Modular single-light-source double-channel CO2 gas concentration measuring device, system and method

Abstract

The invention belongs to the technical field of gas concentration detection, and particularly relates to a modular single-light-source double-channel CO2 gas concentration measuring device, system and method, the device comprises a gas chamber module, an infrared generation module and a detection module, infrared light is emitted through a single infrared light source, and the infrared light is irradiated into gas to be detected in a gas chamber through a beam expander; and detecting the intensity of the infrared light passing through the gas to be detected by using a double-channel detector, and obtaining the CO2 concentration through an inversion calculation formula. The system further comprises an electromagnetic valve used for controlling sampling and processing of gas to be detected, a sampling pump and a control module. The method provided by the invention has high precision, real-time performance and stability, is suitable for long-term stable operation on an industrial site, and helps enterprises to realize a win-win situation of economic benefits and environmental benefits.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas concentration detection, and particularly relates to a modular single-light-source dual-channel CO2 gas concentration measurement device, system, and measurement method. Background Art

[0002] In the key links of environmental monitoring and industrial production, accurately obtaining the concentrations of certain characteristic gas pollutants in waste gas is an important basis for ensuring environmental quality and production safety. Accurately monitoring the dynamic total emissions of carbon dioxide at industrial waste gas discharge ports is particularly important. Currently, CO2 gas detection technologies mainly include gas chromatography, electrochemistry, photoacoustic spectroscopy, and non-dispersive infrared method, etc. Among them, the non-dispersive infrared technology has shown significant advantages in long-term stable operation in industrial sites due to its characteristics such as fast response, high precision, simple instrument structure, and low maintenance cost. This technology utilizes the selective absorption of CO2 on infrared light of a specific wavelength and determines the CO2 concentration by measuring the change in infrared light intensity.

[0003] Although the non-dispersive infrared technology performs well in CO2 gas concentration measurement, the existing measurement devices based on this technology still have some problems. First of all, the attenuation of the light source brightness is a problem that cannot be ignored. It will affect the stability and intensity of infrared light, and thus affect the measurement accuracy. Secondly, the measurement results of the sensor are easily affected by temperature changes, resulting in measurement data drift and reducing the measurement accuracy. In addition, the measurement structure is complex, increasing the maintenance difficulty and cost of the device. Therefore, there is an urgent need in the prior art for a new type of CO2 gas concentration measurement device that can solve problems such as the attenuation of the light source brightness, the drift of the sensor measurement results with temperature changes, and the complex measurement structure. Summary of the Invention

[0004] The purpose of the present invention is to provide a modular single-light-source dual-channel CO2 gas concentration measurement device, system, and measurement method to solve the problems of light source brightness attenuation, drift of sensor measurement results with temperature changes, and complex measurement structure in the existing device for measuring CO2 concentration in gas based on the non-dispersive infrared method.

[0005] The present invention achieves the above purpose through the following technical solutions:

[0006] In the first aspect, the present invention proposes a modular single-light-source dual-channel CO2 gas concentration measurement device, including:

[0007] A gas chamber module, including a gas chamber and a heating element. A conical inner cavity one is provided along the length direction of the gas chamber, and the gas to be measured is introduced into the conical inner cavity one and heated by the heating element;

[0008] The infrared generation module includes a single infrared light source and a beam expander. The infrared light source emits infrared light with a wavelength of 2 - 20 μm, which is irradiated into the first conical inner cavity after passing through the beam expander.

[0009] The detection module includes a dual-channel detector with a measurement channel and a reference channel, which is used to detect the intensity of the infrared light after passing through the gas to be measured. A 4.3 μm filter that matches the characteristic absorption peak of CO2 is provided in the measurement channel, and a 3.95 μm filter that avoids the absorption band of interfering gases is provided in the reference channel.

[0010] Furthermore, an air inlet hole and an air outlet hole are provided on the side of the gas chamber. The gas to be measured is controlled by an electromagnetic valve and a sampling pump, and is injected into the interior of the gas chamber through the air inlet hole. After filling the interior of the gas chamber, it is discharged through the air outlet hole.

[0011] Furthermore, the beam expander consists of a second conical inner cavity, a first lens, and a second lens. The first lens is a convex lens, and the second lens is a concave lens, forming a Galilean beam expander system. The first lens performs primary collimation on the infrared light emitted by the infrared light source, and the second lens performs secondary modulation on the divergence angle. The formed beam expander is used to expand the output spot diameter of the infrared light emitted by the infrared light source and increase the irradiation area.

[0012] Furthermore, the wide-diameter ends of the first conical inner cavity and the second conical inner cavity are aligned, and the infrared light after passing through the beam expander is irradiated into the first conical inner cavity from the wide-diameter end.

[0013] Furthermore, the detection module also includes a detector fixing member. The detector fixing member is made of aerospace aluminum alloy material, and a semiconductor temperature control module is embedded inside. The working temperature of the dual-channel detector is stabilized within the range of ±0.1 °C through the PID algorithm.

[0014] In a second aspect, the present invention proposes a modular single-source dual-channel CO2 gas concentration measurement system, which includes the modular single-source dual-channel CO2 gas concentration measurement device as described above, and also includes an electromagnetic valve and a sampling pump for controlling the sampling and processing of the gas to be measured, and a control module;

[0015] The control module is electrically connected to the control end of the heating element, and is used to control the working power of the heating element by collecting the real-time temperature of the gas chamber, thereby controlling the temperature of the gas chamber;

[0016] The control module is electrically connected to the light source drive circuit board at the drive end of the infrared light source, and the output end of the light source drive circuit board is electrically connected to the input end of the infrared light source;

[0017] The control module is electrically connected to the detector drive circuit board of the dual-channel detector.

[0018] Third aspect, the present invention proposes a method for measuring the CO2 gas concentration, which is implemented based on the above-mentioned modular single-light-source dual-channel CO2 gas concentration measurement system. The method includes the following steps:

[0019] S1. The control module drives the infrared generation module to emit infrared light, which irradiates the gas to be measured in the first conical inner cavity.

[0020] S2. The gas to be measured selectively absorbs the infrared light of a specific wavelength, and the absorbed infrared light is emitted from the gas chamber module and irradiated on the dual-channel detector of the detection module.

[0021] S3. The measurement channel of the dual-channel detector converts the infrared light intensity near 4.3 μm into an electrical signal V1, and the reference channel converts the infrared light intensity near 3.95 μm into an electrical signal V2.

[0022] S4. The control module receives the electrical signals V1 and V2, and calculates the CO2 concentration in the gas to be measured by using the inversion calculation formula.

[0023] Among them, the inversion calculation formula is:

[0024]

[0025] Among them, is the CO2 concentration in the gas to be measured; k and b are inversion coefficients.

[0026] Further, the dual-channel detector is specifically a dual-channel pyroelectric infrared gas sensor.

[0027] Further, the inversion coefficients k and b are determined through the following steps:

[0028] Nitrogen and a CO2 standard gas with a concentration of L are respectively introduced into the gas chamber module.

[0029] Record the original signal sets of the dual-channel pyroelectric infrared gas sensor when nitrogen and the CO2 standard gas are introduced.

[0030] Calculate the original signal means of the measurement channel and the reference channel.

[0031] Calculate the inversion coefficients k and b according to the original signal means, as shown in the following formula:

[0032]

[0033] Among them, and are respectively the original signal means of the measurement channel and the reference channel when nitrogen is introduced, and are respectively the original signal means of the measurement channel and the reference channel when the CO2 standard gas is introduced.

[0034] The beneficial effects of the present invention are as follows:

[0035] The present invention adopts a single light source and a dual-channel pyroelectric infrared gas sensor design, which can effectively reduce the number of optical elements, reduce the structural complexity, and avoid the additional hardware costs brought by multiple light sources. At the same time, the single light source can ensure that the spectral characteristics (wavelength, intensity) of the two channels are exactly the same, eliminating the measurement errors caused by the differences of multiple light sources. Through the differential processing of the dual-channel signals, the environmental interference can be effectively suppressed, and the measurement accuracy and long-term stability can be significantly improved. The use of a beam expander and a conical gas chamber design can effectively enhance the intensity of the infrared light irradiated on the dual-channel pyroelectric infrared gas sensor, uniform the spot distribution, avoid local saturation or signal distortion, and improve the response consistency of the detector. Brief Description of the Drawings

[0036] Figure 1 It is a schematic diagram of the overall structure of the modular single light source dual-channel CO2 gas concentration measurement device provided by the embodiment of the present application;

[0037] Figure 2 It is an exploded structure schematic diagram of the modular single light source dual-channel CO2 gas concentration measurement device provided by the embodiment of the present application;

[0038] Figure 3 It is a schematic diagram of the sectional structure of the modular single light source dual-channel CO2 gas concentration measurement device provided by the embodiment of the present application;

[0039] Figure 4 It is a system structure diagram of the modular single light source dual-channel CO2 gas concentration measurement system provided by the embodiment of the present application;

[0040] Figure 5 It is a schematic flow diagram of a CO2 gas concentration measurement method provided by the embodiment of the present application.

[0041] Figures 1-3 In the figure, 1. Gas chamber module; 2. Infrared generation module; 3. Detection module; 4. Control module; 11. Gas chamber; 12. Air inlet hole; 13. Air outlet hole; 14. Installation port; 15. Cover plate; 16. Heating element; 17. First conical inner cavity; 18. First lens; 21. Beam expander; 22. Fixed plate; 23. Infrared light source; 24. Light source drive circuit board; 25. Second lens; 26. Second conical inner cavity; 31. Detector drive circuit board; 32. Dual-channel detector; 33. Detector fixing part. Detailed Embodiments

[0042] The present application will be further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific embodiments are only used to further illustrate the present application and cannot be construed as limiting the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0043] As Figures 1-3 shown, this embodiment proposes a modular single-light-source dual-channel CO2 gas concentration measurement device, which specifically includes a gas chamber module 1, an infrared generation module 2, and a detection module 3.

[0044] The gas chamber module 1 includes a gas chamber 11 and a heating element 16. A conical inner cavity 17 is provided along the length direction of the gas chamber 11, and the gas to be measured is introduced into the conical inner cavity 17 and heated by the heating element 16; the conical inner cavity 17 is specifically a conical barrel-shaped hollow structure with a smooth inner surface; an air inlet hole 12 and an air outlet hole 13 are opened on one side of the gas chamber 1. The gas to be measured is controlled by an electromagnetic valve and a sampling pump and injected into the interior of the gas chamber 11 through the air inlet hole 12. After filling the interior of the gas chamber 11, it is discharged through the air outlet hole 13. An installation opening 14 is also opened on one side of the gas chamber 1 for installing a cover plate 15. The heating element 16 is provided on the inner side of the cover plate 15 facing the gas chamber 11. The heating element 16 is an electric heating device. The heating element 16 is fixed on the surface of the gas chamber 11 by heating the cover plate 15. The contact surfaces between the heating element 16, the cover plate 15, and the gas chamber 11 are connected by thermal conductive silicone.

[0045] The infrared generation module 2 includes a single infrared light source 23, a beam expander 21, a light source drive circuit board 24, and a fixing plate 22 (for fixing the infrared light source 23). The infrared light source 23 emits infrared light with a wavelength of 2-20 μm, which is irradiated into the conical inner cavity 17 after passing through the beam expander 21; the emitted infrared light passes through the infrared light source fixing plate 22 and enters the incident end of the gas chamber 11 after being processed by the beam expander 21; an installation hole is opened at the central position of the fixing plate 22, and the infrared light source 23 passes through the installation hole and is fixed on the fixing plate 22; the light source drive circuit board 24 is a drive controller for the infrared light source 23; the beam expander 21 is composed of a conical inner cavity 26, a first lens 18, and a second lens 25. The first lens 18 is a convex lens, and the second lens 25 is a concave lens, forming a Galilean beam expander system. The first lens 18 performs primary collimation on the infrared light emitted by the infrared light source 23, and the second lens 25 performs secondary modulation on the divergence angle. The formed beam expander 21 is used to expand the output light spot diameter of the infrared light emitted by the infrared light source 23, increase the irradiation area, and achieve uniform coverage of the cross-section of the gas chamber in the optical path.

[0046] In a specific embodiment, the wide-diameter ends of the first conical inner cavity 17 and the second conical inner cavity 26 are aligned. Among them: the second conical inner cavity 26 serves as an integrated structure of the beam expander 21, and its hollow conical barrel-shaped design (the first conical inner cavity 17 and the second conical inner cavity 26) causes the divergent light beam modulated by the first lens 18 and the second lens 25 to undergo axial diffusion, expanding the spot diameter, and forming a uniform light field distribution at the air chamber inlet end; the infrared light enters the first conical inner cavity 17 through the beam expander 21 from the wide-diameter end, and its tapered barrel-shaped structure focuses the infrared light beam after gas absorption towards the direction of the dual-channel detector 32, converging the spot diameter from the wide-diameter end to the narrow-diameter end, covering the effective photosensitive area of the dual-channel detector 32. This structure can cooperate to improve the uniformity of light intensity distribution, reduce reflection loss, and improve the signal-to-noise ratio of the system.

[0047] The detection module 3 includes a dual-channel detector 32 with a measurement channel and a reference channel, a detector drive circuit board 31, and a detector fixing member 33. The dual-channel detector 32 is used to detect the intensity of the infrared light passing through the gas to be measured; the measurement channel is provided with a 4.3 μm filter that matches the characteristic absorption peak of CO2, and the reference channel is provided with a 3.95 μm filter that avoids the absorption band of interfering gases. The detector fixing member 33 is made of aerospace aluminum alloy material, and a semiconductor temperature control module is embedded inside. The working temperature of the dual-channel detector 32 is stabilized within the range of ±0.1 °C through the PID algorithm; the detector drive circuit board 31 is a drive controller for the dual-channel detector 32.

[0048] It can be understood that this embodiment adopts a single light source and dual-channel detector design, reducing the number of optical elements, simplifying the structure, and reducing the hardware cost; in addition, the infrared light emitted by the infrared light source enters the two detection channels respectively after passing through the beam expander. These two detection channels correspond to two different wavelengths respectively, and are used to measure the absorption of the gas at these two wavelengths. By comparing the signals of these two channels, the concentration of the gas to be measured can be calculated.

[0049] Combined Figure 4 , in a specific embodiment, the present invention also proposes a modular single light source dual-channel CO2 gas concentration measurement system, including the modular single light source dual-channel CO2 gas concentration measurement device as described above, and further including a solenoid valve and a sampling pump for controlling the sampling and processing of the gas to be measured, and a control module 4; the control module 4 is electrically connected to the control end of the heating element 16, and is used to control the working power of the heating element 16 by collecting the real-time temperature of the air chamber 11, thereby controlling the temperature of the air chamber 11; the control module 4 is electrically connected to the drive end light source drive circuit board 24 of the infrared light source 23, and the output end of the light source drive circuit board 24 is electrically connected to the input end of the infrared light source 23; the control module 4 is electrically connected to the detector drive circuit board 31 of the dual-channel detector 32.

[0050] It can be understood that in the above system, the control module 4 is the core control unit of the system, responsible for controlling the driving of the infrared light source 23, the temperature regulation of the heating element 16, and the signal processing of the dual-channel detector 32. The control module 4 is built-in with a variety of adaptive algorithms, which can dynamically adjust the driving power of the infrared light source 23 and compensate in real time for the influence of environmental variables such as pressure, temperature, and humidity on the measurement results. In addition, the solenoid valve and the sampling pump are used to control the sampling and flow of the gas to be measured, ensuring that the gas can stably enter and exit the gas chamber 11.

[0051] Combined with Figure 5 , in a specific embodiment, the present invention also proposes a method for measuring the CO2 gas concentration, which is implemented based on the above-mentioned modular single-light-source dual-channel CO2 gas concentration measurement system. The method includes the following steps:

[0052] S1. The control module 4 drives the infrared generation module 2 to emit infrared light, which irradiates the gas to be measured in the conical inner cavity 17;

[0053] S2. The gas to be measured selectively absorbs the infrared light of a specific wavelength, and the absorbed infrared light is emitted from the gas chamber module 1 and irradiated on the dual-channel detector 32 of the detection module 3;

[0054] S3. The measurement channel of the dual-channel detector 32 converts the infrared light intensity near 4.3 μm into an electrical signal V1, and the reference channel converts the infrared light intensity near 3.95 μm into an electrical signal V2;

[0055] S4. The control module 4 receives the electrical signals Vz and V2, and calculates the CO2 concentration in the gas to be measured by using the inversion calculation formula;

[0056] Wherein, the inversion calculation formula is:

[0057]

[0058] Wherein, is the CO2 concentration in the gas to be measured; k and b are inversion coefficients.

[0059] In a specific embodiment, the dual-channel detector 32 is specifically a dual-channel pyroelectric infrared gas sensor. More specifically, the inversion coefficients k and b are determined through the following steps: Nitrogen (CO2 concentration is 0) and CO2 standard gas with a concentration of L are respectively introduced into the gas chamber module 1; Record the original signal sets of the dual-channel pyroelectric infrared gas sensor when nitrogen and CO2 standard gas are introduced (the original signal is the sensor output electrical signal that has a significant correlation with the change in CO2 concentration, such as: voltage, current, etc.); Calculate the mean values of the original signals of the measurement channel and the reference channel; Calculate the inversion coefficients k and b according to the mean values of the original signals, as shown in the following formula:

[0060]

[0061] Among them, and are respectively the original signal means of the measurement channel and the reference channel when nitrogen is introduced. and are respectively the original signal means of the measurement channel and the reference channel when the CO2 standard gas is introduced.

[0062] Exemplarily, record the group of original signals output by the dual-channel pyroelectric infrared gas sensor within M minutes; the set of original signals output by the measurement channel when nitrogen is introduced is denoted as X 0_W , and the set of original signals output by the reference channel is denoted as X 0_A ; when the CO2 standard gas with a concentration of L is introduced, the set of original signals output by the measurement channel is denoted as X L_W , and the set of original signals output by the reference channel is denoted as X L_A , where n is the number of original data within M minutes.

[0063] X 0_W ={x 0_W1 , x 0_W2 , x 0_W3 , …, x 0_Wn}

[0064] X 0_A ={x 0_A1 , x 0_A2 , x 0_A3 , …, x 0_An}

[0065] X L_W ={x L_W1 , x L_W2 , x L_W3 , …, x L_Wn}

[0066] X L_A ={x L_A1 , x L_A2 , x L_A3 , …, x L_An}

[0067] Furthermore, calculate the original signal means of the measurement channel and the reference channel output within M minutes.

[0068] Among them are respectively the original signal mean of the measurement channel and the original signal mean of the reference signal.

[0069]

[0070] Furthermore, the calculation method of the inversion coefficients k and b in the inversion calculation formula is:

[0071]

[0072] The above embodiments are only used to illustrate the technical solutions of the present application, rather than limiting them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A modular single-light-source dual-channel CO2 gas concentration measurement device, characterized in that Comprising: A gas chamber module (1), including a gas chamber (11) and a heating element (16). A conical inner cavity one (17) is provided along the length direction inside the gas chamber (11). The gas to be measured is introduced into the conical inner cavity one (17) and heated by the heating element (16). An infrared generation module (2), including a single infrared light source (23) and a beam expander (21). The infrared light source (23) emits infrared light with a wavelength of 2 - 20 μm, which is irradiated into the conical inner cavity one (17) after passing through the beam expander (21). A detection module (3), including a dual-channel detector (32) having a measurement channel and a reference channel, for detecting the intensity of the infrared light after passing through the gas to be measured. A 4.3 μm filter matching the characteristic absorption peak of CO2 is provided in the measurement channel, and a 3.95 μm filter avoiding the absorption band of interfering gases is provided in the reference channel.

2. The modular single-light-source dual-channel CO2 gas concentration measuring device according to claim 1, characterized in that, An air inlet hole (12) and an air outlet hole (13) are provided on the side of the gas chamber (1). The gas to be measured is controlled by an electromagnetic valve and a sampling pump, and is injected into the interior of the gas chamber (11) through the air inlet hole (12). After filling the interior of the gas chamber (11), it is discharged through the air outlet hole (13).

3. The modular single-light-source dual-channel CO2 gas concentration measuring device according to claim 1, wherein The beam expander (21) is composed of a conical inner cavity two (26), a first lens (18), and a second lens (25). The first lens (18) is a convex lens, and the second lens (25) is a concave lens, forming a Galilean beam expander system. The first lens (18) performs primary collimation on the infrared light emitted by the infrared light source (23), and the second lens (25) performs secondary modulation on the divergence angle. The formed beam expander (21) is used to expand the output spot diameter of the infrared light emitted by the infrared light source (23) and increase the irradiation area.

4. The modular single-light-source dual-channel CO2 gas concentration measuring device according to claim 3, characterized in that, The wide-diameter ends of the conical inner cavity one (17) and the conical inner cavity two (26) are aligned, and the infrared light after passing through the beam expander (21) is irradiated into the conical inner cavity one (17) from the wide-diameter end.

5. The modular single-light-source dual-channel CO2 gas concentration measurement device according to claim 1, characterized in that The detection module (3) further includes the detector fixing member (33). The detector fixing member (33) is made of aerospace aluminum alloy material, and a semiconductor temperature control module is embedded inside. The working temperature of the dual-channel detector (32) is stabilized within the range of ±0.1 °C through the PID algorithm.

6. A modular single-light-source dual-channel CO2 gas concentration measurement system, characterized in that, Including the modular single-light-source dual-channel CO2 gas concentration measurement device according to claim 1, further including an electromagnetic valve and a sampling pump for controlling the sampling and processing of the gas to be measured, and a control module (4); The control module (4) is electrically connected to the control end of the heating element (16), and is used to control the working power of the heating element (16) by collecting the real-time temperature of the gas chamber (11), thereby controlling the temperature of the gas chamber (11). The control module (4) is electrically connected to the light source driving circuit board (24) at the driving end of the infrared light source (23), and the output end of the light source driving circuit board (24) is electrically connected to the input end of the infrared light source (23). The control module (4) is electrically connected to the detector driving circuit board (31) of the dual-channel detector (32).

7. A method for measuring the concentration of CO2 gas, characterized in that, Based on the modular single-light-source dual-channel CO2 gas concentration measurement system according to claim 6, the method includes the following steps: S1. The control module (4) drives the infrared emission module (2) to emit infrared light, which irradiates the gas to be measured in the first conical inner cavity (17); S2. The gas to be measured selectively absorbs infrared light of a specific wavelength, and the absorbed infrared light is emitted from the gas chamber module (1) and irradiates on the dual-channel detector (32) of the detection module (3); S3. The measurement channel of the dual-channel detector (32) converts the infrared light intensity near 4.3 μm into an electrical signal V1, and the reference channel converts the infrared light intensity near 3.95 μm into an electrical signal V2; S4. The control module (4) receives the electrical signals V1 and V2, and calculates the CO2 concentration in the gas to be measured by using the inversion calculation formula; Among them, the inversion calculation formula is: where, is the CO2 concentration in the gas to be measured; k and b are inversion coefficients.

8. The method for measuring the CO2 gas concentration according to claim 7, wherein The dual-channel detector (32) is specifically a dual-channel pyroelectric infrared gas sensor.

9. A method for measuring the concentration of CO2 gas according to claim 8, characterized in that, The inversion coefficients k and b are determined through the following steps: Nitrogen and a CO2 standard gas with a concentration of L are respectively introduced into the gas chamber module (1); Record the original signal sets of the dual-channel pyroelectric infrared gas sensor when nitrogen and the CO2 standard gas are introduced; Calculate the mean values of the original signals of the measurement channel and the reference channel; Calculate the inversion coefficients k and b according to the mean values of the original signals, as shown in the following formula: Wherein, and are respectively the original signal means of the measurement channel and the reference channel when nitrogen is introduced. and are respectively the original signal means of the measurement channel and the reference channel when CO2 standard gas is introduced.

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