CN102156112A - Flue gas flow velocity measuring device and method - Google Patents
Flue gas flow velocity measuring device and method Download PDFInfo
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- CN102156112A CN102156112A CN 201110054000 CN201110054000A CN102156112A CN 102156112 A CN102156112 A CN 102156112A CN 201110054000 CN201110054000 CN 201110054000 CN 201110054000 A CN201110054000 A CN 201110054000A CN 102156112 A CN102156112 A CN 102156112A
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Abstract
The invention discloses a flue gas flow velocity measuring device and method. The flue gas flow velocity measuring device comprises two groups of light emitting systems and light receiving systems which are respectively arranged at two sides of a flue, wherein each light emitting system comprises an LED light source and a collimating lens located on an exiting light path of the LED light source; each light receiving system comprises a focusing lens and a photoelectric detector located on a transmittance light path of the focusing lens; light beams emitted by the LED light source are collimated to parallel light beams through the collimating lens and then to pass through the flue, then the parallel light beams are received by the focusing lens and sent to the photoelectric detector; and a digital display is connected outside the photoelectric detector through a data processing system. In the invention, a high frequency flash signal caused by temperature fluctuation can be measured, and a low frequency flash signal caused by smoke dust concentration fluctuation can also be processed at the same time; a light flash signal can be obtained under the condition that the turbulent flow of a flue refractive index is very weak (light velocity and flow meters can not be adopted); and the flue gas flow velocity measuring device has the characteristics of high measurement precision, non-interference, convenience for installation, broader application range and the like.
Description
Technical field
The present invention relates to the pipe flow speed field of measuring technique, be specifically related to a kind of flue gas flow rate measuring instrument and measuring method.
Background technology
Particle all has very serious harm to every field such as human health, commercial production, ecologic environments.And to control, administer pollution, and must carry out the on-line continuous monitoring to the pollutant emission of industrial enterprise, the particle concentration and the total emission volumn of discharging are accurately measured.In the fume emission monitoring instrument, the instrument of measuring flue gas flow rate degree and particle concentration is a lot, wherein adopting the measurement of optical flare method is a kind of monitoring method with unique superiority, and it has adopted the optical flare technology of non-intervention type to measure flue gas flow rate and particle concentration simultaneously.Because its non-invasi, reduced maintaining time, increased serviceable life, and can be under unusual opposite extreme situations, use in the environment as explosive, high temperature, compare with the light decay subtraction, also have simple in structure, the advantage of stable performance.
U.S. OSI(Optical Scientific Inc.) be the producer of external unique production optical flow speed sensors (OFS), American National Environmental Protection Administration approved is with the technical standard of OFS as fluid-velocity survey, and the optics velocimeter of its production has been widely used in the monitoring of factory's gas pollutant discharging.This optics velocimeter adopts the structure of single light source, double detector, and receiving port footpath diameter is a centimetre magnitude, the about 2cm of two hole centre distances.According to existing theoretical, the characteristic frequency of the optical flare that measures equals the ratio of flue gas flow rate and receiver lens diameter.Suppose flue gas flow rate at 10m/s, then move the characteristic frequency of the flicker that causes 10 by particle
3About Hz, uniformity of temperature profile in flue gas stream, under the very weak situation of refractive index fluctuation, the OFS velocimeter is measured less than flow velocity.Because two receiver lenss distance is too near, can not utilize that frequency is lower, the scale dependent flue gas concentration of big (suitable) optical flare that rises and falls and cause with the diameter of flue.
On measuring method based on particle Extinction Characteristic optical flare that stochastic distribution causes, how tame units such as domestic Tsing-Hua University, Zhejiang University, Shanghai University of Science and Technology have all carried out the research of similar work, but also there is big defective in actual applications in their work, its reason mainly contains three: 1) when the particle of process light beam is too many, the optical flare signal very a little less than, energy measurement not when promptly dust concentration is too high; 2) few in order to make, must adopt laser beam measuring, and the noise of laser is in standard deviation that the 0.01(relative light intensity rises and falls through the particle of light beam) about, so dust concentration can not measure the optical flare signal when low.3) in principle, this method has a fatal weakness: it is consistent being glimmered with refractive index (temperature) by the characteristic frequency that flicker had of particle stochastic distribution, all relevant with the ratio of beam diameter with flow velocity.Therefore unlikely refractive index is glimmered therefrom deducted, and can not get dust concentration accurately, is a kind of method that lacks of prospects.
Summary of the invention
The purpose of this invention is to provide a kind of flue gas flow rate measuring instrument and measuring method, simple crosscorrelation when in flue gas, propagating and the design of optical flare effect based on two-beam, actual conditions according to flue gas stream, can in a big way, change two distances that receive between pupil, increase the ability of handling the low frequency optical flare signal that rises and falls because of dust concentration, the flow velocity of being surveyed is the arithmetic mean on the light path, is easy to accurately calculate discharge capacity.
Technical scheme of the present invention is as follows:
A kind of flue gas flow rate measuring instrument, it is characterized in that: include light emission system and optical receiver system that two components are located at the flue both sides, wherein light emission system includes led light source and the collimation lens that is positioned on the led light source emitting light path, optical receiver system includes condenser lens and the photodetector that is positioned on the condenser lens transmitted light path, the light beam that described led light source sends passes flue after the collimation lens collimation is for parallel beam, receive and send into photodetector by condenser lens again; Described photodetector is by the external digital indicator of data handling system.
A kind of flue gas flow rate measuring method, it is characterized in that: it specifically may further comprise the steps: in the both sides of flue two groups of light emission systems and optical receiver system are installed respectively, wherein light emission system includes led light source and the collimation lens that is positioned on the led light source emitting light path, optical receiver system includes condenser lens and the photodetector that is positioned on the condenser lens transmitted light path, photodetector is by the external digital indicator of data handling system, the light beam that led light source sends passes flue after the collimation lens collimation is for parallel beam, receive and send into photodetector by condenser lens again, photodetector is transformed into electric signal with the light signal of sending into, be sent to data handling system then and carry out filtering, detection and processing and amplifying also obtain the time-variable data of logarithm light intensity, calculate the flow velocity of flue gas in the flue and the particle concentration in the flue gas at last, and send the flow velocity of flue gas and the particle concentration information in the flue gas to digital indicator and show.
Described flue gas flow rate measuring instrument is characterized in that: described led light source is driven by constant current source.
Described flue gas flow rate measuring instrument is characterized in that: the front end of described condenser lens is equipped with dust cover.
The present invention has used the split-type structural of two light sources, double detector, can change two distances that receive between pupil according to the actual conditions of flue in a big way.
The present invention has increased the ability of handling the low frequency optical flare that causes because of the dust concentration fluctuating, can measure the optical flare signal under the very faint situation of uniformity of temperature profile, refractive index fluctuation.
The present invention adopts large-power light-emitting diodes, and the small-bore transmits and receives, and is smoothly little to the flash signal aperture, thereby increased the reliability of measurement flow rate when flash signal is more weak.
The simple crosscorrelation expression formula that receives two ways of optical signals is
In the formula, K
0Be the space wave number in the flue, v (z) be flow velocity,
Be the mean distance between two light beams,
For time delay, L are that beam Propagation distance, k are the light wave numbers, transmit and receive the aperture and use respectively
With
Expression,
,
Be respectively zeroth order and single order Bessel function,
It is the spectrum of refractive index imaginary part.Utilize the cross correlation function curve, be easy to calculate flow velocity, for example for maximum cross correlation, satisfy condition time delay
Can calculate mean flow rate thus.By the weights function that formula (1) is derived, the flow velocity that is easy to prove measurement is the arithmetic mean on the light path, therefore than the discharge capacity of the easier calculating flue gas of OFS velocimeter.
Experience shows: logarithm light intensity fluctuation standard deviation
With particle mean concentration m
0Satisfy relation
Therefore, providing calibration coefficient with weight method
After, be easy to obtain mean concentration m
0
Beneficial effect of the present invention:
(1), the present invention is a light source with the LED through high frequency modulated, light arrives optical receiver system after flue is propagated, the arrival photodetector carries out opto-electronic conversion after being focused lens focus, and electric signal enters data processing equipment after signal processing circuit, the measuring accuracy height.
(2), the present invention has used the split-type structural of two light sources, double detector, based on the space correlation yardstick of flue dust optical flare characteristics, can in a big way in, change the distances between two reception pupils according to the actual conditions of flue much larger than refractive index flicker scale dependent.
(3), the present invention not only can measure the high frequency flicker that is caused by temperature fluctuation, can also be according to the needs of industry spot, the low frequency optical flare signal that causes that processing rises and falls because of dust concentration, when making it measure uniformity of temperature profile, there is particle concentration to change the flicker that causes under the very faint situation of refractive index fluctuation.
(4), the measured flow velocity of the present invention, be the arithmetic mean on the light path, the easier calculating that is used for smoke discharge amount, and measurement result is more accurate.
(5), the present invention adopts large-power light-emitting diodes, the small-bore transmits and receives, and is little to the flash signal decay, thereby increased the reliability of weak flash signal time institute velocity measurement.
Description of drawings
Fig. 1 is the structural representation of light emission system of the present invention.
Fig. 2 is the structural representation of optical receiver system of the present invention, and wherein the figure (a) and (b) are respectively the structural drawing of the optical receiver system under two different angles.
Fig. 3 is a structure principle chart of the present invention.
Fig. 4 is a data processor surface chart of the present invention.
Embodiment
Referring to Fig. 1,2,3, a kind of flue gas flow rate measuring instrument, include two components and be located at the light emission system and the optical receiver system of flue both sides, wherein light emission system includes led light source 2 and the collimation lens 3 that is positioned on led light source 2 emitting light paths, optical receiver system includes condenser lens 5 and the photodetector 6 that is positioned on condenser lens 5 transmitted light paths, the light beam that led light source 2 sends passes flue after collimation lens 3 collimations are for parallel beam, receive and send into photodetector by condenser lens 5 again; Photodetector is by the external digital indicator 9 of data handling system.
Led light source 2 is driven by constant current source 1; The front end of condenser lens 5 is equipped with dust cover 4.
A kind of flue gas flow rate measuring method, specifically may further comprise the steps: two groups of light emission systems and optical receiver system are installed respectively in the both sides of flue, wherein light emission system includes led light source and the collimation lens that is positioned on the led light source emitting light path, optical receiver system includes condenser lens and the photodetector that is positioned on the condenser lens transmitted light path, photodetector is by the external digital indicator of data handling system, the light beam that led light source sends passes flue after the collimation lens collimation is for parallel beam, receive and send into photodetector by condenser lens again, photodetector is transformed into electric signal with the light signal of sending into, be sent to data handling system then and carry out filtering, detection and processing and amplifying also obtain the time-variable data of logarithm light intensity, calculate the flow velocity of flue gas in the flue and the particle concentration in the flue gas at last, and send the flow velocity of flue gas and the particle concentration information in the flue gas to digital indicator and show.
The present invention is further illustrated below in conjunction with accompanying drawing:
Light beam is gone into optical receiver system through flue is laggard, focuses on the photodetector 6 through being focused lens 5 behind the dustproof window 4, and the useful detection area of photodetector 6 is 5*5mm
2, the spot diameter after the focusing is 1.5mm.7 pairs of signals of circuit board carry out preposition amplification and bandpass filtering, and the filter center frequency is consistent with modulating frequency.8 pairs of flash signals of circuit board are handled, and comprise detection, filtering and amplification, guarantee only signal to be amplified, and ground unrest is not influenced substantially, have improved signal to noise ratio (S/N ratio).Can be directly show that through the electric signal of circuit board 8 so that real-time regulated led light source intensity, avoid taking place saturated, the while can utilize 16 capture cards to gather to computing machine, carries out real-time data processing and calculating at the digital indicator 9 of receiving system tail end.In the data handling procedure, can adopt two kinds of patterns of single step collection and continuous acquisition, and can regulate sample frequency, mean time, level and smooth point, interpolation point and average time at any time as required, with real-time being presented on the screen of the result of calculation of flue gas flow rate and particle concentration, increased the dirigibility of data processing.
During experiment, two led light sources are installed in a side of flue, and both lines are parallel with the flow of flue gas direction.Optical receiver system lays respectively at the right opposite of two light sources.Behind the light signal process flue that the led light source of path one end sends, the detection system that enters the other end.Because through collimation, its light beam can not enter another detection system except that its opposite to light source.
Concrete measuring principle is as follows:
The double light path correlation flue gas flow rate and the measuring concentration of granules in certain system that utilize the present invention to propose are divided into real part and imaginary part two parts with refractive index, and according to theoretical derivation as can be known, particle concentration changes the light intensity fluctuation related function that causes and can be expressed as:
(1)
In the formula, K
0Be the space wave number in the flue, v (z) be flow velocity,
Be the mean distance between two light beams,
For time delay, L are that beam Propagation distance, k are the light wave numbers, transmit and receive the aperture and use respectively
With
Expression,
,
Be respectively zeroth order and single order Bessel function,
It is the spectrum of refractive index imaginary part.Utilize the cross correlation function curve, be easy to calculate flow velocity, for example for maximum cross correlation, satisfy condition time delay
Can calculate mean flow rate thus.By the weights function that formula (1) is derived, the flow velocity that is easy to prove measurement is the arithmetic mean on the light path, therefore than the discharge capacity of the easier calculating flue gas of OFS velocimeter.
Experience shows: logarithm light intensity fluctuation standard deviation
With particle mean concentration m
0Satisfy relation
Therefore, providing calibration coefficient with weight method
After, be easy to obtain mean concentration m
0
Claims (4)
1. flue gas flow rate measuring instrument, it is characterized in that: include light emission system and optical receiver system that two components are located at the flue both sides, wherein light emission system includes led light source and the collimation lens that is positioned on the led light source emitting light path, optical receiver system includes condenser lens and the photodetector that is positioned on the condenser lens transmitted light path, the light beam that described led light source sends passes flue after the collimation lens collimation is for parallel beam, receive and send into photodetector by condenser lens again; Described photodetector is by the external digital indicator of data handling system.
2. flue gas flow rate measuring method, it is characterized in that: it specifically may further comprise the steps: in the both sides of flue two groups of light emission systems and optical receiver system are installed respectively, wherein light emission system includes led light source and the collimation lens that is positioned on the led light source emitting light path, optical receiver system includes condenser lens and the photodetector that is positioned on the condenser lens transmitted light path, photodetector is by the external digital indicator of data handling system, the light beam that led light source sends passes flue after the collimation lens collimation is for parallel beam, receive and send into photodetector by condenser lens again, photodetector is transformed into electric signal with the light signal of sending into, be sent to data handling system then and carry out filtering, detection and processing and amplifying also obtain the time-variable data of logarithm light intensity, calculate the flow velocity of flue gas in the flue and the particle concentration in the flue gas at last, and send the flow velocity of flue gas and the particle concentration information in the flue gas to digital indicator and show.
3. flue gas flow rate measuring instrument according to claim 1 is characterized in that: described led light source is driven by constant current source.
4. flue gas flow rate measuring instrument according to claim 1 is characterized in that: the front end of described condenser lens is equipped with dust cover.
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| CN 201110054000 CN102156112B (en) | 2011-03-08 | 2011-03-08 | Flue gas flow velocity measuring device and method |
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|---|---|---|---|
| CN 201110054000 CN102156112B (en) | 2011-03-08 | 2011-03-08 | Flue gas flow velocity measuring device and method |
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| CN102156112A true CN102156112A (en) | 2011-08-17 |
| CN102156112B CN102156112B (en) | 2013-01-23 |
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Cited By (13)
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| CN104374950A (en) * | 2014-11-17 | 2015-02-25 | 上海理工大学 | Engine combustion flow field speed measuring device and method based on flame radiation characteristics |
| TWI481873B (en) * | 2013-03-22 | 2015-04-21 | Giga Byte Tech Co Ltd | Air velocity measuring system and method thereof |
| CN104777326A (en) * | 2014-09-26 | 2015-07-15 | 北京瑞德先飞科技有限公司 | Particle counting instrument with flow speed automatic monitoring and real-time calibration functions |
| CN105571663A (en) * | 2016-02-16 | 2016-05-11 | 安徽理工大学 | Single gas extraction borehole small flow testing device based on smoke particle migration |
| CN107110882A (en) * | 2014-12-22 | 2017-08-29 | 高丽大学校产学协力团 | Fluid velocity determines device |
| CN108760687A (en) * | 2018-04-08 | 2018-11-06 | 深圳市天环通科技有限公司 | Laser light scattering cooking fume instrument |
| CN109764909A (en) * | 2019-01-22 | 2019-05-17 | 中国科学院合肥物质科学研究院 | A kind of monitoring system and method for discharge gas flow velocity and particulate matter component |
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| CN112798483A (en) * | 2020-12-31 | 2021-05-14 | 山东大学 | Flat miniature smoke detection sensor and working method thereof |
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| TWI481873B (en) * | 2013-03-22 | 2015-04-21 | Giga Byte Tech Co Ltd | Air velocity measuring system and method thereof |
| CN104777326A (en) * | 2014-09-26 | 2015-07-15 | 北京瑞德先飞科技有限公司 | Particle counting instrument with flow speed automatic monitoring and real-time calibration functions |
| CN104374950B (en) * | 2014-11-17 | 2018-04-20 | 上海理工大学 | Engine burn flow field velocity measuring device and method based on flame radiation |
| CN104374950A (en) * | 2014-11-17 | 2015-02-25 | 上海理工大学 | Engine combustion flow field speed measuring device and method based on flame radiation characteristics |
| CN107110882A (en) * | 2014-12-22 | 2017-08-29 | 高丽大学校产学协力团 | Fluid velocity determines device |
| CN105571663A (en) * | 2016-02-16 | 2016-05-11 | 安徽理工大学 | Single gas extraction borehole small flow testing device based on smoke particle migration |
| CN108760687A (en) * | 2018-04-08 | 2018-11-06 | 深圳市天环通科技有限公司 | Laser light scattering cooking fume instrument |
| CN109764909A (en) * | 2019-01-22 | 2019-05-17 | 中国科学院合肥物质科学研究院 | A kind of monitoring system and method for discharge gas flow velocity and particulate matter component |
| CN109764909B (en) * | 2019-01-22 | 2021-08-06 | 中国科学院合肥物质科学研究院 | System and method for monitoring flow velocity of exhaust gas and particulate matter components |
| US10801872B1 (en) | 2019-08-06 | 2020-10-13 | Surface Solutions Inc. | Methane monitoring and conversion apparatus and methods |
| CN110879300A (en) * | 2019-10-11 | 2020-03-13 | 中国航发沈阳发动机研究所 | Method and system for measuring velocity of flowing particles |
| CN110879301A (en) * | 2019-10-11 | 2020-03-13 | 中国航发沈阳发动机研究所 | Method and system for simultaneously measuring two-dimensional distribution of liquid concentration and liquid movement |
| CN112362110A (en) * | 2020-11-24 | 2021-02-12 | 湖南核三力技术工程有限公司 | Pneumatic cut tobacco conveying speed and flow measuring method and device based on parallel light coverage |
| CN112798483A (en) * | 2020-12-31 | 2021-05-14 | 山东大学 | Flat miniature smoke detection sensor and working method thereof |
| CN115877032A (en) * | 2022-12-08 | 2023-03-31 | 青岛众瑞智能仪器股份有限公司 | Method for detecting flue gas flow velocity by light interference scintillation method and novel flue gas flow velocity measuring instrument |
| CN115877032B (en) * | 2022-12-08 | 2023-08-08 | 青岛众瑞智能仪器股份有限公司 | Method for detecting smoke flow velocity by optical interference scintillation method and smoke flow velocity measuring instrument |
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