Coal mine goaf circulating cooling and partitioned grid cooling fire prevention and extinguishing method and system

Abstract

The present application relates to the technical field of mine fire prevention and extinguishing, and provides a coal mine goaf circulating cooling and partitioned grid cooling supply fire prevention and extinguishing method and system, which comprises the following steps: collecting multi-source environment data of the goaf in real time; dividing the goaf into regions of different risk levels according to a preset oxygen concentration threshold and laying out a goaf cooling supply network; constructing a closed cycle heat exchange process, continuously preparing low-temperature cryogenic medium and delivering it to the goaf cooling supply network; identifying coal spontaneous combustion risks and locating high-temperature abnormal regions; regulating and strengthening the cooling supply pipeline and implementing targeted cooling supply of different intensities; and regulating the basic cooling supply pipeline to intermittently deliver the cryogenic medium along a preset S-shaped channel. The present application not only realizes closed recovery cooling and sustainable cooling of the cryogenic medium, but also enables the cryogenic medium to be preferentially delivered to high-temperature regions as needed to realize targeted heat exchange cooling, so that the goaf fire prevention and control is sustainable, controllable and economical.

Description

Technical Field

[0001] This invention relates to the technical field of mine fire prevention and extinguishing, specifically to a method and system for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas. Background Technology

[0002] Coal resources are an important energy source in my country. After coal mining, goaf areas are formed. Under leaky air and oxygen supply conditions, the remaining coal in the goaf is prone to low-temperature oxidation and heat release, gradually accumulating temperature rise and forming oxidation zones and potential high-temperature zones. When heat dissipation is insufficient or oxidation and heat release intensify, the local temperature in the goaf may enter an accelerated oxidation stage and induce spontaneous combustion of coal, seriously threatening the safe production of coal mines.

[0003] Currently, common methods for preventing spontaneous combustion of coal in goaf areas include grouting-filling sealing, nitrogen inerting, spraying of fire inhibitors, and gel foam extinguishing agents. Grouting-filling is affected by the geometry and fracture structure of the goaf, resulting in uneven grout diffusion and coverage, and mainly focuses on oxygen isolation and sealing, leading to low cooling efficiency. Nitrogen injection can reduce oxygen concentration to some extent, but nitrogen has a low heat transfer coefficient and easily dissipates in the pore channels of the goaf, making it difficult to achieve sustained deep cooling of high-temperature areas. Fire inhibitors can inhibit coal oxidation reactions, but their effectiveness is affected by drying and migration, and their long-term flame-retardant effect in sealed goaf areas is unstable. These traditional measures rely heavily on manual experience and passive handling, making it difficult to achieve timely response and precise zoned treatment in the early stage of temperature rise in the goaf, resulting in low utilization of prevention materials and unsustainable cooling effects. Summary of the Invention

[0004] To address the problems existing in the background technology, this invention proposes a method and system for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas. The aim is to achieve closed-loop recovery and cooling of cryogenic media and sustainable cooling by constructing a closed-loop heat exchange process, combined with multi-source monitoring and intelligent control decision-making in the goaf area. Furthermore, by employing a risk-based zoning and zoned grid-based pipeline layout based on oxygen concentration ranges, and with the assistance of solenoid valve control, the cryogenic media can be preferentially transported to high-temperature areas as needed to achieve targeted heat exchange and cooling, making fire prevention and control in goaf areas sustainable, controllable, and economical.

[0005] To achieve the above objectives, the present invention adopts the following solution:

[0006] A method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas includes the following steps: Step 1: Real-time collection of multi-source environmental data in the goaf, including temperature parameters and gas concentration parameters; Step 2: Based on the gas concentration parameters, the goaf area is divided into areas with different risk levels according to the preset oxygen concentration threshold, and a goaf cooling network is deployed in the area. The goaf cooling network includes basic cooling pipelines for normal temperature maintenance and enhanced cooling pipelines for use in case of abnormal high temperature. Step 3: Construct a closed-loop heat exchange process to continuously prepare cryogenic medium and transport it to the basic cooling pipeline and / or enhanced cooling pipeline for heat exchange with the goaf cooling network. The cryogenic medium after heat exchange is returned and re-enters the closed-loop heat exchange process for recooling. Step 4: Based on the multi-source environmental data, identify the risk of spontaneous combustion of coal and locate the high-temperature anomaly area; Step 5: Based on the temperature data of the high-temperature abnormal area and a preset temperature grading threshold, adjust the enhanced cooling pipelines deployed in the area and implement targeted cooling with differentiated intensity. Step 6: Based on the overall thermal environment of the goaf, regulate the basic cooling pipelines laid in each risk area to intermittently transport cryogenic media along the preset S-shaped channel.

[0007] Optionally, in step 1, the gas concentration parameter includes one or more of carbon monoxide (CO) concentration and oxygen (O2) concentration.

[0008] Optionally, step 2 specifically includes: dividing the goaf into high-risk, medium-risk, and low-risk zones according to a preset oxygen concentration threshold, wherein areas with an oxygen concentration greater than 15% are high-risk zones, areas with an oxygen concentration greater than or equal to 10% and less than or equal to 15% are medium-risk zones, and areas with an oxygen concentration less than 10% are low-risk zones; and adopting a zoned grid-based pipe layout method based on the cooling demand of different risk zones, wherein the pipe grid density in high-risk zones is greater than that in medium-risk zones, and the pipe grid density in medium-risk zones is greater than that in low-risk zones.

[0009] Optionally, the pipeline grid density in the high-risk area is 10m×10m, the pipeline grid density in the medium-risk area is 15m×10m, and the pipeline grid density in the low-risk area is 20m×10m.

[0010] Optionally, in step 3, the closed-loop heat exchange process continuously prepares cryogenic medium through mutual heat exchange between the refrigerant circulation, water heat dissipation circulation, and cryogenic medium circulation; the refrigerant circulation uses ammonia as the refrigerant, and achieves heat absorption and release in a closed loop; the water heat dissipation circulation is used to remove the heat released by the refrigerant; the cryogenic medium circulation transports the cooled cryogenic medium to the goaf cooling network for heat exchange, and the cooled cryogenic medium is returned and exchanges heat with the refrigerant again, thus forming a closed-loop cycle of cryogenic medium preparation, transportation, heat exchange, recovery, and recooling.

[0011] Optionally, step 4 specifically includes: using a multi-algorithm fusion strategy to identify the risk of spontaneous combustion of coal, wherein the multi-algorithm fusion strategy is based on a deep learning time series model and is verified by threshold discrimination or trend discrimination; the deep learning time series model includes one or more of LSTM network, GRU network or temporal convolutional network; and determining the location of the high temperature anomaly area based on data collected by environmental sensors deployed at or near the intersection of the basic cooling pipeline and the enhanced cooling pipeline.

[0012] Optionally, step 5 includes: setting temperature grading thresholds including at least three levels; When the temperature is within the range of (60℃, 80℃), it is determined to be a critical level. The solenoid valve of the corresponding branch of the enhanced cooling pipeline in this area is controlled to open intermittently, and the flow rate of the cryogenic medium flowing to this area is adjusted to 0.2-0.4 times the rated flow rate. When the temperature is within the range of (80℃, 120℃), it is determined to be a risk level. Control the opening of the solenoid valve of the corresponding branch of the enhanced cooling pipeline in this area or open it with a high duty cycle, and adjust the flow rate of the cryogenic medium flowing to this area to 0.5-0.8 times the rated flow rate. When the temperature exceeds 120℃, it is determined to be a high-risk level. The solenoid valves of the corresponding branches of the enhanced cooling pipeline in this area are fully opened, and the flow rate of the cryogenic medium flowing to this area is adjusted to 0.9-1.2 times the rated flow rate. The branch solenoid valves of adjacent areas are also opened in conjunction to form localized enhanced cooling. Among them, the circulating power equipment for conveying cryogenic media is adjusted based on the supply and return temperature difference to match the heat absorption capacity of the cryogenic media with the current risk level.

[0013] A coal mine goaf circulation cooling and zoned grid-based cooling fire prevention and extinguishing system includes a sensing system, an intelligent control system, a closed-loop heat exchange system, and a goaf cooling network. The sensing system is used to collect multi-source environmental data of the goaf in real time, wherein the multi-source environmental data includes at least temperature parameters and gas concentration parameters. The intelligent control system is electrically connected to the sensing system and is used to receive and process the multi-source environmental data, identify the risk of spontaneous combustion of coal in the goaf and locate the high-temperature area, and output control commands. The closed-loop heat exchange system includes a refrigerant circulation unit, a water heat dissipation circulation unit, and a cryogenic medium circulation unit; wherein, the refrigerant circulation unit is used to cool the cryogenic medium; the water heat dissipation circulation unit is used to dissipate the heat generated by the refrigerant circulation unit; the cryogenic medium circulation unit and the refrigerant circulation unit exchange heat through an evaporator to prepare a low-temperature cryogenic medium and transport it to the goaf cooling network; The goaf cooling network includes a main control solenoid valve, several branch solenoid valves, goaf buried pipes, liquid supply pipelines, and liquid return pipelines. The goaf buried pipes are connected to the closed-loop heat exchange system through the liquid supply pipelines and the liquid return pipelines. The main control solenoid valve is installed on the liquid supply pipelines and the liquid return pipelines. The branch solenoid valves are installed at the branch inlets of each goaf buried pipe and are controlled by the intelligent control system to regulate the delivery of cryogenic medium to the target area. The goaf buried pipes include basic cooling pipelines for basic cooling and enhanced cooling pipelines for enhanced cooling.

[0014] Optionally, the refrigerant circulation unit includes a compressor, a condenser, an ammonia storage tank, an evaporator, an ammonia gas pipeline, and a liquid ammonia pipeline. The suction end of the compressor is connected to the refrigerant outlet of the evaporator via the ammonia gas pipeline, and the discharge end of the compressor is connected to the inlet of the condenser; the outlet of the condenser is connected to the ammonia storage tank, and the outlet of the ammonia storage tank is connected to the refrigerant inlet of the evaporator via the liquid ammonia pipeline. The cryogenic medium circulation unit includes a liquid storage tank and a water pump. The outlet of the liquid storage tank is connected to the goaf buried pipe in sequence through the water pump and the liquid supply pipeline. The goaf buried pipe is connected to the evaporator in sequence through the liquid return pipeline and the liquid storage tank. The water heat dissipation circulation unit is connected to the condenser and is used to dissipate the heat released by the condenser.

[0015] Optionally, the basic cooling pipeline includes multiple horizontal pipelines and two first longitudinal pipelines. The multiple horizontal pipelines are arranged at intervals within the goaf area, and the two first longitudinal pipelines are respectively connected to both ends of each horizontal pipeline. Multiple branch solenoid valves are provided on the first longitudinal pipelines, and each branch solenoid valve is used to control the on / off state of the corresponding horizontal pipeline. The enhanced cooling pipeline includes multiple second longitudinal pipelines, each second longitudinal pipeline is arranged at intervals above the horizontal pipelines and distributed according to the grid density of the corresponding zone. Both ends of each second longitudinal pipeline are connected to the horizontal pipelines located on the edge side, and each second longitudinal pipeline is provided with a branch solenoid valve. Environmental sensors of the sensing system are arranged at the intersection or adjacent positions of each second longitudinal pipeline and each horizontal pipeline.

[0016] The beneficial effects of this invention are as follows: This solution can maintain the overall temperature of the goaf below the critical temperature for coal spontaneous combustion for a long period of time, and intervene in hotspot areas in advance when early signs of temperature rise appear, achieving a deep-cold cooling and fire prevention effect in the goaf that is "prevention-oriented, targeted enhancement, closed-loop circulation, and long-term stability". Specifically: First, this solution constructs a closed-loop heat exchange process. Through heat exchange between the circulation of the refrigerant medium, the water cooling circulation, and the cryogenic medium circulation, combined with multi-source monitoring and intelligent control decisions in the goaf area, a low-temperature cryogenic medium is continuously prepared and transported to the basic cooling pipeline and / or enhanced cooling pipeline for heat exchange with the goaf area. The cryogenic medium after heat exchange flows back and re-enters the closed-loop heat exchange process for recooling, thus forming a closed-loop operation process of "cryogenic refrigeration - targeted cooling - heat exchange and cooling - recovery and recooling", achieving continuous and controllable cooling and fire prevention in the goaf area.

[0017] Secondly, this solution employs a risk zoning approach based on oxygen concentration ranges, deploying a cooling network within the goaf using a zoned grid-based, hotspot-density piping method. Combined with solenoid valve control, this allows cryogenic media to be prioritized and delivered to high-temperature areas for targeted heat exchange and cooling. Based on the overall thermal environment of the goaf, especially in mine scenarios with high spontaneous combustion risk and requiring long-term control, the solution regulates the basic cooling pipelines deployed in each risk area, intermittently delivering cryogenic media along pre-designed S-shaped channels. This achieves uniform coverage and cyclical delivery of the cryogenic media during long-term operation.

[0018] In addition, the system in this solution can adaptively switch between two modes: high-temperature targeted treatment mode and normalized long-term temperature maintenance mode, based on the risk status of the goaf. This significantly improves the intelligence level of coal spontaneous combustion prevention and control and the efficiency of cold energy utilization, realizing the controllability and economy of goaf fire prevention and control. Attached Figure Description

[0019] Figure 1 This is a flowchart of the fire prevention and extinguishing method of the present invention; Figure 2 This is a schematic diagram of the overall structure of the fire prevention and extinguishing system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the closed-loop heat exchange system in an embodiment of the present invention; Figure 4 This is a schematic diagram of the cooling network structure in the goaf area according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the cross-sectional structure of the buried pipe in the goaf area in an embodiment of the present invention.

[0020] The diagram is labeled as follows: 1. Sensing system; 101. Environmental sensor; 102. Data conversion unit; 2. Intelligent control system; 201. Control host; 3. Refrigerant circulation unit; 301. Compressor; 302. Condenser; 303. Ammonia storage tank; 304. Evaporator; 305. Ammonia pipeline; 306. Liquid ammonia pipeline; 4. Water cooling circulation unit; 401. Cooling fan; 5. Cryogenic medium circulation unit; 501. Liquid storage tank; 502. Water pump; 6. Phase change heat transfer material; 7. Basic cooling pipeline; 701. Horizontal pipeline; 702. First longitudinal pipeline; 8. Enhanced cooling pipeline; 801. Second longitudinal pipeline; 9. Branch solenoid valve; 10. Main control solenoid valve; 11. Liquid supply pipeline; 12. Liquid return pipeline; 13. Goaf. Detailed Implementation

[0021] To make the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the given embodiments are merely one implementation method and do not represent all embodiments.

[0022] Example 1 Combination Figure 1 This invention provides a method for circulating cooling and zoned grid-based cooling for fire prevention in coal mine goaf areas. The aim is to achieve closed-loop recycling and cooling of cryogenic media and sustainable cooling by constructing a closed-loop heat exchange process, combined with multi-source monitoring and intelligent control decision-making in the goaf area. Furthermore, it employs a risk-based zoning and grid-based pipeline layout based on oxygen concentration ranges, coupled with solenoid valve control, to prioritize the delivery of cryogenic media to high-temperature areas for targeted heat exchange and cooling, thus ensuring the fire prevention and control of the goaf area 13 is sustainable, controllable, and economical.

[0023] Specifically, it includes the following steps: Step 1, Data Acquisition: Environmental sensors 101 are deployed at key locations within the goaf 13 and adjacent roadways to collect multi-source environmental data in real time. The environmental data includes at least temperature parameters and gas concentration parameters, preferably including carbon monoxide and oxygen concentrations. The raw data signals collected by the sensors are processed by a data conversion unit 102, which performs signal conditioning, filtering and noise reduction, outlier removal, and data synchronization before transmitting the data to the control host 201, providing a foundation for subsequent risk identification and control.

[0024] Step 2, Zoned Pipeline Deployment: Based on the oxygen concentration data, the goaf 13 is divided into areas of different risk levels according to a preset oxygen concentration threshold. Specifically, the division criteria are: areas with an oxygen concentration greater than 15% are high-risk areas, areas with an oxygen concentration ≥10% and ≤15% are medium-risk areas, and areas with an oxygen concentration less than 10% are low-risk areas. To address the different cooling needs of different risk areas, a zoned grid-based, hotspot-density pipe deployment method is used to deploy the goaf cooling network within the goaf 13. As one embodiment, the grid density is 10m×10m in high-risk areas, 15m×10m in medium-risk areas, and 20m×10m in low-risk areas. The goaf cooling network includes buried pipes, with solenoid valves installed at the main pipes and the entrances of each zone branch of the buried pipes. The buried pipes include basic cooling pipelines 7 for normal temperature maintenance and enhanced cooling pipelines 8 for use during abnormal high-temperature conditions.

[0025] The basic cooling pipeline 7 is laid with a relatively sparse grid density and is mainly arranged horizontally to form a normalized cooling pipeline network covering the entire area of ​​the goaf 13; the reinforced cooling pipeline 8 is laid in the upper area of ​​the basic cooling pipeline 7 and forms a composite cooling network by intersecting with the basic cooling pipeline 7 through the densified longitudinal pipeline.

[0026] Step 3: Construct a closed-loop heat exchange process: Through heat exchange between the refrigerant circulation, water heat dissipation circulation and cryogenic medium circulation, low-temperature cryogenic medium is continuously prepared and transported to the basic cooling pipeline 7 and / or the enhanced cooling pipeline 8 to exchange heat with the goaf 13. After heat exchange, the cryogenic medium flows back and re-enters the closed-loop heat exchange process for recooling, thereby forming a closed-loop operation process of "cryogenic refrigeration - targeted cooling - heat exchange and cooling - recovery and recooling", realizing the continuous and controllable cooling and fire prevention of the goaf 13.

[0027] Specifically, ammonia is used as the refrigerant in the refrigerant cycle, sequentially completing the compression, condensation, liquid storage, throttling, and evaporation heat absorption processes to form a closed-loop ammonia refrigerant cycle: liquid ammonia evaporates and absorbs heat in evaporator 304, producing low-pressure ammonia gas. This low-pressure ammonia gas is compressed into high-pressure, high-temperature ammonia gas by compressor 301 and then enters condenser 302. In condenser 302, it exchanges heat with the cooling medium and condenses into liquid ammonia. After being pressure-stabilized by ammonia storage tank 303, the liquid ammonia re-enters evaporator 304 to complete the cycle. Water heat dissipation circulation removes the heat released by condenser 302 to the external environment. The cryogenic medium circulation uses low-temperature brine or low-temperature antifreeze gel as the cooling medium, and its supply temperature is controlled within the range of -20℃ to -30℃. Driven by the water pump 502, the cryogenic medium is transported from the storage tank 501 to the buried pipe in the goaf through the supply pipeline 11. After exchanging heat with the residual coal and surrounding rock in the goaf 13, the temperature rises. Then, it enters the evaporator 304 along the return pipeline 12 to exchange heat with the refrigerant in the wall. After being cooled again, it rejoins the circulation.

[0028] Step 4, Risk Identification and Location: Using the multi-source environmental data received in real time, a multi-algorithm fusion strategy is adopted to identify the risk of spontaneous combustion of coal and locate the high-temperature area.

[0029] The multi-algorithm fusion strategy primarily utilizes deep learning time-series models, complementing traditional algorithms. The deep learning time-series model preferably employs a temporal neural network to predict trends and identify anomalies in temperature and gas concentration time series data, effectively capturing temporal dependencies within the data. Temporal neural networks include, but are not limited to, LSTM networks, GRU networks, or temporal convolutional networks (TCNs). When data is missing or highly noisy, traditional algorithms provide supplementary support, preferably including threshold-trend joint criteria, Kalman filtering, fuzzy control, or expert rule models. These algorithms offer engineering interpretability in complex environments, ensuring stable system operation even with incomplete or disturbed data.

[0030] Specifically, the temperature and CO concentration sequences can first be smoothed using Kalman filtering or moving average. The smoothed time-series features are then input into a deep learning model to obtain future temperature trend predictions and anomaly probability outputs. Simultaneously, a threshold-trend criterion is used for engineering verification to reduce the false alarm rate. When an abnormal increase in temperature or gas concentration occurs at a grid node or intersection, data from environmental sensors 101 located at or near the intersection of the basic cooling pipeline 7 and the enhanced cooling pipeline 8 is used to accurately locate the high-temperature anomaly area. Based on the identified risk level and location mapping, the control host 201 generates the opening sequence, opening duration, and cryogenic medium circulation flow adjustment commands for the corresponding zone branch solenoid valves 9, providing a decision-making basis for subsequent targeted control.

[0031] Step 5, Targeted Treatment of High Temperature Points: Based on the real-time temperature data of the high-temperature anomaly area obtained from the location, it is matched with the preset temperature classification threshold, and targeted cooling with differentiated intensity is implemented for the enhanced cooling pipeline 8 corresponding to the area: when the temperature of the target zone is within the range of (60℃, 80℃), preventive cooling control is implemented; when the temperature is within the range of (80℃, 120℃), enhanced cooling control is implemented; when the temperature is greater than 120℃, forced targeted cooling treatment is implemented, and adjacent zones can be linked to form localized intensified cooling.

[0032] Specifically, it includes the following: When the temperature is within the range of (60℃, 80℃), it is determined to be at the critical level, indicating that the zone has entered the oxidation and temperature rise sensitive stage. Control the solenoid valve 9 (with a duty cycle of 30%) corresponding to the enhanced cooling pipeline 8 in this zone to open intermittently, and adjust the flow rate of the cryogenic medium flowing to this zone to 0.2-0.4 times the rated flow rate.

[0033] When the temperature is within the range of (80℃, 120℃), it is determined to be a risk level, indicating that the zone is in the initial stage of coal spontaneous combustion and heating. Control the opening of the branch solenoid valve 9 corresponding to the enhanced cooling pipeline 8 in this zone or open it with a high duty cycle (70% duty cycle is possible), and adjust the flow rate of the cryogenic medium flowing to this zone to 0.5-0.8 times the rated flow rate. When the temperature exceeds 120℃, it is determined to be a high-risk level, indicating that there is a significant trend of spontaneous combustion in the area and a forced cooling response is required. The solenoid valve 9 of the branch corresponding to the enhanced cooling pipeline 8 in this area is fully opened, and the flow rate of the cryogenic medium flowing to this area is adjusted to 0.9-1.2 times the rated flow rate. The branch solenoid valve 9 of the adjacent area is opened in conjunction with the temperature to form a localized intensified cooling system.

[0034] Furthermore, based on the supply-return temperature difference ΔT as the core adjustment criterion, the circulating power equipment for conveying the cryogenic medium is adaptively adjusted. Specifically, this embodiment employs adjusting the frequency of the water pump 502 to optimize the circulation velocity and flow rate of the cryogenic medium, ensuring that its heat absorption capacity per unit time matches the current risk assessment level in real time, thus achieving on-demand cooling.

[0035] Step 6, Long-term temperature maintenance under normal conditions: Based on the overall thermal environment of the goaf 13, especially in mine scenarios where the risk of spontaneous combustion in the goaf 13 is high and long-term prevention and control are required, the basic cooling pipelines 7 deployed in each risk area can be adjusted to intermittently transport cryogenic media along a preset S-shaped channel. That is, by controlling the on / off combination of each solenoid valve in the goaf cooling network, the basic cooling pipelines 7 can form a switchable S-shaped transport path to achieve uniform coverage and cyclic transport of cryogenic media under long-term operation.

[0036] In summary, using the method described in this embodiment, during long-term operation, if it is only necessary to maintain the overall thermal environment of the goaf 13 within a safe range, the intermittent cooling mode of the S-shaped path of the basic cooling pipeline 7 is activated to achieve normalized long-term temperature maintenance. When a heating trend or gas anomaly is predicted in a certain zone, the zone is switched to targeted treatment mode, and the corresponding enhanced cooling pipeline 8 branch is activated to enhance heat exchange and cooling, while maintaining the basic cooling intensity of other zones. After the temperature in the high-temperature area drops back to the safe threshold and remains stable, the corresponding branch solenoid valve 9 is closed, and the system returns to the normalized temperature maintenance state, awaiting the next control cycle.

[0037] Through the above-mentioned continuous operation mode, this method can keep the overall temperature of the goaf 13 below the critical temperature for coal spontaneous combustion for a long period of time, and intervene in hot spots in advance when early signs of temperature rise appear, so as to achieve the deep cryogenic cooling and fire prevention effect of the goaf 13 with "prevention first, targeted enhancement, closed circulation, and long-term stability".

[0038] Example 2 This embodiment provides a circulating cooling and zoned grid-based cooling and fire prevention system for coal mine goaf areas, used to implement the method described in Embodiment 1. The system can automatically identify the risk of spontaneous combustion of coal seam 13 in the goaf area and perform zoned targeted treatment and normalized long-term temperature maintenance. Figure 2 As shown, the system includes a sensing system 1, an intelligent control system 2, a closed-loop heat exchange system, and a goaf cooling network. The goaf cooling network includes a main control solenoid valve 10, several branch solenoid valves 9, a goaf buried pipe, a liquid supply pipeline 11, and a liquid return pipeline 12. The goaf buried pipe is connected to the closed-loop heat exchange system via the liquid supply pipeline 11 and the liquid return pipeline 12. The main control solenoid valve 10 is installed on the liquid supply pipeline 11 and the liquid return pipeline 12. The closed-loop heat exchange system includes a refrigerant circulation unit 3, a water heat dissipation circulation unit 4, and a cryogenic medium circulation unit 5.

[0039] Specifically, the sensing system 1 is deployed at key locations in the goaf 13 and its adjacent roadway areas to collect multi-source environmental data such as temperature, CO, and O2. The sensing system 1 comprises multiple environmental sensors 101 and a data conversion unit 102. The environmental sensors 101 are deployed at or near the intersection of the basic cooling pipeline 7 and the enhanced cooling pipeline 8 to accurately reflect temperature and gas changes in the grid area. The data collected by the environmental sensors 101 is preprocessed by the data conversion unit 102 and then uploaded to the intelligent control system 2.

[0040] Specifically, the intelligent control system 2 includes a control host 201, which is electrically connected to the sensing system 1, receives and processes multi-source environmental data, identifies the risk of spontaneous combustion of coal in the goaf 13 and locates the high-temperature area, and outputs control commands according to the preset control strategy.

[0041] Furthermore, the control commands include at least the opening sequence, opening duration, and cryogenic medium circulation flow rate adjustment commands sent to each branch solenoid valve 9. The control host 201 has a built-in multi-algorithm fusion identification module and a graded control decision module, which can automatically generate a zoned cooling strategy based on temperature graded thresholds, and perform closed-loop correction on the operating frequency of the water pump 502 based on the supply and return temperature difference ΔT, the temperature drop rate, and the predicted trend deviation to ensure that the heat absorption capacity of the cryogenic medium matches the risk level, and returns to the monitoring state after the control cycle ends to enter the next control cycle.

[0042] Specifically, the closed-loop heat exchange system achieves closed-loop output and recovery of the cryogenic medium through heat exchange between the refrigerant circulation unit 3, the water heat dissipation circulation unit 4, and the cryogenic medium circulation unit 5. This significantly reduces the consumption of fire-fighting materials and improves the utilization rate of cooling capacity. Furthermore, as... Figure 3As shown, the refrigerant circulation unit 3 includes a compressor 301, a condenser 302, an ammonia storage tank 303, an evaporator 304, an ammonia gas pipeline 305, and a liquid ammonia pipeline 306. The suction end of the compressor 301 is connected to the refrigerant outlet of the evaporator 304 via the ammonia gas pipeline 305, and its discharge end is connected to the inlet of the condenser 302. The outlet of the condenser 302 is connected to the ammonia storage tank 303, and the outlet of the ammonia storage tank 303 is connected to the refrigerant inlet of the evaporator 304 via the liquid ammonia pipeline 306, forming a closed-loop ammonia refrigerant circulation circuit. The refrigerant absorbs heat and evaporates in the evaporator 304, and releases heat and condenses in the condenser 302.

[0043] The cryogenic medium circulation unit 5 includes a storage tank 501 and a water pump 502. The cryogenic medium is preferably low-temperature brine or low-temperature antifreeze gel, with a supply temperature of -20°C to -30°C. Driven by the water pump 502, it flows out of the storage tank 501 and is transported to the buried pipe in the goaf via the supply pipeline 11. After heat exchange, the cryogenic medium returns to the evaporator 304 along the return pipeline 12, where it undergoes indirect heat exchange with the refrigerant. After being cooled again, it re-enters the circulation, realizing the recovery and re-cooling of the cryogenic medium.

[0044] The water heat dissipation circulation unit 4 is connected to the condenser 302 for heat exchange, and is used to discharge the heat released by the condenser 302 to the external environment. The water heat dissipation circulation unit 4 is connected to a heat dissipation fan 401, which performs forced heat dissipation on the condenser 302 or its heat dissipation components to maintain stable condensation pressure and ensure continuous operation of refrigerant circulation.

[0045] Specifically, the buried pipes in the goaf are laid out in a grid-like manner according to the oxygen concentration threshold, including a basic cooling pipe 7 for basic cooling and an enhanced cooling pipe 8 for enhanced cooling. The basic cooling pipe 7 is used for basic cooling and uniform temperature maintenance during long-term operation. By opening and closing the branch solenoid valves 9, an S-shaped delivery path can be formed, allowing the cooling medium to cover multiple grid units. The enhanced cooling pipe 8 is laid in the upper part of the grid area or at high-temperature risk points, and is used for targeted enhanced heat exchange when high-temperature anomalies occur. Each branch solenoid valve 9 is set at the inlet of the corresponding zone branch and is controlled by the intelligent control system 2. It can be opened directionally according to the risk positioning results, so that the cryogenic medium preferentially enters the high-temperature heat exchange pipe of the target area to achieve precise cooling.

[0046] As one example, such as Figure 4 , Figure 5As shown, the basic cooling pipeline 7 includes multiple horizontal pipelines 701 and two first longitudinal pipelines 702. The multiple horizontal pipelines 701 are arranged at intervals within the goaf 13, and the two first longitudinal pipelines 702 are respectively connected to both ends of each horizontal pipeline 701. Multiple branch solenoid valves 9 are provided on each of the first longitudinal pipelines 702, and each branch solenoid valve 9 is used to control the on / off state of the corresponding horizontal pipeline 701. The enhanced cooling pipeline 8 includes multiple second longitudinal pipelines 801, each second longitudinal pipeline 801 spaced apart. The second longitudinal pipes 801 are arranged above the transverse pipes 701 and distributed according to the grid density of the corresponding zones. Both ends of each second longitudinal pipe 801 are connected to the transverse pipes 701 located on the edge side, and each second longitudinal pipe 801 is provided with a branch solenoid valve 9. The environmental sensor 101 of the sensing system 1 is arranged at the intersection or adjacent position of each second longitudinal pipe 801 and each transverse pipe 701, so that the sensor can better reflect the temperature and gas changes in the grid area, so as to quickly locate the high temperature area.

[0047] As one embodiment, to enhance the heat exchange effect of the goaf 13, the goaf buried pipe adopts a corrosion-resistant metal pipe with an outer diameter of 32-63 mm. The liquid supply line 11 and the liquid return line 12 can be expanded to DN65-DN100 according to the system flow rate. In order to take into account the safety and reliability of the pressure environment of the goaf 13, the liquid supply line 11 and the liquid return line 12 are preferably made of low carbon steel seamless steel pipe or welded steel pipe, and the pipe wall thickness should not be less than 4.5 mm. The flow velocity of the cryogenic medium in the goaf buried pipe is preferably 0.6-1.5 m / s, and the flow velocity in the liquid supply line 11 and the liquid return line 12 is preferably 1.5-2.0 m / s, so as to ensure that the cooling capacity and pressure loss are within a reasonable range and meet the requirements of continuous heat exchange.

[0048] Alternatively, as a preferred option, a phase change heat transfer material 6, such as inorganic salt hydrates, paraffin waxes, or composite phase change materials, can be placed on the outside of the buried pipe in the goaf. Graphite powder or metal fillers can be added to improve thermal conductivity. The thickness of the phase change heat transfer material 6 is 2-3 times the pipe diameter. When the temperature in the goaf 13 rises, it absorbs heat and undergoes a phase change, forming a thermal buffer layer that slows down the temperature recovery rate and improves targeted cooling efficiency.

[0049] In this embodiment, when the system is working, the sensing system 1 collects environmental data in real time and uploads it to the intelligent control system 2; the control host 201 determines whether there is a risk of spontaneous combustion through a risk identification algorithm. If there is, it locates the high-temperature area and generates a corresponding cooling strategy; then it controls the main control solenoid valve 10 and the corresponding branch solenoid valve 9 to open, and at the same time adjusts the frequency of the water pump 502 to deliver the cryogenic medium to the target area for enhanced heat exchange; the cryogenic medium after heat exchange returns to the closed-loop heat exchange system for cooling and reuse; after the temperature drops to a safe range, the control host 201 closes the branch solenoid valve 9, and the system switches to low-power temperature maintenance or standby mode, waiting for the next control cycle.

[0050] The system mainly includes two operating modes: high-temperature point targeted treatment mode and normalized long-term temperature maintenance mode, which can be adaptively switched according to the risk status of goaf 13.

[0051] The process of the high-temperature point targeted treatment mode is as follows: When an abnormal temperature or CO occurs in a certain cross-region, the control host 201 outputs a high-temperature point targeted treatment command. If the system is not started, the main control solenoid valve 10 is opened first to connect the goaf cooling network with the closed-loop heat exchange system; if the system is in long-term temperature maintenance operation, the branch solenoid valve 9 corresponding to the high-temperature point is opened directly, allowing the cryogenic medium to preferentially enter the enhanced cooling pipeline 8 of the target zone to achieve enhanced heat exchange and cooling. During this process, the control host 201 can also dynamically adjust the opening duration or opening ratio of the branch solenoid valve 9 according to the temperature and gas change trend of the high-temperature point to avoid excessive waste of resources. When it is determined that the temperature of the zone has fallen back to the safe threshold and remained stable, the control host 201 closes the corresponding branch solenoid valve 9 and switches the system to low-power temperature maintenance or standby state, thereby completing the targeted treatment of the high-temperature abnormal area.

[0052] The normalized long-term temperature maintenance mode process is as follows: Based on risk identification and trend prediction, the control host 201 prioritizes maintaining the overall thermal environment of the goaf 13 within a safe range. When the temperature of each zone in the goaf 13 is below the safe threshold, the control host 201 controls the compressor 301 to operate at a low load, so that the evaporator 304 maintains the temperature of the cryogenic medium near the lower limit of the set range, and implements intermittent cooling control on the basic cooling pipeline 7, so that the cryogenic medium covers multiple zone grid units along the preset S-shaped channel, achieving basic temperature maintenance and uniform cooling of the goaf 13. When a heating trend or abnormal gas growth is predicted in a certain zone, the control host 201 switches the zone to the targeted treatment branch, prioritizes opening the corresponding branch solenoid valve 9, so that the cryogenic medium enters the enhanced cooling pipeline 8 of that zone for enhanced heat exchange and cooling, while maintaining the basic cooling intensity for other zones.

[0053] In summary, the system can adaptively switch between two modes: high-temperature targeted treatment mode and normalized long-term temperature maintenance mode, based on the risk status of the goaf area, significantly improving the intelligence level of coal spontaneous combustion prevention and control and the efficiency of cold energy utilization.

[0054] The specific embodiments of the present invention have been described in detail above with reference to the figures, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas, characterized in that, Includes the following steps: Step 1: Real-time collection of multi-source environmental data, including temperature parameters and gas concentration parameters, from the goaf (13); Step 2: Based on the gas concentration parameters, the goaf (13) is divided into areas with different risk levels according to the preset oxygen concentration threshold, and a goaf cooling network is set up in the area; the goaf cooling network includes a basic cooling pipeline (7) for normal temperature maintenance, and an enhanced cooling pipeline (8) for use in case of abnormal high temperature. Step 3: Construct a closed-loop heat exchange process, continuously prepare cryogenic medium and transport it to the basic cooling pipeline (7) and / or the enhanced cooling pipeline (8) for heat exchange with the goaf cooling network. The cryogenic medium after heat exchange is returned and re-enters the closed-loop heat exchange process for re-cooling. Step 4: Based on the multi-source environmental data, identify the risk of spontaneous combustion of coal and locate the high-temperature anomaly area; Step 5: Based on the temperature data of the high-temperature abnormal area and a preset temperature grading threshold, adjust the enhanced cooling pipeline (8) laid in the area and implement targeted cooling with differentiated intensity. Step 6: Based on the overall thermal environment of the goaf (13), regulate the basic cooling pipelines (7) laid in each risk area so that they intermittently transport cryogenic media along the preset S-shaped channel.

2. The circulating cooling and zoned grid-based cooling and fire suppression system for coal mine goaf areas according to claim 1, characterized in that: In step 1, the gas concentration parameter includes one or more of carbon monoxide (CO) concentration and oxygen (O2) concentration.

3. The method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas according to claim 1, characterized in that, Step 2 specifically includes: dividing the goaf (13) into high-risk, medium-risk and low-risk areas according to the preset oxygen concentration threshold, wherein the area with an oxygen concentration greater than 15% is the high-risk area, the area with an oxygen concentration greater than or equal to 10% and less than or equal to 15% is the medium-risk area, and the area with an oxygen concentration less than 10% is the low-risk area; and based on the cooling demand of different risk areas, adopting a zoned grid-based pipe layout method, wherein the pipe grid density of the high-risk area is greater than that of the medium-risk area, and the pipe grid density of the medium-risk area is greater than that of the low-risk area.

4. The method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas according to claim 3, characterized in that: The pipeline grid density is 10m×10m in the high-risk area, 15m×10m in the medium-risk area, and 20m×10m in the low-risk area.

5. A method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas according to claim 1, characterized in that: In step 3, the closed-loop heat exchange process continuously prepares cryogenic medium through mutual heat exchange between the refrigerant circulation, water heat dissipation circulation, and cryogenic medium circulation. The refrigerant circulation uses ammonia as the refrigerant, which circulates in a closed loop to absorb and release heat. The water heat dissipation circulation is used to remove the heat released by the refrigerant. The cryogenic medium circulation transports the cooled cryogenic medium to the goaf cooling network for heat exchange. The cooled cryogenic medium is then returned and exchanges heat with the refrigerant again, thus forming a closed-loop cycle of cryogenic medium preparation, transportation, heat exchange, recovery, and recooling.

6. A method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas according to claim 1, characterized in that, Step 4 specifically includes: using a multi-algorithm fusion strategy to identify the risk of spontaneous combustion of coal, the multi-algorithm fusion strategy mainly using a deep learning time series model, and combined with threshold discrimination or trend discrimination for verification; the deep learning time series model includes one or more of LSTM network, GRU network or temporal convolutional network; and based on the data collected by environmental sensors (101) deployed at the intersection or adjacent location of the basic cooling pipeline (7) and the enhanced cooling pipeline (8), the location of the high temperature abnormal area is determined.

7. A method for circulating cooling and zoned grid-based cooling for fire prevention and extinguishing in coal mine goaf areas according to claim 1, characterized in that, Step 5 includes: setting temperature grading thresholds including at least three levels; When the temperature is within the range of (60℃, 80℃), it is determined to be a critical level. The branch solenoid valve (9) corresponding to the enhanced cooling pipeline (8) in this area is controlled to open intermittently, and the flow rate of the cryogenic medium flowing to this area is adjusted to 0.2-0.4 times the rated flow rate. When the temperature is within the range of (80℃, 120℃), it is determined to be a risk level. Control the opening of the branch solenoid valve (9) of the enhanced cooling pipeline (8) in this area or open it with a high duty cycle, and adjust the flow rate of the cryogenic medium flowing to this area to 0.5-0.8 times the rated flow rate. When the temperature is greater than 120℃, it is judged as a high-risk level. The branch solenoid valve (9) corresponding to the enhanced cooling pipeline (8) in this area is fully opened, and the flow rate of the cryogenic medium flowing to this area is adjusted to 0.9-1.2 times the rated flow rate. The branch solenoid valve (9) of the adjacent area is opened in conjunction to form localized intensified cooling. Among them, the circulating power equipment for conveying cryogenic media is adjusted based on the supply and return temperature difference to match the heat absorption capacity of the cryogenic media with the current risk level.

8. A circulating cooling and zoned grid-based cooling and fire suppression system for coal mine goaf areas, used to implement the method described in any one of claims 1-7, characterized in that, The system includes a sensing system (1), an intelligent control system (2), a closed-loop heat exchange system, and a goaf cooling network. The sensing system (1) is used to collect multi-source environmental data of the goaf (13) in real time, wherein the multi-source environmental data includes at least temperature parameters and gas concentration parameters; The intelligent control system (2) is electrically connected to the sensing system (1) to receive and process the multi-source environmental data, identify the risk of spontaneous combustion of coal in the goaf (13) and locate the high-temperature area, and output control commands. The closed-loop heat exchange system includes a refrigerant circulation unit (3), a water heat dissipation circulation unit (4), and a cryogenic medium circulation unit (5); wherein, the refrigerant circulation unit (3) is used to cool the cryogenic medium; the water heat dissipation circulation unit (4) is used to discharge the heat generated by the refrigerant circulation unit (3); the cryogenic medium circulation unit (5) and the refrigerant circulation unit (3) exchange heat through an evaporator (304) to prepare a low-temperature cryogenic medium and transport it to the goaf cooling network; The goaf cooling network includes a main control solenoid valve (10), several branch solenoid valves (9), goaf buried pipes, liquid supply pipes (11), and liquid return pipes (12). The goaf buried pipes are connected to the closed-loop heat exchange system through the liquid supply pipes (11) and the liquid return pipes (12). The main control solenoid valve (10) is installed on the liquid supply pipes (11) and the liquid return pipes (12). The branch solenoid valves (9) are installed at the branch inlets of each goaf buried pipe and are controlled by the intelligent control system (2) to regulate the delivery of cryogenic medium to the target area. The goaf buried pipes include a basic cooling pipe (7) for basic cooling and an enhanced cooling pipe (8) for enhanced cooling.

9. A coal mine goaf circulating cooling and zoned grid-based cooling and fire suppression system according to claim 8, characterized in that, The refrigerant circulation unit (3) includes a compressor (301), a condenser (302), an ammonia storage tank (303), an evaporator (304), an ammonia gas pipeline (305), and a liquid ammonia pipeline (306). The suction end of the compressor (301) is connected to the refrigerant outlet of the evaporator (304) through the ammonia gas pipeline (305), and the discharge end of the compressor (301) is connected to the inlet of the condenser (302). The outlet of the condenser (302) is connected to the ammonia storage tank (303), and the outlet of the ammonia storage tank (303) is connected to the refrigerant inlet of the evaporator (304) through the liquid ammonia pipeline (306). The cryogenic medium circulation unit (5) includes a liquid storage tank (501) and a water pump (502). The outlet of the liquid storage tank (501) is connected to the goaf buried pipe in sequence through the water pump (502) and the liquid supply pipeline (11). The goaf buried pipe is connected to the evaporator (304) in sequence through the return liquid pipeline (12) and the liquid storage tank (501). The water heat dissipation circulation unit (4) is connected to the condenser (302) and is used to discharge the heat released by the condenser (302).

10. A coal mine goaf circulating cooling and zoned grid-based cooling and fire suppression system according to claim 9, characterized in that, The basic cooling pipeline (7) includes multiple horizontal pipelines (701) and two first longitudinal pipelines (702). The multiple horizontal pipelines (701) are arranged at intervals within the goaf (13), and the two first longitudinal pipelines (702) are respectively connected to the two ends of each horizontal pipeline (701). Multiple branch solenoid valves (9) are provided on the first longitudinal pipelines (702), and each branch solenoid valve (9) is used to control the opening and closing of the corresponding horizontal pipeline (701). The enhanced cooling pipeline (8) includes multiple second longitudinal pipelines (701, 702 ... Each of the second longitudinal pipes (801) is arranged at intervals above the transverse pipe (701) and distributed according to the grid density of the corresponding partition. Both ends of each of the second longitudinal pipes (801) are connected to the transverse pipe (701) located on the edge side, and each of the second longitudinal pipes (801) is provided with a branch solenoid valve (9). At the intersection or adjacent position of each of the second longitudinal pipes (801) and each of the transverse pipes (701), an environmental sensor (101) of the sensing system (1) is arranged.

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