Coal dust influence suppression method for coal mine gas laser detection and detection device

Abstract

The invention discloses a coal dust influence suppression method for coal mine gas laser detection and a detection device, and the method comprises the steps: extracting gas in a coal mine goaf through a gas pump and a beam tube of the coal mine gas laser detection device, and detecting a characteristic absorption spectrum of the gas in the goaf by adopting a TDLAS technology; correcting a second harmonic signal and a peak value in the characteristic absorption spectrum by considering the attenuation influence of the coal dust in the goaf gas on the second harmonic signal of the laser penetrating through the goaf gas; and obtaining the accurate concentration value of each component gas in the goaf gas by using the corrected second harmonic signal peak value. According to the invention, the influence of coal dust on gas concentration detection can be greatly reduced, the sensitivity of gas detection is improved, and good detection effect and precision can be achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal mine monitoring and surveillance, and relates to a method and a detection device for suppressing the influence of coal dust on coal mine gas laser detection. Background Art

[0002] The traditional ground-type bundle pipe monitoring system has both the air pump and the detection equipment placed on the ground, and the gas in the goaf is transmitted to the ground through a pipeline of no less than 10 km. Due to the long pipeline, it has a large air extraction resistance and requires a high-power air pump. There are many pipe joints and it is easy to leak. The ground pipeline is prone to ice and blockage in winter. The gas is generally analyzed by a chromatograph, which has a long analysis cycle and complex maintenance. At present, the underground mine spontaneous combustion gas bundle pipe monitoring system has begun to be gradually applied. The gas analysis equipment, gas path control equipment, sampling pump, power box, switch and other equipment that make up the system are all installed in the underground chamber, which effectively solves the problem of long sampling distance and shortens the sampling distance of the monitoring system to less than 2 km. However, the strategy accuracy and reliability of the gas concentration parameters of the existing underground mine spontaneous combustion gas bundle pipe monitoring system need to be further improved; there is a lack of pipeline fault diagnosis function; usually a flameproof vacuum pump or a water circulation pump is used, the product cost is high and the equipment volume is large; the gas extraction time is very long due to the polling of a single pump.

[0003] When laser passes through a gas medium, absorption and scattering will occur. In a homogeneous medium, the scattered waves cancel each other out, absorption is the main effect, and the light propagates in the original direction; in an inhomogeneous medium, light is absorbed and scattered at the same time, and the scattered waves are superimposed on each other, changing the propagation direction of the light. When the laser passes through a gas containing dust, the dust will absorb and scatter the laser, resulting in gas concentration detection errors due to laser intensity attenuation. A large amount of coal dust is generated during coal mining. When the traditional ground gas laser detection scheme uses TDLAS technology to measure gas concentration, because there is not much dust in the ground environment, the effect of dust on laser detection is generally ignored. This laser gas detection technology will cause relatively large errors when applied to coal mines. Therefore, in order to improve the gas detection accuracy of coal mine goafs, it is necessary to design a set of coal mine gas laser detection coal dust influence suppression methods to eliminate the influence of coal mine dust on laser gas detection accuracy. Summary of the invention

[0004] In order to solve the deficiencies in the prior art, the present invention provides a method and a detection device for suppressing the influence of coal dust on coal mine gas laser detection, thereby eliminating the influence of coal mine dust on the accuracy of laser gas detection and reducing the error of laser detection of gas in coal mine goaf.

[0005] The present invention adopts the following technical solution.

[0006] A first aspect of the present invention provides a method for suppressing the influence of coal dust on coal mine gas laser detection, comprising:

[0007] The gas in the coal mine goaf is extracted through the gas pump and beam tube of the coal mine gas laser detection device, and the characteristic absorption spectrum of the gas in the goaf is detected by TDLAS technology.

[0008] Considering the attenuation effect of coal dust in the gas of the goaf on the second harmonic signal of the laser passing through it, the peak value of the second harmonic signal in the characteristic absorption spectrum is corrected;

[0009] The corrected second harmonic signal peak value is used to obtain the accurate concentration value of each component gas in the goaf gas.

[0010] Preferably, the method of taking into account the attenuation effect of coal dust in the goaf gas on the second harmonic signal of the laser passing therethrough and correcting the peak value of the second harmonic signal in the characteristic absorption spectrum comprises:

[0011] The output light intensity slope is used to correct the peak value of the second harmonic signal in the characteristic absorption spectrum to eliminate the attenuation effect of coal dust in the goaf gas on the second harmonic signal of the laser passing therethrough.

[0012] Preferably, the peak value of the second harmonic signal in the characteristic absorption spectrum is corrected by using the slope of the emitted light intensity, and the formula is as follows:

[0013]

[0014] Where P2′ f-0 is the peak value of the second harmonic signal before correction;

[0015] P2″ f-0 is the peak value of the second harmonic signal after correction;

[0016] k′ t It is the slope of the outgoing light intensity when coal dust exists in the gas in the goaf.

[0017] Preferably, the slope k′ of the emitted light intensity when coal dust exists in the goaf gas is t The calculation formula is:

[0018]

[0019] Among them, I t ′(T saw ), I t ′(0) is respectively the time t is T saw and the laser emission intensity at time 0;

[0020] T saw is the scanning period of the sawtooth wave signal.

[0021] Preferably, the corrected second harmonic signal peak value is used to obtain the accurate concentration value of each component gas in the goaf gas, and the formula is as follows:

[0022]

[0023] Where P2″ f-0 is the peak value of the second harmonic signal after correction;

[0024] C is the gas concentration of the component to be measured in the goaf gas;

[0025] k t is the slope of the outgoing light intensity when there is no coal dust in the gas in the goaf;

[0026] P is pressure;

[0027] S(T) is the intensity of the gas absorption line of the component to be measured in the gas of the goaf;

[0028] L is the effective optical path of the laser in the gas of the goaf;

[0029] Δv c is the half-height and half-width of the Lorentz line shape;

[0030] is the average light intensity scanned by the laser;

[0031] S0(0,m), S2(0,m), and S4(0,m) are all functions of the normalized center frequency detuning amount 0 and the modulation depth m;

[0032] ΔI2 is the linear and nonlinear light intensity modulation amplitude;

[0033] is the phase difference between nonlinear light intensity modulation and frequency modulation.

[0034] Preferably, the method further comprises: performing a spontaneous combustion fire early warning analysis in the goaf of the coal mine according to the concentration of each component gas measured by the laser sensor module and the ambient temperature of the goaf measured by the distributed optical fiber temperature measurement system of the goaf through the optical fiber, as follows:

[0035] If A′(x,y)×B′(x,y)×C′(x,y)×D′(x,y)×E′(x,y)×G′(x,y)+F′(x,y)×H′(x,y)×I′(x,y)≥1, the goaf location (x,y) is a spontaneous combustion fire hazard zone, and a spontaneous combustion fire warning is issued;

[0036] Where A′(x,y) is the ambient temperature change rate index at the goaf location (x,y);

[0037] B′(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0038] C′(x,y) is the oxygen concentration index at the goaf location (x,y);

[0039] D′(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0040] E′(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0041] F′(x,y) is the acetylene concentration index at the goaf location (x,y);

[0042] G′(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0043] H′(x,y) is the ammonia concentration index at the goaf location (x,y);

[0044] I′(x,y) is the hydrogen sulfide concentration index at the goaf location (x,y).

[0045] Preferably, the value of each indicator is as follows:

[0046]

[0047] Where A(x,y) is the rate of change of ambient temperature at the goaf location (x,y);

[0048] d means one day;

[0049] B(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0050] C(x,y) is the oxygen concentration at the goaf location (x,y);

[0051] D(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0052] E(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0053] F(x,y) is the acetylene concentration at the goaf location (x,y);

[0054] G(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0055] H(x,y) is the ammonia concentration at the goaf location (x,y);

[0056] I(x,y) is the hydrogen sulfide concentration at the goaf location (x,y).

[0057] The second aspect of the present invention provides a coal mine gas laser detection device, comprising a monitoring host, a gas extraction and water filtration control box, a power supply box, a network interface and a host computer; wherein the monitoring host, the gas extraction and water filtration control box and the power supply box are arranged in an underground electromechanical chamber; the host computer is arranged above the well and communicates with the monitoring host through a network interface;

[0058] The monitoring host is powered by a power supply box and is used for on-site detection, display, and over-limit warning of the flow rate of the beam tube gas, the concentration of multiple gases to be measured in the goaf, and the temperature, as well as remote communication with the host computer, and controls the gas extraction and water filtration of the gas extraction and water filtration control box, wherein the concentration of multiple gases to be measured in the goaf is detected based on the coal mine gas laser detection coal dust influence suppression method described in any one of claims 1 to 5;

[0059] The air extraction and water filtration control box is powered by the power box and is used for extraction, water filtration and flow measurement of the gas from the 8-way bundle pipes. The extracted and water-filtered gas is transported to the monitoring host through the air pipe. Each bundle pipe is equipped with a micro air pump to extract the gas from the 8-way bundle pipes synchronously.

[0060] The host computer is used for data collection and display from multiple monitoring hosts, early warning of spontaneous combustion of coal mines, and remote control.

[0061] Preferably, the monitoring host adopts a laser gas detection module and utilizes the coal mine gas laser detection coal dust influence suppression method to detect the concentrations of nine gas components, namely, carbon dioxide, oxygen, acetylene, methane, ethylene, carbon monoxide, ethane, ammonia, and hydrogen sulfide, in the beam tube gas;

[0062] The host computer performs early warning analysis of spontaneous combustion fire in the goaf of the coal mine based on the concentrations of the nine gas components measured by the laser sensor module and the goaf temperature measured by the goaf distributed optical fiber temperature measurement system through optical fiber.

[0063] Preferably, one monitoring host is connected to at most two control boxes to detect at most 16 beam tube gases.

[0064] Preferably, the monitoring host accesses the nearby network interface through optical fiber underground, uploads data to the host computer through Ethernet, and receives commands from the host computer; communicates with the air extraction and water filtration control box through RS485, and sends the start and stop control commands of the sampling pump in the control box to the air extraction and water filtration control box.

[0065] Preferably, the micro air pump is a negative pressure suction intrinsically safe micro air pump.

[0066] Compared with the prior art, the beneficial effects of the present invention include at least:

[0067] The present invention utilizes the slope of the emitted light intensity to correct the second harmonic signal and removes the coal dust transmittance by calculation, thereby eliminating the influence of coal dust on gas concentration detection. It can greatly reduce the interference of coal dust on gas concentration detection, improve the sensitivity of gas detection, and achieve good detection effect and accuracy, providing a guarantee for the detection device to accurately analyze the sampled gas.

[0068] The present invention can effectively monitor and analyze the index gas components of the goaf (carbon dioxide, oxygen, acetylene, methane, ethylene, carbon monoxide, ethane, ammonia, hydrogen sulfide) in the underground spontaneous combustion fire gas accurately, without drift, calibration, maintenance, fast measurement speed, high accuracy and strong reliability. The device has the characteristics of advanced technology, continuous monitoring, multiple functions, convenient operation and fault diagnosis. If the gas content at the monitoring point exceeds the limit, an audible and visual alarm can be given on site, and the upper computer can realize the early warning and forecast of the spontaneous combustion fire in the coal mine, providing a new generation of solutions for the monitoring of spontaneous combustion fire in coal mines and escorting the safe production of coal mines.

[0069] The present invention also introduces dynamic evaluation indicators such as change rate and ratio based on multiple gas concentrations and temperatures to carry out coal spontaneous combustion fire warning in coal mine goafs, eliminates the influence of factors such as ventilation on single gas warning indicators, and solves the problem of large errors in single indicator and static parameter evaluation, so that it can more reasonably reflect the risk of spontaneous combustion in goafs, improves the precision and accuracy of prediction, and enables the system to identify fire risks at an early stage, prevent and control spontaneous combustion of coal in goafs at an early stage, ensure safe production in coal mines, and reduce casualties and property losses.

[0070] The coal mine gas laser detection device of the present invention adopts laser detection technology to realize full laser real-time online detection of 9 gas concentrations, realizes accurate and reliable measurement of gas concentration parameters, and has the following characteristics:

[0071] Full laser detection of 9 types of gases improves detection accuracy and is calibration-free for 6 months, reducing maintenance workload.

[0072] Realizing underground distributed layout shortens pipeline distance and reduces the risk of blockage and gas leakage.

[0073] It has pipeline fault diagnosis function, can automatically remind when leakage and blockage occur, and can perform back-blowing operation through air pump to blow through the pipeline.

[0074] It adopts the design of intrinsically safe micro air pump, negative pressure exhaust type, local and remote control of air pump start and stop, and multiple air pumps working in parallel, which greatly shortens the exhaust time. The air pump has a long service life, high efficiency and reliable operation, breaking the conventional mode of flameproof vacuum pump or water circulation pump, greatly reducing product cost and power consumption, and reducing the size of the equipment.

[0075] One tube bundle is designed to be connected to one micro air pump for gas extraction. Eight tube bundles share eight micro air pumps. The eight pumps are controlled by the host and can perform gas extraction at the same time, which shortens the gas extraction time and solves the problem of very long gas extraction time caused by conventional single pump polling gas extraction.

[0076] By adopting the above-ground monitoring method, on-site monitoring of multiple gases in the goaf can be realized, which can be integrated with the distributed optical fiber temperature measurement system in the goaf for monitoring and analysis, thus improving the accuracy and precision of monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0077] Figure 1 This is a flow chart of the method for suppressing the influence of coal dust on coal mine gas laser detection according to the present invention;

[0078] Figure 2 This is a structural diagram of the coal mine gas laser detection device of the present invention;

[0079] Figure 3 This is a schematic diagram of the effect of coal dust on the second harmonic signal;

[0080] Figure 4 It is the corrected second harmonic signal when the coal dust transmittance is 1 and 0.5. DETAILED DESCRIPTION

[0081] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0082] Embodiment 1 of the present invention provides a method for suppressing the influence of coal dust on coal mine gas laser detection, such as Figure 1 As shown, including:

[0083] The gas in the coal mine goaf is extracted through the gas pump and beam tube of the coal mine gas laser detection device, and the characteristic absorption spectrum of the gas in the goaf is detected by TDLAS technology.

[0084] Considering the attenuation effect of coal dust in the gas of the goaf on the second harmonic signal of the laser passing through it, the second harmonic signal and peak value in the characteristic absorption spectrum are corrected;

[0085] The corrected second harmonic signal peak value is used to obtain the accurate concentration value of each component gas in the goaf gas.

[0086] Further preferably, based on the tunable laser spectral absorption technology TDLAS, the slope of the emitted light intensity is used to correct the second harmonic signal, and the coal dust transmittance is removed by calculation, thereby eliminating the influence of coal dust on gas concentration detection. The specific analysis is as follows:

[0087] In order to improve the concentration detection accuracy, the present invention proposes a method for correcting the second harmonic signal to eliminate the influence of coal dust on the measurement result.

[0088] Coal dust reduces both the outgoing light intensity and the second harmonic signal, and the degree of reduction is related to the transmittance T of the coal dust. r Therefore, it is proposed to use the characteristics of the outgoing light intensity signal to correct the second harmonic signal, thereby eliminating the influence of coal dust on gas concentration measurement.

[0089] The TDLAS laser detection driving current signal used in the present invention is in the form of a superposition of a low-frequency sawtooth wave and a high-frequency sine wave. In view of the modulation characteristics of the laser, the initial laser light intensity is also in the form of a superposition of two waves, and its expression is:

[0090]

[0091] Where I0 is the center intensity of the laser;

[0092] I saw is the sweep amplitude of the sawtooth signal;

[0093] The light intensity scanning range is (I0-I saw , I0+I saw );

[0094] T saw is the scanning period of the sawtooth wave signal;

[0095] ω is the angular frequency of the modulation signal;

[0096] ΔI1 and ΔI2 are the linear and nonlinear light intensity modulation amplitudes, respectively;

[0097] and are the phase differences between linear and nonlinear light intensity modulation and frequency modulation, respectively.

[0098] Since the period of the sawtooth wave signal is generally an integer multiple of the period of the sine wave signal, Therefore, the slope k0 of the incident light intensity in one scanning cycle can be expressed as:

[0099]

[0100] It can be seen from the above formula that the slope of the incident light intensity is the slope of the sawtooth wave part.

[0101] After the laser passes through the gas to be measured, the expression of the outgoing light intensity signal is as follows:

[0102]

[0103] In the formula, is the average light intensity scanned by the laser;

[0104] P is pressure;

[0105] S(T) is the intensity of the absorption line of the gas being measured;

[0106] g[v(t)] is the linear function of the measured gas;

[0107] C is the concentration of the gas being measured;

[0108] L is the effective optical path of the laser in the gas being measured.

[0109] The expression of the outgoing light intensity signal without coal dust is:

[0110]

[0111] It can be seen from the above formula that the outgoing light intensity signal is also a superposition of a sawtooth wave and a sine wave. Due to the absorption of the gas, an absorption peak is generated at the center of the outgoing light intensity signal. saw When g[v(t)] approaches 0, exp(-PS(T)g[v(t)]CL)→1, and there is no absorption on both sides. Therefore, the slope k of the output light intensity is t It can be expressed as:

[0112]

[0113] It can be seen that when coal dust is not included, the slope of the outgoing light intensity is consistent with the slope of the incident light intensity sawtooth wave.

[0114] When the laser passes through coal dust, the outgoing light intensity and the incident light intensity also satisfy the Lambert-Beer law, expressed as follows:

[0115] I t =I0exp(-K ext L) (6)

[0116] In the formula, K ext is the extinction coefficient of coal dust.

[0117] Therefore, the transmittance of coal dust is T r It can be expressed as:

[0118]

[0119] When measuring gas, the laser is affected by both gas and coal dust. Adding the coal dust transmittance to the output light intensity expression (3), the final laser output light intensity can be expressed as:

[0120]

[0121] When coal dust is included, the expression of the outgoing light intensity is:

[0122]

[0123] Similarly, its slope can be expressed as:

[0124]

[0125] From the above formula, we can see that when coal dust exists, the slope k' of the outgoing light intensity is t That is k t With T r The product of T, the slope of the outgoing light intensity signal and the amplitude of the second harmonic signal are all related to T r It is proportional to the output light intensity, so the slope of the output light intensity can be used to correct the second harmonic signal.

[0126] The v(t) function in formula (3) can be expressed as:

[0127]

[0128] In the formula, is the average frequency of the laser scan, v m is the amplitude of the frequency modulation.

[0129] Then, formula (3) can be expressed as:

[0130]

[0131] It can be expanded into a Fourier cosine order function, and formula (12) can be expressed as:

[0132]

[0133] In the formula, is the Fourier expansion coefficient, abbreviated as H n , the expression is:

[0134]

[0135] Expanding formula (13), we get the outgoing light intensity with a frequency of 2ω as:

[0136]

[0137] Where H0, H1, H2, H3, and H4 are Fourier expansion coefficients.

[0138] Decomposing formula (15), we can obtain the X component as:

[0139]

[0140] When the concentration is 0, the background signal of the X component is:

[0141]

[0142] When the concentration is not 0, the expression for removing the background signal of the X component is:

[0143]

[0144] The normalized center frequency detuning expression is as follows:

[0145]

[0146] In the formula, Δv c is the half-height and half-width of the Lorentz line shape.

[0147] The modulation depth expression is:

[0148]

[0149] The function of H is:

[0150]

[0151] In the formula, S n (x,m) is a function of x and m.

[0152] At the center frequency of the gas absorption line, that is, when x = 0, S1(0,m) = S3(0,m) = 0,

[0153] S2(0,m) and S4(0,m) have maximum values.

[0154] When x=0, X 2f-0 The value of is the peak value, then:

[0155]

[0156] Using the same calculation method as above, formula (8) is expanded to obtain the outgoing light intensity with a frequency of 2ω when coal dust is included:

[0157]

[0158] Decomposing formula (23), we can obtain the X component as:

[0159]

[0160] The peak expression after removing the background signal is:

[0161]

[0162] Dividing formula (24) by the slope expression (10) of the output light intensity, the corrected second harmonic signal expression is obtained as follows:

[0163]

[0164] Dividing formula (25) by the slope expression (10) of the output light intensity, the corrected second harmonic peak expression is as follows:

[0165]

[0166] The above formulas (26) and (27) use the slope of the output light intensity to correct the second harmonic signal and the peak value, and remove the coal dust transmittance through calculation, thereby eliminating the influence of coal dust on gas concentration detection.

[0167] The present invention uses the corrected second harmonic peak to perform concentration inversion, and the concentration inversion formula obtained according to formula (27) is as follows:

[0168]

[0169] It can be seen from the above formula that when other conditions are the same, the concentration C and the second harmonic peak value P2″ after the slope correction of the output light intensity are f-0 (Right now ) is in a linear relationship, and there is no coal dust transmittance parameter in the expression. The concentration value obtained by the expression is not affected by coal dust and has a high calculation accuracy.

[0170] Further preferably, the method of the present invention further comprises: performing a spontaneous combustion fire early warning analysis of the coal mine goaf according to the concentration of each component gas measured by the laser sensor module and the goaf ambient temperature measured by the goaf distributed optical fiber temperature measurement system through optical fiber, as follows:

[0171] If A′(x,y)×B′(x,y)×C′(x,y)×D′(x,y)×E′(x,y)×G′(x,y)+F′(x,y)×H′(x,y)×I′(x,y)≥1, the goaf location (x,y) is a spontaneous combustion fire hazard zone, and a spontaneous combustion fire warning is issued;

[0172] Where A′(x,y) is the ambient temperature change rate index at the goaf location (x,y);

[0173] B′(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0174] C′(x,y) is the oxygen concentration index at the goaf location (x,y);

[0175] D′(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0176] E′(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0177] F′(x,y) is the acetylene concentration index at the goaf location (x,y);

[0178] G′(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0179] H′(x,y) is the ammonia concentration index at the goaf location (x,y);

[0180] I′(x,y) is the hydrogen sulfide concentration index at the goaf location (x,y).

[0181] The values ​​of each indicator are as follows:

[0182]

[0183] Where A(x,y) is the rate of change of ambient temperature at the goaf location (x,y);

[0184] B(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0185] C(x,y) is the oxygen concentration at the goaf location (x,y);

[0186] D(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0187] E(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0188] F(x,y) is the acetylene concentration at the goaf location (x,y);

[0189] G(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0190] H(x,y) is the ammonia concentration at the goaf location (x,y);

[0191] I(x,y) is the hydrogen sulfide concentration at the goaf location (x,y).

[0192] Embodiment 2 of the present invention provides a coal mine gas laser detection device, such as Figure 2 As shown, it includes a monitoring host, an air extraction and water filtration control box, a power box, a network interface and a host computer; wherein the monitoring host, the air extraction and water filtration control box and the power box are arranged in the goaf of the underground coal mine; the host computer is arranged above the well and communicates with the monitoring host through the network interface;

[0193] The monitoring host is powered by a power box and is used for on-site detection, display, and over-limit warning of the flow rate of the beam tube gas, the concentration of multiple gases to be measured, and the temperature, as well as remote communication with the host computer, and controls the gas extraction and water filtration of the gas extraction and water filtration control box. The concentrations of multiple gases to be measured are detected based on the above-mentioned coal mine gas laser detection coal dust influence suppression method;

[0194] Further preferably, the monitoring host is mainly composed of a housing, a liquid crystal display, a flow sensor, a temperature sensor, a solenoid valve, a water filter, a main control board and 9 laser gas detection modules (carbon dioxide, oxygen, acetylene, methane, ethylene, carbon monoxide, ethane, ammonia, hydrogen sulfide). It is powered by a power box to realize manual and automatic detection of 9 gases, flow and temperature detection of pipeline gas, local control function through infrared remote control, remote control function through host computer, and local display of detection data and working status through liquid crystal display.

[0195] The monitoring host uses a laser gas detection module (laser sensor module), utilizes the coal mine gas laser detection coal dust influence suppression method, and adopts tunable laser spectral absorption technology TDLAS to detect the concentration of 9 gases to be tested, including carbon dioxide, oxygen, acetylene, methane ethylene, carbon monoxide, ethane, ammonia, and hydrogen sulfide, to achieve the analysis and measurement of the hazardous gas components in the gases to be tested at the corresponding monitoring points in the goaf of underground coal mines, and upload the measurement results in real time to provide early warning for spontaneous combustion of coal mines. Specifically, the host computer can be used for early warning, and the monitoring host can be used to realize the on-site over-limit alarm of the hazardous gas concentration.

[0196] Further preferably, the temperature sensor in the monitoring host tests the temperature of the drawn gas to determine whether the gas in the pipeline is burning. Because the temperature of the gas will drop after passing through a long pipeline, it is not the actual temperature in the goaf. In this regard, the laser sensing module is integrated with the goaf distributed optical fiber temperature measurement system for monitoring and analysis, wherein the goaf distributed optical fiber temperature measurement system directly places the optical fiber into the goaf and directly measures the temperature in the goaf, which can truly reflect whether a fire has occurred in the goaf.

[0197] The laser sensor module measures the concentration of nine gases, and the distributed optical fiber temperature measurement system in the goaf measures the temperature of the goaf through optical fiber. When the upper computer performs fire warning analysis in the goaf, it can conduct a comprehensive analysis of the two types of data to improve the accuracy of the warning.

[0198] The monitoring host is connected to the nearby network interface through optical fiber underground, uploads data to the host computer through Ethernet, and receives commands from the host computer; communicates with the air extraction and water filtration control box through RS485, and sends the start and stop control commands of the sampling pump in the control box to the air extraction and water filtration control box.

[0199] The micro air pump is a negative pressure suction type intrinsically safe micro air pump.

[0200] The air extraction and water filtration control box is powered by the power box and is used for extraction, water filtration and flow measurement of the gas from the 8-way bundle pipes. The extracted and water-filtered gas is transported to the monitoring host through the air pipe. Each bundle pipe is equipped with a micro air pump to extract the gas from the 8-way bundle pipes synchronously.

[0201] Further preferably, the air extraction and water filtration control box is mainly composed of a shell, a micro air pump, a solenoid valve, a water filter, a control panel, a bus and a float flowmeter. Power is supplied by a power supply box to realize the extraction of gas from 8-way bundle tubes, realize the water filtration of gas, measure the flow rate through a float flowmeter, transmit the extracted and filtered gas to the monitoring host through a pipeline, and communicate with the monitoring host through an RS485 communication line. One bundle tube is connected by a micro air pump for gas extraction, and 8-way bundle tubes share 8 micro air pumps. The 8 pumps are controlled by the host and can perform air extraction at the same time, which shortens the air extraction time and solves the problem of very long air extraction time caused by conventional single pump polling air extraction. In addition, the present invention adopts the design of an intrinsically safe micro air pump, breaking the conventional explosion-proof vacuum pump or water circulation pump mode, greatly reducing product costs and reducing equipment size.

[0202] The host computer is used for data collection, display and remote control of multiple monitoring hosts, realizing data collection and display of multiple monitoring hosts and remote control of the hosts.

[0203] Each air extraction and water filtration control box is connected to an 8-channel bundle pipe to extract gases from 8 bundle pipes. The power supply is provided by a power supply box. The air extraction and water filtration control box transmits the extracted and filtered gas to the monitoring host through the air pipe, and the monitoring host detects 9 kinds of gases. The monitoring host is connected to the air extraction and water filtration control box via RS485 and sends the sampling pump start and stop control command to the control box. A monitoring host can be connected to up to 2 control boxes to detect up to 16 bundle pipe gases. The monitoring host is connected to the nearby network interface through optical fiber in the well, uploads data to the host computer through Ethernet, and receives commands from the host computer.

[0204] The monitoring host, air extraction and water filtration control box and power supply box are arranged underground and installed in the electromechanical chamber of the mining area. The upper computer is installed in the monitoring room above the well.

[0205] Figure 3The second harmonic signals with and without coal dust are given by Figure 3 It can be seen that when coal dust exists, the second harmonic signal is attenuated as a whole, the baseline is lowered, and the peak value of the second harmonic signal after removing the background signal is also attenuated.

[0206] The present invention does not contain coal dust (ie, the transmittance T r =1) and the coal dust transmittance is T r = 0.5 as an example. When the detected gas concentration is the same, the second harmonic signal after the slope correction of the emitted light intensity is as follows Figure 4 As shown. Figure 4 It can be seen that the second harmonic signal passing through the coal dust is not affected by the coal dust.

[0207] Through practical application tests, the present invention can greatly reduce the interference of coal dust on the detection of gas concentration in goaf areas, improve the sensitivity of gas detection, and achieve good detection effect and accuracy, providing a guarantee for the detection device to accurately analyze the sampled gas.

[0208] Embodiment 3 of the present invention provides a terminal, including a processor and a storage medium; the storage medium is used to store instructions; the processor is used to operate according to the instructions to execute the steps of the method.

[0209] Embodiment 4 of the present invention provides a computer-readable storage medium having a computer program stored thereon, which implements the steps of the method when executed by a processor.

[0210] Compared with the prior art, the beneficial effects of the present invention include at least:

[0211] The present invention utilizes the slope of the emitted light intensity to correct the second harmonic signal and removes the coal dust transmittance by calculation, thereby eliminating the influence of coal dust on gas concentration detection. It can greatly reduce the interference of coal dust on gas concentration detection, improve the sensitivity of gas detection, and achieve good detection effect and accuracy, providing a guarantee for the detection device to accurately analyze the sampled gas.

[0212] The present invention can effectively monitor and analyze the index gas components of the goaf (carbon dioxide, oxygen, acetylene, methane, ethylene, carbon monoxide, ethane, ammonia, hydrogen sulfide) in the underground spontaneous combustion fire gas accurately, without drift, calibration, maintenance, fast measurement speed, high accuracy and strong reliability. The device has the characteristics of advanced technology, continuous monitoring, multiple functions, convenient operation and fault diagnosis. If the gas content at the monitoring point exceeds the limit, an audible and visual alarm can be given on site, and the upper computer can realize the early warning and forecast of the spontaneous combustion fire in the coal mine, providing a new generation of solutions for the monitoring of spontaneous combustion fire in coal mines and escorting the safe production of coal mines.

[0213] The coal mine gas laser detection device of the present invention adopts laser detection technology to realize full laser real-time online detection of 9 gas concentrations, realizes accurate and reliable measurement of gas concentration parameters, and has the following characteristics:

[0214] Full laser detection of 9 types of gases improves detection accuracy and is calibration-free for 6 months, reducing maintenance workload.

[0215] Realizing underground distributed layout shortens pipeline distance and reduces the risk of blockage and gas leakage.

[0216] It has pipeline fault diagnosis function, can automatically remind when leakage and blockage occur, and can perform back-blowing operation through air pump to blow through the pipeline.

[0217] It adopts the design of intrinsically safe micro air pump, negative pressure exhaust type, local and remote control of air pump start and stop, and multiple air pumps working in parallel, which greatly shortens the exhaust time. The air pump has a long service life, high efficiency and reliable operation, breaking the conventional mode of flameproof vacuum pump or water circulation pump, greatly reducing product cost and power consumption, and reducing the size of the equipment.

[0218] One tube bundle is designed to be connected to one micro air pump for gas extraction. Eight tube bundles share eight micro air pumps. The eight pumps are controlled by the host and can perform gas extraction at the same time, which shortens the gas extraction time and solves the problem of very long gas extraction time caused by conventional single pump polling gas extraction.

[0219] By adopting the above-ground monitoring method, on-site monitoring of multiple gases in the goaf can be realized, which can be integrated with the distributed optical fiber temperature measurement system in the goaf for monitoring and analysis, thus improving the accuracy and precision of monitoring.

[0220] The host computer performs early warning analysis of spontaneous combustion fire in the goaf of coal mines based on the concentrations of the nine gas components measured by the laser sensor module and the goaf temperature measured by the goaf distributed optical fiber temperature measurement system through optical fiber. The early warning method for spontaneous combustion fire in the goaf is as follows:

[0221]

[0222] If A′(x,y)×B′(x,y)×C′(x,y)×D′(x,y)×E′(x,y)×G′(x,y)+F′(x,y)×H′(x,y)×I′(x,y)≥1, the goaf location (x,y) is a spontaneous combustion fire hazard zone, and the system sends a spontaneous combustion fire warning;

[0223] Where A′(x,y) is the ambient temperature change rate index at the goaf location (x,y);

[0224] B′(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0225] C′(x,y) is the oxygen concentration index at the goaf location (x,y);

[0226] D′(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0227] E′(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0228] F′(x,y) is the acetylene concentration index at the goaf location (x,y);

[0229] G′(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0230] H′(x,y) is the ammonia concentration index at the goaf location (x,y);

[0231] I′(x,y) is the hydrogen sulfide concentration index at the goaf location (x,y).

[0232] A(x,y) is the rate of change of ambient temperature at the goaf location (x,y);

[0233] B(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y);

[0234] C(x,y) is the oxygen concentration at the goaf location (x,y);

[0235] D(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y);

[0236] E(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y);

[0237] F(x,y) is the acetylene concentration at the goaf location (x,y);

[0238] G(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y);

[0239] H(x,y) is the ammonia concentration at the goaf location (x,y);

[0240] I(x,y) is the hydrogen sulfide concentration at the goaf location (x,y).

[0241] The present disclosure may be a system, a method and / or a computer program product. The computer program product may include a computer-readable storage medium carrying computer-readable program instructions for causing a processor to implement various aspects of the present disclosure.

[0242] A computer-readable storage medium may be a tangible device that can hold and store instructions used by an instruction execution device. A computer-readable storage medium may be, for example, but not limited to, an electrical storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. More specific examples of computer-readable storage media (a non-exhaustive list) include: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a static random access memory (SRAM), a portable compact disk read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanical encoding device, such as a punch card or a raised structure in a groove on which instructions are stored, and any suitable combination of the foregoing. As used herein, a computer-readable storage medium is not to be interpreted as a transient signal per se, such as a radio wave or other freely propagating electromagnetic wave, an electromagnetic wave propagating through a waveguide or other transmission medium (e.g., a light pulse through a fiber optic cable), or an electrical signal transmitted through a wire.

[0243] The computer-readable program instructions described herein can be downloaded from a computer-readable storage medium to each computing / processing device, or downloaded to an external computer or external storage device via a network, such as the Internet, a local area network, a wide area network, and / or a wireless network. The network can include copper transmission cables, optical fiber transmissions, wireless transmissions, routers, firewalls, switches, gateway computers, and / or edge servers. The network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards the computer-readable program instructions for storage in the computer-readable storage medium in each computing / processing device.

[0244] The computer program instructions for performing the operation of the present disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-related instructions, microcode, firmware instructions, state setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages, such as Smalltalk, C++, etc., and conventional procedural programming languages, such as "C" language or similar programming languages. Computer-readable program instructions may be executed completely on a user's computer, partially on a user's computer, as an independent software package, partially on a user's computer, partially on a remote computer, or completely on a remote computer or server. In the case of a remote computer, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or may be connected to an external computer (e.g., using an Internet service provider to connect via the Internet). In some embodiments, an electronic circuit, such as a programmable logic circuit, a field programmable gate array (FPGA), or a programmable logic array (PLA), may be customized by utilizing the state information of the computer-readable program instructions, and the electronic circuit may execute the computer-readable program instructions, thereby realizing various aspects of the present disclosure.

[0245] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for suppressing the influence of coal dust on coal mine gas laser detection, characterized in that: include: The gas in the coal mine goaf is extracted through the gas pump and beam tube of the coal mine gas laser detection device, and the characteristic absorption spectrum of the gas in the goaf is detected by TDLAS technology. Considering the attenuation effect of coal dust in the gas of the goaf on the second harmonic signal of the laser passing through it, the peak value of the second harmonic signal in the characteristic absorption spectrum is corrected; The corrected second harmonic signal peak value is used to obtain the accurate concentration value of each component gas in the goaf gas.

2. A method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 1, characterized in that: The method of taking into account the attenuation effect of coal dust in the gas in the goaf on the second harmonic signal of the laser passing therethrough and correcting the peak value of the second harmonic signal in the characteristic absorption spectrum comprises: The output light intensity slope is used to correct the peak value of the second harmonic signal in the characteristic absorption spectrum to eliminate the attenuation effect of coal dust in the goaf gas on the second harmonic signal of the laser passing therethrough.

3. A method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 2, characterized in that: The second harmonic signal peak in the characteristic absorption spectrum is corrected by using the slope of the emitted light intensity, and the formula is as follows: Where P2′ f-0 is the peak value of the second harmonic signal before correction; P2″ f-0 is the peak value of the second harmonic signal after correction; k′ t It is the slope of the outgoing light intensity when coal dust exists in the gas in the goaf.

4. A method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 3, characterized in that: The slope k' of the outgoing light intensity when coal dust exists in the gas of the goaf t The calculation formula is: Among them, I t ′(T saw ), I t ′(0) is respectively the time t is T saw and the laser emission intensity at time 0; T saw is the scanning period of the sawtooth wave signal.

5. The method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 1, characterized in that: The corrected second harmonic signal peak value is used to obtain the accurate concentration value of each component gas in the goaf gas, and the formula is as follows: Where P2″ f-0 is the peak value of the second harmonic signal after correction; C is the gas concentration of the component to be measured in the goaf gas; k t is the slope of the outgoing light intensity when there is no coal dust in the gas in the goaf; P is pressure; S(T) is the intensity of the gas absorption line of the component to be measured in the gas of the goaf; L is the effective optical path of the laser in the gas of the goaf; Δv c is the half-height and half-width of the Lorentz line shape; is the average light intensity scanned by the laser; S0(0,m), S2(0,m), and S4(0,m) are all functions of the normalized center frequency detuning amount 0 and the modulation depth m; ΔI2 is the linear and nonlinear light intensity modulation amplitude; is the phase difference between nonlinear light intensity modulation and frequency modulation.

6. A method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 1, characterized in that: The method further includes: performing a spontaneous combustion fire early warning analysis in the goaf of a coal mine according to the concentration of each component gas measured by the laser sensor module and the ambient temperature of the goaf measured by the distributed optical fiber temperature measurement system of the goaf through optical fiber, as follows: If A′(x,y)×B′(x,y)×C′(x,y)×D′(x,y)×E′(x,y)×G′(x,y)+F′(x,y)×H′(x,y)×I′(x,y)≥1, the goaf location (x,y) is a spontaneous combustion fire hazard zone, and a spontaneous combustion fire warning is issued; Where A′(x,y) is the ambient temperature change rate index at the goaf location (x,y); B′(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y); C′(x,y) is the oxygen concentration index at the goaf location (x,y); D′(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y); E′(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y); F′(x,y) is the acetylene concentration index at the goaf location (x,y); G′(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y); H′(x,y) is the ammonia concentration index at the goaf location (x,y); I′(x,y) is the hydrogen sulfide concentration index at the goaf location (x,y).

7. A method for suppressing the influence of coal dust on coal mine gas laser detection according to claim 6, characterized in that: The values ​​of each indicator are as follows: Where A(x,y) is the rate of change of ambient temperature at the goaf location (x,y); d means one day; B(x,y) is the ratio of carbon dioxide concentration to carbon monoxide concentration at the goaf location (x,y); C(x,y) is the oxygen concentration at the goaf location (x,y); D(x,y) is the ratio of ethane concentration to ethylene concentration at the goaf location (x,y); E(x,y) is the ratio of methane concentration to ethane concentration at the goaf location (x,y); F(x,y) is the acetylene concentration at the goaf location (x,y); G(x,y) is the ratio of carbon monoxide concentration to oxygen concentration at the goaf location (x,y); H(x,y) is the ammonia concentration at the goaf location (x,y); I(x,y) is the hydrogen sulfide concentration at the goaf location (x,y).

8. A coal mine gas laser detection device, comprising a monitoring host, a gas extraction and water filtration control box, a power supply box, a network interface and a host computer; wherein the monitoring host, the gas extraction and water filtration control box and the power supply box are arranged in the underground electromechanical chamber; the host computer is arranged above the well and communicates with the monitoring host through the network interface; characterized in that: The monitoring host is powered by a power supply box and is used for on-site detection, display, and over-limit warning of the flow rate of the beam tube gas, the concentration of multiple gases to be measured in the goaf, and the temperature, as well as remote communication with the host computer, and controls the gas extraction and water filtration of the gas extraction and water filtration control box, wherein the concentration of multiple gases to be measured in the goaf is detected based on the coal mine gas laser detection coal dust influence suppression method described in any one of claims 1 to 5; The air extraction and water filtration control box is powered by the power box and is used for extraction, water filtration and flow measurement of the gas from the 8-way bundle pipes. The extracted and water-filtered gas is transported to the monitoring host through the air pipe. Each bundle pipe is equipped with a micro air pump to extract the gas from the 8-way bundle pipes synchronously. The host computer is used for data collection and display from multiple monitoring hosts, early warning of spontaneous combustion of coal mines, and remote control.

9. A coal mine gas laser detection device according to claim 8, characterized in that: The monitoring host adopts a laser gas detection module and utilizes the coal mine gas laser detection coal dust influence suppression method to detect the concentration of nine gas components, including carbon dioxide, oxygen, acetylene, methane, ethylene, carbon monoxide, ethane, ammonia, and hydrogen sulfide, in the beam tube gas; The host computer performs early warning analysis of spontaneous combustion fire in the goaf of the coal mine based on the concentrations of the nine gas components measured by the laser sensor module and the goaf temperature measured by the goaf distributed optical fiber temperature measurement system through optical fiber.

10. A coal mine gas laser detection device according to claim 8, characterized in that: One monitoring host can be connected to up to 2 control boxes to detect up to 16 tube gases.

11. A coal mine gas laser detection device according to claim 8, characterized in that: The monitoring host is connected to the nearby network interface through optical fiber underground, uploads data to the host computer through Ethernet, and receives commands from the host computer; communicates with the air extraction and water filtration control box through RS485, and sends the start and stop control commands of the sampling pump in the control box to the air extraction and water filtration control box.

12. A coal mine gas laser detection device according to claim 8, characterized in that: The micro air pump is a negative pressure suction type intrinsically safe micro air pump.

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