CN114965335A - Remote laser optical fiber gas detection system and method thereof - Google Patents

Remote laser optical fiber gas detection system and method thereof Download PDF

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Publication number
CN114965335A
CN114965335A CN202110202667.XA CN202110202667A CN114965335A CN 114965335 A CN114965335 A CN 114965335A CN 202110202667 A CN202110202667 A CN 202110202667A CN 114965335 A CN114965335 A CN 114965335A
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gas detection
detector
optical fiber
laser
fiber
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邵伟珂
汤婷婷
邵琳凯
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Beijing Ditrui Technology Co ltd
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Beijing Ditrui Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
    • G01N21/3504—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing gases, e.g. multi-gas analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters

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  • Spectroscopy & Molecular Physics (AREA)
  • Health & Medical Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
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  • Investigating Or Analysing Materials By Optical Means (AREA)

Abstract

The invention belongs to the technical field of gas detection, and particularly relates to a remote laser optical fiber gas detection system which comprises a laser transmitter, an input optical fiber and a gas detection pool arranged at a point to be detected; the laser emitter is connected with one end of an input optical fiber, the other end of the input optical fiber is connected with the inlet end of a gas detection pool, and the outlet end of the gas detection pool is provided with a detector; the invention avoids the defects of poor operability and high danger coefficient caused by adopting an expensive online monitoring system or needing manpower to reach a position which is difficult to reach.

Description

Remote laser optical fiber gas detection system and method thereof
Technical Field
The invention belongs to the technical field of gas detection, and particularly relates to a remote laser optical fiber gas detection system.
Background
1, many fixed gas emission sources in China have the problem of being difficult to monitor at present, and the problems that the fixed gas emission sources cannot climb or professional large-scale monitoring instruments cannot easily reach a sampling platform and the like are solved. A large number of pollution source discharge ports scattered about small enterprises do not have good test conditions. Very much pollutant information is obtained without any benefit, and the method is in the supervision blank.
In recent years, optical fiber technology has developed rapidly. The sensing measurement system based on the optical fiber structure has been widely applied to industrial production due to the outstanding advantages of low transmission loss, electromagnetic interference resistance, flexible transmission, low cost and the like. The optical fiber technology is applied to monitoring of gas pollutants, concentration detection of different types of gases at special point positions can be achieved, and remote online testing is expected to be achieved.
And 3, through the use of devices such as a quantum cascade laser, a low-loss optical fiber, a high-sensitivity gas detection cell, a mid-infrared detector and the like, the remote gas measurement can be realized. The light emitted by the laser is coupled to a low loss optical fiber and transmitted over long distances in the optical fiber. Optical fiber can be through unmanned aerial vehicle, carrying devices such as tower crane, transmit near gas discharge port with laser. A high-sensitivity gas detection cell is arranged at the tail end of optical fiber transmission, laser is subjected to gas absorption reaction, part of the absorbed laser is transmitted back to the ground through low-loss optical fiber transmission again, and a returned light intensity signal is analyzed by a detector, so that remote testing is realized. The system which has high energy consumption and needs refrigeration, such as a laser, a detector and the like, can be placed at a proper position far away from a detection point, and only a high-sensitivity gas detection pool, necessary optical components and optical fibers are positioned at a remote test point.
4, through above device, can realize the test work of many types of gas remotely. Meanwhile, the advantages of low cost, flexible transmission, in-situ measurement and the like can be met, and the method is a comprehensive optimal solution for cost and technology under the current technical condition.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a remote laser optical fiber gas detection system.
The technical scheme of the invention is realized as follows:
a remote laser optical fiber gas detection system comprises a laser transmitter, an input optical fiber and a gas detection pool arranged at a point to be detected; the laser emitter is connected with one end of an input optical fiber, the other end of the input optical fiber is connected with the inlet end of a gas detection pool, and the outlet end of the gas detection pool is provided with a detector.
Furthermore, the detector is carried on the unmanned aerial vehicle, transported to a point to be measured and connected with the outlet end of the gas detection pool.
Furthermore, the outlet end of the gas detection cell is provided with one end of an output optical fiber, and the other end of the output optical fiber is provided with a detector.
Further, the input optical fiber and the output optical fiber are both low-loss optical fibers.
Further, the laser emitter is any one of a quantum cascade laser, a distributed feedback laser and a grating laser.
Further, the detection cell is any one of an open optical path detection cell, a reflection optical path detection cell or a removable gas detection cell.
Furthermore, the detector is any one of a mercury cadmium telluride detector, an indium arsenic antimony detector, an indium gallium arsenic detector, an indium aluminum arsenic detector and an indium phosphide detector.
The working principle and the effect of the scheme are as follows:
the method adopts mid-infrared lasers including but not limited to quantum cascade lasers, including distributed feedback lasers, grating lasers and the like, and the characteristic gas has fingerprint characteristic absorption in the waveband. For example: CO 2 2 At 4.3 μm, CO at 4.5 μm, NO at 5.2 μm, NO 2 At 6.1 μm, SO 3 At 7.2 μm, SO 2 At 7.4 μm, CH 4 At 7.48 μm, NH 3 At 9.0 μm, O 3 There was an absorption at 9.6 μm.
And 2, selecting optical fibers doped with sulfur series and halogen series, hollow optical fibers or other different types of low-loss optical fibers which can be used for transmission, and adopting optical fibers with low transmission loss of optical signals in the mid-infrared band.
And 3, the laser emits light with different wavelengths, and the light is remotely transmitted to a gas detection cell through a low-loss optical fiber, including but not limited to an open optical path detection cell, or a reflective multi-optical path detection cell, including but not limited to a Herriot detection cell, so that an optical signal transmitted by an input optical fiber is coupled to an incident end of the gas detection cell, and the optical signal and the gas to be detected in the detection cell perform optical detection, including but not limited to forms of optical absorption, fluorescence or optical scattering and the like.
And 4, coupling the optical signal generated after the gas is absorbed, fluoresced or scattered into an output optical fiber through the light emergent port of the gas detection cell, and remotely transmitting the optical signal to the detector through the output optical fiber. Detectors include, but are not limited to Mercury Cadmium Telluride (MCT), indium arsenic antimony (InAsSb), indium gallium arsenic (InGaAs), indium aluminum arsenic (InAlAs), indium phosphide (InP), etc. detectors, photomultiplier tubes, etc.
This scheme can also directly carry the detector on test platform like unmanned aerial vehicle for the butt joint of detector and gaseous reaction tank output, the light after detection tank and gaseous reaction directly gets into the detector (need not to pass through optical fiber transmission) and converts into forms such as signal of telecommunication.
I.e. the detector may be present at the output of either the remote output fibre or the gas detection cell.
And 5, converting the optical signal into an electric signal by the detector, and differentiating the signals of the absorbed gas and the non-absorbed gas to obtain the signal difference change caused by the gas concentration change. And (5) the concentration of the gas to be detected can be known after the signal value is corresponding to the standard curve.
All the above devices, including but not limited to auxiliary devices and modules such as power supply, refrigeration and the like, realize the detection work of signals together.
And 8, the detection principle is as follows: taking light absorption as an example, according to lambert beer's law a ═ lg (1/T) ═ Kbc, where a represents absorbance, T represents transmittance (transmittance), and the ratio of emitted light intensity (I) to incident light intensity (I0),
k is the molar absorption coefficient, which is related to the nature of the absorbing species and the wavelength λ of the incident light, and c is the concentration of the absorbing species in mol/L.
It is known that the concentration of contaminants in a gas is directly proportional to the absorbance and inversely proportional to the received light absorption signal. By measuring and analyzing the optical signals, the types and emission concentrations of different instantaneous pollutants can be obtained.
By the method, the optical fiber can be distributed in various modes, for example, the optical fiber is arranged above a long-distance high tower, or the optical fiber and the detection pool (and the detector) are lifted by an unmanned aerial vehicle, or the optical fiber is used for a test scene in which the laser/detector needs to be separated from the detection pool, so that the laser/detector can work under a stable condition, and the fixed wavelength test light is led out to a certain area (including a severe environment, a complex condition and the like) through the optical fiber to perform related test work.
The scheme adopts the quantum cascade laser and the low-loss optical fiber, so that most detection work can be easily completed. The risk and inconvenience are effectively avoided, and the method has extremely high economical efficiency. Provides a simple, convenient and effective method for widely developing pollution source general investigation work.
The application requirement of the scheme for gas measurement in the area difficult to reach can be that the optical fiber and the detection cell are installed and tested in a fixed or non-fixed mode, for example: high towers, chimneys, unmanned planes, canyons, and the like.
Because the light propagation property has stability, the light beam is transmitted to the position to be measured for measurement, and compared with the traditional sampling measurement, the method has incomparable advantages and effects.
The problems that an expensive online monitoring system is adopted, or the position which is difficult to reach is reached by manpower, the operability is poor, the danger coefficient is high, and the pollution source monitoring always belongs to the supervision and test technology are avoided.
Drawings
Fig. 1 is a schematic structural diagram of an embodiment 1 of a remote laser fiber gas detection system according to the present invention.
Reference numerals: unmanned aerial vehicle 1, gaseous detection cell 2, input fiber 3, laser emitter 4, detector 5, output fiber 6.
Detailed Description
The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that all the directional indicators (such as upper, lower, left, right, front and rear … …) in the embodiment of the present invention are only used to explain the relative position relationship between the components, the movement situation, etc. in a specific posture (as shown in the drawing), and if the specific posture is changed, the directional indicator is changed accordingly.
In addition, the descriptions relating to "first", "second", etc. in the present invention are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Example 1
As shown in fig. 1, a remote laser optical fiber gas detection system includes a laser transmitter 4, an input optical fiber 3, and a gas detection cell 2 installed at a point to be detected; the laser transmitter 4 is connected with one end of the input optical fiber 3, the other end of the input optical fiber 3 is connected with the inlet end of the gas detection cell 2,
the outlet end of the gas detection cell 2 is provided with one end of an output optical fiber 6, and the other end of the output optical fiber 6 is provided with a detector 5.
Both the input fibre 3 and the output fibre 6 are low loss fibres.
The laser emitter 4 is any one of a quantum cascade laser, a distributed feedback laser and a grating laser.
The detection pool is any one of an open optical path detection pool, a reflective optical path detection pool and a removable gas detection pool.
The detector 5 is any one of a mercury cadmium telluride detector, an indium arsenic antimony detector, an indium gallium arsenic detector, an indium aluminum arsenic detector and an indium phosphide detector.
When specifically building:
the method adopts mid-infrared lasers including but not limited to quantum cascade lasers, including distributed feedback lasers, grating lasers and the like, and the characteristic gas has fingerprint characteristic absorption in the waveband. For example: CO 2 2 At 4.3 μm, CO at 4.5 μm, NO at 5.2 μm, NO 2 At 6.1 μm, SO 3 At 7.2 μm, SO 2 At a temperature of 7.4 μm,CH 4 at 7.48 μm, NH 3 At 9.0 μm, O 3 There was an absorption at 9.6 μm.
And 2, selecting optical fibers doped with sulfur series and halogen series, hollow optical fibers or other different types of low-loss optical fibers which can be used for transmission, and adopting special optical fibers with low transmission loss of intermediate infrared band optical signals.
3, the laser emits light with different wavelengths, the light is remotely transmitted to a gas detection pool 2 through low-loss optical fibers, the gas detection pool 2 is erected at a point to be detected through an unmanned aerial vehicle 1, and a pollution source or gas to be detected at the point to be detected is introduced into the gas detection pool 2; the gas detection cell 2 includes but is not limited to an open optical path detection cell, a removable gas detection cell, or a reflective multi-optical path detection cell, including but not limited to a Herriot detection cell, couples the optical signal transmitted from the input optical fiber 3 to the incident end of the gas detection cell 2, and performs optical detection with the gas to be detected in the gas detection cell 2, including but not limited to light absorption, fluorescence or light scattering and other forms;
and 4, coupling the optical signal generated by the gas after absorbing fluorescence or scattering into an output optical fiber 6 through the light emergent port of the gas detection cell 2, and remotely conducting the optical signal to a detector 5 through the output optical fiber 6. The detectors 5 include, but are not limited to, Mercury Cadmium Telluride (MCT), indium arsenic antimony (InAsSb), indium gallium arsenic (InGaAs), indium aluminum arsenic (InAlAs), indium phosphide (InP), etc. detectors 5, photomultiplier tubes, etc.
The light after the reaction with the gas in the detection cell is transmitted through the optical fiber and enters the detector 5 to be converted into an electric signal.
The detector 5 converts the optical signal into an electrical signal and differentiates the signals of the absorbed gas and the non-absorbed gas, thereby obtaining a change in the difference between the signals due to a change in the concentration of the gas. And (5) the concentration of the gas to be detected can be known after the signal value is corresponding to the standard curve.
All the above devices, including but not limited to auxiliary devices and modules such as power supply, refrigeration and the like, realize the detection work of signals together.
And 8, the detection principle is as follows: taking light absorption as an example, according to lambert beer's law a-lg (1/T) -Kbc, where a is absorbance, T is transmittance (transmittance), and is the ratio of emitted light intensity (I) to incident light intensity (I0),
k is the molar absorption coefficient, which is related to the nature of the absorbing species and the wavelength λ of the incident light, and c is the concentration of the absorbing species in mol/L.
It is known that the concentration of contaminants in a gas is directly proportional to the absorbance and inversely proportional to the received light absorption signal. By measuring and analyzing the optical signals, the types and emission concentrations of different pollutants can be obtained instantly.
9, through above method, can lay optic fibre with multiple mode, place optic fibre in long-distance high tower top, perhaps through unmanned aerial vehicle 1 handling optic fibre and gaseous detection cell, and detector 5, perhaps be used for laser emitter/detector 5 to need with the test scenario of detection cell separation for laser emitter/detector 5 can work under stable condition, and through optic fibre will fix wavelength test light and draw out to certain area outside (including adverse circumstances, complicated condition etc.) carry out relevant test work.
The scheme adopts the quantum cascade laser transmitter and the loss optical fiber, so that most detection work can be easily completed. The risk and inconvenience are effectively avoided, and the method has extremely high economical efficiency. Provides a simple, convenient and effective method for widely developing pollution source general investigation work.
The application requirement of the scheme for gas measurement in the area difficult to reach can be that the optical fiber and the gas detection cell are installed and tested in a fixed or non-fixed mode, for example: tall towers, chimneys, unmanned planes, canyons, and the like; utilize unmanned aerial vehicle can be nimble quick with gaseous detection pond transportation and hover to corresponding pollution sources department and dock.
Because the light propagation property has stability, the light beam is transmitted to the position to be measured for measurement, and compared with the traditional sampling measurement, the method has incomparable advantages and effects.
The defects that an expensive online monitoring system is adopted, or the position which is difficult to reach is required to be reached by manpower, the operability is poor, the danger coefficient is high, and the pollution source monitoring always belongs to the difficult point of supervision and testing technology are overcome.
Example 2
The difference between the embodiment 2 and the embodiment 1 is that in the embodiment 2, the detector 5 is mounted on the unmanned aerial vehicle 1 and transported to a point to be measured, and is connected with the outlet end of the gas detection pool 2.
This scheme is direct to carry the detector on test platform like unmanned aerial vehicle for the butt joint of detector and gaseous detection pond output, the light after detection pond and gaseous reaction directly gets into the detector (need not to pass through optical fiber transmission) and converts into forms such as signal of telecommunication, can select in a flexible way according to the operating mode of difference, simultaneously also can the furthest's of performance unmanned aerial vehicle effect. Utilize unmanned aerial vehicle can carry out nimble debugging to the position of gaseous detection pond and detector, suitability and practicality obtain greatly improving.
Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (7)

1. A remote laser optical fiber gas detection system is characterized by comprising a laser transmitter, an input optical fiber and a gas detection pool arranged at a point to be detected; the laser emitter is connected with one end of an input optical fiber, the other end of the input optical fiber is connected with the inlet end of a gas detection pool, and the outlet end of the gas detection pool is provided with a detector.
2. The remote laser fiber gas detection system of claim 1, wherein the detector is carried on the unmanned aerial vehicle and transported to a point to be detected, and is connected with an outlet end of the gas detection cell.
3. The remote laser fiber gas sensing system of claim 1, wherein the exit end of the gas sensing cell is provided with one end of an output fiber, and the other end of the output fiber is provided with a detector.
4. The remote laser fiber gas detection system of claim 3, wherein the input fiber and the output fiber are low loss fibers.
5. The remote laser fiber gas detection system according to any one of claims 1-4, wherein the laser transmitter is any one of a quantum cascade laser, a distributed feedback laser, and a grating laser.
6. The remote laser fiber gas detection system according to any one of claims 1 to 4, wherein the detection cell is any one of an open optical path detection cell and a reflective optical path detection cell.
7. The remote laser optical fiber gas detection system as claimed in any one of claims 1 to 4, wherein the detector is any one of a mercury cadmium telluride detector, an indium arsenic antimony detector, an indium gallium arsenic detector, an indium aluminum arsenic detector and an indium phosphide detector in the prior art.
CN202110202667.XA 2021-02-23 2021-02-23 Remote laser optical fiber gas detection system and method thereof Pending CN114965335A (en)

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CN202110202667.XA CN114965335A (en) 2021-02-23 2021-02-23 Remote laser optical fiber gas detection system and method thereof

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CN202110202667.XA CN114965335A (en) 2021-02-23 2021-02-23 Remote laser optical fiber gas detection system and method thereof

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CN114965335A true CN114965335A (en) 2022-08-30

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