Laser-integrated gas emission amount measuring device and method

Abstract

The application discloses a laser integrated gas emission amount measuring device, which comprises a device main body, a laser emission module and a laser receiving module are assembled at the front end of the device main body, a signal processing module is assembled in the device main body, a man-machine interaction module is assembled at the rear end of the device main body, a power module is assembled in the handle of the device main body, an explosion-proof shell is assembled on the outer side of the device main body, and a laser integrated gas emission amount measuring method is also disclosed. The application adopts integrated design, and the measuring efficiency is greatly improved. Laser Doppler wind measurement and TDLAS methane detection are fused in the same instrument, coaxial and same light path design is adopted, wind speed and methane concentration can be synchronously obtained through one measurement, the instrument automatically calculates and outputs the gas emission amount, manual calculation is not needed, the measurement time is greatly shortened, and the measuring efficiency is greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of coal mine safety monitoring technology, and specifically provides a laser-integrated gas emission measurement device and method. Background Technology

[0002] Gas emission is a core monitoring indicator for coal mine safety production. It is directly related to the life safety of underground workers and the safe production order of the mine. Accurate and rapid measurement of gas emission in roadways is the key to preventing accidents such as gas explosions and gas poisoning. At present, the measurement of gas emission in underground roadways in coal mines mainly adopts the traditional method of separate equipment measurement, which has the following prominent problems: (1) The process is cumbersome and inefficient. The traditional measurement method requires the use of wind speed measuring instruments and methane concentration measuring instruments. First, the wind speed at one or more points in the roadway is measured manually. Then, the methane concentration is measured manually or at fixed points. Finally, the gas emission is calculated by manually substituting it into the formula. The whole process takes a long time and requires on-site operation by workers, which increases the amount of underground work. (2) Low measurement accuracy and large error. In terms of wind speed measurement, only single-point wind speed can be measured, which cannot reflect the average wind speed of the roadway cross section. In terms of methane concentration measurement, traditional detection equipment is mostly contact type. Due to the limitation of the detection point location, it is difficult to obtain the average concentration of the roadway cross section. It is also easily affected by water vapor, dust and other gases, resulting in a large concentration measurement error. At the same time, the wind speed and methane concentration measurements are not synchronized and the measurement areas are not uniform, which further amplifies the calculation error of gas emission and cannot meet the high-precision monitoring requirements. (3) Poor operation safety: Traditional measurement methods require operators to enter the dangerous area of ​​the roadway for close-range contact measurement, which poses safety hazards such as gas poisoning and suffocation. Moreover, contact equipment is used in the high dust, high humidity and high gas environment underground for a long time, which is prone to aging and damage. Frequent maintenance and calibration are required, which increases maintenance costs and operation risks. (4) Unable to achieve real-time linkage: Traditional measuring instruments are mostly independent devices without automatic data calculation, storage and uploading functions. Measurement data needs to be manually recorded, sorted and reported. It is impossible to synchronize with the mine's intelligent ventilation and anti-outburst early warning system in real time. It is difficult to achieve rapid early warning and intelligent ventilation linkage when the gas outburst is abnormal, which is not in line with the trend of intelligent development of coal mines.

[0003] In existing technologies, laser Doppler wind measurement technology has been used for long-distance, non-contact wind speed measurement, offering advantages such as high measurement accuracy, strong anti-interference capability, and no need to contact the airflow. TDLAS technology has been used for high-precision remote measurement of methane concentration, enabling non-contact, long-distance methane concentration measurement resistant to dust and water vapor interference. However, there is currently no technical solution that integrates the two laser technologies to achieve simultaneous measurement of wind speed and methane concentration using the same instrument and optical path, and automatically calculates and outputs the gas emission rate. This fails to address the aforementioned shortcomings of traditional measurement methods. Therefore, developing an integrated, non-contact, high-precision, and fast-response roadway gas emission rate measuring instrument has become an urgent need in the field of coal mine safety monitoring. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a laser-integrated gas emission measurement device and method, achieving "one-time measurement, synchronous acquisition, and automatic calculation." This solves the problems of low efficiency, low accuracy, poor safety, and inability to perform real-time linkage in traditional measurement methods, providing an efficient, accurate, and safe technical means for underground gas safety monitoring in coal mines.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a laser integrated gas emission measurement device, comprising a main body of the device, a laser emitting module and a laser receiving module assembled at the front end of the main body of the device, a signal processing module assembled inside the main body of the device, a human-machine interaction module assembled at the rear end of the main body of the device, a power module assembled inside the handle of the main body of the device, and an explosion-proof shell assembled on the outside of the main body of the device. The laser emitting module is used to emit two coaxial laser beams of different wavelengths, which are used for wind speed measurement and methane concentration measurement, respectively. The laser receiving module is used to receive the echo signal of the laser after it is scattered by dust particles in the tunnel and reflected by the tunnel wall, and then separates and transmits it to the signal processing module. The signal processing module is used to process and solve the received electrical signals to obtain the wind speed and methane concentration, and automatically calculate the gas emission rate. The human-computer interaction module is used to realize parameter input, measurement result display and operation control.

[0006] Furthermore, the laser emission module includes a Doppler wind measurement laser source, a TDLAS methane detection laser source, a coaxial coupler, and a collimator; The Doppler wind measurement laser source uses a DFB distributed feedback laser, which emits near-infrared laser with a wavelength of 1550nm for laser Doppler wind measurement. The TDLAS methane detection laser source uses a DFB distributed feedback laser, which emits near-infrared laser with a wavelength of 1653.7nm for TDLAS methane concentration remote sensing. The coaxial coupler is used to coaxially couple two laser beams to ensure that the two laser beams propagate along the same optical path. The collimator is used to collimate the coaxially coupled laser.

[0007] Furthermore, the laser receiving module includes a receiving lens, a beam splitter, a first detector, and a second detector; The receiving lens is used to collect echo laser signals; The beam splitter is used to separate the echo signal into Doppler wind measurement echo and TDLAS methane detection echo; The first detector is used to receive Doppler echo signals with a wavelength of 1550nm and convert the optical signal into an electrical signal; The second detector is used to receive TDLAS echo signals with a wavelength of 1653.7nm and convert the optical signal into an electrical signal.

[0008] Furthermore, the signal processing module includes a Doppler signal processing module, a TDLAS signal processing module, a laser ranging module, a temperature and pressure sensor, and a main control unit; The Doppler signal processing module is used to extract the Doppler frequency shift signal and calculate the average wind speed v of the tunnel cross section; The TDLAS signal processing module is used to extract the second harmonic signal and, combined with the optical path L measured by the laser ranging module 33, to invert the average methane volume concentration C of the tunnel cross section. The laser ranging module is used to measure the distance from the laser emission point to the tunnel wall to obtain the optical path L; The temperature and pressure sensor is used to correct the values ​​of methane concentration and gas emission. The main control unit is used to coordinate the work of each module and automatically calculate the gas emission rate Q according to a preset formula.

[0009] Furthermore, the human-computer interaction module includes an LCD display screen, operation buttons, an alarm module, a data storage unit, and a data upload unit; The LCD display screen is used to display measurement parameters in real time; The operation buttons are used to start and stop the measurement, input parameters, and calibrate the instrument. The alarm module is used to issue an audible and visual alarm when the methane concentration exceeds a preset threshold or the gas emission is abnormal. The data storage unit is used to automatically store measurement data; The data upload unit is used to upload real-time measurement data to the mine intelligent monitoring system.

[0010] The laser-integrated gas emission measurement device and method, using the aforementioned laser-integrated gas emission measurement device, specifically includes the following steps: Step S1: Power on the instrument and complete the self-test of each module. After the self-test is passed, it enters the standby state. The screen displays the standby interface and prompts you to input the cross-sectional area of ​​the tunnel. Step S2: The operator manually inputs the current tunnel cross-sectional area S by pressing the operation button, or selects from the preset cross-sectional dimensions, and presses the confirmation button after inputting the data. Step S3: Press the measurement button. The instrument starts the laser emission module. The Doppler wind measurement laser and the TDLAS methane detection laser are coupled through the coaxial coupler and then emitted to the tunnel wall through the collimator. When the laser passes through the airflow area in the tunnel, it is scattered by dust particles in the airflow and reflected by the tunnel wall to form an echo signal. In step S4, the laser receiving module collects the echo signal through the receiving lens, and separates it into Doppler echo and TDLAS echo by the beam splitter. The signals are then transmitted to the first detector and the second detector, respectively. The detector converts the optical signal into an electrical signal and transmits it to the signal processing module. Step S5: The signal processing module processes the electrical signal: the Doppler signal processing module extracts the Doppler frequency shift signal and calculates the average wind speed v in the tunnel; the TDLAS signal processing module extracts the second harmonic signal and, combined with the optical path length L measured by the laser ranging module, inverts to obtain the average methane concentration C in the tunnel; the main control unit collects ambient temperature and pressure data and compensates for the wind speed and concentration data. Step S6: The main control unit automatically calculates the gas emission Q according to the preset formula, converts the calculation result into preset units, and transmits it to the human-machine interaction module. Step S7: The LCD screen displays parameters such as wind speed, methane concentration, roadway cross-section, gas emission, and measurement distance in real time; the data storage unit automatically stores the current measurement data; and the data upload unit uploads the real-time data to the mine intelligent monitoring system. Step S8: If the methane concentration exceeds the preset threshold or the gas emission is abnormal during the measurement process, the alarm module will automatically issue an audible and visual alarm to remind the operator to take timely action. After the measurement is completed, press the measurement button to stop the measurement, and the instrument will return to standby mode for the next measurement.

[0011] Furthermore, in step S5, the average wind speed in the tunnel is calculated based on the principle of laser Doppler wind measurement, and the average methane concentration in the tunnel is calculated based on the Lambert-Beer law and combined with optical path inversion.

[0012] Further, in step S6, the preset formula is: ; Where: K t K is the temperature correction factor. p is the pressure correction factor; S is the cross-sectional area of ​​the roadway; v is the average wind speed in the roadway; C is the average methane concentration in the roadway.

[0013] The beneficial effects of using this invention are: This invention adopts an integrated design, which greatly improves measurement efficiency: it integrates laser Doppler wind measurement and TDLAS methane detection into the same instrument, and adopts a coaxial and optical path design. Wind speed and methane concentration can be obtained simultaneously in one measurement. The instrument automatically calculates and outputs the gas emission rate, eliminating the need for separate equipment measurement and manual calculation. The measurement time is shortened to less than 10 seconds, which greatly improves measurement efficiency.

[0014] This invention offers high measurement accuracy and low error: it employs non-contact laser measurement, avoiding the problems caused by airflow and dust in contact equipment; the coaxial and optical path design ensures that the wind speed and methane concentration measurement areas are completely consistent, eliminating errors caused by different measurement areas.

[0015] This invention offers high operational safety and low maintenance costs: its non-contact telemetry design allows operators to complete measurements in safe areas without entering high-risk zones, effectively avoiding safety hazards such as gas poisoning and suffocation; the instrument's non-contact sensors are not prone to aging or damage, eliminating the need for frequent maintenance and calibration, thus reducing maintenance costs.

[0016] This invention is highly intelligent and can achieve real-time linkage: it has built-in data storage, automatic calculation, and audible and visual alarm functions, and supports real-time data uploading to the mine's intelligent system to realize remote monitoring and abnormal early warning of gas emission.

[0017] This invention has a wide range of applications: it adopts explosion-proof, waterproof and dustproof design, and is suitable for different scenarios such as underground roadways, high-risk areas, upper corners and blind alleys in coal mines; it can meet the measurement needs of roadways with different cross-sections and is highly practical. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention.

[0019] Figure 2 This is a schematic diagram of the internal module connections of the device of the present invention.

[0020] Figure 3 This is a schematic diagram illustrating the coaxial and optical path laser fusion principle of the present invention.

[0021] Figure 4 This is a flowchart of the workflow for measuring gas emission from a roadway using a laser-integrated system, as described in this invention.

[0022] The attached reference numerals include: 1. Laser emitting module; 1-1. Doppler wind laser source; 1-2. TDLAS methane detection laser source; 1-3. Coaxial coupler; 1-4. Collimator; 2. Laser receiving module; 2-1. Receiving lens; 2-2. Beam splitter; 2-3. First detector; 2-4. Second detector; 3. Signal processing module; 3-1. Doppler signal processing module; 3-2. TDLAS signal processing module; 3-3. Laser ranging module; 3-4. Temperature and pressure sensor; 3-5. Main control unit; 4. Human-machine interaction module; 4-1. LCD display screen; 4-2. Operation buttons; 4-3. Alarm module; 4-4. Data storage unit; 4-5. Data upload unit; 5. Power module; 6. Explosion-proof housing; 7. USB interface; 8. Power interface. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 Reference Figures 1 to 3 The laser-integrated gas emission measurement device includes a main body, a laser emitting module 1 and a laser receiving module 2 installed at the front end of the main body, a signal processing module 3 installed inside the main body, a human-machine interaction module 4 installed at the rear end of the main body, a power module 5 installed inside the handle of the main body, and an explosion-proof shell 6 installed on the outside of the main body.

[0025] Laser emitting module 1 is used to emit two coaxial laser beams of different wavelengths, used for wind speed measurement and methane concentration measurement respectively; laser receiving module 2 is used to receive the echo signal of the laser after it is scattered by dust particles in the tunnel and reflected by the tunnel wall, and then separates and transmits it to the signal processing module; signal processing module 3 is used to process and solve the received electrical signal to obtain the wind speed and methane concentration, and automatically calculate the gas emission rate; human-machine interaction module 4 is used to realize parameter input, measurement result display and operation control.

[0026] The power module 5 is powered by a lithium battery and supports fast charging. It also supports external power supply to adapt to different power supply scenarios underground. The explosion-proof housing 6 is made of explosion-proof, waterproof and dustproof material to adapt to the harsh environment of high dust, high humidity and high gas in coal mines. The explosion-proof housing 6 is also equipped with a USB interface 7 and a power interface 8.

[0027] Specifically, the laser emission module 1 includes a Doppler wind measurement laser source 1-1, a TDLAS methane detection laser source 1-2, a coaxial coupler 1-3, and a collimator 1-4.

[0028] The Doppler wind measurement laser source 1-1 adopts a DFB distributed feedback laser, which emits a near-infrared laser with a wavelength of 1550nm for laser Doppler wind measurement; the output power of the laser source is adjustable to meet the measurement needs of different roadway distances.

[0029] The TDLAS methane detection laser source 1-2 uses a DFB distributed feedback laser to emit near-infrared laser with a wavelength of 1653.7nm for TDLAS methane concentration remote sensing. The laser source is superimposed with a high-frequency sinusoidal current to achieve a small wavelength scan, covering the characteristic absorption peak of methane and improving the selectivity and sensitivity of concentration measurement.

[0030] Coaxial couplers 1-3 are used to coaxially couple two laser beams, ensuring that the two laser beams propagate along the same optical path and pass through the same airflow area in the tunnel, thus ensuring the spatial consistency of wind speed and methane concentration measurements and avoiding calculation errors caused by different measurement areas.

[0031] Collimators 1-4 are used to collimate the coaxially coupled laser beam, reduce laser beam divergence, and improve laser propagation distance and measurement accuracy. The diameter of the collimated laser beam is 1-3 mm.

[0032] Specifically, the laser receiving module 2 includes a receiving lens 2-1, a beam splitter 2-2, a first detector 2-3, and a second detector 2-4.

[0033] The receiving lens 2-1 adopts a convex lens structure with an adjustable focal length (range: 50-200mm) to collect echo laser signals and improve signal reception efficiency; the lens surface is coated with an anti-reflection film to reduce stray light interference.

[0034] The beam splitter 2-2 uses a wavelength splitter to separate the echo signal into a Doppler wind echo and a TDLAS methane detection echo based on the wavelength difference between the two laser beams (1550nm and 1653.7nm), which are then transmitted to their respective detectors.

[0035] The first detector 2-3 uses an InGaAs photodetector to receive Doppler echo signals at a wavelength of 1550nm, converting the optical signal into an electrical signal with a response time ≤0.1μs, ensuring a fast response for wind speed measurement.

[0036] The second detector 2-4 is an InGaAs photodetector used to receive TDLAS echo signals with a wavelength of 1653.7nm, converting the optical signal into an electrical signal with a response time ≤0.1μs. It is used in conjunction with a lock-in amplifier circuit to achieve second harmonic demodulation.

[0037] Specifically, the signal processing module 3 includes a Doppler signal processing module 3-1, a TDLAS signal processing module 3-2, a laser ranging module 3-3, a temperature and pressure sensor 3-4, and a main control unit 3-5.

[0038] The Doppler signal processing module 3-1 amplifies, filters, and mixes the electrical signal output by the first detector to extract the Doppler frequency shift signal; based on the principle of laser Doppler wind measurement, the average wind speed v of the tunnel cross section is calculated through a preset algorithm.

[0039] The TDLAS signal processing module 3-2 performs phase-locked amplification on the electrical signal output by the second detector and extracts the second harmonic signal. Based on the Lambert-Beer law and combined with the optical path L measured by the laser ranging module 3-3, the average methane volume concentration C of the tunnel cross section is obtained by inversion.

[0040] The laser ranging module 3-3 integrates a laser ranging sensor to measure the distance from the laser emission point to the tunnel wall, obtaining the optical path length L, which provides data support for methane concentration inversion.

[0041] Temperature and pressure sensors 3-4 integrate temperature and pressure sensors to correct values ​​for methane concentration and gas emission.

[0042] The main control unit 3-5 uses a high-performance chip to coordinate the work of each module. It receives data from the Doppler signal processing module 3-1, the TDLAS signal processing module 3-2, the laser rangefinder sensor 3-3, the temperature and pressure sensor 3-4, and the tunnel cross-sectional area S input by the human-machine interaction module 4. It also automatically calculates the gas emission rate Q in real time according to a preset formula.

[0043] Specifically, the human-computer interaction module 4 includes an LCD display screen 4-1, operation buttons 4-2, an alarm module 4-3, a data storage unit 4-4, and a data upload unit 4-5.

[0044] LCD Display 4-1 adopts an industrial-grade high-definition LCD display, which can display parameters such as wind speed, methane concentration, tunnel cross-sectional area, gas emission, and measurement distance in real time. The screen brightness is adjustable to adapt to the dim underground environment.

[0045] The operation buttons 4-2 include a power button, a measurement button, a parameter setting button, and a unit switching button, which are used to start / stop measurement, input the cross-sectional area of ​​the roadway, switch measurement units, and calibrate the instrument.

[0046] Alarm module 4-3 is used to issue an audible and visual alarm when the methane concentration exceeds a preset threshold or the gas emission is abnormal, so as to remind the operators to take timely action.

[0047] Data storage unit 4-4 has a built-in high-capacity storage chip for automatically storing measurement data (including wind speed, methane concentration, gas emission, measurement time, measurement location, etc.), with a storage time of ≥1 year and support for data export.

[0048] Data upload units 4-5 integrate 5G or Ethernet modules to upload real-time measurement data to the mine intelligent monitoring system, enabling data sharing and remote monitoring; they support offline storage and automatically re-upload data after network recovery; the mine intelligent monitoring system includes a mine intelligent ventilation system, an anti-outburst early warning system, etc.

[0049] Example 2 Reference Figure 4 The laser-integrated gas emission measurement device and method, using the laser-integrated gas emission measurement device in Example 1, specifically includes the following steps: Step S1: Power on the instrument and complete the self-test of the laser emitting module 1, laser receiving module 2, signal processing module 3, and human-machine interaction module 4. After the self-test is passed, it enters the standby state, and the screen displays the standby interface, prompting the user to input the cross-sectional area of ​​the tunnel.

[0050] In step S2, the operator manually inputs the current tunnel cross-sectional area S by pressing the operation button, or selects from the preset cross-sectional dimensions, and presses the confirmation button after inputting the data.

[0051] Step S3: Press the measurement button. The instrument starts the laser emission module 1. The Doppler wind measurement laser and the TDLAS methane detection laser are coupled through the coaxial coupler 1-3 and then emitted to the tunnel wall through the collimator 1-4. When the laser passes through the airflow area in the tunnel, it is scattered by dust particles in the airflow and reflected by the tunnel wall to form an echo signal.

[0052] In step S4, the laser receiving module 2 collects the echo signal through the receiving lens 2-1, and separates it into Doppler echo and TDLAS echo through the beam splitter 2-2. The signals are then transmitted to the first detector 2-3 and the second detector 2-4, respectively. The detectors convert the optical signal into an electrical signal and transmit it to the signal processing module 3.

[0053] Step S5: Signal processing module 3 processes the electrical signal: Doppler signal processing module 3-1 extracts the Doppler frequency shift signal and calculates the average wind speed v in the tunnel; TDLAS signal processing module 3-2 extracts the second harmonic signal and, combined with the optical path length L measured by laser ranging module 3-3, inverts to obtain the average methane concentration C in the tunnel; main control unit 3-5 collects ambient temperature and pressure data and compensates for the wind speed and concentration data. Among them, the average wind speed in the tunnel is calculated based on the principle of laser Doppler wind measurement, and the average methane concentration in the tunnel is calculated based on Lambert-Beer law and combined with optical path inversion.

[0054] In step S6, the main control unit 3-5 automatically calculates the gas emission amount Q according to the preset formula, converts the calculation result into a preset unit, and transmits it to the human-machine interaction module 4. The preset formula is: ; Where: K t K is the temperature correction factor. p S is the pressure correction factor; S is the cross-sectional area of ​​the roadway (m²). 2 v is the average wind speed in the roadway (m / s); C is the average methane concentration in the roadway (%); Q is the gas emission rate (m³ / s). 3 / min).

[0055] The national standard specifies the standard operating condition as T0 = 293.15 K (20℃) and standard atmospheric pressure P0 = 101.325 kPa. Under this condition, K... t =1、K p =1; Downhole conditions are non-standard temperature and pressure conditions, and the gas molar volume and the intensity of the methane infrared absorption peak shift, so double coefficient correction must be performed.

[0056] The temperature correction factor is adjusted using both spectral absorption temperature compensation and gas volume correction to match the 1653.7 nm methane characteristic peak. The formula for calculating the temperature correction factor is as follows: ; in: T0 is the standard calibration thermodynamic temperature, which is fixed at 293.15 K; T represents the real-time downhole thermodynamic temperature, measured by temperature and pressure sensor 3-4 (unit: K, downhole temperature range: 273.15 K to 313.15 K). The TDLAS spectral temperature shift correction factor is set to 0.96–1.04 for the methane absorption peak at 1653.7 nm, and 1 at room temperature (20 °C).

[0057] The pressure correction factor is derived from the ideal gas law and is suitable for negative pressure roadways in mines. The formula for calculating the pressure correction factor is: ; in: P0 is the standard atmospheric pressure, fixed at 101.325 kPa; P represents the real-time absolute air pressure in the tunnel, collected in real-time by the sensor (unit: kPa; underground tunnel air pressure: 90–115 kPa).

[0058] Step S7: The LCD display screen 4-1 displays parameters such as wind speed, methane concentration, roadway cross-section, gas emission, and measurement distance in real time; the data storage unit 4-4 automatically stores the current measurement data; and the data upload unit 4-5 uploads the real-time data to the mine intelligent monitoring system.

[0059] Step S8: If the methane concentration exceeds the preset threshold or the gas emission is abnormal during the measurement process, the alarm module 4-3 will automatically issue an audible and visual alarm to remind the operator to handle the situation in time. After the measurement is completed, press the measurement button to stop the measurement, and the instrument will return to standby mode for the next measurement.

[0060] Example 3 This embodiment provides a gas emission measurement instrument based on laser-integrated technology, suitable for measuring gas emission in underground coal mine longwall mining faces, tunneling roadways, and high-risk areas. Specific parameters are as follows: measurement distance 5-200m, methane concentration measurement range 0-100%CH4, and gas emission calculation range 0-100m. 3 / min, with a battery life of ≥8 hours.

[0061] Regarding laser emitting module 1, specifically: (1) Doppler wind measurement laser source 1-1, model DFB-1550, output power 30mW, wavelength 1550nm, linewidth ≤1MHz, working temperature -20℃-60℃, suitable for the temperature requirements of the downhole environment. (2) TDLAS methane detection laser source 1-2, model DFB-1653.7, output power 20mW, wavelength 1653.7nm, accurately matching the characteristic absorption peak of methane, superimposed with 20kHz high frequency sinusoidal current, wavelength scanning range ±0.002nm, to ensure coverage of methane absorption peak; (3) Coaxial couplers 1-3 are fiber couplers with a coupling efficiency of ≥95% and an insertion loss of ≤0.5dB, ensuring that the two laser beams propagate coaxially without optical path offset; (4) Collimators 1-4, focal length 100mm, after collimation the laser beam diameter 2mm, divergence angle ≤0.5mrad, ensure that the laser spot diameter ≤10cm after 200m propagation, and ensure measurement accuracy.

[0062] Regarding laser receiver module 2, specifically: (1) The receiving lens 2-1 has a diameter of 50mm and a focal length of 100mm. The lens surface is coated with a dual-wavelength anti-reflection film of 1550nm and 1653.7nm with a reflectivity of ≤1% to reduce stray light interference. (2) Beam splitter 2-2, wavelength beam splitter, with a transmittance of ≥90% for 1550nm laser and a reflectance of ≥90% for 1653.7nm laser, to achieve efficient separation of the two echo signals; (3) The first detector 2-3, model InGaAs-PD-1550, has a response wavelength of 1200-1700nm and a response time of 0.05μs to ensure fast and stable reception of Doppler signals; (4) The second detector 2-4, model InGaAs-PD-1653, has a response wavelength of 1500-1800nm ​​and a response time of 0.05μs. It is used in conjunction with a lock-in amplifier circuit to achieve second harmonic demodulation.

[0063] Regarding signal processing module 3, specifically: (1) Doppler signal processing module 3-1 amplifies and low-pass filters the electrical signal with a cutoff frequency of 100kHz, extracts the Doppler frequency shift signal, and calculates the wind speed. The calculation algorithm adopts fast Fourier transform, and the calculation accuracy is ≤±0.05m / s. (2) TDLAS signal processing module 3-2 uses a lock-in amplifier to extract the second harmonic signal. The lock-in amplification factor is 106 times and the signal-to-noise ratio is ≥60dB. Combined with laser ranging data, the methane concentration is inverted and the measurement accuracy is ≤±0.01%CH4. (3) Laser ranging module 3-3, which adopts a pulsed laser ranging sensor, has a measurement range of 5-200m, a measurement accuracy of ±0.1m, a response time of ≤10ms, and outputs optical path length L data in real time; (4) The main control unit 3-5 coordinates the synchronous operation of each module; the built-in temperature and pressure sensor 3-4 collects ambient temperature and pressure in real time, and compensates for methane concentration and wind speed measurement data to reduce the impact of environmental factors.

[0064] Regarding human-computer interaction module 4, the specific details are as follows: (1) LCD Display 4-1, 3.5-inch industrial-grade LCD display, resolution 800×480, brightness ≥500cd / m² 2 Real-time displayed parameters include: wind speed (m / s), methane concentration (%), and tunnel cross-section (m). 2 ), gas emission (m³) 3 ( / min), measurement distance (m), measurement time, and battery level; (2) Operation buttons 4-2, 5 physical buttons: power, measurement, setting, confirmation, unit switching, the buttons are waterproof and dustproof; the setting button can enter the parameter setting interface to customize the methane concentration alarm threshold, measurement unit, etc. (3) Alarm module 4-3 is equipped with a buzzer and a red LED alarm light. When the methane concentration or gas emission exceeds the threshold, the sound and light alarm will be automatically triggered. (4) Data storage unit 4-4 and data upload unit 4-5 have built-in storage chips and can store ≥1 million measurement data; they integrate 5G modules, the upload frequency can be set (1-60 seconds / time), support Ethernet backup, and can be connected to the mine safety monitoring system.

[0065] Regarding power module 5, it specifically features a 12V / 10000mAh lithium battery with a charging time of ≤3 hours and a battery life of ≥8 hours; the external power interface supports 12-24VDC input and is compatible with explosion-proof power supplies for underground mining.

[0066] Regarding the explosion-proof housing 6, it is made of aluminum alloy with a powder-coated surface, has an explosion-proof rating of ExiaIMa, a protection rating of IP65, and a weight of ≤3kg, making it easy for operators to carry. The housing is equipped with a non-slip handle for convenient underground operation.

[0067] Implementation effect verification: The gas emission meter in this embodiment was used in a coal mine longwall face roadway (12m cross-section). 2 On-site testing was conducted, and a comparative test was performed using a traditional measurement method (mechanical anemometer + methane detector). The test results are as follows: (1) Measurement results of the instrument of this invention: wind speed 5.52 m / s, methane concentration 0.28% CH4, gas emission 11.13 m³ / s. 3 / min; (2) Measurement results using traditional methods: Using an S-curve for wind measurement, the average wind speed was measured to be 5.48 m / s. The average methane concentration was measured at three points (upper, middle, and lower) to be 0.29%, and the gas emission rate was 11.44 m³ / s. 3 / min; (3) Comparative analysis: The measurement error of the instrument of the present invention is ≤ ±5%, which is basically consistent with the measurement results of the traditional method. However, the measurement time is shortened from 20 minutes to less than 1 minute, and no workers need to enter the dangerous area, which greatly improves safety and efficiency. At the same time, the instrument of the present invention measures the average wind speed and average concentration of the tunnel cross section, which is more in line with the actual working conditions and the measurement accuracy is more stable.

[0068] The above content is only a preferred embodiment of the present invention. For those skilled in the art, many changes can be made in the specific implementation and application scope based on the concept of the present invention. As long as these changes do not depart from the concept of the present invention, they all fall within the protection scope of the present invention.

Claims

1. A laser-integrated gas emission measurement device, characterized in that: The device includes a main body, with a laser emitting module and a laser receiving module installed at the front end, a signal processing module installed inside the main body, a human-machine interaction module installed at the rear end, a power module installed inside the handle, and an explosion-proof shell installed on the outside of the main body. The laser emitting module is used to emit two coaxial laser beams of different wavelengths, which are used for wind speed measurement and methane concentration measurement, respectively. The laser receiving module is used to receive the echo signal of the laser after it is scattered by dust particles in the tunnel and reflected by the tunnel wall, and then separates and transmits it to the signal processing module. The signal processing module is used to process and solve the received electrical signals to obtain the wind speed and methane concentration, and automatically calculate the gas emission rate. The human-computer interaction module is used to realize parameter input, measurement result display and operation control.

2. The laser-integrated gas emission measurement device according to claim 1, characterized in that: The laser emission module includes a Doppler wind measurement laser source, a TDLAS methane detection laser source, a coaxial coupler, and a collimator. The Doppler wind measurement laser source uses a DFB distributed feedback laser, which emits near-infrared laser with a wavelength of 1550nm for laser Doppler wind measurement. The TDLAS methane detection laser source uses a DFB distributed feedback laser, which emits near-infrared laser with a wavelength of 1653.7nm for TDLAS methane concentration remote sensing. The coaxial coupler is used to coaxially couple two laser beams to ensure that the two laser beams propagate along the same optical path. The collimator is used to collimate the coaxially coupled laser.

3. The laser-integrated gas emission measurement device according to claim 1, characterized in that: The laser receiving module includes a receiving lens, a beam splitter, a first detector, and a second detector; The receiving lens is used to collect echo laser signals; The beam splitter is used to separate the echo signal into Doppler wind measurement echo and TDLAS methane detection echo; The first detector is used to receive Doppler echo signals with a wavelength of 1550nm and convert the optical signal into an electrical signal; The second detector is used to receive TDLAS echo signals with a wavelength of 1653.7nm and convert the optical signal into an electrical signal.

4. The laser-integrated gas emission measurement device according to claim 1, characterized in that: The signal processing module includes a Doppler signal processing module, a TDLAS signal processing module, a laser ranging module, a temperature and pressure sensor, and a main control unit; The Doppler signal processing module is used to extract the Doppler frequency shift signal and calculate the average wind speed v of the tunnel cross section; The TDLAS signal processing module is used to extract the second harmonic signal and, in combination with the optical path L measured by the laser ranging module, to invert the average methane volume concentration C of the tunnel cross section. The laser ranging module is used to measure the distance from the laser emission point to the tunnel wall to obtain the optical path L; The temperature and pressure sensor is used to correct the values ​​of methane concentration and gas emission. The main control unit is used to coordinate the work of each module and automatically calculate the gas emission rate Q according to a preset formula.

5. The laser-integrated gas emission measurement device according to claim 1, characterized in that: The human-computer interaction module includes an LCD display screen, operation buttons, an alarm module, a data storage unit, and a data upload unit; The LCD display screen is used to display measurement parameters in real time; The operation buttons are used to start and stop the measurement, input parameters, and calibrate the instrument. The alarm module is used to issue an audible and visual alarm when the methane concentration exceeds a preset threshold or the gas emission is abnormal. The data storage unit is used to automatically store measurement data; The data upload unit is used to upload real-time measurement data to the mine intelligent monitoring system.

6. A laser-integrated gas emission measurement device and method, employing the laser-integrated gas emission measurement device as described in any one of claims 1 to 5, specifically comprising the following steps: Step S1: Power on the instrument and complete the self-test of each module. After the self-test is passed, it enters the standby state. The screen displays the standby interface and prompts you to input the cross-sectional area of ​​the tunnel. Step S2: The operator manually inputs the current tunnel cross-sectional area S by pressing the operation button, or selects from the preset cross-sectional dimensions, and presses the confirmation button after inputting the data. Step S3: Press the measurement button. The instrument starts the laser emission module. The Doppler wind measurement laser and the TDLAS methane detection laser are coupled through the coaxial coupler and then emitted to the tunnel wall through the collimator. When the laser passes through the airflow area in the tunnel, it is scattered by dust particles in the airflow and reflected by the tunnel wall to form an echo signal. In step S4, the laser receiving module collects the echo signal through the receiving lens, and separates it into Doppler echo and TDLAS echo by the beam splitter. The signals are then transmitted to the first detector and the second detector, respectively. The detector converts the optical signal into an electrical signal and transmits it to the signal processing module. Step S5: The signal processing module processes the electrical signal: the Doppler signal processing module extracts the Doppler frequency shift signal and calculates the average wind speed v in the tunnel; the TDLAS signal processing module extracts the second harmonic signal and, combined with the optical path length L measured by the laser ranging module, inverts to obtain the average methane concentration C in the tunnel; the main control unit collects ambient temperature and pressure data and compensates for the wind speed and concentration data. Step S6: The main control unit automatically calculates the gas emission Q according to the preset formula, converts the calculation result into preset units, and transmits it to the human-machine interaction module. Step S7: The LCD screen displays parameters such as wind speed, methane concentration, roadway cross-section, gas emission, and measurement distance in real time; the data storage unit automatically stores the current measurement data; and the data upload unit uploads the real-time data to the mine intelligent monitoring system. Step S8: If the methane concentration exceeds the preset threshold or the gas emission is abnormal during the measurement process, the alarm module will automatically issue an audible and visual alarm to remind the operator to take timely action. After the measurement is completed, press the measurement button to stop the measurement, and the instrument will return to standby mode for the next measurement.

7. The laser-integrated gas emission measurement method according to claim 6, characterized in that: In step S5, the average wind speed in the tunnel is calculated based on the principle of laser Doppler wind measurement, and the average methane concentration in the tunnel is calculated based on Beer-Lambert's law and optical path inversion.

8. The laser-integrated gas emission measurement method according to claim 6, characterized in that: In step S6, the preset formula is: ； Where: K t K is the temperature correction factor. p is the pressure correction factor; S is the cross-sectional area of ​​the roadway; v is the average wind speed in the roadway; C is the average methane concentration in the roadway.

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