A multi-component wide-range gas analyzer and gas analysis method

Abstract

The present invention provides a multi-component wide-range gas analyzer and a gas analysis method, belonging to the technical field of gas composition analysis. The gas analyzer comprises a gas chamber cavity, a light source module, a multi-component thermopile or pyroelectric infrared detector and a micro-flow infrared detector. The gas chamber cavity comprises at least one measurement channel; the light source module is arranged upstream of the gas chamber cavity; the multi-component thermopile or pyroelectric infrared detector and the micro-flow infrared detector are used to receive irradiation light emitted by the light source module and absorbed by the measured gas, the micro-flow infrared detector is located downstream of the gas chamber cavity, and the multi-component thermopile or pyroelectric infrared detector is located on the side wall of the gas analyzer. The gas analyzer integrates a low-cost multi-component thermopile or pyroelectric infrared detector and a micro-flow infrared detector capable of measuring low-concentration gas in one gas chamber cavity, thereby realizing simultaneous measurement of multi-component gases, reducing the cost and volume of the gas analyzer while taking into account high-precision measurement of low-concentration gas.

Description

Technical Field

[0001] The present invention relates to the technical field of gas composition analysis, and in particular to a multi-component wide-range gas analyzer and a gas analysis method. Background Art

[0002] With the rapid development of the automotive industry, vehicle exhaust has become a significant source of air pollution, and my country's vehicle exhaust emission standards have been continuously tightened. From 2001 to 2020, my country's emission standards were upgraded from National I to National VI. In May 2019, the Ministry of Ecology and Environment and the State Administration for Market Regulation promulgated and implemented new regulations for vehicle exhaust emission testing, including the "Emission Limits and Measurement Methods of Pollutants from Diesel Vehicles (Free Acceleration Method and Loaded Deceleration Method)" (GB3847-2018) and the "Emission Limits and Measurement Methods of Pollutants from Gasoline Vehicles (Dual Idle Method and Simple Operating Condition Method)" (GB18285-2018). This series of standards imposes stricter requirements on vehicle exhaust pollutant emissions and further lowers the emission limits. To meet the new emission standards, automobile manufacturers must strengthen the testing and control of engine pollutant emissions.

[0003] With the development of detector and electronic technologies, infrared (NDIR) gas detection technology has rapidly expanded. This is primarily due to the use of new infrared detectors and electrically modulated light sources, as well as the adoption of low-power embedded systems in instrument circuits. These instruments offer unparalleled advantages in size, power consumption, performance, and price compared to previous instruments. Based on the different detection principles, NDIR infrared gas sensing technology can be divided into two types: non-dispersive infrared gas detectors that use thermopiles or pyroelectric principles, and non-dispersive infrared gas detectors that use pneumatic detection technology.

[0004] Non-dispersive infrared gas detectors using thermopile or pyroelectric principles can simultaneously measure CO, CO2, and HC in exhaust gas analyzers, as well as high-concentration CO, CO2, and CH4 in the coal chemical and metallurgical industries. However, in low-concentration SO2, NO, CO, and CO2 monitoring scenarios, gas detectors using this principle have weak infrared absorption and may face interference from high-concentration CO2 and H2O gases. For accurate measurement, more sensitive non-dispersive infrared gas detectors using pneumatic detection technology are required, which can minimize interference. Based on the detection method, pneumatic detection technologies are categorized as condense microphones and micro-flow.

[0005] In patent document JPH07198609A, Horiba Corporation of Japan discloses a gas analyzer comprising a light source, a measurement chamber, and a multi-component pyroelectric detector. The multi-component pyroelectric detector comprises multiple light detection units. The detector can simultaneously measure the concentrations of HC, CO, and CO₂ in exhaust gas based on the light signals detected by each unit. Although its structure is simple and cost-effective, the pyroelectric detector cannot accurately monitor low concentrations of NO in exhaust gas because NO is susceptible to interference from moisture within its infrared absorption spectrum and has a weak infrared absorption rate.

[0006] In patent document US5055688A, German Hartmann & Braun company disclosed an infrared gas analyzer, which includes two measuring gas chambers and reference gas chambers arranged side by side. A plurality of microphonic infrared detectors are arranged in sequence downstream of the two gas chamber cavities. A window is provided on the upstream microphonic infrared detector to allow light to pass through the upstream gas detector to the downstream gas detector. A filter is provided between two adjacent microphonic infrared detectors. Each microphonic infrared detector measures the concentration of a gas and can be used to measure the concentration of gases such as CO, CO2, HC and even NO in exhaust gas. Although it can realize multi-component wide-range gas concentration measurement, it contains multiple independent pneumatic detectors, resulting in the exhaust gas analyzer being expensive and bulky. In addition, the use of thin film capacitor microphonic detectors makes the instrument very sensitive to vibration, which is not suitable for portable measurement of exhaust gas and has a high production cost.

[0007] In patent document US5572032A, Japan's Horiba Corporation discloses a gas analyzer including two light sources, two measuring cells, and four detectors. A rotary valve alternately switches the sample gas and reference gas between the two measuring cells of the analyzer. Two detectors are provided on either side of each measuring cell, and light from the measuring cell is transmitted to the two detectors via a semi-transparent, semi-reflective beam splitter. Although the beam splitter enables simultaneous detection of four gases and eliminates long-term drift, the dual light sources, dual gas chambers, and four detectors result in a complex structure and high cost. In addition, the replacement of the reference gas and the measured gas takes time, resulting in a slow response speed of the gas analyzer.

[0008] In patent document US6166383A, the German company Siemens discloses an infrared gas analyzer comprising a light source and multiple gas chambers arranged in series downstream of the light source. The light beam emitted by the light source continuously passes through the multiple gas chambers. The first gas chamber has a shorter gas chamber length, and two micro-flow infrared detectors are arranged downstream of it in sequence to measure CO and CO2 in the exhaust gas, respectively. The second gas chamber is located downstream of the two micro-flow infrared detectors in the first gas chamber in the direction of the light beam. The gas chamber length of the second gas chamber is longer to ensure that the light signal detected by the micro-flow infrared detector is fully absorbed by the NO in the exhaust gas. Two micro-flow infrared detectors are arranged on either side of the second gas chamber to measure NO and HC in the exhaust gas, respectively. The exhaust gas analyzer disclosed in the patent can achieve multi-component gas concentration measurement over a wide range, but its inclusion of multiple independent pneumatic detectors makes the exhaust gas analyzer expensive and bulky.

[0009] Major international exhaust gas sensor technology manufacturers include Horiba, Hartmann & Braun, and Siemens. Most Chinese exhaust gas analyzer manufacturers use imported optical platforms (NDIR infrared three-gas detectors) for assembly. According to new regulations for vehicle exhaust emissions testing, diesel and gasoline vehicle inspection stations must equip exhaust gas analyzers with fast-response optical NOx gas sensors. Existing technology typically uses a thermopile or pyroelectric three-component CO, CO2, and HC optical platform in series with a microflow infrared or ultraviolet optical NOx sensor. This is not only costly but also reduces measurement response speed. By sharing a common infrared light source and infrared gas chamber, using a pyroelectric or thermopile for traditional three-component measurement and a microflow infrared detector for NOx measurement on a single analyzer, performance is improved (using the same light source and gas chamber), cost is reduced (omitting the optical and gas chamber), and measurement response speed is also increased. Therefore, the development of new domestically produced multi-component, wide-range exhaust gas analyzers that meet the emission limits of the China VI standard is crucial.

[0010] In this background technology, only the application scenario of exhaust emission monitoring is used as an example. In fact, there is no limitation to this. The gas analyzer and gas analysis method disclosed in this application can be applied to application scenarios such as CEMS flue gas emission continuous monitoring, combustion efficiency monitoring, coal mill monitoring, and cement kiln process monitoring. Summary of the Invention

[0011] In view of this, an embodiment of the present invention integrates a multi-component thermopile or pyroelectric infrared detector based on the applicant's patent document CN107389585B, and uses a multi-component pyroelectric or thermopile infrared detector on an analyzer to achieve traditional three-component measurement. At the same time, a microflow infrared detector is set to achieve low-concentration gas measurement. The two detectors share a gas chamber and a light source, providing a high-performance, fast-response, low-cost, small-sized, multi-component wide-range gas analyzer and gas analysis method that can simultaneously measure multiple gas components, thereby overcoming the technical problems of high cost and low response speed of existing infrared gas analyzers that, based on a multi-component thermopile or pyroelectric infrared detector, connect a microflow infrared or ultraviolet optical NO sensor in series.

[0012] In a first aspect, an embodiment of the present invention provides a multi-component wide-range gas analyzer, comprising:

[0013] The gas chamber cavity comprises at least one measuring channel, and the measuring channel is used to be filled with the gas to be measured;

[0014] A light source module is provided upstream of the gas chamber cavity and is used to emit illumination light containing an absorption band of the gas to be measured;

[0015] Multi-component thermopile or pyroelectric infrared detector and micro-flow infrared detector, used to receive the irradiation light emitted by the light source module and absorbed by the gas to be measured;

[0016] The micro-flow infrared detector is located downstream of the gas chamber cavity, and the multi-component thermopile or pyroelectric infrared detector is located on the side wall of the multi-component wide-range gas analyzer.

[0017] The multi-component wide-range gas analyzer further includes a reflecting device for reflecting the irradiation light emitted by the light source module and absorbed by the measured gas so as to be received and detected by the multi-component thermopile or pyroelectric infrared detector.

[0018] The center of the reflecting device and the center of the multi-component thermopile or the pyroelectric infrared detector are located on the same vertical line, and a certain angle is formed between the reflecting device and the horizontal plate.

[0019] A light-blocking sleeve is provided on the multi-component thermopile or the pyroelectric infrared detector, and a light-through hole is provided on the light-blocking sleeve.

[0020] The size of the light hole is adapted to the detection surface of the multi-component thermopile or pyroelectric infrared detector, and the center of the detection surface of the multi-component thermopile or pyroelectric infrared detector coincides with the center of the light hole. Therefore, by adjusting the thickness of the light shielding sleeve, the angle of light entering the multi-component thermopile or pyroelectric infrared detector can be controlled, so that the light reflected by the reflecting device can enter the multi-component thermopile or pyroelectric infrared detector at the optimal angle, thereby reducing the interference of light entering at other angles on the multi-component thermopile or pyroelectric infrared detector.

[0021] By consulting the data sheet, the optimal sensing angle α and detection surface diameter D of the multi-component thermopile or pyroelectric infrared detector can be obtained. The thickness H of the light-blocking sleeve can be calculated according to the formula H=D / 2tanα / 2. The thickness of the light-blocking sleeve can meet the requirements within the range of 95%H to 105%H.

[0022] A partition is provided along the central axis of the air chamber cavity to divide the air chamber cavity into a measurement channel and a reference channel of the same size and shape.

[0023] An adjustment plate is movably connected between the air chamber cavity and the micro-flow infrared detector, and an adjustment hole for adjusting the optical signals received by the micro-flow infrared detector from the measurement channel and the reference channel is provided in the middle of the adjustment plate.

[0024] The adjustment board adjusts the optical signal through the following steps:

[0025] S1: Introduce a gas with the same composition and concentration into the measurement channel and the reference channel, such as pure N2;

[0026] S2: Use the microfluidic infrared detector to detect the light intensity received from the measurement channel and the reference channel respectively, and record them as M and R respectively, and determine whether M and R are equal;

[0027] S3: When M≠R, the light intensity received by the microflow infrared detector from the measurement channel and the reference channel is equal by moving the adjustment plate up and down. At this time, fixing the position of the adjustment plate can eliminate the measurement error caused by the structural difference between the two channels and the setting of the reflection device. When M=R, there is no need to move the position of the adjustment plate.

[0028] The optical signal adjustment by the adjustment board also includes the following steps:

[0029] When M<R, the adjustment plate can be moved upward to allow more light to pass through the adjustment hole from the measurement channel to reach the microflow infrared detector. The adjustment plate blocks more light passing through the reference channel, allowing less light to pass through the adjustment hole from the reference channel to reach the microflow infrared detector, until M=R.

[0030] When M>R, the adjustment plate can be moved downward to allow more light to pass through the adjustment hole from the reference channel to reach the microflow infrared detector. The adjustment plate blocks more light passing through the measurement channel, allowing less light to pass through the adjustment hole from the measurement channel to reach the microflow infrared detector, until M=R.

[0031] The multi-component wide-range gas analyzer also includes a detection cavity, the front end of which is connected to the end of the gas chamber cavity, and a transverse plate is provided along the extension line of the partition plate, the transverse plate divides the detection cavity into a first channel and a second channel, the first channel is arranged opposite to the measurement channel, and the second channel is arranged opposite to the reference channel;

[0032] The reflection device is arranged in the first channel of the detection cavity;

[0033] The multi-component thermopile or pyroelectric infrared detector is arranged in the first channel and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device;

[0034] The micro-flow infrared detector is arranged at the end of the detection cavity, and is used for receiving and detecting the light intensity in the first channel and the second channel respectively.

[0035] The reflecting device is arranged in the measuring channel of the air chamber cavity and is located on the partition;

[0036] The multi-component thermopile or pyroelectric infrared detector is arranged in the measuring channel and opposite to the reflecting device, and is used for receiving and detecting the intensity of light reflected by the reflecting device.

[0037] The multi-component wide-range gas analyzer further includes a detection cavity, the front end of which is connected to the end of the gas chamber cavity;

[0038] The reflection device is arranged in the detection cavity;

[0039] The multi-component thermopile or pyroelectric infrared detector is arranged inside the detection cavity and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device;

[0040] The micro-flow infrared detector is arranged at the end of the detection cavity and is used to receive and detect the light intensity in the first channel and the second channel respectively.

[0041] a reflector disposed in the measuring channel of the air chamber cavity and located on the partition;

[0042] The multi-component thermopile or pyroelectric infrared detector is arranged in the measuring channel and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device.

[0043] In a second aspect, an embodiment of the present invention provides a gas analysis method, which is applied to the multi-component wide-range gas analyzer provided in the first aspect of the present invention. The gas analysis method includes the following steps:

[0044] S1. Fill the measurement channel with a gas of known concentration to be measured, and fill the reference channel with a reference gas. The infrared light emitted by the light source module is emitted into the measurement channel and the reference channel in a time-sharing manner.

[0045] S2. The multi-component thermopile or pyroelectric infrared detector includes a reference probe and multiple measurement probes. Each probe of the multi-component thermopile or pyroelectric infrared detector synchronously detects the optical signal of the measurement channel and calculates the ratio of the output signal intensity of each measurement probe to that of the reference probe.

[0046] S3, respectively fitting the relationship between the output signal intensity ratio of each measuring detector head and the reference detector head in the multi-component thermopile or pyroelectric infrared detector and the corresponding measured gas concentration;

[0047] S4, detecting the measurement channel and reference channel signals by a microfluidic infrared detector, and calculating the output signal intensity ratio of the measurement channel and the reference channel;

[0048] S5. Fitting the relationship between the signal intensity ratio of the measurement channel and the reference channel and the measured gas;

[0049] S6. A multi-component gas is introduced, and the concentrations of the various components in the multi-component gas are calculated based on the relationships determined in steps S3 and S5.

[0050] The beneficial effects brought about by the technical solution provided by the embodiments of the present invention are:

[0051] 1) No additional gas chamber is required. The multi-component thermopile or pyroelectric infrared detector can share a gas chamber with the microflow infrared detector at the tail to achieve simultaneous measurement of the concentration of multiple components of gases, thereby improving the response speed of gas measurement and effectively reducing the volume and cost of the measuring device; and by combining the microflow infrared detector with the multi-component thermopile or pyroelectric infrared detector, the technical problem of using thermopile detectors for exhaust gas monitoring, that is, the weak infrared absorption effect of thermopile infrared detectors, which cannot meet the requirements of multi-component wide-range measurement, is overcome; at the same time, the technical problem of high cost and large size of exhaust gas analyzers caused by the use of multiple independent pneumatic gas detectors is overcome, and while reducing the cost and volume of the gas analyzer, high-precision measurement of low-concentration gases is taken into account.

[0052] 2) The reflected signal is enhanced by providing a reflection device so that the multi-component thermopile or pyroelectric infrared detector and the microfluidic infrared detector can detect the signal simultaneously, and the signal-to-noise ratio is high;

[0053] 3) By setting up a reference channel to eliminate the error in the measurement results caused by long-term drift of infrared light, the measurement accuracy and stability of the analyzer can be improved; by using a microflow infrared detector, the concentration of low-range gases can be measured and the interference of moisture can be eliminated. Furthermore, by setting a light shield and adjustment plate on the multi-component thermopile or pyroelectric infrared detector, the accuracy of gas concentration measurement can be further improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 1 is a schematic structural diagram of a multi-component wide-range gas analyzer shown in the first embodiment of the present invention;

[0055] Figure 2 yes Figure 1 A schematic structural diagram of the detection cavity 3 is shown in FIG;

[0056] Figure 3 yes Figure 1 A schematic diagram of the local structure of a multi-component thermopile infrared detector is shown in FIG.

[0057] Figure 4 1 is a schematic diagram of a partial structure of a multi-component wide-range gas analyzer shown in the first embodiment of the present invention;

[0058] Figure 5 is a partial cross-sectional view of a multi-component wide-range gas analyzer shown in a second embodiment of the present invention;

[0059] Figure 6 is a partial cross-sectional view of a multi-component wide-range gas analyzer shown in a third embodiment of the present invention;

[0060] Figure 7 It is a partial cross-sectional view of a multi-component wide-range gas analyzer shown in the fourth embodiment of the present invention.

[0061] In the figure: 1-air chamber cavity, 11-partition, 12-measurement channel, 13-reference channel, 2-light source module, 21-light cutter, 3-detection cavity, 31-cross plate, 32-first channel, 33-second channel, 35-optical lens, 36-annular groove, 37-light blocking sleeve, 38-light hole, 4-reflection device, 5-multi-component thermopile or pyroelectric infrared detector, 6-microflow infrared detector, 7-adjustment plate, 71-adjustment hole. DETAILED DESCRIPTION

[0062] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0063] Example 1

[0064] Please refer to Figure 1 and Figure 2 An embodiment of the present invention provides a multi-component wide-range gas analyzer, comprising a gas chamber 1, a light source module 2, a detection chamber 3, a reflector 4, a multi-component thermopile or pyroelectric infrared detector 5, and a micro-flow infrared detector 6. The multi-component thermopile or pyroelectric infrared detector 5 is a multi-component thermopile infrared gas detector or a multi-component pyroelectric infrared gas detector.

[0065] A partition 11 is disposed along the central axis of the air chamber cavity 1, dividing the air chamber cavity 1 into a measurement channel 12 and a reference channel 13 of identical or similar size and shape. The partition 11 is the same length as the air chamber cavity 1 and is integrally formed with the air chamber cavity 1 to improve the airtightness of the measurement channel 12 and the reference channel 13, as well as the consistency of the two channels. In other embodiments, the partition 11 and the air chamber cavity 1 may also be connected by welding. In this embodiment, the measurement channel 12 and the reference channel 13 are symmetrically disposed relative to the partition 11. Preferably, the cross-sections of the measurement channel 12 and the reference channel 13 are both semicircular. In fact, this is not limited to this, and the cross-sections may also be rectangular or other geometric shapes.

[0066] In the present invention, a reference gas, such as N2, which does not absorb the light emitted by the light source module 2 is filled into the reference channel 13 of the gas chamber cavity 1. An air inlet and an air outlet are provided on the measurement channel 12 to allow the measured gas to flow into and out of the measurement channel 12.

[0067] The light source module 2 is arranged upstream of the air chamber cavity 1, and is used to emit illumination light containing the absorption band of the gas being measured. The light source module 2 includes a light source, a motor, and a light cutter 21. The light source and the motor are connected to the light cutter 21 via a mounting base, and the light cutter 21 is connected to the front end of the air chamber cavity 1 via the mounting base. A first light-transmitting hole and a second light-transmitting hole are provided on the light cutter 21. Driven by the motor, the light cutter 21 rotates at a constant speed, and the light emitted by the light source is periodically and alternately irradiated into the measurement channel 12 through the first light-transmitting hole, and into the reference channel 13 through the second light-transmitting hole. In this embodiment, the air chamber cavity 1 and the mounting base are connected by a flange structure. In order to prevent light drift caused by radial movement of the light source, a number of screws and screw holes are provided between the mounting base and the air chamber cavity 1, and a tight fit is achieved through the screws and screw holes.

[0068] Please refer to Figure 2 and Figure 3A detection cavity 3 is also provided between the air chamber cavity 1 and the micro-flow infrared detector 6. The detection cavity 3 is connected to the air chamber cavity 1 and the micro-flow infrared detector 6 through a mounting seat. The front end of the detection cavity 3 and the end of the air chamber cavity 1 are isolated from the air flow by an optical lens 35. At the same time, the light inside the air chamber cavity 1 can reach the detection cavity 3 through the optical lens 35. A pair of parallel grooves are symmetrically provided inside the detection cavity 3 along the extension line direction of the horizontal plate 31. The horizontal plate 31 is embedded in the parallel grooves to be fixed to the detection cavity 3. The horizontal plate 31 divides the detection cavity 3 into a first channel 32 and a second channel 33. The first channel 32 is connected to the air chamber cavity 1 is relatively matched in position, the second channel 33 is relatively matched in position with the reference channel 13 in the air chamber cavity 1, the cross plate 31 is the same length as the detection cavity 3, and the cross plate 31 is connected to the detection cavity 3 by gluing to prevent light leakage. In this embodiment, the first channel 32 and the second channel 33 are symmetrically arranged relative to the cross plate 31, and the first channel 32 and the second channel 33 have the same cross-sectional shape as the measuring channel 12 and the reference channel 13, so that the light emitted by the light source passes through the measuring channel 12 to irradiate the first channel 32, and the light emitted by the light source can pass through the reference channel 13 to irradiate the second channel 33.

[0069] In order to radially fix the air chamber cavity 1 and the detection cavity 3, a circular annular groove 36 is set at the front end of the detection cavity 3. The inner diameter of the annular groove 36 is larger than the outer diameter of the air chamber cavity 1, so that the right end part of the air chamber cavity 1 is embedded in the annular groove 36.

[0070] In the present invention, the multi-component gas measured in the measurement channel 12 and the first channel 32 absorbs infrared light of different wavelengths emitted by the light source, and the reference gas N2 in the reference channel 13 and the second channel 33 does not absorb the infrared light emitted by the light source.

[0071] The reflecting device 4 is arranged in the first channel 32 of the detection cavity 3. Specifically, the reflecting device 4 is arranged on the horizontal plate 31, and its reflecting surface is arranged between the light source module 2 and the multi-component thermopile or pyroelectric infrared detector 5. After the light emitted by the light source module 2 is absorbed by the measured gas in the measurement channel 12, part of it directly reaches the microflow infrared detector 6, and part of it reaches the multi-component thermopile or pyroelectric infrared detector 5 through the reflecting device 4, so that the multi-component thermopile or pyroelectric infrared detector 5 and the microflow infrared detector 6 can detect the light signal at the same time, thereby realizing the simultaneous measurement of different gas components in the multi-component gas. There is a certain angle between the reflecting device 4 and the horizontal plate 31. In order to make the light signal received by the multi-component thermopile or pyroelectric infrared detector 5 more uniform, preferably, the angle between the reflecting device 4 and the horizontal plate 31 is 45°, and the center of the multi-component thermopile or pyroelectric infrared detector 5 is on the same straight line as the center of the reflecting device 4. In this embodiment, in order to enhance the reflection effect of the reflecting device 4, a coating can be provided on the reflecting surface. Further, in order to enhance the reflection effect and enable the detector to detect sufficient light signals, a coating is applied on the inner wall of the air chamber cavity 1 and the detection cavity 3 and the horizontal plate 31. The coating has little absorption of light in the detection band of the detector.

[0072] The multi-component thermopile or pyroelectric infrared detector 5 is disposed on the side wall of the detection cavity 3 and is arranged opposite the reflector 4. The multi-component thermopile or pyroelectric infrared detector 5 is used to receive and detect the intensity of light emitted by the light source module 2 and reflected by the reflector 4. Specifically, the multi-component thermopile or pyroelectric infrared detector 5 is mounted on the inner side wall of the first channel 32, and the center of the reflector 4 and the center of the multi-component thermopile or pyroelectric infrared detector 5 are located on the same vertical line. In this embodiment, the multi-component thermopile or pyroelectric infrared detector 5 is a composite infrared detector that can simultaneously measure the concentration of multiple gas components. When measuring exhaust gas, it can simultaneously measure the gas concentrations of CO, CO2, and HC. When the multi-component thermopile or pyroelectric infrared detector 5 can simultaneously measure CO, CO2, and HC, it can determine the light intensity attenuation in the corresponding absorption bands based on the absorption characteristics of CO, CO2, and HC, respectively, and convert the detection results into electrical signals.

[0073] The multi-component thermopile or pyroelectric infrared detector 5 includes a reference probe Ref and multiple measurement probes. The reference probe Ref and the multiple measurement probes are in the same plane. Figure 1In this embodiment, the multi-component thermopile or pyroelectric infrared detector 5 includes four detection heads, a reference detection head Ref and three measurement detection heads. When the gas analyzer disclosed in this patent is used to measure exhaust gas, the three measurement detection heads of the multi-component thermopile or pyroelectric infrared detector 5 are used to measure the concentrations of CO, CO2 and HC in the exhaust gas, respectively, and the microflow infrared detector 6 is used to measure the concentration of low-concentration NO.

[0074] In fact, there is no limitation on the number of detection heads of the multi-component thermopile or pyroelectric infrared detector 5 , nor on the concentration of the gas measured by each detection head.

[0075] Please refer to Figure 3 In order to allow the optical signal to enter the multi-component thermopile or pyroelectric infrared detector 5 at an optimal incident angle, a light-blocking sleeve 37 is provided on the lower end of the multi-component thermopile or pyroelectric infrared detector 5 in the present invention, and a light-through hole 38 is opened on the light-blocking sleeve 37. The size of the light-through hole 38 is adapted to the detection surface of the multi-component thermopile or pyroelectric infrared detector 5, and the center of the detection surface of the multi-component thermopile or pyroelectric infrared detector 5 coincides with the center of the light-through hole 38. When the detection surface diameter D and the optimal sensing angle α of the multi-component thermopile or pyroelectric infrared detector 5 are constant, the angle α of the light entering the multi-component thermopile or pyroelectric infrared detector 5 can be controlled by adjusting the thickness H of the light-blocking sleeve 37, so that the light reflected by the reflecting device 4 can enter the multi-component thermopile or pyroelectric infrared detector 5 at the optimal angle, thereby reducing the interference of light entering at other angles on the multi-component thermopile or pyroelectric infrared detector 5.

[0076] For example, when the diameter of the detection surface of the multi-component thermopile or pyroelectric infrared detector 5 is D=4.5mm and the optimal sensing angle α of the multi-component thermopile or pyroelectric infrared detector 5 is 120°, in order to ensure that the light signal detected by the multi-component thermopile or pyroelectric infrared detector 5 is stable and free from stray light interference, the incident angle of the light entering the multi-component thermopile or pyroelectric infrared detector 5 can be controlled to be α. The thickness of the light-blocking sleeve 37 can be calculated according to the calculation formula of the side length of the right triangle. The optimal sensing angle α and detection surface diameter D of the multi-component thermopile or pyroelectric infrared detector 5 can be obtained by querying the parameters in the data manual; in addition, when the light-blocking sleeve 37 is actually selected, the thickness H of the light-blocking sleeve 37 can be adjusted within the range of ±5% of the calculated result, that is, in fact, the thickness of the light-blocking sleeve 37 can meet the requirements within the range of 95%H to 105%H.

[0077] In the present invention, the microflow infrared detector 6 is installed at the end of the detection cavity 3 through a mounting base. The microflow infrared detector 6 is used to receive and detect the light intensity in the first channel 32 and the second channel 33 in a time-sharing manner. In this embodiment, a filter is provided between the detection cavity 3 and the microflow infrared detector 6. The filter can eliminate or reduce the influence of scattered and interfering components and allow infrared light with a characteristic absorption wavelength to pass through.

[0078] The microstream infrared detector 6 of the present invention can be a detector for measuring the composition and concentration of a specific gas, such as an NO microstream infrared detector, a SO2 detector, or other detectors. When the microstream infrared detector 6 is an NO detector, it can measure the light intensity attenuation within the corresponding absorption band based on the NO absorption characteristics of infrared light and convert the detection result into an electrical signal.

[0079] The specific measuring method of the present invention is:

[0080] S1. Fill the measurement channel 12 with a gas of known concentration to be measured, and fill the reference channel 13 with a reference gas. The infrared light emitted by the light source module 2 is emitted into the measurement channel 12 and the reference channel 13 in a time-sharing manner. The gas to be measured in the measurement channel 12 absorbs infrared light of a specific wavelength, while the reference gas in the reference channel 13 does not absorb infrared light.

[0081] S2. The multi-component thermopile or pyroelectric infrared detector 5 includes a reference detection head Ref and multiple measurement detection heads. The detection heads of the multi-component thermopile or pyroelectric infrared detector 5 synchronously detect the optical signal of the measurement channel 12, and calculate the ratio of the output signal intensity of each measurement detection head to the reference detection head. Specifically, the infrared light emitted from the measurement channel 12 and the reference channel 13 enters the first channel 32 and the second channel 33, wherein a portion of the infrared light entering the first channel 32 is reflected by the reflection device 4 to the multi-component thermopile or pyroelectric infrared detector 5. In this embodiment, the multi-component thermopile or pyroelectric infrared detector 5 includes four detection heads, one of which is a reference detection head and the other three are measurement detection heads. In fact, there is no limit on the number of detection heads of the multi-component thermopile or pyroelectric infrared detector 5.

[0082] S3, respectively fitting the relationship between the output signal intensity ratio of each measuring detector head and the reference detector head in the multi-component thermopile or pyroelectric infrared detector 5 and the corresponding measured gas concentration;

[0083] S4, using the microfluidic infrared detector 6 to detect the optical signals of the measurement channel 12 and the reference channel 13 in a time-sharing manner, and output corresponding electrical signals, and calculate the output signal intensity ratio of the measurement channel 12 and the reference channel 13;

[0084] S5, fitting the relationship between the signal intensity ratio of the measurement channel 12 and the reference channel 13 and the concentration of the measured gas;

[0085] S6. A multi-component gas to be measured is introduced, and the concentrations of the various components in the multi-component gas are calculated based on the ratios of the output signals of the measurement probes of the multi-component thermopile or pyroelectric infrared detector 5 to the output signals of the reference probe, and the ratio of the signal intensities output by the measurement channel 12 and the reference channel 13, combined with the relationship determined in steps S3 and S5.

[0086] Compared with multiple micro-flow infrared detectors 6, the cost of the multi-component thermopile or pyroelectric infrared detector 5 is relatively low, but the micro-flow infrared detector 6 can measure low concentrations of the measured gas. Therefore, by combining the micro-flow infrared detector with the multi-component thermopile or pyroelectric infrared detector 5, while realizing the simultaneous measurement of the concentration of multiple components of gas, the cost of the gas analyzer and the measurement of low concentration gas concentration are taken into account.

[0087] Since the light intensity detected from the reference channel 13 corresponds to the initial light intensity of the light source, and the light intensity detected from the measurement channel 12 corresponds to the light intensity after being absorbed by the measured gas, the concentration of the measured gas can be obtained based on the relationship between the ratio of the light intensity data of the two channels and the concentration of the measured gas. Figure 1 and Figure 4 In the process of measuring the composition of multi-component gases, since a reflecting device 4 is provided on the horizontal plate 31 in the first channel 32, the setting of the reflecting device 4 will partially block the light received by the microflow infrared detector 6, which will result in different light intensities received by the microflow infrared detector 6 from the two channels even if the same concentration of gas is introduced into the measuring channel 12 and the reference channel 13. At the same time, since there may be consistency differences between the measuring channel 12 and the reference channel 13 during the processing process, the consistency differences between the two channels will also result in different light intensities received by the microflow infrared detector 6 from the two channels even if the same concentration of gas is introduced into the measuring channel 12 and the reference channel 13. The structural differences between the two channels and the setting of the reflecting device 4 result in differences in the initial light intensities received by the microflow infrared detector 6 from the two channels, and this initial light intensity difference will cause errors in the measurement results.

[0088] Please refer to Figure 4To eliminate measurement errors caused by the structural differences between the two channels and the placement of the reflector 4, the present invention provides an adjustment plate 7 between the detection cavity 3 and the microflow infrared detector 6. An adjustment hole 71 is provided in the center of the adjustment plate 7 for adjusting the optical signals received by the microflow infrared detector 6 from the two channels. The specific adjustment method is as follows: a gas with exactly the same composition and concentration, such as pure N2, is introduced into the measurement channel 12 and the reference channel 13. By moving the adjustment plate 7 up and down, the light intensities received by the microflow infrared detector 6 from the measurement channel 12 and the reference channel 13 are equalized. At this point, fixing the position of the adjustment plate 7 eliminates measurement errors caused by the structural differences between the two channels and the placement of the reflector 4. When it is found that the light intensity detected from the measurement channel 12 is less than the light intensity detected from the reference channel 13, the adjustment plate 7 can be moved upward to allow more light to pass through the adjustment hole 71 from the measurement channel 12 to reach the microflow infrared detector 6. The adjustment plate 7 blocks the light passing through the reference channel 13 more, so that less light can pass through the adjustment hole 71 from the reference channel 13 to reach the microflow infrared detector 6. In this way, it can be ensured that when the composition and concentration of the gas introduced into the measurement channel 12 and the reference channel 13 are the same, the light intensity received by the microflow infrared detector 6 from the measurement channel 12 and the reference channel 13 is equal.

[0089] Example 2

[0090] Please refer to Figure 5 The difference between this embodiment and the first embodiment is that the gas chamber cavity 1 is a single gas chamber cavity rather than a half-gas chamber, and the gas chamber cavity 1 is only filled with the gas to be measured, but not with the reference gas.

[0091] That is, no partition 11 is provided in the air chamber cavity 1 , and correspondingly no transverse plate 31 is provided in the detection cavity 3 . Both the air chamber cavity 1 and the detection cavity 3 are single-channel cavities.

[0092] In this embodiment, in order to improve the signal-to-noise ratio of the detection signal of the multi-component thermopile or pyroelectric infrared detector 5, a reflection device 4 is set in the detection cavity 3. However, since diffuse reflection exists in both the gas chamber cavity 1 and the detection cavity 3, when the reflection device 4 in Example 1 is omitted, the infrared light emitted by the light source module 2 can also reach the multi-component thermopile or pyroelectric infrared detector 5 and the microflow infrared detector 6 through diffuse reflection, thereby measuring the concentrations of multiple gas components in the measured gas.

[0093] When measuring the concentration of the gas being measured, the multi-component thermopile or pyroelectric infrared detector 5 and the microflow infrared detector 6 receive and analyze the infrared light emitted by the light source module 2, and the signal processing system processes and calculates the signals output by the multi-component thermopile or pyroelectric infrared detector 5 and the microflow infrared detector 6 according to the conversion formula of the gas concentration and outputs the concentration value of the measured gas.

[0094] Example 3

[0095] Please refer to Figure 6 The difference between this embodiment and the first embodiment is that the position of the multi-component thermopile or pyroelectric infrared detector 5 is different. The multi-component thermopile or pyroelectric infrared detector 5 is arranged on the side wall of the measuring channel 12 in the gas chamber cavity 1, rather than on the side wall of the detection cavity 3. In this case, the detection cavity 3 is omitted, and the microflow infrared detector 6 is connected to the rear end of the gas chamber cavity 1.

[0096] exist Figure 6 While the reflector 4 is not shown, the infrared light emitted by the light source module 2 can also reach the multi-component thermopile or pyroelectric infrared detector 5 and the microflow infrared detector 6 through diffuse reflection, thereby measuring the concentrations of multiple gas components in the measured gas. Of course, to improve the signal-to-noise ratio of the detection signal from the multi-component thermopile or pyroelectric infrared detector 5, the reflector 4 can also be installed in the measurement channel 12. Preferably, the reflector 4 is installed on the partition 11 in the measurement channel 12.

[0097] In order to improve the accuracy of the measurement data of the multi-component thermopile or pyroelectric infrared detector 5, the multi-component thermopile or pyroelectric infrared detector 5 is set at the end of the gas chamber cavity 1, close to the microflow infrared detector 6 so that the light signal detected by the multi-component thermopile or pyroelectric infrared detector 5 is the light intensity after being fully absorbed by the gas being measured.

[0098] Example 4

[0099] Please refer to Figure 7 The difference between this embodiment and the third embodiment is that the gas chamber cavity 1 is a single gas chamber cavity rather than a half-gas chamber, and the gas chamber cavity 1 is only filled with the gas to be measured, but not with the reference gas.

[0100] In this document, directional terms such as front, back, top, and bottom are defined based on the positions of components in the accompanying drawings and relative to each other, and are intended only for clarity and convenience in describing the technical solution. It should be understood that the use of directional terms should not limit the scope of protection claimed in this application.

[0101] In the absence of conflict, the above embodiments and features in the embodiments may be combined with each other.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A multi-component wide-range gas analyzer, characterized in that ,include: The gas chamber cavity comprises at least one measuring channel, and the measuring channel is used to be filled with the gas to be measured; A light source module is provided upstream of the gas chamber cavity and is used to emit illumination light containing an absorption band of the gas to be measured; Multi-component thermopile or pyroelectric infrared detector and micro-flow infrared detector, used to receive the irradiation light emitted by the light source module and absorbed by the gas to be measured; The micro-flow infrared detector is located downstream of the gas chamber cavity, and the multi-component thermopile or pyroelectric infrared detector is located on the side wall of the multi-component wide-range gas analyzer; Multi-component thermopile or pyroelectric infrared detectors are used to simultaneously measure multiple high-concentration component gases, and microflow infrared detectors are used to measure low-concentration gases.

2. The multi-component wide-range gas analyzer according to claim 1, wherein: The multi-component wide-range gas analyzer further includes a reflecting device for reflecting the irradiation light emitted by the light source module and absorbed by the measured gas so as to be received and detected by the multi-component thermopile or pyroelectric infrared detector.

3. The multi-component wide-range gas analyzer according to claim 2, wherein: The center of the reflecting device and the center of the multi-component thermopile or the pyroelectric infrared detector are located on the same vertical line, and a certain angle is formed between the reflecting device and the horizontal plate.

4. The multi-component wide-range gas analyzer according to claim 1, wherein: A light-blocking sleeve is provided on the multi-component thermopile or the pyroelectric infrared detector, and a light-through hole is provided on the light-blocking sleeve.

5. The multi-component wide-range gas analyzer according to claim 4, characterized in that: The size of the light hole is adapted to the detection surface of the multi-component thermopile or pyroelectric infrared detector, and the center of the detection surface of the multi-component thermopile or pyroelectric infrared detector coincides with the center of the light hole. Therefore, by adjusting the thickness of the light shielding sleeve, the angle of light entering the multi-component thermopile or pyroelectric infrared detector can be controlled, so that the light reflected by the reflecting device can enter the multi-component thermopile or pyroelectric infrared detector at the optimal angle, thereby reducing the interference of light entering at other angles on the multi-component thermopile or pyroelectric infrared detector.

6. The multi-component wide-range gas analyzer according to claim 5, characterized in that: By consulting the data sheet, the optimal sensing angle α and detection surface diameter D of the multi-component thermopile or pyroelectric infrared detector can be obtained. The thickness H of the light-blocking sleeve can be calculated according to the formula H=D / 2tanα / 2. The thickness of the light-blocking sleeve can meet the requirements within the range of 95%H~105%H.

7. The multi-component wide-range gas analyzer according to any one of claims 1 to 6, characterized in that: A partition is provided along the central axis of the air chamber cavity to divide the air chamber cavity into a measurement channel and a reference channel of the same size and shape.

8. The multi-component wide-range gas analyzer according to claim 7, wherein: An adjustment plate is movably connected between the air chamber cavity and the micro-flow infrared detector, and an adjustment hole for adjusting the optical signals received by the micro-flow infrared detector from the measurement channel and the reference channel is provided in the middle of the adjustment plate.

9. The multi-component wide-range gas analyzer according to claim 8, characterized in that: The adjustment board adjusts the optical signal through the following steps: S1: Introduce gases with identical composition and concentration into the measurement channel and the reference channel; S2: Use the microfluidic infrared detector to detect the light intensity received from the measurement channel and the reference channel respectively, and record them as M and R respectively, and determine whether M and R are equal; S3: When M≠R, the light intensity received by the microflow infrared detector from the measurement channel and the reference channel is equal by moving the adjustment plate up and down. At this time, fixing the position of the adjustment plate can eliminate the measurement error caused by the structural difference between the two channels and the setting of the reflection device. When M=R, there is no need to move the position of the adjustment plate.

10. The multi-component wide-range gas analyzer according to claim 9, characterized in that: The optical signal adjustment by the adjustment board also includes the following steps: When M<R, the adjustment plate can be moved upward to allow more light to pass through the adjustment hole from the measurement channel to reach the microflow infrared detector. The adjustment plate blocks more light passing through the reference channel, allowing less light to pass through the adjustment hole from the reference channel to reach the microflow infrared detector, until M=R. When M>R, the adjustment plate can be moved downward to allow more light to pass through the adjustment hole from the reference channel to reach the microflow infrared detector. The adjustment plate blocks more light passing through the measurement channel, allowing less light to pass through the adjustment hole from the measurement channel to reach the microflow infrared detector, until M=R.

11. The multi-component wide-range gas analyzer according to claim 7, wherein: The multi-component wide-range gas analyzer also includes a detection cavity, the front end of which is connected to the end of the gas chamber cavity, and a transverse plate is provided along the extension line of the partition plate, the transverse plate divides the detection cavity into a first channel and a second channel, the first channel is arranged opposite to the measurement channel, and the second channel is arranged opposite to the reference channel; The reflection device is arranged in the first channel of the detection cavity; The multi-component thermopile or pyroelectric infrared detector is arranged in the first channel and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device; The micro-flow infrared detector is arranged at the end of the detection cavity, and is used for receiving and detecting the light intensity in the first channel and the second channel respectively.

12. The multi-component wide-range gas analyzer according to claim 7, wherein: The reflecting device is arranged in the measuring channel of the air chamber cavity and is located on the partition; The multi-component thermopile or pyroelectric infrared detector is arranged in the measuring channel and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device.

13. The multi-component wide-range gas analyzer according to any one of claims 2 to 6, characterized in that: The multi-component wide-range gas analyzer further includes a detection cavity, the front end of which is connected to the end of the gas chamber cavity; The reflection device is arranged in the detection cavity; The multi-component thermopile or pyroelectric infrared detector is arranged inside the detection cavity and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device; The micro-flow infrared detector is arranged at the end of the detection cavity and is used to receive and detect the light intensity in the first channel and the second channel respectively.

14. The multi-component wide-range gas analyzer according to any one of claims 2 to 6, characterized in that: a reflector disposed in the measuring channel of the air chamber cavity and located on the partition; The multi-component thermopile or pyroelectric infrared detector is arranged in the measuring channel and opposite to the reflecting device, and is used to receive and detect the intensity of light reflected by the reflecting device.

15. A gas analysis method, applied to the multi-component wide-range gas analyzer according to claim 11, characterized in that: The gas analysis method includes the following steps: S1. Fill the measurement channel with a gas of known concentration to be measured, and fill the reference channel with a reference gas. The infrared light emitted by the light source module is emitted into the measurement channel and the reference channel in a time-sharing manner. S2. The multi-component thermopile or pyroelectric infrared detector includes a reference probe and multiple measurement probes. Each probe of the multi-component thermopile or pyroelectric infrared detector synchronously detects the optical signal of the measurement channel and calculates the ratio of the output signal intensity of each measurement probe to that of the reference probe. S3, respectively fitting the relationship between the output signal intensity ratio of each measuring detector head and the reference detector head in the multi-component thermopile or pyroelectric infrared detector and the corresponding measured gas concentration; S4. Detecting the optical signals of the measurement channel and the reference channel by a microfluidic infrared detector, outputting corresponding electrical signals, and calculating the output signal intensity ratio of the measurement channel and the reference channel; S5. Fitting the relationship between the signal intensity ratio of the measurement channel and the reference channel output and the measured gas; S6. A multi-component gas to be measured is introduced, and the concentrations of the various components in the multi-component gas are calculated based on the ratios of the output signals of the measurement probes of the multi-component thermopile or pyroelectric infrared detector to the output signals of the reference probe, as well as the ratio of the signal intensities of the outputs of the measurement channel and the reference channel, combined with the relationships determined in steps S3 and S5.

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