Photoacoustic spectrometry gas detection method, device and equipment and storage medium

Abstract

The invention provides a photoacoustic spectrometry gas detection method, device and equipment and a storage medium. According to the method, a T-shaped photoacoustic cell is utilized, and components such as a gas valve, a transparent window, an MEMS microphone and an optical fiber collimator are arranged. After to-be-detected gas is filled through the gas valve, noise with flat frequency response is introduced, and the MEMS microphone is used for collecting resonant frequency. The control circuit sets the modulation frequency of the distributed feedback laser to be half of the resonant frequency, then the air valve is closed, and the laser outputs modulated light to excite photoacoustic signals. The MEMS microphone obtains signals and converts the signals into electric signals, the electric signals are converted into digital signals through the control circuit, and the digital signals are transmitted to the computing device to be processed to obtain gas concentration values. According to the method, the resonance frequency is determined by utilizing the resonance amplification effect, and the laser modulation frequency is set, so that the influence of external environment change on the stability of a detection system is effectively reduced, and the stability of photoacoustic spectrometry gas detection is improved.

Description

Technical Field

[0001] The present application belongs to the field of gas detection, and in particular, relates to a photoacoustic spectroscopy gas detection method, device, equipment and storage medium. Background Art

[0002] As the foundation of DC power transmission, the operation, maintenance and fault prevention measures of HVDC converter stations are crucial for stable power transmission. At present, in order to solve the problems of short circuit and discharge inside the converter station, the online oil chromatography technology is mainly used to monitor and analyze the dissolved gas in the oil caused by the fault inside the equipment. In the long-term operation, the insulating oil will decompose and produce a variety of characteristic gases due to faults such as overheating and discharge, most of which are dissolved in the oil. By analyzing the composition and content of the dissolved gas in the oil, the type and severity of the latent insulation fault inside the converter station equipment can be determined. Therefore, the real-time monitoring of the dissolved gas in the oil is of great significance to the reliable operation of the power grid.

[0003] However, traditional gas chromatographs require frequent calibration and maintenance, and the operation is cumbersome, which increases the workload of converter station maintenance. Photoacoustic spectroscopy gas detection technology has the advantages of simple operation, high sensitivity, high selectivity and fast response speed, and it is playing an increasingly important role in the field of dissolved gas analysis (DGA) in oil. However, the existing photoacoustic spectroscopy gas detection system has the problem that its stability is affected by the properties of the gas to be measured. When the properties of the gas to be measured, such as temperature, air pressure or humidity, change, the resonant frequency of the photoacoustic cell will also change, resulting in a large deviation between the detected value and the actual value. Summary of the invention

[0004] The purpose of the present application is to overcome the above-mentioned prior art and provide a photoacoustic spectroscopy gas detection method, device, equipment and storage medium.

[0005] The present application provides a photoacoustic spectroscopy gas detection method, comprising:

[0006] A first air valve is arranged on the side of the head of the T-shaped photoacoustic cell, a transparent window is arranged on the top of the head, a second air valve is arranged on the side of the tail, and a MEMS microphone and a fiber collimator are arranged on the bottom of the tail;

[0007] Connecting the fiber collimator to a distributed feedback laser via an optical fiber; connecting the distributed feedback laser to a control circuit; and connecting the control circuit to a computing device;

[0008] Open the first gas valve and the second gas valve to fill the T-shaped photoacoustic cell with the gas to be tested, and after the filling is completed, close the second gas valve;

[0009] The noise with a flat frequency response to be measured enters the T-type photoacoustic cell through the first air valve;

[0010] The MEMS microphone collects the resonance frequency of the noise entering the T-shaped photoacoustic cell;

[0011] The control circuit turns on the distributed feedback laser and sets the modulation frequency of the distributed feedback laser to half of the resonance frequency;

[0012] The first gas valve is closed, and the modulated light output by the distributed feedback laser is incident on the T-type photoacoustic cell through the fiber collimator, and the photoacoustic signal is excited and emitted from the window piece;

[0013] The MEMS microphone acquires the excitation photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit;

[0014] The control circuit converts the electrical signal into a digital signal and sends the digital signal to the computing device for processing to obtain the concentration value of the gas to be measured.

[0015] Optionally, the MEMS microphone collects the resonance frequency of the noise entering the T-shaped photoacoustic cell, including:

[0016] The computing device performs a frequency scan of the fundamental frequency of the acoustic signal collected by the MEMS microphone through the control circuit;

[0017] The frequency spectrum obtained by scanning is subjected to Gaussian fitting within a preset range of the first resonance frequency of the frequency spectrum to obtain the resonance frequency.

[0018] Optionally, the transparent window is made of calcium fluoride glass with enhanced infrared transmittance.

[0019] Optionally, the optical fiber collimator is a single-mode optical fiber collimator with a central wavelength of 1550 nm and a working distance of 80 mm.

[0020] Optionally, the inner diameter of the resonance tube of the T-type photoacoustic cell is 6 mm, the length is 40 mm, the inner diameter of the buffer chamber is 30 mm, the length is 40 mm, and the material is aluminum alloy.

[0021] Optionally, both the first gas valve and the second gas valve are solenoid valves, and their opening and closing are controlled by the control circuit.

[0022] Optionally, the central wavelength of the distributed feedback laser is 1532.8 nm, corresponding to the absorption peak of acetylene.

[0023] The present application also provides a photoacoustic spectroscopy gas detection device, comprising: a T-shaped photoacoustic cell, a first gas valve, a second gas valve, a transparent window, a MEMS microphone, a fiber collimator, a distributed feedback laser, a control circuit and a computing device;

[0024] The T-shaped photoacoustic cell has a first air valve disposed on the side of the head, a transparent window disposed on the top of the head, a second air valve disposed on the side of the tail, and a MEMS microphone and a fiber collimator disposed on the bottom of the tail;

[0025] The fiber collimator is connected to a distributed feedback laser via an optical fiber; the distributed feedback laser is connected to a control circuit; and the control circuit is connected to a computing device;

[0026] The MEMS microphone, the first air valve and the second air valve are connected to the control circuit;

[0027] The computing device controls the opening and closing of the first gas valve and the second gas valve, the MEMS microphone collects light and sound, and the distributed feedback laser emits laser through the control circuit;

[0028] The computing device is used to obtain the photoacoustic data collected by the MEMS microphone and perform photoacoustic spectroscopy gas analysis.

[0029] The present application also provides a photoacoustic spectroscopy gas detection device, comprising:

[0030] Memory;

[0031] The processor is used to retrieve the computing device executable program of the above-mentioned photoacoustic spectroscopy gas detection method from the memory, and execute: opening the first gas valve and the second gas valve to fill the T-type photoacoustic cell with the gas to be measured, and closing the second gas valve after the filling is completed; the noise with a flat frequency response to be measured enters the T-type photoacoustic cell through the first gas valve; the MEMS microphone collects the resonant frequency of the noise entering the T-type photoacoustic cell; the control circuit turns on the distributed feedback laser and sets the modulation frequency of the distributed feedback laser to half of the resonant frequency; closing the first gas valve, the distributed feedback laser outputs modulated light to enter the T-type photoacoustic cell through the fiber collimator, excites the photoacoustic signal and emits it from the window piece; the MEMS microphone obtains the excitation photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit; the control circuit converts the electrical signal into a digital signal and sends it to the computing device for processing to obtain the concentration value of the gas to be measured.

[0032] The present application also provides a storage medium, comprising: storing a computing device executable program, the computing device executable program is used to be called by a processor to execute the steps of the above-mentioned photoacoustic spectroscopy gas detection method.

[0033] The beneficial effects of this application are:

[0034] The present application provides a photoacoustic spectroscopy gas detection method, comprising: arranging a first gas valve on the side of the head of a T-shaped photoacoustic cell, arranging a transparent window on the top of the head, arranging a second gas valve on the side of the tail, and arranging a MEMS microphone and a fiber collimator on the bottom of the tail; connecting the fiber collimator to a distributed feedback laser through an optical fiber; connecting the distributed feedback laser to a control circuit; connecting the control circuit to a computing device; opening the first gas valve and the second gas valve to fill the T-shaped photoacoustic cell with a gas to be tested, and closing the second gas valve after the gas filling is completed; passing the noise with a flat frequency response to be tested into the T-shaped photoacoustic cell through the first gas valve; and the MEMS microphone and the fiber collimator are connected to the fiber collimator to connect the distributed feedback laser to the control circuit; connecting the control circuit to a computing device; opening the first gas valve and the second gas valve to fill the T-shaped photoacoustic cell with a gas to be tested, and closing the second gas valve after the gas filling is completed; passing the noise with a flat frequency response to be tested into the T-shaped photoacoustic cell through the first gas valve; and The EMS microphone collects the resonant frequency of the noise entering the T-type photoacoustic pool; the control circuit turns on the distributed feedback laser and sets the modulation frequency of the distributed feedback laser to half of the resonant frequency; the first gas valve is closed, and the modulated light output by the distributed feedback laser is incident on the T-type photoacoustic pool through the fiber collimator, exciting the photoacoustic signal and emitting from the window piece; the MEMS microphone obtains the exciting photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit; the control circuit converts the electrical signal into a digital signal and sends it to the computing device for processing to obtain the concentration value of the gas to be measured. This application uses the resonance amplification effect to determine the resonant frequency of the photoacoustic pool under the current gas conditions, and then sets the modulation frequency of the distributed feedback laser according to this resonant frequency, thereby effectively reducing the influence of the resonant frequency drift caused by changes in the external environment on the stability of the detection system and improving the stability of photoacoustic spectroscopy gas detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the photoacoustic spectroscopy gas detection process in this application;

[0036] Figure 2 This is a schematic diagram of photoacoustic spectroscopy gas detection in this application. DETAILED DESCRIPTION

[0037] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided in order to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0038] Please refer to Figure 1 and Figure 2 As shown, the present application provides a photoacoustic spectroscopy gas detection method, which is implemented based on a novel photoacoustic spectroscopy gas detection device of the present application.

[0039] The photoacoustic spectroscopy gas detection device comprises:

[0040] T-type photoacoustic cell 5;

[0041] The first gas valve 8 is arranged at the side of the head of the T-shaped photoacoustic cell 5, and its main function is to control the inflow of the gas to be tested. When the gas needs to be tested, the first gas valve 8 is opened to allow the gas to be tested to enter the T-shaped photoacoustic cell 5.

[0042] A transparent window (window sheet 6) is provided on the top of the T-shaped photoacoustic cell 5: it is used for the modulated light emitted by the distributed feedback laser 3 to pass through and irradiate the gas inside the photoacoustic cell 5. At the same time, the photoacoustic signal will also be transmitted through the transparent window and collected by the subsequent MEMS microphone 7.

[0043] The second gas valve 9 is arranged at the side of the tail of the T-shaped photoacoustic cell 5, and its function is to adjust the gas pressure in the photoacoustic cell 5 or discharge the waste gas. During the detection process, the second gas valve 9 may remain closed to ensure that the gas in the photoacoustic cell 5 is stable.

[0044] A MEMS microphone 7 and a fiber collimator 4 are arranged at the lower end of the T-shaped photoacoustic cell 5. The MEMS microphone 7 is used to collect photoacoustic signals and convert them into electrical signals for subsequent processing. The fiber collimator 4 is arranged next to the MEMS microphone 7 and is responsible for collimating the modulated light emitted by the distributed feedback laser 3 to ensure that the light can accurately irradiate the inside of the T-shaped photoacoustic cell 5.

[0045] The fiber collimator 4 is connected to the distributed feedback laser 3 via an optical fiber. The modulated light emitted by the laser is transmitted to the fiber collimator 4 via the optical fiber, and then the fiber collimator 4 accurately irradiates the light into the interior of the T-shaped photoacoustic cell 5.

[0046] The distributed feedback laser 3 is connected to the control circuit 2, and the control circuit 2 is responsible for sending a modulation signal to the laser to control the output frequency and intensity of the laser.

[0047] The control circuit 2 is also connected to the computing device 1 (such as a computing device) via a data line or a communication protocol. The control circuit 2 preliminarily processes the electrical signal collected by the MEMS microphone 7, converts it into a digital signal, and then sends it to the computing device 1 for further analysis and processing.

[0048] S101 , opening the first gas valve 8 and the second gas valve 9 to fill the T-shaped photoacoustic cell 5 with the gas to be tested, and closing the second gas valve 9 after the filling is completed.

[0049] The computing device 1 sends an instruction to the control circuit 2. After receiving the instruction, the control circuit 2 controls the opening of the first gas valve 8 and the second gas valve 9 to allow the gas to be measured to enter the T-type photoacoustic cell 5.

[0050] After the T-shaped photoacoustic cell 5 is filled with the gas to be measured, the control circuit 2 closes the second gas valve 9 again according to the instruction of the computing device 1, while the first gas valve 8 remains open.

[0051] T-type photoacoustic cell 5 parameters:

[0052] Resonance tube: Inner diameter: 6mm Length: 40mm

[0053] Buffer chamber: Inner diameter: 30mm Length: 40mm

[0054] Material: Aluminum alloy, which helps to reduce interference from the external environment and improve the stability of the system.

[0055] Window 6: It is made of infrared transmittance-enhanced calcium fluoride glass. This material has excellent light transmittance and can ensure that the laser can smoothly enter the T-type photoacoustic cell 5 and stimulate the photoacoustic signal.

[0056] The control circuit 2 is based on the FPGA phase-locked amplifier circuit, which provides high-precision signal amplification and processing capabilities. The functions include: 1. Providing control signals for the first gas valve 8 and the second gas valve 9 to ensure that the filling and discharge of gas can be carried out according to the predetermined program. 2. Providing a modulation signal to the distributed feedback laser 3 for the control circuit 2 to control the intensity and frequency of the laser, thereby exciting the photoacoustic signal in the gas to be measured.

[0057] S102 , the noise with a flat frequency response to be measured enters the T-shaped photoacoustic cell 5 through the first air valve 8 .

[0058] If the first air valve 8 is not closed, the noise in the converter station will follow the preset path and enter the T-type photoacoustic cell 5 through the air valve 1. These noises have the characteristic of flat frequency response, which means that their energy distribution at each frequency is relatively uniform, which provides a basis for the subsequent determination of the resonance frequency.

[0059] After the noise enters the T-type photoacoustic cell 5, it undergoes a resonance amplification process.

[0060] The design of the T-type photoacoustic cell 5 has a specific resonant frequency. When the frequency of the noise matches the resonant frequency of the T-type photoacoustic cell 5, the noise will be resonantly amplified in the photoacoustic cell 5. This effect significantly enhances the energy of the noise near the resonant frequency.

[0061] The system can determine the current resonance frequency by monitoring the resonance amplification of the noise in the T-type photoacoustic cell 5. This step is the key to subsequently adjusting the laser modulation frequency and improving the stability of the detection system.

[0062] S103 , the MEMS microphone 7 collects the resonance frequency of the noise entering the T-shaped photoacoustic cell 5 .

[0063] In the T-type photoacoustic cell 5, noise with a flat frequency response inside the converter station is introduced and resonantly amplified.

[0064] The MEMS microphone 7 (located in the T-shaped photoacoustic cell 5 ) is responsible for collecting the resonantly amplified acoustic signals, especially the resonant frequency portion thereof.

[0065] The computing device 1 sends instructions to the MEMS microphone 7 through the control circuit 2, requiring it to perform a frequency scan of the fundamental frequency of the collected acoustic signal, in order to obtain the complete frequency response of the T-type photoacoustic cell 5 under the current gas conditions, especially to determine its resonant frequency.

[0066] The computing device 1 receives the acoustic signal data collected and transmitted back by the MEMS microphone 7, processes and analyzes the data. In the scanned frequency spectrum, the computing device 1 searches for the first resonant frequency and performs Gaussian fitting near the first resonant frequency.

[0067] Gaussian fitting is a mathematical method used to reduce the error in the resonance frequency measurement and improve the accuracy of the measurement. Through Gaussian fitting, the computing device 1 can determine the resonance frequency of the T-type photoacoustic cell 5 more accurately.

[0068] S104 , the control circuit 2 turns on the distributed feedback laser 3 , and sets the modulation frequency of the distributed feedback laser 3 to half of the resonance frequency.

[0069] The computing device 1 sends instructions to the distributed feedback laser 3 through the control circuit 2 to start the operation.

[0070] The control circuit 2 calculates a value of half of the resonance frequency obtained by Gaussian fitting, and sets this value as the modulation frequency of the distributed feedback laser 3 to reduce the error caused by resonance frequency drift due to changes in the external environment (such as temperature, air pressure or humidity changes).

[0071] Preferably, the central wavelength of the distributed feedback laser 3 is 1532.8 nm, which corresponds to the absorption peak of acetylene, so that the system can efficiently detect acetylene gas. Fiber collimator 4: a single-mode fiber collimator 4 with a central wavelength of 1550 nm (close to the central wavelength of the laser) and a working distance of 80 mm. The fiber collimator 4 is installed along the longitudinal direction of the T-type photoacoustic cell 5 and is directly opposite to the window 6 at the end of the buffer chamber of the T-type photoacoustic cell 5. This design ensures that the modulated light can be accurately incident on the T-type photoacoustic cell 5 and effectively excite the photoacoustic signal.

[0072] By accurately setting the modulation frequency of the distributed feedback laser 3 to half of the resonance frequency, the system can reduce the error caused by the resonance frequency drift, thereby improving the stability of the photoacoustic spectroscopy gas detection system. In addition, this design also uses the noise with a flat frequency distribution inside the converter station as an external source signal, and determines the current resonance frequency through the resonance amplification effect of the T-type photoacoustic cell 5, without the need for additional calibration equipment or operations, further simplifying the operation process and reducing maintenance costs.

[0073] S105 , closing the first gas valve 8 , the modulated light output by the distributed feedback laser 3 enters the T-type photoacoustic cell 5 through the fiber collimator 4 , excites the photoacoustic signal and emits from the window 6 .

[0074] The first air valve 8 is closed, and the end of the buffer chamber of the T-type photoacoustic cell 5 is closed, while the second air valve 9 at the end of the resonance tube has been closed. In this way, a relatively closed environment is formed in the T-type photoacoustic cell 5, which is conducive to the stable generation and detection of photoacoustic signals.

[0075] Subsequently, the modulated light output by the distributed feedback laser 3 is precisely guided and calibrated by the fiber collimator 4 and incident into the T-type photoacoustic cell 5. The frequency of the modulated light matches the current resonance frequency of the T-type photoacoustic cell 5 (because it is set to half of the resonance frequency, in the photoacoustic spectroscopy technology, a modulated light frequency twice the photoacoustic signal frequency is usually used to stimulate the photoacoustic effect, but the description here may be that the specific design or optimization of the system is considered, so half of the resonance frequency is directly used as the modulation frequency), so that it interacts with the gas to be measured inside the T-type photoacoustic cell 5 to stimulate the generation of photoacoustic signals.

[0076] The photoacoustic signal generated by the excitation will be emitted from the window 6 of the T-type photoacoustic cell 5. This window 6 is specially made to allow the effective propagation of the photoacoustic signal while preventing interference from external noise. Subsequently, the photoacoustic signal will be collected by the MEMS microphone 7 and converted into an electrical signal for subsequent processing and analysis.

[0077] S106 , the MEMS microphone 7 acquires the excitation photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit 2 .

[0078] The MEMS microphone 7 captures these excited photoacoustic signals and efficiently converts them into electrical signals. This conversion process ensures the accuracy and measurability of the photoacoustic signals. Subsequently, these electrical signals are quickly transmitted to the control circuit 2 for further processing and analysis.

[0079] S107: The control circuit 2 converts the electrical signal into a digital signal and sends it to the computing device 1 for processing to obtain the concentration value of the gas to be measured.

[0080] The control circuit 2 first amplifies and filters the received analog electrical signals to ensure the accuracy and stability of the signals. Subsequently, it converts these analog electrical signals into digital signals using an analog-to-digital converter (ADC). This digitization process is crucial for subsequent signal processing and calculations because it allows the computing device 1 to process these signals with higher accuracy and efficiency.

[0081] Once the electrical signals are converted into digital signals, they are sent to the computing device 1 for post-processing. Specially designed algorithms are running inside the computing device 1, which can analyze the characteristics of the digital signals such as frequency, amplitude and phase, so as to infer the concentration value of the gas to be measured. In this process, the computing device 1 may use the known gas absorption spectrum characteristics, the geometric parameters of the photoacoustic cell 5, and the modulation frequency of the laser to calculate the concentration of the gas through a complex mathematical model.

[0082] Finally, after post-processing by the computing device 1, the user can obtain the accurate concentration value of the gas to be measured. This result is of great significance for monitoring the type and severity of latent insulation faults inside the converter station equipment, and helps to ensure the reliable operation of the power grid.

[0083] Please refer to Figure 2 As shown, the present application also provides a photoacoustic spectroscopy gas detection device, which is a system integrating high-precision, high-sensitivity detection elements and advanced control technology, and is suitable for gas concentration monitoring in complex environments such as converter stations. The photoacoustic spectroscopy gas detection device comprises:

[0084] T-type photoacoustic cell 5:

[0085] The T-shaped photoacoustic cell 5 is the core component of the detection system and has a unique design. A first air valve 8 is provided on the side of the head to control the inflow of the gas to be tested; a transparent window is provided on the top of the head to allow the laser to penetrate and irradiate the inside of the photoacoustic cell 5; a second air valve 9 is provided on the side of the tail to adjust or discharge the gas in the photoacoustic cell 5; a MEMS microphone 7 and a fiber collimator 4 are integrated at the bottom of the tail, which are used for collecting sound signals and guiding the laser, respectively.

[0086] The T-type photoacoustic cell 5 utilizes laser to excite the gas to be detected to produce a photoacoustic effect, and improves the detection sensitivity through the resonance amplification effect.

[0087] The first gas valve 8 and the second gas valve 9 are respectively located at the head side and the tail side of the T-shaped photoacoustic cell 5. The first gas valve 8 is used to control the inflow of the gas to be measured, and the second gas valve 9 is used to adjust or discharge the gas in the photoacoustic cell 5, thereby realizing precise control of the gas environment inside the photoacoustic cell 5.

[0088] The transparent window is located on the top of the T-shaped photoacoustic cell 5. The transparent window allows the laser to penetrate and irradiate the inside of the photoacoustic cell 5, and is a key component for the interaction between the laser and the gas to be measured.

[0089] The MEMS microphone 7 is located at the lower end of the tail of the T-shaped photoacoustic cell 5. The MEMS microphone 7 has high sensitivity and can accurately collect the photoacoustic signal generated by laser excitation and convert it into an electrical signal for subsequent processing.

[0090] The fiber collimator 4 is also located at the lower end of the T-shaped photoacoustic cell 5, adjacent to the MEMS microphone 7. The fiber collimator 4 is used to guide the laser from the distributed feedback laser 3 to the inside of the T-shaped photoacoustic cell 5, ensuring that the laser can accurately irradiate the gas to be measured.

[0091] The distributed feedback laser 3 is connected to the fiber collimator 4 through an optical fiber. The distributed feedback laser 3 can emit stable and frequency-adjustable laser light to excite the gas to be measured to produce a photoacoustic effect. Its modulation frequency can be adjusted according to the resonance frequency of the T-type photoacoustic cell 5 to improve the stability of the detection system.

[0092] The control circuit 2 is respectively connected to the distributed feedback laser 3, the MEMS microphone 7, the first gas valve 8, the second gas valve 9, and the computing device 1. The control circuit 2 is responsible for receiving instructions from the computing device 1, controlling the opening and closing of the gas valve, the emission of the laser, and the collection of the MEMS microphone 7. At the same time, it also converts the electrical signal collected by the MEMS microphone 7 into a digital signal and sends it to the computing device 1 for subsequent processing.

[0093] The computing device 1 is connected to other components through the control circuit 2. The computing device 1 is the data processing center of the detection system, which is responsible for receiving the digital signal sent by the control circuit 2 and performing photoacoustic spectroscopy gas analysis to obtain the concentration value of the gas to be tested.

[0094] The computing device 1 controls the opening and closing of the first gas valve 8 and the second gas valve 9 through the control circuit 2 to fill the T-shaped photoacoustic cell 5 with the gas to be tested and discharge the gas when necessary.

[0095] The distributed feedback laser 3 emits laser light under the control of the control circuit 2 , and then irradiates the gas to be measured inside the T-shaped photoacoustic cell 5 after being guided by the optical fiber collimator 4 .

[0096] The laser excites the gas to be measured to produce a photoacoustic effect, and the MEMS microphone 7 collects the photoacoustic signal and converts it into an electrical signal.

[0097] The control circuit 2 converts the electrical signal collected by the MEMS microphone 7 into a digital signal and sends it to the computing device 1 for subsequent processing.

[0098] The computing device 1 performs photoacoustic spectroscopy gas analysis on the received digital signal and calculates the concentration value of the gas to be tested through a specific algorithm.

[0099] The photoacoustic spectroscopy gas detection device provided in the present application has the advantages of compact structure, high detection sensitivity, and easy operation, and is particularly suitable for gas concentration monitoring in complex environments such as converter stations.

[0100] The present application also provides a photoacoustic spectroscopy gas detection device, comprising:

[0101] Memory;

[0102] The processor is used to retrieve the computing device executable program of the above-mentioned photoacoustic spectroscopy gas detection method from the memory, and execute: opening the first gas valve 8 and the second gas valve 9 to fill the T-type photoacoustic cell 5 with the gas to be measured, and closing the second gas valve 9 after the filling is completed; the noise with a flat frequency response to be measured enters the T-type photoacoustic cell 5 through the first gas valve 8; the MEMS microphone 7 collects the resonance frequency of the noise entering the T-type photoacoustic cell 5; the control circuit 2 turns on the distributed feedback laser 3, and sets the modulation frequency of the distributed feedback laser 3 to half of the resonance frequency; closing the first gas valve 8, the distributed feedback laser 3 outputs modulated light to enter the T-type photoacoustic cell 5 through the fiber collimator 4, excites the photoacoustic signal and emits it from the window 6; the MEMS microphone 7 obtains the excitation photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit 2; the control circuit 2 converts the electrical signal into a digital signal and sends it to the computing device 1 for processing to obtain the concentration value of the gas to be measured.

[0103] The present application also provides a storage medium, comprising: storing a computing device executable program, the computing device executable program is used to be called by a processor to execute the steps of the above-mentioned photoacoustic spectroscopy gas detection method.

Claims

1. A photoacoustic spectroscopy gas detection method, characterized in that: include: A first air valve is arranged on the side of the head of the T-shaped photoacoustic cell, a transparent window is arranged on the top of the head, a second air valve is arranged on the side of the tail, and a MEMS microphone and a fiber collimator are arranged on the bottom of the tail; The fiber collimator is connected to a distributed feedback laser via an optical fiber; the distributed feedback laser is connected to a control circuit; and the control circuit is connected to a computing device; Open the first gas valve and the second gas valve to fill the T-shaped photoacoustic cell with the gas to be tested, and after the filling is completed, close the second gas valve; The noise with a flat frequency response to be measured enters the T-type photoacoustic cell through the first air valve; The MEMS microphone collects the resonance frequency of the noise entering the T-shaped photoacoustic cell; The control circuit turns on the distributed feedback laser and sets the modulation frequency of the distributed feedback laser to half of the resonance frequency; The first gas valve is closed, and the modulated light output by the distributed feedback laser is incident on the T-type photoacoustic cell through the fiber collimator to stimulate a photoacoustic signal, and the photoacoustic signal is emitted from the transparent window; The MEMS microphone acquires the photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit; The control circuit converts the electrical signal into a digital signal and sends the digital signal to the computing device for processing to obtain the concentration value of the gas to be measured.

2. A photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The MEMS microphone collects the resonance frequency of the noise entering the T-shaped photoacoustic cell, including: The computing device performs a frequency scan of the fundamental frequency of the acoustic signal collected by the MEMS microphone through the control circuit to obtain a frequency spectrum; Gaussian fitting is performed within a preset range of the first resonance frequency of the frequency spectrum to obtain the resonance frequency.

3. A photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The transparent window is made of calcium fluoride glass with enhanced infrared transmission.

4. The photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The optical fiber collimator is a single-mode optical fiber collimator with a central wavelength of 1550nm and a working distance of 80mm.

5. The photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The resonant tube of the T-type photoacoustic cell has an inner diameter of 6 mm and a length of 40 mm, and the buffer chamber has an inner diameter of 30 mm and a length of 40 mm, and is made of aluminum alloy.

6. The photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The first gas valve and the second gas valve are both solenoid valves, and their opening and closing are controlled by the control circuit.

7. The photoacoustic spectroscopy gas detection method according to claim 1, characterized in that: The central wavelength of the distributed feedback laser is 1532.8 nm.

8. A photoacoustic spectroscopy gas detection device, characterized in that: include: A T-type photoacoustic cell, a first gas valve, a second gas valve, a transparent window, a MEMS microphone, a fiber collimator, a distributed feedback laser, a control circuit and a computing device; The T-shaped photoacoustic cell has a first air valve disposed on the side of the head, a transparent window disposed on the top of the head, a second air valve disposed on the side of the tail, and a MEMS microphone and a fiber collimator disposed on the bottom of the tail; The fiber collimator is connected to a distributed feedback laser via an optical fiber; the distributed feedback laser is connected to a control circuit; and the control circuit is connected to a computing device; The MEMS microphone, the first air valve and the second air valve are connected to the control circuit; The computing device controls the opening and closing of the first gas valve and the second gas valve, the MEMS microphone collects light and sound, and the distributed feedback laser emits laser through the control circuit; The computing device is used to obtain the photoacoustic data collected by the MEMS microphone and perform photoacoustic spectroscopy gas analysis.

9. A photoacoustic spectroscopy gas detection device, characterized in that: include: Memory; A processor, configured to retrieve from the memory an executable program of a computing device for a photoacoustic spectroscopic gas detection method according to any one of claims 1 to 7, and execute: opening the first gas valve and the second gas valve to fill the T-shaped photoacoustic cell with a gas to be tested, and after the gas filling is completed, closing the second gas valve; passing the noise with a flat frequency response to be tested into the T-shaped photoacoustic cell through the first gas valve; The MEMS microphone collects the resonance frequency of the noise entering the T-type photoacoustic cell; the control circuit turns on the distributed feedback laser and sets the modulation frequency of the distributed feedback laser to half of the resonance frequency; the first gas valve is closed, and the modulated light output by the distributed feedback laser is incident on the T-type photoacoustic cell through the fiber collimator, excites the photoacoustic signal and is emitted from the window piece; the MEMS microphone obtains the excited photoacoustic signal, converts it into an electrical signal and transmits it to the control circuit; the control circuit converts the electrical signal into a digital signal and sends it to the computing device for processing to obtain the concentration value of the gas to be measured.

10. A storage medium, characterized in that: include: A computing device executable program is stored, and the computing device executable program is used to be called by a processor to execute the steps of a photoacoustic spectroscopy gas detection method as described in any one of claims 1 to 7.

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