Low-drift infrared gas detection device and detection method thereof
By adopting a narrowband filter detector with consistent characteristics in the infrared gas detection device, the problems of large drift and poor selectivity in the prior art are solved, and gas concentration measurement with low drift and high selectivity are achieved.
Patent Information
- Application Number
- CN202311422946.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-05-02
AI Technical Summary
In the existing infrared gas detection devices, there are large differences in the spectral response and drift characteristics of the reference and measurement channels, resulting in large drifts of measurement results, and the reference channels are easily affected by other gases, with poor selectivity and inaccurate measurements.
A low-drift infrared gas detection device is designed, and two narrowband filter detectors with consistent characteristics are used to design the optical path, gas path and structure to achieve the detection signal comparison measurement, reduce drift and improve selectivity.
Low drift and high selectivity are achieved, ensuring the accuracy and stability of gas concentration measurements.
Smart Images
Figure CN119915727A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of detection technology, and in particular to a low-drift infrared gas detection device and a detection method thereof. Background Art
[0002] Infrared gas analysis technology is a widely used technology that performs quantitative gas detection based on the characteristic absorption characteristics of gas molecules to infrared light and follows the Lambert-Beer law.
[0003] Infrared gas analysis technology mainly uses non-dispersive infrared (NDIR) absorption spectroscopy. With the research and development of new materials and new processes, the new NDIR gas detection technology that uses a broadband electrically modulated blackbody radiation infrared light source and a solid-state detector that senses micro-thermal changes has become a research hotspot. In the prior art, the device includes: an infrared light source assembly, an air chamber assembly, a detector assembly, and a temperature control assembly. The infrared light source assembly is used to generate wide-spectrum infrared; the air chamber assembly is used for sample gas circulation; the detector assembly is used for the light intensity of the light source radiation after being absorbed by the sample gas through the air chamber, and the temperature control assembly is used to provide a stable temperature environment for the detection device.
[0004] Disadvantages of the prior art: The detection device of the prior art uses two detectors with different characteristics, specifically detectors using narrow-band filters of different wavelengths, which are located at the same end of the gas chamber and are used for reference and measurement respectively. Due to the large differences in the spectral response and drift characteristics of the reference and measurement channels, the measurement results drift greatly, and the reference channel is easily affected by other gases, resulting in poor selectivity and inaccurate measurement.
[0005] Therefore, as a technical improvement, the applicant specially applies for this invention. Summary of the invention
[0006] In order to solve the above-mentioned problems in the prior art, the present invention provides a low-drift infrared gas detection device which can improve the above-mentioned deficiencies.
[0007] The present invention relates to a low-drift infrared gas detection device, comprising an infrared light source component, an air chamber component, a detector component and a signal processing component; the infrared light source component, the air chamber component and the detector component are arranged adjacent to each other in sequence, the infrared light source component comprises a light source seat, on which a light source, a beam splitter, a first detector and a first window piece are arranged; the air chamber component comprises an air chamber and an air chamber seat arranged at both ends of the air chamber; a second window piece is arranged in the detector component; one end of the air chamber is connected to the first window piece, and the other end is connected to the second window piece; the detector component comprises a detector seat, on which a second window piece, a second detector and a second temperature sensor are arranged; the first detector and the second detector use narrow-band filters with the same wavelength, and have consistent spectral responses and drift characteristics; the signal processing component is arranged on the light source seat and the air chamber seat.
[0008] Furthermore, both ends of the air chamber are connected with air inlets.
[0009] Furthermore, heating components are provided on both the light source seat and the detector seat.
[0010] Furthermore, a first temperature sensor is disposed on the first detector.
[0011] The present scheme also provides a detection method for a low-drift infrared gas detection device, comprising the following steps: a. dividing the infrared light radiated by the light source into two beams; b. then passing the infrared light through a first detector and a second detector respectively, performing signal detection respectively, comparing the signals of the two detectors, establishing a relationship between the gas concentration and the comparison signal, and thereby measuring the gas concentration.
[0012] Furthermore, the derivation process is as follows: assume that the light source radiates infrared light I0, the concentration of the gas to be measured c, the characteristic absorption coefficient k, and the effective optical path L of the gas chamber;
[0013] The light source radiates infrared light I0, which is split into two beams: reflected light R1I0 and direct light R2I0. The reflected light reaches the first detector without attenuation, and the direct light reaches the second detector after passing through the gas chamber containing the gas to be measured. According to the Lambert-Beer law, the infrared light reaching the second detector is expressed as R2I0e -kcL ;
[0014] The response characteristics of the first and second detectors are D1 and D2 respectively. Considering the system factors α such as the window, the comparison signal of the response signals of the first and second detectors can be expressed as:
[0015]
[0016] For the determined system, α, R1, R2, and L are determined by structural parameters and are constants; the coefficient k is related to the type of gas to be measured and is a constant; by selecting the first and second detectors with consistent characteristics, the ratio of D1 and D2 is also a constant.
[0017] Advantages of the invention: This patent proposes an infrared gas detection device, which adopts a new optical path, gas path and structural design, two detectors with consistent characteristics, and compares and measures the detector signals to achieve low drift and selectivity of the detection device; the measurement method implemented by the device has good selectivity and accurate measurement. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is a schematic diagram of the structure of the present invention.
[0019] Illustration: 1 light source seat, 2 light source, 3 beam splitter, 4 first detector, 5 first temperature sensor, 6 signal processing component, 8 first window, 9 gas chamber seat, 10 gas chamber, 12 detector base, 13 second window, 14 second detector, 15 second temperature sensor, 16 heater assembly, 17 O-ring, 18 air inlet. DETAILED DESCRIPTION
[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.
[0021] like Figure 1As shown, the present invention relates to a low-drift infrared gas detection device, including an infrared light source component, an air chamber component, a detector component and a signal processing component; the infrared light source component, the air chamber component and the detector component are arranged adjacent to each other in sequence, and the components are sealed by O-rings 17, and locked by fasteners, and can be assembled and disassembled. When a fault or contamination occurs, the corresponding components can be replaced or cleaned, which is convenient for maintenance. The infrared light source component includes a light source seat 1, and a light source 2, a beam splitter 3, a first detector 4 and a first window sheet 8 are arranged on the smooth seat. The light source, the beam splitter and the first window sheet are fixed to the light source seat by bonding and sealing, so as to achieve isolation between the light source and the environment, and between the light source and the sample gas. The infrared light source component is used to generate infrared light, split light, and detect reflected light beams, wherein the beam splitter adopts a reflective straight-through beam splitter, and the beam splitter is coated with a metal film, so that the beam splitting efficiency is high and the beam splitting light performance is stable and consistent. A conical structure is arranged in the detector seat, which has a light convergence effect and improves the light utilization rate; a detector with a narrow-band filter is adopted, and the filter can correspond to the characteristic absorption spectrum of the gas to be measured through the spectrum. The light source uses a MEMS wide-spectrum electrically modulated infrared light source, which has a gold-plated reflective cup, has the function of collimating and improving the effective radiation energy, and is sealed with inert gas to stabilize the radiation and extend the service life; the gas chamber assembly includes an air chamber 10 and a gas chamber seat 11 arranged at both ends of the gas chamber, and the gas chamber assembly is used for the circulation of sample gas and absorption of infrared spectrum; a second window piece 13 is arranged in the detector assembly; one end of the gas chamber is connected to the first window piece, and the other end is connected to the second window piece; the signal processing component 6 is arranged on the light source seat and the gas chamber seat, and it is used for light source driving, temperature control and infrared absorption signal detection and processing.
[0022] As a technical improvement, both ends of the gas chamber are connected with air inlets 18, and a stainless steel tube of a certain length or a gold-plated tube gas chamber with an inner wall is used to adapt to the corrosive sample gas environment.
[0023] As a technical improvement, a heating assembly 16 is provided on both the light source seat and the detector seat. The heating assembly on the light source seat provides a suitable and stable temperature environment for the light source, and the heating assembly on the detector seat provides a suitable and stable temperature environment for the detector.
[0024] As a technical improvement, a second detector 14 and a second temperature sensor 15 are arranged on the detector. The spectral response and drift characteristics of the second detector are consistent with those of the first detector. The second temperature sensor is arranged adjacent to the second detector to quickly detect the temperature of the second detector in the detector assembly. Similarly, a first temperature sensor 5 is arranged on the first detector to quickly detect the temperature of the first detector in the light source assembly.
[0025] The present scheme also provides a detection method for a low-drift infrared gas detection device, comprising the following steps: a. dividing the infrared light radiated by the light source into two beams; b. then passing the infrared light through a first detector and a second detector respectively, performing signal detection respectively, comparing the signals of the two detectors, establishing a relationship between the gas concentration and the comparison signal, and thereby measuring the gas concentration.
[0026] Furthermore, the derivation process is as follows: assume that the light source radiates infrared light I0, the concentration of the gas to be measured c, the characteristic absorption coefficient k, and the effective optical path L of the gas chamber;
[0027] Among them, the light source radiates infrared light I0, which is split into two beams of reflected light R1I0 and direct light R2I0. The reflected light reaches the first detector without attenuation, and the direct light reaches the second detector after passing through the gas chamber containing the gas to be measured. According to the Lambert-Beer law, the infrared light reaching the second detector is expressed as R2I0e -kcL ;
[0028] The response characteristics of the first and second detectors are D1 and D2 respectively. Considering the system factors α such as the window, the comparison signal of the response signals of the first and second detectors can be expressed as:
[0029]
[0030] For the determined system, α, R1, R2, and L are determined by structural parameters and are constants; the coefficient k is related to the type of gas to be measured and is a constant; by selecting the first and second detectors with consistent characteristics, the ratio of D1 and D2 is also a constant.
[0031] Specific consideration and analysis show that the change of the comparison signal S is almost only related to the change of the concentration c of the gas to be measured, which not only eliminates the drift of the detection result caused by the drift of the infrared light source I0, but also greatly suppresses the drift of the detection result caused by the drift of a single detector, thereby realizing low-drift infrared gas detection. At the same time, it avoids the cross-interference of the reference signal by the background gas due to the use of detectors with different wavelengths as the reference signal, and has good gas detection selectivity.
Claims
1. A low drift infrared gas detection device, characterized in that: The invention comprises an infrared light source component, an air chamber component, a detector component and a signal processing component; the infrared light source component, the air chamber component and the detector component are arranged adjacent to each other in sequence; the infrared light source component comprises a light source seat, on which a light source, a beam splitter, a first detector and a first window piece are arranged; the air chamber component comprises an air chamber and an air chamber seat arranged at both ends of the air chamber; one end of the air chamber is connected to the first window piece, and the other end is connected to the second window piece; the detector component comprises a detector seat, on which a second window piece, a second detector and a second temperature sensor are arranged; the first detector and the second detector have the same characteristics; the signal processing component is arranged on the light source seat and the air chamber seat.
2. A low drift infrared gas detection device according to claim 1, characterized in that: Both ends of the air chamber are connected with air inlets.
3. A low drift infrared gas detection device according to claim 1, characterized in that: The light source seat and the detector seat are both provided with heating components.
4. A low drift infrared gas detection device according to claim 1, characterized in that: The first detector is provided with a first temperature sensor.
5. A low drift infrared gas detection device according to claim 1, characterized in that: The first detector and the second detector use narrow-band filters with the same wavelength, and have consistent spectral response and drift characteristics.
6. A detection method using the low-drift infrared gas detection device according to any one of claims 1 to 5, characterized in that: The following steps are involved: a. The infrared light radiated by the light source is divided into two beams, and b. The infrared light is then passed through the first detector and the second detector respectively for signal detection. The signals of the first and second detectors are compared to establish a relationship between the gas concentration and the comparison signal, thereby measuring the gas concentration.
7. The detection method according to claim 6, characterized in that: The derivation process is as follows: set the infrared light radiated by the light source I0, the concentration of the gas to be measured c, the characteristic absorption coefficient k, and the effective optical path of the gas chamber L; Among them, the light source radiates infrared light I0, which is split into two beams of reflected light R1I0 and direct light R2I0. The reflected light reaches the first detector without attenuation, and the direct light reaches the second detector after passing through the gas chamber containing the gas to be measured. According to the Lambert-Beer law, the infrared light reaching the second detector is expressed as R2I0e -kcL ; The response characteristics of the first and second detectors are D1 and D2 respectively. Considering the system factors α such as the window, the comparison signal of the response signals of the first and second detectors can be expressed as: For the determined system, α, R1, R2, and L are determined by structural parameters and are constants; the coefficient k is related to the type of gas to be measured and is a constant; by selecting the first and second detectors with consistent characteristics, the ratio of D1 and D2 is also a constant.