Construction of an early warning indicator and early warning method for mine conveyor belt fire

Abstract

The present invention relates to the technical field of mine fire early warning, and provides a method for constructing an early warning indicator for a mine conveyor belt fire and an early warning method, comprising the following steps: verifying the feasibility of using HCl gas as a signature gas for early warning of a conveyor belt fire through energy spectrum testing and thermal decomposition experiments; obtaining a TG-DTG curve; establishing an early warning indicator and a multi-level warning threshold; constructing a system architecture and interface; deploying monitoring equipment; establishing data sharing and establishing a data sharing port; developing a monitoring data analysis module; mapping the HCl gas concentration, CO gas concentration, and conveyor belt temperature field in the conveyor belt lane; establishing a conveyor belt fire hazard zone; and sending an alarm signal to the outside world through an audible and visual alarm and activating a connected linkage controller. This solution solves the problem of the insensitivity of existing mine fire early warning systems, which results in the inability to achieve early warning, by selecting signature gas detection with high sensitivity and regularity.

Description

Technical Field

[0001] The present invention relates to the technical field of mine fire early warning, and in particular to a mine conveyor belt fire early warning indicator construction and early warning method. Background Art

[0002] Mine fires are a major natural disaster in coal mining operations. They can destroy significant quantities of coal resources and equipment, generate high-temperature smoke and toxic gases, and pose a serious threat to underground personnel. As mines extend deeper, conveyor belt lengths increase, increasing the threat of conveyor belt fires. Effective prevention is crucial for ensuring safe mine production. Therefore, early warning systems based on signature gas detection are crucial.

[0003] Most existing early warning systems for mine conveyor belt fires use CO as a signature gas, and the alarm concentration of a CO sensor is generally 24 ppm. When a conveyor belt fire occurs, it takes a long time for the CO gas concentration to rise to this concentration. Belt conveyors are generally installed in tunnels with high air volume. Due to the dilution effect of the air volume, even if the conveyor belt has caught fire, only trace concentrations of CO gas may appear. This results in the serious consequence that the carbon monoxide sensor cannot provide early warning in an accident. Summary of the Invention

[0004] In order to solve the problems existing in the background technology, the present invention proposes a mine conveyor belt fire early warning indicator construction and warning method, and selects a signature gas detection with high sensitivity and regularity to solve the problem that the existing mine fire warning system is insensitive and thus cannot achieve early warning. Through early warning, fire extinguishing measures can be taken in time to prevent the accident from expanding and reduce the impact on the overall safety of the mine.

[0005] To achieve the above object, the present invention adopts the following scheme, including the following steps:

[0006] Step 1: Construct conveyor belt early warning indicators through experiments

[0007] Step 1.1 Select conveyor belts and coal from different locations in the mine as experimental samples;

[0008] Step 1.2: performing an energy spectrum test on the conveyor belt and coal of the experimental sample to verify the feasibility of HCl gas as a characteristic gas for early warning of conveyor belt fire based on the elemental composition and content of the experimental sample;

[0009] In step 1.3, the conveyor belt of the experimental sample is tested for escaping gas during the thermal decomposition process. The absorbance integral of the conveyor belt's infrared spectrum data is measured, and the FGP curve of the escaping gas is obtained to analyze the characteristics of the escaping gas and further verify the feasibility of HCl gas as a characteristic gas for early warning of conveyor belt fires. In step 1.4, a combustion experiment of the conveyor belt and coal mixed experimental sample is conducted in an air atmosphere to obtain a TG-DTG curve.

[0010] Step 1.5: First, based on the thermal decomposition experiment, the temperature of the conveyor belt when HCl gas is initially detected is used as the early warning threshold. Then, based on the TG-DTG curve, the combustion characteristics of the coal and conveyor belt mixed experimental sample are obtained to establish a multi-level warning threshold.

[0011] Step 2: Build a conveyor belt fire early warning system

[0012] Step 2.1 Build system architecture and interface;

[0013] Step 2.2: Deploy monitoring equipment above the conveyor belt and on the rollers for detecting HCl gas concentration, CO gas concentration, and monitoring the conveyor belt temperature;

[0014] Step 2.3: Connecting a data acquisition module to the monitoring device to collect data on HCl gas concentration, CO gas concentration, and conveyor belt temperature from the monitoring device in real time; establishing a data sharing port to enable data exchange and sharing with the sound and light alarm and linkage controller;

[0015] Step 2.4: Connect the developed monitoring data analysis module to the data acquisition module to automatically analyze and process the collected data and extract key features;

[0016] Step 2.5: Establish a spatial rectangular coordinate system with the conveyor belt arranged along the conveying direction as the X-axis, time as the Y-axis, and the HCl gas concentration, CO gas concentration, and conveyor belt temperature as the Z-axis, and draw a graph of the HCl gas concentration, CO gas concentration, and conveyor belt temperature field in the conveyor belt lane;

[0017] In step 2.6, in the field map, areas where the conveyor belt temperature is greater than the early warning threshold or where the HCl gas concentration is greater than the HCl gas concentration value corresponding to the early warning threshold are defined as conveyor belt fire hazard areas, and the conveyor belt fire hazard areas are divided into different levels according to different warning thresholds. In step 2.7, when a fire hazard area appears in the field map, an alarm signal is sent to the outside world through the sound and light alarm and the connected linkage controller is activated.

[0018] Furthermore, in the experimental samples, the conveyor belt adopts a rubber surface solid core flame retardant conveyor belt PVG sample.

[0019] Furthermore, in step 1.2, when the experimental samples were subjected to energy spectrum testing, the conveyor belt used PVG block samples and the coal used coal powder samples; the energy spectrum testing showed that the coal was a functional group composed of two elements, C and O, and the signal intensity peak of the Cl element in the conveyor belt PVG was more obvious.

[0020] Furthermore, in step 1.3, the thermal decomposition experiment adopts a heating rate of 10K / min and a temperature range of 30°C to 800°C. The evolved gas test adopts a thermogravimetric-infrared analyzer. The characteristic law of the evolved gas is as follows: HCl gas begins to be generated when the thermal decomposition temperature is about 170°C, the main gas product before the thermal decomposition temperature is HCl before 280°C, the amount of HCl gas generated is the largest when the thermal decomposition temperature is 270°C to 290°C, and the maximum escape amount of CO and CO2 corresponds to a temperature exceeding 460°C.

[0021] Furthermore, the combustion experiment in step 1.4 includes three stages: an initial stage when the conveyor belt temperature is 30°C to 211.58°C, during which HCl gas is generated; a decomposition and combustion stage when the conveyor belt temperature is 211.58°C to 633.43°C, wherein the conveyor belt temperature is 286.51°C, a large amount of HCl gas is generated, and the peak temperature of the second region is 438.31°C, during which HCl gas is generated while a large amount of CO gas is generated; and a burnout stage when the conveyor belt temperature exceeds 633.43°C, during which the gas generated is negligible.

[0022] Furthermore, in step 1.5, the conveyor belt temperature when HCl gas is initially detected is 170° C., and the multi-level warning threshold includes a first-level warning threshold, a second-level warning threshold, and a third-level warning threshold. The first-level warning threshold range is greater than or equal to 250° C. and less than 350° C., the second-level warning temperature preset threshold range is greater than or equal to 350° C. and less than 500° C., and the third-level warning temperature preset threshold range is greater than or equal to 500° C.

[0023] Furthermore, in step 2.1, the system architecture and interface include the system functions and performance requirements determined with the user, the system outline design diagram and the user interface design diagram.

[0024] Furthermore, in step 2.4, the key features include the changing trend of gas concentration and the changing pattern of temperature.

[0025] The beneficial effects of the present invention are as follows: This solution verifies the feasibility of HCl gas as a signature gas for early warning of conveyor belt fires through energy spectrum testing and thermal decomposition experiments, and constructs an early warning threshold using the HCl gas generated by the conveyor belt as the dominant factor. Then, based on the TG-DTG curve, the law of change of HCl gas overflow with temperature is obtained to establish a multi-level warning threshold. This hierarchical warning method can help relevant personnel better judge the severity of fire risks, rationally allocate resources, and take effective countermeasures, thereby improving the safety of the conveyor belt system and reducing the occurrence and losses of fire accidents. On the other hand, this solution constructs a conveyor belt fire early warning system based on the conveyor belt early warning indicators, which can detect signs of fire in a timely manner, buy valuable time for personnel evacuation, reduce the risk of casualties, and through early warning, timely take fire extinguishing measures to reduce property losses, prevent the expansion of accidents, and reduce the impact on the overall safety of the mine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Flowchart of the present invention;

[0027] Figure 2 is the surface element signal intensity of the coal powder experimental sample in the embodiment of the present invention;

[0028] Figure 3 is the surface element signal intensity of the PVG bulk experimental sample in the embodiment of the present invention;

[0029] Figure 4 This is a FGP curve diagram of HCl gas released during the pyrolysis of PVG conveyor belt according to an embodiment of the present invention;

[0030] Figure 5 This is a FGP curve diagram of CO gas released during the pyrolysis of PVG conveyor belt according to an embodiment of the present invention;

[0031] Figure 6 This is a schematic diagram of the layout of the monitoring equipment according to an embodiment of the present invention;

[0032] Figure 7 This is a TG-DTG curve diagram of the combustion experiment of the embodiment of the present invention.

[0033] Numbers in the figure: 1. Monitoring equipment; 2. Conveyor belt; 3. Coal; 4. Roller. DETAILED DESCRIPTION

[0034] In order to make the present invention clearer and more understandable, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the given embodiment is only one implementation method and does not represent all embodiments.

[0035] Example 1

[0036] Combine Figure 1 This embodiment provides a method for constructing early warning indicators and early warning methods for conveyor belt fires in mines, including the following steps:

[0037] Step 1: Construct early warning indicators for conveyor belt 2 through experiments.

[0038] Step 1.1 In order to ensure the accuracy of the experiment, conveyor belts 2 and coal 3 from different locations in the mine are selected as experimental samples. Among the experimental samples, conveyor belt 2 adopts a rubber-surfaced solid-core flame-retardant conveyor belt 2 PVG sample.

[0039] Step 1.2: Energy spectrum testing was performed on the conveyor belt 2 and coal 3 of the experimental sample to verify the feasibility of HCl gas as a characteristic gas for early warning of fire on the conveyor belt 2 based on the elemental composition and content of the experimental sample. When the energy spectrum test was performed on the experimental sample, PVG block sample was used for the conveyor belt 2 and coal 3 powder sample was used for the coal 3; the energy spectrum test showed that: Figure 2 It can be seen that the coal 3 is a functional group composed of two elements, C and O. Figure 3 It can be seen that the signal intensity peak of the Cl element in the PVG of conveyor belt 2 is relatively obvious. Therefore, based on the elemental composition and content, it can be proved that HCl gas can be used as a signature gas for early warning of fire on conveyor belt 2.

[0040] In step 1.3, the conveyor belt 2 of the experimental sample is tested for escaping gas during the thermal decomposition process, and the absorbance integral of the infrared spectrum data of the conveyor belt 2 is measured to obtain the FGP curve of the escaping gas, such as Figure 4 、 Figure 5 , in order to analyze the characteristics of the escaping gas and further verify the feasibility of HCl gas as a signature gas for early warning of conveyor belt 2 fire.

[0041] The thermal decomposition experiment used a heating rate of 10K / min and a temperature range of 30°C to 800°C. The evolved gas was tested using a thermogravimetric-infrared analyzer. The thermal decomposition experiment revealed the following characteristics of the evolved gas: HCl gas began to be produced at a thermal decomposition temperature of approximately 170°C. HCl was the primary gaseous product before the thermal decomposition temperature reached 280°C. HCl gas production reached its maximum at thermal decomposition temperatures between 270°C and 290°C, while the maximum CO and CO2 emissions occurred at temperatures exceeding 460°C. HCl was the primary product before 280°C, while CO and CO2 emissions reached their maximum levels at temperatures exceeding 460°C. HCl was the primary product before 280°C, while CO and CO2 production were relatively small. As the temperature continued to rise, the thermal decomposition of conveyor belt 2 began to produce large amounts of CO and CO2. Therefore, HCl gas can be considered a signature gas for a fire on conveyor belt 2.

[0042] Step 1.4: Carry out a combustion test of the mixed experimental sample of conveyor belt 2 and coal 3 in air atmosphere to obtain the TG-DTG curve, such as Figure 7;

[0043] The combustion process of the experimental sample of mixing coal 3 with conveyor belt 2 can be divided into three stages: preparation stage, decomposition and combustion stage, and burnout stage.

[0044] (1) Preparation stage

[0045] The experimental start temperature of conveyor belt 2 rose from 30°C to 211.58°C during the preparation phase. During this phase, conveyor belt 2 lost only 1.34% of its mass, indicating relatively minor damage, likely just minor surface wear or material loss. The performance and service life of conveyor belt 2 were likely minimally impacted during this phase. HCl gas production also began.

[0046] (2) Decomposition and combustion stage

[0047] The decomposition and combustion phase of Conveyor Belt 2, with temperatures ranging from 211.58°C to 633.43°C, represents the period of decomposition and combustion. During this phase, Conveyor Belt 2 experienced a weight loss of 50.84%, indicating that damage to Conveyor Belt 2 was gradually increasing. This high weight loss rate may indicate significant structural damage to Conveyor Belt 2, a decrease in the material's strength and wear resistance, and a potential safety hazard. The DTG curve for this phase shows two regions with rapid weight loss rates. The first region has a peak temperature of 286.51°C, a weight loss rate of 6.15% / min, and produces significant amounts of HCl gas. The second region has a peak temperature of 438.31°C, a weight loss rate of 1.32% / min, and produces both HCl and significant amounts of CO gas.

[0048] (3) Burnout stage

[0049] The burnout stage occurs when the temperature of conveyor belt 2 exceeds 633.43°C. According to the TG curve at this stage, the mass of the mixed sample decreases slightly or remains basically unchanged, and the final combustion residue reaches 47.82%, and basically no gas is released.

[0050] In step 1.5, based on the combustion experiment, the temperature of conveyor belt 2 at the time of preliminary detection of HCl gas is first used as the early warning threshold. Then, based on the combustion characteristics of the coal and conveyor belt mixed experimental sample obtained from the TG-DTG curve, a multi-level warning threshold is established. Based on step 1.3, the temperature of conveyor belt 2 at the time of preliminary detection of HCl gas was 170°C. In the experiment, an HCl sensor was used, and the alarm concentration was set to a trace concentration. When HCl gas was detected, the temperature of conveyor belt 2 had reached 170°C, so it can be assumed that conveyor belt 2 is about to or has already entered the bond breaking and cracking stage. Therefore, the temperature of conveyor belt 2 of 170°C is used as the early warning threshold.

[0051] Based on the TG-DTG curve rule in step 1.4, the multi-level warning threshold is set to a three-level warning threshold, including a first-level warning threshold range of greater than or equal to 250°C and less than 350°C, a second-level warning temperature preset threshold range of greater than or equal to 350°C and less than 500°C, and a third-level warning temperature preset threshold range of greater than or equal to 500°C.

[0052] It is important to understand that in the process of experimentally constructing early warning indicators for conveyor belt 2, especially in the thermal decomposition experiments in step 1.3 and the combustion experiments in step 1.4, it is necessary to analyze the characteristics and influencing factors of each stage by combining the stage characteristics of gas generation with the integral method to calculate the oxidation kinetics and derive the reaction mechanism function. The specific algorithm formula is as follows:

[0053]

[0054] Wherein, α is the conversion rate of the material during oxidation and decomposition, in %; t is the time of oxidation and decomposition of the material, in s; A is the reaction pre-exponential factor, in s -1 ; E is the apparent activation energy, unit is J / mol; R is the thermodynamic gas constant, unit is J / (mol·K); T is the temperature, unit is K; f(α) is the reaction kinetic mechanism function.

[0055]

[0056] Where W0 is the initial mass of the sample, in g; W t is the mass of the sample at time t, in g; W t is the mass of the sample at the end moment, in g.

[0057] f(α) can be defined as: f(α) = (1-α) n

[0058] Combining the above formulas, we can get:

[0059] Integrating both sides, we get:

[0060] Where T0 is the initial temperature, in K.

[0061] When the first-order chemical kinetic model is used, the correlation coefficient is the largest, and the oxidation reaction between coal and conveyor belt is considered to be a first-order chemical reaction, that is, n = 1. The approximate solution is obtained using the Coats-Redfern integral formula:

[0062]

[0063] make

[0064] The above formula is transformed into: y=a+bx

[0065] Activation energy is an important indicator of the intensity of a material's combustion. Using the formula for statistical analysis and data fitting, we can obtain the fitting coefficient and a straight line with a slope of b and an intercept of a. The slope of the line can be used to determine the activation energy E under the given conversion rate, and the intercept can be used to determine the pre-exponential factor A corresponding to the activation energy E.

[0066] Step 2: Build a conveyor belt 2 fire early warning system

[0067] Step 2.1 Build the system architecture and interface; the system architecture and interface include the system functions and performance requirements determined with the user, the system outline design diagram and the user interface design diagram.

[0068] Step 2.2 Figure 6 Monitoring equipment 1 is installed above conveyor belt 2 and on rollers 4 to detect HCl and CO gas concentrations and monitor the temperature of conveyor belt 2. HCl and CO gas concentrations can be detected using combustible gas sensors, while the temperature of conveyor belt 2 can be detected using infrared temperature sensors. The combustion characteristics of experimental samples of coal 3 mixed with conveyor belt 2 indicate that CO gas concentration also needs to be monitored in the later stages of a fire. This is essential for understanding the extent of conveyor belt combustion and establishing a multi-level early warning system.

[0069] In step 2.3, a data acquisition module is developed, connected to the monitoring device 1, to collect real-time data on HCl gas concentration, CO gas concentration, and conveyor belt 2 temperature from the monitoring device 1. A data sharing port is also established to enable data exchange and sharing with the audible and visual alarms and the linkage controller. Through timely data exchange and sharing, when the fire early warning system detects an abnormality, the information can be rapidly transmitted to the audible and visual alarms and the linkage controller. The audible and visual alarms can immediately issue an alarm signal, prompting personnel to evacuate, while the linkage controller automatically activates relevant firefighting equipment, such as the fire extinguishing system and smoke exhaust system. This significantly improves fire response speed and saves valuable time to minimize fire damage. Furthermore, data sharing enables the various firefighting equipment to work together, forming an integrated whole. This allows each device to function more effectively and enhances the overall firefighting system's prevention and control capabilities. For example, the accurate information provided by the early warning system can help the linkage controller more precisely control the activation timing and operating parameters of firefighting equipment, improving firefighting and smoke exhaust effectiveness.

[0070] Step 2.4: Develop a monitoring data analysis module connected to the data acquisition module to automatically analyze and process the collected data, extracting key features, such as gas concentration trends and temperature patterns. By analyzing these key features, we can better understand the information contained in the monitoring data, provide strong support for decision-making, and promptly identify potential problems and anomalies.

[0071] In step 2.5, establish a spatial rectangular coordinate system with conveyor belt 2, which runs along the conveying direction, as the X-axis, time as the Y-axis, and the HCl gas concentration, CO gas concentration, and temperature of conveyor belt 2 as the Z-axis. Plot the HCl gas concentration, CO gas concentration, and temperature field of conveyor belt 2 in the laneway of conveyor belt 2. This field plot can be created using professional plotting software such as Matlab, Origin, or Python plotting libraries (e.g., matplotlib). Color mapping can be added to the field plot to indicate concentration or temperature, as needed.

[0072] In step 2.6, in the field map, areas where the conveyor belt temperature exceeds the early warning threshold or where the HCl gas concentration exceeds the HCl gas concentration corresponding to the early warning threshold are defined as conveyor belt fire hazard zones. The conveyor belt fire hazard zones are differentiated into different levels according to different warning thresholds. Preferably, the different levels can be distinguished by color to make them more visible.

[0073] When monitored parameter values ​​reach the early warning threshold, it indicates a potential fire risk, necessitating attention and preventative measures such as increased inspections and investigations for potential hazards. When parameter values ​​exceed higher warning thresholds, the fire risk increases further, and more urgent measures may be necessary, such as activating emergency plans and evacuating personnel. This tiered warning approach helps personnel better assess the severity of fire risks, rationally allocate resources, and implement effective countermeasures, thereby improving the safety of the Conveyor Belt 2 system and reducing the occurrence and losses of fire accidents.

[0074] Step 2.7: When a fire hazard area appears in the on-site map, an alarm signal is sent to the outside world through the sound and light alarm and the connected linkage controller is activated to take relevant measures.

[0075] The above detailed description of the specific embodiments of the present invention is provided in conjunction with the drawings, but the present invention is not limited to the described embodiments. It is apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments may be made without departing from the principles and spirit of the present invention, and these changes and modifications still fall within the scope of protection of the present invention.

Claims

1. A mine conveyor belt fire early warning indicator construction and early warning method, characterized in that: The steps include: Step 1: Construct conveyor belt early warning indicators through experiments Step 1.1 Select conveyor belts and coal from different locations in the mine as experimental samples; Step 1.2: performing an energy spectrum test on the conveyor belt and coal of the experimental sample to verify the feasibility of HCl gas as a characteristic gas for early warning of conveyor belt fire based on the elemental composition and content of the experimental sample; In step 1.3, the conveyor belt of the experimental sample is tested for escaping gas during the thermal decomposition process. The absorbance integral of the conveyor belt's infrared spectrum data is measured, and the FGP curve of the escaping gas is obtained to analyze the characteristics of the escaping gas and further verify the feasibility of HCl gas as a characteristic gas for early warning of conveyor belt fires. In step 1.4, a combustion experiment of the conveyor belt and coal mixed experimental sample is conducted in an air atmosphere to obtain a TG-DTG curve. Step 1.5: First, based on the thermal decomposition experiment, the temperature of the conveyor belt when HCl gas is initially detected is used as the early warning threshold. Then, based on the TG-DTG curve, the combustion characteristics of the coal and conveyor belt mixed experimental sample are obtained to establish a multi-level warning threshold. Step 2: Build a conveyor belt fire early warning system Step 2.1 Build system architecture and interface; Step 2.2: Deploy monitoring equipment above the conveyor belt and on the rollers for detecting HCl gas concentration, CO gas concentration, and monitoring the conveyor belt temperature; Step 2.3: Connecting a data acquisition module to the monitoring device to collect data on HCl gas concentration, CO gas concentration, and conveyor belt temperature from the monitoring device in real time; establishing a data sharing port to enable data exchange and sharing with the sound and light alarm and linkage controller; Step 2.4: Connect the developed monitoring data analysis module to the data acquisition module to automatically analyze and process the collected data and extract key features; Step 2.5: Establish a spatial rectangular coordinate system with the conveyor belt arranged along the conveying direction as the X-axis, time as the Y-axis, and the HCl gas concentration, CO gas concentration, and conveyor belt temperature as the Z-axis, and draw a graph of the HCl gas concentration, CO gas concentration, and conveyor belt temperature field in the conveyor belt lane; In step 2.6, in the field map, areas where the conveyor belt temperature is greater than the early warning threshold or where the HCl gas concentration is greater than the HCl gas concentration value corresponding to the early warning threshold are defined as conveyor belt fire hazard areas, and the conveyor belt fire hazard areas are divided into different levels according to different warning thresholds. In step 2.7, when a fire hazard area appears in the field map, an alarm signal is sent to the outside world through the sound and light alarm and the connected linkage controller is activated.

2. The method for constructing early warning indicators and warning of conveyor belt fire in a mine according to claim 1, characterized in that: In the experimental samples, the conveyor belt adopts a rubber-surfaced solid-core flame-retardant conveyor belt PVG sample.

3. The method for constructing early warning indicators and warning of mine conveyor belt fires according to claim 2, characterized in that: In step 1.2, when the experimental samples were subjected to energy spectrum testing, the conveyor belt used PVG block samples and the coal used coal powder samples; the energy spectrum testing showed that the coal was a functional group composed of two elements, C and O, and the signal intensity peak of the Cl element in the conveyor belt PVG was obvious.

4. The method for constructing early warning indicators and warning of conveyor belt fire in a mine according to claim 2, characterized in that: In the step 1.3, the thermal decomposition experiment adopts a heating rate of 10K / min and a temperature range of 30°C to 800°C. The evolved gas is tested using a thermogravimetric-infrared analyzer. The characteristics of the evolved gas are as follows: HCl gas begins to be generated when the thermal decomposition temperature is about 170°C, the main gas product before the thermal decomposition temperature is HCl is HCl, the amount of HCl gas generated is the largest when the thermal decomposition temperature is 270°C to 290°C, and the maximum escape amount of CO and CO2 corresponds to a temperature exceeding 460°C.

5. The method for constructing early warning indicators and warning of conveyor belt fire in a mine according to claim 2, characterized in that: The combustion experiment in step 1.4 includes three stages: an initial stage when the conveyor belt temperature is between 30°C and 211.58°C, during which HCl gas is generated; a decomposition and combustion stage when the conveyor belt temperature is between 211.58°C and 633.43°C, during which a large amount of HCl gas is generated when the conveyor belt temperature is 286.51°C; and a large amount of CO gas is generated when the conveyor belt temperature is 438.31°C; and a burnout stage when the conveyor belt temperature exceeds 633.43°C, during which the generated gas is negligible.

6. The method for constructing early warning indicators and warning of conveyor belt fire in a mine according to claim 2, characterized in that: In step 1.5, the conveyor belt temperature when HCl gas is initially detected is 170° C., and the multi-level warning threshold includes a first-level warning threshold, a second-level warning threshold, and a third-level warning threshold. The first-level warning threshold range is greater than or equal to 250° C. and less than 350° C., the second-level warning temperature preset threshold range is greater than or equal to 350° C. and less than 500° C., and the third-level warning temperature preset threshold range is greater than or equal to 500° C.

7. A mine conveyor belt fire early warning indicator construction and early warning method according to claim 1, Its characteristics are: In step 2.1, the system architecture and interface include the system functions and performance requirements determined with the user, the system outline design diagram and the user interface design diagram.

8. The method for constructing early warning indicators and warning of conveyor belt fire in a mine according to claim 1, characterized in that: In step 2.4, the key features include the changing trend of gas concentration and the changing pattern of temperature.

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