CN110057779B - Method and device for measuring gas concentration based on temperature automatic compensation TDLAS technology - Google Patents
Method and device for measuring gas concentration based on temperature automatic compensation TDLAS technology Download PDFInfo
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Abstract
The invention relates to a method and a device for measuring gas concentration based on a temperature automatic compensation TDLAS technology, wherein the method comprises the following steps of firstly, setting a standard probe and a detection probe, wherein the standard probe is filled with standard gas, and the gas in the measurement probe is the gas in a gas source to be measured; placing a standard probe and a measuring probe in a gas source to be measured; secondly, adjusting the parameters of the tunable narrow-linewidth laser according to the characteristic spectral line of the gas molecule to be detected, and ensuring that the scanning wavelength range of the tunable narrow-linewidth laser only covers one characteristic spectral line of the gas molecule to be detected; then, splitting the tunable narrow linewidth laser beam and simultaneously irradiating the gas in the standard probe and the gas in the measuring probe respectively; and finally, acquiring the laser intensity of the standard probe and the measuring probe, and calculating to obtain the concentration of the gas to be measured. The invention does not need to fit and calculate the intensity of the absorption line at different temperatures in advance, does not need to measure the temperature of the measured gas in real time, and can accurately measure the concentration of the measured gas at different temperatures.
Description
Technical Field
The invention relates to the technical field of gas concentration measurement by a spectrum adsorption method, in particular to a method and a device for measuring gas concentration based on a temperature automatic compensation TDLAS technology.
Background
The Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology is used for measuring the gas concentration, based on the narrow line width (about 2MHz) and the wavelength quick tuning characteristic (up to 100KHz) of a diode laser, by scanning the characteristic spectral line of the gas to be measured, the light intensity change before and after the gas absorption is measured, and the concentration of the gas to be measured is calculated. Because the line width of the laser is far smaller than the width of the absorption spectrum line of the gas to be detected, the laser can be accurately controlled in a selected spectral range when the absorption line is scanned, the interference of the absorption spectrum of other gases is avoided, and the accurate measurement of the gas concentration in a complex environment is realized.
In 2008, Li Yunqing et al, in the journal paper of light metals, "application of hydrogen fluoride gas on-line detection technology in aluminum electrolysis purification", disclose a method and apparatus, the method uses TDLAS technology to detect the concentration of HF gas in the tail gas of aluminum electrolysis industry in real time, uses automatic calibration technology, and uses reference light to eliminate the influence of zero point and range drift caused by dust, light source and other factors, but does not correct the temperature, and because the absorption line intensity (S (T)) is related to the temperature of the gas to be measured, the temperature change can bring about measurement error.
Nobody of 2017 discloses a method in "spectroscopy and spectral analysis" journal paper "research on high-temperature HF gas detection method based on laser technology combined with temperature correction", which calibrates the intensity (s (t)) of an absorption line by selecting a finite temperature value, and fits s (t) values at different temperatures, so as to calculate the HF gas concentration at different temperatures in an inversion manner, but the number of calibrated points limits, and the s (t) value obtained by fitting has an error from a true value, so that the measured value is inaccurate; it is also necessary to obtain the temperature of the gas to be measured at the same time.
Disclosure of Invention
In order to accurately measure the gas concentration at different temperatures, the invention provides a method and a device for measuring the gas concentration based on the temperature automatic compensation TDLAS technology, and the temperature of the measured gas is not required to be known in the measuring process. The method can be used for measuring the concentration of HF gas in a discharge-initiated non-chained HF laser.
Since the TDLAS technology measures the gas concentration according to the beer-Lambert law, the concentration n of the measured gas can be obtained according to the formula (2).
Wherein I0The intensity of the laser light which is not absorbed by the gas, I is the intensity of the laser light absorbed by the gas, and n is the number density (molecule/cm) of the molecules to be detected3) S (T) and phi (v) are respectively the intensity (cm/mole) and the linear function (cm) of an absorption line, L is the propagation distance (cm) of the laser in an absorption medium, and v is the laser wavelength (cm)-1) From equation (2), it can be seen that the gas concentration n is a function of the temperature T, and the temperature term is introduced only by the intensity of the absorption line s (T).
Based on the above analysis, the technical scheme of the invention is as follows:
the method for measuring the gas concentration based on the temperature automatic compensation TDLAS technology comprises the following steps:
step one, setting a standard probe, wherein standard gas is filled in the standard probe, and the standard gas contains gas to be detected with known concentration;
setting a measuring probe, wherein gas in the measuring probe is gas in a measured gas source, and the gas in the measured gas source can freely enter and exit the measuring probe;
placing a standard probe and a measuring probe in a gas source to be measured; ensuring that the temperatures of the standard gas source and the measured gas source are the same;
secondly, adjusting tunable narrow-line width laser parameters according to the characteristic spectral line of the gas molecule to be detected, and ensuring that the scanning wavelength range of the tunable narrow-line width laser only covers one characteristic spectral line of the gas molecule to be detected;
step three, splitting the tunable narrow linewidth laser beam in the step two, and respectively and simultaneously irradiating the gas in the standard probe and the gas in the measuring probe;
step four, collecting the laser intensity passing through the standard probe and the measuring probe, and calculating to obtain the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Is the concentration of the gas to be measured in the standard gas source, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0Is the propagation distance (cm), L of laser in standard gas source1Is the propagation distance (cm) of the laser in the gas source to be measured.
The invention also provides a device for measuring gas concentration based on the temperature automatic compensation TDLAS technology, which is characterized in that: the device comprises a laser source, a beam splitter, a standard probe, a measuring probe, a signal processing system and a controller;
the standard probe comprises a sealed gas absorption cell, and the sealed gas absorption cell is used for filling standard gas, wherein the standard gas comprises gas to be detected with known concentration; the measuring probe comprises a gas absorption pool, and a vent hole is formed in the gas absorption pool to ensure that the gas in the probe is consistent with the gas state of the measured environment; during measurement, the standard probe and the measuring probe are both positioned in a measured gas source; the gas temperature in the standard probe and the gas temperature in the measuring probe are the same;
the output end of the laser source is connected with the input end of the beam splitter, the two output ends of the beam splitter are respectively connected with the input ends of the standard probe and the measuring probe, and the output ends of the standard probe and the measuring probe are connected with the input end of the signal processing system; the controller is respectively connected with the signal processing system and the laser source; the controller is used for controlling the laser and the signal processing system and completing human-computer interaction.
The laser source outputs tunable narrow-linewidth laser, the scanning wavelength range of the tunable narrow-linewidth laser only covers one characteristic spectral line of the gas to be measured, the tunable narrow-linewidth laser is divided into two paths of optical signals after passing through the beam splitter, one path of optical signals is transmitted to the standard probe, and the other path of optical signals is transmitted to the measuring probe; the optical signal is transmitted to a signal processing system by an optical fiber after being absorbed by gas in a standard probe and a measuring probe, a computer program is stored in the signal processing system, and when the computer program runs in a processor, the following processes are realized:
measuring the laser intensity of the measured probe and the standard probe, and calculating the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Is the concentration of the gas to be measured in the standard probe, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0Is the propagation distance (cm), L of laser light in a standard probe1Is the propagation distance (cm) of the laser in the measuring probe.
Further, the signal processing system comprises a data processing unit and two photodetectors; the two photoelectric detectors are respectively used for measuring optical signals output by the standard probe and the measuring probe, converting the optical signals into electric signals and sending the electric signals to the data processing unit, and the computer program is stored in the data processing unit.
Further, the laser source is a solid laser, a fiber laser or a semiconductor laser; adopting an optical fiber output mode; the beam splitter is an optical fiber beam splitter.
Furthermore, the standard probe also comprises an optical fiber collimator and an optical fiber coupler which are arranged at two opposite ends of the sealed gas absorption pool, laser enters the optical fiber collimator through an optical fiber and is transmitted to the optical fiber coupler through mixed gas, and the optical fiber coupler is connected with the input end of the signal processing system through the optical fiber;
the measuring probe also comprises an optical fiber collimator and an optical fiber coupler which are arranged at the two opposite ends of the gas absorption pool, laser enters the optical fiber collimator through an optical fiber and then is transmitted to the optical fiber coupler through mixed gas, and the optical fiber coupler is connected with the input end of the signal processing system through the optical fiber.
Furthermore, the measuring probe and the standard probe are arranged on the same flange; the standard probe and the measuring probe are hermetically connected with a gas source to be measured through a flange;
the input and output optical fibers used by the measuring probe are consistent in length with those used by the standard probe.
Furthermore, in order to facilitate the standard gas filling, the sealed gas absorption pool of the standard probe is also provided with a gas inlet pipe communicated with the outside, and the gas inlet pipe is provided with a gas stop valve.
Furthermore, the gas to be detected is HF, the tunable narrow linewidth laser output wavelength output by the laser source is near 1.3 μm, the output wavelength is continuously adjustable, the adjusting frequency can reach 100kHz, and the linewidth is about 2 MHz;
the invention also provides a method for measuring gas concentration by using the device, which comprises the following steps:
s1, installing a standard probe and a measuring probe in the device for measuring the gas concentration based on the temperature automatic compensation TDLAS technology on a gas source to be measured, and ensuring that the gas temperature in the measuring probe and the gas temperature in the standard probe are at the same temperature;
s2, filling standard gas with known concentration to-be-detected gas into the standard probe;
s3, starting a laser source, adjusting laser source parameters according to the characteristic spectral line of the gas molecules to be detected, and ensuring that the scanning wavelength range of the laser source only covers one characteristic spectral line of the gas molecules to be detected;
s4, measuring the laser intensity passing through the measuring probe and the standard probe, and calculating to obtain the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Indicating the gas concentration in the reference probe, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0For the propagation distance of the laser in a standard probe, L1Is the propagation distance of the laser in the measuring probe.
Further, the method also includes step S5: and (4) displaying and outputting the measured gas concentration curve through a controller.
The invention has the following beneficial effects:
1. the invention can carry out real-time online calibration on the measured gas concentration measurement without drift of zero point and measuring range by arranging the calibration probe in the measured gas source.
2. The calibration probe and the measured gas are at the same temperature, the intensity of absorption lines at different temperatures does not need to be calculated in advance in a fitting manner, the temperature of the measured gas does not need to be measured in real time, and the concentration of the measured gas at different temperatures can be accurately measured.
3. The invention designs the integrated probe, and the measuring probe and the calibration probe adopt an integrated structure, thereby reducing the workload of installation, debugging and maintenance.
4. The invention is suitable for different temperature and pressure environments and has wide application range.
Drawings
FIG. 1 is a schematic structural diagram of a measuring apparatus in the embodiment;
FIG. 2 is a schematic structural diagram of a measurement probe in an embodiment;
FIG. 3 is a schematic structural diagram of a calibration probe in the embodiment;
FIG. 4 is a schematic diagram of an embodiment of a signal processing system;
the reference signs are: 1-a controller; 2-a laser source; 3-a beam splitter; 4-measuring the probe; 5-a standard probe; 6-a signal processing system; 7-measured air source chamber; 8-probe interface;
41-a gas absorption cell; 42-a vent hole; 43. 52-fiber collimator; 44. 53-fiber coupler; 45. 54-a flange; 51-sealing the gas absorption cell; 55-metal gas pipe; 56-gas shut-off valve; 61-a data processing unit; 62-photodetector.
Detailed Description
The invention is further described with reference to the following figures and specific embodiments.
According to the invention, through analysis of the relation between the temperature and the gas concentration, the temperature term is only introduced by the intensity S (T) of the absorption line. Therefore, the invention can carry out real-time online calibration on the concentration measurement of the gas to be measured without drift of zero point and measuring range by arranging the calibration gas source in the gas source to be measured.
The method is realized by the following steps:
step one, setting a standard probe, and filling standard gas with gas to be detected into the standard probe, wherein the concentration of the gas to be detected is known;
setting a measuring probe, wherein gas in the measuring probe is gas in a measured gas source, and the gas in the measured gas source can freely enter and exit the measuring probe;
placing a standard probe and a measuring probe in a gas source to be measured; ensuring that the temperatures of the standard gas source and the measured gas source are the same;
secondly, adjusting tunable narrow-line width laser parameters according to the characteristic spectral line of the gas molecule to be detected, and ensuring that the scanning wavelength range of the tunable narrow-line width laser only covers one characteristic spectral line of the gas molecule to be detected;
step three, utilizing the tunable narrow linewidth laser parameters of the step two to split beams and respectively and simultaneously irradiate the gas in the standard probe and the gas in the measuring probe;
step four, collecting the laser intensity passing through the standard probe and the measuring probe, and calculating to obtain the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Is the concentration of the gas to be measured in the standard gas source, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0Is the propagation distance (cm), L of laser in standard gas source1Is the propagation distance (cm) of the laser in the gas source to be measured.
The method is suitable for measuring CO by TDLAS technology2、HCl、CH4And H2Gases such as O vapor, the gas to be measured in the following examples is described by taking HF as an example, and the gas source chamber to be measured may be regarded as an HF laser chamber, for example, as a mixed gas containing HF gas of unknown concentration.
The present embodiment discloses an apparatus for implementing the above method, and as can be seen from fig. 1, the measuring apparatus mainly includes a laser source 2, a beam splitter 3, a measuring probe 4, a standard probe 5, a signal processing system 6 and a controller 1.
When the measured gas source operates, the trigger end outputs TTL signals to trigger the controller 1, and the controller 1 controls the laser source 2 and the signal processing system 6 to operate synchronously. The laser source 2 outputs tunable narrow linewidth laser, the laser is divided into 2 paths of optical signals after passing through the beam splitter 3, one path of optical signals is transmitted to the standard probe 5, the other path of optical signals is transmitted to the measuring probe 4, the optical signals output by the standard probe 5 and the measuring probe 4 are transmitted to the signal processing system 6 through optical fibers, and the photoelectric detector in the signal processing system converts the optical signals into electric signals to be processed, so that the concentration of the gas to be measured is obtained and displayed and output.
The controller 1 is used for realizing man-machine interaction of the measuring device, setting and controlling the semiconductor tunable narrow linewidth laser 2 and the signal processing system to operate according to requirements, and simultaneously outputting and displaying a measured concentration result. The laser source 2 can be selected from a solid laser, a fiber laser, a semiconductor laser and the like, the embodiment selects a semiconductor tunable narrow linewidth laser, an optical fiber output mode is adopted, an optical fiber interface is of an FC type, the output wavelength is near 1.3 mu m, the adjustment frequency can reach 100kHz, and the linewidth is about 2MHz, and is continuously adjustable. The injection current of the diode laser is tuned by adopting sawtooth wave voltage (frequency is 5kHz, amplitude is 2V) to enable the diode laser to scan at the frequency of 5kHz at 0-80 mA, and therefore the diode laser outputs an absorption spectral line (1330.529nm) with the wavelength repeatedly scanned and selected at the frequency of 5 kHz.
The beam splitter 3 is an optical fiber beam splitter, the input end of the optical fiber beam splitter is connected with the semiconductor tunable narrow-linewidth laser, the output ends of the optical fiber beam splitter are two optical fiber output ports, laser signals are respectively transmitted to the standard probe and the measuring probe, and the interface is an FC type optical fiber interface.
As can be seen from fig. 2, the measuring probe 4 is composed of a corrosion-resistant gas absorption cell 41, a fiber collimator 43, a fiber coupler 44, and a flange 45. In order to facilitate full contact with the gas to be detected, a large number of vent holes 42 are distributed around the gas absorption cell, and an optical fiber collimator 43 and an optical fiber coupler 44 are arranged at two ends of the upper gas absorption cell according to a set light path, so that the laser is ensured to be emitted from the optical fiber collimator 43 and transmitted to the optical fiber coupler 44 after passing through the gas to be detected. The flange 45 is used for fixing the measuring probe 4, is arranged at the connecting port 8 of the measured air source cavity 7 and is connected with the measured air source cavity 7 in a sealing mode.
As can be seen from fig. 3, the standard probe 5 comprises a sealed gas absorption cell 51, a fiber collimator 52, a fiber coupler 53, a flange 54, a metal gas pipe 55, and a gas stop valve 56. The sealed gas absorption cell 51 is a metal cavity subjected to hydrogen fluoride passivation treatment, and the wall thickness is 1 mm; it is filled with HF and He mixed gas, the concentration of HF gas is n0The optical fiber collimator 52 and the optical fiber coupler 53 are installed at two ends of the upper gas absorption cell according to a set optical path, so that the laser is ensured to be emitted from the optical fiber collimator 52 and transmitted to the optical fiber coupler 53 after passing through the standard gas. The metal gas pipe 55 is communicated with the gas absorption cell 51 through a flange 54 and is used for filling and extracting standard gas in the sealed gas absorption cell, and the metal gas pipe 55 is communicated with a pump and the standard gas through a gas stop valve 56The air source and other external devices are connected; the flange 54 fixes the standard probe at the connecting port 8 of the measured air source cavity 7, and the standard probe is connected in a sealing mode. The fiber collimator and the fiber coupling both adopt fiber FC type ports.
The measuring probe 4 and the standard probe 5 are integrally designed and are arranged on the same metal flange, so that the space difference between the measuring probe 4 and the standard probe 5 is as small as possible while the installation is convenient and the maintenance is reduced, and the measuring error caused by the temperature difference caused by the space difference is reduced. In addition, the length of the input/output optical fiber used by the measuring probe 4 is consistent with that of the input/output optical fiber used by the standard probe 5, so that errors caused by transmission loss are avoided.
As can be seen from fig. 4, the signal processing system 6 comprises two parts, a photodetector 62 and a data processing unit 61. The photoelectric detector consists of two DET50B photoelectric detectors, which are respectively used for measuring the laser intensity absorbed by the standard probe 5 and the measuring probe 4, and are respectively connected with the standard probe and the measuring probe by optical fibers, and the interface is an FC type optical fiber interface. The data processing unit consists of a circuit system for collecting, storing and completing program calculation, and has the main functions of collecting, storing and calculating data output by the photoelectric detector module and then transmitting the result to the controller. During calculation, the concentration n of the measured gas is calculated according to the formula (1)1；
Wherein n is0Is the concentration of the gas to be measured in the standard probe, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0Is the propagation distance (cm), L of laser light in a standard probe1Is the propagation distance (cm) of the laser in the measuring probe.
When the HF concentration is measured, the operation steps are as follows:
1. the measuring probe and the standard probe are adjacently arranged on a gas source to be measured, so that the temperature of gas in the measuring probe and the temperature of gas in the standard probe are ensured to be at the same temperature;
2. for standard probeThe filling concentration in the head is n0HF standard gas of (1).
3. And starting the semiconductor tunable laser, and selectively marking the characteristic spectral line of the HF molecule to ensure that the scanning wavelength range of the semiconductor tunable laser only covers one characteristic spectral line of the HF molecule. Since the TDLAS technology for measuring the HF gas concentration obeys beer-Lambert law, the concentration n of the measured HF gas can be obtained according to the formula (2).
Wherein I0The intensity of laser light which is not absorbed by HF gas, I is the intensity of laser light absorbed by HF gas, and n is the number density (molecule/cm) of HF molecules3) S (T) and phi (v) are respectively the intensity (cm/mole) and the linear function (cm) of an absorption line, L is the propagation distance (cm) of the laser in an absorption medium, and v is the laser wavelength (cm)-1). From equation (2) it can be seen that the gas concentration n is a function of the temperature T and that the temperature term is only introduced by the intensity of the absorption line s (T).
4. Measuring the laser intensity of the measured gas and the standard probe, wherein the standard probe has the same temperature as the measured gas, and the absorption line intensity S (T) is the same, and calculating the concentration n of the measured gas according to the formula (1) by using the laser intensity change after passing through the standard probe and the measuring probe1Wherein n is0Indicating the concentration of gas in the standard probe.
5. And (4) displaying and outputting the measured HF gas concentration curve through a controller.
The invention is not limited to the above embodiments, such as the shape structure and material of the gas absorption cell in the standard probe and the measurement probe, the type selection of the photoelectric detector, the optical fiber material, the core diameter, the length and the interface, etc., the pipe diameter and the size of the metal gas pipe, etc.
Claims (8)
1. Device based on gas concentration is measured to temperature automatic compensation TDLAS technique, its characterized in that: the device comprises a laser source (2), a beam splitter (3), a standard probe (5), a measuring probe (4), a signal processing system (6) and a controller (1); the measuring probe and the calibration probe adopt an integrated structure;
the standard probe (5) comprises a sealed gas absorption cell (51), the sealed gas absorption cell (51) is used for filling standard gas, and the standard gas comprises gas to be detected with known concentration; the measuring probe (4) comprises a gas absorption cell (41), and a vent hole (42) is formed in the gas absorption cell (41); during measurement, the standard probe (5) and the measuring probe (4) are both positioned in a gas source to be measured; the standard probe (5) and the measuring probe (4) have the same gas temperature;
the output end of the laser source (2) is connected with the input end of the beam splitter (3), the two output ends of the beam splitter (3) are respectively connected with the input ends of the standard probe (5) and the measuring probe (4), and the output ends of the standard probe (5) and the measuring probe (4) are both connected with the input end of the signal processing system (6); the controller (1) is respectively connected with the signal processing system (6) and the laser source (2), and is used for controlling the laser device and the signal processing system and completing human-computer interaction;
the measuring probe (4) and the standard probe (5) are arranged on the same flange; the standard probe (5) and the measuring probe (4) are hermetically connected with a gas source cavity to be measured through flanges;
the length of the input and output optical fibers used by the measuring probe (4) and the standard probe (5) is consistent;
the laser source (2) outputs tunable narrow-linewidth laser, the scanning wavelength range of the tunable narrow-linewidth laser only covers one characteristic spectral line of the gas to be measured, the tunable narrow-linewidth laser is divided into two paths of optical signals after passing through the beam splitter (3), one path of optical signals is transmitted to the standard probe (5), and the other path of optical signals is transmitted to the measuring probe (4); the optical signal is transmitted to a signal processing system (6) through an optical fiber after being absorbed by gas in a standard probe (5) and a measuring probe (4), a computer program is stored in the signal processing system (6), and when the computer program runs in a processor, the following processes are realized:
measuring the laser intensity of the measured probe and the standard probe, and calculating the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Is the concentration of the gas to be measured in the standard probe, A0The intensity of the laser light passing through the standard probe, A1Is the laser intensity after passing through the measuring probe, L0Is the propagation distance (cm), L of laser light in a standard probe1Is the propagation distance (cm) of the laser in the measuring probe.
2. The apparatus for measuring gas concentration based on the temperature auto-compensation TDLAS technique as claimed in claim 1, wherein: the signal processing system (6) comprises a data processing unit (61) and two photodetectors (62); the two photoelectric detectors (62) are respectively used for measuring optical signals output by the standard probe (5) and the measuring probe (4), converting the optical signals into electric signals and sending the electric signals to the data processing unit (61), and the computer program is stored in the data processing unit (61).
3. The apparatus for measuring gas concentration based on the temperature auto-compensation TDLAS technique as claimed in claim 2, wherein: the laser source (2) is a solid laser, a fiber laser or a semiconductor laser; adopting an optical fiber output mode; the beam splitter (3) is an optical fiber beam splitter.
4. The apparatus for measuring gas concentration based on the temperature auto-compensation TDLAS technique as claimed in claim 3 wherein:
the standard probe (5) further comprises an optical fiber collimator (52) and an optical fiber coupler (53) which are arranged at two opposite ends of the sealed gas absorption cell (51), laser enters the optical fiber collimator (52) through an optical fiber and then is transmitted to the optical fiber coupler (53) through standard gas, and the optical fiber coupler (53) is connected with the input end of the signal processing system (6) through the optical fiber;
the measuring probe (4) further comprises an optical fiber collimator (43) and an optical fiber coupler (44) which are arranged at two opposite ends of the gas absorption cell (41), laser enters the optical fiber collimator (43) through an optical fiber and is transmitted to the optical fiber coupler (44) through mixed gas, and the optical fiber coupler (44) is connected with the input end of the signal processing system (6) through the optical fiber.
5. The apparatus for measuring gas concentration based on the temperature auto-compensation TDLAS technique as claimed in claim 4 wherein:
the sealed gas absorption pool of the standard probe is also provided with a gas inlet pipe communicated with the outside, and the gas inlet pipe is provided with a gas stop valve.
6. The apparatus for measuring gas concentration based on the temperature auto-compensation TDLAS technique as claimed in any of claims 1 to 5 wherein: the gas to be detected is HF, the tunable narrow-linewidth laser output wavelength output by the laser source is 1.3 mu m, the adjusting frequency is 100kHz, and the linewidth is 2 MHz.
7. A method of measuring the concentration of a gas using the apparatus of any one of claims 1 to 6, comprising the steps of:
s1, installing a standard probe and a measuring probe in the device for measuring the gas concentration based on the temperature automatic compensation TDLAS technology on a gas source to be measured, and ensuring that the gas temperature in the measuring probe and the gas temperature in the standard probe are at the same temperature;
s2, filling standard gas with known concentration to-be-detected gas into the standard probe;
s3, starting a laser source, adjusting laser source parameters according to the characteristic spectral line of the gas molecules to be detected, and ensuring that the scanning wavelength range of the laser source only covers one characteristic spectral line of the gas molecules to be detected;
s4, measuring the laser intensity passing through the measuring probe and the standard probe, and calculating to obtain the concentration n of the measured gas according to the formula (1)1；
Wherein n is0Indicating the gas concentration in the reference probe, A0Is passing throughLaser intensity behind the standard probe, A1Is the laser intensity after passing through the measuring probe, L0For the propagation distance of the laser in a standard probe, L1Is the propagation distance of the laser in the measuring probe.
8. The method according to claim 7, further comprising step S5: and (4) displaying and outputting the measured gas concentration curve through a controller.
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