CN113984606A - Laser backscattering dust meter with background light compensation function and use method thereof - Google Patents
Laser backscattering dust meter with background light compensation function and use method thereof Download PDFInfo
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- CN113984606A CN113984606A CN202111196149.8A CN202111196149A CN113984606A CN 113984606 A CN113984606 A CN 113984606A CN 202111196149 A CN202111196149 A CN 202111196149A CN 113984606 A CN113984606 A CN 113984606A
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- 239000000428 dust Substances 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 11
- 238000005259 measurement Methods 0.000 claims abstract description 22
- 238000012937 correction Methods 0.000 claims abstract description 7
- 239000002245 particle Substances 0.000 claims abstract description 6
- 230000003287 optical effect Effects 0.000 claims description 7
- 230000000903 blocking effect Effects 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 description 2
- 238000001514 detection method Methods 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/06—Investigating concentration of particle suspensions
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- G01N15/075—
Abstract
The invention provides a laser backscattering dust instrument with a background light compensation function, which comprises: the beam splitting prism is arranged on a light path of a laser beam emitted by the laser source and divides the laser beam into two beams, wherein one beam is calibration light, and the other beam is measurement light; the calibration light enters the chimney and generates light spots on the inner wall of the chimney, and the measurement light enters the chimney and reacts with particles to form backward scattering light; the photoelectric detector is used for receiving the light signal of the light spot or the backward scattered light; and the shielding mechanism only allows one beam of light to be emitted into the chimney through the shielding mechanism at the same time. The invention also provides a using method of the laser backscattering dust meter with the background light compensation function. The invention has the advantages that the beam splitter prism and the shielding mechanism are added on the basis of the existing laser backscattering dust meter, and the automatic real-time updated background light correction coefficient can be obtained on line by matching with the use method, so that the accurate measurement result is ensured to be obtained.
Description
Technical Field
The invention relates to the technical field of laser dust measurement, in particular to a laser backscattering dust meter with a background light compensation function and a using method thereof.
Background
In the application of fixed pollution source particle detection, if the temperature of a chimney is extremely high (more than 200 ℃), the dust concentration detection by adopting the laser back scattering dust meter with convenient installation and strong adaptability has great advantages. As shown in figure 1, a laser beam 6 emitted by a laser source 3 is emitted into a chimney 1, the laser beam 6 interacts with particulate matters 2 in the chimney 1 to generate scattering, when the concentration of the particulate matters 2 is increased, the total scattering sectional area of the particulate matters 2 is increased, and the backscattered light 7 is enhanced, namely, the dust concentration C and the signal light energy Ps are in linear proportional relation. The photodetector 4 detects the optical signal of the backscattered light 7 condensed by the receiving lens 5, and then obtains the dust concentration C by linearly fitting the formula C ═ K × Ps + B. However, the background light caused by the inner wall of the chimney 1 changes with the working age, the climate and even the working condition, which causes the photoelectric detector 4 to generate serious zero drift.
To obtain an accurate backlight correction factor, the existing solutions are: 1) a zero drift compensation device, usually a potentiometer or a digital register, is provided to manually compensate the drift, which has a problem of environmental counterfeit risk; 2) the double detectors are adopted to compensate the zero drift through a real-time difference method, and the problems of complicated light path, difficult light path adjustment and double detector balance calibration and poor shock resistance exist.
Disclosure of Invention
The invention aims to provide a laser backscattering dust meter with a background light compensation function so as to solve the problems.
The invention provides a laser backscattering dust instrument with a background light compensation function, which comprises a laser source and a photoelectric detector which are arranged outside a chimney, and further comprises: the beam splitter prism is arranged on a light path of the laser beam emitted by the laser source and divides the laser beam into two beams, wherein one beam is calibration light, and the other beam is measurement light; the calibration light is emitted into the chimney and generates light spots on the inner wall of the chimney, and the measurement light is emitted into the chimney and reacts with particles to form backward scattering light; the photoelectric detector is used for receiving an optical signal of the light spot or the backward scattering light; and the shielding mechanism is arranged between the chimney and the beam splitting prism and used for shielding the calibration light or the measurement light, and only one beam of light can be emitted into the chimney through the shielding mechanism at the same time.
Preferably, the optical device further comprises a diaphragm and a receiving lens, wherein the diaphragm and the receiving lens are arranged between the chimney and the photoelectric detector, and the light spot is opposite to the diaphragm and can form an image in the photoelectric detector.
Preferably, the beam splitter prism is angularly adjustably disposed in the mount.
Preferably, the shutter mechanism includes a linear driving device and a shutter driven by the linear driving device.
Preferably, the baffle is made of black light absorbing plastic.
The invention also provides a use method of the laser backscattering dust meter with the background light compensation function, which comprises the following steps:
s1, arranging a laser back scattering dust meter outside the chimney;
s2, when the chimney is in the blowing-out state, the shielding mechanism blocks the calibration light firstly, only the measuring light enters the chimney, and at the moment, the photoelectric detector measures Pbm initial measuring background light energy0(ii) a Then the shielding mechanism blocks the measuring light and only the calibrating light is emitted into the chimney, and the photodetector measures the initial calibrating background light energy Pbc0；
S3, after the chimney works normally for a certain time, the shielding mechanism blocks the calibration light firstly, only the measuring light enters the chimney, and the energy measured by the photoelectric detector is recorded as PxiSignal light energy Psi＝Pxi-Pbm0*KbiWherein i is not less than 1, KbiAs a background light correction factor, Kb1Is a preset initial value; then the measuring light is blocked by the blocking mechanism and only enters the chimney by the calibrating light, and the energy measured by the photoelectric detector is recorded as PyiCalibrating background light energy Pbci＝Pyi-Psi，Kbi+1＝Pbci/Pbc0Wherein i is more than or equal to 1.
The invention has the advantages that the beam splitter prism and the shielding mechanism are added on the basis of the existing laser backscattering dust meter, and the use method is matched to obtain the real-time automatically updated background light correction coefficient on line, so that the time cost of taking the equipment back to a laboratory for calculation and analysis by an operator is saved, the environmental-friendly counterfeiting risk caused by artificial interference is avoided, and the accurate measurement result is ensured to be obtained.
Drawings
FIG. 1 is a schematic view of the working state of a prior art laser back scattering dust meter;
FIG. 2 is a schematic view of the working state of the laser back scattering dust meter of the present invention;
fig. 3 is a schematic structural diagram of a light splitting prism.
Element number description:
1 chimney
2 particles of
3 laser source
4 photo detector
5 receiving lens
6 laser beam
61 collimated light
62 measuring light
7 backward scattered light
8 light splitting prism
9 sheltering mechanism
10 diaphragm
Detailed Description
The following describes embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to limit the present invention.
In the description of the present invention, it should be noted that the terms "upper", "lower", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplification of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the present invention.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
As shown in fig. 2, the present invention provides a laser back scattering dust meter with a background light compensation function, which comprises a laser source 3, a beam splitter prism 8, a shielding mechanism 9, a diaphragm 10, a receiving lens 5 and a photodetector 4, which are arranged outside a chimney 1, wherein the laser source 3, the beam splitter prism 8 and the shielding mechanism 9 are all positioned above the diaphragm 10, the receiving lens 5 and the photodetector 4, and thus the arrangement is provided to help the photodetector 4 to receive back scattering light 7. The mounting position between the parts can be adjusted by those skilled in the art as required.
In a specific implementation, the laser source 3 is a 650nm red laser, which collimates the outgoing light into parallel light through a collimating lens.
The beam splitter prism 8 is disposed on the optical path of the laser beam 6 emitted from the laser light source 3, and splits the laser beam 6 into two beams, one beam being the calibration beam 61 and the other beam being the measurement beam 62. Wherein the calibration light 61 is emitted into the chimney 1 and generates a light spot on the inner wall of the chimney 1, and the measurement light 62 is emitted into the chimney 1 and interacts with the particles 2 to form backscattered light 7. The diaphragm 10, the receiving lens 5 and the photoelectric detector 4 are coaxially arranged in sequence, and the distance between the diaphragm and the chimney 1 is gradually increased. The diaphragm 10 functions as a field-of-view cut, i.e., allows only light of a specific area to enter the photodetector 4 through the receiving lens 5. The light spot position generated by the calibration light 61 on the inner wall of the chimney 1 is set to be opposite to the diaphragm 10, so that the light signal of the light spot can be received by the photoelectric detector 4 and imaged in the photoelectric detector 4, and the light source calibration and the acquisition of the related parameter information of the inner wall of the chimney 1 are facilitated. Although the measuring light 62 likewise forms a light spot on the inner wall of the chimney 1, the light signal of this light spot cannot be received by the photodetector 4 due to the limiting effect of the diaphragm 10, and only part of the backscattered light 7 can enter the photodetector 4. Since the measuring light 62 and the calibration light 61 have the same optical path and only one photodetector 4 receives the light signal, the problem of compensation of the balance between the two optical paths does not have to be taken into account during operation. The skilled person can also, if necessary, add a beam splitter prism to subdivide a beam of light from the collimated light 61, so as to achieve real-time monitoring of the stability of the laser source 3 and the contamination of the lenses located in the light path.
In one embodiment of the invention, in order to facilitate adaptation to chimneys 1 of different diameters, the beam splitter prism 8 is arranged angularly adjustable in a mounting (not shown) and is fixed in position by the mounting. The beam splitter prism 8 is specifically a half-mirror prism with a beam splitting ratio of 1:1 as shown in fig. 3.
As shown in fig. 2, a shielding mechanism 9 is provided between the chimney 1 and the beam splitter prism 8, and is used to shield the calibration light 61 or the measurement light 62. At the same time, only one beam of light can be emitted into the chimney 1 through the shielding mechanism 9. Specifically, the shutter mechanism 9 includes a linear driving device and a shutter driven by the linear driving device. The form of the linear driving device is not limited, and the linear driving device can be an electromagnet, a linear motor or an air cylinder and the like; the shape of the baffle may be various shapes such as circular, square, triangular, etc., and is preferably made of black light absorbing plastic, which in the initial state maintains the shielding of the collimated light 61.
As shown in fig. 2, the present invention further provides a method for using the aforementioned laser back scattering dust meter with background light compensation function, which comprises the following steps:
s1, arranging a laser back scattering dust meter outside the chimney 1;
s2, when the chimney 1 is in the blowing-out state, the shielding mechanism 9 firstly blocks the calibration light 61, only the measurement light 62 is emitted into the chimney 1, and at this time, the photodetector 4 measures the initial measurement background light energy Pbm0(ii) a The measurement light 62 is then blocked by the blocking mechanism 9 and only the calibration light 61 is incident on the chimney 1, while the photodetector 4 measures the initial calibration background light energy Pbc0；
S3, after the chimney 1 works normally for a certain time, the shielding mechanism 9 firstly blocks the calibration light 61, only the measuring light 62 is emitted into the chimney 1, and the energy measured by the photoelectric detector 4 is recorded as PxiSignal light energy Psi＝Pxi-Pbm0*KbiWherein i is not less than 1, KbiAs a background light correction factor, Kb1Is a preset initial value. Kb when the dust concentration in the stack 1 in the state of S2 furnace cut is 0 or negligibly low11. The measuring light 62 is then blocked by the blocking means 9 and only the calibration light 61 is incident on the chimney 1, the energy measured by the photodetector 4 being then recorded as PyiCalibrating background light energy Pbci＝Pyi-Psi，Kbi+1＝Pbci/Pbc0Wherein i is more than or equal to 1.
Along with the increase of the working time of the chimney 1, the control system can control the laser backscatter dust meter to repeat the step S3 at intervals, and then the control system automatically completes the background light compensation according to the algorithm calculation. An operator can obtain the real-time automatically updated background light correction coefficient on line through the method, and the accuracy of the measurement result of the laser backscatter dust meter is ensured.
The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.
Claims (6)
1. The utility model provides a laser backscatter dust meter with background light compensation function, is including setting up laser source (3) and photoelectric detector (4) outside chimney (1), its characterized in that still includes:
a beam splitter prism (8) which is arranged on the light path of the laser beam (6) emitted by the laser source (3) and divides the laser beam (6) into two beams, one beam is calibration light (61), and the other beam is measurement light (62); the calibration light (61) is emitted into the chimney (1) and generates a light spot on the inner wall of the chimney (1), and the measurement light (62) is emitted into the chimney (1) and interacts with the particles (2) to form backscattered light (7);
the photoelectric detector (4) is used for receiving an optical signal of the light spot or the backward scattering light (7);
and the shielding mechanism (9) is arranged between the chimney (1) and the beam splitting prism (8) and is used for shielding the calibration light (61) or the measurement light (62), and only one light can be emitted into the chimney (1) through the shielding mechanism (9) at the same time.
2. Laser backscatter dust meter according to claim 1, characterized by further comprising a diaphragm (10) and a receiving lens (5), the diaphragm (10) and the receiving lens (5) being arranged between the chimney (1) and the photodetector (4), the light spot facing the diaphragm (10) and being able to be imaged in the photodetector (4).
3. Laser backscatter dust meter according to claim 1, characterized in that the beam splitter prism (8) is angularly adjustably arranged in the mounting.
4. Laser backscatter dust meter according to claim 1, characterized in that the shielding mechanism (9) comprises a linear drive and a baffle driven by the linear drive.
5. The laser backscatter dust meter of claim 4, wherein the baffle is made of black light absorbing plastic.
6. A method of using the laser back scattering dust meter with background light compensation function as claimed in claim 1, comprising:
s1, arranging a laser back scattering dust meter outside the chimney (1);
s2, when the chimney (1) is in a blowing-out state, the shielding mechanism (9) firstly blocks the calibration light (61) and only the measurement light (62) is emitted into the chimney (1), and at the moment, the photoelectric detector (4) measures the initial measurement background light energy Pbm0(ii) a Then the measurement light (62) is blocked by the blocking mechanism (9) and only the calibration light (61) is emitted into the chimney (1), at which time the initial calibration background light energy Pbc is measured by the photodetector (4)0；
S3, after the chimney (1) works normally for a certain time, the shielding mechanism (9) firstly blocks the calibration light (61), only the measurement light (62) is emitted into the chimney (1), and the energy measured by the photoelectric detector (4) is recorded as PxiSignal light energy Psi＝Pxi-Pbm0*KbiWherein i is not less than 1, KbiAs a background light correction factor, Kb1Is a preset initial value; the measuring light (62) is then blocked by a blocking means (9) and only the calibration light (61) is emitted into the chimney (1), the energy measured by the photodetector (4) being recorded as PyiCalibrating background light energy Pbci＝Pyi-Psi，Kbi+1＝Pbci/Pbc0Wherein i is more than or equal to 1.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111196149.8A CN113984606A (en) | 2021-10-14 | 2021-10-14 | Laser backscattering dust meter with background light compensation function and use method thereof |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111196149.8A CN113984606A (en) | 2021-10-14 | 2021-10-14 | Laser backscattering dust meter with background light compensation function and use method thereof |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5268739A (en) * | 1990-12-04 | 1993-12-07 | Cise S.P.A. | Laser apparatus for measuring the velocity of a fluid |
| CN201210132Y (en) * | 2008-06-04 | 2009-03-18 | 太原中绿环保技术有限公司 | Laser back scattering dust measurement instrument |
| CN102519848A (en) * | 2011-11-16 | 2012-06-27 | 华中科技大学 | System and method for measuring three-dimensional volume scattering function of microparticle in water |
| CN103439232A (en) * | 2013-08-30 | 2013-12-11 | 合肥工业大学 | Obscuration type soot particle concentration measuring method and device thereof |
| CN105891070A (en) * | 2014-12-12 | 2016-08-24 | 安荣信科技(北京)有限公司 | Automatic calibration device of online continuous monitoring instrument for concentration of particulate matters |
| CN110220828A (en) * | 2019-06-25 | 2019-09-10 | 北京雪迪龙科技股份有限公司 | A kind of particle monitoring instrument |
-
2021
- 2021-10-14 CN CN202111196149.8A patent/CN113984606A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5268739A (en) * | 1990-12-04 | 1993-12-07 | Cise S.P.A. | Laser apparatus for measuring the velocity of a fluid |
| CN201210132Y (en) * | 2008-06-04 | 2009-03-18 | 太原中绿环保技术有限公司 | Laser back scattering dust measurement instrument |
| CN102519848A (en) * | 2011-11-16 | 2012-06-27 | 华中科技大学 | System and method for measuring three-dimensional volume scattering function of microparticle in water |
| CN103439232A (en) * | 2013-08-30 | 2013-12-11 | 合肥工业大学 | Obscuration type soot particle concentration measuring method and device thereof |
| CN105891070A (en) * | 2014-12-12 | 2016-08-24 | 安荣信科技(北京)有限公司 | Automatic calibration device of online continuous monitoring instrument for concentration of particulate matters |
| CN110220828A (en) * | 2019-06-25 | 2019-09-10 | 北京雪迪龙科技股份有限公司 | A kind of particle monitoring instrument |
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