Multiphase foam flame-retardant fire extinguishing method and system for fire area of coal field

Abstract

The invention relates to the technical field of coal mine safety and fire prevention and extinguishment, and discloses a coal field fire area multiphase foam flame-retardant fire extinguishing method and system.The coal field fire area multiphase foam flame-retardant fire extinguishing method comprises the following steps that S1, multiphase foam is prepared, the multiphase foam comprises a gas phase, a liquid phase and a solid phase, the gas phase is mixed gas of nitrogen and carbon dioxide, and the liquid phase is mixed gas of nitrogen and carbon dioxide; the liquid phase takes a bio-based surfactant as a base material and is compounded with a temperature response type epoxy resin emulsion, and the solid phase is composite flame-retardant particles; s2, the coal field fire area is investigated, an unmanned aerial vehicle carrying an infrared thermal imaging sensor and a gas sensor is used for scanning temperature distribution and crack positions of the fire area, and a three-dimensional thermodynamic diagram of the fire area is generated; and S3, obtaining the three-dimensional thermodynamic diagram of the fire area. By means of an intelligent investigation and conveying system, precise adaptation of a complex coal field fire area and efficient utilization of fire extinguishing resources are achieved, and the defects that in the prior art, under the heterogeneous geological condition, the number of coverage blind areas is large, and resource waste is large are overcome.

Description

Technical Field

[0001] This invention relates to the field of coal mine safety and fire prevention and extinguishing technology, specifically to a multiphase foam flame-retardant fire extinguishing method and system for coalfield fire zones. Background Technology

[0002] Coalfield fire zones are areas of continuous combustion caused by spontaneous combustion of coal or external ignition sources during coal mining and storage. These zones not only waste significant amounts of coal resources but also release toxic and harmful gases such as carbon monoxide and sulfur dioxide, polluting the atmosphere. Furthermore, the high temperatures can cause coal seam roof collapses and trigger gas explosions, posing a serious threat to the surrounding ecological environment and human safety. Therefore, developing efficient, long-lasting fire extinguishing technologies adapted to complex coalfield geology is a crucial issue that urgently needs to be addressed in the field of safe production and ecological protection in the coal industry. Currently, the industry's fire extinguishing technologies for coalfield fire zones are mainly divided into three categories. Each type of technology has formed specific application scenarios based on different working principles, but all of them have insurmountable technical limitations: The first type is the water injection extinguishing method. Its core principle is to inject a large amount of clean water into the fire zone through fixed pipelines or boreholes. Water's high specific heat capacity and heat absorption during vaporization lower the coal temperature. Simultaneously, the water forms a film on the coal surface to isolate oxygen, thereby inhibiting the combustion reaction. This technology is widely used in shallow coalfield fire zones (fire depth less than 5 meters) where the fire is weak and coal seam fissures are not well-developed, due to its simple equipment requirements, convenient operation, and low raw material costs. However, coalfield geology is generally heterogeneous, with numerous fissures of varying sizes between coal seams and rock strata. Injected water can easily seep rapidly along these fissures to the outside of the fire zone, making it difficult to effectively retain it in the high-temperature core area, resulting in numerous blind spots for fire suppression. Furthermore, when high-temperature coal comes into contact with water, it rapidly vaporizes, producing a large amount of water vapor. This high-pressure water vapor may not only exacerbate the expansion of coal fissures but may also react chemically with the coal to generate flammable gases such as hydrogen and carbon monoxide, increasing the safety risk of gas explosions. In addition, incompletely vaporized water mixes with coal dust to form coal slurry, which can easily clog boreholes and pipelines used for subsequent fire suppression operations, making it difficult to carry out secondary fire suppression operations. The second type is the inert gas extinguishing method. This technology continuously injects inert gases such as nitrogen and carbon dioxide into the fire zone through nitrogen generation equipment or carbon dioxide storage devices. The chemical inertness of these gases dilutes the oxygen concentration in the fire zone's air. When the oxygen concentration drops below 12%, the coal combustion reaction stops due to the lack of oxidizer. Compared to water injection extinguishing methods, inert gases have stronger diffusion properties and can penetrate into narrow fissures. Therefore, they show certain advantages in fire zones with good sealing (such as underground coal seam roadways) and relatively uniform fissure distribution. However, the low density of inert gas makes it easy to escape through cracks at the top of the fire zone. In order to maintain the oxygen concentration threshold for effective fire extinguishing, a large amount of inert gas needs to be continuously injected, resulting in high energy consumption of equipment and high cost of gas raw materials. For open fire zones (such as spontaneous combustion zones in open-pit coal mines) or fire zones with large faults, the inert gas escapes even faster, making it difficult to form a stable flame-retardant atmosphere. More importantly, inert gas can only achieve "immediate flame suppression". Once the injection stops, external air will re-enter the fire zone through cracks, and the coal temperature will rise again, making it very easy to reignite, and thus unable to achieve long-term fire control. The third type is the ordinary foam fire extinguisher. Its principle involves mixing a surfactant solution with air or an inert gas through a foam generator to form a gas-liquid two-phase foam. The foam, with its large specific surface area, covers the coal surface, cooling it by absorbing heat through water vaporization and isolating oxygen through the foam film. Simultaneously, the foam's adhesiveness reduces the loss of the extinguishing agent. This technology overcomes the seepage problem of water injection fire extinguishing and the diffusion problem of inert gas fire extinguishing, and is frequently used in shallow to medium-depth (5-15 meters deep) coalfield fires with moderate intensity. However, ordinary foam has poor stability. When exposed to the high temperature of the fire zone, the moisture in the foam film evaporates rapidly. The half-life of foam is usually only 12 to 24 hours. After it breaks, it can no longer play a flame-retardant role, resulting in a significant risk of reignition in the fire zone. Moreover, most existing ordinary foams are designed with a single formula, with fixed types and concentrations of surfactants, which cannot adapt to the wide temperature fluctuations of 200-800℃ in coalfield fire zones. In addition, some ordinary foams contain fluorides and sulfonate surfactants, which can seep into the soil and groundwater with rainwater after fire extinguishing, causing heavy metal and organic pollutant residues and causing secondary ecological pollution. In summary, while existing coalfield fire extinguishing technologies possess some fire-extinguishing capabilities in specific scenarios, they all suffer from core technological bottlenecks: First, they have poor adaptability to complex geological conditions, failing to achieve precise coverage in fractured and heterogeneous coalfield geology, easily creating fire extinguishing blind spots; second, their flame-retardant effect is short-lived, lacking a long-term flame-locking mechanism, resulting in a high rate of reignition after fire extinguishing; third, resource utilization efficiency is low, with fixed pipe deployment and manual monitoring leading to significant waste of extinguishing media and energy; and fourth, environmental and safety hazards are prominent, with some technologies posing risks of environmental pollution or explosion. Therefore, those skilled in the art propose a multiphase foam flame-retardant fire extinguishing method and system for coalfield fire zones to address these issues. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a multiphase foam flame-retardant extinguishing method and system for coalfield fire zones, which solves the problems of poor adaptability to complex geological conditions, short flame-retardant effect and easy reignition, as well as low resource utilization efficiency in existing coalfield fire zone extinguishing technologies.

[0004] To achieve the above objectives, the present invention provides a multiphase foam flame-retardant extinguishing method for coalfield fire zones, comprising the following steps: S1. Prepare a multiphase foam, wherein the multiphase foam comprises a gas phase, a liquid phase and a solid phase, wherein the gas phase is a mixture of nitrogen and carbon dioxide, the liquid phase is based on a bio-based surfactant and compounded with a temperature-responsive epoxy resin emulsion, and the solid phase is composite flame-retardant particles. S2. Conduct reconnaissance of coalfield fire areas by using drones equipped with infrared thermal imaging sensors and gas sensors to scan the temperature distribution and crack locations of the fire areas and generate a three-dimensional thermal map of the fire areas. S3. Based on the three-dimensional thermal map of the fire zone, flexible foam delivery pipelines are dynamically laid out in the high-temperature core area and fissure channels of the fire zone by a tracked intelligent robot. S4. The multiphase foam prepared in step S1 is injected into the fire zone through the flexible foam delivery pipeline. When the multiphase foam comes into contact with the preset temperature in the fire zone, the temperature-responsive epoxy resin emulsion in the liquid phase is triggered to cure, fixing the solid-phase composite flame-retardant particles to the surface of the coal body and the cracks. S5. The sensor built into the flexible foam delivery pipeline collects the fire zone status data in real time. Based on the status data, it is determined whether the fire zone needs to be replenished with multiphase foam. If replenishment is required, multiphase foam is replenished to the target area by a tracked intelligent robot.

[0005] Through the aforementioned technical solution, and by following a series of steps—"preparing adaptable multiphase foam, accurately detecting fire zones, dynamically deploying delivery pipelines, efficiently injecting flame-retardant foam, and real-time monitoring and feedback for replenishment"—the synergistic effect of the gas, liquid, and solid phases in the multiphase foam can be utilized to solidify the solid particles onto the coal surface and within fissures through liquid phase solidification when the fire zone comes into contact with a preset temperature. This achieves physical oxygen and heat insulation as well as chemical flame retardancy for the fire zone. Simultaneously, relying on the cooperation of drones and tracked intelligent robots, the high-temperature core and fissures of the fire zone are accurately located, and pipelines are dynamically deployed. Combined with built-in sensors, the fire zone status is monitored in real time, and foam is replenished in a timely manner. This effectively adapts to the complex terrain and fissure distribution of coalfield fire zones, efficiently extinguishing existing fire points and preventing fire reignition, significantly improving the accuracy, stability, and long-term effectiveness of flame-retardant fire suppression in coalfield fire zones.

[0006] Preferably, in step S1, the volume ratio of nitrogen to carbon dioxide in the gas phase is 7:3, the bio-based surfactant is tea saponin, and the critical curing temperature of the temperature-responsive epoxy resin emulsion is 80-120℃.

[0007] Through the above technical solution, nitrogen and carbon dioxide are mixed in a specific ratio in the gas phase. The inertness of nitrogen can achieve stable oxygen isolation, while carbon dioxide can enhance the flame retardant effect. The two work together to optimize the flame retardant and oxygen isolation performance of the gas phase. Tea saponin is selected as a bio-based surfactant, which not only has excellent emulsification and foaming capabilities, helping to form a stable and uniformly dispersed multiphase foam system, but also meets environmental protection requirements and meets the needs of green fire extinguishing. The critical curing temperature of the temperature-responsive epoxy resin emulsion is set to the typical temperature range of the coalfield fire zone, which can ensure that after the multiphase foam is injected into the fire zone, the emulsion will be promptly triggered to cure at the target temperature, thereby firmly fixing the solid-phase composite flame retardant particles to the coal surface and cracks, effectively ensuring the stability and reliability of the flame retardant fire extinguishing effect.

[0008] Preferably, in step S1, the composite flame-retardant particles are composed of nano-magnesium hydroxide and expandable graphite, wherein the nano-magnesium hydroxide has a particle size of 50-100 nm.

[0009] The above technical solution uses composite flame-retardant particles composed of nano-magnesium hydroxide and expandable graphite as the solid phase component. Nano-magnesium hydroxide, with its nano-sized particle size, has a larger specific surface area and stronger dispersibility, allowing it to fully integrate with other components in the foam system, enhancing the coverage and flame-retardant effect on the fire zone. Expandable graphite expands when heated, forming a dense expanded carbon layer that effectively blocks heat transfer and oxygen contact. The synergistic effect of the two not only leverages the high-efficiency flame-retardant properties of nano-magnesium hydroxide but also utilizes the expansion barrier properties of expandable graphite to further enhance the flame-retardant and fire-extinguishing capabilities of multiphase foam in coalfield fire zones. Furthermore, it better adapts to the subsequent liquid-phase solidification process, being firmly fixed to the coal surface and fissures, achieving long-term flame retardancy and reducing the risk of reignition in the fire zone.

[0010] Preferably, in step S1, the specific process for preparing multiphase foam is as follows: first, the liquid phase and the solid phase composite flame retardant particles are placed in an emulsification device for ultrasonic dispersion, then the gas phase is introduced into the dispersed mixture, and finally, the mixture is processed by a high-shear emulsifier to form multiphase foam.

[0011] Through the above technical solution, in the process of preparing multiphase foam, the liquid and solid composite flame-retardant particles are first placed in an emulsification device for ultrasonic dispersion. The ultrasonic action can make the solid particles more uniformly dispersed in the liquid phase, avoiding particle agglomeration and laying the foundation for the subsequent formation of stable multiphase foam. Then, the gas phase is introduced into the dispersed mixture to fully integrate the gas phase into the liquid-solid mixture system and increase the gas content of the foam. Finally, the high-shear emulsifier further enhances the mixing effect between the phases, promotes the tight combination of the gas, liquid and solid phases, and ultimately forms a multiphase foam with uniform dispersion, strong stability and good synergistic effect of each component. This ensures that it can fully exert its flame-retardant and fire-extinguishing effect in coalfield fire areas and better adhere to the coal surface and fill the cracks.

[0012] Preferably, in step S2, when the UAV scans the fire zone, it simultaneously collects oxygen concentration data of the fire zone, and the three-dimensional thermal map of the fire zone includes the fire zone temperature value, crack size and oxygen concentration distribution information.

[0013] By simultaneously collecting oxygen concentration data in the fire zone and integrating fire zone temperature, fissure size, and oxygen concentration distribution information into a three-dimensional thermal map of the fire zone, staff can gain a more comprehensive and accurate understanding of the actual combustion state of the fire zone. This not only clarifies the specific conditions of the high-temperature core area and fissures but also allows for the assessment of the fire's activity level and potential spread trend through oxygen concentration distribution. This provides a more scientific and comprehensive basis for the subsequent dynamic deployment of foam delivery pipelines by tracked intelligent robots and the precise injection of multiphase foam into the high-temperature core area and fissure channels of the fire zone, thereby helping to improve the targeting and effectiveness of flame-retardant fire suppression in coalfield fire zones.

[0014] Preferably, in step S3, the tracked intelligent robot has terrain adaptation and autonomous obstacle avoidance functions, and when laying flexible foam delivery pipelines, the pipeline laying spacing is adjusted according to the size of the cracks in the fire zone.

[0015] Through the above technical solutions, the tracked intelligent robot can smoothly adapt to the complex and ever-changing terrain environment of the fire zone thanks to its terrain adaptation function. Its autonomous obstacle avoidance function can effectively avoid obstacles in the fire zone, ensuring the stability and safety of the pipeline laying process. At the same time, the robot adjusts the pipeline laying spacing according to the size of the fire zone cracks, which allows the flexible foam delivery pipeline to more accurately cover the crack area of ​​the fire zone, avoiding blind spots in foam delivery due to improper pipeline laying. This ensures that subsequent multiphase foam can be efficiently and accurately delivered to key locations in the fire zone, providing reliable pipeline support for improving the overall flame-retardant fire extinguishing effect.

[0016] Preferably, in step S4, a high-pressure injection method is used when injecting multiphase foam into the fire zone, and the injection pressure is dynamically adjusted by a booster device according to the depth of the cracks in the fire zone.

[0017] Through the above technical solutions, when injecting multiphase foam into the fire zone, the high-pressure injection method can provide sufficient driving force for the foam, making it easier to penetrate the complex structure of the fire zone. At the same time, by using a pressurization device to dynamically adjust the injection pressure according to the depth of the fissures in the fire zone, it can be ensured that the foam can fully fill fissures of different depths, avoiding the failure to effectively cover deep fissures due to insufficient pressure, and also preventing excessive pressure from causing unnecessary damage to the coal structure. Thus, the multiphase foam can act accurately and comprehensively on the key areas of the fire zone, giving full play to its flame-retardant and fire-extinguishing effects, and improving the effectiveness and rationality of fire-fighting operations.

[0018] Preferably, in step S5, the sensors built into the flexible foam delivery pipeline are a temperature sensor and an oxygen concentration sensor. When the sensors detect that the local temperature in the fire zone is higher than a preset threshold, the operation of replenishing multiphase foam is triggered.

[0019] Through the above technical solution, the temperature sensor and oxygen concentration sensor built into the flexible foam delivery pipeline can monitor the local temperature and oxygen concentration in the fire zone in real time, realizing dynamic control of the fire zone status. When the temperature sensor detects that the local temperature in the fire zone exceeds the preset threshold, it promptly triggers the multiphase foam replenishment operation, which can specifically replenish the fire in areas where the local temperature rises abnormally, avoiding the risk of reignition due to excessive temperature in these areas. At the same time, combined with oxygen concentration monitoring data, it can more comprehensively grasp the combustion status of the fire zone, further ensuring the continuity and stability of the multiphase foam flame retardant fire extinguishing effect and improving the reliability of fire zone management.

[0020] A multiphase foam flame-retardant fire extinguishing system for coalfield fire zones includes an intelligent detection module, a multiphase foam preparation module, a precision delivery module, and a real-time monitoring and feedback module; The intelligent reconnaissance module includes a drone equipped with an infrared thermal imaging sensor and a gas sensor, as well as a tracked intelligent robot with terrain adaptation and autonomous obstacle avoidance capabilities. The intelligent reconnaissance module is used to generate a three-dimensional heat map of the fire zone. The multiphase foam preparation module includes a mixed gas phase generator, a liquid phase emulsification tank, a solid phase dispersion tank, and a high-shear emulsifier. The mixed gas phase generator is used to prepare a mixed gas of nitrogen and carbon dioxide. The liquid phase emulsification tank is used to mix bio-based surfactants and temperature-responsive epoxy resin emulsions. The solid phase dispersion tank is used to store composite flame-retardant particles. The high-shear emulsifier is used to mix the gas phase, liquid phase, and solid phase to form multiphase foam. The precision delivery module includes a flexible foam delivery pipeline, a tracked pipe laying robot, and a foam booster pump. The tracked pipe laying robot is used to lay the flexible foam delivery pipeline, and the foam booster pump is used to adjust the injection pressure of the multiphase foam. The real-time monitoring and feedback module includes a temperature sensor, an oxygen concentration sensor, a data transmission terminal, and a central control platform. The temperature sensor and the oxygen concentration sensor are built into the flexible foam delivery pipeline. The data transmission terminal is used to transmit the data collected by the sensor. The central control platform is used to determine whether to trigger a refill operation based on the data.

[0021] Through the above technical solution, a three-dimensional thermal map of the fire zone is generated by a drone equipped with relevant sensors in the intelligent reconnaissance module and a tracked intelligent robot with adaptation and obstacle avoidance functions, accurately grasping the actual situation of the fire zone; the various devices in the multiphase foam preparation module are reasonably matched to prepare multiphase foam with suitable performance; the tracked pipe laying robot in the precision delivery module lays the pipeline and the foam booster pump adjusts the pressure to achieve precise delivery of multiphase foam; relying on the sensors, data transmission terminal and central control platform built into the real-time monitoring and feedback module, the fire zone status is dynamically monitored and timely replenishment operations are triggered. The four modules work together to form a complete fire extinguishing process from fire zone reconnaissance, foam preparation, precise delivery to dynamic monitoring and feedback, which greatly improves the accuracy, efficiency and sustainability of flame-retardant fire extinguishing in coalfield fire zones, and ensures the scientific rationality and safety of fire extinguishing operations.

[0022] This invention provides a multiphase foam flame-retardant fire extinguishing method and system for coalfield fire zones. It has the following beneficial effects: 1. This invention effectively solves the core pain points of existing coalfield fire extinguishing technologies—namely, "incomplete fire extinguishing and easy reignition"—through the three-phase synergistic design of multiphase foam and its temperature-responsive curing mechanism. The gas phase in the multiphase foam rapidly dilutes the oxygen concentration in the fire zone, achieving initial flame retardancy. The temperature-responsive epoxy resin emulsion in the liquid phase is triggered to cure upon contact with a preset temperature in the fire zone, firmly fixing the solid-phase composite flame-retardant particles to the coal surface and cracks, forming a permanent flame-retardant layer with both heat insulation and oxygen barrier functions, avoiding the problem of flame-retardant failure after traditional foam rupture. Simultaneously, sensors built into the flexible foam delivery pipeline collect real-time fire zone status data, and combined with the dynamic replenishment operation of a tracked intelligent robot, multiphase foam can be promptly replenished to areas with rising local temperatures, forming a complete fire control chain of "immediate fire extinguishing – curing and flame locking – dynamic replenishment and prevention."

[0023] 2. This invention relies on an intelligent reconnaissance and delivery system to achieve precise adaptation to complex coalfield fire zones and efficient utilization of firefighting resources, overcoming the shortcomings of existing technologies that suffer from "numerous blind spots and significant resource waste" under heterogeneous geological conditions. A drone equipped with infrared thermal imaging and gas sensors can accurately capture the temperature distribution, fissure locations, and oxygen concentration in the fire zone, generating a three-dimensional thermal map that provides precise data support for subsequent operations. Based on this thermal map, a tracked intelligent robot can dynamically deploy flexible foam delivery pipelines in key locations such as high-temperature core areas and fissure channels. It can also adjust the pipeline spacing according to the fissure size, avoiding the blindness of traditional fixed pipeline deployment. Attached Figure Description

[0024] Figure 1 This is the overall flowchart of the present invention; Figure 2 This is a flowchart of the multiphase foam preparation process of the present invention; Figure 3 This is a flowchart of the module interaction process of the present invention. Detailed Implementation

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Please see the appendix Figure 1 - Appendix Figure 3 This invention provides a method for extinguishing coalfield fires using multiphase foam flame retardant, comprising the following steps: S1. Prepare multiphase foam, which includes a gas phase, a liquid phase and a solid phase. The gas phase is a mixture of nitrogen and carbon dioxide. The liquid phase is based on a bio-based surfactant and compounded with a temperature-responsive epoxy resin emulsion. The solid phase is composite flame-retardant particles. The volume ratio of nitrogen to carbon dioxide in the gas phase is 7:3. The bio-based surfactant is tea saponin, and the critical curing temperature of the temperature-responsive epoxy resin emulsion is 120℃. The composite flame-retardant particles are composed of nano-magnesium hydroxide and expandable graphite, with the nano-magnesium hydroxide having a particle size of 100nm.

[0027] Specifically, nitrogen enhances the inert atmosphere of the foam system through its chemical stability, while carbon dioxide helps improve the explosion suppression effect in the fire zone and can synergize with the subsequent liquid-phase solidification reaction. The ratio of the two avoids the defect of easy escape of nitrogen alone and overcomes the problem of insufficient foam buoyancy due to the excessive density of carbon dioxide alone. The liquid phase uses tea saponin as a bio-based surfactant base material. This component is derived from natural plant extracts and can replace the fluoride and sulfonate chemical surfactants in existing ordinary foams, avoiding the risk of soil and groundwater pollution after fire extinguishing from the source. At the same time, a temperature-responsive epoxy resin emulsion with a critical curing temperature of 120°C is compounded in the liquid phase. This critical temperature value is precisely adapted to the shallow layers of coalfield fire zones. The common temperature range (200-800℃) ensures that the foam can quickly respond to temperature-triggered curing after being injected into the fire zone, rather than curing prematurely during normal temperature transportation. The solid phase uses composite flame-retardant particles composed of nano-magnesium hydroxide and expandable graphite. The particle size of the nano-magnesium hydroxide is set at 100nm. This particle size can ensure its uniform dispersion in the liquid phase, avoid particle agglomeration and foam rupture, and enhance the endothermic decomposition efficiency at high temperature by increasing the specific surface area. The expandable graphite can rapidly expand to form a dense carbon layer after being heated. The synergistic effect of the two can build a physical-chemical dual flame-retardant barrier on the surface of the coal body and in the cracks, making up for the shortcomings of existing foams that only rely on temporary coverage by gas-liquid two phases.

[0028] The specific process for preparing multiphase foam is as follows: first, the liquid and solid phase composite flame retardant particles are placed in an emulsification device for ultrasonic dispersion, then the gas phase is introduced into the dispersed mixture, and finally, the mixture is processed by a high-shear emulsifier to form multiphase foam.

[0029] Specifically, the gas phase is sheared into micron-sized microbubbles, while the liquid phase fully encapsulates the bubbles to form a stable liquid film. Solid-phase composite flame-retardant particles are uniformly attached to the surface of the liquid film or dispersed inside the liquid film, ultimately forming a three-phase tightly coordinated, highly stable multiphase foam. This ensures that the foam has the structural strength and uniform distribution of flame-retardant components required for subsequent fire zone injection.

[0030] S2. Conduct reconnaissance of coalfield fire areas. Use drones equipped with infrared thermal imaging sensors and gas sensors to scan the temperature distribution and crack locations of the fire areas and generate a three-dimensional thermal map of the fire areas. While the drones are scanning the fire areas, they simultaneously collect oxygen concentration data of the fire areas. The three-dimensional thermal map of the fire areas includes fire area temperature values, crack sizes, and oxygen concentration distribution information. Specifically, infrared thermal imaging sensors can generate thermal radiation images by utilizing temperature differences in different areas of a coalfield fire zone, accurately capturing the distribution range of the high-temperature core area of ​​the fire zone, temperature gradients, and the location contours of coal seam fissures. Meanwhile, gas sensors simultaneously collect oxygen concentration data at different points in the fire zone in real time to determine the degree of combustion activity and potential reignition risk areas. After data acquisition, data fusion technology is used to integrate the fire zone temperature values ​​and fissure size information obtained from infrared thermal imaging with the oxygen concentration distribution information collected by the gas sensors to construct a three-dimensional thermal map of the fire zone. This three-dimensional thermal map is not just a simple temperature visualization chart, but a comprehensive data carrier that can intuitively reflect the relationship between "temperature, spatial structure, and gas environment" in the fire zone. It can provide precise location guidance for the subsequent dynamic deployment of flexible foam delivery pipelines by tracked intelligent robots, and also provide data basis for adjusting the injection volume and injection pressure of multiphase foam. This effectively solves the problems of low efficiency of manual reconnaissance and blind firefighting operations caused by data fragmentation in existing technologies.

[0031] S3. Based on the three-dimensional thermal map of the fire zone, a tracked intelligent robot dynamically lays out flexible foam delivery pipelines in the high-temperature core area and fissure channels of the fire zone. The tracked intelligent robot has terrain adaptation and autonomous obstacle avoidance functions. When laying out flexible foam delivery pipelines, the pipeline laying spacing is adjusted according to the fissure size of the fire zone. Specifically, tracked intelligent robots, with their terrain adaptability, can flexibly adapt to complex terrains common in coalfield fire areas, such as uneven ground and shallow subsidence areas, avoiding pipeline interruptions due to terrain obstacles. Their autonomous obstacle avoidance function can identify obstacles in the fire area (such as exposed coal seams and collapsed rocks) in real time and plan detour paths, ensuring the safety and continuity of the pipeline laying process. When laying flexible foam pipelines, the robot will also dynamically adjust the pipeline laying spacing according to the fracture size marked on the three-dimensional thermal map of the fire area. For example, for large fracture channels (such as fractures with a width of more than 50cm), the pipeline laying spacing will be reduced to ensure that multiphase foam can fully fill the fracture interior. For small fractures (such as fractures with a width of less than 10cm), the pipeline laying spacing will be appropriately increased to avoid wasting pipeline resources, ultimately achieving a precise match between pipeline laying and the actual geological characteristics of the fire area.

[0032] S4. The multiphase foam prepared in step S1 is injected into the fire zone through a flexible foam delivery pipeline. When the multiphase foam comes into contact with the preset temperature in the fire zone, the temperature-responsive epoxy resin emulsion in the liquid phase is triggered to cure, fixing the solid-phase composite flame-retardant particles to the surface of the coal body and the cracks. When injecting the multiphase foam into the fire zone, a high-pressure injection method is adopted, and the injection pressure is dynamically adjusted according to the crack depth in the fire zone by a booster device.

[0033] Specifically, the multiphase foam prepared in step S1 is transported to the coalfield fire zone and injected through a flexible foam delivery pipeline. This flexible pipeline can flexibly adapt to the uneven terrain and complex fracture orientation of the fire zone, ensuring that the multiphase foam can accurately reach the high-temperature core area of ​​the fire zone and the interior of various fractures. The injection of multiphase foam adopts a high-pressure injection method. With the help of a pressurization device, the injection pressure is dynamically adjusted according to the actual depth of the fractures at different locations in the fire zone. For deeper fractures, the injection pressure is appropriately increased to promote the foam to fully penetrate into the depth of the fractures, while for shallower fractures, the injection pressure is appropriately reduced. The injection pressure avoids high-pressure impact that could cause further expansion of the cracks. When the multiphase foam injected into the fire zone comes into contact with the preset temperature of the fire zone, the temperature-responsive epoxy resin emulsion contained in the liquid phase will quickly trigger a curing reaction, changing from a liquid state to a solid structure. This solid structure can not only tightly adhere to the coal surface, but also fill the gaps in the coal cracks. At the same time, it can firmly fix the solid-phase composite flame-retardant particles on the coal surface and inside the cracks, forming a flame-retardant structure that can continuously play the role of oxygen isolation and heat insulation, avoiding the problem of traditional foam losing its flame-retardant effect due to the loss of solid particles caused by rupture.

[0034] S5. The flexible foam delivery pipeline uses built-in sensors to collect real-time fire zone status data. Based on the status data, it determines whether the fire zone needs to be replenished with multiphase foam. If replenishment is required, a tracked intelligent robot replenishes the target area with multiphase foam. The flexible foam delivery pipeline has built-in temperature and oxygen concentration sensors. When the sensors detect that the local temperature in the fire zone is higher than a preset threshold, the multiphase foam replenishment operation is triggered.

[0035] Specifically, the flexible foam delivery pipeline is pre-installed with temperature and oxygen concentration sensors. These sensors continuously collect real-time data on the fire zone, including temperature conditions in different areas and oxygen concentration distribution. The collected fire zone data is used to analyze whether the fire zone needs additional multiphase foam. When the temperature sensor detects that the temperature in a local area of ​​the fire zone exceeds a preset threshold, it directly triggers the multiphase foam injection operation. At this time, the tracked intelligent robot will carry multiphase foam and accurately inject it into the target area based on the temperature anomaly area (i.e., the target area) located by the sensor, taking into account the fire zone terrain and crack distribution. This ensures that the fire zone is always in an effective flame-retardant state and avoids reignition due to local temperature rise.

[0036] A multiphase foam flame-retardant fire extinguishing system for coalfield fire zones includes an intelligent detection module, a multiphase foam preparation module, a precision delivery module, and a real-time monitoring and feedback module; The intelligent reconnaissance module includes a drone equipped with an infrared thermal imaging sensor and a gas sensor, as well as a tracked intelligent robot with terrain adaptation and autonomous obstacle avoidance capabilities. The intelligent reconnaissance module is used to generate a three-dimensional heat map of the fire zone. The multiphase foam preparation module includes a mixed gas phase generator, a liquid phase emulsification tank, a solid phase dispersion tank, and a high-shear emulsifier. The mixed gas phase generator is used to prepare a mixed gas of nitrogen and carbon dioxide. The liquid phase emulsification tank is used to mix bio-based surfactants and temperature-responsive epoxy resin emulsions. The solid phase dispersion tank is used to store composite flame-retardant particles. The high-shear emulsifier is used to mix the gas phase, liquid phase, and solid phase to form multiphase foam. The precision delivery module includes a flexible foam delivery pipeline, a tracked pipe laying robot, and a foam booster pump. The tracked pipe laying robot is used to lay the flexible foam delivery pipeline, and the foam booster pump is used to adjust the injection pressure of the multiphase foam. The real-time monitoring and feedback module includes a temperature sensor, an oxygen concentration sensor, a data transmission terminal, and a central control platform. The temperature sensor and the oxygen concentration sensor are built into the flexible foam delivery pipeline. The data transmission terminal is used to transmit the data collected by the sensors, and the central control platform is used to determine whether to trigger a replenishment operation based on the data.

[0037] Specifically, the multiphase foam flame-retardant fire extinguishing system in this coalfield fire area achieves efficient fire suppression through the coordinated operation of four functional modules. The intelligent reconnaissance module relies on drones equipped with infrared thermal imaging sensors and gas sensors, as well as tracked intelligent robots with terrain adaptation and autonomous obstacle avoidance capabilities, to collect fire area data and generate a three-dimensional thermal map of the fire area, providing accurate data for subsequent operations. The multiphase foam preparation module uses a mixed gas phase generator to prepare a mixture of nitrogen and carbon dioxide, mixes bio-based surfactants and temperature-responsive epoxy resin emulsion in a liquid phase emulsification tank, stores composite flame-retardant particles in a solid phase dispersion tank, and then passes them through a high-shear emulsifier. The system mixes gaseous, liquid, and solid phases to form multiphase foam. The precision delivery module uses a tracked pipe-laying robot to lay flexible foam delivery pipelines and regulates the injection pressure of the multiphase foam through a foam booster pump to ensure precise delivery of the foam to the fire zone. The real-time monitoring and feedback module collects fire zone data through temperature and oxygen concentration sensors built into the flexible foam delivery pipelines and transmits the data to the central control platform via a data transmission terminal. The central control platform then determines whether to trigger the multiphase foam replenishment operation based on the data. The four modules work together to form a complete fire extinguishing closed loop of "reconnaissance-preparation-delivery-monitoring", which is adapted to the complex environment of coalfield fire zones to achieve efficient flame-retardant fire extinguishing.

[0038] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant technology, characterized in that, Includes the following steps: S1. Prepare a multiphase foam, wherein the multiphase foam comprises a gas phase, a liquid phase and a solid phase, wherein the gas phase is a mixture of nitrogen and carbon dioxide, the liquid phase is based on a bio-based surfactant and compounded with a temperature-responsive epoxy resin emulsion, and the solid phase is composite flame-retardant particles. S2. Conduct reconnaissance of coalfield fire areas by using drones equipped with infrared thermal imaging sensors and gas sensors to scan the temperature distribution and crack locations of the fire areas and generate a three-dimensional thermal map of the fire areas. S3. Based on the three-dimensional thermal map of the fire zone, flexible foam delivery pipelines are dynamically laid out in the high-temperature core area and fissure channels of the fire zone by a tracked intelligent robot. S4. The multiphase foam prepared in step S1 is injected into the fire zone through the flexible foam delivery pipeline. When the multiphase foam comes into contact with the preset temperature in the fire zone, the temperature-responsive epoxy resin emulsion in the liquid phase is triggered to cure, fixing the solid-phase composite flame-retardant particles to the surface of the coal body and the cracks. S5. The sensor built into the flexible foam delivery pipeline collects the fire zone status data in real time. Based on the status data, it is determined whether the fire zone needs to be replenished with multiphase foam. If replenishment is required, multiphase foam is replenished to the target area by a tracked intelligent robot.

2. The method for extinguishing coalfield fires using multiphase foam flame retardant as described in claim 1, characterized in that, In S1, the volume ratio of nitrogen to carbon dioxide in the gas phase is 7:3, the bio-based surfactant is tea saponin, and the critical curing temperature of the temperature-responsive epoxy resin emulsion is 80-120℃.

3. The method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant, as described in claim 1, is characterized in that... In step S1, the composite flame-retardant particles are composed of nano-magnesium hydroxide and expandable graphite, wherein the nano-magnesium hydroxide has a particle size of 50-100 nm.

4. The method for extinguishing coalfield fires using multiphase foam flame retardant foam according to claim 1, characterized in that, In S1, the specific process for preparing multiphase foam is as follows: first, the liquid phase and the solid phase composite flame retardant particles are placed in an emulsification device for ultrasonic dispersion, then the gas phase is introduced into the dispersed mixture, and finally, the mixture is processed by a high-shear emulsifier to form multiphase foam.

5. The method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant, as described in claim 1, is characterized in that... In step S2, when the UAV scans the fire zone, it simultaneously collects oxygen concentration data of the fire zone. The three-dimensional thermal map of the fire zone includes the fire zone temperature value, crack size, and oxygen concentration distribution information.

6. The method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant, as described in claim 1, is characterized in that... In S3, the tracked intelligent robot has terrain adaptation and autonomous obstacle avoidance functions. When laying flexible foam delivery pipelines, the pipeline laying spacing is adjusted according to the size of the cracks in the fire zone.

7. The method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant, as described in claim 1, is characterized in that... In step S4, a high-pressure injection method is used when injecting multiphase foam into the fire zone, and the injection pressure is dynamically adjusted by a booster device according to the depth of the cracks in the fire zone.

8. The method for extinguishing fires in coalfield fire zones using multiphase foam flame retardant, as described in claim 1, is characterized in that... In step S5, the sensors built into the flexible foam delivery pipeline are a temperature sensor and an oxygen concentration sensor. When the sensor detects that the local temperature in the fire zone is higher than a preset threshold, it triggers the operation of replenishing multiphase foam.

9. A multiphase foam flame-retardant fire extinguishing system for coalfield fire zones, comprising a multiphase foam flame-retardant fire extinguishing method for coalfield fire zones according to any one of claims 1-8, characterized in that, It includes an intelligent detection module, a multiphase foam preparation module, a precision delivery module, and a real-time monitoring and feedback module; The intelligent reconnaissance module includes a drone equipped with an infrared thermal imaging sensor and a gas sensor, as well as a tracked intelligent robot with terrain adaptation and autonomous obstacle avoidance capabilities. The intelligent reconnaissance module is used to generate a three-dimensional heat map of the fire zone. The multiphase foam preparation module includes a mixed gas phase generator, a liquid phase emulsification tank, a solid phase dispersion tank, and a high-shear emulsifier. The mixed gas phase generator is used to prepare a mixed gas of nitrogen and carbon dioxide. The liquid phase emulsification tank is used to mix bio-based surfactants and temperature-responsive epoxy resin emulsions. The solid phase dispersion tank is used to store composite flame-retardant particles. The high-shear emulsifier is used to mix the gas phase, liquid phase, and solid phase to form multiphase foam. The precision delivery module includes a flexible foam delivery pipeline, a tracked pipe laying robot, and a foam booster pump. The tracked pipe laying robot is used to lay the flexible foam delivery pipeline, and the foam booster pump is used to adjust the injection pressure of the multiphase foam. The real-time monitoring and feedback module includes a temperature sensor, an oxygen concentration sensor, a data transmission terminal, and a central control platform. The temperature sensor and the oxygen concentration sensor are built into the flexible foam delivery pipeline. The data transmission terminal is used to transmit the data collected by the sensor. The central control platform is used to determine whether to trigger a refill operation based on the data.

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