CN113376158A - System and method for online measurement of ozone generation rate and ozone generation sensitivity - Google Patents

System and method for online measurement of ozone generation rate and ozone generation sensitivity Download PDF

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CN113376158A
CN113376158A CN202110671996.9A CN202110671996A CN113376158A CN 113376158 A CN113376158 A CN 113376158A CN 202110671996 A CN202110671996 A CN 202110671996A CN 113376158 A CN113376158 A CN 113376158A
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ozone generation
electromagnetic valve
way electromagnetic
mass flow
reaction
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周俊
吴艳峰
袁斌
邵敏
覃广志
郝怡忻
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Jinan University
University of Jinan
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Jinan University
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    • G—PHYSICS
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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Abstract

The invention discloses a system and a method for online measuring ozone generation rate and ozone generation sensitivity, wherein the system comprises: the air input end is respectively connected with the reaction cavity and the reference cavity through the particulate filter, the reaction cavity is respectively connected with the NO reaction tube and the second mass flow controller through the first three-way electromagnetic valve, the reference cavity is respectively connected with the NO reaction tube and the second mass flow controller through the second three-way electromagnetic valve, the second mass flow controller is connected with the discharge port, and the NO reaction tube is connected with the CAPS NO reaction tube2The detector is connected, the first NO standard gas input end is connected with the FeSO4The invention alternately measures the ozone generated by the photochemical reaction without light, and has the advantages of high accuracy, low detection limit, low cost, simple structure, low cost, and the like,The stability is good.

Description

System and method for online measurement of ozone generation rate and ozone generation sensitivity
Technical Field
The invention relates to the technical field of ozone detection, in particular to a system and a method for measuring the ozone generation rate and the ozone generation sensitivity on line.
Background
The ozone on the surface of the convection layer is formed by precursor Volatile Organic Compounds (VOCs) and nitrogen oxides (NOx ═ NO + NO)2) The secondary pollutants generated by photochemical reaction, ozone generation and precursor VOCs and NOx thereof are in a nonlinear relation, effective ozone prevention and control can be realized by controlling the discharge of the ozone precursor, and accurate judgment on the ozone generation sensitivity is needed. Therefore, the research on the generation rate of ozone in the ambient atmosphere and the sensitivity of the ozone to precursors has great urgent needs on cleaning the evolution mechanism of ozone generation and pollution prevention and control measures.
The current research on the ozone generation rate and the ozone generation sensitivity mainly uses model simulation means, and is divided into two main categories of emission-based modeling and observation-based modeling. However, model simulation requires meteorological parameters, emission lists, observation data and the like, has great uncertainty, and cannot effectively monitor the ozone generation sensitivity in real time. Therefore, the current research work on ozone pollution needs a detection technology that can effectively quantify the ozone generation rate and the ozone generation sensitivity.
Disclosure of Invention
In order to overcome the defects and shortcomings of the prior art, the invention provides a system for measuring the ozone generation rate and the ozone generation sensitivity on line, the system can directly measure the ozone generation rate and the ozone generation sensitivity on line, and can realize the comparison of a direct measurement result and a model simulation result to correct model errors, thereby achieving the purpose of comprehensively understanding the formation mechanism of ozone pollution and providing effective theoretical support for prevention and control of the ozone pollution; the ozone generating speed and the ozone generating sensitivity in the atmospheric environment under different pollution conditions can be accurately and quickly obtained, so that different types of testing and researching requirements can be met.
In order to achieve the purpose, the invention adopts the following technical scheme:
the invention provides a system for on-line measuring ozone generation rate and ozone generation sensitivity, comprising: the device comprises an ambient air input end, a particulate filter, a reaction cavity, a reference cavity, a first three-way electromagnetic valve, a second three-way electromagnetic valve, a first mass flow controller, a second mass flow controller, a discharge port, a first NO standard gas input end, FeSO4Reduction tube, NO reaction tube, CAPS NO2The detector, a second NO standard gas input end, a VOCs standard gas input end, a third mass flow controller and a fourth mass flow controller;
the first three-way electromagnetic valve is provided with a first three-way electromagnetic valve input port, a first three-way electromagnetic valve first channel outlet and a first three-way electromagnetic valve second channel outlet;
the second three-way electromagnetic valve is provided with a second three-way electromagnetic valve input port, a second three-way electromagnetic valve first channel outlet and a second three-way electromagnetic valve second channel outlet;
the environment air input end is connected with the particulate matter filter input end, the particulate matter filter output end is connected with the input of reaction chamber, reference chamber respectively, the output and the first three-way solenoid valve input port of reaction chamber are connected, the export of the first passageway of first three-way solenoid valve is connected with NO reaction tube input, the output and the CAPS NO reaction tube of NO reaction tube2The detector is connected, the outlet of a second channel of the first three-way electromagnetic valve is connected with the input end of a second mass flow controller, and the output end of the second mass flow controller is connected with the discharge port;
the output end of the reference cavity is connected with the input port of a second three-way electromagnetic valve, the outlet of a first channel of the second three-way electromagnetic valve is connected with the input end of the NO reaction tube, and the outlet of a second channel of the second three-way electromagnetic valve is connected with the input end of a second mass flow controller;
the first NO standard gas input end and the FeSO4The input end of the reduction tube is connected, and the FeSO4The output end of the reduction tube is connected with the input end of a first mass flow controller, and the output end of the first mass flow controller is connected with the input end of the NO reaction tubeConnecting;
the input end of the second NO standard gas is connected with the input end of a third mass flow controller, and the output end of the third mass flow controller is respectively connected with the input ends of the reaction cavity and the reference cavity;
the VOCs standard gas input end is connected with the input end of a fourth mass flow controller, and the output end of the fourth mass flow controller is connected with the input ends of the reaction cavity and the reference cavity respectively.
As a preferable technical scheme, a bypass is further arranged, the input end of the bypass is connected with the ambient air input end, and the output end of the bypass is respectively connected with the input ends of the reaction cavity and the reference cavity.
According to the preferable technical scheme, the reaction cavity and the reference cavity are both made of quartz tube materials, the outer wall of the reference cavity is covered with a shading material, and the shading material is used for shading ultraviolet rays.
As a preferred technical scheme, the synchronous switching device of the three-way electromagnetic valve is also arranged and used for synchronously switching a first three-way electromagnetic valve and a second three-way electromagnetic valve, wherein the outlet of a first channel of the first three-way electromagnetic valve is opened, the outlet of a second channel of the first three-way electromagnetic valve is closed, the outlet of a first channel of the second three-way electromagnetic valve is closed, and the outlet of a second channel of the second three-way electromagnetic valve is opened;
the outlet of the first channel of the second three-way electromagnetic valve is opened, and the outlet of the second channel of the second three-way electromagnetic valve is closed; and the outlet of the first channel of the first three-way electromagnetic valve is closed, and the outlet of the second channel of the first three-way electromagnetic valve is opened.
The invention also provides a method for measuring the ozone generation rate and the ozone generation sensitivity on line, which is provided with the system for measuring the ozone generation rate and the ozone generation sensitivity on line and comprises the following steps:
ozone generation rate measurements were performed: the method comprises the following steps that ambient atmosphere passes through a particulate filter, gas is simultaneously introduced into a reaction cavity and a reference cavity at the same speed, and a first measurement mode and a second measurement mode are set;
a first measurement mode: the air in the reaction chamber passes through the first tee joint after being irradiated by sunlightThe outlet of the first channel of the electromagnetic valve enters the NO reaction tube, and the gas passes through the FeSO4The reduction tube reacts with NO standard gas input by the first mass flow controller, so that ozone generated by photochemical reaction and ozone originally contained in air are reduced into NO by NO2，CAPS NO2The detector carries out quantitative detection;
the air flowing through the reference cavity passes through a second channel outlet of the second three-way electromagnetic valve and a second mass flow controller and then is discharged from a discharge port;
the second measurement mode is as follows: air flowing through the reference cavity passes through the outlet of the first channel of the second three-way electromagnetic valve and then is input into the NO reaction tube, and the air pass through the FeSO4The reduction tube reacts with NO standard gas of the first mass flow controller, so that ozone originally contained in the air is reduced into NO2，CAPS NO2The detector carries out quantitative detection;
air in the reaction chamber is introduced into the second mass flow controller through the second channel outlet of the first three-way electromagnetic valve and then is discharged from the discharge port;
setting time interval to switch between the first measurement mode and the second measurement mode, and measuring NO in the reaction chamber and the reference chamber after the gas passes through the NO reaction tube2And calculating the apparent generation rate of ozone by combining the average residence time of the gas in the reaction cavity and the reference cavity.
As a preferred technical solution, the calculation to obtain the apparent generation rate of ozone has a specific calculation formula:
Figure BDA0003119070720000041
wherein [ NO ]2]ambAnd [ NO2]refRespectively representing CAPS NO in the first measurement mode and the second measurement mode2Total NO detected by the detector2Concentration; [ NO ]2]τ，ambAnd [ NO2]τ，refRespectively representing NO when the ambient atmosphere passes through the reaction chamber and the reference chamber in the first measurement mode and the second measurement mode2Concentration of [ O ]3]τ，ambAnd [ O3]τ，refRespectively showing the conversion of ambient atmosphere into NO when the ambient atmosphere passes through the NO reaction tube in the first measurement mode and the second measurement mode2O of (A) to (B)3Concentration, C represents the conversion efficiency, and τ represents the average residence time of ambient atmosphere as it passes through the reaction chamber and the reference chamber.
As a preferable technical scheme, the method further comprises an ozone generation sensitive area judging step, and specifically comprises the following steps:
and independently introducing the NO standard gas or the VOCs standard gas into the reaction cavity at the ozone generation rate step by step, detecting the nonlinear response relation between the ozone generation rate and the NO standard gas or the VOCs standard gas, and judging that the ozone in the ambient atmosphere is generated into a NOx sensitive area, a VOCs sensitive area or a transition area.
As a preferable technical scheme, the method further comprises the detection of the ozone generation sensitivity of the particulate matters, the system for online measurement of the ozone generation rate and the ozone generation sensitivity is provided with a bypass, and the introduced ambient atmosphere passes through the bypass and is compared with the ozone generation sensitivity measured when the particulate matters are introduced into the particulate matter filter in the ozone generation sensitivity area determination step, so that the influence result of the particulate matters on the ozone generation sensitivity is obtained.
As a preferred technical scheme, the method also comprises a characterization step, wherein the characterization content comprises the average residence time of reactants in each reaction cavity, the wall loss of Ox and the O in the NO reaction cavity3Conversion to NO2The conversion efficiency of (a).
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) the invention converts ozone into NO2And using the detection NO2Accurate and rapid NO detection by using optical cavity attenuation phase change technology (CAPS)2The output concentration of the gas avoids the detection of NO by the traditional method2Imprecise, thereby accurately quantifying the ozone concentration.
(2) The invention adopts the three-way valve to carry out double-channel measurement, alternately measures the ozone generated by the photochemical reaction without interference factors, and has the advantages of high accuracy, low detection limit and good stability.
(3) The method directly measures the ozone generation rate and the ozone generation sensitivity on line, has the advantages of high accuracy and good timeliness compared with the traditional model simulation judgment method, can provide direct and effective measure guidance for ozone pollution prevention and treatment according to the detection result, and can meet different types of test and research requirements.
(4) The invention adopts the technical scheme of automatically switching different measurement modes, realizes the simultaneous online measurement of the ozone generation rate, the ozone generation sensitivity and the influence of particles on the ozone generation sensitivity, solves the technical problem that the ozone generation sensitivity cannot be measured at present, and achieves the effect of directly measuring the ozone generation sensitivity.
Drawings
FIG. 1 is a schematic diagram showing the construction of a system for online measurement of ozone generation rate and ozone generation sensitivity according to this embodiment.
The device comprises a 1-ambient air input end, a 2-particulate filter, a 3-reaction chamber, a 4-reference chamber, a 5-first three-way electromagnetic valve, a 6-second three-way electromagnetic valve, a 7-first mass flow controller, an 8-second mass flow controller, a 9-discharge port, a 10-first NO standard gas input end, and a 11-FeSO4Reduction tube, 12-NO reaction tube, 13-CAPS NO2The device comprises a detector, 14-a second NO standard gas input end, 15-VOCs standard gas input end, 16-a third mass flow controller and 17-a fourth mass flow controller.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Examples
As shown in fig. 1, the present embodiment provides a system for online measurement of ozone generation rate and ozone generation sensitivity, comprising: the device comprises an ambient air input end 1, a particulate filter 2, a reaction chamber 3, a reference chamber 4, a first three-way electromagnetic valve 5, a second three-way electromagnetic valve 6, a first mass flow controller 7, a second mass flow controller 8, a discharge port 9, a first NO standard gas input end 10, FeSO4 Reduction tube 11, NO reaction tube 12, CAPS NO2A detector 13, a second NO standard gas input end 14, a VOCs standard gas input end 15, a third mass flow controller 16 and a fourth mass flow controller 17;
the first three-way electromagnetic valve 5 is provided with a first three-way electromagnetic valve input port, a first three-way electromagnetic valve first channel outlet and a first three-way electromagnetic valve second channel outlet;
the second three-way electromagnetic valve 6 is provided with a second three-way electromagnetic valve input port, a second three-way electromagnetic valve first channel outlet and a second three-way electromagnetic valve second channel outlet;
ambient air input 1 is divided into two the tunnel, and the main road is connected with particulate matter filter 2 inputs, and particulate matter filter 2 outputs are connected with reaction chamber 3, the input of reference chamber 4, and the bypass does not pass through particulate matter filter, and direct and reaction chamber 3, the input of reference chamber 4 are connected, and this embodiment sets up the bypass that does not pass through particulate matter filter is in order to detect the influence to ozone generation under the particulate matter condition to judge the importance of particulate matter to ozone generation.
The output end of the reaction cavity 3 is connected with the input port of a first three-way electromagnetic valve, the outlet of a first channel of the first three-way electromagnetic valve is connected with the input end of a NO reaction tube 12, and the output end of the NO reaction tube 12 is connected with CAPS NO2The detector 13 is connected, the first NO standard gas input end 10 is connected with FeSO4The input end of the reduction tube 11 is connected with FeSO4The output end of the reduction tube 11 is connected with the input end of the first mass flow controller 7, the output end of the first mass flow controller 7 is connected with the input end of the NO reaction tube 12, the first NO standard gas input end 10 is used for providing reducing gas NO, and FeSO4The function of the reduction tube 11 is to maintain the reducibility of NO and to prevent NO from being oxidized into NO2. The outlet of the second channel of the first three-way electromagnetic valve is connected with the input end of a second mass flow controller 8, and the output end of the second mass flow controller 8 is connected with a discharge port 9;
the output end of the reference cavity 4 is connected with the input port of a second three-way electromagnetic valve, the outlet of a first channel of the second three-way electromagnetic valve is connected with the input end of the NO reaction tube 12, and the outlet of a second channel of the second three-way electromagnetic valve is connected with the input end of a second mass flow controller 8;
when measuring the generation of ozone in the reaction cavity, the third mass flow controller 16 controls the flow rate of the second NO standard gas input end 14 to be 0; the fourth mass flow controller 17 controls the flow rate of the VOCs standard gas input end 15 to be 0, the first channel outlet of the first three-way electromagnetic valve is opened, the second channel outlet of the first three-way electromagnetic valve is closed, the first channel outlet of the second three-way electromagnetic valve is closed, and the second channel outlet of the second three-way electromagnetic valve is opened;
when measuring reference chamber ozone generation, the third mass flow controller 16 controls the flow rate of the second NO standard gas input end 14 to be 0; the fourth mass flow controller 17 controls the flow rate of the VOCs standard gas input end 15 to be 0, the outlet of the first channel of the second three-way electromagnetic valve is opened, and the outlet of the second channel of the second three-way electromagnetic valve is closed; the outlet of the first channel of the first three-way electromagnetic valve is closed, and the outlet of the second channel of the first three-way electromagnetic valve is opened.
The method mainly comprises the following steps: (a) an ozone generation rate detecting section and (b) an ozone generation sensitivity detecting section, wherein (a) the ozone generation rate detecting section is realized by: the ambient atmosphere 1 first passes through a particulate filter 2, the remaining gas portion being at the same rate (-0.85L min)-1) Simultaneously introducing into a reaction chamber 3 and a reference chamber 4 which are made of quartz tubes and have the same size for 0.85L min-1The total flow rate of the single chamber is set according to the sampling flow rate of CAPS, the bypass is not communicated at the moment, the gas does not pass through the bypass but passes through the particulate filter and then enters the reaction chamber and the reference chamber, and the rest gas is the gas left after the particulate is removed; the reaction cavity 3 is directly exposed to ultraviolet light, and simulates the reaction generated by ozone under the condition of sunlight illumination in daytime when the reaction cavity is introduced into the ambient atmosphere, the reference cavity and the reaction cavity are both made of quartz materials, the size, the shape and the like of the reference cavity and the reaction cavity are completely the same, and the outer wall of the reference cavity 4 is covered with a shading material to shade ultraviolet rays, so that the reference cavity can be used as a reference cavity without photochemical reaction. The output end of the reaction cavity 3 is connected with a first three-way electromagnetic valve 5, and the output end of the reference cavity 4 is connected with a second three-way electromagnetic valve 6;
according to the reaction characteristics of the whole system, the working state of the system is divided into two modes. The method comprises the following specific steps:
a first measurement mode: after the air in the reaction chamber 3 is irradiated by sunlight, the air is irradiated for 0.84L min-1The flow rate of the gas directly enters the NO reaction tube 12 through the outlet of the first channel of the first three-way electromagnetic valve. Thereafter, the gas is passed through FeSO4NO standard gas (flow rate 0.01L min) input by the reduction pipe 11 and the first mass flow controller 7-1) The reaction is carried out so that the ozone generated by the photochemical reaction and the ozone originally contained in the air are both reduced to NO by NO2Thereby being CAPS NO2The detector 13 further quantifies. At the same time, the air flowing through the reference chamber 4 takes 0.84L min-1The flow rate of the gas passes through a second three-way electromagnetic valve 6, passes through a second channel outlet, and is directly discharged from a discharge port 9 after passing through a second mass flow controller 8. Here 0.84L min-1Considering that the flow rate of the first NO standard gas 1 is 0.01L min-1The total flow rate after the NO and the gas flow rate in the chamber were merged was still 0.85L min-1。
The second measurement mode is as follows: air flow through reference chamber 4 was 0.84L min-1Is directly introduced into the NO reaction tube 12 through the first passage outlet after passing through the second three-way solenoid valve 6, and the gas passes through the FeSO4NO standard gas (flow rate 0.01L min) of reduction pipe 11 and first mass flow controller 7-1) The reaction is carried out so that the ozone originally contained in the air is reduced to NO2Further using CAPS NO2Detector 13 for quantifying NO2And (4) concentration. At the same time, the air in the reaction chamber 3 is introduced into the second mass flow controller 8 through the second passage outlet of the first three-way solenoid valve 5 and is directly discharged from the discharge port 9.
This embodiment introduces ambient air into the device, first filtering out aerosols through the particulate filter 2. The flow rates of the gas flows through the reaction chamber 3 and the reference chamber 4 were both 0.84L min-1And ensuring that the conditions of the reaction chamber 3 and the reference chamber 4 are consistent except for the illumination, and then switching the states of the whole device according to the first measurement mode and the second measurement mode in sequence at intervals of 2min, and measuring Ox (═ O) in the reaction chamber 3 and the reference chamber 43+NO2) The difference value is obtained by calculation by combining the average residence time t of the gas in the reaction cavityApparent rate of ozone generation (P (ox)).
CAPS NO in ozone generation rate detector2Total NO detected by the detector 132Concentration [ NO ]2]Calculated using the following equation:
[NO2]＝[NO2]τ+C[O3]τ (1)
wherein [ NO ]2]τRepresenting NO at the outlet of the reaction chamber 3 with photochemical reaction (in the first measurement mode) or of the reference chamber 4 without photochemical reaction (in the second measurement mode)2Concentration, [ NO ] calculated in both cases using equation (1)2]Respectively with [ NO ]2]ambAnd [ NO2]refRepresents; c represents O in NO reaction tube 123Conversion to NO2The conversion efficiency of (a); τ is the average residence time of the ambient atmosphere as it passes through the reaction chamber 3 and the reference chamber 4. Thus calculated [ NO2]Is NO converted from ozone in the system in the first measurement mode or the second measurement mode2And native NO in the environment2So that [ Ox ] can be used](＝[NO2]+[O3]) It is shown that the ozone generation rate detected by the ozone generation rate detector is calculated by the following formula:
Figure BDA0003119070720000091
in the formula [ NO ]2]τ，ambAnd [ NO2]τ，refRespectively representing NO when the ambient atmosphere passes through the reaction chamber and the reference chamber in the first measurement mode and the second measurement mode2Concentration of [ O ]3]τ，ambAnd [ O3]τ，refRespectively showing the conversion of ambient atmosphere into NO when the ambient atmosphere passes through the NO reaction tube in the first measurement mode and the second measurement mode2O of (A) to (B)3Concentration;
(b) operation steps of the ozone generation sensitivity detecting section:
as shown in fig. 1, the improvement is made on the basis of (a) the ozone generation rate detection section, and an NO input device and a VOCs input device are added in a dashed box, wherein the NO input device comprises a second NO standard gas input end 14 and a third mass flow controller 16 for controlling the input flow rate of the NO standard gas, and the VOCs input device comprises a VOCs standard gas input end 15 and a fourth mass flow controller 17 for controlling the input flow rate of the VOCs standard gas;
when (a) the ozone generation rate detecting part is normally operated, NO or VOCs are artificially introduced into the reaction chamber 3 and the reaction reference chamber 4 at the same rate through the improved device part, and the ozone generation sensitivity region is judged by observing the change rule of the ozone generation rate.
In this embodiment, NO or VOCs are separately introduced into the reaction chamber with the ozone generation rate step by step and the nonlinear response relationship between the ozone generation rate and NO or VOCs is detected, and this nonlinear corresponding relationship can be plotted as an EKMA (empirical Kinetic Modeling approach) curve, so as to determine the ozone generation sensitivity according to the EKMA curve, and the method is as follows: in the process of measuring the ozone generation rate, NO or VOCs is separately introduced into the reaction cavity 3 and the reference cavity 4 step by step, and the introduction rates of the NO or the VOCs and the VOCs are adjusted through a mass flow controller, for example, firstly, under the condition that only VOCs are introduced, the flow rate of the VOCs is changed (from 0L/min to 0.5L/min, and 0.1L/min is increased every two minutes), and the ozone generation rate is observed; then, in the case of only introducing NO, the NO flow rate was increased by 0.1L/min every two minutes from 0L/min to 0.5L/min, and the ozone generation rate was observed. If P (O)3) Decreasing with decreasing NO feed rate, independent of changes with the feed rate of VOCs, indicates ozone generation in the ambient atmosphere to be a NOx sensitive zone; if P (O)3) Increasing with decreasing NO feed rate and decreasing with decreasing VOCs feed rate indicates ozone generation in the ambient atmosphere as a VOCs sensitive zone. If P (O)3) With NO and VOCs feed rates that do not vary significantly, ozone generation in the environment may be considered to be in the transition region. Based on the judgment, the purpose of making effective judgment on the main factors influencing the ozone generation can be achieved.
In order to detect the sensitivity of the particulate matter to ozone generation, in the present embodiment, during the operation of the ozone generation sensitivity detecting section (b), a mode is set such that the introduced ambient atmosphere passes through the bypass By pass without passing through the particulate matter filter 2, and is compared with the ozone generation sensitivity detected when the ozone generation sensitivity detecting section (b) is introduced into the particulate matter filter (the operation of the other sections of the process is the same as that of the step (b)), thereby obtaining the influence of the particulate matter on the ozone generation sensitivity.
In this embodiment, the built-up system for online measurement of ozone generation rate and ozone generation sensitivity is also characterized before being put into operation (characterization). The characterization contents mainly include the average residence time of reactants in each reaction chamber, the wall loss of Ox, and O in NO reaction chamber3Conversion to NO2The conversion efficiency of (c), etc. The specific characterization method is as follows:
1. average residence time τ: according to the fact that the sizes of the reaction cavity and the reference cavity are completely the same and are 17.85L, and the flow rate of gas flowing through the cavity is 0.85L/min, the average residence time of the gas in the cavity is 21min theoretically, NO with a certain concentration is introduced into the reaction cavity in a characterization experiment, and O is introduced synchronously3Conversion of NO into NO2Then observing the gas introduction until the detection of NO consistent with the concentration of NO introduced by CAPS2The average residence time is defined as time of (1).
2. Wall loss of Ox to convert a certain concentration of NO2And ozone standard gas is introduced into the reaction chamber at a flow rate of 0.85L/min, and the instrument is started to perform normal (a) operation of the ozone generation rate detection part, CAPS NO2The detector detects NO at the outlet2Concentration by comparison of NO at the inlet2And total concentration of ozone and NO at the outlet2Concentration difference, the wall loss of Ox (WL%) can be calculated:
Figure BDA0003119070720000111
wherein [ NO ]2]1And [ NO2]2Respectively represent NO entering the reaction chamber2Concentration and CAPS NO2NO measured by the detector2And (4) concentration. [ O ]3]Represents O entering the reaction chamber3And (4) concentration.
3、O3Conversion to NO2The conversion efficiency of (c): introducing standard ozone gas with concentration of 0-150ppb into the reaction chamber at flow rate of 0.85L/min, and starting the instrument to perform normal operation (a) on the ozone generation rate detection part, CAPS NO2Different concentrations of [ NO ] detected by the detector2]CAPSAnd different ozone concentration [ O ] introduced into the reaction chamber3]injectionThe ratio of (A) to (B) is O3Conversion to NO2The conversion efficiency of (c):
Figure BDA0003119070720000112
the above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.

Claims (9)

1. A system for online measurement of ozone generation rate and ozone generation susceptibility, comprising: the device comprises an ambient air input end, a particulate filter, a reaction cavity, a reference cavity, a first three-way electromagnetic valve, a second three-way electromagnetic valve, a first mass flow controller, a second mass flow controller, a discharge port, a first NO standard gas input end, FeSO4Reduction tube, NO reaction tube, CAPS NO2The detector, a second NO standard gas input end, a VOCs standard gas input end, a third mass flow controller and a fourth mass flow controller;
the first three-way electromagnetic valve is provided with a first three-way electromagnetic valve input port, a first three-way electromagnetic valve first channel outlet and a first three-way electromagnetic valve second channel outlet;
the second three-way electromagnetic valve is provided with a second three-way electromagnetic valve input port, a second three-way electromagnetic valve first channel outlet and a second three-way electromagnetic valve second channel outlet;
the environment air input end is connected with the particulate matter filter input end, the particulate matter filter output end is connected with the input of reaction chamber, reference chamber respectively, the output and the first three-way solenoid valve input port of reaction chamber are connected, the export of the first passageway of first three-way solenoid valve is connected with NO reaction tube input, the output and the CAPS NO reaction tube of NO reaction tube2The detector is connected, the outlet of a second channel of the first three-way electromagnetic valve is connected with the input end of a second mass flow controller, and the output end of the second mass flow controller is connected with the discharge port;
the output end of the reference cavity is connected with the input port of a second three-way electromagnetic valve, the outlet of a first channel of the second three-way electromagnetic valve is connected with the input end of the NO reaction tube, and the outlet of a second channel of the second three-way electromagnetic valve is connected with the input end of a second mass flow controller;
the first NO standard gas input end and the FeSO4The input end of the reduction tube is connected, and the FeSO4The output end of the reduction tube is connected with the input end of a first mass flow controller, and the output end of the first mass flow controller is connected with the input end of the NO reaction tube;
the input end of the second NO standard gas is connected with the input end of a third mass flow controller, and the output end of the third mass flow controller is respectively connected with the input ends of the reaction cavity and the reference cavity;
the VOCs standard gas input end is connected with the input end of a fourth mass flow controller, and the output end of the fourth mass flow controller is connected with the input ends of the reaction cavity and the reference cavity respectively.
2. The system for on-line measurement of ozone generation rate and sensitivity of claim 1 further comprising a bypass, wherein the input of the bypass is connected to the ambient air input, and the output of the bypass is connected to the input of the reaction chamber and the reference chamber respectively.
3. The system for on-line measurement of ozone generation rate and sensitivity according to claim 1, wherein the reaction chamber and the reference chamber are made of quartz tube material, and the outer wall of the reference chamber is covered with a light shielding material for shielding ultraviolet rays.
4. The system for on-line measurement of ozone generation rate and ozone generation sensitivity according to claim 1, further comprising a three-way solenoid valve synchronous switching device for synchronously switching a first three-way solenoid valve, which has a first passage outlet open, a second passage outlet closed, a first passage outlet closed, and a second three-way solenoid valve, which has a second passage outlet open;
the outlet of the first channel of the second three-way electromagnetic valve is opened, and the outlet of the second channel of the second three-way electromagnetic valve is closed; and the outlet of the first channel of the first three-way electromagnetic valve is closed, and the outlet of the second channel of the first three-way electromagnetic valve is opened.
5. A method for on-line measuring ozone generation rate and ozone generation sensitivity, characterized in that a system for on-line measuring ozone generation rate and ozone generation sensitivity according to any one of claims 1 to 4 is provided, comprising the steps of:
ozone generation rate measurements were performed: the method comprises the following steps that ambient atmosphere passes through a particulate filter, gas is simultaneously introduced into a reaction cavity and a reference cavity at the same speed, and a first measurement mode and a second measurement mode are set;
a first measurement mode: after the air in the reaction chamber is irradiated by sunlight, the air enters the NO reaction tube through the outlet of the first channel of the first three-way electromagnetic valve, and the air pass through the FeSO4The reduction tube reacts with NO standard gas input by the first mass flow controller, so that ozone generated by photochemical reaction and ozone originally contained in air are reduced into NO by NO2，CAPS NO2The detector carries out quantitative detection;
the air flowing through the reference cavity passes through a second channel outlet of the second three-way electromagnetic valve and a second mass flow controller and then is discharged from a discharge port;
second measurementMode (2): air flowing through the reference cavity passes through the outlet of the first channel of the second three-way electromagnetic valve and then is input into the NO reaction tube, and the air pass through the FeSO4The reduction tube reacts with NO standard gas of the first mass flow controller, so that ozone originally contained in the air is reduced into NO2，CAPS NO2The detector carries out quantitative detection;
air in the reaction chamber is introduced into the second mass flow controller through the second channel outlet of the first three-way electromagnetic valve and then is discharged from the discharge port;
setting time interval to switch between the first measurement mode and the second measurement mode, and measuring NO in the reaction chamber and the reference chamber after the gas passes through the NO reaction tube2And calculating the apparent generation rate of ozone by combining the average residence time of the gas in the reaction cavity and the reference cavity.
6. The method of claim 5, wherein the calculation of the apparent ozone generation rate is as follows:
Figure FDA0003119070710000031
wherein [ NO ]2]ambAnd [ NO2]refRespectively representing CAPS NO in the first measurement mode and the second measurement mode2Total NO detected by the detector2Concentration; [ NO ]2]τ，ambAnd [ NO2]τ，refRespectively representing NO when the ambient atmosphere passes through the reaction chamber and the reference chamber in the first measurement mode and the second measurement mode2Concentration of [ O ]3]τ，ambAnd [ O3]τ，refRespectively showing the conversion of ambient atmosphere into NO when the ambient atmosphere passes through the NO reaction tube in the first measurement mode and the second measurement mode2O of (A) to (B)3Concentration, C represents the conversion efficiency, and τ represents the average residence time of ambient atmosphere as it passes through the reaction chamber and the reference chamber.
7. The method for on-line measurement of ozone generation rate and ozone generation susceptibility according to claim 5, further comprising an ozone generation susceptibility region determination step, specifically comprising:
and independently introducing the NO standard gas or the VOCs standard gas into the reaction cavity at the ozone generation rate step by step, detecting the nonlinear response relation between the ozone generation rate and the NO standard gas or the VOCs standard gas, and judging that the ozone in the ambient atmosphere is generated into a NOx sensitive area, a VOCs sensitive area or a transition area.
8. The method of claim 7, further comprising detecting the ozone generation sensitivity of the particulate matter, wherein the system for online measurement of the ozone generation sensitivity and the ozone generation rate is provided with a bypass, and the introduced ambient atmosphere passes through the bypass and is compared with the ozone generation sensitivity measured when the particulate matter filter is introduced in the ozone generation sensitivity region determination step, thereby obtaining the result of the influence of the particulate matter on the ozone generation sensitivity.
9. The method of claim 5 further comprising the step of characterizing said contents including average residence time of reactants in each reaction chamber, wall loss of Ox, O in NO reaction chamber3Conversion to NO2The conversion efficiency of (a).
CN202110671996.9A 2021-06-17 2021-06-17 System and method for online measurement of ozone generation rate and ozone generation sensitivity Pending CN113376158A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
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CN113899846A (en) * 2021-09-13 2022-01-07 四川大学 Ambient air O3Device and method for measuring potential generation
CN114136898A (en) * 2021-11-05 2022-03-04 中国科学院合肥物质科学研究院 System and method for measuring photochemical net generation rate of high-precision cavity ozone
CN115575566A (en) * 2022-08-04 2023-01-06 华北电力大学 Nitrogen oxide measuring system and mass flow controller
CN117929203A (en) * 2024-03-21 2024-04-26 暨南大学 System for on-line measuring uptake constant of atmospheric particulate matters to peroxy free radicals

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113899846A (en) * 2021-09-13 2022-01-07 四川大学 Ambient air O3Device and method for measuring potential generation
CN114136898A (en) * 2021-11-05 2022-03-04 中国科学院合肥物质科学研究院 System and method for measuring photochemical net generation rate of high-precision cavity ozone
CN115575566A (en) * 2022-08-04 2023-01-06 华北电力大学 Nitrogen oxide measuring system and mass flow controller
CN115575566B (en) * 2022-08-04 2023-10-27 华北电力大学 Nitrogen oxide measuring system
CN117929203A (en) * 2024-03-21 2024-04-26 暨南大学 System for on-line measuring uptake constant of atmospheric particulate matters to peroxy free radicals

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