CN106644986A - Online measurement device and measurement method for NO concentration in high-NO2 and low-NO atmosphere - Google Patents

Online measurement device and measurement method for NO concentration in high-NO2 and low-NO atmosphere Download PDF

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Publication number
CN106644986A
CN106644986A CN201611261453.5A CN201611261453A CN106644986A CN 106644986 A CN106644986 A CN 106644986A CN 201611261453 A CN201611261453 A CN 201611261453A CN 106644986 A CN106644986 A CN 106644986A
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sampling
air
concentration
ozone
spectrum
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陆克定
王海潮
张远航
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Peking University
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Peking University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry

Abstract

The invention discloses an online measurement device and measurement method for the NO concentration in a high-NO2 and low-NO atmosphere. The online measurement device comprises an ozone generation unit, a connection pipe cleaning unit and a sampling pipe, wherein a connection reaction bin, an NO2 measuring instrument, a second mass flow meter and a first air pump are sequentially connected behind the sampling pipe; and the connection pipe cleaning unit comprises an electromagnetic three-way valve, an activated carbon tube, a current-limiting hole and a second air pump. By adopting a cavity-enhanced absorption spectroscopy, a sampling mode (actual atmosphere of ozone is added) or a zero point mode (actual atmosphere) is set through the electromagnetic three-way valve; absorption spectrum intensity signals of two modes are measured through an NO2 measuring instrument as a sampling spectrum and a reference spectrum respectively, and then NO in the atmosphere is converted into a concentration value of the NO2 through spectral fitting, that is to say, measurement of the NO concentration in the atmosphere environment is achieved, so that the online measurement device and measurement method have the characteristics of being free of NO2 concentration interference, a low detection limit, high sensitivity, high temporal-spatial resolution, high stability and low cost.

Description

High NO2NO concentration on-line measurement devices and measuring method in low NO air
Technical field
The invention belongs to air quality field of measuring technique, is related to NO on-line measurements in air, more particularly in high NO2It is low On-line measurement device and On-line Measuring Method under NO atmospheric conditions, to NO concentration accurate measurement in air.
Background technology
Air NO is primary pollution important in convection current atmosphere, is mainly derived from the high-temp combustion of nitrogenous fuel, bag The artificial process discharge of vehicle exhaust, industrial production and coal-burning power plant is included, small part is from lightning and Microbiological release Etc. natural process discharge.NO in air, NO2, O3Photochemistry efficiency between (ozone) constitutes the base of atmospheric photochemical reaction Plinth, therefore realize that accurate measurement has highly important Atmospheric Chemistry meaning to the NO in air.
The concentration level of convection current atmosphere NO is in several ppt between hundreds of ppb, and change in concentration scope is larger.In air Free-radical chemistry research field, the accurate on-line measurement of low concentration of NO (below 100ppt) is to OH free radicals and NO in air3 The income expenditure analysis tool of free radical is of great significance, especially in typical suburb, NO in air2Concentration it is higher (several Ten ppb), the concentration relatively low (can be low up to tens ppt) of NO, under these conditions, it is difficult to realize the accurate measurement to NO.
Existing air NO measurements mainly include direct measurement and indirect measurement method.Direct measuring is mainly chemistry Luminescence method, principle is the O of the NO in air and high concentration3Reaction generates the NO of excitation state2*, the NO of excitation state2* return in decay Infrared light, the intensity and NO of infrared light can be discharged during ground state2Concentration there is preferable linear relationship, by measure light Quantum count obtains NO2Concentration, then the concentration of NO in air is obtained based on conversion ratio, but the method is examined by photon counter The restriction of survey ability so that the detectability of chemoluminescence method is restricted.Indirect measurement method is mainly by the way that air NO is turned Chemical conversion NO2Total NO is measured afterwards2Concentration (NOX), recycle NOXNO in subtractive environment2Obtain the concentration of NO, including hydrochloric acid how second two Amine AAS (luminol method), tunable diode laser absorption method (TDLAS), cavity-type BPM absorption spectrometry (CRDs) with And the technology such as laser inductive fluorescence method (LIF).
However, when there is higher NO in air2During with relatively low NO, such as air in some typical suburbs leads to Cross the NO of indirect method measurementXAnd NO2Numerical value it is larger, and measure NO be to be obtained by both subtractives, even if apparatus measures NO2Less with the uncertainty of NOx, the concentration absolute error for also resulting in the NO that subtractive is obtained is very big, therefore in high NO2It is low Under NO environmental conditions, the NO measurement results that existing NO e measurement technologies are obtained have larger uncertainty, it is difficult to realize accurate Measurement.
The content of the invention
In order to overcome the above-mentioned deficiencies of the prior art, the present invention provides NO concentration on-line measurement devices and side in a kind of air Method, with not by NO2Concentration is disturbed, the spy of low test limit, high sensitivity, high-spatial and temporal resolution, high stability and low cost Point.The present invention can be directed to high NO2The online accurate measurement of low NO air, such as in typical suburb air, NO in air2Concentration It is higher and the concentration of NO is relatively low.NO concentration of the present invention suitable for the air of online accurate measurement typical case suburb.
The present invention core be:The present invention to NO in air by being transformed using cavity reinforced absorption spectrum technology NO2Measure and measure the NO that obtains in air indirectly.It is of the invention completely different with existing traditional indirect measurement means Part be:The present invention is without the need for the NO in quantitative atmospheric environment2Concentration level, only to the NO of NO conversions2Concentration level surveyed Amount.Although the direct measurement pair of the present invention as if NO2But, the definition to reference spectra and sampling spectrum of the invention is completely not Traditional cavity reinforced absorption spectrum is same as, traditional chamber strengthens measurement NO2Technical method measures respectively zero air (or purity nitrogen Gas) and real atmosphere as reference spectra and sampling spectrum;And the present invention measures respectively real atmosphere and adds O3It is actual big Gas is used as reference spectra and sampling spectrum, then obtains NO in air by spectrum simulation and be converted into NO2Concentration value.Specifically Ground, present invention NO in measurement air2During concentration, in zero point pattern, the spectrum that collection real atmosphere is obtained is used as reference light Spectrum;In sampling configuration, high concentration O is injected in sampling process3, NO Jing are chemically converted into NO2, then measure and be converted into NO2Afterwards Spectrum as sampling spectrum;Due to the NO that the spectral intensity difference of reference spectra and sampling spectrum is only converted by NO2Cause, The NO2 absorptions that sampling spectrum and the difference of reference spectra are only converted by NO are relevant, and with real atmosphere in NO2Concentration with And others spectral absorption is unrelated.Therefore, the NO concentration that can be calculated using two kinds of spectrum in air.Using present invention side Method, without the need for the NO in real atmosphere2Carry out quantitative, but the direct measurement NO being converted into2Concentration, therefore, to air In NO measurement will not be subject to air in NO2The interference of concentration, so as to fundamentally avoid traditional NO measuring methods in it is real The NO of border air middle and high concentration2Interference, with low test limit, high sensitivity, high-spatial and temporal resolution, high stability and it is low into This characteristics of, the online accurate measurement of the NO concentration in low NO air can be realized.
The present invention provide technical scheme be:
A kind of high NO2The on-line measurement device of NO concentration in low NO air, including ozone signal generating unit, connecting tube cleaning list Unit, sampling pipe, reaction warehouse, the second mass flowmenter, the first air pump and the NO based on cavity reinforced absorption spectrum technology2Measuring instrument; Wherein, ozone signal generating unit includes pure oxygen gas, the first mass flowmenter and ozone generator, and pure oxygen gas is through the first mass Flowmeter connects ozone generator, generates O3Gas;Connecting tube cleaning unit includes three-way solenoid valve and the activity being sequentially connected Charcoal pipe, metering hole and the second air pump;The O of generation3Gas point two-way after a threeway, the first via and connecting tube cleaning unit It is connected;Second tunnel connects the rear end of sampling pipe;The rear end of sampling pipe is sequentially connected reaction warehouse, NO2Measuring instrument, the second quality stream Gauge and the first air pump;Sampling configuration or zero point pattern are arranged by three-way solenoid valve;On-line measurement device only needs a NO2 Measuring instrument (i.e. one measurement reaction chamber), measures respectively the signal of the absorption spectrum intensity of sampling configuration and zero point pattern (respectively It is called sampling spectrum and reference spectra), the concentration value that NO in air is converted into NO2 is obtained by spectrum simulation, you can realize The measurement of NO in atmospheric environment.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:The NO adopted in the device2Measuring instrument is adopted Light source be high-capacity LED monochromatic light source, the light spectral centre wavelength of transmitting is 460nm, and energy of light source is concentrated mainly on 440-480nm;High reflective mirror piece reflectivity in the measurement reaction chamber of measuring instrument is more than 99.99%.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:O3In signal generating unit, purity oxygen is through quality Flowmeter precise control flow velocity, with low discharge ozone generator is entered, and is generated by UV illumination photodissociation in ozone generator The O of steady concentration3Gas, O3Concentration level need to meet in the short time NO be fully oxidized into NO (within 1s)2
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:In connecting tube cleaning unit, three-way solenoid valve For Two In and One Out type, the first air admission hole of three-way solenoid valve is connected with ozone generator, the second air admission hole connection ambient air; The activated carbon tube of the outlet connection connecting tube cleaning unit of three-way solenoid valve, for removing the O of high concentration3, prevent to follow-up zero The oxidation damage of part, the second air pump is opened all the time and by metering hole coutroi velocity.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:Connecting tube cleaning unit ensures in electromagnetism three Port valve can quickly remove O in connecting tube during switching3Residual, realize sampling configuration and the measurement of two kinds of zero point pattern Pattern is switched fast.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:O3The gas feed flow rate of signal generating unit is much little The flow that flow is far smaller than the second mass flowmenter is set in the flow velocity of sample gas, i.e. the first mass flowmenter so that Flow changes the impact for bringing and ignores between both of which.In being embodied as, the second air pump coordinates metering hole to the present invention The speed of evacuation it is stable in 50-100ml/min, the flow velocity of the second mass flowmenter is 2.0L/min;O3Generating unit and connection Pipe cleaning unit adopts external diameter and connects for 1/8 inch of four fluorine tube.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:Calculated by accurate kinetics, instead Answer the volume in storehouse should be with sampling flow velocity and O3Concentration match, ensureing just to complete to shorten as far as possible while NO is titrated Reaction time, to reduce NO2And O3Further bring interference.In embodiments of the present invention, the volume of reaction warehouse is 30ml so that The efficiency of NO titration is more than 99%.
For above-mentioned air NO concentration on-line measurement device, it is characterised in that:By sequencing setting automatically open up or Close three-way solenoid valve and realize two kinds of measurement pattern switchings, the air in reference spectra and sampling spectrum is ensured by high frequency switching NO in environment2It is constant with the absorption of other gases.
Above-mentioned air NO concentration on-line measurement devices are using cavity reinforced absorption spectrum technology come to NO2Measure, but it is right The definition of reference spectra and sampling spectrum is totally different from traditional cavity reinforced absorption spectrum;During the device busy, specifically: In zero point pattern, the spectrum that collection real atmosphere is obtained is used as reference spectra;In sampling configuration, inject in sampling process High concentration O3, NO Jing are chemically converted into NO2, then measure and be converted into NO2Spectrum afterwards is used as sampling spectrum;Therefore, reference spectra The NO only converted by NO with the spectral intensity difference of sampling spectrum2Cause, with the NO in real atmosphere2Concentration it is unrelated.
During above-mentioned air NO concentration on-line measurement device busy, in connecting tube cleaning unit, when three-way solenoid valve connection Second air admission hole, is sampling configuration, O during the first air admission hole of closing3Reaction warehouse can be mixed into through connecting tube and sample gas, In reaction warehouse, NO complete oxidations are NO by the ozone of high concentration2And enter into NO2Measuring instrument is measured, and is evacuated power and is adopted Sample flow velocity is controlled respectively by the first air pump and the second mass flowmenter, and it is sampling spectrum now to measure the spectrum for obtaining, and spectrum is believed Number NO being totally converted comprising air NO2The NO of itself in absorption signal, atmospheric environment2Inhale caused by absorption signal, other factors Receive and scatter.Now connecting tube cleaning unit continues through the second air admission hole suction ambient air, for keeping the location mode Stable operation, and protect the second air pump.It is zero point mould when three-way solenoid valve is connected into the first air admission hole, closes the second air admission hole Formula, now the pumping flow velocity of connecting tube cleaning unit is more than O3The gas feed flow rate of generator, the O of generation3Do not enter into reaction warehouse, Whole connected tube cleaning units are taken away and are removed, and fractional-sample gas is taken away and removed also by connecting tube cleaning unit, even The gas of adapter is formed and flows backwards and clean the O remained in connecting tube3.Now NO2Measuring instrument measurement spectrum as reference spectra, Spectral signal includes the NO of itself in atmospheric environment2Absorb caused by absorption signal, other factors and scatter.Other factors cause Absorption and scattered portion absorption spectrum be it is slowly varying with wavelength, by reference to spectrum and sampling spectrum can be fallen with difference.
Using the on-line measurement device of above-mentioned low NO air NO concentration, it is possible to achieve air NO concentration is carried out online accurate Measurement.
The present invention also provides a kind of method for carrying out on-line measurement to air NO concentration, is arranged by three-way solenoid valve and is sampled Pattern or zero point pattern, in sampling configuration by generating O3Air NO is completely converted into NO by gas2, then by measuring respectively The signal of the absorption spectrum intensity of sampling configuration and zero point pattern, obtains NO in air and is converted into NO by spectrum simulation2's Concentration value, thus obtains the NO concentration in air;Specifically include following steps:
1) O is set3Signal generating unit is used to generate O3Gas;In O3Signal generating unit point two-way, first via after a threeway It is connected with connecting tube cleaning unit, connecting tube cleaning unit is by a three-way solenoid valve, activated carbon tube, metering hole and second Air pump is sequentially connected composition;Second tunnel connects the rear end of sampling pipe, and the rear end of sampling pipe is sequentially connected reaction warehouse, NO2Measuring instrument, Second mass flowmenter and the first air pump;NO2The light source that measuring instrument is adopted is high-capacity LED monochromatic light source, the light of transmitting Line spectrum centre wavelength is 460nm, and the high reflective mirror piece reflectivity measured in reaction chamber is more than 99.99%;
O3Signal generating unit includes the first mass flowmenter and ozone generator, and pure oxygen connects through the first mass flowmenter To ozone generator, that is, generate O3Gas.In the present invention is embodied as, the flow velocity of the first mass flowmenter is 10ml/min.
O3Signal generating unit and connecting tube cleaning unit adopt external diameter and connect for 1/8 inch of four fluorine tube.
Three-way solenoid valve is Two In and One Out type, and the first air admission hole of three-way solenoid valve is connected with ozone generator, second Air admission hole connects ambient air;The activated carbon tube of the outlet connection connecting tube cleaning unit of three-way solenoid valve.
2) sampling configuration or zero point pattern are arranged by three-way solenoid valve;In the light that zero point type collection real atmosphere is obtained Spectrum is used as reference spectra;In sampling configuration, high concentration O is injected in sampling process3, NO Jing are chemically converted into NO2, then survey Amount is converted into NO2Spectrum afterwards is used as sampling spectrum;
21) three-way solenoid valve connects the first air admission hole, closes the second air admission hole, and into zero point pattern, now connecting tube is clear The pumping flow velocity for washing unit is more than O3The gas feed flow rate of generator, the O of generation3Reaction warehouse, whole connected tube cleanings are not entered into Unit is taken away and is removed, and fractional-sample gas is taken away and removed also by connecting tube cleaning unit, and the gas of connecting tube is formed and Flow and clean the O remained in connecting tube3;Now NO2Used as reference spectra, reference spectra signal is included the spectrum of measuring instrument measurement The NO of itself in atmospheric environment2Absorb caused by absorption signal, other factors and scatter;
22) it is sampling configuration when three-way solenoid valve connects the second air admission hole, closes the first air admission hole, now O3Generator The O of generation3Through connecting tube, and sample gas mix into reaction warehouse;In reaction warehouse, the ozone of high concentration is by the complete oxygen of NO Turn to NO2, enter into NO2Measuring instrument is measured, and is controlled to be evacuated power respectively and is adopted by the first air pump and the second mass flowmenter Sample flow velocity, now measures the NO that the spectrum for obtaining is totally converted for sampling spectrum, spectral signal of sampling comprising air NO2Absorb letter Number, the NO of itself in atmospheric environment2Absorb caused by absorption signal, other factors and scatter;Now connecting tube cleaning unit is held It is continuous to pass through the second air admission hole suction ambient air, for keeping the location mode stable operation, and protect the second air pump.
In being embodied as, the second air pump coordinates the speed of evacuation of metering hole stable in 50-100ml/min to the present invention, the The flow velocity of two mass flowmenters is 2.0L/min;The volume of reaction warehouse is 30ml, it is ensured that the efficiency of NO titration is more than 99%.
In embodiments of the present invention, set three-way solenoid valve to realize being measured as sampling configuration and zero point mould by sequencing Formula automatically switches, and a sampling configuration and a zero point pattern are one cycle, such that it is able to realize sampling configuration and zero point mould Formula spectral signal interleaved acquisition.NO2The resolution ratio of measuring instrument is 1s, and circulation time is set to 1min, wherein front 10s is zero point mould Formula (collection reference spectra);Afterwards 50s is sampling configuration (collection sampling spectrum), and by high frequency switching reference spectra and sampling are ensured NO in spectrum2No change is absorbed and scatters with other.
3) reference spectra for being obtained using measurement and sampling spectroscopic data, measured chamber strengthens data processing method and obtains To the NO of conversion2Concentration (concentration of NO i.e. in air), is achieved in the on-line measurement of air NO concentration.
In embodiments of the present invention, specifically, the reference spectra (averaging) and sampling spectrum in each circulation is One unit pairing carries out the NO that the difference of data processing, reference spectra and sampling spectral signal is only converted into by NO2Inhale Receipts are caused, with the NO in air2Concentration is unrelated, also will not be by NO in air2Measurement interference be brought into the measurement of NO.Finally lead to Cross calculating absorption coefficient and NO is obtained using least square fitting2Concentration, i.e., the concentration of NO in air.
Compared with prior art, the invention has the beneficial effects as follows:
The present invention provides a kind of air NO concentration on-line measurement devices and measuring method, especially realizes NO in typical suburb Accurate measurement.At least including pure oxygen gas, the first mass flowmenter, ozone generator, connecting tube, sampling pipe, reaction warehouse, NO2Measuring instrument, the second mass flowmenter, the first air pump, three-way solenoid valve, activated carbon tube, metering hole and the second air pump.This NO is changed into NO by bright employing chemical conversion process2, NO in air is converted into using wideband cavity reinforced absorption spectrum technology NO2Carry out quantitatively, realizing the online accurate measurement of air NO concentration.The present invention program has low test limit, high sensitivity, height The characteristics of spatial and temporal resolution, high stability and low cost.
Advantages of the present invention includes following several respects:
(1) this part of NO that the present invention is converted into using cavity reinforced absorption spectrum technology as NO2Carry out quantitatively, With comprising atmospheric environment NO2Spectrum as reference spectra, rather than spectrum is made reference using traditional pure nitrogen gas spectrum, to wrap Containing being converted into NO2Measurement result afterwards as sampling spectrum, so as to realize the NO to NO transform portions2Accurate quantitative analysis, it is not necessary to survey NO in amount air2Concentration, it is not required that carry out NOx to NO2Subtractive, it is to avoid error propagation, it is to avoid atmospheric environment in measurement process In the NO of itself2Interference of the concentration to NO.
(2) present invention when zero point pattern is changed to sampling configuration using connecting tube cleaning unit to the O in connecting tube3 Quickly taken away and removed, realized being switched fast for two kinds of measurement patterns, transit time is short, ensured that data are complete as far as possible Property.
(3) present invention only with a set of cavity reinforced absorption spectrum equipment as NO2Measuring instrument, realizes to higher concentration NO2 The absolute measurement of the low NO under background, with very high resolution ratio and detection sensitivity.Improve the accuracy of detection of NO.
(4) present invention is single-point Sampling techniques, and stability height, low cost, operation and maintenance are simple.
Description of the drawings
Fig. 1 is a kind of structure for typical suburb air NO concentration on-line measurement devices provided in an embodiment of the present invention Figure;
Wherein, 1-pure oxygen;2-the first mass flowmenter;3-ozone generator;4-connecting tube;5-sampling pipe;6— Reaction warehouse;7—NO2Measuring instrument;8-the second mass flowmenter;9-the first air pump;10-three-way solenoid valve;11-the first air inlet Hole;12-the second air admission hole;13-activated carbon tube;14-metering hole;15-the second air pump.
Fig. 2 is the FB(flow block) of air NO concentration On-line Measuring Methods provided in an embodiment of the present invention.
Specific embodiment
Below in conjunction with the accompanying drawings, the present invention is further described by embodiment, but limits the model of the present invention never in any form Enclose.
The present invention provides a kind of air NO concentration on-line measurement devices and measuring method, at least including pure oxygen gas, first Mass flowmenter, ozone generator, connecting tube, sampling pipe, reaction warehouse, NO2Measuring instrument, the second mass flowmenter, the first air pump, Three-way solenoid valve, activated carbon tube, metering hole and the second air pump.NO is changed into NO by the present invention using chemical conversion process2, adopt NO in air is converted into NO with wideband cavity reinforced absorption spectrum technology2Carry out quantitatively, so as to realize air NO concentration Online accurately measurement.
, for typical suburb air, the air NO concentration on-line measurement devices of employing are as shown in figure 1, bag for the embodiment of the present invention Include:Pure oxygen 1, the first mass flowmenter 2, ozone generator 3, connecting tube 4, sampling pipe 5, reaction warehouse 6, NO2Measuring instrument 7, second Mass flowmenter 8, the first air pump 9, three-way solenoid valve 10, the first air admission hole 11, the second air admission hole 12, activated carbon tube 13, current limliting Hole 14, the second air pump 15.Wherein, pure oxygen 1 connects ozone generator 3 through the first mass flowmenter 2, so as to constitute O3Generate single Unit.The O of generation3Gas point two-way, the connecting tube cleaning unit for connecting all the way after a threeway, the unit is by an electromagnetism Triple valve 10, activated carbon tube 13, the air pump 15 of metering hole 14 and second are connected and composed with this;After another road connection sampling pipe 1 End, distinguishes coupled reaction storehouse 6, NO after sampling pipe 12Measuring instrument 7, the second mass flowmenter 8 and the first air pump 9.
The workflow and data acquisition of the present invention are illustrated below by a specific example.
The present invention is using cavity reinforced absorption spectrum technology as measuring instrument come to NO2Measure, and only need to what is adopted One NO2Measuring instrument (i.e. one measurement reaction chamber), NO2The light source that measuring instrument is adopted is high-capacity LED monochromatic light source, transmitting Light spectral centre wavelength be 460nm, energy of light source is concentrated mainly on 440-480nm.High reflective mirror piece reflectivity in chamber is big In 99.99%.In being embodied as, the flow velocity of the first mass flowmenter is 10ml/min to the present invention, and the second air pump coordinates current limliting The speed of evacuation in hole is stable in 100ml/min, and the flow velocity of the second mass flowmenter is 2.0L/min;O3Generating unit and connecting tube Cleaning unit adopts external diameter and connects for 1/8 inch of four fluorine tube;Sampling pipe adopts external diameter for 1/4 inch of four fluorine tube, is used in combination Reducing tee and connecting tube connect, and the volume of reaction warehouse is 30ml, it is ensured that the efficiency of NO titration is more than 99%.
During air NO concentration on-line measurement device busies, O is debugged3Signal generating unit, it is ensured that concentration after persistently output mixes The O of about 200ppm3;Debugging NO2Measuring instrument, it is ensured that light-source temperature is stable, demarcates emissivity.Electromagnetism three is set by sequencing Port valve automatically switches realizing being measured as sampling configuration and zero point pattern, and a sampling configuration and a zero point pattern are once to follow Ring, realizes sampling configuration and zero point pattern spectral signal interleaved acquisition.Instrumental resolution is 1s, and circulation time is set to 1min, Wherein front 10s is zero point pattern (collection reference spectra);Afterwards 50s is sampling configuration (collection sampling spectrum), is switched by high frequency Ensure NO in atmospheric environment2Absorb and scatter unchanged with others.During sampling configuration, O3Through connecting tube and sample gas meeting Reaction warehouse is mixed into, NO complete oxidations are NO by the ozone of high concentration in reaction warehouse2And enter into NO2Measuring instrument is surveyed Amount, obtains spectrum of sampling, the NO that spectral signal is totally converted comprising air NO2Absorption signal, the NO of itself in atmospheric environment2Inhale The collection of letters number, other absorptions and scattering.During zero point pattern, the pumping flow velocity of connecting tube cleaning unit is more than O3The supply of generator Flow velocity, flow velocity is the O of 10ml/min3Connected tube cleaning unit is taken away, while also 90ml/min sample gas form refluence And clean connecting tube.Now NO2The spectrum of measuring instrument measurement as reference spectra, spectral signal comprising in atmospheric environment itself NO2Absorption signal, other absorptions and scattering.
Based on reference spectra and sampling spectroscopic data, the reference spectra (averaging) and sampling spectrum in each circulation The NO that the difference of data processing, reference spectra and sampling spectral signal is only converted into by NO is carried out for a unit pairing2 Absorption is caused, and calculated absorption coefficient can obtain NO using least square fitting2Concentration, i.e., NO's is dense in air Degree.In the reflectivity R (λ) and effective cavity length d of known high reflectance eyeglass, absorption coefficient is calculated by formula 1 (λ):
Wherein I (λ) sampling spectrum, I0(λ) reference spectra, is that 440-480nm will by least square fitting method in wavelength Other Rayleigh scatterings, Mie scattering (can be fitted by three rank multinomials) and NO2Absorption cross-section pass through NO2Particle density intend Be bonded to absorption coefficient, so as to obtain air in NO concentration.
It should be noted that the purpose for publicizing and implementing example is help further understands the present invention, but the skill of this area Art personnel be appreciated that:In without departing from the present invention and spirit and scope of the appended claims, various substitutions and modifications are all It is possible.Therefore, the present invention should not be limited to embodiment disclosure of that, and the scope of protection of present invention is with claim The scope that book is defined is defined.

Claims (10)

1. in a kind of air NO concentration on-line measurement device, including ozone signal generating unit, connecting tube cleaning unit, sampling pipe, The NO of reaction warehouse, the second mass flowmenter, the first air pump and one based on cavity reinforced absorption spectrum technology2Measuring instrument;It is described smelly Oxygen signal generating unit includes pure oxygen gas, the first mass flowmenter and ozone generator, and pure oxygen gas is through the first mass flowmenter Connection ozone generator, generates ozone gas;The connecting tube cleaning unit includes three-way solenoid valve and the activity being sequentially connected Charcoal pipe, metering hole and the second air pump;The ozone gas of generation are divided into two-way, the first via and connecting tube cleaning unit phase through threeway Connection;Second tunnel connects the rear end of sampling pipe;The rear end of sampling pipe is sequentially connected reaction warehouse, NO2Measuring instrument, the second mass flow Meter and the first air pump;The on-line measurement device arranges sampling configuration or zero point pattern by the three-way solenoid valve, by institute State NO2Measuring instrument measures respectively the absorption spectrum strength signal of sampling configuration and zero point pattern, used as sampling spectrum and reference light Compose, then NO in air is obtained by spectrum simulation and be converted into NO2Concentration value, that is, realize that measurement obtains NO in atmospheric environment dense Degree.
2. on-line measurement device as claimed in claim 1, it is characterised in that:The NO2The light source that measuring instrument is adopted is for high power LED monochromatic light sources, the light spectral centre wavelength of light source transmitting is 460nm;The NO2In the measurement reaction chamber of measuring instrument High reflective mirror piece reflectivity is more than 99.99%.
3. on-line measurement device as claimed in claim 1, it is characterised in that:In the ozone signal generating unit, purity oxygen is through One mass flowmenter precise control flow velocity, with low discharge ozone generator is entered, and UV illumination light is received in ozone generator Solution generates the ozone gas of steady concentration, and NO is fully oxidized into NO in the concentration level short time of the ozone gas2
4. on-line measurement device as claimed in claim 1, it is characterised in that:In the connecting tube cleaning unit, three-way solenoid valve For Two In and One Out type three-way solenoid valve;First air admission hole of three-way solenoid valve is connected with ozone generator;Second air admission hole connects Logical ambient air;The activated carbon tube of the outlet connection connecting tube cleaning unit of three-way solenoid valve;Second air pump is opened all the time and led to Cross metering hole coutroi velocity.
5. on-line measurement device as claimed in claim 1, it is characterised in that:The setting flow of first mass flowmenter is much Less than the flow of the second mass flowmenter so that the gas feed flow rate of ozone signal generating unit is far smaller than the flow velocity of sample gas;It is excellent Selection of land, the second air pump coordinates the speed of evacuation of metering hole stable in 50-100ml/min, and the flow velocity of the second mass flowmenter is 2.0L/min。
6. on-line measurement device as claimed in claim 1, it is characterised in that:Ozone generating unit and connecting tube cleaning unit are adopted It is connected with the four fluorine tube that external diameter is 1/8 inch.
7. on-line measurement device as claimed in claim 1, it is characterised in that:The volume of the reaction warehouse and sampling flow velocity and ozone The concentration of ozone gas that generating unit is generated matches;Preferably, the volume of the reaction warehouse is 30ml so that the effect of NO titration Rate is more than 99%.
8. on-line measurement device as claimed in claim 1, it is characterised in that:It is automatically opened or closed by sequencing setting described Three-way solenoid valve is realizing high frequency switch sampling pattern and zero point pattern so that the atmospheric environment in reference spectra and sampling spectrum Middle NO2It is constant with the absorption of other gases.
9. in a kind of air NO concentration On-line Measuring Method, sampling configuration or zero point pattern are arranged by three-way solenoid valve, Air NO is completely converted into NO by generating ozone gas during sampling configuration2, then by a NO2Measuring instrument is measured respectively Obtain the signal of the absorption spectrum intensity of sampling configuration and zero point pattern, then NO in air obtained by spectrum simulation being converted into NO2Concentration value, thus obtain the NO concentration in air;Specifically include following steps:
1) arranging ozone signal generating unit is used to generate high-concentrated ozone gas;In the ozone signal generating unit after a threeway Two-way, the first via is divided to be connected with connecting tube cleaning unit, the connecting tube cleaning unit includes the electromagnetic three-way being sequentially connected Valve, activated carbon tube, metering hole and the second air pump;Second tunnel connects the rear end of sampling pipe, and the rear end of sampling pipe is sequentially connected again instead Ying Cang, NO2Measuring instrument, the second mass flowmenter and the first air pump;
2) sampling configuration or zero point pattern are arranged by three-way solenoid valve;The spectrum obtained in zero point type collection real atmosphere is made For reference spectra;In sampling configuration, the implantation step 1 in sampling process) the high-concentrated ozone gas, NO Jing chemistry is turned Turn to NO2, then measure and be converted into NO2Spectrum afterwards is used as sampling spectrum;Including:
21) when three-way solenoid valve enters zero point pattern, the pumping flow velocity of the connecting tube cleaning unit generates list more than ozone The ozone gas of generation are all taken away and are removed by the gas feed flow rate of unit, the connecting tube cleaning unit, fractional-sample gas Take away and remove by connecting tube cleaning unit, the gas of connecting tube is formed and flows backwards and clean the ozone remained in connecting tube;This When will be by NO2Used as reference spectra, the reference spectra signal is included in atmospheric environment certainly the spectrum that measuring instrument measurement is obtained The NO of body2Absorb caused by absorption signal, other factors and scatter;
22) when three-way solenoid valve is sampling configuration, the ozone that ozone signal generating unit is produced is through connecting tube, and sampled pipe Sample gas mix into reaction warehouse;In reaction warehouse, NO complete oxidations are NO by the ozone of high concentration2, enter into NO2Measurement Instrument is measured, and is controlled respectively to be evacuated power and sampling flow velocity by the first air pump and the second mass flowmenter, and now measurement is obtained The NO that is totally converted comprising air NO for sampling spectrum, spectral signal of sampling of spectrum2In absorption signal, atmospheric environment itself Absorb caused by NO2 absorption signals, other factors and scatter;
3) using step 2) reference spectra and sampling spectroscopic data for obtaining is measured, transit chamber strengthens data processing method and processes To the NO of conversion2The concentration of NO in concentration, as air, is achieved in the on-line measurement of air NO concentration.
10. On-line Measuring Method as claimed in claim 9, is characterized in that, the NO2The light source that measuring instrument is adopted is for high-capacity LED Monochromatic light source, the light spectral centre wavelength of transmitting is 460nm, and the high reflective mirror piece reflectivity measured in reaction chamber is more than 99.99%;The ozone signal generating unit includes the first mass flowmenter and ozone generator, and pure oxygen is through the first mass flow Meter is connected to ozone generator, that is, generate ozone gas;The ozone signal generating unit and connecting tube cleaning unit adopt external diameter Connect for 1/8 inch of four fluorine tube;The three-way solenoid valve is Two In and One Out type, the first air admission hole of three-way solenoid valve and ozone Generator is connected, the second air admission hole connection ambient air, the activated carbon tube of outlet connection connecting tube cleaning unit;When the electricity When magnetic triple valve is sampling configuration, the connecting tube cleaning unit continues through the second air admission hole suction ambient air, for protecting The location mode stable operation is held, and protects the second air pump;The chamber strengthens data processing method especially by absorption is calculated Number simultaneously obtains NO using least square fitting2Concentration, the concentration of NO as in air.
CN201611261453.5A 2016-12-30 2016-12-30 Online measurement device and measurement method for NO concentration in high-NO2 and low-NO atmosphere Pending CN106644986A (en)

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