Gas concentration analysis device based on high-temperature optical principle

Abstract

The invention discloses a gas concentration analysis device based on a high-temperature optical principle, which comprises a device body, the device body comprises a light source, an optical beam splitter, a measuring light pool, a high-temperature-resistant light guide column, a measuring end detector and a reference end detector; the high-temperature-resistant light guide column comprises a first light guide column and a second light guide column, and the first light guide column and the second light guide column are located on the two sides of the measuring light pool respectively; the light source is connected with the light source beam splitter and is divided into a first light beam and a second light beam through the light source beam splitter. According to the invention, the measurement light cell is isolated from an electronic device, and the light cell can be heated to a temperature higher than the dew point of the sample gas, so that the sample gas can be sent into the light cell for analysis without dehydration treatment on the sample gas; component loss in the dehydration process is avoided; the optical structure is simple, the performance is improved under the condition that the cost is almost not increased, more applicable working conditions are achieved, and the maintenance amount is small.

Description

Technical Field

[0001] The present invention relates to the technical field of gas concentration analysis, and particularly to a gas concentration analysis device based on a high-temperature optical principle. Background Art

[0002] Gas concentration analysis is an essential and important link in fields such as environmental monitoring, industrial production, and safety protection. A detailed introduction to gas concentration analysis methods is as follows: Gas Concentration Analysis Methods Gas colorimetry: By comparing the color depth of a gas sample with that of a standard gas sample to determine the content of a certain component in the gas, it is applicable to the analysis of gases with relatively low concentrations.

[0003] Gas sensor method: Utilizing the sensitivity of a gas sensor to specific gas molecules, converting the gas concentration into an electrical signal, it is applicable to portable and on-line monitoring gas analysis.

[0004] Gas chromatography: Using a gaseous carrier to separate sample components and combining with a detector to measure the concentration of each component, it is applicable to the separation and determination of multiple components in complex gas samples.

[0005] Mass spectrometry: Using a mass analyzer to separate sample ions and calculating the concentration of a certain component in the gas according to the intensity or area of the ion peak, it is applicable to trace and ultra-trace gas analysis.

[0006] Infrared spectroscopy analysis: By measuring the absorption of infrared light by gas molecules to determine the type and concentration of the gas, it features fast speed, non-destructiveness, and high sensitivity.

[0007] Electrochemical sensor analysis method: Detecting gas components and concentrations through an electrochemical reaction, it features small volume, high sensitivity, and fast response. Gas concentration analysis is an essential and important link in fields such as environmental monitoring, industrial production, and safety protection. The following is a detailed introduction to gas concentration analysis methods: Gas Concentration Analysis Methods Gas colorimetry: By comparing the color depth of a gas sample with that of a standard gas sample to determine the content of a certain component in the gas, it is applicable to the analysis of gases with relatively low concentrations.

[0008] Gas sensor method: Utilizing the sensitivity of a gas sensor to specific gas molecules, converting the gas concentration into an electrical signal, it is applicable to portable and on-line monitoring gas analysis.

[0009] Gas chromatography: Using a gaseous carrier to separate sample components and combining with a detector to measure the concentration of each component, it is applicable to the separation and determination of multiple components in complex gas samples.

[0010] Mass spectrometry: The sample ions are separated by a mass analyzer, and the concentration of a certain component in the gas is calculated according to the intensity or area of the ion peak. It is applicable to trace and ultra-trace gas analysis5.

[0011] Infrared spectroscopy analysis: By measuring the absorption of infrared light by gas molecules, the type and concentration of the gas are determined, which has the characteristics of fast speed, non-destructiveness and high sensitivity7.

[0012] At present, the heating temperature of the light cell gas chamber of conventional non-dispersive infrared or non-dispersive ultraviolet optical analyzers is generally relatively low, not exceeding 60 °C. Therefore, before the sample gas enters the light cell, the sample gas must be dehydrated. Otherwise, the sample gas may condense and dew in the light cell, contaminating the light cell and optical lenses. Simply increasing the heating temperature of the light cell will cause the temperature of the electronic devices at both ends of the light cell to be too high, resulting in changes in the electrical characteristics of the instrument and even damage to the devices.

[0013] As described above, for this reason, we have designed a gas concentration analysis device based on the high-temperature optical principle to solve the above problems. Summary of the Invention

[0014] The purpose of the present invention is to solve the disadvantages existing in the prior art, and to propose a gas concentration analysis device based on the high-temperature optical principle.

[0015] In order to achieve the above purpose, the present invention adopts the following technical solutions: A gas concentration analysis device based on the high-temperature optical principle, including a device body, and the device body includes: a light source, an optical beam splitter, a measurement light cell, a high-temperature resistant light guide column, a measurement end detector, and a reference end detector; The high-temperature resistant light guide column includes a first light guide column and a second light guide column, and the first light guide column and the second light guide column are respectively located on both sides of the measurement light cell; The light source is connected to a light source beam splitter, and is divided into a first beam of light and a second beam of light through the light source beam splitter. The terminal of the first beam of light sequentially passes through the first light guide column, the measurement light cell and the second light guide column, and is connected to the measurement end detector; the terminal of the second beam of light is connected to the reference end detector; The first light guide column and the second light guide column are made of light-transmitting clean quartz glass material; The measurement light cell is a small gas chamber for storing the gas to be measured, and is provided with an air inlet and an air outlet, and both ends of the measurement light cell are sealed with optical glass.

[0016] Preferably, the device body further includes a pressure sensor, a temperature and humidity sensor, and a signal control circuit board, and the pressure sensor and the temperature and humidity sensor are connected to the signal control circuit board through line signals; The light source, optical beam splitter, measuring end detector, and reference end detector are all connected to the signal control circuit board through wired signals.

[0017] Preferably, the signal control circuit board is used to control the electrical signals of the device body, including: one or more of high-frequency modulation of the light source, constant temperature control of the system, acquisition and processing of signals from the measuring end detector, acquisition and processing of signals from the reference end detector, acquisition and processing of signals from the pressure sensor, acquisition and processing of signals from the temperature and humidity sensor, operation of the light intensity and concentration model algorithm, and calibration operation of the system.

[0018] Preferably, a narrowband filter is placed between the second light guide column and the measuring end detector.

[0019] Preferably, a constant temperature purge fan for cooling the first light guide column and the second light guide column is also placed outside the first light guide column and the second light guide column.

[0020] Preferably, the measuring end detector is used to measure the intensity of the first light beam that passes through the measuring light cell after the light beam emitted by the light source forms the first light beam through the optical beam splitter; the reference end detector is used to measure the intensity of the second light beam of the second light beam formed by the light beam emitted by the light source passing through the optical beam splitter.

[0021] Preferably, a narrowband filter corresponding to the measuring light cell is placed between the second light guide column and the measuring end detector.

[0022] Preferably, the operation of the concentration model algorithm includes: establishing a model for the gas concentration by calculating the change in light intensity of the first light beam at different gas concentrations through the Lambert-Beer law, and obtaining the gas concentration entering the measuring gas chamber based on the light intensity.

[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention isolates the measuring light cell from the electronic devices, and the light cell can be heated to a temperature higher than the dew point of the sample gas, so that the sample gas can be sent into the light cell for analysis without dehydrating the sample gas; avoiding component loss during the dehydration process.

[0024] 2. The optical structure of the present invention is simple, the performance is improved with almost no increase in cost, it is applicable to more working conditions, and the maintenance amount is small. Description of the Drawings

[0025] Figure 1 It is a schematic structural diagram of a gas concentration analysis device based on a high-temperature optical principle proposed by the present invention; Figure 2 It is a working flow chart of a gas concentration analysis device based on a high-temperature optical principle proposed by the present invention.

[0026] In the figure: 1 light source, 101 first light beam, 102 second light beam, 2 optical beam splitter, 3 measurement light cell, 4 high-temperature resistant light guide column, 401 first light guide column, 402 second light guide column, 5 measurement end detector, 6 reference end detector, 7 pressure sensor and temperature and humidity sensor, 8 signal control circuit board. Detailed implementation mode

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0028] Refer to Figure 1 , a gas concentration analysis device based on a high-temperature optical principle, including a device body, and the device body includes: a light source 1, an optical beam splitter 2, a measurement light cell 3, a high-temperature resistant light guide column 4, a measurement end detector 5, and a reference end detector 6; In this embodiment, the high-temperature resistant light guide column 4 includes a first light guide column 401 and a second light guide column 402, and the first light guide column 401 and the second light guide column 402 are respectively located on both sides of the measurement light cell 3; by adding the first light guide column 401 and the second light guide column 402 on both sides of the measurement light cell 3, the entire measurement light cell can be placed in a high-temperature area greater than 80 °C, which can effectively avoid the condensation of water vapor in the sample gas to be measured.

[0029] The light source 1 is connected to the light source beam splitter 2, and is divided into a first light beam 101 and a second light beam 102 through the light source beam splitter 2. The terminal of the first light beam 101 sequentially passes through the first light guide column 401, the measurement light cell 3 and the second light guide column 402, and is connected to the measurement end detector 5; the terminal of the second light beam 102 is connected to the reference end detector 6.

[0030] Configure the optical beam splitter 2 to perform semi-transmissive and semi-reflective light splitting on the light of the light source 1. The second light beam separated has relatively stable conditions and can be used to normalize the intensity of the first light beam, which can effectively avoid the influence of light source attenuation on the measured value.

[0031] Among them, the purpose of normalization is actually to facilitate data processing, that is, using the second light intensity data as a reference point or dividing the difference between the first light intensity and the second light intensity by the second light intensity.

[0032] The first light guide column 401 and the second light guide column 402 are made of light-transmitting and clean quartz glass; the measurement light cell 3 is a small gas chamber for storing the gas to be measured, and is equipped with an air inlet 10 and an air outlet 11. Both ends of the measurement light cell 3 are sealed with optical glass, and a narrow-band filter is placed between the second light guide column 402 and the measurement end detector 5. The narrow-band filter corresponding to the component to be measured is placed between the second light guide column 402 and the measurement end detector 5 to filter out the light of the absorption frequency of the non-component to be measured. The measurement end detector 5 can detect the change in the light intensity of the light related to the concentration of the component to be measured; Due to the existence of the high-temperature light guide column, the entire measurement light cell 3 can be placed in a high-temperature area greater than 80 °C, which can effectively avoid the condensation of water vapor in the gas sample to be measured.

[0033] In the above embodiment, the measurement end detector 5 is used to measure the intensity of the first light beam after the first light beam formed by the light beam emitted by the light source 1 passing through the optical beam splitter 2 and passing through the measurement light cell 3; the reference end detector 6 is used to measure the second light intensity of the second light beam formed by the light beam emitted by the light source 1 passing through the optical beam splitter.

[0034] Among them, the device body further includes a pressure sensor, a temperature and humidity sensor 7, and a signal control circuit board 8. The pressure sensor and the temperature and humidity sensor 7 are connected to the signal control circuit board 8 through line signals; the light source 1, the optical beam splitter 2, the measurement end detector 5, and the reference end detector 6 are all connected to the signal control circuit board 8 through wired signals.

[0035] More specifically, the measurement light cell 3 is a small gas chamber for storing the gas to be measured, equipped with air inlet and outlet, and both ends are sealed with optical glass to facilitate the passage of light through the measurement light cell 3; the high-temperature-resistant light guide column, usually made of light-transmitting and clean quartz glass, is used to connect the light source 1 and the measurement light cell 3, and the measurement light cell 3 and the measurement end detector 5; the pressure sensor is used to measure the gas pressure inside the light cell, and the pressure signal is used to compensate the light intensity and gas concentration model under different pressures or flows; the temperature and humidity sensor is used to measure the gas temperature and humidity inside the light cell, and the temperature and humidity signal is used to compensate the light intensity and gas concentration model under different temperature and humidity conditions; The signal control circuit board 8 is used to control the electrical signals of the device body, including: high-frequency modulation of the light source, system constant temperature control, acquisition and processing of the measurement end detector signal, acquisition and processing of the reference end detector signal, acquisition and processing of the pressure sensor signal, acquisition and processing of the temperature and humidity sensor signal, operation of the light intensity and concentration model algorithm, and one or more of the calibration operations of the system.

[0036] Wherein, a constant-temperature purging fan for cooling the first light guide column 401 and the second light guide column 402 is also placed outside the first light guide column 401 and the second light guide column 402, so that high temperature will not be conducted along the light guide column towards the light source 1 and the measuring end detector 5, reducing the aging of electronic components at high temperature.

[0037] In this embodiment, a narrowband filter corresponding to the measurement optical cell 3 is placed between the second light guide column 402 and the measuring end detector 5 to filter out the light with the absorption frequency of non-analyte components, and the measuring end detector can detect the change in the light intensity of the light related to the concentration of the analyte.

[0038] Among them, the operation of the concentration model algorithm includes: establishing a model for the gas concentration by calculating the change in the light intensity of the first light beam at different gas concentrations through the Lambert-Beer law, and obtaining the gas concentration entering the measurement gas chamber based on the light intensity.

[0039] More specifically, after the overall hardware architecture is built, the model establishment is a data fitting process. A set of standard gases (covering the test range of the instrument, not less than 10 points, such as when the range is 0-100 ppm, 11 points are selected, which can be evenly distributed or distributed according to needs, and different standard gas points 0, 10, 20,..., 90, 100 are selected) are introduced into the optical cell. When the output of the measuring end detector is stable, the light intensity values corresponding to the standard gas concentration are read and recorded, and 11 light intensity values will be obtained. A high-order polynomial is fitted according to the data of the light intensity and the standard gas concentration.

[0040] It should be noted that as Figure 2 shown, in this embodiment, the specific working steps are as follows: Step S1, the light source emits a light beam: The light source in the device emits a light beam.

[0041] Step S2, the optical beam splitter 2 splits the light: The light beam is split into two beams by the optical beam splitter 2: the first light beam enters the measurement optical cell 3, and the second light beam directly enters the reference end detector 6.

[0042] Step S3, the light beam passes through the analyte gas: The first light beam passes through the analyte gas in the measurement optical cell 3, and the gas molecules will absorb the light of a specific wavelength, resulting in a decrease in the light intensity.

[0043] Function of the high-temperature resistant light guide column 4: The light guide column ensures that the light beam can be stably transmitted from the light source 1 to the measurement optical cell 3 and from the measurement optical cell 3 to the measuring end detector 5, and its high-temperature resistant characteristic ensures normal operation in a high-temperature environment.

[0044] Step S4, the detector measures the light intensity: including the measuring end detector 5: measuring the intensity of the first light beam after gas absorption, and the recorded data reflects the attenuation of light under a specific gas concentration. The reference end detector measures the intensity of the second light beam without gas absorption. A reference value is provided to correct the influence of system errors and environmental factors.

[0045] Step S5, environmental parameter monitoring and compensation: including a pressure sensor and a temperature and humidity sensor 7: real-time monitoring of the gas pressure, temperature and humidity inside the optical cell. These parameters will affect the light propagation efficiency and absorption characteristics. The collected signals are used for real-time compensation of the measurement results to improve accuracy.

[0046] More specifically, by adding a pressure measurement sensor inside the optical cell, the pressure change of the optical cell can be measured, and pressure correction compensation can be performed on the light intensity-concentration model to solve the influence of different sample gas flow rates on the final concentration value in practical applications. Compensate for the influence of temperature and pressure changes on the measurement value. The changes in pressure and temperature will affect the light intensity detection value of the measuring end detector. Therefore, measure the light intensity changes of the same concentration gas under different temperatures and pressures, add correction factors, and perform model correction on the light intensity and concentration polynomials.

[0047] The standard condition of China's environmental protection standard is 101325 Pa and 0 °C. However, the temperature and pressure conditions inside the optical cell cannot reach this condition. By adding temperature and pressure sensors, measure the actual temperature and pressure, and perform standard condition conversion and correction according to the thermodynamic equation to output the standard condition value.

[0048] By adding a temperature and humidity measurement sensor inside the optical cell, the temperature and humidity changes of the optical cell can be measured, and correction compensation of temperature and humidity parameters can be performed on the light intensity-concentration model to solve the influence of temperature and humidity on the sample gas concentration value under non-condensing conditions in practical applications.

[0049] More specifically, as above, the national standard gas concentration is dry basis, and the humidity requirement in the standard gas is ≤ 4 °C dew point. In practice, the dry basis requirement may not be met. Measure the actual humidity and perform 1 / (1 - x), where x is the measured humidity value, to perform dry basis conversion on the measurement value. If the humidity interferes with the sample gas measurement value, the humidity factor of the model can also be corrected according to the influence of different humidities on the light intensity at the same concentration.

[0050] Step S6, data processing and concentration calculation: including signal control circuit board operation: (1) Process and analyze the electrical signals collected by all sensors.

[0051] (2) Execute the algorithms related to Lambert-Beer's law, establish a mathematical model between light intensity and gas concentration. According to Lambert-Beer's law, the light intensity is directly proportional to the gas concentration. By establishing a light intensity change model of the first light beam at different gas concentrations, the gas concentration entering the measurement gas chamber can be calculated.

[0052] Through the functional relationship or curve relationship between the second light intensities, the concentration of the target gas to be measured in the sample gas is further obtained. Among them, the second light intensity is not affected by the gas concentration. Therefore, theoretically, the value of the second light intensity is stable and unchanged. However, due to factors such as the use environment or light source drift and attenuation, there will be a systematic light intensity drift change independent of the gas concentration change. Use the change amount of the second light intensity to eliminate the influence of light source drift on the measurement value of the detector at the measurement end, so that the detector at the measurement end can more accurately reflect the corresponding relationship between gas concentration and light intensity, and provide a reference point signal for the overall zero calibration and range calibration of the instrument. For example, when high-purity nitrogen is introduced into the optical cell, record the signal intensities of the second light intensity and the first light intensity, and record the light intensity difference between the two, which is the zero value, and analyze the zero light intensity reference point of the overall instrument; when introducing the range standard gas, record the signal intensities of the second light intensity and the first light intensity, and record the light intensity difference between the two, which is the full point, and analyze the full point light intensity reference point of the overall instrument; in this way, the range of different standard gases in the analysis instrument is expanded, and the influence of light source drift and attenuation is avoided.

[0053] Concentration calculation: According to the light intensity difference detected by the measurement end and the reference end, combined with the known environmental conditions and gas characteristics, use algorithms to calculate the concentration of the gas to be measured.

[0054] The formula is expressed as: , where A is the absorbance, ε is the molar absorptivity, l is the optical path length, and c is the gas concentration. The gas concentration c can be obtained by inverting this formula.

[0055] Step S5, System calibration and maintenance: Regularly perform system calibration to ensure the accuracy and reliability of long-term use. The calibration process may involve using gas standard samples with known concentrations to adjust the readings of the detector.

[0056] In summary, the device of the present invention can effectively calculate the concentration of the target gas to be measured in the sample gas by precisely controlling and measuring the intensity change of the light beam after passing through the gas to be measured, and combining the real-time monitoring and compensation of environmental parameters. This method has high sensitivity and good accuracy, and is widely used in fields such as environmental monitoring and industrial production.

[0057] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by terms such as "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention.

[0058] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. Without departing from the spirit and scope of the present invention, various changes and improvements will occur to the present invention, and all such changes and improvements fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A gas concentration analysis device based on high temperature optical principle, comprising a device body, characterized in that: The device body comprises: a light source (1), an optical beam splitter (2), a measuring light pool (3), a high temperature resistant light guide column (4), a measuring end detector (5), and a reference end detector (6); The high temperature resistant light guide column (4) comprises a first light guide column (401) and a second light guide column (402), wherein the first light guide column (401) and the second light guide column (402) are respectively located on two sides of the measuring light pool (3); The light source (1) is connected to a light source beam splitter (2) and is split into a first light beam (101) and a second light beam (102) by the light source beam splitter (2); the terminal of the first light beam (101) passes through a first light guide column (401), a measuring light pool (3) and a second light guide column (402) in sequence and is connected to a measuring end detector (5); the terminal of the second light beam (102) is connected to a reference end detector (6); The first light guide column (401) and the second light guide column (402) are made of light-transmitting clean quartz glass; The measuring light pool (3) is a small air chamber for storing the gas to be measured and is provided with an air inlet (10) and an air outlet (11). Both ends of the measuring light pool (3) are sealed with optical glass.

2. A gas concentration analysis device based on high temperature optical principle according to claim 1, characterized in that: The device body further comprises a pressure sensor, a temperature and humidity sensor (7), and a signal control circuit board (8); the pressure sensor, the temperature and humidity sensor (7) and the signal control circuit board (8) are connected via line signals; The light source (1), the optical beam splitter (2), the measuring end detector (5) and the reference end detector (6) are all connected to the signal control circuit board (8) via wired signals.

3. A gas concentration analysis device based on high temperature optical principle according to claim 2, characterized in that: The signal control circuit board (8) is used to control the electrical signal of the device body, including: high-frequency modulation of the light source, constant temperature control of the system, acquisition and processing of the measurement end detector signal, acquisition and processing of the reference end detector signal, acquisition and processing of the pressure sensor signal, acquisition and processing of the temperature and humidity sensor signal, operation of the light intensity and concentration model algorithm, and one or more of the system calibration operations.

4. The gas concentration analysis device based on high temperature optical principle according to claim 1, characterized in that: A narrow-band filter is placed between the second light guide column (402) and the measuring end detector (5).

5. The gas concentration analysis device based on high temperature optical principle according to claim 1, characterized in that: A constant temperature purge fan for cooling the first light guide column (401) and the second light guide column (402) is also placed outside the first light guide column (401) and the second light guide column (402).

6. The gas concentration analysis device based on high temperature optical principle according to claim 1, characterized in that: The measuring end detector (5) is used to measure the intensity of a first light beam formed by the light beam emitted by the light source (1) passing through the optical beam splitter (2) and then passing through the measuring light pool (3); the reference end detector (6) is used to measure the second light intensity of a second light beam formed by the light beam emitted by the light source (1) passing through the optical beam splitter (2).

7. A gas concentration analysis device based on high temperature optical principle according to claim 1, characterized in that: A narrow-band filter corresponding to the measuring light pool (3) is placed between the second light guide column (402) and the measuring end detector (5).

8. The gas concentration analysis device based on high temperature optical principle according to claim 3, characterized in that: The operation of the concentration model algorithm includes: obtaining a functional relationship or a curve relationship between the light intensity signals at the measuring end and the reference end by comparing the light intensity signals at the measuring end and the reference end; and calculating the concentration of the target gas to be measured in the sample gas by combining the Lambert-Beer law and the compensated light intensity data.

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