All-laser methane and carbon monoxide detection device and method for drilling extraction

Abstract

This invention discloses a full-laser methane and carbon monoxide detection device for borehole extraction, comprising: a connecting pipe, a gas buffer pool connected to one end of the connecting pipe, a methane sensor assembly, a carbon monoxide sensor assembly, a control and processing module, a transmission module, and a power supply module; the methane sensor assembly and the carbon monoxide sensor assembly are fixedly arranged side by side on the top of the cavity-structured gas buffer pool, and the gas to be detected is supplied to them by the gas buffer pool through a gas exchange membrane; the control and processing module is connected to the methane sensor assembly, the carbon monoxide sensor assembly, the transmission module, and the power supply module; the corresponding detection method is also disclosed; it can accurately pick up photoacoustic signals in complex acoustic field environments downhole, realize full-range detection of methane concentration and high-precision detection of trace carbon monoxide; and reduce system complexity and device size.

Description

Technical Field

[0001] This invention relates to the field of gas detection, specifically to a full-laser methane and carbon monoxide detection device and method for borehole extraction. Background Technology

[0002] Borehole extraction is an effective measure to prevent gas-related disasters. The main component of gas is methane, but it also contains small amounts of ethane, propane, and other gases. Furthermore, negative pressure extraction in boreholes can easily trigger spontaneous combustion of coal seams, a process accompanied by the production of carbon monoxide. Statistics show that methane and carbon monoxide are the leading causes of underground fires, explosions, poisoning, and asphyxiation accidents. To ensure safe and efficient mining, it is necessary to monitor methane and carbon monoxide gases in the borehole extraction pipelines.

[0003] With the intelligent development of the coal mining industry and the increase in mining depth, coal mining enterprises attach great importance to underground safety, leading to a continuous increase in the demand for borehole gas detection. However, existing borehole gas detection equipment still has many shortcomings. First, traditional gas detection equipment is large in size, occupies a lot of space, is difficult to maintain, and consumes a lot of power. Installing and deploying this equipment in confined spaces such as narrow underground roadways is extremely inconvenient. Second, infrared absorption spectroscopy sensors are mostly used for full-range methane detection; their limited gas pool volume cannot detect trace gases. Therefore, sensors for detecting trace carbon monoxide in boreholes mostly rely on electrochemical or catalytic combustion principles, resulting in insufficient sensitivity and accuracy.

[0004] Continuous technological innovation has led to significant advancements in laser technology and weak signal detection techniques. Photoacoustic spectroscopy, based on the photoacoustic effect, inverts gas concentration by detecting acoustic signals. However, the complex gas environment and strong noise interference downhole make this method challenging to apply. Furthermore, some solutions suffer from large size, making them inconvenient for downhole installation. Summary of the Invention

[0005] The purpose of this invention is to provide an accurate and reliable online detection device for methane and carbon monoxide gas concentrations in borehole extraction gas, addressing the problems of low accuracy and large size of existing downhole gas detection technologies.

[0006] The present invention provides the following solution: a full-laser methane and carbon monoxide detection device for borehole extraction, comprising: a connecting pipe, a gas buffer pool connected to one end of the connecting pipe, a methane sensor assembly, a carbon monoxide sensor assembly, a control and processing module, and a transmission module including a wireless transmission module, a wired transmission module, and a power supply module; the methane sensor assembly and the carbon monoxide sensor assembly are fixedly arranged side by side on the top of the cavity-structured gas buffer pool, and the gas to be detected is provided to both by the gas buffer pool through a gas exchange membrane; the control and processing module is connected to the methane sensor assembly, the carbon monoxide sensor assembly, the transmission module, and the power supply module;

[0007] The methane sensor assembly includes a cavity-structured gas cell; a MEMS infrared light source and an infrared detector, centered at the same height, are respectively embedded in the center of the left and right cavity walls of the gas cell. The carbon monoxide sensor assembly includes a cavity-structured photoacoustic cell; a first MEMS microphone is embedded in the center of the top of the photoacoustic cell, and a second MEMS microphone is embedded in the center of the rear side; the first and second MEMS microphones form a spatial array; the gas exchange membrane at the connection between the photoacoustic cell and the gas buffer cell is horizontally offset from the first MEMS microphone to reduce the influence of gas flow on the photoacoustic signal received by the MEMS microphone; a MEMS infrared laser is embedded in the center of the right side of the photoacoustic cell; the sinusoidal modulation signals of the EMS infrared light source and the MEMS infrared laser have the same frequency.

[0008] It also includes a display module connected to the control processing module and an explosion-proof housing; the gas buffer tank, methane sensor, carbon monoxide sensor, control processing module, transmission module, and power supply module are all housed within the explosion-proof housing;

[0009] Furthermore, the MEMS infrared laser, the first MEMS microphone, the second MEMS microphone, the MEMS infrared light source, and the infrared detector all have interface circuits at their tail ends, with relevant pins connected to the control and processing module.

[0010] Furthermore, a high-reflectivity window is fixed to the center of the left side of the photoacoustic cell via a cover plate to increase the optical path and improve detection sensitivity. The high-reflectivity window and the MEMS infrared laser are at the same horizontal level.

[0011] Furthermore, a first through-channel structure is provided at the connection between the gas pool body and the gas buffer pool; a first gas exchange membrane is provided in the first through-channel structure, through which gas in the gas buffer pool can enter the gas pool; a second through-channel structure is provided at the connection between the photoacoustic pool body and the gas buffer pool, through which a second gas exchange membrane is provided, through which gas in the gas buffer pool can enter the photoacoustic pool; the gas exchange membrane further prevents coal dust from entering and reduces the noise of gas exchange.

[0012] Furthermore, it also includes a water and dust filter installed on the connecting pipe, comprising a water filter and a dust filter.

[0013] Furthermore, the gas buffer pool has a central opening at the bottom, which is connected to a connecting pipe; the bottom of the gas buffer pool cavity slopes downward toward the central opening to prevent dust from accumulating inside the gas buffer pool.

[0014] Furthermore, the control processing module includes a laser control circuit, a photoacoustic signal preprocessing circuit, a lock-in amplifier circuit, and a central processing circuit; the laser control circuit includes a laser modulation circuit and a laser temperature control circuit.

[0015] The laser modulation circuit can generate sinusoidal modulation signals and sawtooth wave signals or triangular wave signals to modulate the MEMS infrared light source and MEMS infrared laser.

[0016] The laser temperature control circuit regulates the temperature of the MEMS infrared light source and the MEMS infrared laser, respectively.

[0017] The photoacoustic signal preprocessing circuit performs time delay processing on the photoacoustic signal received by the second MEMS microphone, and then performs addition, subtraction, time-frequency decomposition and other operations with the photoacoustic signal received by the first MEMS microphone to obtain the target photoacoustic signal, so as to further reduce the strong noise interference in the downhole environment and the noise interference in the photoacoustic cell, and improve the detection limit of trace carbon monoxide.

[0018] The lock-in amplifier circuit receives the signal from the infrared detector and the photoacoustic signal processed by the photoacoustic signal preprocessing circuit, locks in and amplifies its second harmonic f signal.

[0019] The central processing circuit is used to acquire and process second harmonic signals, and to store and transmit the gas concentration results obtained from the processing.

[0020] Furthermore, the sinusoidal modulation signal frequency is designed based on the photoacoustic cell resonant frequency. This is because the sinusoidal modulation signal frequency has a greater impact on carbon monoxide sensors based on photoacoustic spectroscopy than on methane sensors based on absorption spectroscopy. Therefore, in this embodiment, a single DDS chip is sufficient to generate the sinusoidal modulation signal in the laser modulation circuit.

[0021] Furthermore, the MEMS infrared laser emits laser wavelengths including, but not limited to, 1567nm and 4.67μm, to excite carbon monoxide gas and generate photoacoustic signals; the MEMS infrared light source has wavelengths including, but not limited to, 1653nm and 3.4μm, to excite methane gas.

[0022] As another aspect of the present invention, a method for detecting methane and carbon monoxide using a full-laser method for borehole extraction is also provided, comprising the following steps:

[0023] Step 1: Preparation

[0024] Ensure that all components, including connecting pipes, water and dust filters, gas buffer tanks, methane sensors, carbon monoxide sensors, control processing modules, display modules, wireless transmission modules, wired transmission modules, and power supply modules, are correctly installed and connected; provide power to the device through the power supply module to ensure normal equipment startup; calibrate the methane and carbon monoxide sensors as needed to ensure detection accuracy;

[0025] Step 2: Connect the extraction pipeline

[0026] Connecting pipes: Connect one end of the connecting pipe to the underground extraction pipeline in the coal mine, ensuring a tight and leak-free connection;

[0027] Check for airtightness: Confirm that the connection points of the connecting pipes are properly sealed to prevent gas leakage from affecting the test results;

[0028] Step 3: Start the detection device

[0029] Turn on the device power and start the laser control circuit and photoacoustic signal preprocessing circuit in the control processing module; perform initial settings through the display module, including detection parameters and transmission mode;

[0030] Step 4: Gas extraction and filtration

[0031] Downhole gas is transported to the detection device through extraction pipelines; the gas first passes through a water dust filter to remove moisture and impurities, preventing damage to the sensor;

[0032] Step 5: Gas Detection

[0033] Methane detection:

[0034] The gas enters the methane sensor through a gas buffer pool;

[0035] MEMS infrared light source excites methane gas, and infrared detector detects the generated spectral signal;

[0036] The control processing module processes the signal and calculates the methane concentration;

[0037] Carbon monoxide detection:

[0038] The gas enters the carbon monoxide sensor through a gas buffer pool;

[0039] MEMS infrared lasers excite carbon monoxide gas to generate photoacoustic signals;

[0040] The first and second MEMS microphones receive photoacoustic signals, the control processing module processes the signals, and calculates the carbon monoxide concentration.

[0041] Step Six: Data Processing and Display

[0042] The central processing circuit of the control processing module collects and processes signals from the methane and carbon monoxide sensors to calculate the gas concentration; the processing results are displayed through the display module, including the real-time concentrations of methane and carbon monoxide.

[0043] The beneficial effects and features of this invention are:

[0044] (1) The all-laser methane and carbon monoxide detection device for borehole extraction of the present invention uses absorption spectroscopy technology and its derived photoacoustic spectroscopy method to detect the concentration of methane and carbon monoxide in borehole extracted gas, realizes full-range detection of methane concentration and high-precision detection of trace carbon monoxide, can solve the problem of accurate detection of trace carbon monoxide in borehole extraction, provide reliable data for coal spontaneous combustion early warning, and has the advantages of high gas selectivity, high stability, fast response speed and adaptability to complex environment.

[0045] (2) The all-laser methane and carbon monoxide detection device for borehole extraction of the present invention has a carbon monoxide sensor with a thick photoacoustic cell, which can achieve shock resistance and noise isolation, and adopts a dual-microphone spatial array to further reduce noise, and can accurately pick up photoacoustic signals in complex acoustic field environments downhole.

[0046] (3) The all-laser methane and carbon monoxide detection device for borehole extraction of the present invention drives the sinusoidal modulation signal frequency of the methane sensor light source and the carbon monoxide sensor light source to be consistent, which unifies and simplifies the dual-source laser modulation circuit and lock-in amplifier circuit in sensors with different spectral principles, and helps to reduce system complexity and device size. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of a borehole extraction all-laser methane and carbon monoxide detection device according to a preferred embodiment of the present invention.

[0048] Figure 2 This is a schematic diagram illustrating the structure and connection method of the gas buffer tank, methane sensor, and carbon monoxide sensor according to a preferred embodiment of the present invention.

[0049] Figure 3 This is a schematic diagram of the control processing module circuit of a preferred embodiment of the present invention.

[0050] The reference numerals in the figure represent: 1-connecting pipe, 2-water dust filter, 3-gas buffer tank, 4-methane sensor, 4-1-first gas exchange membrane, 4-2-MEMS infrared light source, 4-3-infrared detector, 4-4-gas tank body, 4-5-gas tank, 5-oxide monoxide detector sensor, 5-1-second gas exchange membrane, 5-2-MEMS infrared laser, 5-3-high reflectivity window, 5-4-cover plate, 5-5-first MEMS microphone, 5-6-second MEMS... S-microphone, 5-7-photoacoustic cell body, 5-8-photoacoustic cell, 6-control processing module, 6-1-laser control circuit, 6-1-1-laser modulation circuit, 6-1-2-laser temperature control circuit, 6-2-photoacoustic signal preprocessing circuit, 6-3-phase-locked loop amplifier circuit, 6-4-central processing circuit, 7-display module, 8-wireless transmission module, 9-wired transmission module, 10-power supply module, 11-explosion-proof housing, 12-first through-channel structure, 13-second through-channel structure. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0052] Please refer to Figure 1 The embodiments of the present invention relate to a full-laser methane and carbon monoxide detection device for borehole extraction, including a connecting pipe 1, a water dust filter 2, and a gas buffer tank 3, a methane sensor 4, a carbon monoxide sensor 5, a control processing module 6, a display module 7, a wireless transmission module 8, a wired transmission module 9, and a power supply module 10 installed in an explosion-proof housing 11.

[0053] One end of the connecting pipe 1 is connected to the extraction pipeline, and the connection method includes, but is not limited to, connecting to the gas intake valve, inserting into the pipeline through a single hole, etc. The other end of the connecting pipe 1 is connected to the water and dust filter 2.

[0054] The gas buffer tank 3 has a central opening at the bottom, which is connected to the water dust filter 2. The bottom of the gas buffer tank 3 has a certain inclination towards the center to prevent dust from accumulating inside.

[0055] The power supply module 10 is connected to the control processing module 6 and is powered by an intrinsically safe battery.

[0056] Please refer to Figure 2 The gas buffer pool 3 has two internal threaded holes at the top, which are fastened to the external threaded posts at the bottom of the gas pool body 4-4 and the photoacoustic pool body 5-7, respectively.

[0057] As a preferred embodiment, the gas pool body 4-4 has a first gas exchange membrane 4-1 bonded to the threaded connection to facilitate gas entry and exit.

[0058] As a preferred option, the gas tank body 4-4 is made of metal, including but not limited to brass and stainless steel.

[0059] As a preferred embodiment, a MEMS infrared light source 4-2 with wavelengths including, but not limited to, 1653 nm and 3.4 μm is embedded in the center of the left side of the gas cell body 4-4 to excite methane gas. An infrared detector 4-3 is embedded in the center of the right side of the gas cell body 4-4. The centers of the MEMS infrared light source 4-2 and the infrared detector 4-3 are at the same horizontal level. Both the MEMS infrared light source 4-2 and the infrared detector 4-3 have interface circuits at their tail ends, and the relevant pins are connected to the control and processing module 6.

[0060] As a preferred embodiment, a cylindrical gas pool 4-5 is formed at the center of the gas pool body 4-4. In other embodiments, a reflector or concave mirror can also be added to the gas pool 4-5 to increase the optical path.

[0061] As a preferred embodiment, the photoacoustic cell body 5-7 has a second gas exchange membrane 5-1 bonded at the threaded hole connection to facilitate gas entry and exit; the photoacoustic cell body 5-7 is made of metal, including but not limited to brass and stainless steel, and the cell body is thick enough to achieve the effect of shock absorption and isolation of external noise.

[0062] A MEMS infrared laser 5-2, with wavelengths including but not limited to 1567nm and 4.67μm, is embedded in the center of the right side of the photoacoustic cell 5-7 to excite carbon monoxide gas and generate a photoacoustic signal. A high-reflectivity window 5-3 is fixed to the center of the left side of the photoacoustic cell 5-7 via a cover plate 5-4 to increase the optical path and improve detection sensitivity. The centers of the high-reflectivity window 5-3 and the MEMS infrared laser 5-2 are at the same horizontal level.

[0063] Those skilled in the relevant field should understand that Figure 2 The high-reflectivity window shown is only an example. In some other embodiments, the high-reflectivity window and cover plate can be removed, leaving the complete pool body on the left.

[0064] Furthermore, a first MEMS microphone 5-5 is embedded in the top center of the photoacoustic cell 5-7, and a second MEMS microphone 5-6 is embedded in the rear center. The first MEMS microphone 5-5 and the second MEMS microphone 5-6 form a spatial array. The second gas exchange membrane 5-1 is not on the same vertical line as the first MEMS microphone 5-5 to avoid gas noise affecting the photoacoustic spectrum detection effect, thereby reducing the influence of gas flow on the photoacoustic signal received by the MEMS microphone 5-5. The MEMS infrared laser 5-2, the first MEMS microphone 5-5, and the second MEMS microphone 5-6 all have interface circuits at their tail ends, and the relevant pins are connected to the control processing module 6.

[0065] As a preferred embodiment, a cylindrical photoacoustic cell 5-8 is formed in the center of the photoacoustic cell body 5-7, with a smooth surface, which can be plated with gold or silver if necessary.

[0066] Those skilled in the relevant field should understand that Figure 2 The cylindrical photoacoustic cell shown is only an example; the actual photoacoustic cell structure can also be spherical, Helmholtz resonator, etc.

[0067] Please refer to Figure 3 The control and processing module 6 mainly includes a laser control circuit 6-1, a photoacoustic signal preprocessing circuit 6-2, a lock-in amplifier circuit 6-3, and a central processing circuit 6-4. The laser control circuit 6-1 includes a laser modulation circuit 6-1-1 and a laser temperature control circuit 6-1-2. The laser modulation circuit 6-1-1 can generate sinusoidal modulation signals and sawtooth or triangular wave signals to modulate the MEMS infrared light source 4-2 and the MEMS infrared laser 5-2.

[0068] Furthermore, the sinusoidal modulation signal frequency f is designed based on the resonant frequency of the photoacoustic cell 5-8. This is because the sinusoidal modulation signal frequency has a greater impact on the carbon monoxide sensor based on photoacoustic spectroscopy, but a smaller impact on the methane sensor based on absorption spectroscopy. Therefore, in this embodiment, a single DDS chip is sufficient to generate the sinusoidal modulation signal in the laser modulation circuit.

[0069] The laser temperature control circuit 6-1-2 regulates the temperature of the MEMS infrared light source 4-2 and the MEMS infrared laser 5-2, respectively.

[0070] The photoacoustic signal preprocessing circuit 6-2 performs time delay processing on the photoacoustic signal received by the second MEMS microphone 5-6, and then performs addition, subtraction, time-frequency decomposition and other operations with the photoacoustic signal received by the first MEMS microphone 5-5 to obtain the target photoacoustic signal, so as to further reduce the strong noise interference in the downhole environment and the noise interference in the photoacoustic cell, and improve the detection limit of trace carbon monoxide.

[0071] The lock-in amplifier circuit 6-3 receives the signal from the infrared detector 4-3 and the photoacoustic signal processed by the photoacoustic signal preprocessing circuit 6-2, and locks and amplifies its second harmonic (2f) signal.

[0072] The central processing circuit 6-4 is used to acquire and process the second harmonic signal, and to store and transmit the gas concentration results obtained from the processing.

[0073] Please refer to Figure 1 As a preferred embodiment, the control processing module 6 is also connected to the display module 7, the wireless transmission module 8, and the wired transmission module 9 to display and transmit the methane and carbon monoxide concentration detection results.

[0074] The wireless transmission module 8 can communicate via methods including but not limited to Wi-Fi and LoRa, and can upload gas concentration detection results to higher-level devices, such as underground signal acquisition substations and surface monitoring platforms. The specific implementation method is set according to the mine environment and surface requirements.

[0075] The wired transmission module 9 can communicate via methods including but not limited to RS485 and optical fiber, and can upload gas concentration detection results to higher-level equipment, such as underground signal acquisition substations and surface monitoring platforms. The specific implementation method is set according to the mine environment and surface requirements.

[0076] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A full-laser methane and carbon monoxide detection device for borehole extraction, characterized in that, include: The system comprises a connecting pipe (1), a gas buffer pool (3) connected to one end of the connecting pipe, a methane sensor assembly (4), a carbon monoxide sensor assembly (5), a control processing module (6), a transmission module, and a power supply module (10). The methane sensor assembly (4) and the carbon monoxide sensor assembly (5) are fixedly arranged side by side on the top of the cavity structure gas buffer pool (3) and the gas to be detected is supplied to them by the gas buffer pool through a gas exchange membrane. The control processing module (6) is connected to the methane sensor assembly (4), the carbon monoxide sensor assembly (5), the transmission module, and the power supply module (10). The methane sensor assembly (4) includes a cavity structure gas pool body (4-4). MEMS infrared light source (4-2) and infrared detector (4-3) with the same center height are embedded in the center of the cavity wall on the left and right sides of the gas pool body (4-4). The carbon monoxide sensor assembly (5) includes a photoacoustic cell (5-7) with a cavity structure; a first MEMS microphone (5-5) is embedded in the center of the top of the photoacoustic cell (5-7), and a second MEMS microphone (5-6) is embedded in the center of the rear side; the first MEMS microphone (5-5) and the second MEMS microphone (5-6) form a spatial array; the gas exchange membrane (5-1) at the connection between the photoacoustic cell (5-7) and the gas buffer pool (3) is offset from the first MEMS microphone (5-5) in the horizontal direction; a MEMS infrared laser (5-2) is embedded in the center of the right side of the photoacoustic cell (5-7); the sinusoidal modulation signal frequencies of the MEMS infrared light source (4-2) and the MEMS infrared laser (5-2) are consistent; The control processing module (6) includes a photoacoustic signal preprocessing circuit (6-2). The photoacoustic signal preprocessing circuit (6-2) performs time delay processing on the photoacoustic signal received by the second MEMS microphone (5-6), and then performs addition, subtraction and time-frequency decomposition operations on the photoacoustic signal received by the first MEMS microphone (5-5) to obtain the target photoacoustic signal. A reflector and a concave mirror are added to the gas pool (4-5) to increase the optical path.

2. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 1, characterized in that, The MEMS infrared laser (5-2), the first MEMS microphone (5-5), the second MEMS microphone (5-6), the MEMS infrared light source (4-2), and the infrared detector (4-3) all have interface circuits at their tail ends, and the relevant pins are connected to the control processing module (6).

3. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 1, characterized in that, The high reflectivity window (5-3) is fixed to the center of the left side of the photoacoustic cell body (5-7) by a cover plate (5-4) to increase the optical path and improve the detection sensitivity; the center of the high reflectivity window (5-3) and the MEMS infrared laser (5-2) are at the same horizontal height.

4. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 1, characterized in that, A first through channel structure (12) is provided at the connection between the gas pool body (4-4) and the gas buffer pool (3); a first gas exchange membrane (4-1) is provided in the first through channel structure (12), and the gas in the gas buffer pool (3) can enter the gas pool (4-5) through the first gas exchange membrane (4-1); a second through channel structure (13) is provided at the connection between the photoacoustic pool body (5-7) and the gas buffer pool (3), and a second gas exchange membrane (5-1) is provided in the second through channel structure (13), and the gas in the gas buffer pool (3) can enter the photoacoustic pool (5-8) through the second gas exchange membrane (5-1).

5. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 1, characterized in that, It also includes a water dust filter (2) installed on the connecting pipe (1).

6. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 1, characterized in that, The gas buffer pool (3) has a central opening at the bottom, which is connected to the connecting pipe (1); the bottom of the gas buffer pool (3) is inclined downward toward the central opening.

7. The all-laser methane and carbon monoxide detection device for borehole extraction according to any one of claims 1-6, characterized in that, The control processing module (6) includes a laser control circuit (6-1), a photoacoustic signal preprocessing circuit (6-2), a lock-in amplifier circuit (6-3), and a central processing circuit (6-4); the laser control circuit (6-1) includes a laser modulation circuit (6-1-1) and a laser temperature control circuit (6-1-2). The laser modulation circuit (6-1-1) can generate sinusoidal modulation signals and sawtooth or triangular wave signals to modulate the MEMS infrared light source (4-2) and the MEMS infrared laser (5-2); The laser temperature control circuit (6-1-2) regulates the temperature of the MEMS infrared light source (4-2) and the MEMS infrared laser (5-2) respectively; The photoacoustic signal preprocessing circuit (6-2) performs time delay processing on the photoacoustic signal received by the second MEMS microphone (5-6), and then performs addition, subtraction and time-frequency decomposition operations on the photoacoustic signal received by the first MEMS microphone (5-5) to obtain the target photoacoustic signal, so as to further reduce the strong noise interference in the downhole environment and the noise interference in the photoacoustic cell, and improve the detection limit of trace carbon monoxide. The lock-in amplifier circuit (6-3) receives the signal from the infrared detector (4-3) and the photoacoustic signal processed by the photoacoustic signal preprocessing circuit (6-2), locks in and amplifies its second harmonic (2f) signal; The central processing circuit (6-4) is used to acquire and process the second harmonic signal, and to store and transmit the gas concentration results obtained from the processing.

8. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 7, characterized in that, The sinusoidal modulation signal frequency is designed based on the resonant frequency of the photoacoustic cell (5-8). This is because the sinusoidal modulation signal frequency has a greater impact on the carbon monoxide sensor based on the photoacoustic spectroscopy principle, but a smaller impact on the methane sensor based on the absorption spectroscopy principle. Therefore, a DDS chip is used in the laser modulation circuit to generate the sinusoidal modulation signal.

9. The all-laser methane and carbon monoxide detection device for borehole extraction according to claim 7, characterized in that, The MEMS infrared laser (5-2) emits laser wavelengths including but not limited to 1567nm and 4.67μm to excite carbon monoxide gas to generate photoacoustic signals; the MEMS infrared light source (4-2) has wavelengths including but not limited to 1653nm and 3.4μm.

10. The detection method of the all-laser methane and carbon monoxide detection device for borehole extraction according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1: Preparation Ensure that all components, including the connecting pipe (1), water dust filter (2), gas buffer tank (3), methane sensor (4), carbon monoxide sensor (5), control processing module (6), display module (7), wireless transmission module (8), wired transmission module (9), and power supply module (10), are correctly installed and connected; provide power to the device through the power supply module (10) to ensure normal device startup; calibrate the methane sensor (4) and carbon monoxide sensor (5) as needed to ensure detection accuracy; Step 2: Connect the extraction pipeline Connecting pipes: Connect one end of the connecting pipe (1) to the extraction pipe in the coal mine, ensuring a tight connection without leakage; Check for airtightness: Confirm that the connection of the connecting pipe (1) is well sealed to prevent gas leakage from affecting the test results; Step 3: Start the detection device Turn on the device power and start the laser control circuit and photoacoustic signal preprocessing circuit in the control processing module (6); perform initial settings through the display module (7), including detection parameters and transmission mode; Step 4: Gas extraction and filtration The downhole gas is transported to the detection device through the extraction pipeline; the gas first passes through the water dust filter (2) to remove moisture and impurities and prevent damage to the sensor; Step 5: Gas Detection Methane detection: Gas enters the methane sensor (4) through the gas buffer pool (3); the MEMS infrared light source (4-2) excites the methane gas, and the infrared detector (4-3) detects the generated spectral signal; the control processing module (6) processes the signal and calculates the methane concentration; Carbon monoxide detection: Gas enters carbon monoxide sensor (5) through gas buffer pool (3); MEMS infrared laser (5-2) excites carbon monoxide gas to generate photoacoustic signal; first MEMS microphone (5-5) and second MEMS microphone (5-6) receive photoacoustic signal, control processing module (6) to process signal and calculate carbon monoxide concentration; Step Six: Data Processing and Display The central processing circuit of the control processing module (6) collects and processes signals from the methane sensor (4) and the carbon monoxide sensor (5) to calculate the gas concentration; the processing results are displayed through the display module (7), including the real-time concentrations of methane and carbon monoxide.

Images