CN105319183A - Detector and detection method for real-time on-line detection of emission smoke intensity of diesel engine - Google Patents
Detector and detection method for real-time on-line detection of emission smoke intensity of diesel engine Download PDFInfo
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- CN105319183A CN105319183A CN201510777375.3A CN201510777375A CN105319183A CN 105319183 A CN105319183 A CN 105319183A CN 201510777375 A CN201510777375 A CN 201510777375A CN 105319183 A CN105319183 A CN 105319183A
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Abstract
The invention provides a detector and a detection method for real-time on-line detection of the emission smoke intensity of a diesel engine. The detection method comprises the following steps: firstly, selecting a proper tunable laser; utilizing a laser controller to control laser output; enabling the output wavelength of the laser to be scanned nearby the gas molecule absorption peak at a certain frequency; enabling a modulated optical signal to pass through a tested gas; utilizing a photoelectric detector to detect the optical signal passing through the gas; inputting a converted electrical signal into a phase-locked amplifier; analyzing a harmonic signal, wherein the analysis on the harmonic signal comprises the following substeps: calculating to obtain the real concentration value of the gas molecules by use of the ratio of the peak value of second harmonics to the peak value of first harmonics in the harmonic signal, performing inversion to obtain a corresponding second harmonic peak value, and calculating the relationship between the second harmonic errors and the concentration of emission particles. The detector and the detection method can not only realize real-time on-line detection of the concentration of exhaust emission particles of the diesel engine but also effectively avoid influences on the measured value from the light source energy and environmental factors in the light transmission method.
Description
Technical field
What the present invention relates to is a kind of diesel emission smoke intensity pick-up unit and method, specifically a kind of device and method utilizing infrared band spectral absorption and modulation-demodulation technique to carry out the detection of diesel emission smoke intensity.
Background technology
Increasingly serious along with problem of environmental pollution, diesel engine is as modern industry and indispensable propulsion system of living, and its emission problem more and more receives publicity.The exhaust contaminant of engine mainly comprises gaseous contaminant and particle.Particle PM refers to be no more than in the diluted exhaust of 325K (52 DEG C), by all substances that the filter medium specified is collected in temperature.Cigarette refers to be suspended in diesel exhaust gas stream, can absorb, reflect or the particle of refracted ray.Smoke intensity is an index of tolerance cigarette.The various particles that engine discharges in air, the healthy and safe of ecologic environment and the mankind in serious threat, therefore from the angle of sustainable development, must carry out effective detection and control to engine particulate matter discharge and smoke intensity.
At present, in the world two kinds are mainly contained to the apparatus measures method of diesel emission smoke intensity: 1. filtration method: with a certain amount of exhaust sample gas by filter paper, with the carbon granules weight that filter paper stays or compare and measure with the light reflectivity of its surface.2. light transmission method: utilize exhaust stream particle extinction characteristic to measure, namely measure with the permeability of the diametric light at exhaust outlet certain distance.Filtration method needs to carry out the long period to emission and collects sampling, and the particulate component adsorptive power of different filter paper to different size is distinguished effectively greatly, its measuring accuracy is not high, because filter type smokemeter is only the dye blackness of exhaust particulate to filter paper, and do not consider the impact of the factor such as blue smoke, white cigarette, so measuring the tail gas under steady state condition still more accurately.But under transient condition, the measurement that filter type smokemeter can not complete moment or continue.The saturating formula smokemetor of light can reflect the exhaust emissions under engine transient operation really, be directed to filter paper method and there is obvious advantage, utilize light transmission method can to measure in real time the particle in diesel emission, the transient state particle concentration in diesel emission is obtained according to Mie-scattering lidar, but its shortcoming is also comparatively obvious, light transmission method is differentiated by the part luminous energy of particulate adsorbent or scattering according to light source, it is subject to light intensity self fluctuation and such environmental effects is comparatively large, has certain limitation in test process.
Summary of the invention
The object of the present invention is to provide a kind of diesel emission smoke intensity real-time online detector that can realize high precision real-time online measuring.The object of the present invention is to provide a kind of diesel emission smoke intensity real-time on-line detecting method.
Diesel emission smoke intensity real-time online detector of the present invention comprises detection cell, tunable laser, laser controller, photodetector, lock-in amplifier and computing machine, the tail gas of diesel engine enters in detection cell, laser controller controls tunable laser and exports modulated laser irradiating and detecting pond, photodetector to carry out through light reception detection and by electric signal transmission to lock-in amplifier, the data after lock-in amplifier analyzing and processing are by Computer display.
Diesel emission smoke intensity real-time on-line detecting method of the present invention is:
First the absorption peak spectral line for certain gas composition in diesel emission chooses suitable tunable laser, utilize laser controller to control laser instrument to export, make the output wavelength of laser instrument near gas molecules sorb peak with certain frequency sweeping, by the light signal after modulation by tested gas, photodetector is utilized to detect the light signal by gas, and the electric signal after conversion is input in lock-in amplifier, analyze its harmonic signal; Its harmonic signal of described analysis specifically comprises: first utilize the crest value ratio calculation of the crest value of second harmonic in harmonic signal and first harmonic to draw the actual concentration value of gas molecule, and then be finally inversed by corresponding second harmonic peak value, the relation of particle concentration in calculating second harmonic error by the Mie-scattering lidar of particle and discharge.
Diesel emission smoke intensity real-time on-line detecting method of the present invention can also comprise:
1, in sweep signal, high frequency sinusoidal signal is loaded.
2, make the output wavelength of laser instrument described in in certain frequency sweeping process near gas molecules sorb peak, employing low frequency sawtooth is sweep signal, and frequency is 200Hz.
3, the frequency of described high frequency sinusoidal signal is 10kHz, peak value is 4mA.
The present invention is the problem being difficult to realize high precision real-time online measuring in order to solve existing diesel emission smoke intensity meter, provides a kind of optical non-contact smoke intensity testing tool and method.The present invention adopts spectral absorption method, Mie-scattering lidar is combined with harmonic modulation theory, can realize detecting the real-time online of exhaust emissions of diesel engine particle concentration, measured value in light transmission method effectively can be avoided again to be subject to the impact of energy of light source and environmental factor, better can to solve the testing requirement of particle concentration in diesel engines at present discharge.
The diesel emission smoke intensity high precision real-time online testing device that realizes of the present invention comprises diesel engine 1, detection cell 2, tunable laser 3, laser controller 4, photodetector 5, lock-in amplifier 6, computing machine 7.Exhaust emissions is entered in detection cell 2 in diesel engine 1 operational process, laser controller 4 controls tunable laser 3 and exports the modulated laser meeting test needs, utilize photodetector 5 to carrying out reception detection through light, and by electric signal transmission to lock-in amplifier 6, the data by analysis after process are shown to user by computing machine 7.
Diesel emission smoke intensity high precision real-time in-line testing method of the present invention, first for certain gas composition in diesel emission (as NO, CO etc.) absorption peak spectral line choose suitable tunable laser, utilize laser controller to control laser instrument to export, make its output wavelength near gas molecules sorb peak with certain frequency sweeping, simultaneously for eliminating low frequency ground unrest to the impact of measuring accuracy, swept-frequency signal loads high frequency sinusoidal signal, by the light signal after modulation by tested gas, photodetector is utilized to detect the light signal by gas, and the electric signal after conversion is input in lock-in amplifier, analyze its harmonic signal, concretely: the peak value carrying out the first harmonic after Fourier series conversion and second harmonic through lock-in amplifier is all directly proportional to signal light intensity, the peak value of second harmonic is directly proportional to the concentration of gas molecule, and when in discharge, particle concentration is different, the peak value of second harmonic can be caused to change to some extent, according to this corresponding relation, first the crest value ratio calculation of the crest value of second harmonic in harmonic signal and first harmonic is utilized to draw the actual concentration value (strong point of delustering because ratio is reducible of gas molecule, effectively can avoid the error that the decay of particle to light intensity brings), and then be finally inversed by corresponding second harmonic peak value, and the actual second harmonic peak value measured produces under particle impact, therefore deviation is had between the two, namely this deviation is caused by the particle in discharge, the relation of particle concentration in can calculating second harmonic error by the Mie-scattering lidar of particle and discharge.
The present invention adopts tunable laser as probe source, belongs to non-contact type test method, utilizes low frequency sawtooth to load the method for high_frequency sine wave modulation signal, effectively avoids low-frequency noise on the impact of detection; For the feature that the peak value of first harmonic in modulation signal and second harmonic is all directly proportional to initial beam intensity, adopt ratio erasure signal light self fluctuation of harmonic signal and environmental factor on the impact of test result; Utilize the ratio of second harmonic and first harmonic to be finally inversed by the actual concentration of gas composition, and then anti-release the peak value descending second harmonic without particle reflection, utilize peak difference before and after second harmonic in conjunction with Mie-scattering lidar, calculate smoke intensity value in diesel emission.
Accompanying drawing explanation
Fig. 1 is diesel emission smoke intensity real-time online detector schematic diagram of the present invention.
Embodiment
Illustrate below and the present invention is described in more detail.
Diesel emission smoke intensity high precision real-time in-line testing method is realized described in present embodiment, choose tunable laser 3 as probe source, its output characteristics is with control electric current linear change, comprise its output wavelength and power, because the gas molecule in diesel emission has different absorption peak spectral lines, therefore when choosing laser instrument, its wavelength output characteristics must be corresponding with the absorption peak of certain gas molecule.Utilize laser controller 4, control laser instrument and make its output wavelength near gas molecules sorb peak with certain frequency sweeping, low frequency sawtooth is adopted to be sweep signal in this invention, frequency is 200Hz, simultaneously for eliminating low frequency ground unrest to the impact of measuring accuracy, swept-frequency signal loads high frequency sinusoidal signal, adopt frequency to be 10kHz peak-to-peak value to be the modulation signal of 4mA in this invention, by the light signal after modulation by detection cell 2, the tail gas of discharging during diesel engine 1 runs can be accessed by detection cell 2, detection cell 2 can be put into diesel engine 1 gas outlet when diesel exhaust gas amount is larger, photodetector 5 is utilized to detect the light signal by gas, because tunable laser 2 carries out surface sweeping for the absorption peak of gas molecule in the course of the work, therefore its output will produce larger light loss at gas absorption peak place, then the electric signal after conversion is input in lock-in amplifier 6, the electric signal that detector exports can be carried out Fourier series change by lock-in amplifier 6, and computational analysis is carried out in frequency domain, effectively can eliminate the noise in time domain, smoke intensity value calculates concretely: the peak value carrying out the first harmonic after Fourier series conversion and second harmonic through lock-in amplifier is all directly proportional to signal light intensity, the peak value of second harmonic is directly proportional to the concentration of gas molecule, and the particle in discharge can produce attenuation to light intensity, when in discharge, particle concentration is different, the peak value of second harmonic can be caused to change to some extent, namely the present invention calculates the smoke intensity value in diesel emission according to this corresponding relation, first the crest value ratio calculation of the crest value of second harmonic in harmonic signal and first harmonic is utilized to draw the actual concentration value (strong point of delustering because ratio is reducible of gas molecule, effectively can avoid the error that the decay of particle to light intensity brings), and then be finally inversed by second harmonic peak value corresponding under actual concentration, and the actual second harmonic peak value measured produces under particle impact, therefore deviation is had between the two, namely this deviation is caused by the particle in discharge, the relation of particle concentration in can calculating second harmonic error by the Mie-scattering lidar of particle and discharge.
Claims (6)
1. a diesel emission smoke intensity real-time online detector, it is characterized in that: comprise detection cell, tunable laser, laser controller, photodetector, lock-in amplifier and computing machine, the tail gas of diesel engine enters in detection cell, laser controller controls tunable laser and exports modulated laser irradiating and detecting pond, photodetector to carry out through light reception detection and by electric signal transmission to lock-in amplifier, the data after lock-in amplifier analyzing and processing are by Computer display.
2. a diesel emission smoke intensity real-time on-line detecting method, it is characterized in that: the absorption peak spectral line first for certain gas composition in diesel emission chooses suitable tunable laser, utilize laser controller to control laser instrument to export, make the output wavelength of laser instrument near gas molecules sorb peak with certain frequency sweeping, by the light signal after modulation by tested gas, photodetector is utilized to detect the light signal by gas, and the electric signal after conversion is input in lock-in amplifier, analyze its harmonic signal; Its harmonic signal of described analysis specifically comprises: first utilize the crest value ratio calculation of the crest value of second harmonic in harmonic signal and first harmonic to draw the actual concentration value of gas molecule, and then be finally inversed by corresponding second harmonic peak value, the relation of particle concentration in calculating second harmonic error by the Mie-scattering lidar of particle and discharge.
3. diesel emission smoke intensity real-time on-line detecting method according to claim 2, is characterized in that: in sweep signal, load high frequency sinusoidal signal.
4. the diesel emission smoke intensity real-time on-line detecting method according to Claims 2 or 3, it is characterized in that: described in make the output wavelength of laser instrument near gas molecules sorb peak with in certain frequency sweeping process, employing low frequency sawtooth is sweep signal, and frequency is 200Hz.
5. diesel emission smoke intensity real-time on-line detecting method according to claim 3, is characterized in that: the frequency of described high frequency sinusoidal signal is 10kHz, peak value is 4mA.
6. diesel emission smoke intensity real-time on-line detecting method according to claim 4, is characterized in that: the frequency of described high frequency sinusoidal signal is 10kHz, peak value is 4mA.
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| CN107677575A (en) * | 2017-09-30 | 2018-02-09 | 合肥朗伯光电传感技术有限公司 | Single beam laser measures flue gas particles and the device and method of oxygen gas concentration |
| CN108204957A (en) * | 2016-12-20 | 2018-06-26 | 中国科学院工程热物理研究所 | The method and system that the temperature and component of aeroplane engine tail gas measure simultaneously |
| CN110501305A (en) * | 2019-09-09 | 2019-11-26 | 安徽岩芯光电技术有限公司 | A kind of detection device and method of vehicle exhaust |
| CN110608890A (en) * | 2019-08-05 | 2019-12-24 | 济南天业工程机械有限公司 | Engineering machine tool discharges test system |
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| CN112798538A (en) * | 2021-02-01 | 2021-05-14 | 瑞谱医疗设备(东莞)有限公司 | Method for judging existence of bacteria in blood |
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| CN114998842A (en) * | 2022-08-03 | 2022-09-02 | 广东电网有限责任公司肇庆供电局 | Power machine room smoke detection method and system based on disturbance amplification |
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Cited By (10)
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| CN106383097A (en) * | 2016-11-16 | 2017-02-08 | 浙江多普勒环保科技有限公司 | Tunable-laser-based motor vehicle exhaust gas remote sensing detection system and method |
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| CN108204957A (en) * | 2016-12-20 | 2018-06-26 | 中国科学院工程热物理研究所 | The method and system that the temperature and component of aeroplane engine tail gas measure simultaneously |
| CN107677575A (en) * | 2017-09-30 | 2018-02-09 | 合肥朗伯光电传感技术有限公司 | Single beam laser measures flue gas particles and the device and method of oxygen gas concentration |
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| CN110907396A (en) * | 2019-12-14 | 2020-03-24 | 河南省计量科学研究院 | Vehicle tail gas remote measuring device and method based on quantum cascade laser |
| CN112798538A (en) * | 2021-02-01 | 2021-05-14 | 瑞谱医疗设备(东莞)有限公司 | Method for judging existence of bacteria in blood |
| CN113504167A (en) * | 2021-08-06 | 2021-10-15 | 深圳市量宇科技有限公司 | Ultra-low concentration particulate matter detection method and detection system thereof |
| CN114998842A (en) * | 2022-08-03 | 2022-09-02 | 广东电网有限责任公司肇庆供电局 | Power machine room smoke detection method and system based on disturbance amplification |
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Application publication date: 20160210 |