Hidden fire source control device and method

Abstract

The hidden fire source control device comprises a seamless steel pipe, a liquid CO2 storage tank, a foaming material storage tank and a stabilizer storage tank, an effect applying opening is formed in the tail end of the seamless steel pipe, a self-excitation bubble head is arranged in the seamless steel pipe, and a bent pipeline section is arranged at one end of the self-excitation bubble head; the bent pipeline section is communicated with a liquid CO2 storage tank and a stabilizer storage tank through a liquid CO2 conveying pipeline and an injection pipeline, a phase change control unit and a static mixing device are sequentially arranged on the liquid CO2 conveying pipeline, and the static mixing device is communicated with a foaming material storage tank through the injection pipeline; the hidden fire source prevention and treatment device further comprises a cell structure monitoring module, a fire area prevention and treatment effect monitoring module and a ground monitoring center. The hidden fire source prevention and control method comprises the steps of drilling construction, CO2 conveying and phase change, mixed foaming, foaming and prevention and monitoring and feedback. According to the invention, high-efficiency covering and cooling of a hidden fire source can be realized, coal cracks are filled, air is separated, and coal oxidation and recombustion are inhibited.

Description

Technical Field

[0001] The invention belongs to the technical field of underground coal mine safety, and in particular relates to a hidden fire source prevention and control device and method. Background Art

[0002] In the process of coal mining, hidden fire sources are a major hidden danger that seriously threatens mine safety. The main causes of its formation include spontaneous combustion of coal and oxidation of coal left in the goaf. After coal mining, the coal left in the goaf will slowly oxidize under suitable temperature, humidity and ventilation conditions. If the heat cannot be dissipated in time, it will spontaneously ignite when the temperature reaches the ignition point of coal, forming a hidden fire source.

[0003] Traditional methods of preventing and controlling hidden fire sources have many shortcomings. For example, the water injection fire extinguishing method is limited by the permeability of water. For deep fire sources or those blocked by cracks, it is difficult for water to effectively reach the fire source; although the grouting fire extinguishing method can cover a certain range, it may not be able to completely fill the ignition channel for highly hidden fire sources, and it is easy to cause pollution to the underground environment; chemical fire extinguishing agents are expensive and may have adverse effects on the underground environment and personnel health. In addition, these traditional methods have limited fire extinguishing effects when faced with complex geological conditions and hidden fire sources that are difficult to determine their locations, and cannot effectively ensure safe production in coal mines. Summary of the invention

[0004] The object of the present invention is to provide a hidden fire source prevention and control device and method, which can realize the high-efficiency covering and cooling of hidden fire sources, fill coal body cracks, isolate air, and inhibit coal oxidation and re-ignition.

[0005] To achieve the above object, the present invention provides a concealed fire source prevention device, comprising a seamless steel pipe, liquid CO 2 Storage tanks, foam material storage tanks and stabilizer storage tanks, liquid CO 2 The storage tank, foaming material storage tank and stabilizer storage tank are arranged outside the front end of the seamless steel pipe. The end of the seamless steel pipe is provided with an effect application port. A self-exciting bubble head is provided in the seamless steel pipe near the effect application port. A curved pipe section is provided at the end of the self-exciting bubble head away from the effect application port.

[0006] Liquid CO passes through the curved pipe section 2 Pipeline and liquid CO 2 The storage tank is connected to the liquid CO in the seamless steel pipe. 2 A phase change control unit and a static mixing device are sequentially arranged on the delivery pipeline toward the effect application port. The static mixing device is connected to the foaming material storage tank through an injection pipeline. An injection pump is arranged on the injection pipeline.

[0007] The front end of the curved pipe section and the liquid CO 2A stabilizer inlet is provided at the connection of the delivery pipeline, and is connected to the stabilizer storage tank through an injection pipeline, and a micro-injection pump is provided on the injection pipeline;

[0008] Concealed fire source prevention and control devices also include:

[0009] Cell structure monitoring module, used to monitor the stability of cell structure during foaming process;

[0010] Fire area prevention and control effect monitoring module, used to monitor underground temperature and gas concentration information;

[0011] The ground monitoring center is used to receive feedback from the pore structure monitoring module and the fire area prevention and control effect monitoring module for centralized control or alarm.

[0012] As a further solution of the present invention: the phase change control unit includes a pressure regulating unit and a temperature regulating unit. The pressure regulating unit includes a pressure pump, a regulating valve and a pressure sensor arranged in sequence along the fluid conveying direction. The temperature regulating unit is arranged after the pressure regulating unit along the fluid conveying direction, and includes a heating device, a cooling device and a phase change temperature sensor.

[0013] As a further embodiment of the present invention: liquid CO 2 Liquid level gauges are installed on both the storage tank and the foam material storage tank. 2 A pressure gauge and a safety valve are also installed on the storage tank, a stirring device is installed in the foaming material storage tank, and a feeding port with a sealing cover is arranged at the top of the foaming material storage tank.

[0014] As a further embodiment of the present invention: liquid CO 2 The transmission pipeline adopts a multi-layer composite structure, including an outer anti-corrosion and pressure-resistant protective layer, an intermediate thermal insulation layer and an inner layer of low-temperature and chemical corrosion-resistant materials. The pipelines are connected by a combination of flanges and sealing gaskets, and fixed by brackets and hangers. The connecting parts are provided with expansion margins.

[0015] As a further solution of the present invention: a static mixing device is provided with twisted blades or spiral blades for achieving rapid and uniform mixing of multiple fluids.

[0016] As a further solution of the present invention: the pore structure monitoring module obtains the pore structure information by at least one of microstructure monitoring, physical property monitoring and optical monitoring.

[0017] A method for preventing and controlling hidden fire sources, based on the above-mentioned hidden fire source prevention and control device, comprises:

[0018] The drilling arrangement system is used to plan and construct drilling holes according to the underground geological conditions of the coal mine and the suspected hidden fire source area, so that the drilling holes can reach the target area;

[0019] CO2 Transport and phase change control systems, including liquid CO 2 Storage tank, liquid CO 2 The transmission pipeline and phase change control unit are used to transfer liquid CO 2 The phase change control unit is delivered to the end of the drill hole and controls its phase change to produce an impact effect;

[0020] The foaming material injection system includes a foaming material, a foaming material storage tank, an injection pump, an injection pipeline, a nucleating agent, a micro-injection pump and an injection pipeline; it is used to inject the foaming material into the end of the borehole, and the foaming material and liquid CO 2 Supercritical CO formed by phase transition 2 After being mixed in a static mixing device, it enters the ambient coal body through a self-excited bubble head;

[0021] The monitoring and feedback system includes a pore structure monitoring module and a fire zone prevention and control effect monitoring module; the pore structure monitoring module is used to monitor the stability of the pore structure during the foaming process; the fire zone prevention and control effect monitoring module is used to monitor the underground temperature and gas concentration information; the liquid CO is controlled based on the monitoring data feedback. 2 Delivery volume, phase change conditions, foaming material, nucleating agent and stabilizer injection amount;

[0022] The specific steps are as follows:

[0023] Drilling construction: Use downhole drilling equipment to construct according to the designed drilling arrangement plan, monitor the drilling direction, depth and geological conditions in real time to ensure that the drilling reaches the target area accurately;

[0024] CO 2 Transport and phase change: liquid CO 2 Through liquid CO 2 The pipeline is sent to the end of the borehole, and the phase change control unit adjusts the pressure and temperature parameters to make the liquid CO 2 Phase change occurs to obtain supercritical CO 2 ;

[0025] Mixed foaming: The foaming material and nucleating agent flow into the static mixing device at the end of the borehole through the injection pipe under the action of the injection pump, and mix with the supercritical CO regulated by the phase change control unit. 2 Mixing to form foaming material / supercritical CO 2 A homogeneous system, which continues to flow along the pipeline toward the effect application port and the high-temperature and low-pressure coal body;

[0026] Foaming and prevention: Foaming materials / supercritical CO 2 The homogeneous system will undergo phase change again or maintain a supercritical state due to changes in the temperature and pressure environment of the self-excited bubble head, the effect port and the coal body itself, that is, part of the supercritical CO 2Phase change impact foaming promotes the formation of pore structure. The foamed material directly reduces the temperature of the fire zone. The other part of the foaming material / supercritical CO that has not undergone phase change 2 The system directly enters the ambient coal, and the supercritical CO 2 It can quickly penetrate into the cracks and pores of the coal body by virtue of its own molecular movement ability, and also drive the foaming material into these parts. Finally, the phase change impact increases the pores, driving the foaming material to fill the cracks and pores of the coal body, isolating the air and preventing coal oxidation to achieve the purpose of preventing and controlling hidden fire sources.

[0027] Monitoring and feedback: The liquid CO in the phase change control unit is monitored in real time through the phase change temperature sensor and pressure sensor in the phase change control unit. 2 The temperature and pressure of the fire source can be adjusted in order to make adjustments; the pore structure monitoring module is used to monitor the state of the pore structure formed during the foaming process in real time, so as to accurately control the addition of stabilizers through a micro-injection pump; the fire area prevention and control effect monitoring module is to set a borehole temperature sensor and a gas concentration sensor in the coal body around the end of the borehole to monitor the changes in the borehole ambient temperature and various gas concentration parameters in real time, reflect the combustion and extinction status of the hidden fire source, evaluate the prevention and control effect based on the monitoring data feedback, and alarm or adjust the liquid CO when necessary. 2 Conveying amount, phase change conditions, foaming material, nucleating agent and stabilizer injection amount.

[0028] As a further solution of the present invention: the foaming material is one of a polyurethane foaming material containing ammonium polyphosphate flame retardant, a phenolic foaming material composited with melamine pyrophosphate and pentaerythritol, and an expandable graphite composite melamine foaming material.

[0029] As a further solution of the present invention: the nucleating agent is premixed with the foaming material or directly added and stirred evenly by a stirring device.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) Fire extinguishing efficiency:

[0032] The present invention utilizes liquid CO 2 The impact produced by the phase change can rapidly cause the foaming material to foam and drive the foaming material deep into the location of the hidden fire source. The foaming system formed quickly reduces the temperature of the fire zone, forms a stable fire barrier, and fills the pores of the coal body to isolate the air. Compared with traditional methods, it can stop the spread of fire more quickly and effectively suppress re-ignition.

[0033] (2) Adaptability to complex environments:

[0034] Through the precise drilling layout system, the position, angle and depth of the drilling holes can be flexibly adjusted according to different geological conditions (such as faults, folds, roofs and floors of different rock types, etc.) and the characteristics of suspected hidden fire source areas to achieve coverage of various complex underground environments.

[0035] CO 2 The transportation and phase change control system can adapt to the complex environment downhole and realize liquid CO 2 Stable phase change. Moreover, the foaming material injection system can make the foaming material effectively foam and play a role in complex geological structure areas, such as easily broken roofs and karst development areas, according to different geological stress conditions and coal body fissure characteristics.

[0036] (3) Environmental protection and safety:

[0037] The liquid CO used in the present invention 2 It is an environmentally friendly substance, non-toxic and harmless, and will not pollute the underground environment. The selected foaming material has also been carefully designed and will not produce harmful substances during use.

[0038] During the entire prevention and control process, the underground environmental parameters are monitored in real time through the monitoring and feedback system to ensure the safety of the operation process, and no new safety hazards such as explosions and poisoning will be caused by the prevention and control process itself. Moreover, after the fire is extinguished, the material will not cause long-term pollution to the air and water resources underground, and can achieve high-efficiency coverage and cooling of hidden fire sources, fill coal cracks, isolate air, inhibit coal oxidation and re-ignition, and expand new ideas for fine prevention and control of fire sources in large areas of hidden areas underground. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of the concealed fire source prevention device of the present invention;

[0040] Figure 2 This is a schematic diagram for the management of hidden fire sources.

[0041] In the figure: 1. seamless steel pipe, 2. injection pipe, 3. micro injection pump, 4. stabilizer storage tank, 5. foaming material storage tank, 6. feeding port, 7. nucleating agent, 8. stirring device, 9. injection pipe, 10. injection pump, 11. pressure gauge, 12. safety valve, 13. liquid level gauge, 14. liquid CO 2 Storage tank, 15, liquid CO 2 Conveying pipeline, 16. Phase change control unit, 17. Pressure pump, 18. Control valve, 19. Pressure sensor, 20. Heating device, 21. Phase change temperature sensor, 22. Cooling device, 23. Static mixing device, 24. Stabilizer inlet, 25. Bend pipe section, 26. Self-excited bubble head, 27. Application port, 28. Physical property monitoring module, 29. Optical monitoring module. DETAILED DESCRIPTION

[0042] The present invention will be further described below by way of examples.

[0043] like Figure 1 As shown, a concealed fire source prevention device includes a seamless steel pipe 1, liquid CO 2 Storage tank 14, foaming material storage tank 5 and stabilizer storage tank 4, liquid CO 2 The storage tank 14, the foaming material storage tank 5 and the stabilizer storage tank 4 are arranged outside the front end of the seamless steel pipe 1. The end of the seamless steel pipe 1 is provided with an effect application port 27. A self-exciting bubble head 26 is provided in the seamless steel pipe 1 near the effect application port 27. A curved pipe section 25 is provided at the end of the self-exciting bubble head 26 away from the effect application port 27.

[0044] The curved pipe section 25 passes liquid CO 2 The pipeline 15 and the liquid CO 2 The storage tank 14 is connected to the liquid CO in the seamless steel pipe 1. 2 A phase change control unit 16 and a static mixing device 23 are sequentially arranged on the delivery pipe 15 toward the effect application port 27. The static mixing device 23 is connected to the foaming material storage tank 5 through an injection pipe 9. An injection pump 10 is arranged on the injection pipe 9.

[0045] The injection pump 10 is a screw pump or a plunger pump, and the injection pipe 9 is made of high pressure resistant and corrosion resistant materials with an inner diameter of 30-120 mm;

[0046] The front end of the curved pipe section 25 is connected to the liquid CO 2 A stabilizer inlet 24 is provided at the connection of the delivery pipeline 15, and is connected to the stabilizer storage tank 4 through the injection pipeline 2. A micro-injection pump 3 is provided on the injection pipeline 2; the micro-injection pump 3 and the injection pipeline 2 uniformly add the stabilizer to the foaming system through the stabilizer inlet 24 in the form of a solution or a dispersion. The selection of the position of the stabilizer inlet 24 can ensure that the stabilizer can play a role in the first time after the problem is detected. Different response strategies are formulated according to the degree of instability. For example, for mild instability, the amount of stabilizer added can be appropriately increased; for moderate instability, in addition to increasing the amount of stabilizer added, the injection rate of the foaming material can also be slightly reduced; for severe instability, it may be necessary to suspend the injection of the foaming material, adjust the amount of stabilizer added and other related parameters, and continue the foaming process after the pore structure is stable; the micro-injection pump 3 has a precise flow control function, and can accurately inject the stabilizer solution or dispersion into the impact foaming system according to the preset addition amount and addition frequency; the micro-injection pump 3 and the foaming material injection pump 10 are designed as one body, and the injection pipeline 2 is suspended above the injection pipeline 9 and is detachable, with an inner diameter of 10-20mm;

[0047] Concealed fire source prevention and control devices also include:

[0048] Cell structure monitoring module, used to monitor the stability of cell structure during foaming process;

[0049] Fire area prevention and control effect monitoring module, used to monitor underground temperature and gas concentration information;

[0050] The ground monitoring center is used to receive feedback from the pore structure monitoring module and the fire area prevention and control effect monitoring module for centralized control or alarm.

[0051] Furthermore, the phase change control unit 16 includes a pressure regulating unit and a temperature regulating unit. The pressure regulating unit includes a pressure pump 17, a regulating valve 18 and a pressure sensor 19 arranged in sequence along the fluid conveying direction. The temperature regulating unit is arranged after the pressure regulating unit along the fluid conveying direction, and includes a heating device 20, a cooling device 22 and a phase change temperature sensor 21.

[0052] The temperature regulating unit is based on the heat exchange principle and regulates the CO at the end of the drilling hole through the heating device 20 or the cooling device 22. 2 The temperature and pressure regulating unit controls the CO through the pressure sensor 19, the regulating valve 18 and the pressure pump 17. 2 Pressure, CO 2 Phase change is stably achieved at the end of the borehole. The pressure pump 17 is a piston booster pump or a diaphragm booster pump with a boost ratio of 1.5-5 times. When the pressure is lower than the supercritical pressure of 7.38MPa, the booster device starts. The pressure sensor 19 is a high-precision piezoresistive type with an accuracy of ±0.01MPa, which can monitor the pressure value.

[0053] The heating device 20 can be an electric heating wire, which is evenly covered around the liquid CO 2 The temperature of the bottom wall and front wall of the heating tank of the delivery pipeline 15 is adjusted by controlling the power, or a hot oil circulation heating system is used to transfer heat through the hot oil flowing in the heat exchanger of the pipeline wall; the cooling device 22 can choose liquid nitrogen or cold water circulation system, and the liquid nitrogen vaporizes and absorbs heat or the cold water flows in the cooling coil to take away the heat, and evenly covers the top wall and rear wall of the heating tank. When CO is needed 2 When the temperature changes to the supercritical state, the heating device 20 is started to increase the temperature to more than 31.1°C. The power of the heating device 20 is based on the CO 2 The flow rate and phase change require precise adjustment between 1-10 kilowatts. The phase change temperature sensor 21 is installed after the heating device 20 or the cooling device 22, with an accuracy of ±0.1°C, and monitors the CO 2 The temperature is fed back to the control system to automatically adjust the operation of the heating or cooling device 22.

[0054] In order to achieve stable delivery control, further, liquid CO 2The storage tank 14 and the foaming material storage tank 5 are both equipped with a liquid level meter 13. 2 The storage tank 14 is also equipped with a pressure gauge 11 and a safety valve 12. A stirring device 8 is installed in the foaming material storage tank 5. A feeding port 6 with a sealing cover is provided at the top of the foaming material storage tank 5. 2 The storage tank 14 is made of a high-strength, high-pressure-resistant and low-temperature-resistant metal material, and can be cylindrical or spherical in shape. Its design complies with the pressure vessel standards, and its volume needs to be determined according to the scope and scale of the hidden fire source to be processed; liquid CO 2 The liquid level gauge 13 on the storage tank 14 adopts a high-precision ultrasonic liquid level gauge and a radar liquid level gauge; the opening pressure of the safety valve 12 is slightly higher than the normal working pressure to prevent the storage tank from overpressure explosion. The foam material storage tank 5 is made of corrosion-resistant material, and the volume needs to be determined according to the scope and scale of the hidden fire source to be treated; the stirring device 8 adopts a double-layer inclined blade turbine stirring blade, and the speed can be adjusted between 10-100 rpm to prevent the foam material from settling or stratifying; the liquid level gauge 13 on the foam material storage tank 5 adopts a glass tube liquid level gauge or a magnetic flap liquid level gauge.

[0055] Furthermore, liquid CO 2 The conveying pipeline 15 is a seamless steel pipe 1 made of low-temperature and high-pressure resistant high-quality carbon steel or alloy steel, with an inner diameter of 20-100 mm and a multi-layer composite structure, including an outer anti-corrosion and pressure-resistant protective layer coated with epoxy coal tar paint or polyethylene coating, an intermediate insulation layer of polyurethane foam or rock wool, and an inner layer of low-temperature and chemical corrosion resistant material layer of polytetrafluoroethylene or lined stainless steel. The pipelines are connected by a combination of flanges and sealing gaskets and fixed by brackets and hangers. The connecting part is provided with a telescopic margin, which is achieved by a metal bellows or a spring-type expansion joint, and the telescopic amount is 5-20 mm.

[0056] Furthermore, the static mixing device 23 is provided with twisted blades or spiral blades for achieving rapid and uniform mixing of multiple fluids.

[0057] Furthermore, the pore structure monitoring module obtains the pore structure information by at least one of physical property monitoring and optical monitoring.

[0058] The physical property monitoring module 28 inserts a viscosity sensor and a density sensor into the foaming material to measure the viscosity and density of the foaming material in real time. When the viscosity value changes abnormally or the density fluctuates abnormally, it is judged that the cell structure may be unstable.

[0059] The optical monitoring module 29 is provided with a light emitting and detecting device around the foaming container or pipe, emits light into the foaming material, and obtains the cell structure information by detecting parameters such as the intensity and angle of the scattered light. When an abnormal change in the light scattering parameters is detected, it indicates that the cell structure may be unstable.

[0060] A method for preventing and controlling hidden fire sources, based on the above-mentioned hidden fire source prevention and control device, comprises:

[0061] The drilling arrangement system is used to plan and construct drilling holes according to the underground geological conditions of the coal mine and the suspected hidden fire source area, so that the drilling holes can reach the target area;

[0062] CO 2 Transport and phase change control systems, including liquid CO 2 Storage tank 14, liquid CO 2 The delivery pipeline 15 and the phase change control unit 16 are used to transfer liquid CO 2 The phase change control unit 16 is delivered to the end of the drilling hole and controls its phase change to produce an impact effect;

[0063] The foaming material injection system includes a foaming material, a foaming material storage tank 5, an injection pump 10, an injection pipeline 9, a nucleating agent 7, a micro-injection pump 3 and an injection pipeline 2; it is used to inject the foaming material into the end of the borehole, and the foaming material and liquid CO 2 Supercritical CO formed by phase transition 2 After being mixed in the static mixing device 23, it enters the ambient coal body through the self-excited bubble head 26;

[0064] The monitoring and feedback system includes a pore structure monitoring module and a fire zone prevention and control effect monitoring module; the pore structure monitoring module is used to monitor the stability of the pore structure during the foaming process; the fire zone prevention and control effect monitoring module is used to monitor the underground temperature and gas concentration information; the liquid CO is controlled based on the monitoring data feedback. 2 Delivery rate, phase change conditions, foaming material, nucleating agent 7 and stabilizer injection amount;

[0065] The specific steps are as follows:

[0066] Drilling construction: Use underground drilling equipment to construct according to the designed drilling layout plan, monitor the drilling direction, depth and geological conditions in real time to ensure that the drilling reaches the vicinity of the target area accurately; the drilling layout plan is a drilling network planning based on the acquired address conditions; geological conditions include detection and identification of coal seam parameters (thickness, inclination, hardness), top and bottom plate lithology, and geological structure (faults, folds, etc.), combined with temperature monitoring and gas composition analysis to determine suspected hidden fire source areas; drilling network planning is to use modeling technology to draw the location, angle and depth of drilling holes to form a three-dimensional coverage network; for example, around the goaf, the holes are fan-shaped or chessboard-shaped. to ensure that it covers areas where hidden fire sources may exist; high-performance drilling equipment suitable for underground operations, such as tunnel drilling rigs for coal mines, should be used as drilling equipment; during the construction process, drilling parameters such as drilling pressure, rotation speed, and flushing fluid flow rate should be adjusted according to the properties of different rock formations; for rock formations with higher hardness, the drilling pressure should be appropriately increased, the rotation speed should be reduced, and suitable drill bits, including diamond drill bits and carbide drill bits, should be selected; the deviation of the borehole should be monitored in real time, and the data should be fed back through the inclinometer installed on the drill pipe. If the deviation exceeds the range, the drilling direction should be adjusted in time; at the same time, mud wall protection or casing wall protection methods should be used to prevent the collapse of the borehole. For deeper boreholes, segmented drilling and segmented wall protection measures should be adopted;

[0067] CO 2 Transport and phase change: liquid CO 2 Through liquid CO 2 The delivery pipeline 15 is delivered to the end of the borehole, and the phase change control unit 16 adjusts the pressure and temperature parameters to make the liquid CO 2 Phase transition occurs, resulting in supercritical CO with high diffusivity and solubility 2 , can quickly diffuse into the foaming material and penetrate into the cracks and pores of the coal body; phase change conditions: when the temperature is higher than 31.1℃ and the pressure is higher than 7.38MPa, it becomes a supercritical state, CO 2 A phase change occurs;

[0068] Mixed foaming: The foaming material and the nucleating agent 7 flow to the static mixing device 23 at the end of the borehole through the injection pipe 9 under the action of the injection pump 10, and mix with the supercritical CO regulated by the phase change control unit 16. 2 Mixing, CO during mixing 2 With its high diffusivity and solubility in the supercritical state, it can be quickly and evenly mixed with the foaming material to form the foaming material / supercritical CO 2 A homogeneous system, which continues to flow along the pipeline toward the effect application port 27 and the high-temperature and low-pressure coal body;

[0069] Foaming and prevention: Foaming materials / supercritical CO 2The homogeneous system will undergo phase change again or maintain a supercritical state due to changes in the temperature and pressure environment of the self-excited bubble head 26, the effect port 27 and the coal body itself. This is manifested as the partial thermodynamic stability being broken, causing the system to undergo phase separation, CO 2 The gas nucleus is precipitated and the nucleating agent 7 also starts to play a role, providing core sites. 2 The gas begins to diffuse into the gas core, causing the gas core to grow continuously, that is, part of the supercritical CO 2 Phase change impact foaming promotes the formation of pore structure. The foamed material directly reduces the temperature of the fire zone. The other part of the foaming material / supercritical CO that has not undergone phase change 2 The system directly enters the ambient coal, and the supercritical CO 2 Relying on its own molecular movement ability, it quickly penetrates into the cracks and pores of the coal body, and also drives the foaming material into these parts. Finally, the phase change impact increases the pores, driving the foaming material to fill the cracks and pores of the coal body, isolating the air and preventing coal oxidation to achieve the purpose of preventing and controlling hidden fire sources. The implementation effect is as follows Figure 2 As shown;

[0070] Monitoring and feedback: The phase change temperature sensor 21 and the pressure sensor 19 in the phase change control unit 16 monitor the liquid CO in the phase change control unit 16 in real time. 2 The temperature and pressure of the borehole are measured to make adjustments; the pore structure monitoring module is used to monitor the state of the pore structure formed during the foaming process in real time, so as to accurately control the addition of stabilizer through the micro-injection pump 3 to prevent the occurrence of phenomena such as bubble merging, rupture or collapse, ensure the smooth progress of the foaming process, and improve the effect of the foaming material on the prevention and control of hidden fire sources; the fire area prevention and control effect monitoring module is to set a borehole temperature sensor and a gas concentration sensor in the coal body around the end of the borehole. The borehole temperature sensor is a thermocouple or thermistor type with a measurement range of -20℃-1500℃ and an accuracy of ±0.5℃; the gas concentration sensor includes an infrared absorption type CO 2 Concentration sensors, laser oxygen concentration sensors and laser carbon monoxide concentration sensors have corresponding high-precision measurement capabilities, CO 2 The concentration accuracy is ±0.01%, the oxygen concentration accuracy is ±0.1%, and the carbon monoxide concentration accuracy is ±0.1ppm. It realizes real-time monitoring and feedback of the combustion and extinction of the fire area, real-time monitoring of the drilling environment temperature and the changes in various gas concentration parameters, reflecting the combustion and extinction status of hidden fire sources, and evaluating the prevention and control effects based on the monitoring data feedback. If necessary, alarm or adjust the liquid CO 2 Delivery rate, phase change conditions, foaming material, nucleating agent 7 and stabilizer injection amount.

[0071] Furthermore, the foaming material is one of a polyurethane foaming material containing an ammonium polyphosphate flame retardant, a phenolic foaming material composited with melamine pyrophosphate and pentaerythritol, and an expandable graphite composite melamine foaming material.

[0072] Polyurethane foam material containing ammonium polyphosphate flame retardant, wherein the ammonium polyphosphate decomposes when heated to produce phosphoric acid, ammonia and other substances, which promote the dehydration and carbonization of the polyurethane material to form a porous carbon foam layer, and the ammonia dilutes the oxygen concentration;

[0073] The phenolic foaming material is composed of melamine pyrophosphate and pentaerythritol. Under high temperature, melamine pyrophosphate decomposes to produce phosphoric acid and melamine and other substances. Phosphoric acid catalyzes the carbonization reaction of phenolic resin and promotes the formation of an expanded carbon layer together with pentaerythritol.

[0074] Expandable graphite is composited with melamine foaming material. At high temperature, expandable graphite expands rapidly to form a worm-like carbon structure, building a multi-layered heat insulation and oxygen isolation barrier inside the foaming material. Melamine releases nitrogen to further reduce oxygen concentration.

[0075] Furthermore, the nucleating agent 7 is pre-mixed with the foaming material or directly added and stirred evenly by the stirring device 8 .

[0076] The present invention arranges the system of drilling holes, CO 2 The four parts of the transportation and phase change control system, the foaming material injection system and the monitoring and feedback system realize the hidden fire source prevention technology integrating drilling-transportation-injection-monitoring.

Claims

1. A concealed fire source prevention device, characterized in that: It comprises a seamless steel pipe (1), a liquid CO2 storage tank (14), a foaming material storage tank (5) and a stabilizer storage tank (4); the liquid CO2 storage tank (14), the foaming material storage tank (5) and the stabilizer storage tank (4) are arranged outside the front end of the seamless steel pipe (1); an effect application port (27) is provided at the end of the seamless steel pipe (1); a self-exciting bubble head (26) is provided near the effect application port (27) in the seamless steel pipe (1); and a curved pipe section (25) is provided at the end of the self-exciting bubble head (26) away from the effect application port (27); The curved pipe section (25) is connected to the liquid CO2 storage tank (14) through the liquid CO2 delivery pipe (15). A phase change control unit (16) and a static mixing device (23) are sequentially provided on the liquid CO2 delivery pipe (15) located in the seamless steel pipe (1) toward the effect application port (27). The static mixing device (23) is connected to the foaming material storage tank (5) through the injection pipe (9). The injection pipe (9) is provided with an injection pump (10); A stabilizer inlet (24) is provided at the connection between the front end of the curved pipe section (25) and the liquid CO2 delivery pipe (15), and is connected to the stabilizer storage tank (4) through an injection pipe (2), and a micro-injection pump (3) is provided on the injection pipe (2); Concealed fire source prevention and control devices also include: Cell structure monitoring module, used to monitor the stability of cell structure during foaming; Fire area prevention and control effect monitoring module, used to monitor underground temperature and gas concentration information; The ground monitoring center is used to receive feedback from the pore structure monitoring module and the fire area prevention and control effect monitoring module for centralized control or alarm.

2. A concealed fire source prevention device according to claim 1, characterized in that: The phase change control unit (16) comprises a pressure regulating unit and a temperature regulating unit. The pressure regulating unit comprises a pressure pump (17), a regulating valve (18) and a pressure sensor (19) which are arranged in sequence along the fluid conveying direction. The temperature regulating unit is arranged after the pressure regulating unit along the fluid conveying direction and comprises a heating device (20), a cooling device (22) and a phase change temperature sensor (21).

3. A concealed fire source prevention device according to claim 1, characterized in that: A liquid level meter (13) is installed on both the liquid CO2 storage tank (14) and the foaming material storage tank (5). A pressure gauge (11) and a safety valve (12) are also installed on the liquid CO2 storage tank (14). A stirring device (8) is installed in the foaming material storage tank (5). A feeding port (6) with a sealing cover is provided at the top of the foaming material storage tank (5).

4. A concealed fire source prevention device according to claim 1, characterized in that: The liquid CO2 transmission pipeline (15) adopts a multi-layer composite structure, including an outer anti-corrosion and pressure-resistant protective layer, an intermediate thermal insulation layer and an inner low-temperature and chemical corrosion resistant material layer. The pipelines are connected by a combination of flanges and sealing gaskets and fixed by brackets and hangers. The connection parts are provided with expansion margins.

5. A concealed fire source prevention device according to claim 1, characterized in that: The static mixing device (23) is provided with twisted blades or spiral blades for achieving rapid and uniform mixing of multiple fluids.

6. A concealed fire source prevention device according to claim 1, characterized in that: The cell structure monitoring module obtains cell structure information by at least one of physical property monitoring and optical monitoring.

7. A method for preventing and controlling hidden fire sources, based on the hidden fire source prevention and control device according to any one of claims 1 to 6, characterized in that: include: The drilling arrangement system is used to plan and construct drilling holes according to the underground geological conditions of the coal mine and the suspected hidden fire source area, so that the drilling holes can reach the target area; A CO2 transport and phase change control system, comprising a liquid CO2 storage tank (14), a liquid CO2 transport pipeline (15) and a phase change control unit (16); the phase change control unit (16) is used to transport the liquid CO2 to the end of the borehole and control its phase change to produce an impact effect; A foaming material injection system comprises a foaming material, a foaming material storage tank (5), an injection pump (10), an injection pipeline (9), a nucleating agent (7), a micro-injection pump (3) and an injection pipeline (2); the foaming material is used to inject the foaming material into the end of the borehole; the foaming material is mixed with supercritical CO2 formed by phase change of liquid CO2 in a static mixing device (23) and then enters the ambient coal body through a self-excited bubble head (26); The monitoring and feedback system includes a pore structure monitoring module and a fire zone prevention and control effect monitoring module; the pore structure monitoring module is used to monitor the stability of the pore structure during the foaming process; the fire zone prevention and control effect monitoring module is used to monitor the underground temperature and gas concentration information; according to the monitoring data feedback, the liquid CO2 delivery amount, phase change conditions, foaming materials, nucleating agent (7) and stabilizer injection amount are controlled; The specific steps are as follows: Drilling construction: Use downhole drilling equipment to construct according to the designed drilling arrangement plan, monitor the drilling direction, depth and geological conditions in real time to ensure that the drilling reaches the target area accurately; CO2 transportation and phase change: liquid CO2 is transported to the end of the borehole through a liquid CO2 transportation pipeline (15), and a phase change control unit (16) adjusts pressure and temperature parameters to cause the liquid CO2 to undergo a phase change to obtain supercritical CO2; Mixing and foaming: The foaming material and the nucleating agent (7) flow through the injection pipe (9) to the static mixing device (23) at the end of the borehole under the action of the injection pump (10), and are mixed with the supercritical CO2 regulated by the phase change control unit (16) to form a foaming material / supercritical CO2 homogeneous system. The homogeneous system continues to flow along the pipe to the effect port (27) and the high-temperature and low-pressure coal body; Foaming and prevention: The foaming material / supercritical CO2 homogeneous system will undergo phase change again or maintain a supercritical state due to changes in the self-excited bubble head (26), the effect port (27) and the temperature and pressure environment of the coal body itself, that is, part of the supercritical CO2 phase change impact foaming promotes the formation of a pore structure, and the foamed material directly reduces the temperature of the fire zone. The other part of the foaming material / supercritical CO2 system that has not undergone phase change directly enters the ambient coal body. The supercritical CO2 quickly penetrates into the cracks and pores of the coal body by virtue of its own molecular movement ability, and also drives the foaming material to enter these parts. Finally, the phase change impact increases the pores, driving the foaming material to fill the cracks and pores of the coal body, isolating the air and preventing coal oxidation to achieve the purpose of preventing and controlling hidden fire sources; Monitoring and feedback: The temperature and pressure of the liquid CO2 in the phase change control unit (16) are monitored in real time by the phase change temperature sensor (21) and the pressure sensor (19) in the phase change control unit (16) so as to make adjustments; The pore structure monitoring module is used to monitor the state of the pore structure formed during the foaming process in real time, so as to accurately control the addition of the stabilizer through the micro-injection pump (3); the fire area prevention and control effect monitoring module is to set a borehole temperature sensor and a gas concentration sensor in the coal body around the end of the borehole, to monitor the changes in the borehole environment temperature and various gas concentration parameters in real time, to reflect the combustion and extinction status of the hidden fire source, to evaluate the prevention and control effect based on the monitoring data feedback, and to alarm or adjust the liquid CO2 delivery rate, phase change conditions, foaming materials, nucleating agent (7) and stabilizer injection amount when necessary.

8. A method for preventing and controlling hidden fire sources according to claim 7, characterized in that: The foaming material is one of a polyurethane foaming material containing an ammonium polyphosphate flame retardant, a phenolic foaming material compounded by melamine pyrophosphate and pentaerythritol, and an expandable graphite composite melamine foaming material.

9. A method for preventing and controlling hidden fire sources according to claim 7, characterized in that: The nucleating agent (7) is pre-mixed with the foaming material or directly added and stirred uniformly by a stirring device (8).

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