CN212722599U - Multi-channel gas concentration detection system based on mid-infrared absorption spectrum - Google Patents
Multi-channel gas concentration detection system based on mid-infrared absorption spectrum Download PDFInfo
- Publication number
- CN212722599U CN212722599U CN202021256139.XU CN202021256139U CN212722599U CN 212722599 U CN212722599 U CN 212722599U CN 202021256139 U CN202021256139 U CN 202021256139U CN 212722599 U CN212722599 U CN 212722599U
- Authority
- CN
- China
- Prior art keywords
- module
- gas
- laser
- concentration
- optical switch
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn - After Issue
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 43
- 238000000862 absorption spectrum Methods 0.000 title claims abstract description 15
- 230000003287 optical effect Effects 0.000 claims abstract description 80
- 238000012545 processing Methods 0.000 claims abstract description 32
- 238000009826 distribution Methods 0.000 claims abstract description 19
- 230000003321 amplification Effects 0.000 claims abstract description 18
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 18
- 230000009467 reduction Effects 0.000 claims abstract description 12
- 238000010521 absorption reaction Methods 0.000 claims description 50
- 239000000284 extract Substances 0.000 claims description 10
- 230000005540 biological transmission Effects 0.000 claims description 3
- 230000014509 gene expression Effects 0.000 claims description 3
- 238000003860 storage Methods 0.000 claims description 3
- 238000004566 IR spectroscopy Methods 0.000 claims 4
- 238000005259 measurement Methods 0.000 abstract description 11
- 230000001360 synchronised effect Effects 0.000 abstract description 5
- 239000007789 gas Substances 0.000 description 121
- 230000003595 spectral effect Effects 0.000 description 8
- 238000001228 spectrum Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
- 238000012544 monitoring process Methods 0.000 description 7
- 238000005070 sampling Methods 0.000 description 7
- 238000000041 tunable diode laser absorption spectroscopy Methods 0.000 description 6
- 238000002329 infrared spectrum Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 229910002091 carbon monoxide Inorganic materials 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- 239000013307 optical fiber Substances 0.000 description 3
- 238000012795 verification Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000004451 qualitative analysis Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 230000004043 responsiveness Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Images
Landscapes
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The utility model discloses a multichannel gas concentration detection system based on mid-infrared absorption spectrum, the detection system mainly comprises a laser temperature control module, a laser current control module, a mid-infrared laser, a beam splitter module, a plane reflector module, an optical switch module, a gas cell module, a concave mirror module, a photoelectric detector, a phase reduction amplification module, a data acquisition module and a data processing and display module; the middle infrared laser emits laser, a plurality of measuring light paths capable of controlling on-off are formed under the matching of the beam splitter module and the optical switch module, the gas concentration of the gas cell module is detected, the generated multi-path concentration signals are sequentially detected and received by the photoelectric detector, are collected by the data acquisition module, and are sent to the data processing and display module to calculate the concentration values of the multi-path gas to be detected, so that the concentration distribution results of a plurality of points to be detected are obtained. The utility model discloses a gas concentration synchronous detection to a plurality of measurement stations, a plurality of passageway.
Description
Technical Field
The utility model relates to an optical detection field, in particular to multichannel gas concentration detecting system based on mid-infrared absorption spectrum.
Background
The optical detection technology has the characteristics of high sensitivity, low detection limit and fast response, is becoming the mainstream method for detecting the concentration of the trace gas, and is widely applied to the fields of combustion diagnosis, industrial process control, atmosphere trace detection, medical research and the like. The TDLAS is a high-resolution optical measurement technology, and scans a single characteristic absorption spectral line of a measured gas by using the narrow line width and wavelength tuning characteristics of a laser to obtain infrared spectrum characteristic information of a target gas, so that various parameters of the gas, such as concentration, temperature and the like, are calculated in an inversion manner, and qualitative and quantitative analysis of the gas is realized. The spectral distribution of various gases can be divided into near infrared spectrum and mid infrared spectrum, wherein most substances have strong characteristic absorption spectral lines in the mid infrared spectrum region, and are several orders of magnitude larger than the near infrared band, which is very beneficial to the measurement of the spectrum and is becoming a hot direction for scientific research and industrial application.
In the actual industrial process control and safety monitoring process, the space size of the monitored object is often large, and the single-point detection and multi-point mixed detection result of the gas concentration is difficult to comprehensively represent the planar distribution state of the gas concentration in the whole monitored object, so that the improvement of the industrial process control and safety monitoring level is greatly limited. However, due to the limitation of cost, it is difficult to install an optical sensing system at each measuring point, especially a middle infrared TDLAS system with high cost. At present, the present one set of mid-infrared TDLAS system component includes: the device comprises a mid-infrared laser, a plurality of plane reflectors, a concave mirror, a gas absorption cell, a photoelectric detector, a phase-locked amplification module and a collection and display module. Because only one laser generates one outgoing laser, only one measuring channel can be formed to measure the gas concentration at one point. Since the mid-infrared laser is expensive, although a plurality of beams of measuring laser can be generated by using a plurality of mid-infrared lasers, the cost of the system is high, and the complexity and maintenance cost of the system are greatly increased. Meanwhile, the mid-infrared optical fiber is not applied to large-scale commercialization, so that the emergent laser beam splitting of a single mid-infrared laser cannot be realized by the optical fiber, and the development of a mid-infrared multichannel gas concentration synchronous detection technology is further limited. Therefore, a high-precision multi-channel gas concentration synchronous detection technology and system are urgently needed for the fields such as industrial process control and safety monitoring. At present, the present one set of mid-infrared TDLAS system component includes: the device comprises a mid-infrared laser, a plurality of plane reflectors, a concave mirror, a gas absorption cell, a photoelectric detector, a phase-locked amplification module and a collection and display module. The main working process is as follows: a mid-infrared laser generates a beam of emergent laser, the emergent laser is reflected into the gas cell through the plane mirror, and after the emergent laser interacts with the gas to be measured, the emergent laser is reflected by the combination of the plane mirror and the concave mirror and is converged on the photoelectric detector. The detected optical signal is converted into an electric signal, demodulated by a phase-locked amplifier, and calculated and displayed by a collecting and displaying module. Because only one laser generates one outgoing laser, only one measuring channel can be formed to measure the gas concentration at one point. The existing set of mid-infrared TDLAS system only has one measuring channel and cannot realize the gas concentration measurement of multiple channels and multiple channels.
The forest health utility model discloses a portable near-infrared multichannel spectrum appearance, this utility model includes mainly that the casing, the probe possess a plurality of conduction optic fibre. The shell mainly comprises a plurality of groups of focusing lenses, a slit die, a light splitting system, a photoelectric detector and a data processing unit. The utility model belongs to the near infrared spectrum field, which realizes the light splitting of the laser by the optical fiber, thereby realizing the multi-channel measurement (forest comfort. a portable near infrared multi-channel spectrometer, utility model patent, CN206696177U, granted announcement date: 2017.12.01).
The utility model discloses automatic verification system of multi-channel carbon monoxide detection alarm in the morning such as Zhao shangyu. Each channel is provided with a carbon monoxide alarm, and standard gas is automatically distributed to each channel, so that the automatic verification of the alarm is realized (Zhao Shangyu, Chen Ke Wu, Chen Mei, multichannel carbon monoxide detection alarm automatic verification system, CN109917076U, application publication No. 2019.06.21).
The utility model discloses a sampling multichannel SF of bleeding6Quantitative leakage alarm system. The system is mainly characterized in that different sampling points are arranged, target gases at different sampling points are fed into a multi-channel sampling chamber through control of corresponding electromagnetic valves, then the target gases enter an analyzer, electromagnetic valves at other points are in a closed state and do not exhaust, and therefore SF at a certain point is achieved6Quantitative leakage detection and alarm. The utility model discloses a multichannel SF6The quantitative leakage alarm relates to a multi-channel sampling air chamber, one measuring point can be sampled into the air chamber of a corresponding channel each time under the control of an electromagnetic valve, and then the air chamber is sent into an analysis unit for analysis (Wangxiang, an air extraction sampling type multi-channel SF6 quantitative leakage alarm system, CN208538301U, authorized bulletin date: 2019.02.22).
Utility model such as roman has provided an integrated infrared gas sensor of multichannel. The sensor is mainly characterized in that a plurality of optical grooves and a plurality of air grooves are prepared on a silicon substrate. And an infrared light source window and an infrared sensitive element window are arranged at the head and the tail of each light groove, so that a plurality of measuring channels are formed. The utility model discloses a multichannel measuring form is that a plurality of light sources correspond a plurality of gas chambers (Ravinbo, open flourishing, Yuanbo etc.. A multichannel integrated infrared gas sensor, CN109596560U, authorized announcement day: 2019.04.09).
The donyou optical corporation utility model discloses a gas detection device with a multi-chamber structure for multi-point detection. The device is mainly characterized in that three air chambers are arranged in a triangular shape. A light source is utilized, a focusing lens and a light filter are combined, and a circular plate with the opening diameter being the diameter of the gas cell is placed at the front of the light source to rotate, so that a passage is formed for the fixed gas cell at a certain time period, a measuring channel is formed, and concentration is measured. The multi-point detection mode of the utility model is a mode of utilizing mechanical movement, a measuring channel is formed at each time, and the measurement of an air chamber is completed (Dongyou optical Co., Ltd., utility model discloses a multi-air chamber structure for multi-point detection, CN109959614A, application publication date: 2019.07.02).
SUMMERY OF THE UTILITY MODEL
The utility model aims to solve the mid-infrared TDLAS technique in such as industrial process control and safety monitoring process field application, single-point detection and multiple spot mix the testing result and are difficult to the gaseous concentration plane distribution state problem in the whole jumbo size monitor object of comprehensive sign, a multichannel gas concentration detecting system based on mid-infrared absorption spectrum is provided, effectively realize the gas concentration that one set of detecting system detected a plurality of passageways simultaneously, obtain the gaseous concentration distribution in the jumbo size monitor object, effectively improve industrial process control and safety monitoring process level, reduce gaseous concentration plane distribution and detect required equipment cost and maintenance cost.
The utility model discloses at least, one of following technical scheme realizes.
The detection system comprises a laser temperature control module, a laser current control module, a mid-infrared laser, a beam splitter module, a plane mirror module, an optical switch module, a gas cell module, a concave mirror module, a photoelectric detector, a phase reduction amplification module, a data acquisition module and a data processing and display module;
the laser temperature control module, the laser current control module and the optical switch module are respectively connected with the data processing and displaying module, and the data processing and displaying module is used for setting the temperature and current parameters of the laser temperature control module and the laser current control module and the on-off time and sequence of the optical switch module; the laser temperature control module and the laser current control module are both connected with the intermediate infrared laser to generate a temperature control signal and a current drive scanning and modulating signal of the intermediate infrared laser; the emitted laser generated by the intermediate infrared laser is split by a beam splitter module, the split laser is injected into a corresponding gas cell module under the on-off control of an optical switch module, the laser transmitted from the gas cell module is converged to a photoelectric detector through a plane mirror module and a concave mirror module, and is amplified by a pre-amplification circuit arranged in the photoelectric detector, and then is sent to a phase reduction amplification module to demodulate, reduce noise and extract secondary harmonic signals of each path of amplified concentration electric signals; the data acquisition module acquires each path of second harmonic signal, sends the signal into the data processing and display module, and finally completes the inversion, display and storage of each path of gas concentration in the data processing and display module.
Further, the beam splitter module comprises a first beam splitter and a second beam splitter;
the optical switch module comprises a first optical switch, a second optical switch and a third optical switch;
the first beam splitter and the second beam splitter divide the emitted laser into three beams, and the three beams of split laser are respectively incident to the first optical switch, the second optical switch and the third optical switch by combining with the first plane mirror of the plane mirror module.
Further, the first optical switch, the second optical switch and the third optical switch enable laser to pass through only during the period that the shutters are opened through opening and closing of the shutters, so that on-off control of an optical path is completed, and the opening time of the shutters is shorter than 10 ms.
Furthermore, only one intermediate infrared laser is utilized, and the beam splitter module, the optical switch module and the gas cell module are matched for use, so that a plurality of measuring light paths are formed, and the gas concentration detection of a plurality of channels and a plurality of measuring points can be carried out.
Further, the gas cell module comprises a first gas absorption cell, a second gas absorption cell and a third gas absorption cell;
the plane reflector module comprises a first plane reflector, a second plane reflector and a third plane reflector;
the concave mirror module comprises a first concave mirror, a second concave mirror and a third concave mirror;
the multi-path laser transmitted from the gas cell module is reflected by the plane mirror module and the concave mirror module and converged on a photoelectric detector.
Furthermore, the photoelectric detector sequentially detects and receives the multiple paths of transmission laser transmitted from the first gas absorption cell, the second gas absorption cell and the third gas absorption cell according to the set on-off sequence and time of the optical switch.
Furthermore, the phase reduction amplification module demodulates, reduces noise and extracts second harmonic signals from each path of concentration electric signals received in sequence, the signals are acquired by the data acquisition module and are sent to the data processing and display module, the data processing and display module respectively extracts the peak values of each path of second harmonic signals and performs least square fitting on the peak values and the corresponding configuration concentrations to obtain the relational expression of the peak values and the concentrations of each path of second harmonic signals, so as to establish respective concentration inversion models; when each path of gas absorption tank is introduced into the gas with unknown concentration at the plane distribution measuring point in the object to be measured, the concentration value of each path of gas is calculated and inverted according to the generated second harmonic signal and the established concentration inversion model, the plane distribution result of the concentration of the gas to be measured in the object to be measured is obtained, and the plane distribution result is displayed and stored in a data table or cloud picture mode.
Furthermore, the relation between the peak value and the concentration of the second harmonic signal of each path is YnConcentration of=AnXPeak value of signal+ Bn, wherein YnConcentration ofThe measured gas concentration of the nth channel is defined as An, the channel coefficient of the nth channel is defined as An, and the channel influence factor of the nth channel is defined as Bn.
According to the detection method of the multi-channel gas concentration detection system based on the mid-infrared absorption spectrum, a plurality of measurement channels are formed by utilizing the beam splitting function of the beam splitter, and the on-off control function of the optical switch is utilized to realize the sequential and orderly detection of the plurality of channels, and the method specifically comprises the following steps:
s1, introducing the gas at the measuring point meeting the measuring requirements into a first gas absorption pool, a second gas absorption pool and a third gas absorption pool through pipelines, and then discharging the gas from the exhaust port of each gas pool to ensure that the flow of the fresh gas at the measuring point is always kept in each gas pool during normal work, so that the dynamic change of the gas concentration at each measuring point can be reflected in real time;
s2, setting relevant parameters of a laser temperature control module and a laser current control module by a data processing and displaying module, generating a temperature control signal and a current driving scanning signal of a mid-infrared laser, enabling the variation range of the scanning wavelength of the mid-infrared laser to cover the characteristic spectrum absorption line of a target gas in a mid-infrared region while ensuring that the mid-infrared laser generates emission laser, simultaneously starting an optical switch, and setting the on-off time and the sequence of a first optical switch, a second optical switch and a third optical switch by the data processing and displaying module;
s3, splitting the emitted laser by the first beam splitter and the second beam splitter according to a set splitting ratio, controlling the split laser by the optical switch module by combining with the first plane mirror of the plane mirror module, sequentially controlling the split laser to enter the first gas absorption cell, the second gas absorption cell and the third gas absorption cell according to a set on-off sequence and time, and absorbing the incident laser by the gas to be detected, so that the laser intensity is weakened, the transmitted laser is obtained, and the spectral signal absorbed by the gas to be detected is generated;
s4, converging the multi-path spectrum signals to a photoelectric detector through the laser containing the spectrum information transmitted by the first gas absorption cell, the second gas absorption cell and the third gas absorption cell by the second plane reflecting mirror, the third plane reflecting mirror, the first concave mirror, the second concave mirror and the third concave mirror;
s5, under the control of the sequential on-off of the optical switch, the photoelectric detector sequentially detects and receives a plurality of paths of optical signals containing the concentration information of the gas to be detected, converts the optical signals into electric signals, and amplifies the electric signals through a built-in preamplification circuit;
s6, the phase reduction amplification module demodulates, reduces noise and extracts second harmonic signals of each path of amplified concentration electric signals; the data acquisition module acquires the second harmonic signals and sends the signals to the data processing and displaying module, the data processing and displaying module automatically judges the concentration signals corresponding to each measuring channel according to the set on-off sequence and the time before and after the signals are obtained, and the concentration of the gas to be measured of the measuring point corresponding to the channel is obtained through calculation by the concentration inversion model of the channel, so that the planar distribution result of the concentration of the gas to be measured in the object to be measured is obtained, and the planar distribution result of the concentration of the gas to be measured in the object to be measured is displayed and stored in a data table or cloud picture mode.
Compared with the prior art, the beneficial effects of the utility model are that:
the utility model provides a gaseous detecting system of multichannel based on mid-infrared absorption spectrum can realize the gas concentration plane distribution state in the accurate detection jumbo size monitoring object of high sensitivity, low detection limit, quick responsiveness. The system only utilizes a single intermediate infrared laser and a single photoelectric detector, and can realize that detection signals of gas at each measuring point sequentially occur according to a set on-off sequence of the optical switch through the matching use of the beam splitter and the optical switch, the data acquisition and processing are sequentially carried out according to the set sequence, the detection time of all channels of the whole system is not more than 1s, and the equipment cost and the maintenance cost are obviously reduced while the synchronous detection of multi-channel and multi-channel gas is effectively realized.
Drawings
Fig. 1 is a schematic structural diagram of a multi-channel gas concentration detection system based on mid-infrared absorption spectrum according to this embodiment.
Detailed Description
The technical solution in the embodiment of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiment of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. Based on the embodiments of the present invention, all other embodiments obtained by a person having ordinary skill in the art without inventive skill belong to the protection scope of the present invention.
The multi-channel gas concentration detection system based on the mid-infrared absorption spectrum shown in fig. 1 mainly includes a laser temperature control module 1, a laser current control module 2, a mid-infrared laser 3, a first beam splitter 401, a second beam splitter 402, a first plane mirror 501, a second plane mirror 502, a third plane mirror 503, a first optical switch 601, a second optical switch 602, a third optical switch 603, a first gas absorption cell 701, a second gas absorption cell 702, a third gas absorption cell 703, a first concave mirror 801, a second concave mirror 802, a third concave mirror 803, a photodetector 9, a phase reduction amplification module 10, a data acquisition module 11, and a data processing and display module 12.
The models of the phase reduction amplification module 1 and the data acquisition module 11 used in the embodiment are HP-DLIA-5 and NI-6330, respectively, and the models of the data processing and display module 12 are AIMB-501 and SK19GA, respectively.
The laser temperature control module 1 and the laser current control module 2 are respectively connected with the data processing and display module 12, and the data processing and display module 12 is used for setting the temperature and current parameters of the laser temperature control module 1 and the laser current control module 2 and setting the on-off time and sequence parameters of the optical switch;
the laser temperature control module 1 and the laser current control module 2 are both connected with the intermediate infrared laser 3 to generate a temperature control signal and a current drive scanning and modulating signal of the intermediate infrared laser 3, so that the variation range of the scanning wavelength of the intermediate infrared laser 3 covers the characteristic spectrum absorption line of the target gas in the intermediate infrared region while the normal work of the intermediate infrared laser is ensured.
The emitted laser generated by the mid-infrared laser 3 is evenly divided into three beams by the first beam splitter 401 and the second beam splitter 402 according to a set splitting ratio, wherein the laser split by the first beam splitter 401 and the second beam splitter 402 is directly led to the first optical switch 601 and the second optical switch 602, the last beam of laser is reflected to the third optical switch 603 by the first plane mirror 501, and the three beams of laser are controlled by the first optical switch 601, the second optical switch 602 and the third optical switch 603 to be incident into the corresponding first gas absorption cell 701, the second gas absorption cell 702 and the third gas absorption cell 703, so as to form three measurement channels in a combined manner. The optical switch sequentially controls three paths of laser to enter each gas absorption cell according to the set on-off sequence and time, and the gas to be detected absorbs the incident laser, so that the light intensity of the laser is weakened, the transmission laser is obtained, and the absorption spectrum signal of the path of gas to be detected is generated.
The laser light containing spectral information transmitted by each gas absorption cell is reflected by the second plane mirror 502 and the third plane mirror 503, and each spectral signal is converged to one photodetector 9 by the first concave mirror 801, the second concave mirror 802, and the third concave mirror 803.
Under the sequential on-off control of the optical switch, the photoelectric detector 9 sequentially detects and receives 3 paths of optical signals containing the concentration information of the gas to be detected, converts the optical signals into electric signals, amplifies the electric signals by a pre-amplification circuit arranged in the photoelectric detector 9, and sends the electric signals into the phase reduction amplification module 10 to demodulate, reduce noise and extract second harmonic signals of the three paths of amplified concentration electric signals; the data acquisition module 11 acquires the three secondary harmonic signals and sends the signals to the data processing and display module 12. Finally, the inversion, display, storage and the like of the concentration of each path are completed in the data processing and display module 12.
The detection method of the multi-channel gas concentration detection system based on the mid-infrared absorption spectrum comprises the following steps:
s1, in an industrial process or safety monitoring, three gridding or matrixing measuring points are arranged in the space of the object to be measured needing to detect the planar distribution of the gas concentration. The method comprises the steps of taking out gas of 3 arrangement measuring points in a space of an object to be measured in a sampling mode, after dedusting and condensation, introducing clean gas to be measured of the three measuring points at normal temperature and normal pressure into a first gas absorption pool 701, a second gas absorption pool 702 and a third gas absorption pool 703 of a system at a certain flow rate according to measurement requirements, and then discharging the gas from exhaust ports of the gas pools to ensure that fresh gas of the measuring points to be measured always flows in the gas pools of the system during normal work, so that the gas concentration dynamic change of the measuring points can be reflected in real time.
S2, the data processing and display module 12 sets the relevant parameters of the laser temperature control module 1 and the laser current control module 2, generates the temperature control signal and the current drive scanning signal of the mid-infrared laser 3, and ensures that the variation range of the scanning wavelength of the mid-infrared laser 3 covers the characteristic spectrum absorption line of the target gas in the mid-infrared region while ensuring the normal work of the mid-infrared laser. The mid-infrared laser 3 generates emission laser light. In addition, the optical switches are activated, and the on-off time and the on-off sequence of the first optical switch 601, the second optical switch 602, and the third optical switch 603 are set by the data processing and display module 12.
S3, the emitted laser generated by the mid-infrared laser 3 is divided into three beams by the first beam splitter 401 and the second beam splitter 402 according to a fixed splitting ratio, and the divided laser is controlled by the first optical switch 601, the second optical switch 602, and the third optical switch 603 to be incident into the corresponding first gas absorption cell 701, the second gas absorption cell 702, and the third gas absorption cell 703, so as to form three measurement channels in combination. The optical switch sequentially controls three paths of laser to enter each gas absorption cell according to a set on-off sequence and time, and the gas to be detected absorbs incident laser, so that the light intensity of the laser is weakened, transmitted laser is obtained, and a spectrum signal absorbed by the path of gas to be detected is generated;
s4, the laser beam containing the spectral information transmitted by each gas absorption cell is reflected by the second plane mirror 502 and the third plane mirror 503, and then each spectral signal is converged on one photodetector 9 by the first concave mirror 801, the second concave mirror 802, and the third concave mirror 803.
S5, the photoelectric detector 9 detects and receives 3 paths of optical signals containing the concentration information of the gas to be detected, which are transmitted from the first gas absorption cell 701, the second gas absorption cell 702 and the third gas absorption cell 703 in sequence according to the set on-off sequence and time of the optical switch, converts the optical signals into electric signals, and then amplifies the electric signals through a built-in pre-amplification circuit;
s6, the phase reduction amplification module 10 demodulates, reduces noise and extracts harmonic signals from the three paths of amplified concentration electric signals; the data acquisition module 11 acquires the three harmonic signals and sends the signals to the data processing and display module 12. The data processing and display module 12 extracts the second harmonic signal peaks of the three paths respectively, and performs least square fitting on the second harmonic signal peaks and the corresponding configuration concentrations to obtain a relational expression between the harmonic signal peaks and the concentrations of the respective paths, which is generally YnConcentration of=AnXPeak value of signal+ Bn (where, YnConcentration ofAnd the concentration of the gas to be detected in the nth channel is determined, An is the channel coefficient of the nth channel, and Bn is the channel influence factor of the nth channel), so that respective concentration inversion models are established. When each path of gas absorption tank is introduced into the gas with unknown concentration at the plane distribution measuring point in the object to be measured, the concentration value of each path of gas can be inverted by combining the established concentration inversion model according to the generated second harmonic signal to obtain the plane distribution result of the concentration of the gas to be measured in the object to be measured, and the plane distribution result is displayed and stored in a data table or cloud picture mode.
The total time of the measurement of the concentration of the three paths of gases, the demodulation and extraction of signals, the data acquisition, the concentration inversion and the display is not more than 1 s.
The number of the measuring channels formed by combining the laser beam splitting and the plurality of gas pools is not limited to three, and can be a plurality, so that the synchronous detection of the multi-channel and multi-path gas concentration is completed.
The above description is only for the purpose of describing one embodiment of the present invention, and should not be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, many variations and modifications can be made without departing from the spirit of the invention, and these are all within the scope of the invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (8)
1. The multi-channel gas concentration detection system based on the mid-infrared absorption spectrum is characterized by comprising a laser temperature control module (1), a laser current control module (2), a mid-infrared laser (3), a beam splitter module, a plane mirror module, an optical switch module, a gas cell module, a concave mirror module, a photoelectric detector (9), a phase reduction amplification module (10), a data acquisition module (11) and a data processing and display module (12);
the laser temperature control module (1), the laser current control module (2) and the optical switch module are respectively connected with the data processing and displaying module (12), and the data processing and displaying module (12) is used for setting the temperature and current parameters of the laser temperature control module (1) and the laser current control module (2) and the on-off time and sequence of the optical switch module; the laser temperature control module (1) and the laser current control module (2) are both connected with the intermediate infrared laser (3) to generate a temperature control signal and a current drive scanning and modulating signal of the intermediate infrared laser (3); the emitted laser generated by the intermediate infrared laser (3) is split by a beam splitter module, the split laser is injected into a corresponding gas cell module under the on-off control of an optical switch module, the laser transmitted from the gas cell module is converged to a photoelectric detector (9) through a plane mirror module and a concave mirror module, and is amplified by a pre-amplification circuit arranged in the photoelectric detector (9), and then is sent to a phase reduction amplification module (10) to demodulate, reduce noise and extract secondary harmonic signals of each amplified concentration electric signal; the data acquisition module (11) acquires each path of second harmonic signal, sends the signal into the data processing and display module (12), and finally completes the inversion, display and storage of each path of gas concentration in the data processing and display module (12).
2. The mid-infrared absorption spectroscopy-based multi-channel gas concentration detection system according to claim 1, wherein the beam splitter module comprises a first beam splitter (401) and a second beam splitter (402);
the optical switch module comprises a first optical switch (601), a second optical switch (602) and a third optical switch (603);
the first beam splitter (401) and the second beam splitter (402) divide the emitted laser into three beams, and the three beams of split laser are respectively incident to the first optical switch (601), the second optical switch (602) and the third optical switch (603) by combining with the first plane mirror (501) of the plane mirror module.
3. The system for detecting the concentration of a multi-channel gas based on the mid-infrared absorption spectrum is characterized in that the first optical switch (601), the second optical switch (602) and the third optical switch (603) enable laser to pass through only during the opening period of the shutters thereof through the opening and closing of the shutters thereof, so that the on-off control of the optical path is completed, and the opening time of the shutters thereof is less than 10 ms.
4. The mid-infrared absorption spectroscopy-based multi-channel gas concentration detection system according to claim 3,
and only one intermediate infrared laser (3) is utilized, and a plurality of measuring light paths are formed by matching and using the beam splitter module, the optical switch module and the gas cell module, so that the gas concentration detection of a plurality of channels and a plurality of measuring points can be carried out.
5. The mid-infrared absorption spectroscopy-based multi-channel gas concentration detection system according to claim 4,
the gas cell module comprises a first gas absorption cell (701), a second gas absorption cell (702) and a third gas absorption cell (703);
the plane mirror module comprises a first plane mirror (501), a second plane mirror (502) and a third plane mirror (503);
the concave mirror module comprises a first concave mirror (801), a second concave mirror (802) and a third concave mirror (803);
the multi-path laser transmitted from the gas cell module is reflected by the plane mirror module and the concave mirror module and converged on a photoelectric detector (9).
6. The mid-infrared absorption spectroscopy-based multi-channel gas concentration detection system according to claim 5,
the photoelectric detector (9) sequentially detects and receives multiple paths of transmission laser transmitted from the first gas absorption cell (701), the second gas absorption cell (702) and the third gas absorption cell (703) according to the set on-off sequence and time of the optical switch.
7. The system for detecting the concentration of the multi-channel gas based on the mid-infrared absorption spectrum according to claim 6, wherein the phase reduction amplification module (10) demodulates, reduces noise and extracts second harmonic signals from each channel of concentration electric signals received in sequence, the signals are acquired by the data acquisition module (11) and sent to the data processing and display module (12), the data processing and display module (12) respectively extracts the peak values of each channel of second harmonic signals and performs least square fitting on the peak values and the corresponding configured concentrations to obtain the relational expressions between the peak values and the concentrations of each channel of second harmonic signals, so as to establish respective concentration inversion models; when each path of gas absorption tank is introduced into the gas with unknown concentration at the plane distribution measuring point in the object to be measured, the concentration value of each path of gas is calculated and inverted according to the generated second harmonic signal and the established concentration inversion model, the plane distribution result of the concentration of the gas to be measured in the object to be measured is obtained, and the plane distribution result is displayed and stored in a data table or cloud picture mode.
8. The mid-infrared absorption spectrum-based multi-channel gas concentration detection system according to claim 7, wherein the relation between the peak value and the concentration of the second harmonic signal of each channel is YnConcentration of=AnXPeak value of signal+ Bn, wherein YnConcentration ofThe measured gas concentration of the nth channel is defined as An, the channel coefficient of the nth channel is defined as An, and the channel influence factor of the nth channel is defined as Bn.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021256139.XU CN212722599U (en) | 2020-06-30 | 2020-06-30 | Multi-channel gas concentration detection system based on mid-infrared absorption spectrum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021256139.XU CN212722599U (en) | 2020-06-30 | 2020-06-30 | Multi-channel gas concentration detection system based on mid-infrared absorption spectrum |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN212722599U true CN212722599U (en) | 2021-03-16 |
Family
ID=74962407
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202021256139.XU Withdrawn - After Issue CN212722599U (en) | 2020-06-30 | 2020-06-30 | Multi-channel gas concentration detection system based on mid-infrared absorption spectrum |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN212722599U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707634A (en) * | 2020-06-30 | 2020-09-25 | 华南理工大学 | Multi-channel gas concentration detection system and method based on mid-infrared absorption spectrum |
-
2020
- 2020-06-30 CN CN202021256139.XU patent/CN212722599U/en not_active Withdrawn - After Issue
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111707634A (en) * | 2020-06-30 | 2020-09-25 | 华南理工大学 | Multi-channel gas concentration detection system and method based on mid-infrared absorption spectrum |
| CN111707634B (en) * | 2020-06-30 | 2024-04-19 | 华南理工大学 | Multichannel gas concentration detection system and method based on mid-infrared absorption spectrum |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111707634B (en) | Multichannel gas concentration detection system and method based on mid-infrared absorption spectrum | |
| US11397149B2 (en) | Laser radar system apparatus for multi-wavelength measurement of atmospheric carbon dioxide concentration and vertical aerosol profile | |
| CN104280362B (en) | A kind of superheated vapor laser spectrum on-line detecting system | |
| CN106802288B (en) | Gas-detecting device and method based on tunable laser and super continuous spectrums laser | |
| US3696247A (en) | Vehicle exhaust emissions analyzer | |
| CA2458123C (en) | Remote sensing of gas leaks | |
| CN104596987A (en) | Mid-infrared spectroscopy-based trace gas detection method and device combining long-optical-path open light path with wavelength modulation technique | |
| CN111122496A (en) | Calibration-free gas concentration measuring device and method | |
| CN102253012B (en) | Device and method for measuring extinction coefficient of black carbon aerosol | |
| CN103134771A (en) | Carbon monoxide (CO) concentration and visibility detector and detection method thereof | |
| CN110320178A (en) | A kind of gas detecting system and its detection method based on wavelength modulation spectrum technology | |
| US3897155A (en) | Atomic fluorescence spectrometer | |
| CN108801977A (en) | Without calibration trace amounts of carbon 12 and 13 carbon dioxide gas detection device of carbon and method | |
| CN212722599U (en) | Multi-channel gas concentration detection system based on mid-infrared absorption spectrum | |
| US4803052A (en) | Carbon monoxide detector | |
| CN201210140Y (en) | Multi-parameter laser wavelength modulation spectrum detection apparatus used in fire field | |
| CN202177572U (en) | Spectral measuring system for multi-component gas | |
| CN203414408U (en) | Laser-induced breakdown spectroscopy analysis system | |
| CN203275292U (en) | Instrument for detecting concentration and visibility of CO (Carbonic Oxide) | |
| EP0105659A2 (en) | Carbon monoxide detectors | |
| CN209606313U (en) | The device of sulfur dioxide and nitrogen dioxide in surrounding air is detected simultaneously | |
| CN210108948U (en) | Optical integrating sphere and gas sample terahertz spectrum acquisition device | |
| CN208283270U (en) | Natural gas leaking early warning monitoring device based on optical fiber FP lumen type probe | |
| CN116380838B (en) | Greenhouse gas measurement system and method based on multipath infrared laser absorption spectrum | |
| Chang et al. | Detection of O18 and D Isotopes in Water Vapor using a Fiber-Coupled Tunable Diode Laser Absorption Spectroscopy Multi-Pass Cell |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| AV01 | Patent right actively abandoned |
Granted publication date: 20210316 Effective date of abandoning: 20240419 |
|
| AV01 | Patent right actively abandoned |
Granted publication date: 20210316 Effective date of abandoning: 20240419 |
|
| AV01 | Patent right actively abandoned | ||
| AV01 | Patent right actively abandoned |