Laser gas detection device and gas concentration detection method

Abstract

The invention provides a laser gas detection device and a gas concentration detection method. The laser gas detection device comprises a laser, a to-be-detected gas chamber and a photoelectric detector, the to-be-detected gas chamber is an internal optical-mechanical structure space of the laser gas detection device, and the photoelectric detector comprises a detector main body and a reference gas chamber; the to-be-detected gas chamber is used for loading to-be-detected gas; the laser is used for emitting laser and emitting the laser into the to-be-detected gas chamber; the reference gas chamber is used for allowing the laser emitted from the to-be-detected gas chamber to penetrate through; and the detector main body is used for detecting the laser which passes through the gas chamber to be detected and the reference gas chamber so as to obtain an electric signal of the gas to be detected. The gas concentration detection lower limit of the laser gas detection device can be reduced, and the performance of the laser gas detection device can be improved.

Description

Technical Field

[0001] The present application relates to the technical field of laser gas sensors, and in particular to a laser gas detection device and a gas concentration detection method. Background Art

[0002] TDLAS (Tunable Diode Laser Absorption Spectroscopy) utilizes the current tunable characteristics of semiconductor lasers. The low-frequency periodic tuning current generated by the laser diode driver changes the narrow linewidth and wavelength of the laser output laser, so that the laser wavelength is periodically scanned within a fixed narrow linewidth range, and the scanned wavelength range covers the specific absorption wavelength of the target gas, thereby obtaining the concentration and other properties of the gas by analyzing the characteristic spectrum of the gas absorption laser.

[0003] By utilizing the relationship between light absorption intensity, gas concentration and gas length to satisfy the Lambert-Beer law, and detecting the change in absorption intensity after the gas interacts with light of a specific wavelength, accurate detection of specific gas concentrations can be achieved. The lower limit of gas concentration detection is of great significance for gas concentration detection. If low-concentration gases cannot be detected, a series of hazards may occur. For example, some harmful gases at low concentrations may also pose a threat to human health and production safety. If these low-concentration harmful gases cannot be accurately detected, harmful gas leaks may not be discovered in time, and the occupational health and production safety of on-site workers cannot be effectively protected.

[0004] However, the inventors of the present application discovered during the actual research and development process that when a laser gas detection device uses TDLAS technology to analyze gas concentration values, the gas concentration detection lower limit of the laser gas detection device is relatively high, making it difficult to detect the concentration value of low-concentration gases. Summary of the invention

[0005] The present application provides a laser gas detection device and a gas concentration detection method, which can reduce the gas concentration detection lower limit of the laser gas detection device and improve the performance of the laser gas detection device.

[0006] In a first aspect, the present application provides a laser gas detection device, the laser gas detection device comprising a laser, a gas chamber to be measured and a photoelectric detector, the gas chamber to be measured is the internal optical-mechanical structure space of the laser gas detection device, and the photoelectric detector comprises a detector body and a reference gas chamber;

[0007] The gas chamber to be tested is used to load the gas to be tested;

[0008] A laser, used for emitting laser light and injecting the laser light into the gas chamber to be tested;

[0009] A reference gas chamber, used to transmit the laser emitted from the gas chamber to be tested;

[0010] The detector body is used to detect the laser light passing through the gas chamber to be detected and the reference gas chamber to obtain the electrical signal of the gas to be detected.

[0011] In a second aspect, the present application provides a gas concentration detection method, the method comprising:

[0012] The laser of the laser gas detection device is used to emit laser light and the laser light is injected into a gas chamber to be detected which is loaded with the gas to be detected, wherein the laser gas detection device comprises a laser, a gas chamber to be detected and a photoelectric detector, the gas chamber to be detected is the internal optical-mechanical structure space of the laser gas detection device, and the photoelectric detector comprises a detector body and a reference gas chamber;

[0013] The detector body detects the laser light passing through the gas chamber to be detected and the reference gas chamber to obtain an electrical signal of the gas to be detected;

[0014] Obtaining an equivalent gas concentration value of the reference gas chamber;

[0015] An analysis is performed based on the equivalent gas concentration value and the electrical signal of the gas to be detected to obtain the actual detection concentration value of the gas to be detected.

[0016] In the present application, a laser gas detection device and a gas concentration detection method are provided. The laser gas detection device includes a laser, a gas chamber to be detected and a photoelectric detector, and the photoelectric detector includes a detector body and a reference gas chamber; the gas chamber to be detected is used to load the gas to be detected; the laser is used to emit laser and inject the laser into the gas chamber to be detected; the reference gas chamber is used to pass the laser emitted from the gas chamber to be detected; the detector body is used to detect the laser passing through the gas chamber to be detected and the reference gas chamber to obtain an electrical signal of the gas to be detected; in this way, by setting a reference gas chamber in the photoelectric detector, the gas in the reference gas chamber is used to absorb the laser passing through the gas chamber to be detected again, and the equivalent gas concentration value of the reference gas chamber can be used for compensation, so that the electrical signal detected by the photoelectric detector can detect the absorption peak, so that the absorption peak can still be detected when the concentration of the gas to be detected in the gas chamber to be detected is low, which solves the problem that the absorption peak cannot be detected at low concentration and the gas concentration value cannot be calculated, so that when the concentration of the gas to be detected is low, the actual concentration value of the gas to be detected can still be detected, the gas concentration detection lower limit of the laser gas detection device is reduced, and the performance of the laser gas detection device is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0018] Figure 1 is a structural schematic diagram of a laser gas detection device provided in an embodiment of the present application;

[0019] Figure 2 is a structural schematic diagram of the photoelectric detector 300 provided in an embodiment of the present application;

[0020] Figure 3 is another structural schematic diagram of the laser gas detection device provided in an embodiment of the present application;

[0021] Figure 4 is another structural schematic diagram of the laser gas detection device provided in the embodiments of the present application;

[0022] Figure 5 is another structural schematic diagram of the laser gas detection device provided in the embodiment of the present application;

[0023] Figure 6 It is a schematic diagram of a principle structure block of a laser gas detection device provided in an embodiment of the present application;

[0024] Figure 7 It is a flow chart of a gas concentration detection method provided in an embodiment of the present application;

[0025] Figure 8 It is a flow chart of the reference gas chamber 320 leakage detection and equivalent gas concentration value calibration provided in the embodiment of the present application;

[0026] Fig. 9 It is a schematic diagram comparing the changes in the gas electrical signal when there is a gas to be detected and when there is no gas to be detected in the test chamber 100 in the embodiment of the present application. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of this application.

[0028] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms "include", "comprises" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprises a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0029] The flow chart shown in the accompanying drawings is only an example, and does not necessarily include all the contents and operations / steps, nor does it have to be performed in the described order. For example, some operations / steps can also be decomposed, combined or partially merged, so the order of actual execution may change according to actual conditions. Any process or method description described in the flow chart or otherwise described herein can be understood to represent a module, fragment or part of a code of executable instructions including one or more steps for implementing a specific logical function or process. And the scope of the embodiments recorded in the present application includes other implementations, which may not be in the order shown or discussed, including performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, which should be understood by a technician in the technical field to which the embodiments of the present application belong.

[0030] In order to enable any person skilled in the art to implement and use the present application, the following description is provided. In the following description, details are listed for the purpose of explanation. It should be understood that those of ordinary skill in the art can recognize that the present application can also be implemented without using these specific details. In other examples, the known process will not be elaborated in detail to avoid unnecessary details that make the description of the present application embodiment obscure. Therefore, the present application is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in accordance with the embodiments of the present application.

[0031] This application embodiment provides a laser gas detection device, see Figure 1 and Figure 2 , Figure 1 is a schematic diagram of the structure of the laser gas detection device provided in the embodiment of the present application, Figure 2It is a structural schematic diagram of the photoelectric detector 300 provided in an embodiment of the present application. The laser gas detection device includes: a laser 100, a gas chamber to be tested 200 and a photoelectric detector 300. The gas chamber to be tested 200 is the internal optical-mechanical structure space of the laser gas detection device. The photoelectric detector 300 includes a detector body 310 and a reference gas chamber 320.

[0032] The gas chamber 100 to be tested is used to load the gas to be tested.

[0033] The laser 200 is used to emit laser light and inject the laser light into the gas chamber 100 to be tested.

[0034] The reference gas cell 300 is used to transmit the laser light emitted from the gas cell 100 to be tested.

[0035] The detector body 310 is used to detect the laser light passing through the gas chamber 100 to be detected and the reference gas chamber 320 to obtain the electrical signal of the gas to be detected.

[0036] For example, Figure 1 As shown, the laser 200 emits laser light I under the drive of the laser driver. o and injected into the gas chamber 100 to be tested, the laser I o After passing through the gas chamber 100 and being absorbed and attenuated by the gas to be detected, the laser I t The photodetector 300 receives the absorbed and attenuated laser light I t The laser then passes through the reference gas chamber 320, and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the detected laser into an electrical signal, thereby detecting the electrical signal of the gas to be detected. In this way, by setting the reference gas chamber 320 in the photodetector 300, the gas in the reference gas chamber 320 is used to absorb the laser passing through the gas chamber 100 to be detected again, and the equivalent gas concentration value of the reference gas chamber 320 can be used for compensation, so that the electrical signal detected by the photodetector 300 can detect the absorption peak, so that the absorption peak can still be detected when the concentration of the gas to be detected in the gas chamber 100 to be detected is low, which solves the problem that the absorption peak cannot be detected at low concentrations and the gas concentration value cannot be calculated, so that when the concentration of the gas to be detected is low, the actual concentration value of the gas to be detected can still be detected, thereby reducing the gas concentration detection lower limit of the laser gas detection device and improving the performance of the laser gas detection device.

[0037] In some embodiments, Figure 3 As shown, Figure 3It is another structural schematic diagram of the laser gas detection device provided in the embodiment of the present application. The laser gas detection device also includes an analog-to-digital converter 400 and a digital processing module 500. The analog-to-digital converter 400 and the digital processing module 500 are connected; the analog-to-digital converter 400 is used to convert the electrical signal of the gas to be detected into a digital signal; the digital signal is transmitted to the digital processing module 500, and the digital processing module 500 is used to collect the digital signal output by the analog-to-digital converter 400, and obtain the actual detection concentration value of the gas to be detected based on the digital signal analysis. The digital processing module 500 can detect the target absorption peak and baseline voltage value of the gas to be detected based on the digital signal; the preliminary detection concentration value of the gas chamber 100 to be detected can be calculated by substituting the ratio of the target absorption peak and the baseline voltage value into the corresponding functional relationship; the equivalent gas concentration value of the reference gas chamber is subtracted from the preliminary detection concentration value of the gas chamber 100 to obtain the actual detection concentration value of the gas to be detected; thus, by setting the reference gas chamber 320 on the photodetector 300, the laser can be attenuated more by the gas absorption effect in the reference gas chamber 320, thereby increasing the absorption peak value of the detected electrical signal, and then the absorption peak can still be detected when the concentration of the gas to be detected is low, reducing the detection lower limit of the gas concentration, and avoiding the problem that the gas concentration is difficult to detect due to the inability to detect the absorption peak when the concentration of the gas to be detected is low. The detailed implementation of the digital processing module 500 to detect the actual detection concentration value of the gas to be detected can refer to the relevant description of the gas concentration detection method embodiment below, and it will not be repeated here for the sake of simplicity.

[0038] In some embodiments, Figure 4 As shown, the laser gas detection device also includes an electric signal amplifying component 600, which is connected to the photodetector 300; the electric signal amplifying component 600 is used to receive the electric signal output by the detector body 310, and amplify the electric signal of the gas to be detected; the analog-to-digital converter 400 converts the amplified electric signal of the gas to be detected into a digital signal. Thus, the digital processing module 500 can detect the actual detection concentration value of the gas to be detected based on the digital signal. Thus, the electric signal amplifying component 600 is used to receive the electric signal output by the detector body 310, and amplify the electric signal of the gas to be detected. The weak electric signal can be amplified by the electric signal amplifying component 600, which is convenient for subsequent analysis and improves the gas detection accuracy.

[0039] In some embodiments, Figure 5As shown, the laser gas detection device may further include a low-pass filter 700, and the low-pass filter 700 is used to filter the electrical signal of the gas to be detected. In some embodiments, the laser gas detection device includes the low-pass filter 700 but does not include the electrical signal amplifying component 600. The low-pass filter 700 can directly receive the electrical signal output by the detector body 310 and directly filter the electrical signal output by the detector body 310. In some embodiments, the laser gas detection device includes both the low-pass filter 700 and the electrical signal amplifying component 600. The electrical signal amplifying component 600 is used to receive the electrical signal output by the detector body 310 and amplify the electrical signal of the gas to be detected. The low-pass filter 700 can receive the electrical signal amplified by the electrical signal amplifying component 600 and filter the electrical signal amplified by the electrical signal amplifying component 600. Therefore, by using the low-pass filter 700 to filter the electrical signal of the gas to be detected, low-frequency signals can be allowed to pass, attenuated or prevented from passing through high-frequency signals, thereby effectively using the TDLAS technology to analyze the gas concentration value and ensure the analysis accuracy of the gas concentration value.

[0040] In some embodiments, Figure 6 As shown, the laser gas detection device further includes a digital-to-analog converter 800 and a laser driver 900. The digital processing module 500 generates a digital signal through a signal generator. The digital-to-analog converter 800 is used to convert the digital signal generated by the signal generator of the digital processing module 500 into an analog signal. The laser driver 900 is used to receive the analog signal of the digital-to-analog converter 800 and generate a low-frequency periodic tuning current under the action of the analog signal. The laser 200 emits laser under the action of the current and injects the laser into the gas chamber 100 to be tested. Among them, the laser driver 900 can be a laser diode driver, an adjustable power laser driver, a frequency modulated laser driver, etc.

[0041] Please refer to Figure 6The working principle of the laser gas detection device is described below with a specific example. First, the digital processing module 500 generates a digital signal through a signal generator; then, the digital-to-analog converter 800 converts the digital signal generated by the signal generator of the digital processing module 500 into an analog signal; then, the laser driver 900 receives the analog signal of the digital-to-analog converter 800 and generates a low-frequency periodic tuning current under the action of the analog signal; then, the laser 200 emits a laser under the action of the low-frequency periodic tuning current and injects the laser into the gas chamber 100 to be detected; thereafter, the laser passes through the gas chamber 100 to be detected, is absorbed and attenuated by the gas to be detected, and then is transmitted out. The absorbed and attenuated laser is received by the photodetector 300, and the photodetector 300 receives the absorbed and attenuated laser. The laser then passes through the reference gas chamber 320 and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the detected laser into an electrical signal, thereby detecting the electrical signal of the gas to be detected; then, the electrical signal amplifying component 600 receives the electrical signal output by the detector body 310 and amplifies the electrical signal of the gas to be detected, and the low-pass filter 700 can receive the electrical signal amplified by the electrical signal amplifying component 600 and filter the electrical signal amplified by the electrical signal amplifying component 600; finally, the filtered electrical signal is converted into a digital signal by the analog-to-digital converter 400, and the digital processing module 500 can detect the actual detection concentration value of the gas to be detected based on the digital signal converted by the analog-to-digital converter 400.

[0042] See also Figure 6 and Figure 7 , Figure 7 701 to 704, wherein:

[0043] 701. The laser 200 of the laser gas detection device emits laser light and injects the laser light into the gas chamber 100 to be detected which is loaded with the gas to be detected.

[0044] The laser gas detection device includes a laser 200 , a gas chamber 100 to be tested and a photoelectric detector 300 . The gas chamber 100 to be tested is the internal optical-mechanical structure space of the laser gas detection device. The photoelectric detector 300 includes a detector body 310 and a reference gas chamber 320 .

[0045] For example, Figure 6As shown, first, the digital processing module 500 generates a digital signal through a signal generator; then, the digital-to-analog converter 800 converts the digital signal generated by the signal generator of the digital processing module 500 into an analog signal; then, the laser driver 900 receives the analog signal of the digital-to-analog converter 800 and generates a low-frequency periodic tuning current under the action of the analog signal; then, the laser 200 emits a laser under the action of the low-frequency periodic tuning current and injects the laser into the gas chamber 100 to be tested.

[0046] To better understand the gas concentration detection method, the basic structure and principle of the laser gas detection device are introduced below. Figure 6 and Fig. 9 , Fig. 9 1 is a schematic diagram comparing the changes in the gas electrical signal when there is a gas to be detected and when there is no gas to be detected in the gas chamber 100 to be detected in the embodiment of the present application. Figure 6 As shown, the laser gas detection device mainly includes two parts: an optical path part and a circuit. First, a digital signal is generated by the signal generator of the digital processing module 500, which is converted into an analog signal by the digital-to-analog converter 800 (the digital-to-analog converter 800 is used to convert the digital signal into an analog signal), and then the laser driver 900 (such as a laser diode driver) is driven to generate a low-frequency periodic tuning current. The current passes through the laser 200 to emit a tuned laser. The laser passes through the gas chamber 100 to be detected which is filled with the gas to be detected after being collimated. The incident light is absorbed and attenuated by the gas to be detected and is received by the photoelectric sensor 300, and the detected light signal is converted into an electrical signal. The weak electrical signal is then amplified by the amplification component 600 (such as an amplification circuit), and then filtered by the low-pass filter 700. Finally, the processor (the processor can be the digital processing module 500) is used to process and analyze the amplified and filtered electrical signal, detect the absorption peak of the gas, and finally calculate the concentration of the gas to be detected. The optical path part is interconnected with the external environment. When there is no gas to be detected in the external environment, the filtered electrical signal is as follows Fig. 9 As shown in (a), it is a periodic wedge-shaped wave; when there is a gas to be detected in the external environment, the filtered electrical signal is as follows Fig. 9 As shown in (b), a downward absorption peak is generated at a specific wavelength.

[0047] 702. Detect the laser light passing through the gas chamber to be detected 100 and the reference gas chamber 320 through the detector body 310 to obtain an electrical signal of the gas to be detected.

[0048] For example, Figure 6As shown, first, the laser passes through the gas chamber 100 to be detected and is absorbed and attenuated by the gas to be detected, and then passes out. The absorbed and attenuated laser is received by the photodetector 300; then, after the photodetector 300 receives the absorbed and attenuated laser, the laser passes through the reference gas chamber 320, and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the detected laser into an electrical signal, thereby detecting the electrical signal of the gas to be detected through the detector body 310.

[0049] 703 . Obtain an equivalent gas concentration value of the reference gas chamber 320 .

[0050] There are many ways to implement step 703, which include, for example:

[0051] (1) In some embodiments, the equivalent gas concentration value of the reference gas chamber 320 is calculated in real time. In this case, step 703 may specifically include: calculating the equivalent gas concentration value of the reference gas chamber 320 according to the gas chamber length L 1 , the optical path length L of the laser gas detection device 2 , the gas concentration value C in the reference gas chamber 320 1 The equivalent gas concentration value C of the reference gas chamber 320 is calculated by using the preset equivalent concentration calculation formula, and the preset equivalent concentration calculation formula is shown in the following formula 1:

[0052]

[0053] For example, taking the laser gas detection device as a point-type laser gas sensor, assuming that the internal optical path length of the point-type laser gas sensor is 10 cm (i.e., L 2 = 10 cm), the air chamber length of the reference air chamber 320 is 1 cm (ie L 1 = 1 cm), the gas concentration value of the package in the reference gas chamber 320 is set to 60% LEL (i.e. C 1 =60%LEL), then referring to Formula 1, the equivalent gas concentration value C=6%LEL of the reference gas chamber 320 can be calculated.

[0054] In this way, when it is necessary to make the gas equivalent concentration of the reference gas chamber 320 6%LEL, the packaged gas concentration value inside the reference gas chamber 320 can be set to 60%LEL. In this way, the packaged gas concentration value inside the reference gas chamber 320 can be dynamically adjusted according to actual needs to adapt to the detection concentration lower limit requirements of different gases to be detected.

[0055] (2) In some embodiments, the equivalent gas concentration value of the reference gas chamber 320 may be pre-calculated with reference to Formula 1 and stored in a database, and the equivalent gas concentration value of the reference gas chamber 320 may be directly read from the database in step 703 .

[0056] 704. Perform analysis based on the equivalent gas concentration value and the electrical signal of the gas to be detected to obtain an actual detection concentration value of the gas to be detected.

[0057] Exemplarily, step 704 may specifically include the following steps A1 to A3:

[0058] A1. Analyze and process the electrical signal of the gas to be detected to obtain the target absorption peak and baseline voltage value of the gas to be detected.

[0059] There are many ways to implement step A1, illustratively including the following ways ①, ②, and ③:

[0060] Method ①: In some embodiments, the electrical signal of the gas to be detected detected by the detector body 310 is directly analyzed. Figure 6 As shown, first, the laser passes through the gas chamber 100 to be detected and is absorbed and attenuated by the gas to be detected, and then is transmitted out. The absorbed and attenuated laser is received by the photodetector 300; then, the photodetector 300 receives the absorbed and attenuated laser, and then the laser passes through the reference gas chamber 320, and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the laser detected by the laser into an electrical signal, so that the electrical signal of the gas to be detected is detected by the detector body 310, and the electrical signal of the gas to be detected detected by the detector body 310 can be directly converted into a digital signal through the analog-to-digital converter 400, so as to obtain the digital signal of the gas to be detected. Then, the target absorption peak and baseline voltage value of the gas to be detected are obtained by analyzing the digital signal of the gas to be detected. Finally, the ratio of the target absorption peak and the baseline voltage value and the gas concentration are in a nonlinear functional relationship (a linear relationship at low concentrations). By obtaining the ratio of the target absorption peak and the baseline voltage value and substituting it into the corresponding functional relationship, the gas concentration value can be calculated.

[0061] The target absorption peak is the peak value of the absorption peak obtained by analyzing the electrical signal collected by the photodetector 300 after the laser is absorbed by the gas to be detected.

[0062] The baseline voltage value is the signal intensity when the laser is not absorbed by the gas to be detected.

[0063] Method ②: In some embodiments, the electrical signal is amplified by the electrical signal amplification component 600 and then analyzed. Figure 6As shown, first, the laser passes through the gas chamber 100 to be detected and is absorbed and attenuated by the gas to be detected, and then is transmitted out. The absorbed and attenuated laser is received by the photodetector 300; then, the photodetector 300 receives the absorbed and attenuated laser, and then the laser passes through the reference gas chamber 320, and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the laser detected by the detector body 310 into an electrical signal, thereby detecting the electrical signal of the gas to be detected through the detector body 310; then, the electrical signal amplification component 600 receives the electrical signal output by the detector body 310 and amplifies the electrical signal of the gas to be detected, and the amplified electrical signal is converted into a digital signal through the analog-to-digital converter 400, thereby obtaining the digital signal of the gas to be detected. Then, the target absorption peak and baseline voltage value of the gas to be detected are obtained by analyzing the digital signal of the gas to be detected. Finally, the ratio of the target absorption peak and the baseline voltage value and the gas concentration are nonlinearly functionally related (linearly related at low concentrations), and the gas concentration value can be calculated by obtaining the ratio of the target absorption peak and the baseline voltage value and substituting it into the corresponding functional relationship.

[0064] Method ③: In some embodiments, the electrical signal is amplified by the electrical signal amplification component 600 and filtered by the low-pass filter 700 before being analyzed. Figure 6 As shown, first, the laser passes through the gas chamber 100 to be tested and is absorbed and attenuated by the gas to be detected, and then passes out. The absorbed and attenuated laser is received by the photodetector 300; then, after the photodetector 300 receives the absorbed and attenuated laser, the laser passes through the reference gas chamber 320, and then passes through the detector body 310 to detect the laser, and the detector body 310 converts the optical signal of the laser detected by the detector body 310 into an electrical signal, thereby detecting the electrical signal of the gas to be detected through the detector body 310; then, the electrical signal amplifying component 600 receives the electrical signal output by the detector body 310 and amplifies the electrical signal of the gas to be detected, and the low-pass filter 700 can receive the electrical signal amplified by the electrical signal amplifying component 600 and filters the electrical signal amplified by the electrical signal amplifying component 600; finally, the filtered electrical signal is converted into a digital signal by the analog-to-digital converter 400. Next, the digital signal of the gas to be detected is used to analyze the target absorption peak and baseline voltage value of the gas to be detected. Finally, the ratio of the target absorption peak and the baseline voltage value is nonlinearly related to the gas concentration (linear relationship at low concentrations). By obtaining the ratio of the target absorption peak and the baseline voltage value and substituting it into the corresponding function relationship, the gas concentration value can be calculated.

[0065] A2. Based on the target absorption peak and the baseline voltage value, a preliminary detection concentration value of the gas chamber 100 to be tested is obtained.

[0066] Finally, by utilizing the characteristic that the ratio of the target absorption peak and the baseline voltage value is in a nonlinear functional relationship with the gas concentration, the gas concentration value is calculated as the preliminary detection concentration value of the gas chamber 100 to be tested by obtaining the ratio of the target absorption peak and the baseline voltage value and substituting it into the corresponding functional relationship.

[0067] A3. Compensating the preliminary detection concentration value based on the equivalent gas concentration value to obtain a compensated concentration value of the gas chamber 100 to be detected as the actual detection concentration value of the gas to be detected.

[0068] Specifically, the result obtained by subtracting the equivalent gas concentration value of the reference gas chamber 320 from the preliminary detection concentration value of the gas chamber 100 to be detected (i.e., the compensated concentration value of the gas chamber 100 to be detected) is used as the actual detection concentration value of the gas to be detected. In this way, by subtracting the equivalent gas concentration value of the reference gas chamber 320 from the preliminary detection concentration value of the gas chamber 100 to be detected, the preliminary detection concentration value of the gas chamber 100 to be detected can be compensated, so that when the concentration of the gas to be detected is low, the actual concentration value of the gas to be detected can still be detected, thereby reducing the gas concentration detection lower limit of the laser gas detection device and improving the performance of the laser gas detection device.

[0069] In some embodiments, steps A1 to A3 are implemented based on the digital processing module 500; in some embodiments, the digital signal of the gas to be detected converted by the analog-to-digital converter 400 can also be sent to other processors, and the other processors will perform the concentration detection process of steps A1 to A3 based on the digital signal of the gas to be detected.

[0070] For further information, please refer to Figure 8 , Figure 8 This is a flow chart of the reference gas chamber 320 leakage detection and equivalent gas concentration value calibration provided in the embodiment of the present application. The gas concentration detection method may further include the following steps B1 to B3:

[0071] B1. When the gas chamber 100 to be tested is not loaded with the gas to be tested, the current gas concentration value of the gas chamber 100 to be tested is obtained.

[0072] The current gas concentration value of the gas chamber 100 to be tested is equal to the difference between the current preliminary detection concentration value of the gas chamber 100 to be tested and the equivalent gas concentration value. The determination method of the current preliminary detection concentration value of the gas chamber 100 to be tested can refer to the relevant description of step A2, which will not be repeated here.

[0073] For example, Figure 6As shown, when the gas chamber to be tested is not loaded with the gas to be tested, first, the digital processing module 500 generates a digital signal through the signal generator; then, the digital-to-analog converter 800 converts the digital signal generated by the signal generator of the digital processing module 500 into an analog signal; then, the laser driver 900 receives the analog signal of the digital-to-analog converter 800 and generates a low-frequency periodic tuning current under the action of the analog signal; then, the laser 200 emits a laser under the action of the low-frequency periodic tuning current and injects the laser into the gas chamber to be tested 100; then, the laser passes through the gas chamber to be tested 100 and is received by the photodetector 300, and the photodetector 300 receives the laser. After receiving the laser, the laser passes through the reference gas chamber 320 and then passes through the detector body 310 to detect the laser. The detector body 310 converts the optical signal of the detected laser into an electrical signal, thereby detecting the electrical signal of the gas to be detected through the detector body 310; then, the electrical signal amplifying component 600 receives the electrical signal output by the detector body 310 and amplifies the electrical signal of the gas to be detected, and the low-pass filter 700 can receive the electrical signal amplified by the electrical signal amplifying component 600 and filter the electrical signal amplified by the electrical signal amplifying component 600; finally, the filtered electrical signal is converted into a digital signal by the analog-to-digital converter 400. Next, the digital signal converted by the analog-to-digital converter 400 is analyzed to obtain the target absorption peak and the baseline voltage value. Finally, the characteristic that the ratio of the target absorption peak and the baseline voltage value has a nonlinear functional relationship with the gas concentration (a linear relationship at low concentrations) is utilized. By obtaining the ratio of the target absorption peak and the baseline voltage value and substituting it into the corresponding functional relationship, the gas concentration value is calculated as a preliminary detection concentration value; the preliminary detection concentration value is subtracted from the equivalent gas concentration value of the reference gas chamber 320, and the result obtained is used as the current gas concentration value of the gas chamber 100 to be tested.

[0074] B2. If it is detected that the current gas concentration value of the gas chamber 100 to be tested is a negative value, then the duration of the current gas concentration value of the gas chamber 100 to be tested being a negative value is detected.

[0075] B3. If the duration of the negative value of the current gas concentration value of the gas chamber to be tested 100 is greater than the preset duration, and the current gas concentration value within the preset duration is less than the preset concentration value, a gas leakage alarm is issued for the reference gas chamber.

[0076] B4. If the duration of the negative value of the current gas concentration value of the gas chamber 100 to be tested is greater than the preset duration, and the current gas concentration value is less than the preset concentration value within the preset duration, the equivalent gas concentration value is updated until the current gas concentration value obtained according to the updated equivalent gas concentration value is equal to zero.

[0077] In this way, by adding real-time judgment on whether the current gas concentration value is a negative value, after the negative value is detected and stabilized for a period of time, and then by setting the relevant parameter thresholds, the slow leakage of the reference gas chamber 320 can be accurately screened out and real-time zero calibration can be performed, thereby eliminating the influence of the slow leakage of the reference gas chamber 320 and ensuring the gas concentration detection accuracy of the laser gas detection device.

[0078] For example, Figure 8 As shown, considering that slow leakage may occur during the long-term detection of the reference gas chamber 320, a real-time zeroing calibration processing method is proposed through steps B1 to B4. Assuming that the equivalent gas concentration value of the reference gas chamber 320 is 6%LEL, first, it is determined in real time whether the current gas concentration value of the gas chamber 100 to be tested is a negative value. If a negative value is detected, it is determined whether the negative value lasts for 300s, otherwise the current gas concentration value is output; if the negative value lasts for 300s, it is determined whether the negative values ​​within 300s are all less than -6%LEL, otherwise Then the current concentration value is output; if the negative values ​​within 300s are all less than -6%LEL, a sensor fault is reported; otherwise, it is judged whether the difference between the average of the first 100s and the average of the last 100s within 300s is less than 1%LEL; if the difference between the average of the first 100s and the average of the last 100s is less than 1%LEL, the current gas concentration value is cleared and calibrated (i.e., the equivalent gas concentration value is updated so that the current gas concentration value obtained according to the updated equivalent gas concentration value is equal to zero), otherwise, it is reported that the reference gas chamber 320 is damaged. In this way, through this real-time clearing and calibration processing method, the slow leakage of the reference gas chamber 320 can be detected in real time and the influence of the slow leakage of the reference gas chamber 320 can be eliminated, thereby ensuring the gas concentration detection accuracy of the laser gas detection device.

[0079] Exemplarily, the specific operation of performing zero calibration of the current gas concentration value (i.e., updating the equivalent gas concentration value so that the current gas concentration value obtained according to the updated equivalent gas concentration value is equal to zero) can be as follows: If the current gas concentration value is a negative value, the equivalent gas concentration value (e.g., 5%) of the reference gas chamber 320 after the leakage can be inferred based on the current gas concentration value, wherein the equivalent gas concentration value (e.g., 5%) of the reference gas chamber 320 after the leakage = the preliminary detection concentration value detected after the leakage (e.g., 5%) - the current actual gas concentration value of the gas chamber 100 to be tested (i.e., 0%, the gas chamber 100 to be tested is not currently loaded with gas).

[0080] From the above content, it can be seen that the laser 200 of the laser gas detection device emits a laser and injects the laser into the gas chamber to be detected 100 loaded with the gas to be detected, and the detector body 310 detects the laser passing through the gas chamber to be detected 100 and the reference gas chamber 320 to obtain the electrical signal of the gas to be detected; the equivalent gas concentration value of the reference gas chamber 320 is obtained; based on the equivalent gas concentration value and the electrical signal of the gas to be detected, the actual detection concentration value of the gas to be detected is obtained by analysis; because the equivalent gas concentration value of the reference gas chamber 320 can be used for compensation, the absorption peak can still be detected when the concentration of the gas to be detected is low, which solves the problem that the absorption peak cannot be detected at low concentrations and the gas concentration value cannot be calculated, so that when the concentration of the gas to be detected is low, the actual concentration value of the gas to be detected can still be detected, thereby reducing the gas concentration detection lower limit of the laser gas detection device and improving the performance of the laser gas detection device.

[0081] The above is a detailed introduction to a laser gas detection device and a gas concentration detection method provided in the embodiments of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method and its core idea of ​​the present application. At the same time, for technicians in this field, according to the idea of ​​the present application, there will be changes in the specific implementation methods and application scopes. For example, the various technical features in the above embodiments can be arbitrarily combined, as long as there is no conflict or contradiction between the combinations of features. Therefore, the arbitrary combination of various technical features in the above embodiments also belongs to the scope disclosed in this specification. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A laser gas detection device, characterized in that: The laser gas detection device comprises a laser, a gas chamber to be detected and a photoelectric detector, wherein the gas chamber to be detected is the internal optical-mechanical structure space of the laser gas detection device, and the photoelectric detector comprises a detector body and a reference gas chamber; The gas chamber to be tested is used to load the gas to be tested; A laser, used for emitting laser light and injecting the laser light into the gas chamber to be tested; A reference gas chamber, used to transmit the laser emitted from the gas chamber to be tested; The detector body is used to detect the laser light passing through the gas chamber to be detected and the reference gas chamber to obtain the electrical signal of the gas to be detected.

2. The laser gas detection device according to claim 1, characterized in that: The laser gas detection device also includes an analog-to-digital converter and a digital processing module, and the analog-to-digital converter and the digital processing module are connected; The analog-to-digital converter is used to convert the electrical signal of the gas to be detected into a digital signal; The digital signal is transmitted to the digital processing module, and the digital processing module analyzes the digital signal to obtain the actual detection concentration value of the gas to be detected.

3. The laser gas detection device according to claim 2, characterized in that: The laser gas detection device further comprises an electrical signal amplifying component, and the electrical signal amplifying component is connected to the photoelectric detector; The electrical signal amplifying component is used to receive the electrical signal output by the photoelectric detector and amplify the electrical signal of the gas to be detected; The analog-to-digital converter converts the amplified electrical signal of the gas to be detected into a digital signal.

4. The laser gas detection device according to claim 1, characterized in that: The laser gas detection device further comprises a low-pass filter, and the low-pass filter is used to filter the electrical signal of the gas to be detected.

5. The laser gas detection device according to claim 1, characterized in that: The laser gas detection device further comprises a laser driver, which is used to generate a low-frequency periodic tuning current; the laser emits laser light under the action of the current and injects the laser light into the gas chamber to be detected.

6. A gas concentration detection method, characterized in that: The method comprises: The laser of the laser gas detection device is used to emit laser light and the laser light is injected into a gas chamber to be detected which is loaded with the gas to be detected, wherein the laser gas detection device comprises a laser, a gas chamber to be detected and a photoelectric detector, the gas chamber to be detected is the internal optical-mechanical structure space of the laser gas detection device, and the photoelectric detector comprises a detector body and a reference gas chamber; The detector body detects the laser light passing through the gas chamber to be detected and the reference gas chamber to obtain an electrical signal of the gas to be detected; Obtaining an equivalent gas concentration value of the reference gas chamber; An analysis is performed based on the equivalent gas concentration value and the electrical signal of the gas to be detected to obtain the actual detection concentration value of the gas to be detected.

7. The gas concentration detection method according to claim 6, characterized in that: The step of analyzing the equivalent gas concentration value and the electrical signal of the gas to be detected to obtain the actual detection concentration value of the gas to be detected includes: Analyzing and processing the electrical signal of the gas to be detected to obtain a target absorption peak and a baseline voltage value of the gas to be detected; Based on the target absorption peak and the baseline voltage value, obtaining a preliminary detection concentration value of the gas chamber to be tested; The preliminary detection concentration value is compensated based on the equivalent gas concentration value to obtain a compensated concentration value of the gas chamber to be detected as the actual detection concentration value of the gas to be detected.

8. The gas concentration detection method according to claim 6, characterized in that: The obtaining of the equivalent gas concentration value of the reference gas chamber comprises: According to the gas chamber length L1 of the reference gas chamber, the optical path length L2 of the laser gas detection device, the gas concentration value C1 in the reference gas chamber and a preset equivalent concentration calculation formula, the equivalent gas concentration value C of the reference gas chamber is calculated, and the preset equivalent concentration calculation formula is:

9. The gas concentration detection method according to claim 6, characterized in that: The method further comprises: When the gas chamber to be tested is not loaded with the gas to be tested, obtaining a current gas concentration value of the gas chamber to be tested, wherein the current gas concentration value is equal to a difference between a current preliminary detection concentration value of the gas chamber to be tested and the equivalent gas concentration value; If it is detected that the current gas concentration value of the gas chamber to be tested is a negative value, detecting the duration of the current gas concentration value of the gas chamber to be tested being a negative value; If the duration of the negative value of the current gas concentration value of the gas chamber to be tested is greater than the preset duration, and the current gas concentration value within the preset duration is less than the preset concentration value, a gas leakage alarm is issued for the reference gas chamber.

10. The gas concentration detection method according to claim 9, characterized in that: The method further comprises: If the duration of the negative value of the current gas concentration value of the gas chamber to be tested is greater than the preset duration, and the current gas concentration value is less than the preset concentration value within the preset duration, the equivalent gas concentration value is updated until the current gas concentration value obtained according to the updated equivalent gas concentration value is equal to zero.

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