A method for detecting a coalfield fire zone

Abstract

The application discloses a coalfield fire area detection method, comprising the following steps: collecting unburned coal from a coalfield and calculating the volume of the collected coal to obtain an experimental volume; putting the coal into an experimental device to simulate coalfield fire area combustion, collecting first combustion data; measuring the coalfield combustion volume and second combustion data; and obtaining the coalfield combustion degree through the first combustion data, the second combustion data, the experimental volume and the combustion volume. The method simulates the coalfield fire area combustion by collecting coal from the coalfield, obtains simulated combustion experiment data from the beginning of the combustion of the coal to the end, and then performs proportional calculation by measuring the volume of the coalfield fire area and the volume of the collected coal, so that the data of the coalfield fire area is brought into the simulated combustion experiment data to obtain the coalfield combustion degree, which is beneficial to the next step of coalfield fire area treatment.

Description

Technical Field

[0001] This invention belongs to the field of coalfield detection technology, and in particular relates to a method for detecting coalfield fire zones. Background Technology

[0002] The main methods used domestically and internationally for coalfield fire detection include borehole thermometry, magnetic methods, and radon measurement. Borehole thermometry involves drilling into the fire zone and then using thermocouples, infrared thermometers, and other temperature measuring instruments to measure the temperature inside the borehole. The distribution and development of the fire zone are determined based on the borehole temperature. This method is the most direct, but due to the poor thermal conductivity of coal and rock, accurate detection requires dense drilling throughout the detection area (generally with a hole spacing of less than 10m), resulting in a large workload and high cost. Magnetic methods delineate the fire zone boundary by detecting the remanent magnetization generated by the scorched rock in the fire zone. However, scorched rock generally only produces significant remanent magnetization at temperatures above 400℃. In areas below 400℃, the low remanent magnetization leads to poor detection accuracy; therefore, this method cannot meet the detection requirements for areas below 400℃. Radon detection methods determine the distribution of coalfield fire zones by detecting radon levels in the detection area, assuming that higher radon concentrations indicate more severe fire development. However, in actual detection processes, radon levels are significantly affected by factors such as stratum thickness, water content, and fracture development in the detection area, resulting in low detection accuracy. These factors make it difficult to determine the degree of coalfield combustion. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for detecting coalfield fire zones, thereby resolving the issue that existing detection methods are limited by various factors and cannot accurately detect the degree of coalfield combustion.

[0004] To achieve the above objectives, the present invention provides a method for detecting coalfield fire zones, comprising the following steps:

[0005] Unburned coal was collected from the coalfield, and the volume of the collected coal was calculated to obtain the experimental volume;

[0006] The coal was placed into an experimental device to simulate combustion in a coalfield fire zone, and the first combustion data was collected.

[0007] Measure the volume of coalfield combustion and secondary combustion data;

[0008] The degree of coalfield combustion is obtained by using the first combustion data, the second combustion data, the experimental volume, and the combustion volume.

[0009] Preferably, the method for collecting unburned coal includes:

[0010] Measure the depth of the coalfield, and then collect coal from the upper, middle and lower parts of the coal seam from four directions of the coalfield fire zone. When collecting coal, it is necessary to collect coal that has not been affected by the fire zone.

[0011] Preferably, the method for collecting the first combustion data includes:

[0012] After the coal is heated, the gas inside the experimental apparatus is collected using a gas collection device, and the gas content is determined experimentally. At the same time, the density change of the coal during the experiment is measured using a radar device.

[0013] Preferably, the method for experimentally determining the gas content includes:

[0014] Sulfur dioxide concentration was monitored using ultraviolet absorption method;

[0015] Carbon dioxide concentration was monitored using infrared absorption.

[0016] Preferably, the method for monitoring sulfur dioxide concentration by ultraviolet absorption includes:

[0017] Ultraviolet (UV) emission and reception devices are installed at both ends of the gas collection device, and the installation distance of the UV emission and reception devices is measured. After the UV emission device emits UV light, it is absorbed by sulfur dioxide, and the remaining UV light after absorption is collected by the UV reception device. The sulfur dioxide concentration is calculated based on the intensity of the emitted UV light, the intensity of the remaining UV light, and the installation distance.

[0018] Preferably, the method for monitoring carbon dioxide concentration by infrared absorption includes:

[0019] Infrared transmitters and receivers are installed at both ends of the gas collection device, and the installation distance between the infrared transmitters and receivers is measured. The infrared rays emitted by the infrared transmitters are absorbed by carbon dioxide, and the remaining infrared rays after absorption are collected by the infrared receivers. The carbon dioxide concentration is calculated based on the intensity of the emitted infrared rays, the intensity of the remaining infrared rays, and the installation distance.

[0020] Preferably, the method for measuring the coalfield combustion volume includes:

[0021] The coalfield's top and side views were captured using an infrared camera. Based on the top and side views, an affine transformation was performed to obtain the coalfield's combustion volume.

[0022] Preferably, the method for obtaining the degree of coalfield combustion includes:

[0023] A combustion curve is constructed based on the combustion time and the first combustion data. The volume ratio of the experimental volume to the combustion volume is calculated. The second combustion data is scaled down proportionally based on the volume ratio. The scaled-down second combustion data is then substituted into the combustion curve to obtain the degree of coalfield combustion.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The coalfield fire zone detection method described in this invention involves collecting coal from the coalfield to simulate coalfield fire zone combustion, obtaining simulated combustion experimental data of the coal from combustion to completion, and then calculating the ratio between the volume of the coalfield fire zone and the volume of the collected coal. The data of the coalfield fire zone is then incorporated into the simulated combustion experimental data to obtain the degree of coalfield combustion, which is beneficial for the next step of coalfield fire zone management. Attached Figure Description

[0026] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a flowchart of the coalfield fire zone detection method according to an embodiment of the present invention. Detailed Implementation

[0028] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0030] Example 1

[0031] like Figure 1 As shown, this invention proposes a method for detecting coalfield fire zones, comprising the following steps:

[0032] Unburned coal was collected from the coalfield, and the volume of the collected coal was calculated to obtain the experimental volume;

[0033] Coal was placed into the experimental device to simulate combustion in a coalfield fire zone, and initial combustion data was collected.

[0034] Measure the volume of coalfield combustion and secondary combustion data;

[0035] The degree of coalfield combustion was obtained by using the first combustion data, the second combustion data, the experimental volume, and the combustion volume.

[0036] Further optimization of the scheme, methods for collecting unburned coal include:

[0037] When collecting unburned coal, first measure the depth of the coalfield. If it is an unmined coalfield, collect directly from the hole drilled when measuring the depth. If it is a mined coalfield, collect directly from the mine tunnel. Then, collect coal from the upper, middle and lower parts of the coal seam according to the location. Then, collect from the four directions of the coalfield fire zone. When collecting, it is necessary to collect coal that has not been affected by the fire zone.

[0038] Further optimization of the scheme, the methods for collecting the first combustion data include:

[0039] After the coal is heated, the gas inside the experimental apparatus is collected using a gas collection device, and the gas content is determined experimentally. At the same time, the density change of the coal during the experiment is measured using a radar device.

[0040] Further optimization of the scheme, including methods for experimentally determining gas content, includes:

[0041] Since sulfur dioxide absorbs light most strongly in the 280–300 nm range, ultraviolet absorption is used to monitor sulfur dioxide concentration.

[0042] Since carbon dioxide has an absorption peak in the 4.3µm region, and oxygen, nitrogen, carbon monoxide, and water vapor do not show significant absorption at this wavelength, infrared absorption is the best method to monitor carbon dioxide concentration.

[0043] Since coal combustion produces a large amount of dust, and dust has a significant impact on both methods, an electrostatic generator needs to be placed at the inlet of the collection device to remove the dust.

[0044] To further optimize the procedure, the measuring device needs to be calibrated before testing. First, zero gas is introduced, and the initial zero point value is recorded. Then, low-concentration and high-concentration standard gases are introduced separately, alternating between the zero gas and each standard gas, repeating this process three times and taking the average value. The linearity error of the analyzer must be checked. The sampling and analysis system should not be adjusted unless the calibration gas flow rate is not at the normal value. The relative error between the instrument's measured value and the standard gas reference value should not exceed ±5%. If the analyzer's linearity error exceeds ±5%, the cause must be investigated, and recalibration and checks must be performed until the requirements are met.

[0045] Further optimization of the scheme, including methods for monitoring sulfur dioxide concentration using ultraviolet absorption, includes:

[0046] Ultraviolet (UV) emission and reception devices are installed at both ends of the gas collection device, and the installation distance of the UV emission and reception devices is measured. After the UV emission device emits UV light, it is absorbed by sulfur dioxide, and the remaining UV light after absorption is collected by the UV reception device. The concentration of sulfur dioxide is calculated based on the intensity of the emitted UV light, the intensity of the remaining UV light, and the installation distance.

[0047] Further optimization of the scheme, including methods for monitoring carbon dioxide concentration using infrared absorption, includes:

[0048] Infrared transmitters and receivers are installed at both ends of the gas collection device, and the installation distance between the infrared transmitters and receivers is measured. The infrared rays emitted by the infrared transmitters are absorbed by carbon dioxide, and the remaining infrared rays after absorption are collected by the infrared receivers. The carbon dioxide concentration is calculated based on the intensity of the emitted infrared rays, the intensity of the remaining infrared rays, and the installation distance.

[0049] Further optimization of the scheme reveals that differences in radar wave frequency can reflect differences in coal density before and after combustion. The radar device includes an antenna, transmitter and receiver, signal processor, and terminal equipment. The transmitter is a radio frequency device that generates waveforms, which are transmitted to the antenna via a transceiver switch. The electromagnetic pulse is then emitted by the antenna, and the signal travels through the air to the detection area. The antennas, namely the transmitting and receiving antennas, require good directivity, low power loss, and stable transmission performance. Depending on the radar's detection application, antennas are available in 50MHz, 100MHz, 300MHz, 500MHz, and 1GHz frequencies. The receiver's main function is to extract and amplify weak reflected signals before transmitting them to the signal processor. The terminal equipment displays the acquired signals, including a waveform display showing the carrier waveform of the measurement results. The carrier waveform reflects the change in coal density before and after combustion.

[0050] Further optimization of the scheme, methods for measuring coalfield combustion volume include:

[0051] The coalfield's top and side views were captured using an infrared camera. Based on the top and side views, an affine transformation was performed to obtain the coalfield's combustion volume.

[0052] The specific method is as follows: obtain three-dimensional spatial data information through coalfield fire zone images; construct a triangular grid model of the coalfield based on the obtained three-dimensional spatial point cloud data information; perform an affine transformation on the triangular grid model to translate the center of the triangular grid model to the origin of the coordinate system; calculate the algebraic sum of the volumes of all the triangles in the triangular grid model after the affine transformation and the tetrahedron formed by the origin of the coordinate system, and the algebraic sum is the volume of the coalfield.

[0053] Further optimization of the scheme, methods for obtaining the degree of coalfield combustion include:

[0054] A combustion curve is constructed based on the combustion time and the first combustion data. The volume ratio of the experimental volume to the combustion volume is calculated. The second combustion data is scaled down proportionally based on the volume ratio. The scaled-down second combustion data is then substituted into the combustion curve to obtain the degree of coalfield combustion.

[0055] The second combustion data was collected using the same method as the first combustion data. It could be collected by using a drone equipped with the device, and the collected data was transmitted back to the laboratory wirelessly.

[0056] The combustion curve contains three curves: the sulfur dioxide change curve, the carbon dioxide change curve, and the density change curve. After the second combustion data is scaled down, three time points can be obtained. The average of the three time points is used as the standard time point, and the degree of coalfield combustion can be determined by the time points.

[0057] In summary, the significant advantages of this invention compared to existing technologies are summarized as follows:

[0058] 1) This invention can determine the concentration of major emitted gases using ultraviolet absorption and infrared absorption methods;

[0059] 2) This invention can calculate the volume of the fire zone in a coal yard by constructing a model and then performing an affine transformation.

[0060] 3) This invention calculates the ratio between the volume of the coalfield fire zone and the volume of collected coal, and then inputs the data of the coalfield fire zone into the simulated combustion experiment data to obtain the degree of coalfield combustion, which is beneficial for the next step of coalfield fire zone management.

[0061] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method of detecting a coalfield fire zone, characterized by, The method comprises the following steps: Collecting unburned coal from a coalfield and calculating the volume of the collected coal to obtain an experimental volume; Placing the coal into an experimental device to simulate the combustion of the coalfield fire zone and collecting first combustion data; The method of collecting first combustion data comprises: After starting to heat the coal, collecting the gas in the experimental device through a gas collection device and determining the gas content through an experiment; simultaneously, measuring the density change of the coal during the experiment through a radar device; The method of determining the gas content through an experiment comprises: Monitoring the sulfur dioxide concentration through ultraviolet absorption; Monitoring the carbon dioxide concentration through infrared absorption; Measuring the coalfield combustion volume and second combustion data; Obtaining the coalfield combustion degree from the first combustion data, the second combustion data, the experimental volume and the combustion volume; The method of obtaining the coalfield combustion degree comprises: Constructing a combustion curve graph according to the combustion time and the first combustion data, calculating the volume ratio of the experimental volume and the combustion volume, proportionally reducing the second combustion data according to the volume ratio, and bringing the reduced second combustion data into the combustion curve graph to obtain the coalfield combustion degree.

2. The coalfield fire area detection method according to claim 1, characterized in that, The method of collecting unburned coal comprises: Measuring the depth of the coalfield, and then collecting coal from three parts of the coal seam in four directions of the coalfield fire zone, and the coal collected should not be affected by the fire zone.

3. The coalfield fire zone detection method of claim 1, wherein, The method of monitoring the sulfur dioxide concentration through ultraviolet absorption comprises: Installing ultraviolet emission and receiving devices at both ends of the gas collection device, measuring the installation distance of the ultraviolet emission and receiving devices, collecting the remaining ultraviolet rays after the ultraviolet rays emitted by the ultraviolet emission device are absorbed by sulfur dioxide through the ultraviolet receiving device, and calculating the sulfur dioxide concentration according to the intensity of the emitted ultraviolet rays, the intensity of the remaining ultraviolet rays and the installation distance.

4. The coalfield fire zone detection method of claim 1, wherein, The method of monitoring the carbon dioxide concentration through infrared absorption comprises: Installing infrared emission and receiving devices at both ends of the gas collection device, measuring the installation distance of the infrared emission and receiving devices, collecting the remaining infrared rays after the infrared rays emitted by the infrared emission device are absorbed by carbon dioxide through the infrared receiving device, and calculating the carbon dioxide concentration according to the intensity of the emitted infrared rays, the intensity of the remaining infrared rays and the installation distance.

5. The coalfield fire zone detection method of claim 1, wherein, The method of measuring the coalfield combustion volume comprises: Taking a top view and a front view of the coalfield by using an infrared camera, performing affine transformation according to the top view and the side view, and obtaining the coalfield combustion volume.

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