Mine underground space responsive enhanced heat storage filling system and energy storage method

Abstract

The application provides a mine underground space responsive enhanced heat storage filling system and an energy storage method; the specific steps include: (1) coal underground space site selection; (2) preparation of filling paste; (3) arrangement of heat storage pipeline system; (4) arrangement of resistance heating system; (5) arrangement of monitoring system; (6) construction of enhanced heat storage filling system; (7) conversion, storage and utilization of valley electricity, abandoned electricity and waste heat. The application cross-fuses coal mine filling mining and deep underground space energy storage two industries, further innovates the filling mining method, fully displays the great potential of the filling body in supporting renewable energy, realizes the comprehensive utilization of coal mine solid waste and the efficient consumption of abandoned electricity, valley electricity and the like, solves the problem of energy storage utilization in the present stage of coal mine goaf, and provides key theoretical and technical support for developing new energy in the coal-bearing area and promoting the upgrading and transformation of the coal-bearing area.

Description

Technical Field

[0001] This invention relates to the field of mining engineering; and more particularly to a responsive enhanced thermal energy storage filling system and energy storage method for underground mining spaces. Background Technology

[0002] Energy storage, as a key supporting technology for the energy revolution, is urgently needed to promote the large-scale integration of renewable energy and improve the efficiency of power systems and regional energy systems. Underground space in mines, with its advantages of large volume, stable temperature, and high pressure resistance, is an ideal location for energy storage. This requires overcoming a series of fundamental theoretical and key technical challenges in energy storage in deep mine underground spaces. Currently, coal mining faces numerous pressures, including ensuring energy security, protecting the ecological environment, and reducing carbon emissions; therefore, the green and low-carbon development of coal mining is imperative. With the increasingly severe problems of coal gangue, fly ash, and other coal-based solid waste emissions and treatment, coal-based solid waste disposal has become a key factor restricting the green and efficient mining of coal. Coal-based solid waste backfilling mining technology aligns with the main research directions of green and intelligent coal mining and clean, efficient, and low-carbon utilization, and has significant technical advantages in areas such as surface subsidence control, ecological environment protection, mine solid waste disposal and utilization, and green and low-carbon emission reduction.

[0003] In recent years, backfilling mining technology has continued to develop, driven by mining production practices and the demand for backfilling functions. However, with the new opportunities and challenges brought about by industrial intelligent upgrading, deep mining, and the resource utilization of coal-based solid waste, in-depth theoretical and technical research on coal-based solid waste backfilling mining is urgently needed. For operating mines, high costs have always been a key obstacle to the widespread application of backfilling mining technology. Domestic and foreign scholars have proposed technically and economically feasible functional backfilling mining methods for new carbon reduction models in coal mining systems, expanding the backfilling functions of traditional mines and providing new paths for the transformation and upgrading of operating or abandoned mines. Enhanced regenerative thermal reflux backfilling technology for coal mine goafs effectively reduces the negative environmental impact of coal-based solid waste, while solving the problem of reusing backfilling materials after mining and after resource depletion and mine closure, providing new ideas for promoting safe, efficient, green, and low-carbon coal development and extending the life cycle of coal-bearing areas.

[0004] Current methods for energy storage using underground coal-fired power plants primarily involve converting underground spaces into energy storage facilities and designing systems to transport the required storage medium underground for storage. This includes the temporary storage of certain strategic energy sources. On the other hand, current thermal energy storage technologies mainly utilize molten salt thermal storage, which requires a large area, and its application in underground coal-fired power plants is less common. Furthermore, thermal storage using filling materials is generally low-temperature thermal storage, resulting in low energy density and relatively low thermal storage efficiency.

[0005] Among different energy storage methods, electrochemical energy storage may produce byproducts that cause serious pollution to the underground environment, while compressed air energy storage may pose risks of gas explosions or leaks and lacks a mature regulatory system. Current research on thermal energy storage using filling materials generally results in lower storage temperatures and is often developed in conjunction with geothermal energy. The filling materials mainly consist of clay, fly ash, coal gangue, or binders made from them, which cannot fully meet the demands of thermal energy storage. Therefore, there is an urgent need to develop a more economical and efficient thermal energy storage filling material and method. Summary of the Invention

[0006] The purpose of this invention is to provide a responsive enhanced thermal energy storage filling system and energy storage method for underground mining spaces.

[0007] This invention is achieved through the following technical solution:

[0008] This invention relates to a responsive enhanced thermal energy storage and filling system for underground mining space, comprising: a cable 1, a waste electricity collection system 2, a filling slurry preparation system 3, a delivery pipeline 4, an industrial waste heat storage device 5, a thermal energy extraction device 6, a generator 7, a user terminal 8, a water inlet channel 9, a water outlet channel 10, a flow meter 11, a mudstone stratum 12, a sandstone stratum 13, a stress sensor 14, a displacement sensor 15, a thermal energy extraction pipeline 16, an enhanced thermal energy storage and filling body 17, a temperature sensor 18, and a resistance wire 19.

[0009] Among them, the working end of the heat extraction pipeline 16 is located inside the enhanced heat storage filling body 17, and its other end is connected to the water inlet channel 9 and the water outlet channel 10 respectively.

[0010] Temperature sensors 18 are uniformly installed in each layer of the enhanced thermal storage filling body 17 to monitor temperature changes in real time and transmit the data to a ground data center for analysis. An overheat protection device is also installed, and based on the data analysis results, it automatically controls relevant equipment. The thermal storage temperature of this invention does not exceed 200℃ to ensure the stability of the filling body.

[0011] The top plate of the enhanced thermal storage filling body 17 is equipped with stress sensors 14 and displacement sensors 15 to monitor the stress and displacement of the top plate in real time, ensuring the stability of the surrounding rock.

[0012] On the ground, the prepared filling paste is transported via pipeline 4 to the filling area of ​​the underground reinforced thermal storage filling body 17 through the filling slurry preparation system 3. The reinforced thermal storage filling body 17 needs to fill the entire underground space and be connected to the roof to ensure the accumulation and storage of heat. The reinforced thermal storage filling body 17 needs to be consolidated and cured for at least 28 days to give it sufficient strength to support the surrounding rock and ensure the stability of the surrounding rock in the underground space.

[0013] The resistance wire 19 and the heat extraction pipeline 16 are arranged alternately at different heights.

[0014] Preferably, the working ends of the heat extraction pipe 16 are arranged in a double-layer configuration with parallel surfaces; each layer consists of multiple annular pipes arranged at equal intervals; the resistance wire 19 is disposed between adjacent annular pipes in each layer to achieve uniform heat distribution.

[0015] This invention also relates to an energy storage method for the aforementioned mine underground space responsive enhanced thermal energy storage filling system, comprising:

[0016] Step 1, Site selection for underground coal mining space;

[0017] Step 2, preparation of the filling paste;

[0018] Step 3, Arrangement of the thermal storage pipeline system;

[0019] Step 4, Arrangement of the resistance heating system;

[0020] Step 5, Monitoring system deployment;

[0021] Step 6: Construction of the enhanced thermal storage filling system;

[0022] Step 7: Conversion, storage and utilization of off-peak electricity / waste electricity / waste heat.

[0023] Preferably, the specific steps of step 1 are as follows:

[0024] Select areas with stable strata, dense lithology, no obvious faults and karst development. The distribution of suitable thermal energy storage strata from top to bottom is as follows: mudstone strata 12, sandstone strata 13, and filling area of ​​enhanced thermal energy storage infill body 17.

[0025] While ensuring the safety of the energy storage space, the system achieves sufficient heat accumulation and efficient heat transfer. The enhanced thermal storage filling body 17 is adjacent to sandstone 13 with high thermal conductivity, and at its distal end is mudstone 12 with poor thermal conductivity. This allows the heat in the enhanced thermal storage filling body 17 to be quickly and efficiently transferred to the sandstone 13, thereby improving the heat exchange efficiency between the enhanced thermal storage filling body 17 and the thermal energy extraction pipeline 16. Due to its poor thermal conductivity, the mudstone 12 effectively suppresses the dissipation of heat energy in the filling body-sandstone system, enhancing the thermal storage capacity of the thermal storage system.

[0026] Preferably, the specific steps of step 2 are as follows:

[0027] The components of the filling paste are mixed according to the following proportions:

[0028] Cement accounts for 8-10% of the total, fly ash accounts for 25-28%, gangue accounts for 38-40%, graphite nanoparticles account for 1-3%, and ceramic nanoparticles account for 1-3%.

[0029] Coal gangue is crushed and proportioned according to the Thaler scale. The coal gangue is crushed into gangue particles with diameters of 0–5 mm, 5–10 mm, 10–15 mm, and 15–20 mm, respectively, and then proportioned according to the Thaler scale. 0–5 mm accounts for 50%, 5–10 mm accounts for 21%, 10–15 mm accounts for 16%, and 15–20 mm accounts for 13%. This invention, using the above proportions, significantly improves the thermophysical properties of the filling material, achieving efficient thermal storage.

[0030] Preferably, the specific steps of step 3 are as follows:

[0031] The working end of the heat extraction pipeline 16 is pre-buried in the filling area of ​​the enhanced thermal storage filling body 17 for storing and extracting heat. The pipeline adopts a ring layout in layers, and the working end has a double-layer structure with a layer spacing of 1m. The pipeline diameter of each layer is 0.1m and the pipe spacing is 1m.

[0032] Preferably, the specific steps of step 4 are as follows:

[0033] Resistance wires 19, made of nickel-copper, are pre-installed evenly in layers within the filling area of ​​the enhanced thermal storage filling body 17. The resistance wires 19 and the thermal energy extraction pipes 16 are arranged alternately, with a 1m interval between layers. Resistance wires are installed between adjacent pipe layers to achieve uniform heat distribution. The heat generation of the resistance wires is Q = I. 2 Rt.

[0034] The power source is wind and solar power curtailment, off-peak electricity (hereinafter collectively referred to as waste electricity), etc. By controlling the current magnitude and energizing time of the resistance wire, the enhanced thermal storage filling body 17 is heated evenly to achieve thermal energy storage.

[0035] Preferably, the specific steps of step 5 are as follows:

[0036] Temperature sensors 18 are uniformly arranged in each layer of the filling area of ​​the enhanced thermal storage filling body 17 to monitor temperature changes in real time and transmit the data to a ground data center for analysis. An overheat protection device is also installed, and based on the data analysis results, the relevant equipment is automatically controlled. The thermal storage temperature of this invention does not exceed 200℃ to ensure the stability of the filling body. Stress sensors 14 and displacement sensors 15 are arranged in the top stratum above the filling area of ​​the enhanced thermal storage filling body 17 to monitor the stress and displacement of the top stratum in real time, ensuring the stability of the surrounding rock.

[0037] Preferably, the specific steps of step 6 are as follows:

[0038] The prepared filling paste is transported to the filling area of ​​the enhanced thermal storage filler 17 through the conveying pipeline 4 via the filling slurry preparation system 3 to form the enhanced thermal storage filler 17.

[0039] The enhanced thermal storage filling body 17 needs to fill the entire filling area and be connected to the top to ensure the accumulation and storage of heat; the enhanced thermal storage filling body 17 needs to be consolidated and cured for at least 28 days to give it a certain strength to support the surrounding rock and ensure the stability of the surrounding rock in the underground space.

[0040] Preferably, the specific steps of step 7 are as follows:

[0041] The waste electricity collected in the waste electricity collection system 2 is converted into stable DC electricity by an AC-DC converter and then transmitted to the well via cable 1. The current flows through the resistance wire 19 to heat the enhanced thermal storage filling body 17 and thus store the heat.

[0042] The industrial waste heat in the industrial waste heat storage device 5 is transported to the underground enhanced thermal storage filling body 17 through the thermal energy extraction pipe 16 using the thermal energy extraction device 6. The industrial waste heat circulates fully in the thermal energy extraction pipe 16, and the thermal energy is efficiently stored in the enhanced thermal storage filling body 17. Sensors installed inside the enhanced thermal storage filling body 17 monitor the changes of various parameters (temperature, strain, displacement, etc.) in real time.

[0043] A low-temperature heat extraction medium is injected along the inlet channel 9 to fully circulate and extract heat in the heat extraction pipeline 16; flow meters and temperature sensors 11 are installed in both the inlet channel 9 and the outlet channel 10 to monitor and analyze changes in fluid flow rate, velocity and temperature; based on actual numerical feedback, the parameters of the heat extraction medium injection temperature, velocity and circulation number are adjusted to ensure efficient extraction of heat energy.

[0044] After the heat extraction medium reaches the target temperature, the heat extraction equipment 6 extracts it from the ground along the water outlet channel 10 and transports it to the user end 8 for domestic heating; when the load demand of the power system exceeds the supply capacity, the heat energy is transported to the generator set to drive the generator 7 to generate electricity, supplement the power gap, and flexibly participate in the grid peak shaving.

[0045] Among them, the efficiency of heat energy extraction

[0046] Q 管道 =c 水 m 水 (T out -T in ),

[0047] Q 充填体 =c 充填体 m 充填体 (T0-T1)

[0048] In the formula: c 水 The specific heat capacity of water; m 水 The mass of circulating water in thermal energy extraction pipeline 16; T outThe temperature of the water outlet channel (10); T in The temperature of the water inlet channel 9; c 充填体 Specific heat capacity of the filling material; m 充填体 T0 represents the mass of the filling material; T1 represents the initial temperature of the enhanced thermal storage filling material 17; and T1 represents the temperature of the enhanced thermal storage filling material 17 after heat extraction.

[0049] The present invention has the following advantages:

[0050] (1) Medium and high temperature thermal storage: At present, the functional filling technology for mine thermal storage mainly adopts phase change thermal storage, which has a relatively low thermal storage temperature; while the present invention can achieve medium and high temperature thermal storage (above 150℃), with high energy density and high thermal energy storage and utilization efficiency, which is the core direction for the future development of thermal storage.

[0051] (2) Responsive Energy Storage: When the power supply is sufficient to meet the power demand, the thermal energy storage filling system involved in this invention will collect waste electricity resources and heat the filling body through resistance wires. When the power supply cannot meet the demand, the thermal energy storage filling system involved in this invention will adopt a flexible responsive operation mode according to the demand, extracting heat from the filling body to generate electricity or provide heat. This flexible responsiveness not only enhances the economic attractiveness of the thermal energy storage filling system, but also improves the overall efficiency of the system through optimized operation.

[0052] (3) Utilization of underground space in coal mines: Underground space in coal mines has the characteristics of high temperature, large volume and good stability, making it an ideal place for energy storage. After coal mining, a large amount of underground space is generated, and this space is generally not used. The method involved in this invention fills the gap in energy storage in underground space of mines by planning and designing thermal energy storage based on underground space.

[0053] (4) Enriching the connotation of filling body: The purpose of filling underground space in coal mines is generally to control ground pressure, stabilize strata and improve resource recovery rate. Based on this, the method involved in this invention improves conventional filling materials and optimizes and enhances the various heat storage properties of filling materials, making them a functional carrier for efficient heat storage in underground space.

[0054] (5) Combined heat storage mode of resistance wire and pipeline: The conventional heat storage and extraction method is carried out through thermal buried pipe. The method involved in this invention converts waste electricity into heat energy and stores it in the filling body through resistance heater, which greatly improves the heat energy conversion efficiency. At the same time, the heat energy extraction pipeline is used to store industrial waste heat and other heat energy in the filling body, realizing the effective storage and utilization of industrial waste heat. During peak electricity consumption, it can also be combined with power generation technology to fill the power gap and flexibly participate in grid peak regulation.

[0055] (6) Extending the life cycle of the mine: After coal mining, many underground spaces are left. The method involved in this invention makes full use of the underground space of the coal mine and the existing related supporting equipment to realize high-temperature thermal energy storage in the underground space of the coal mine, turning waste into treasure, extending the life cycle of the mine, and providing theoretical reference and practical examples for the development of new energy in coal-bearing areas and the promotion of mine transformation and utilization in my country. Attached Figure Description

[0056] Figure 1 This is a flowchart of an energy storage method for a mine underground space responsive enhanced thermal energy storage filling system, as described in this invention.

[0057] Figure 2 This is a schematic diagram of the structure of a mine underground space responsive enhanced thermal energy storage and filling system according to the present invention;

[0058] Figure 3 This is a schematic diagram of the thermal energy storage layer site selection in this invention;

[0059] Figure 4 This is a schematic diagram of the structure of the in-body thermal energy extraction pipeline in this invention;

[0060] Figure 5 This is a schematic diagram of the arrangement of the in-body resistance wires in this invention;

[0061] Attached diagram labels: 1. Cable; 2. Waste electricity collection system; 3. Filler slurry preparation system; 4. Conveying pipeline; 5. Industrial waste heat storage device; 6. Thermal energy extraction equipment; 7. Generator; 8. User terminal; 9. Inlet channel; 10. Outlet channel; 11. Flow meter; 12. Mudstone formation; 13. Sandstone formation; 14. Stress sensor; 15. Displacement sensor; 16. Thermal energy extraction pipeline; 17. Enhanced thermal energy storage filling body; 18. Temperature sensor; 19. Resistance wire. Detailed Implementation

[0062] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are merely further illustrations of the present invention, but the scope of protection of the present invention is not limited to the following embodiments.

[0063] Example

[0064] This embodiment relates to a responsive enhanced thermal energy storage and filling system for underground spaces in mines. See Figure 2 As shown, it includes: cable 1, waste electricity collection system 2, filling slurry preparation system 3, conveying pipeline 4, industrial waste heat storage device 5, thermal energy extraction equipment 6, generator 7, user terminal 8, water inlet channel 9, water outlet channel 10, flow meter 11, mudstone formation 12, sandstone formation 13, stress sensor 14, displacement sensor 15, thermal energy extraction pipeline 16, enhanced thermal storage filling body 17, temperature sensor 18, resistance wire 19;

[0065] Among them, the working end of the heat extraction pipeline 16 is located inside the enhanced heat storage filling body 17, and its other end is connected to the water inlet channel 9 and the water outlet channel 10 respectively.

[0066] Temperature sensors 18 are uniformly installed in each layer of the enhanced thermal storage filling body 17 to monitor temperature changes in real time and transmit the data to a ground data center for analysis. An overheat protection device is also installed, and based on the data analysis results, it automatically controls relevant equipment. The thermal storage temperature of this invention does not exceed 200℃ to ensure the stability of the filling body.

[0067] The top plate of the enhanced thermal storage filling body 17 is equipped with stress sensors 14 and displacement sensors 15 to monitor the stress and displacement of the top plate in real time, ensuring the stability of the surrounding rock.

[0068] On the ground, the prepared filling paste is transported via pipeline 4 to the filling area of ​​the underground reinforced thermal storage filling body 17 through the filling slurry preparation system 3. The reinforced thermal storage filling body 17 needs to fill the entire underground space and be connected to the roof to ensure the accumulation and storage of heat. The reinforced thermal storage filling body 17 needs to be consolidated and cured for at least 28 days to give it sufficient strength to support the surrounding rock and ensure the stability of the surrounding rock in the underground space.

[0069] The resistance wire 19 and the heat extraction pipeline 16 are arranged alternately at different heights.

[0070] Furthermore, the working ends of the thermal energy extraction pipeline 16 are arranged in a double-layered configuration with mutual parallel surfaces; see Figure 4 As shown, each layer consists of multiple annular pipes arranged at equal intervals; the resistance wire 19 is placed between adjacent annular pipes in each layer to achieve uniform heat distribution.

[0071] This embodiment also relates to the energy storage method of the aforementioned mine underground space responsive enhanced thermal energy storage filling system, see [link to relevant documentation]. Figure 1 As shown, it includes:

[0072] Step 1, selection of underground space for coal mines; select areas with stable strata, dense lithology, no obvious faults and karst development. The distribution of suitable thermal energy storage strata from top to bottom is as follows: mudstone strata 12, sandstone strata 13, and filling area of ​​reinforced thermal energy storage filling body 17.

[0073] While ensuring the safety of the energy storage space, it achieves sufficient heat accumulation and efficient heat transfer;

[0074] The influence of surrounding rock type on thermal storage effect, such as Figure 3As shown, the reinforced thermal storage filling 17 is adjacent to sandstone 13 with high thermal conductivity, and at its distal end is mudstone 12 with poor thermal conductivity. This allows heat in the reinforced thermal storage filling 17 to be quickly and efficiently transferred to the sandstone 13, thereby improving the heat exchange efficiency between the reinforced thermal storage filling 17 and the thermal energy extraction pipeline 16. The mudstone 12, due to its poor thermal conductivity, effectively suppresses the dissipation of heat energy in the filling-sandstone configuration, enhancing the thermal storage capacity of the thermal storage system.

[0075] Step 2, Preparation of the filling paste: Mix the components of the filling paste according to the following proportions:

[0076] Cement accounts for 8-10% of the total, fly ash accounts for 25-28%, gangue accounts for 38-40%, graphite nanoparticles account for 1-3%, and ceramic nanoparticles account for 1-3%.

[0077] Coal gangue is crushed and proportioned according to the Thaler scale. The coal gangue is crushed into gangue particles with diameters of 0–5 mm, 5–10 mm, 10–15 mm, and 15–20 mm, respectively, and then proportioned according to the Thaler scale. 0–5 mm accounts for 50%, 5–10 mm accounts for 21%, 10–15 mm accounts for 16%, and 15–20 mm accounts for 13%. This invention, using the above proportions, significantly improves the thermophysical properties of the filling material, achieving efficient thermal storage.

[0078] Step 3, Arrangement of thermal energy storage pipeline system: The working end of the thermal energy extraction pipeline 16 is pre-buried in the filling area of ​​the enhanced thermal energy storage filling body 17 for storing and extracting heat. The pipeline adopts a ring layout in layers, and the working end has a double-layer structure with a layer spacing of 1m; the diameter of each pipeline is 0.1m and the pipe spacing is 1m.

[0079] Step 4, Resistance Heating System Arrangement: Resistance wires 19, made of nickel-copper material, are pre-installed evenly in layers within the filling area of ​​the enhanced thermal storage filling body 17; the resistance wires 19 and the thermal energy extraction pipeline 16 are arranged alternately at intervals; see... Figure 5 As shown, the layers are spaced 1m apart, with the interlayer spacing also 1m. These layers are staggered vertically with the heat storage pipes. Resistance wires are installed between adjacent pipe layers to achieve uniform heat distribution. The heat generated by the resistance wires is Q = I. 2 Rt.

[0080] The power source is abandoned electricity, off-peak electricity (collectively referred to as waste electricity), etc. By controlling the current magnitude and energizing time of the resistance wire, the enhanced thermal storage filling body 17 is heated evenly to store thermal energy.

[0081] Step 5, Monitoring System Layout: Temperature sensors 18 are uniformly arranged in each layer of the filling area of ​​the reinforced thermal storage filling body 17 to monitor temperature changes in real time and transmit the data to a ground data center for analysis. An overheat protection device is also installed. Based on the data analysis results, relevant equipment is automatically controlled. The thermal storage temperature of this invention does not exceed 200℃ to ensure the stability of the filling body. Stress sensors 14 and displacement sensors 15 are arranged on the top plate of the filling area of ​​the reinforced thermal storage filling body 17 to monitor the stress and displacement of the top plate in real time, ensuring the stability of the surrounding rock.

[0082] Step 6, Construction of the enhanced thermal storage filling system: The prepared filling paste is transported to the filling area of ​​the enhanced thermal storage filling body 17 through the conveying pipeline 4 via the filling slurry preparation system 3 to form the enhanced thermal storage filling body 17.

[0083] The enhanced thermal storage filling body 17 needs to fill the entire filling area and be connected to the top to ensure the accumulation and storage of heat; the enhanced thermal storage filling body 17 needs to be consolidated and cured for at least 28 days to give it a certain strength to support the surrounding rock and ensure the stability of the surrounding rock in the underground space.

[0084] Step 7, Off-peak electricity / waste electricity / waste heat conversion, storage and utilization:

[0085] The waste electricity collected in the waste electricity collection system 2 is converted into stable DC electricity by an AC-DC converter and then transmitted to the well via cable 1. The current flows through the resistance wire 19 to heat the enhanced thermal storage filling body 17 and thus store the heat.

[0086] The industrial waste heat in the industrial waste heat storage device 5 is transported to the underground enhanced thermal storage filling body 17 through the thermal energy extraction pipe 16 using the thermal energy extraction device 6. The industrial waste heat circulates fully in the thermal energy extraction pipe 16, and the thermal energy is efficiently stored in the enhanced thermal storage filling body 17. Sensors installed inside the enhanced thermal storage filling body 17 monitor the changes of various parameters (temperature, strain, displacement, etc.) in real time.

[0087] A low-temperature heat extraction medium is injected along the inlet channel 9 to fully circulate and extract heat in the heat extraction pipeline 16; flow meters and temperature sensors 11 are installed in both the inlet channel 9 and the outlet channel 10 to monitor and analyze changes in fluid flow rate, velocity and temperature; based on actual numerical feedback, the parameters of the heat extraction medium injection temperature, velocity and circulation number are adjusted to ensure efficient extraction of heat energy.

[0088] After the heat extraction medium reaches the target temperature, the heat extraction equipment 6 extracts it from the ground along the water outlet channel 10 and transports it to the user end 8 for domestic heating; when the load demand of the power system exceeds the supply capacity, the heat energy is transported to the generator set to drive the generator 7 to generate electricity, supplement the power gap, and flexibly participate in the grid peak shaving.

[0089] Among them, the efficiency of heat energy extraction

[0090] Q 管道 =c 水 m 水 (T out -T in ),

[0091] Q 充填体 =c 充填体 m 充填体 (T0-T1)

[0092] In the formula: c 水 The specific heat capacity of water; m 水 The mass of circulating water in thermal energy extraction pipeline 16; T out The temperature of the water outlet channel (10); T in The temperature of the water inlet channel 9; c 充填体 Specific heat capacity of the filling material; m 充填体 T0 represents the mass of the filling material; T1 represents the initial temperature of the enhanced thermal storage filling material 17; and T1 represents the temperature of the enhanced thermal storage filling material 17 after heat extraction.

[0093] The present invention has the following advantages: (1) Medium and high temperature thermal storage: At present, the functional filling technology for mine thermal storage mainly adopts phase change thermal storage, which has a relatively low thermal storage temperature; while the present invention can achieve medium and high temperature thermal storage (above 150℃), with high energy density and high thermal energy storage and utilization efficiency, which is the core direction for the future development of thermal storage. (2) Responsive energy storage: When the power supply is sufficient to meet the power demand, the thermal storage filling system involved in the present invention will collect waste electricity resources and heat the filling body through resistance wire. When the power supply cannot meet the demand, the thermal storage filling system involved in the present invention will adopt a flexible responsive operation mode according to the demand, extract heat from the filling body to generate electricity or provide heat. The flexible responsiveness of the present invention not only enhances the economic attractiveness of the thermal storage filling system, but also improves the overall efficiency of the system through optimized operation. (3) Utilization of underground space in coal mines: Underground space in coal mines has the characteristics of high temperature, large volume and good stability, making it an ideal place for energy storage. After coal mining, a large amount of underground space is generated, and this space is generally not utilized. The method involved in this invention fills the gap in energy storage in underground space of mines by planning and designing thermal energy storage based on underground space. (4) Enriching the connotation of filling body: Filling underground space in coal mines is generally to achieve the goals of controlling ground pressure, stabilizing strata and improving resource recovery rate. The method involved in this invention improves conventional filling materials on this basis, optimizes and improves the various thermal storage performances of filling materials, and makes them functional carriers for achieving efficient thermal storage in underground space. (5) Combined thermal energy storage mode of resistance wire and pipeline: The conventional method of thermal energy storage and extraction is through thermal buried pipe. The method involved in this invention converts waste electricity into thermal energy and stores it in the filling body through resistance heater, which greatly improves the thermal energy conversion efficiency. At the same time, the thermal energy extraction pipeline is used to store industrial waste heat and other thermal energy in the filling body, realizing the effective storage and utilization of industrial waste heat. During peak electricity consumption, it can also be combined with power generation technology to fill the power gap and flexibly participate in grid peak regulation. (6) Extending the life cycle of mines: After coal mining, many underground spaces are left. The method involved in this invention makes full use of the underground space of coal mines and existing related supporting equipment to realize high-temperature thermal energy storage in the underground space of coal mines, turning waste into treasure, extending the life cycle of mines, and providing theoretical reference and practical examples for the development of new energy in coal-bearing areas and the promotion of mine transformation and utilization in my country.

[0094] The method involved in this invention significantly improves the utilization rate of coal-based solid waste resources, while enabling the efficient absorption and utilization of variable energy. During periods of low electricity demand, off-peak electricity, wind and solar power curtailment, and industrial waste heat are converted into thermal energy and stored in the backfill. When needed, this thermal energy can be extracted for power generation or heating. This invention emphasizes the importance of flexible operation of the thermal storage system, which not only enhances its deployment potential in the power system but also supports the decarbonization of the power system by providing load-tracking power generation and long-term energy storage. The method of this invention further innovates the backfill mining method, fully demonstrating the enormous potential of backfill in supporting renewable energy, solving the current problem of energy storage and utilization in coal mine goaf areas, providing key theoretical and technical support for developing new energy sources in coal-bearing areas and promoting the upgrading and transformation of coal-bearing areas, and also providing a feasible solution for achieving complete decarbonization of the power system.

[0095] The application prospects of this invention mainly focus on the following aspects:

[0096] (1) Coal underground space thermal energy storage converts industrial waste heat into storable thermal energy, which is stored in the filling body of the goaf. The huge volume and good heat storage performance of the filling body are used to realize the long-term storage of waste heat. When needed, the stored thermal energy is extracted through pipelines to solve the problems of industrial heat and residential hot water and heating.

[0097] (2) During periods of low electricity demand, resistance heat exchangers are used to convert off-peak electricity and wind and solar power into heat energy, which is stored in the filling body. When needed, the heat energy is extracted through the pipeline system. During peak electricity demand, in conjunction with power generation technology, a large amount of electricity is provided to participate in grid peak regulation and improve the reliability and flexibility of the power system.

[0098] (3) Coal mining creates numerous goaf areas, increasing the risk of surface subsidence and collapse, and damaging the surface ecological environment. This invention addresses this by promptly filling goaf areas, reducing the risk of surface subsidence and collapse, and maintaining the stability of the surface ecological environment.

[0099] (4) By developing new medium- and high-temperature thermal storage filling materials, the thermal storage performance of the filling body has been enhanced, the utilization rate of coal-based solid waste resources has been improved, and the huge potential of the filling body in supporting renewable energy has been fully demonstrated, ultimately realizing efficient thermal storage and energy storage in underground coal mine space.

[0100] (5) By storing and extracting thermal energy, enhanced thermal energy storage systems provide a sustainable energy source and reduce dependence on non-renewable resources. The extracted thermal energy can be used for residential heating to improve living comfort; at the same time, the thermal energy can also be used for power generation, participate in grid peak shaving, alleviate power load pressure, and improve the stability of the power system.

[0101] In summary, this invention has significant advantages in terms of resource recycling, environmental protection, safe production, economic benefits, technological progress, and social responsibility.

[0102] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method of energy storage for a mine underground space responsive enhanced thermal storage stowing system, characterised in that, Comprise: Step 1, coal underground space site selection; Step 2, preparation of filling paste; Step 3, heat storage pipeline system layout; Step 4, resistance heating system layout; Step 5, monitoring system layout; Step 6, enhanced thermal storage filling system construction; Step 7, valley electricity / abandoned electricity / waste heat conversion, storage and utilization; The mine underground space responsive enhanced thermal storage filling system comprises: a cable (1), a waste electricity collection system (2), a filling slurry preparation system (3), a conveying pipeline (4), an industrial waste heat storage device (5), a heat extraction device (6), a generator (7), a user end (8), an inlet water channel (9), an outlet water channel (10), a flow meter (11), a mudstone stratum (12), a sandstone stratum (13), a stress sensor (14), a displacement sensor (15), a heat extraction pipeline (16), an enhanced thermal storage filling body (17), a temperature sensor (18), and a resistance wire (19); Wherein, the working end of the heat extraction pipeline (16) is arranged inside the enhanced thermal storage filling body (17), and the other end thereof is connected with the inlet water channel (9) and the outlet water channel (10) respectively; The temperature sensor (18) is uniformly arranged in each layer of the enhanced thermal storage filling body (17), which can monitor the temperature change in real time and transmit the data to the ground data center for analysis; The stress sensor (14) and the displacement sensor (15) are arranged in the upper stratum roof of the enhanced thermal storage filling body (17), which can monitor the stress and displacement of the roof in real time and ensure the stability of the surrounding rock; The resistance wire (19) is arranged in an upper and lower staggered manner with the heat extraction pipeline (16); The working end of the heat extraction pipeline (16) is arranged in a double-layer parallel manner; each layer is arranged in a multiple annular pipeline equidistant arrangement structure; and the resistance wire (19) is arranged between adjacent annular pipelines of each layer; The specific steps of step 7 are as follows: The waste electricity collected in the waste electricity collection system (2) is converted into stable direct current by an AC-DC converter, which is then conveyed to the underground through the cable (1), and the current flows through the resistance wire (19) to heat the enhanced thermal storage filling body (17) and store heat; The industrial waste heat in the industrial waste heat storage device (5) is conveyed to the underground enhanced thermal storage filling body (17) through the heat extraction pipeline (16) by using the heat extraction device (6), the industrial waste heat is fully circulated in the heat extraction pipeline (16), the temperature is further increased, and the heat energy of the industrial waste heat is stored in the enhanced thermal storage filling body (17); The low-temperature heat extraction working medium is injected along the inlet water channel (9) to make it fully circulate in the heat extraction pipeline (16); the flow meter and the temperature sensor (18) are installed in the inlet water channel (9) and the outlet water channel (10) to monitor and analyze the fluid flow, flow rate and temperature change; according to the actual numerical feedback, the injection temperature, flow rate and circulation frequency parameters of the heat extraction working medium are adjusted to ensure the efficient extraction of heat energy; After the heat extraction medium reaches the target temperature, the heat extraction equipment (6) extracts it along the water outlet channel (10) to the ground, and delivers it to the user end (8) for heating; when the power system load demand exceeds the supply capacity, the heat is delivered to the generator set to drive the generator (7) to generate electricity, supplementing the power gap and flexibly participating in grid peak shaving.

2. The energy storage method of a mine underground space responsive augmented thermal storage stowing system as claimed in claim 1, c h a r a c t e r i s e d b y, The specific steps of step 1 are as follows: The region with stable stratum, dense lithology, no obvious fault and developed karst is selected; from top to bottom, it is in turn: mudstone stratum (12), sandstone stratum (13), and filling area of enhanced heat storage filling body (17).

3. The energy storage method of a mine underground space responsive augmented thermal storage stowing system according to claim 1, characterized in that, The specific steps of step 2 are as follows: The components of the filling paste can be mixed according to the proportion, and the proportion of each component is as follows: Cement accounts for 8-10% of the total amount, fly ash accounts for 25-28% of the total amount, gangue accounts for 38-40% of the total amount, graphite nanoparticles account for 1-3% of the total amount, and ceramic nanoparticles account for 1-3% of the total amount.

4. The energy storage method of a mine underground space responsive augmented thermal storage stowing system according to claim 1, characterized in that, The specific steps of step 3 are as follows: The working end of the heat extraction pipeline (16) is pre-buried in the filling area of the enhanced heat storage filling body (17), and the layer spacing is 1m; the pipeline diameter of each layer is 0.1m, and the pipeline spacing is 1m.

5. The energy storage method of a mine underground space responsive augmented thermal storage stowing system as claimed in claim 1, c h a r a c t e r i z e d b y, The specific steps of step 4 are as follows: The resistance wire (19) is pre-layered and uniformly installed in the filling area of the enhanced heat storage filling body (17), and the resistance wire (19) and the heat extraction pipeline (16) are arranged in an upper and lower staggered manner.

6. The energy storage method of a mine underground space responsive augmented thermal storage stowing system as claimed in claim 1, c h a r a c t e r i z e d b y, The specific steps of step 5 are as follows: Temperature sensors (18) are uniformly arranged in each layer of the filling area of the enhanced heat storage filling body (17) to monitor temperature changes in real time and transmit data to the ground data center for analysis; stress sensors (14) and displacement sensors (15) are arranged on the roof of the filling area of the enhanced heat storage filling body (17) to monitor the roof stress and displacement in real time, ensuring the stability of the surrounding rock.

7. The energy storage method of a mine underground space responsive augmented thermal storage stowing system as claimed in claim 1, c h a r a c t e r i z e d b y, The specific steps of step 6 are as follows: The prepared filling paste is delivered to the filling area of the enhanced heat storage filling body (17) through the delivery pipeline (4) by the filling slurry preparation system (3), forming the enhanced heat storage filling body (17).

8. The energy storage method of a mine underground space responsive augmented thermal storage stowing system as claimed in claim 1, c h a r a c t e r i z e d b y, In step 7, the heat extraction efficiency is as follows: ， wherein: c 水 is the specific heat capacity of water; m 水 is the mass of the circulating water in the thermal energy extraction pipeline (16); T out is the temperature of the outlet water passage (10); T in is the temperature of the inlet water passage (9); c 充填体 is the specific heat capacity of the enhanced thermal storage filling body (17); m 充填体 is the mass of the enhanced thermal storage filling body (17); T0is the initial temperature of the enhanced thermal storage filling body (17), and T1is the temperature of the enhanced thermal storage filling body (17) after heat extraction.

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