CN110501306A - A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration - Google Patents
A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration Download PDFInfo
- Publication number
- CN110501306A CN110501306A CN201910916185.3A CN201910916185A CN110501306A CN 110501306 A CN110501306 A CN 110501306A CN 201910916185 A CN201910916185 A CN 201910916185A CN 110501306 A CN110501306 A CN 110501306A
- Authority
- CN
- China
- Prior art keywords
- laser
- diesel engine
- highly sensitive
- hollow
- core fiber
- 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.)
- Pending
Links
Classifications
-
- 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
- G01N21/39—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using tunable lasers
Landscapes
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Analytical Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Optics & Photonics (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The present invention relates to a kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration field, the measuring device include: laser, reference gas pond, hollow-core fiber, optical window mirror, compressed air interface, Diesel Engine Exhaust Pipe, plus lens, laser detector, data processing module, the reference gas pond are connected on the optical window mirror by the hollow-core fiber, the optical window mirror and the plus lens are symmetrically distributed in the two sides of the Diesel Engine Exhaust Pipe, and the plus lens is connected by the hollow-core fiber with the laser detector.The present invention can save reference channel by being inserted into reference gas pond to simplied system structure, diesel engine is in the process of running, the low-frequency noise of script mechanical noise and instrument is more, it is easy to have an impact measurement, it can effectively improve the signal-to-noise ratio of device by reference to the addition in gas pond, improve measurement sensitivity and precision.
Description
Technical field
The present invention relates to laser measuring device for measuring field more particularly to a kind of highly sensitive diesel engines based on TDLAS technology
Discharge NO2Apparatus for measuring concentration field.
Background technique
Getting worse for Global Environmental Problems, each state all attach great importance to the protection for environment.In China's environmental problem
Also have become and restrict social development, influence the problem of national economy, in terms of atmosphere pollution, the discharge one of Ship Power Equipment
It is directly a major issue.There are further requirement and restriction in Department of Transportation also in the discharge of Pollution From Ships object, this
Corresponding test method device etc. is put forward new requirements, conventional test methodologies have been difficult to meet new requirement.Exist later
The test method that ship row's diesel engine puts pollutant necessarily develops to higher precision, higher response characteristic direction, also can more fill
The real-time online measuring of weight boat diesel engine in actual operation.
TDLAS technology is rapidly developed in recent years, by using TDLAS technology, can complete tens kinds of gases point
Highly selective, the highly sensitive On-line sampling system of son realizes the ginseng such as different field gas concentration, temperature, flow velocity, pressure
Several detected with high accuracy.TDLAS technology has the advantages that following significant: (1) being not necessarily to sampling processing, real-time online measuring；
(2) non-contact measurement can be applied to the on-line measurement under this bad working environments of boat diesel engine；(3) according under test gas
Corresponding absorption peak is chosen, interference of other gases to measurement is avoided.TDLAS technology starts from middle 1960s, adjoint
The development of the technology, the above-mentioned advantage of TDLAS technology is also more prominent, so the extensive concern by researcher.Anhui
TDLAS detection correlative study work is carried out the 1990s where ray machine, then the TDLAS detection system of its exploitation is big
Gas detection and industrial circle are applied.The clean energy of energy project institute, Zhejiang University will using National Key Laboratory
TDLAS technology is studied applied to combustion diagnosis, achieves ideal research achievement.Harbin Engineering University's power and the energy
The Yang Xiaotao of engineering college takes the lead in proposing for TDLAS technology to be applied in boat diesel engine emission test, and has carried out correlation and ground
Study carefully and test, achieves certain achievement.
Tunable diode laser absorption spectrometry technology, as signal source, utilizes the adjustable of laser output using tunable laser source
Humorous characteristic makes a certain specific absorption spectral line of laser output wavelength covering measured matter, according to lambert Bill (Beer-
Lambert) absorption law obtains the concentration information of measured matter.The technology is tunable by output characteristics, avoids tradition
The problem of spectral absorption technology is by output intensity influence of fluctuations, improves measuring accuracy.It is used in tunable laser spectroscopy technology
Be narrow linewidth output laser, for the absorption line of measured matter, by electric current tuning device, realize and composed in specific absorption
The a small range all standing of line, it is possible to prevente effectively from the interference of other material absorbing spectral lines, a large amount of existing especially in burning
Interfering with each other between H2O and CO2 component.But in actual measurement it is not difficult to find that the diesel emission based on TDLAS technology is surveyed
It more significantly include: that (1) boat diesel engine can generate no small vibration in actual moving process there is also some problems in examination
Dynamic, this just proposes certain requirement to the vibration resistance of test equipment；(2) measuring principle based on direct absorption process is relatively easy,
But its measurement result is affected by low-frequency noise, and precision is caused to be subject to certain restrictions；It (3) can be with according to Resonance measuring method
The influence of low-frequency noise is reduced, but also makes apparatus structure and principle more complicated simultaneously, is not easy to carry out experiment on a diesel engine.
Therefore, although TDLAS technology itself, which is, many remarkable advantages, if its practical applies in diesel emission test is gone back
Further to improve experimental provision, optimization experimentation etc., as far as possible raising measurement accuracy.
Summary of the invention
The object of the present invention is to provide a kind of highly sensitive diesel emission NO based on TDLAS technology2Measurement of concetration dress
It sets, is realized using TDLAS technology to diesel emission NO2The high-sensitivity measurement of concentration.
The present invention is implemented as follows:
A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration, comprising: laser 1, ginseng
Examine gas pond 2, hollow-core fiber 3, optical window mirror 4, compressed air interface 5, Diesel Engine Exhaust Pipe 6, plus lens 7, laser detector
8, data processing module 9, the reference gas pond 2 is connected on the optical window mirror 4 by the hollow-core fiber 3, the optics
Window mirror 4 and the plus lens 7 are symmetrically distributed in the two sides of the Diesel Engine Exhaust Pipe 6, and the plus lens 7 passes through the sky
Core fibre 3 is connected with the laser detector 8.
Polytetrafluoroethylene (PTFE) high temperature dwell sheath is equipped with outside the hollow-core fiber 3.
The laser 1 is tunable laser.
The optical window mirror 4 and the coupling part of the Diesel Engine Exhaust Pipe 6 are equipped at least two compressed air interface 5.
The compressed air interface 5 is arranged symmetrically on interconnecting piece.
The beneficial effects of the present invention are: (1) can save reference channel by being inserted into reference gas pond to simplify system knot
Structure；(2) it is convenient for looking for the position of determining gas absorption peak；(3) NO of the known concentration in reference gas pond2Gas can be also used for
The output of calibration instrument；(4) in the process of running, the low-frequency noise of script mechanical noise and instrument is more for diesel engine, and easy pair
Measurement has an impact, and can effectively improve the signal-to-noise ratio of device by reference to the addition in gas pond, improves measurement sensitivity and precision.
Detailed description of the invention
Fig. 1 is the highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration schematic diagram.
Specific embodiment
Detailed description of the invention: 1 laser, 2 reference gas ponds, 3 hollow-core fibers, 4 optical window mirrors, 5 compressed air interfaces, 6 diesel engines
Exhaust pipe, 7 plus lens, 8 laser detectors, 9 data processing modules.
Present invention is further described in detail with reference to the accompanying drawing.
The invention belongs to laser testing fields, are a kind of variation feelings that light intensity before and after Diesel Engine Exhaust Pipe is passed through according to laser
Condition, and then the method for obtaining exhaust temperature or gas component concentrations.
The innovation of the invention consists in that: by the way that a gas absorption cell is added in experimental provision system, measured in experiment
Before, the NO of known concentration is filled in the gas absorption cell2Gas, due to NO in diesel exhaust gases component itself2Gas
Concentration is relatively low, therefore can effectively enhance the absorption peak identification capability under low concentration by the reference gas pond, to improve dioxy
Change the signal-to-noise ratio of nitrogen concentration measuring signal.In addition to this, laser passes sequentially through reference gas pond and Measurement channel design scheme and double
Channel (Measurement channel with reference channel) parallel scheme, which is compared, has the advantage that (1) can be saved by being inserted into reference gas pond
Go reference channel to simplied system structure；(2) it is convenient for looking for the position of determining gas absorption peak；(3) in reference gas pond
Know the NO of concentration2Gas can be also used for the output of calibration instrument；(4) diesel engine in the process of running, script mechanical noise with
The low-frequency noise of instrument is more, is easy to have an impact measurement, can effectively improve the letter of device by reference to the addition in gas pond
It makes an uproar and compares, improve measurement sensitivity and precision.
The object of the present invention is achieved like this: first by adjusting the temperature of semiconductor laser by filters center wave
Near long modulation gas absorption peak, the output wavelength and width of laser then are modulated by adjusting the Injection Current of laser
Value.Under frequency sweep mode, laser modulation signal is that a low frequency triangular wave (Hz) is superimposed a high_frequency sine wave (kHz).It is low
The effect of frequency triangular wave is the characteristic absorption peak for modulating the inswept gas of central wavelength of laser, to obtain the characteristic light of gas
Spectrum；Sine wave modulation cooperates phase lock amplifying technology, available each harmonic.When laser passes through tested gas, light intensity
Decaying meets lambert-Beer law
It(v)=I0(v)exp[-α(v)PXL]
In formula: I0For the initial beam intensity of laser, ItLight intensity after passing through oil film for laser, T are temperature, and P is tested gas
Stagnation pressure, X are the volumetric concentrations of tested gas, and L is light path, and α (v) is absorption coefficient.It is verified through mathematical derivation, absorption coefficient (v)
The amplitude of each rank Fourier coefficient be all proportional to the concentration of gas and the product of light path.Using wavelength-modulation technique and use one
Subharmonic normalizes second harmonic signal.After laser successively passes through reference gas pond and Diesel Engine Exhaust Pipe, shoot laser quilt
Photodetector receives, subsequent connection data processing module, by calculating the last concentration group for obtaining surveyed nitrogen dioxide gas
Point.
The invention also includes features some in this way:
1. laser used in is tunable laser, changes the wave number that Injection Current is changeable output laser.
2. measurement method is non-contact measurement, and measurement also has the characteristics that highly sensitive, high response characteristic, safety
Reliably.
3. being equipped with compressed air interface with Diesel Engine Exhaust Pipe connected component, carry out compressed air to optical mirror slip
Purging, so as to avoid because of lens contamination caused by light transmittance decline.
4. Diesel Engine Exhaust Pipe is connected with front and back device to be realized by hollow-core fiber, outer fiber all increases polytetrafluoro
Ethylene high temperature dwell sheath, the addition of optical fiber can increase the vibration resistance of whole device to reduce vibration to the shadow of optical path and measurement
It rings, in addition to this, photodetector is increased at a distance from exhaust pipe by optical fiber, avoid Diesel Engine Exhaust Pipe in measurement process
Temperature is excessively high and damages detector.
5. data processing module is integrated with signal generator, laser controller, temperature controller, lock-in amplifier etc., compared with
Effectively to optimize system structure, it is convenient for the adjusting to laser and subsequent signal receives and data processing
Journey.
The present invention is further described below:
A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration, including laser controller,
Laser 1, optical window mirror 4, photodetector, reference gas pond 2, plus lens 7, the structures such as hollow-core fiber 3 utilize TDLAS skill
Art is realized to diesel emission NO2The measurement of concentration.
Laser 1 exports the wavelength locking of laser to NO2The peak position of gas absorption peak avoids the dry of other gases
It disturbs.
Laser is measured directly through Diesel Engine Exhaust Pipe 6, without sampling process, it can be achieved that real-time online measuring.
One is added in optical path full of known concentration NO2Reference gas pond 2, to improve system in low NO2It is dense
Measuring signal signal-to-noise ratio under environment is spent, convenient for determining the position of gas absorption peak in data handling procedure.
By being inserted into reference gas pond 2 in gasmetry optical path, reference channel simplied system structure can be saved, is also convenient for
The output of calibration instrument.
In device with to be connected before and after Diesel Engine Exhaust Pipe 6 be hollow-core fiber 3, can effectively enhance the antivibration of whole device
Property, and photodetector can be made far from Diesel Engine Exhaust Pipe 6, to guarantee that its operating temperature is normal.
The flange fitting being connected with Diesel Engine Exhaust Pipe 6 is circular configuration, and is equipped with special compressed air inlet port,
Purpose is that purging eyeglass prevents its pollution, impacts measurement to block optical path.
As shown in Figure 1, laser projects laser, shoot laser first passes through the NO full of known concentration2Reference gas pond,
Enter optical fiber after coming out from reference gas pond, by passing through Diesel Engine Exhaust Pipe later, the light of outgoing is after plus lens by light
Electric explorer receives, and finally obtains NO by data processing module2Concentration.Data processing module is for adjusting laser, signal
Processing and the output of measurement result.
In the use of the present invention, according to the following steps: (1) first having to adjust optical path, the optical path adjusting of present apparatus system is simultaneously
It is uncomplicated, check that optical path alignment is ready for further work later；(2) quantitative NO is filled with into reference gas pond2Gas, In
In the case where not running diesel engine, laser and photodetector etc. are connected, is measured to rectify an instrument；(3) normal
It opens diesel engine to be tested, to guarantee to continue in the process to inflate from compressed air interface, to guarantee to make the purging of eyeglass
It will not be contaminated, and open laser and photodetector measures.(4) it completes complete by data processing module after measuring
It handles to obtain measurement result at follow-up data, further according to the error correction for being not keyed up the data progress instrument measured, finally obtain
Measurement result after correction.
In measurement process, because of the NO that diesel engine is discharged when working operation2Gas concentration is lower, therefore uses conventional method
It is not easy to capture when measuring and finds absorption peak, and gained measurement accuracy is relatively low.It can be very intuitive using the present invention
Search out NO2The absorption peak of gas, even if NO2Gas is very low to be ignored；In addition to this, it is tested in diesel engine operation
Script mechanical noise and instrument low-frequency noise are just very much, are easy to generate interference to measurement result, through the invention can be effective
The signal-to-noise ratio of device is improved, therefore improves the sensitivity and precision of measurement.Entire measuring system is carried out based on TDLAS technology
What design was realized, therefore it has highly sensitive, high response characteristic, high measurement accuracy and that real-time online may be implemented is non-contact
The advantages of formula measures, therefore it is very suitable for being applied in the emission test of marine diesel.
In conclusion the invention discloses a kind of highly sensitive diesel emission NO based on TDLAS technology2Measurement of concetration
Device, principle are that laser passes through after reference gas pond and Diesel Engine Exhaust Pipe by NO2The absorption of molecule will lead to the variation of light intensity.
The innovation of the invention consists in that reference gas pond, optical fiber, the several designs of compressed air interface.The main function in reference gas pond is can be with
The signal-to-noise ratio of raising system measuring signal under low concentration environment, and convenient for finding the position for determining gas absorption peak, therefore can
To improve the sensitivity of test, measurement accuracy when low concentration test can be also improved.The addition of optical fiber improves entirely in device
The vibration resistance of device reduces the influence due to mechanical oscillation for instrument.The presence of compressed air interface can be filled with compression
Air purges eyeglass, prevents lens contamination, and have certain cooling effect, prevents temperature is excessively high from connecing to eyeglass or optical fiber
Mouth generates damage.After laser successively passes through reference gas pond and exhaust pipe, it is received by a photoelectric detector again by plus lens, most
It is handled eventually by data processing module signal, exports NO2Concentration measurement.
Claims (5)
1. a kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration, comprising: laser (1), reference
Gas pond (2), hollow-core fiber (3), optical window mirror (4), compressed air interface (5), Diesel Engine Exhaust Pipe (6), plus lens (7),
Laser detector (8), data processing module (9), it is characterized in that: the reference gas pond (2) is connected by the hollow-core fiber (3)
In on the optical window mirror (4), the optical window mirror (4) and the plus lens (7) are symmetrically distributed in the diesel exhaust gas
The two sides of (6) are managed, the plus lens (7) is connected by the hollow-core fiber (3) with the laser detector (8).
2. a kind of highly sensitive diesel emission NO based on TDLAS technology according to claim 12Apparatus for measuring concentration,
It is characterized in that: being equipped with polytetrafluoroethylene (PTFE) high temperature dwell sheath outside the hollow-core fiber (3).
3. a kind of highly sensitive diesel emission NO based on TDLAS technology according to claim 12Apparatus for measuring concentration,
It is characterized in that: the laser (1) is tunable laser.
4. a kind of highly sensitive diesel emission NO based on TDLAS technology according to claim 12Apparatus for measuring concentration,
It is characterized in that: the coupling part of the optical window mirror (4) and the Diesel Engine Exhaust Pipe 6 is equipped at least two compressed air interface
(5)。
5. a kind of highly sensitive diesel emission NO based on TDLAS technology according to claim 42Apparatus for measuring concentration,
It is characterized in that: the compressed air interface (5) is arranged symmetrically on interconnecting piece.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910916185.3A CN110501306A (en) | 2019-09-26 | 2019-09-26 | A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910916185.3A CN110501306A (en) | 2019-09-26 | 2019-09-26 | A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110501306A true CN110501306A (en) | 2019-11-26 |
Family
ID=68592831
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910916185.3A Pending CN110501306A (en) | 2019-09-26 | 2019-09-26 | A kind of highly sensitive diesel emission NO based on TDLAS technology2Apparatus for measuring concentration |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110501306A (en) |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN207379917U (en) * | 2017-11-16 | 2018-05-18 | 中北大学 | Aero-engine gas component and density monitoring system |
| CN110261328A (en) * | 2019-07-19 | 2019-09-20 | 宁波海尔欣光电科技有限公司 | Calibrate method and device, the gas concentration analyzer of optical maser wavelength |
-
2019
- 2019-09-26 CN CN201910916185.3A patent/CN110501306A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN207379917U (en) * | 2017-11-16 | 2018-05-18 | 中北大学 | Aero-engine gas component and density monitoring system |
| CN110261328A (en) * | 2019-07-19 | 2019-09-20 | 宁波海尔欣光电科技有限公司 | Calibrate method and device, the gas concentration analyzer of optical maser wavelength |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN107144549B (en) | Detection device and method based on TDLAS trace CO gas concentration | |
| CN205374298U (en) | Trace gas concentration detection apparatus based on TDLAS | |
| US4990780A (en) | Method for determining fuel and engine oil comsumption using tunable diode laser spectroscopy | |
| CN207946353U (en) | A kind of gas concentration detection apparatus | |
| CN109991189B (en) | Fixed point wavelength modulation gas concentration measuring device based on wave number drift correction and measuring method thereof | |
| CN108106998B (en) | Atmosphere pollution detection device and detection method | |
| CN101644673A (en) | Infrared cavity ring-down spectroscopy trace gas detection method based on quantum cascade laser | |
| CN108760681A (en) | A kind of path averaged temperature measuring system and method decomposed based on waveform | |
| CN105067564B (en) | A kind of optical fiber gas concentration detection method with temperature compensation capability | |
| CN207379917U (en) | Aero-engine gas component and density monitoring system | |
| CN104280362A (en) | Online high-temperature water vapor laser spectrum detection system | |
| CN101178153A (en) | Locating method and system for city gas pipeline leakage test | |
| CN209148538U (en) | A kind of gas detecting system based on infrared absorption spectrum | |
| Xia et al. | An approach of open-path gas sensor based on tunable diode laser absorption spectroscopy | |
| CN107389606A (en) | A kind of optical path length analysis method based on tunable semiconductor laser absorption spectrum | |
| CN201152458Y (en) | Urban gas pipeline leakage detection and positioning system | |
| CN107036983B (en) | The method for realizing non-homogeneous combustion field gas parameter quantitative measurment based on modulated spectrum | |
| CN110907398A (en) | Gas concentration measuring method and measuring device | |
| Dong et al. | A mid-infrared carbon monoxide sensor system using wideband absorption spectroscopy and a single-reflection spherical optical chamber | |
| CN110261349A (en) | Gas concentration measuring method and device based on TDLAS | |
| CN206862883U (en) | Detection means based on TDLAS trace CO gas concentrations | |
| CN103592225B (en) | Soil infrared photoacoustic spectra Quick testing instrument and soil physico-chemical property assay method thereof | |
| Mo et al. | Current-modulated cavity ring-down spectroscopy for mobile monitoring of natural gas leaks | |
| CN109270008A (en) | A kind of burning gas temperature and multicomponent concentration measuring method and system based on TDLAS | |
| CN108333143A (en) | A kind of vapour concentration measurement modification method based on tunable diode laser absorption spectrometry |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20191126 |