a test bench for the ability to mineralize and seal flue gas with filling materials. The test bench for the ability to mineralize and seal flue gas with filling materials includes a closed transparent box (17), a high-pressure gas cylinder (1), an electronic balance (14), a temperature sensor (10), a pressure sensor (4), a carbon dioxide concentration sensor (11), a sulfur dioxide concentration sensor (12), a nitrogen concentration sensor (13), an injection valve I (3), a grouting valve (7), a gas flow meter (2), a pipeline (16), a vacuum pump (5), and a support frame (18).

[0062] Two enclosed transparent boxes (17) are placed on the table and surrounded by a metal frame for fixation. A space is left between the two enclosed transparent boxes (17) for placing a support frame (18) to fix the adhesive filling material (6). The support frame (18) with baffles on all sides is mounted on the electronic balance (14) so ​​that the support frame (18) is placed in the middle of the electronic balance (14) and keeps the two enclosed transparent boxes (17) on both sides balanced.

[0063] The upper part of the support frame (18) is provided with a grouting valve (7). The grouting valve (7) is connected to the filling material storage area through a grouting pipeline. When the grouting valve (7) is opened, the filling material can be injected into the support frame (18) to form a cemented filling material (6). A carbon dioxide concentration sensor (9) is embedded in the cemented filling material (6) to detect the carbon dioxide concentration inside the cemented filling material (6).

[0064] Both sides of the enclosed transparent box (17) are equipped with gas injection valve II (8) on the upper part. The gas injection valve II (8) is connected to the vacuum pump (5) and the high-pressure gas cylinder (1) respectively through the gas injection pipeline (16). The gas injection valve I (3) and the flow meter (2) are also provided on the main gas injection pipeline (16) of the high-pressure gas cylinder (1). The vacuum pump (5) is used to evacuate the enclosed transparent box (17) on both sides, and the high-pressure gas cylinder (1) is used to inject flue gas into the enclosed transparent box (17) on both sides.

[0065] Gas injection valve III (20) and gas injection valve IV (21) are respectively installed on the left and right sides of the support frame (18). When the valves are turned on, the flue gas in the closed transparent box (17) enters the cemented filling material (6) in the support frame (18).

[0066] The two closed transparent boxes (17) are equipped with temperature sensors (10), carbon dioxide concentration monitors (11), sulfur dioxide concentration monitors (12) and nitrogen concentration monitors (13), and pressure sensors (4) are installed on the top of each box to automatically record the changes in pressure, temperature and gas concentration inside the box over time.

[0067] The pressure sensor (4), temperature sensor (10), carbon dioxide concentration monitor (11), sulfur dioxide concentration monitor (12), nitrogen concentration monitor (13), carbon dioxide concentration sensor inside the material (9), and flow meter (2) are all connected to the computer (15) through the sensor signal transmission line (19). The computer (15) controls the monitoring data and transmits it to the computer (15) in real time, thereby realizing the simulation test of mineralized sealing flue gas of cemented filling body and obtaining the flue gas diffusion capacity under different injection pressures.

[0068] S32. After connecting the grouting pipeline through the grouting valve (7), inject the filling material into the support frame (18) with baffles around it and weigh it. Open the air injection valve II (8), air injection valve III (20), and air injection valve IV (21). Turn on the vacuum pump (5) to evacuate the closed transparent box (17). After evacuating the closed transparent box (18) to a vacuum, turn off the vacuum pump (5) and all valves.

[0069] S33. Open the high-pressure gas cylinder (1) through gas injection valve I (3), gas injection valve II (8), and gas injection valve III (20). Adjust the flow rate of injected flue gas on the computer (15) by controlling the flow meter (2) and start timing at the same time. The carbon dioxide concentration monitor (11), sulfur dioxide concentration monitor (12), nitrogen concentration monitor (13), temperature sensor (10), and pressure sensor (4) in the transparent sealed box (17) automatically record the changes in gas concentration, temperature, and pressure in the box over time. The right side of the box is the blank control group.

[0070] S34. When the gas concentration sensors (11), (12), and (13) in the left transparent sealed box (17) no longer fluctuate, close the gas injection valve I (3) and the test ends.

[0071] S35. After the test, the cemented filling material (6) sample after the flue gas was fixed was taken out. The original filling material and the cemented filling material (6) sample after the flue gas was mineralized were analyzed by XRD and SEM-EDS respectively to determine the changes in phase and surface morphology of the filling material before and after the flue gas was mineralized.

[0072] S36. The CO2, SO2, and NO content of the filling material between different cross sections is determined by a gas concentration sensor (9) pre-embedded in the specimen. x The diffusion coefficient was used to obtain the CO2, SO2, and NO content inside the filling material under different injection pressures. x The diffusion range; the diffusion coefficient obtained in this step is to provide a basis for the numerical simulation in S4 (specifically, CO2, SO2, NO in S41). x The diffusion coefficient provides a parameter, and it is used to characterize the ability of flue gas to diffuse under different injection pressures. Since the flue gas diffusion range affects the material's mineralization ability, multiple sets of filling body mineralization and sealing flue gas tests were conducted using different injection pressures, and the resulting flue gas solidification utilization rate ξ was different.

[0073] S37. The theoretical flue gas fixation capacity per unit mass of the test material obtained in step S2, m 理论烟气 Based on the pressure drop P inside the transparent sealed box before and after the mineralization and storage reaction 矿化封存 The actual disposal volume (m) of the mineralized flue gas containing filling material was obtained. 实际烟气 :

[0074]

[0075] In the formula, P 矿化封存 V is the pressure drop inside the transparent sealed box before and after the mineralization and storage reaction; T is the gas volume inside the transparent sealed box; Z is the flue gas compressibility factor, which depends on pressure and temperature, and can be found in the national standard GB / T17747-2011 "Calculation of Natural Gas Compressibility Factor"; R is the gas constant, 8.314 J / (mol·K), a constant characterizing the thermodynamic properties of an ideal gas, defined by the American Bureau of Standards and Atmospheric Administration in 1976; m 试验材料 For the quality of the test materials.

[0076] S38, according to m 实际烟气 and m 理论烟气 Calculate the flue gas solidification utilization rate ξ of the cemented filling material per unit mass under different diffusion ranges:

[0077]

[0078] S4. Perform numerical simulation of the sealed flue gas in the cemented backfill goaf according to the following simulation analysis steps, and revise the calculation formula of flue gas disposal volume based on the simulation results.

[0079] Specifically, the simulation process includes the following steps:

[0080] S41. Model the underground rock, formation characteristics, and flue gas reaction process using known data, including defining formation boundary conditions, the original state of the backfill material, and the levels of CO2, SO2, and NO in the flue gas. x The diffusion coefficient (obtained from step S36 above) and the specific location of the flue gas injection hole, etc. In one example of this embodiment, the geological boundary conditions include the coal seam depth, backfill height, working face length, and advance distance. The key parameters of the backfill material include its density, permeability, porosity, compressive strength, and flue gas injection rate. The specific location of the flue gas injection hole includes the strike distance of the borehole from the cut and the dip distance from the working face length boundary. In other examples of this embodiment, other parameters may be used, determined according to the actual conditions of the goaf.

[0081] S42. Set up the scenario for the mineralization and storage experiment, including setting factors such as flue gas injection pressure, velocity, and concentration. Define the heterogeneous multiphase multicomponent reaction transport equation in TOUGHREACT, input the thermodynamic data of the geochemical reaction, and set the basic laws of the mineralization reaction process. The purpose of this embodiment is to simulate the mineralization and storage of flue gas in cemented backfill using fluid flow and geochemical transport modules, and to train and model the process using TOUGHREACT based on the software's built-in formula program.

[0082] S43. Discretize the time and space grids as needed, and adjust the grid size to capture key physical phenomena. Select an appropriate time step to ensure the accuracy and stability of the simulation.

[0083] S44. Conduct multiphase and multicomponent reaction transport simulation, fit and analyze the simulation data and experimental data, determine the flue gas diffusion range and reaction equilibrium time, and correct the mineralization and storage efficiency ξ of the filling material obtained from the experiment.

[0084] S5. Based on the test results, establish a potential formula for sealing power plant flue gas with filling materials, and calculate the flue gas disposal capacity of cemented goaf. The minimum flue gas disposal capacity is obtained from the test of sealing flue gas with mineralized cemented filling material under the condition of minimum flue gas diffusion range, and the maximum flue gas disposal capacity is obtained from the theoretical flue gas fixing capacity of cemented filling material.

[0085] T 烟气 =m 理论烟气 ·ρ m ·v·(1-φ)·ξ

[0086] In the formula, T 烟气 To preserve the flue gas potential of power plants using filling materials, m 理论烟气 ρ represents the theoretical flue gas fixation capacity per unit mass of cemented packing.m denoted as density of the filling material, v as volume of the filled goaf, φ as porosity of the filling material, and ξ as flue gas solidification utilization rate of the filling material.

[0087] S6. Based on the measured flue gas disposal volume of the power plant at different injection rates and diffusion ranges, verify the potential formula for sealing power plant flue gas with filling materials.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for calculating the amount of flue gas to be disposed of in a cemented backfill goaf of a power plant, characterized in that, Includes the following steps: S1. Acquire data, including geological data of the filling goaf, physicochemical properties of the cemented filling body, and component content of power plant flue gas. S2. Based on the mass fractions of CaO, MgO, and FeO in the backfill material, and considering the mineralization and fixation mechanism of CO2 and SO2, calculate the theoretical flue gas fixation capacity per unit volume of cemented backfill. m 理论烟气 ; S3. Through mineralization and sealing of flue gas using cemented backfill, obtain flue gas composition and thermodynamic data during the reaction process, test the diffusion range of power plant flue gas in cemented backfill material under different injection pressures, and obtain the flue gas solidification utilization rate per unit mass of cemented backfill. ξ ; The specific steps for the mineralization and flue gas preservation test of the cemented filling body are as follows: S31. Prepare a test bench for the ability to mineralize and seal flue gas with filling materials. The test bench includes an electronic balance (14) and a support frame (18) with baffles on all sides. Gas injection valves III (20) and IV (21) are respectively provided on the two side walls of the support frame (18). A closed transparent box (17) is fixed on each side of the support frame (18). A temperature sensor (10), a gas concentration sensor and a pressure sensor (4) are provided in the closed transparent box (17). The grouting valve (7) on the support frame (18) is connected to the filling material storage area through the grouting pipeline and is used to inject filling material to form cemented filling material (6). A carbon dioxide concentration sensor (9) is embedded in the material. The gas injection valve II (8) on the closed transparent box (17) is connected to a vacuum pump (5) and a high-pressure gas cylinder (1) through the gas injection pipeline (16). A gas flow meter (2) is provided on the main pipeline of the gas injection pipeline (16) connected to the high-pressure gas cylinder (1). S32. After connecting the pipeline through the grouting valve (7), inject the filling material into the support frame (18) with baffles around it and weigh it. Open the air injection valve II (8), air injection valve III (20), and air injection valve IV (21). Turn on the vacuum pump (5) to evacuate the closed transparent box (17). After evacuating the closed transparent box (19) to a vacuum, turn off the vacuum pump (5) and all valves. S33. Open gas injection valve I (3), gas injection valve II (8), gas injection valve III (20), open high-pressure gas cylinder (1), adjust the flow rate of injected flue gas by controlling flow meter (2), and start timing at the same time. The gas concentration monitor, temperature sensor (10) and pressure sensor (4) in the transparent sealed box (17) automatically record the changes in gas concentration, temperature and pressure in the box over time. The right side of the box is the blank control group. S34. When the gas concentration sensor in the left transparent sealed box no longer fluctuates, close the gas injection valve I (3) and the test ends. S35. After the test, the cemented filling material (6) sample after the flue gas was fixed was taken out. The original filling material and the cemented filling material (6) sample after the flue gas was mineralized were analyzed by XRD and SEM-EDS respectively to determine the changes in phase and surface morphology of the filling material before and after the flue gas was mineralized. S36. The CO2, SO2, and NO content of the filling material between different cross sections is determined by the gas concentration sensor (9) pre-embedded in the specimen. x The diffusion coefficient was used to obtain the CO2, SO2, and NO content inside the filling material under different injection pressures. x The extent of its spread; S37. Theoretical flue gas fixation capacity per unit mass of experimental materials obtained in step S2 m 理论烟气 Based on the pressure drop inside the transparent sealed box before and after the mineralization and storage reaction P 矿化封存 The actual amount of flue gas treated by mineralization of filling materials was obtained. m 实际烟气 : ； In the formula, P 矿化封存 It is the pressure drop inside the transparent sealed box before and after the mineralization and storage reaction; V It is the volume of gas inside a transparent, sealed box; T It is the reaction temperature; Z It is the flue gas compressibility factor, which depends on pressure and temperature; R It is the gas constant, 8.314 J / (mol·K); m 试验材料 For the quality of the test materials; S38, according to m 实际烟气 and m 理论烟气 Calculate the flue gas solidification utilization rate ξ of the cemented filling material per unit mass under different diffusion ranges: ； S4. Based on the experimental data from step S3, establish a numerical model for sealing flue gas in cemented backfill goaf, verify and analyze the flue gas migration and chemical reaction rate, and correct the flue gas solidification utilization rate ξ per unit mass of cemented backfill based on the simulation results. S5. Establish a potential formula for sealing power plant flue gas with filling materials, and calculate the amount of flue gas to be disposed of in cemented goaf areas.

2. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, In step S1, the geological data includes at least one of the volume and burial depth of the filling goaf; the physicochemical properties of the cemented filling body include at least one of the mineral composition, porosity, pore structure, and permeability.

3. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, In step S2, the theoretical flue gas fixation capacity of the cemented filling material per unit mass is... m 理论烟气 Calculate according to the following formula: ； in, m co2 , m so2 These refer to the theoretical carbon and sulfur fixation capacities per unit volume of cemented infill. w B It refers to the mass fraction of CaO, MgO, and FeO in the filling material. M B The molar masses of CaO, MgO, and FeO are given. M CO2 , M SO2 These are the molar masses of CO2 and SO2, respectively.

4. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, The gas concentration sensor includes a carbon dioxide concentration monitor (11), a sulfur dioxide concentration monitor (12), and a nitrogen concentration monitor (13).

5. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, In step S4, the step of establishing the numerical analysis for sealing flue gas in cemented goaf includes: S41. Model the underground rock, formation characteristics and flue gas reaction process using known data, including defining formation boundary conditions, key parameters of filling materials and specific locations of flue gas injection holes; S42. Set up the scenario for the mineralization and storage experiment, set up reaction factors including flue gas injection pressure, rate, and concentration, define the heterogeneous multiphase multicomponent reaction transport equation in TOUGHREACT, input the thermodynamic data of the geochemical reaction, and set the basic laws of the mineralization reaction process. S43. Discretize the time and space grids as needed, and adjust the grid size to capture key physical phenomena; select an appropriate time step to ensure the accuracy and stability of the simulation. S44. Conduct multiphase and multicomponent reaction transport simulation, fit and analyze the simulation data and experimental data, and correct the flue gas solidification utilization rate ξ of the unit mass cemented filling body.

6. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 5, characterized in that, In step S41, the geological boundary conditions include at least one of the following: coal seam burial depth, backfill height, coal face length, and advance distance. The key parameters of the backfill material include at least one of the following: density, permeability, porosity, compressive strength, and flue gas injection rate. The specific location of the flue gas injection hole includes at least one of the following: the strike distance of the borehole from the cut and the dip distance from the boundary of the working face length.

7. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 4, characterized in that, Step S44 specifically includes determining the flue gas diffusion range and reaction equilibrium time based on the TOUGHREACT numerical simulation results, and correcting the mineralization and storage efficiency of the filling material obtained from the experiment.

8. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, In step S5, the formula for the potential of the filling material to seal power plant flue gas is as follows: ； In the formula, T 烟气 To preserve the flue gas potential of power plants with filling materials, m 理论烟气 The theoretical flue gas fixation capacity per unit mass of cemented packing. ρ m For the density of the filling material, v To fill the volume of the goaf, φ For the porosity of the filling material, ξ The utilization rate of flue gas solidification for filling materials.

9. The method for calculating the amount of power plant flue gas to be disposed of in cemented backfill goaf according to claim 1, characterized in that, In step S5, the minimum flue gas disposal volume is determined based on the mineralization and sequestration flue gas test of the cemented backfill body under the condition of minimum flue gas diffusion range. T 烟气 The maximum flue gas handling capacity is derived based on the theoretical flue gas fixation capacity of the cemented filling body. T 烟气 / ξ .

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