Industrial gas concentration detection system

Abstract

The invention relates to the technical field of gas detection, and particularly discloses an industrial gas concentration detection system, which is used for solving the problems of signal attenuation, low detection precision, high cost and poor stability caused by environmental interference and multi-laser beam combination since a correlation type optical machine adopts a single-path and fixed compensation method and cannot measure multi-component gas at the same time. Comprising a transmitting end and a receiving end, a laser is arranged in the transmitting end, a red light generator is arranged in the transmitting end, an off-axis parabolic mirror is arranged on one side of the transmitting end, an optical filter is arranged above the off-axis parabolic mirror, a photoelectric detector is arranged above the optical filter, a first window is arranged on one side of the off-axis parabolic mirror, a second window is packaged in the receiving end, and a full-angle reflector is arranged on one side of the second window. The photoelectric detector is sequentially connected with a data inversion analysis module, a dynamic environment compensation module and an environment sensing module; by optimizing optical design and dynamic environment compensation, multi-gas concentration detection is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and more specifically, to an industrial gas concentration detection system. Background Art

[0002] In the petrochemical, metallurgical and environmental industries, the heating furnace is a key production equipment. There are usually multiple gas components coexisting in the furnace, among which CO, N2O and H2O are the most common gas components. The detection of the concentration of these three gases plays an important role in production. The through-beam optical machine is a conventional detection equipment for detecting the concentration of gas components in the heating furnace. The traditional through-beam optical machine structure uses a near-infrared laser as the transmitting end. After the emitted laser is absorbed by the gas to be tested, a photodetector is placed as the receiving end to receive the optical signal. This method can only obtain a straight line path from the transmitting end to the receiving end, and can only detect one gas. The transmitting end and the receiving end are All of these methods require the laying of electrical wires, which makes the signal susceptible to interference. In addition, the light emitted by two or more lasers is combined. After the combined laser is absorbed by the gas to be measured, a reflector is placed to reflect the laser back to the transmitting end, and then the laser is separated by wavelength using spectrometers of different wavelengths. Then, the corresponding photodetectors are placed in sequence to detect the optical signal. Although this method obtains a double straight line path from the transmitting end to the receiving end, the use of multiple lasers and photodetectors will increase the cost of use and bring trouble to the mechanical structure layout of the transmitting and receiving ends. The use of multiple spectrometers will also weaken the optical signal, affecting the detection of optical signals. The internal ambient temperature and pressure of the heating furnace change dramatically and are highly time-varying. The traditional temperature and pressure fixed compensation method uses the ideal gas state equation to calculate a correction factor based on the standard data at the temperature and pressure pre-measured in the laboratory, and then makes a very simple linear compensation based on the current temperature and pressure during measurement. However, fixed coefficients are usually used, which is difficult to adapt to the needs of nonlinear changes in dynamic environments. Summary of the invention

[0003] In order to overcome the above-mentioned defects of the prior art, the present invention provides an industrial gas concentration detection system, which realizes high-precision and stable multi-gas concentration detection by optimizing optical design and dynamic environmental compensation.

[0004] In industrial heating furnaces, the sensitivity of the absorption characteristics of different gases to environmental changes varies significantly. The absorption line of CO is wider than that of N2O and H2O, and its response to environmental fluctuations is relatively stable. The use of linear function compensation can smoothly adjust the dynamic compensation effect of the environment; N2O is very sensitive to temperature and pressure changes, and its absorption spectrum is narrow. It is necessary to use a nonlinear function with a faster response so that the compensation weight can be quickly adjusted when the environment changes suddenly; the absorption characteristics of H2O are extremely dependent on humidity changes, and its response is obviously nonlinear. It is necessary to make the error caused by humidity changes significantly amplified during feedback so as to effectively compensate. The setting of different gating functions can effectively reduce the measurement error caused by environmental changes, reduce the dependence of the overall industrial gas detection on the performance of the environmental sensor module, reduce the cost of use, and reduce the cross-interference of each gas in multi-component gas detection, thereby improving the accuracy of gas concentration inversion.

[0005] To achieve the above object, the present invention provides the following technical solutions: An industrial gas concentration detection system includes a transceiver and a reflector, wherein a gas to be detected is arranged between the transceiver and the reflector, and a laser is arranged in the transceiver. The wavelength range of the laser beam emitted after temperature and current modulation is 2202.8-2205.6cm -1 (4533.91~4539.67nm), a red light generator is packaged inside, an off-axis parabolic mirror with a hole in the middle is arranged on one side of the laser, a filter is arranged above the off-axis parabolic mirror with a hole in the middle, a photodetector is arranged above the filter, which is responsible for converting the processed optical signal into an electrical signal, a window piece 1 is arranged on the side of the off-axis parabolic mirror away from the laser, a window piece 2 is packaged in the reflecting end, a full-angle reflector is arranged on one side of the window piece 2, the photodetector is connected to a data inversion analysis module, the data inversion analysis module is connected to a dynamic environment compensation module, the dynamic environment compensation module is connected to an environmental The environmental sensing module collects the temperature, humidity and pressure in the heating furnace in real time and transmits them to the dynamic environmental compensation module. The dynamic environmental compensation module uses the acquired data to construct a normalized vector of environmental variables, uses the preset coupling analysis formula to nonlinearly map the normalized deviation of environmental parameters, obtains environmental parameter mapping items, weightedly accumulates the historical gas concentration inversion error within the set time window, obtains environmental parameter time integral items, and uses the preset dynamic environmental compensation formula to obtain the dynamic environmental compensation value based on the environmental parameter mapping items and the environmental parameter time integral items. The preset dynamic environmental compensation formula is: ; Where: is the time variable, is the dynamic environment compensation factor, is the environment parameter mapping item, is the time integral term of the environmental parameter, It is a gating function. For CO, N2O, and H2O gas concentration detection, use the corresponding gating function. is the overall scaling factor, obtained by offline calibration.

[0006] As a further solution of the present invention, the optical path between the transceiver end and the reflector end includes: The red indicator light emitted by the red light generator is combined with the infrared light emitted by the laser as the output light beam, which first passes through the middle opening of the off-axis parabolic mirror and window one, enters the gas area to be measured, and completes the first absorption; then the laser beam passes through window two and shoots to the full-angle reflector, and after reflection along the original path, it passes through window two again and enters the gas area to be measured for the second absorption (to effectively extend the optical path and enhance the absorption signal), and the reflected light beam passes through window one and is repeatedly incident on the parabola of the off-axis parabolic mirror, and its reflected light is focused on the light sensitive surface of the photodetector after passing through the filter, and the light signal collected by the photodetector is converted into an electrical signal through photoelectric conversion, and then the data inversion analysis module performs detection electrical signal processing and gas concentration inversion calculation, and performs dynamic environment correction based on the dynamic environment compensation algorithm, and feedback controls the laser.

[0007] As a further solution of the present invention, in the dynamic environment compensation module, the gating function used for CO gas concentration detection in the dynamic environment compensation formula uses a linear combination of environmental parameter mapping items and environmental parameter time integral items and limits its output range to [0,1], so as to smoothly adjust the CO gas concentration detection. The gating function formula used by the dynamic environment compensation formula for CO gas concentration detection is: ; Where: is the gating function value used for CO gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection. The environmental parameters involve temperature, humidity, and pressure. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection.

[0008] As a further solution of the present invention, in the dynamic environment compensation module, the gating function used for N2O gas concentration detection in the dynamic environment compensation formula enables the N2O photoelectric signal to adjust the dynamic environment compensation weight at a set speed when reaching a set critical point, thereby improving the feedback sensitivity when the environment suddenly changes. The gating function formula used for N2O gas concentration detection in the dynamic environment compensation formula is: ; Where: is the gating function value for N2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection. The environmental parameters involve temperature and pressure. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection.

[0009] As a further solution of the present invention, in the dynamic environment compensation module, the gating function used for H2O gas concentration detection in the dynamic environment compensation formula adopts an exponential function to compensate for the error of water vapor concentration caused by humidity change. The gating function formula used for H2O gas concentration detection in the dynamic environment compensation formula is: ; Where: is the gating function value for H2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing H2O gas concentration detection. The environmental parameters involve humidity. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when detecting the H2O gas concentration.

[0010] As a further solution of the present invention, in the data inversion analysis module, the detection electrical signal processing, gas concentration inversion calculation, dynamic environment correction based on the dynamic environment compensation algorithm, and feedback control of the laser process include: Step 1, signal acquisition and preprocessing: the photodetector converts the light signal after two absorptions into an electrical signal, filters the electrical signal, removes background noise and baseline drift; Step 2, calculation of dynamic environmental compensation factor: the environmental sensing module collects the temperature, humidity and pressure in the heating furnace in real time, constructs a normalized environmental state vector, uses a preset coupling analysis formula to perform nonlinear mapping on the environmental parameters, obtains environmental parameter mapping items, and at the same time, performs exponential weighted integration on the historical gas concentration inversion error within the set time window to obtain the environmental parameter time integral item. According to the different gases being measured, the dynamic environmental compensation module uses the corresponding gating function to determine the relative weights between the environmental parameter mapping items and the environmental parameter time integral items, and calculates the current dynamic environmental compensation factor according to the dynamic environmental compensation formula; Step 3, signal correction and concentration inversion: The electrical signal obtained in step 1 is corrected using the dynamic environment compensation factor obtained in step 2. The corrected electrical signal is integrated to extract the integral area of ​​the target gas absorption peak. The current gas concentration is calculated by combining the Beer-Lambert law and the preset inversion formula. Step 4, closed-loop feedback control: compare the current gas concentration obtained in step 3 with the standard gas concentration, calculate the concentration error, feed this concentration error back to the dynamic environment compensation factor through the environmental parameter time integral term, and transmit it to the laser as a feedback signal. The laser uses this error to adjust the modulation parameters of temperature and current to ensure that the output wavelength is maintained within the preset range, optimize the absorption signal and minimize the data inversion error; Step 5, continuous online adaptive update: The environmental sensing module continuously collects data, and the dynamic environmental compensation module uses the latest environmental parameter mapping item and the environmental parameter time integral item feedback to calculate the latest dynamic environmental compensation factor. The corrected electrical signal is inverted to obtain the gas concentration, and the gas concentration error is fed back to the dynamic environmental compensation and laser control. The weight parameters in each gas gating parameter are continuously optimized through the adaptive update algorithm of online learning and gradient descent.

[0011] As a further solution of the present invention, in the dynamic environment compensation module, the preset coupling analysis formula takes into account the nonlinear coupling effect between the temperature, pressure and humidity in the heating furnace, and the coupling analysis formula based on the radial basis function network maps the normalized environmental parameters to the environmental parameter mapping items. The preset coupling analysis formula is: ; Where: is the index of the preset basis function, is the number of preset basis functions, For the The weights of each basis function are calibrated offline. For the The central vector of the basis function is derived from the cluster analysis of historical environmental data. is the normalized environmental parameter vector, , , , At the time The temperature, pressure and humidity data collected in real time by the environmental sensor module, , , They are the temperature reference value, pressure reference value, and humidity reference value of the calibration standard conditions. , , They are the standard deviations of temperature, humidity, and pressure based on historical data statistics. For the The inverse matrix of the covariance matrix of the basis functions is used to quantify the impact of the actual deviation on the mapped value.

[0012] As a further solution of the present invention, in the data inversion analysis module, step 4 closed-loop feedback adjustment of the temperature and current modulation parameters of the laser includes temperature modulation feedback, current modulation feedback and joint control, wherein the temperature modulation feedback uses a PID algorithm to obtain a temperature adjustment amount according to the detected gas concentration error, and transmits the temperature adjustment amount to the laser to adjust the operating temperature of the laser chip so that the output laser wavelength shifts toward the target absorption peak. The current modulation feedback uses a PID control algorithm to obtain a current adjustment amount, and transmits the current adjustment amount to the laser to adjust the baseline current and modulation amplitude of the drive circuit, and adjust the output power and wavelength accordingly. The joint control is based on a decoupling algorithm and an online self-learning strategy to simultaneously adjust the operating temperature of the laser chip and the output power and wavelength of the drive circuit to keep the output stable within a set threshold.

[0013] As a further solution of the present invention, the diameter of the central opening of the off-axis parabolic mirror is set to between 3 and 5 mm, and the appropriate focal length and curvature are selected according to the optical path length and the expected spot size. The installation angle accuracy is controlled within ±0.1°. Window one and window two are both high-temperature resistant windows made of sapphire with a thickness of between 1 and 3 mm. The surface is provided with anti-reflection and heat-resistant coatings. The filter is a mid-infrared filter with a central wavelength of 4.535 μm and a bandwidth of 10 nm. The projection rate in the target band is greater than or equal to 90%, and the optical density in the 2.2-2.4 μm out-of-band area and related interference bands is greater than or equal to 4.

[0014] As a further solution of the present invention, the laser is a mid-infrared quantum cascade laser, and the output power of the red indicator light accounts for 0.5% to 2% of the infrared light output power.

[0015] Technical effects of the industrial gas concentration detection system of the present invention: The system proposed by the present invention is simple, and the operation is simple when the optical path is collimated and aligned. The CO absorption line within the set threshold range of 2.3μm and the interference of N2O and H2O absorption lines at other positions can be filtered out by using a filter, so as to improve the signal-to-noise ratio. The concentrations of three molecules of CO, N2O and H2O can be simultaneously detected by using a single optical path, a single laser and a single photodetector. The reflection function of the passive end full-angle reflector is used to make the laser detection optical path length twice that of an ordinary opposed optical path, so as to improve the detection accuracy of the gas concentration by increasing the absorption optical path. The dynamic environment compensation algorithm and the closed-loop feedback control technology are used to realize the real-time adaptive correction of the laser output error caused by environmental fluctuations such as temperature, pressure and humidity in the heating furnace, so as to improve the response speed and anti-interference performance under complex working conditions in the heating furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A system block diagram of the system proposed by the present invention; Figure 2 A schematic diagram of the optical path of the system proposed by the present invention; Figure 3 The direct absorption spectra of CO, N2O and H2O simulated by the present invention; Figure 4 This is a second harmonic absorption signal diagram of the present invention for simultaneously measuring CO, N2O, and H2O; Figure 5 The following is a workflow diagram of the data inversion analysis module of the present invention; In the figure: 01-laser, 02-off-axis parabolic mirror, 03-window one, 04-filter, 05-photodetector, 06-window two, 07-full-angle reflector, 101-transmitter and receiver, 102-reflector. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1

[0019] like Figure 1 As shown, an industrial gas concentration detection system proposed by the present invention includes a transceiver end 101 and a reflector end 102, a gas to be detected is arranged between the transceiver end 101 and the reflector end 102, a laser 01 is arranged in the transceiver end 101, and the wavelength range of the laser beam emitted by the laser 01 after temperature and current modulation is 2202.8~2205.6cm -1(4533.91~4539.67nm), a red light generator is packaged inside, an off-axis parabolic mirror 02 with a hole in the middle is provided on one side of the laser 01, a filter 04 is provided above the off-axis parabolic mirror 02 with a hole in the middle, a photodetector 05 is provided above the filter 04, which is responsible for converting the processed optical signal into an electrical signal, a window 1 03 is provided on the side of the off-axis parabolic mirror 02 away from the laser 01, a window 2 06 is packaged in the reflecting end 102, a full-angle reflector 07 is provided on one side of the window 2 06, the photodetector 05 is connected to a data inversion analysis module, and the data inversion analysis module is connected to a dynamic environment compensation The dynamic environment compensation module is connected to the environment sensor module. The environment sensor module collects the temperature, humidity and pressure in the heating furnace in real time and transmits them to the dynamic environment compensation module. The dynamic environment compensation module uses the acquired data to construct a normalized vector of environmental variables, uses a preset coupling analysis formula to nonlinearly map the normalized deviation of environmental parameters, obtains environmental parameter mapping items, weightedly accumulates the historical gas concentration inversion error within the set time window, obtains the environmental parameter time integral item, and obtains the dynamic environment compensation value based on the environmental parameter mapping item and the environmental parameter time integral item using the preset dynamic environment compensation formula. The preset dynamic environment compensation formula is: ; Where: is the time variable, is the dynamic environment compensation factor, is the environment parameter mapping item, is the time integral term of the environmental parameter, The gating function is used for CO, N2O, and H2O gas concentration detection. The corresponding gating functions are used for CO, N2O, and H2O gas concentration detection. In industrial heating furnaces, the absorption characteristics of different gases have significant differences in sensitivity to environmental changes. By setting different gating functions for CO, N2O, and H2O, the measurement error caused by environmental changes can be effectively reduced, and the system's dependence on the performance of the environmental sensor module can be reduced, thereby reducing the cost of use and reducing the cross-interference between gases in multi-component gas detection, ultimately achieving a significant improvement in the accuracy of gas concentration inversion. is the overall scaling factor, obtained by offline calibration.

[0020] It should be noted that the diameter of the central opening of the off-axis parabolic mirror 02 is set between 3 and 5 mm, and the appropriate focal length and curvature are selected according to the optical path length and the expected spot size. The installation angle accuracy is controlled within ±0.1°. The window 1 03 and the window 2 06 are both high-temperature resistant windows made of sapphire with a thickness of 1 to 3 mm. The surface is provided with anti-reflection and heat-resistant coatings. The central wavelength of the filter 04 is 4.535 μm, the bandwidth is 10 nm, the projection rate in the target band is greater than or equal to 90%, and the optical density in the 2.2 to 2.4 μm out-band area and related interference bands is greater than or equal to 4. In the laser 01, the output power of the red indicator light accounts for 0.5% to 2% of the infrared light output power.

[0021] By strictly limiting the center opening diameter of the off-axis parabolic mirror 02 to between 3 and 5 mm, accurately selecting the appropriate focal length and curvature according to the optical path length and the expected spot size, and controlling the installation angle within ±0.1°, it is ensured that the laser beam maintains high collimation and low wavefront error after reflection, and achieves stable focusing and efficient light transmission; at the same time, the window piece 1 03 and the window piece 2 06 made of sapphire are controlled at a thickness of between 1 and 3 mm, and anti-reflection and anti-heat coatings are applied on the surface to ensure that it has high transmittance and excellent thermal stability in a high temperature environment, avoiding thermal expansion or thermal interference. The optical performance is degraded; in addition, the filter 04 is designed with a central wavelength of 4.535μm and a bandwidth of 10nm. The transmittance in the target band is not less than 90%, and the optical density in the interference bands such as 2.2-2.4μm reaches or exceeds 4, thereby effectively filtering out stray light and interference signals other than the absorption lines of CO, N2O, and H2O, ensuring the purity and high signal-to-noise ratio of the detection spectrum; furthermore, the red light generator encapsulated in the laser 01, the output red light indicator light power of which only accounts for 0.5% to 2% of the infrared light output power, can provide sufficient visual alignment assistance without interfering with the infrared signal.

[0022] It should be noted that if Figure 2 As shown, the optical path between the transceiver end 101 and the reflector end 102 includes: The red indicator light emitted by the red light generator is combined with the infrared light emitted by the laser 01 as the output light beam, which first passes through the middle opening of the off-axis parabolic mirror 02 and the window one 03, enters the gas area to be measured, and completes the first absorption; then the laser beam passes through the window two 06 and shoots to the full-angle reflector 07, and after reflection along the original path, it passes through the window two 06 again to enter the gas area to be measured, and is absorbed for the second time (to effectively extend the optical path and enhance the absorption signal), and the reflected light beam passes through the window one 03 and is incident on the parabola of the off-axis parabolic mirror 02 again, and its reflected light passes through the filter 04 and is focused onto the light sensitive surface of the photodetector 05, and the light signal collected by the photodetector 05 is converted into an electrical signal through photoelectric conversion, and then the data inversion analysis module performs detection electrical signal processing and gas concentration inversion calculation, and performs dynamic environment correction based on the dynamic environment compensation algorithm, and feedback controls the laser 01.

[0023] The system proposed by the present invention is simple, and the operation is simple when the optical path is aligned and aligned. The use of the filter 04 can filter out the CO absorption line within the set threshold range of 2.3μm and the interference of the N2O and H2O absorption lines at other positions, thereby improving the signal-to-noise ratio. The use of a single optical path, a single laser 01, and a single photodetector 05 can simultaneously detect the concentrations of three molecules of CO, N2O, and H2O. By utilizing the reflection function of the passive end full-angle reflector 07, the laser detection optical path length is twice that of the ordinary reflected optical path, thereby improving the absorption optical path and thus improving the detection accuracy of the gas concentration.

[0024] It should be noted that in the dynamic environment compensation module, the gating function used for CO gas concentration detection in the dynamic environment compensation formula uses a linear combination of environmental parameter mapping items and environmental parameter time integral items and limits its output range to [0,1] to smoothly adjust the CO gas concentration detection. The gating function formula used by the dynamic environment compensation formula for CO gas concentration detection is: ; Where: is the gating function value used for CO gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection. The environmental parameters involve temperature, humidity, and pressure. , They are the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection, which are determined based on offline calibration and historical data statistics.

[0025] CO has a wide absorption line and responds relatively smoothly to temperature, pressure and humidity fluctuations. Therefore, linear function compensation is used to achieve smooth regulation. and the time integral of the environmental parameters The weight factors and Perform linear combination and use min-max function to limit the output to the range of [0,1] to form a gating function This technical solution enables smooth adjustment of CO gas concentration detection in the heating furnace, reduces errors caused by temperature, humidity and pressure fluctuations, thereby reducing dependence on environmental sensor performance, improving the accuracy of data inversion and the overall stability of the system, and reducing cross-interference in multi-component gas detection, ensuring reliable detection results.

[0026] It should be noted that in the dynamic environment compensation module, the gating function used for N2O gas concentration detection in the dynamic environment compensation formula enables the N2O photoelectric signal to adjust the dynamic environment compensation weight at a set speed when reaching the set critical point, thereby improving the feedback sensitivity when the environment changes suddenly. The gating function formula used for N2O gas concentration detection in the dynamic environment compensation formula is: ; Where: is the gating function value for N2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection. The environmental parameters involve temperature and pressure. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection.

[0027] The absorption spectrum of N2O is narrow and extremely sensitive to temperature and pressure changes. It is necessary to use a nonlinear function with rapid response so that the compensation weight can be adjusted quickly when the environment suddenly changes. Function builds a gating function for N2O gas concentration detection , and introduce the environment parameter mapping item and the time integral of the environmental parameters A linear combination of and The weight factor is used so that when the environment changes suddenly, the dynamic environmental compensation of N2O concentration can quickly adjust the compensation weight according to the change of the input signal in a short time, especially when dealing with environmental fluctuations such as temperature and pressure changes. It enhances the sensitivity of feedback, improves the response speed and accuracy of the detection system under rapid environmental changes, avoids the feedback delay caused by over-compensation, makes the real-time measurement of N2O gas concentration more stable and accurate, and effectively improves the adaptability to environmental changes in high temperature or severe working conditions, thereby improving the anti-interference performance of the entire system and the detection accuracy of multi-component gases.

[0028] It should be noted that in the dynamic environment compensation module, the gating function used for H2O gas concentration detection in the dynamic environment compensation formula adopts an exponential function to compensate for the error of water vapor concentration caused by humidity changes. The gating function formula used for H2O gas concentration detection in the dynamic environment compensation formula is: ; Where: is the gating function value for H2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing H2O gas concentration detection. The environmental parameters involve humidity. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when detecting the H2O gas concentration.

[0029] The absorption characteristics of H2O are extremely dependent on humidity changes, and its response is obviously nonlinear. It is necessary to design a function that can significantly amplify the error caused by humidity changes during feedback. This technical solution realizes accurate compensation for the nonlinear error caused by humidity changes for H2O gas concentration detection. The principle is to first use the environmental sensor module to collect the humidity data in the heating furnace in real time, and then construct the environmental parameter mapping item after normalization. (Reflects the deviation of humidity from the reference value and standard deviation), and at the same time, the exponentially weighted integration of the historical concentration inversion error within the set time window is performed to obtain the environmental parameter time integral term ; Then through the preset weight factor and right , A nonlinear weighted combination is performed, and the rapid decay characteristics of the exponential function are used to significantly amplify the impact of humidity fluctuations on the water vapor absorption signal. This enables the system to quickly adjust the dynamic environmental compensation weight when encountering a sharp change in humidity, and to correct the measurement deviation caused by humidity fluctuations in real time, which significantly improves the accuracy of water vapor concentration inversion and the overall stability of the system, reduces the dependence on the high-precision performance of environmental sensors and the risk of cross-interference between multi-component gases, thereby providing a strong technical guarantee for the real-time, accurate and stable online detection of H2O gas concentration in industrial heating furnaces, and further enhances the response speed and anti-interference ability of the system in complex high-temperature dynamic environments.

[0030] It should be noted that if Figure 5 As shown, in the data inversion analysis module, the process of performing detection electrical signal processing, gas concentration inversion calculation, dynamic environment correction based on the dynamic environment compensation algorithm, and feedback control of the laser 01 includes: Step 1, signal acquisition and preprocessing: the photodetector 05 converts the light signal after two absorptions into an electrical signal, filters the electrical signal, removes background noise and baseline drift; Step 2, calculation of dynamic environmental compensation factor: the environmental sensing module collects the temperature, humidity and pressure in the heating furnace in real time, constructs a normalized environmental state vector, uses a preset coupling analysis formula to perform nonlinear mapping on the environmental parameters, obtains environmental parameter mapping items, and at the same time, performs exponential weighted integration on the historical gas concentration inversion error within the set time window to obtain the environmental parameter time integral item. According to the different gases being measured, the dynamic environmental compensation module uses the corresponding gating function to determine the relative weights between the environmental parameter mapping items and the environmental parameter time integral items, and calculates the current dynamic environmental compensation factor according to the dynamic environmental compensation formula; Step 3, signal correction and concentration inversion: The electrical signal obtained in step 1 is corrected using the dynamic environment compensation factor obtained in step 2. The corrected electrical signal is integrated to extract the integral area of ​​the target gas absorption peak. The current gas concentration is calculated by combining the Beer-Lambert law and the preset inversion formula. Step 4, closed-loop feedback control: compare the current gas concentration obtained in step 3 with the standard gas concentration, calculate the concentration error, feed this concentration error back to the dynamic environment compensation factor through the environmental parameter time integral term, and transmit it to the laser 01 as a feedback signal. The laser 01 uses this error to adjust the modulation parameters of temperature and current to ensure that the output wavelength is maintained within the preset range, optimize the absorption signal and minimize the data inversion error; Step 5, continuous online adaptive update: The environmental sensing module continuously collects data, and the dynamic environmental compensation module uses the latest environmental parameter mapping item and the environmental parameter time integral item feedback to calculate the latest dynamic environmental compensation factor. The corrected electrical signal is inverted to obtain the gas concentration, and the gas concentration error is fed back to the dynamic environmental compensation and laser 01 control. The weight parameters in each gas gating parameter are continuously optimized through the adaptive update algorithm of online learning and gradient descent.

[0031] This technical solution implements closed-loop feedback control in the data inversion analysis module. First, the signal collected by the photoelectric detector 05 is preprocessed, and then the temperature, humidity and pressure data collected in real time by the environmental sensing module are used to construct a normalized vector. The dynamic environmental compensation factor is calculated through nonlinear mapping and exponential weighted integration of historical concentration errors. The original signal is corrected and the precise gas concentration is inverted. The concentration error is then fed back to the laser 01 to automatically adjust the temperature and current modulation parameters to ensure that the laser output wavelength is always maintained within the preset range, thereby effectively reducing environmental interference and data inversion errors, improving the real-time, stability and accuracy of multi-component gas concentration detection in the heating furnace, improving the overall reliability of the system and reducing maintenance costs.

[0032] It should be noted that in the dynamic environment compensation module, the preset coupling analysis formula takes into account the nonlinear coupling effect between the temperature, pressure and humidity in the heating furnace. The coupling analysis formula based on the radial basis function network maps the normalized environmental parameters to environmental parameter mapping items. The preset coupling analysis formula is: ; Where: is the index of the preset basis function, is the number of preset basis functions, For the The weights of each basis function are calibrated offline. For the The central vector of the basis function is derived from the cluster analysis of historical environmental data. is the normalized environmental parameter vector, , , , At the time The temperature, pressure and humidity data collected in real time by the environmental sensor module, , , They are the temperature reference value, pressure reference value, and humidity reference value of the calibration standard conditions. , , They are the standard deviations of temperature, humidity, and pressure based on historical data statistics. For the The inverse matrix of the covariance matrix of the basis functions is used to quantify the impact of the actual deviation on the mapped value.

[0033] By adopting the coupling analysis formula based on radial basis function network, the temperature, pressure and humidity data collected in real time in the heating furnace are normalized to form the environmental parameter vector , and use the weights of each basis function obtained by offline calibration , center vector and its covariance matrix inverse Perform nonlinear mapping to obtain environmental parameter mapping items This method can accurately capture and quantify the complex nonlinear coupling effects between temperature, pressure and humidity in the heating furnace, and provide an accurate environmental compensation basis for the dynamic environmental compensation module. When environmental fluctuations cause laser output errors and absorption signal drift, the system can adjust the compensation factor in real time, effectively reduce measurement errors, improve the accuracy of gas concentration inversion and the stability of the overall system, and reduce dependence on high-precision sensor performance, thereby providing solid technical support for the long-term stable operation of industrial gas detection systems under high temperature and dynamic conditions.

[0034] It should be noted that in the data inversion analysis module, step 4 closed-loop feedback adjustment of the temperature and current modulation parameters of the laser 01 includes temperature modulation feedback, current modulation feedback and joint control, wherein the temperature modulation feedback uses the PID algorithm to obtain the temperature adjustment amount according to the detected gas concentration error, transmits the temperature adjustment amount to the laser 01, adjusts the operating temperature of the laser 01 chip, and makes the output laser wavelength shift toward the target absorption peak; the current modulation feedback uses the PID control algorithm to obtain the current adjustment amount, transmits the current adjustment amount to the laser 01 to adjust the baseline current and modulation amplitude of the drive circuit, and adjusts the output power and wavelength accordingly; the joint control is based on the decoupling algorithm and the online self-learning strategy to simultaneously adjust the operating temperature of the laser 01 chip and the output power and wavelength of the drive circuit to keep the output stable within the set threshold.

[0035] The environmental dynamic compensation module proposed in the present invention utilizes a dynamic environmental compensation algorithm and closed-loop feedback control technology to realize real-time adaptive correction of laser output errors caused by environmental fluctuations such as temperature, pressure, and humidity in the heating furnace, thereby improving the response speed and anti-interference performance under complex working conditions in the heating furnace.

[0036] Example 2

[0037] Different from Example 1, this embodiment is a specific description of the test for measuring the concentrations of three molecules of CO, N2O, and H2O in an industrial heating furnace based on an industrial gas concentration detection system proposed in Example 1. The test limit temperature is 296, the pressure is one standard atmospheric pressure, and the absorption optical path length is 48.3 meters. The industrial gas concentration detection system proposed in the present invention detects and obtains a direct absorption spectrum, and the CO concentration in the industrial heating furnace at the current measuring point is 600ppd, the N2O concentration is 280ppd, and the H2O concentration is 0.3%. The direct absorption spectra of the three molecules of CO, N2O, and H2O are as follows: Figure 3 As shown, Figure 4 The measured signals of three molecules, CO, N2O and H2O, are shown. Figure 4The three molecules of CO, N2O, and H2O and their second harmonic absorption signals in the infrared band are marked in turn. The temperature, pressure, and humidity collected by the environmental sensor module are 300K, 101.3kPa, and 65%, while the reference values ​​of the system are 296K, 101.3kPa, and 50%, respectively. The standard deviations of temperature, pressure, and humidity are set to =2K, =1kPa and =5%. Based on this, the normalized environment vector is calculated as: =(2,0,3); The environment mapping item is calculated by using the preset radial basis function network coupling analysis formula and offline calibration weights and basis function parameters. =0.85. At the same time, after performing exponential weighted integration on the historical concentration error within the set time window, the feedback integral term is obtained =0.15.

[0038] For CO concentration detection, a linear gating function is used: ; Calculated =0.64.

[0039] Substituting these data into the dynamic environmental compensation formula: ; (Take the overall scaling factor =1), we can calculate =0.946. Without dynamic compensation, the error of CO concentration detected by the system was about 8%. After correction, the compensation factor was used to correct the original optical signal, and the error of CO concentration obtained by inversion was reduced to 1% to 2%, which significantly improved the measurement accuracy. Similar data processing is also applied to the detection of N2O and H2O. By adjusting the parameters of their respective gating functions in a targeted manner, the entire system effectively compensates for the nonlinear deviation caused by environmental factors, achieving high accuracy and robustness in multi-component gas concentration detection.

[0040] In summary, it can be seen from Examples 1 and 2 that the industrial gas concentration detection system proposed in the present invention optimizes the optical structure and strictly limits the parameters of key components, and combines the intelligent control technology based on dynamic environmental compensation and closed-loop feedback control to achieve high-precision, real-time, and stable online detection of CO, N2O, and H2O multi-component gas concentrations in the high-temperature, dynamic and complex environment of an industrial heating furnace. At the same time, it significantly reduces the system's dependence on high-precision sensors and cross-interference between gases, and has high cost-effectiveness and long-term stable operation capabilities.

[0041] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

[0042] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An industrial gas concentration detection system, comprising a transceiver end (101) and a reflector end (102), characterized in that: A laser (01) is arranged in the transceiver end (101), a red light generator is arranged in the laser (01), an off-axis parabolic mirror (02) with a hole in the middle is arranged on one side of the laser (01), a filter (04) is arranged above the off-axis parabolic mirror (02), a photodetector (05) is arranged above the filter (04), a window piece 1 (03) is arranged on the side of the off-axis parabolic mirror (02) away from the laser (01), a window piece 2 (06) is arranged in the reflective end (102), and a full-angle reflector is arranged on one side of the window piece 2 (06) (07), the photoelectric detector (05) is connected to a data inversion analysis module, the data inversion analysis module is connected to a dynamic environment compensation module, the dynamic environment compensation module is connected to an environment sensing module, the dynamic environment compensation module uses the environmental interference data to construct a normalized vector and a normalized deviation of the environmental variable, obtains an environmental parameter mapping item, weightedly accumulates the historical gas concentration inversion error within a set time window, obtains an environmental parameter time integral item, and inputs the two into a dynamic environment compensation formula to dynamically compensate for environmental interference. The dynamic environment compensation formula is: ； Where: is the time variable, is the dynamic environment compensation factor, is the environment parameter mapping item, is the time integral term of the environmental parameter, It is a gating function. For CO, N2O, and H2O gas concentration detection, use the appropriate gating function. is the overall scaling factor.

2. An industrial gas concentration detection system according to claim 1, characterized in that: The optical path between the transceiver end (101) and the reflector end (102) includes: The red indicator light emitted by the red light generator is combined with the infrared light emitted by the laser (01) to form an output light beam, which first passes through the middle opening of the off-axis parabolic mirror (02) and the window piece 1 (03) to enter the gas area to be measured and complete the first absorption; then the laser beam passes through the window piece 2 (06) and is emitted to the full-angle reflector (07), and after being reflected along the original path, it passes through the window piece 2 (06) again to enter the gas area to be measured and undergo a second absorption; the reflected light beam passes through the window piece 1 (03) and is incident on the parabola of the off-axis parabolic mirror (02); its reflected light passes through the filter (04) and is focused onto the light sensitive surface of the photoelectric detector (05); the light signal collected by the photoelectric detector (05) is converted into an electrical signal through photoelectric conversion, and then the data inversion analysis module performs detection electrical signal processing and gas concentration inversion calculation, performs dynamic environmental correction based on a dynamic environmental compensation algorithm, and performs feedback control on the laser (01).

3. An industrial gas concentration detection system according to claim 1, characterized in that: In the dynamic environment compensation module, the gate function used for CO gas concentration detection in the dynamic environment compensation formula uses a linear combination of environmental parameter mapping items and environmental parameter time integral items and limits its output range to [0,1] to smoothly adjust the CO gas concentration detection. The gate function formula used by the dynamic environment compensation formula for CO gas concentration detection is: ； Where: is the gating function value used for CO gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection. The environmental parameters involve temperature, humidity, and pressure. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing CO gas concentration detection.

4. An industrial gas concentration detection system according to claim 3, characterized in that: In the dynamic environment compensation module, the gate function used for N2O gas concentration detection in the dynamic environment compensation formula enables the N2O photoelectric signal to adjust the dynamic environment compensation weight at a set speed when reaching the set critical point, thereby improving the feedback sensitivity when the environment changes suddenly. The gate function formula used for N2O gas concentration detection in the dynamic environment compensation formula is: ； Where: is the gating function value for N2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection. The environmental parameters involve temperature and pressure. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when performing N2O gas concentration detection.

5. An industrial gas concentration detection system according to claim 4, characterized in that: In the dynamic environment compensation module, the gate function used for H2O gas concentration detection in the dynamic environment compensation formula adopts an exponential function to compensate for the error of water vapor concentration caused by humidity changes. The gate function formula used for H2O gas concentration detection in the dynamic environment compensation formula is: ； Where: is the gating function value for H2O gas concentration detection, , They are respectively the environmental parameter mapping item and the environmental parameter time integral item when performing H2O gas concentration detection. The environmental parameters involve humidity. , They are respectively the weight factors of the environmental parameter mapping item and the environmental parameter time integral item when detecting the H2O gas concentration.

6. An industrial gas concentration detection system according to claim 5, characterized in that: In the data inversion analysis module, the process of processing the detection electrical signal, inverting the gas concentration, performing dynamic environment correction based on the dynamic environment compensation algorithm, and feedback controlling the laser (01) includes: Step 1, signal acquisition and preprocessing: the photodetector (05) converts the light signal after two absorptions into an electrical signal, filters the electrical signal, removes background noise and baseline drift; Step 2, calculation of dynamic environmental compensation factor: the environmental sensing module collects the temperature, humidity and pressure in the heating furnace in real time, constructs a normalized environmental state vector, uses a preset coupling analysis formula to perform nonlinear mapping on the environmental parameters, obtains environmental parameter mapping items, and at the same time, performs exponential weighted integration on the historical gas concentration inversion error within the set time window to obtain the environmental parameter time integral item. According to the different gases being measured, the dynamic environmental compensation module uses the corresponding gating function to determine the relative weights between the environmental parameter mapping items and the environmental parameter time integral items, and calculates the current dynamic environmental compensation factor according to the dynamic environmental compensation formula; Step 3, signal correction and concentration inversion: The electrical signal obtained in step 1 is corrected using the dynamic environment compensation factor obtained in step 2. The corrected electrical signal is integrated to extract the integral area of ​​the target gas absorption peak. The current gas concentration is calculated by combining the Beer-Lambert law and the preset inversion formula. Step 4, closed-loop feedback control: compare the current gas concentration obtained in step 3 with the standard gas concentration, calculate the concentration error, feed back the concentration error to the dynamic environment compensation factor through the environmental parameter time integral term, and transmit it to the laser (01) as a feedback signal. The laser (01) uses the error to adjust the modulation parameters of temperature and current to ensure that the output wavelength is maintained within a preset range, optimize the absorption signal and minimize the data inversion error. Step 5, continuous online adaptive update: the environmental sensing module continuously collects data, the dynamic environmental compensation module uses the latest environmental parameter mapping item and the environmental parameter time integral item feedback to calculate the latest dynamic environmental compensation factor, the corrected electrical signal is inverted to obtain the gas concentration, the gas concentration error is fed back to the dynamic environmental compensation and laser (01) control, and the weight parameters in each gas gating parameter are continuously optimized through the adaptive update algorithm of online learning and gradient descent.

7. An industrial gas concentration detection system according to claim 1, characterized in that: In the dynamic environment compensation module, the nonlinear coupling effect between the temperature, pressure and humidity in the heating furnace is considered based on the preset coupling analysis formula. Based on the coupling analysis formula of the radial basis function network, the normalized environmental parameters are mapped into environmental parameter mapping items. The preset coupling analysis formula is: ； Where: is the index of the preset basis function, is the number of preset basis functions, For the The weights of each basis function are calibrated offline. For the The central vector of the basis function is derived from the cluster analysis of historical environmental data. is the normalized environmental parameter vector, , , , At the time The temperature, pressure and humidity data collected in real time by the environmental sensor module, , , They are the temperature reference value, pressure reference value, and humidity reference value of the calibration standard conditions. , , They are the standard deviations of temperature, humidity, and pressure based on historical data statistics. For the The inverse matrix of the covariance matrix of the basis functions is used to quantify the impact of the actual deviation on the mapped value.

8. An industrial gas concentration detection system according to claim 6, characterized in that: In the data inversion analysis module, step 4 closed-loop feedback adjustment of the temperature and current modulation parameters of the laser (01) includes temperature modulation feedback, current modulation feedback and joint control, wherein the temperature modulation feedback uses a PID algorithm to obtain a temperature adjustment amount according to the detected gas concentration error, and transmits the temperature adjustment amount to the laser (01) to adjust the operating temperature of the laser (01) chip so that the output laser wavelength shifts toward the target absorption peak. The current modulation feedback uses a PID control algorithm to obtain a current adjustment amount, and transmits the current adjustment amount to the laser (01) to adjust the baseline current and modulation amplitude of the drive circuit, and adjust the output power and wavelength accordingly. The joint control is based on a decoupling algorithm and an online self-learning strategy to simultaneously adjust the operating temperature of the laser (01) chip and the output power and wavelength of the drive circuit to keep the output stable within a set threshold.

9. An industrial gas concentration detection system according to claim 1, characterized in that: The central opening diameter of the off-axis parabolic mirror (02) is set to be between 3 and 5 mm. The appropriate focal length and curvature are selected according to the optical path length and the expected spot size. The installation angle accuracy is controlled within ±0.1°. Window piece 1 (03) and window piece 2 (06) are both high-temperature resistant windows made of sapphire with a thickness of between 1 and 3 mm. The surface is provided with anti-reflection and heat-resistant coatings. The filter (04) is a mid-infrared filter with a central wavelength of 4.535 μm and a bandwidth of 10 nm. The projection rate in the target band is greater than or equal to 90%, and the optical density in the 2.2 to 2.4 μm out-band area and related interference bands is greater than or equal to 4.

10. An industrial gas concentration detection system according to claim 1, characterized in that: Laser (01) is a mid-infrared quantum cascade laser, which emits 2202.8-2205.6cm after modulation. -1 For mid-infrared lasers, the output power of the red indicator light accounts for 0.5% to 2% of the infrared light output power.

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