CN116429517A - Uniform flow field sampling method for fixed pollution source exhaust - Google Patents
Uniform flow field sampling method for fixed pollution source exhaust Download PDFInfo
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- CN116429517A CN116429517A CN202310184106.0A CN202310184106A CN116429517A CN 116429517 A CN116429517 A CN 116429517A CN 202310184106 A CN202310184106 A CN 202310184106A CN 116429517 A CN116429517 A CN 116429517A
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- 238000005070 sampling Methods 0.000 title claims abstract description 42
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000004088 simulation Methods 0.000 claims abstract description 33
- 239000003344 environmental pollutant Substances 0.000 claims abstract description 27
- 231100000719 pollutant Toxicity 0.000 claims abstract description 27
- 238000004364 calculation method Methods 0.000 claims abstract description 24
- 239000000779 smoke Substances 0.000 claims abstract description 16
- 239000012530 fluid Substances 0.000 claims abstract description 10
- 239000000428 dust Substances 0.000 claims abstract description 9
- 239000002245 particle Substances 0.000 claims abstract description 7
- 238000005259 measurement Methods 0.000 abstract description 4
- 230000007547 defect Effects 0.000 abstract description 3
- 238000001514 detection method Methods 0.000 abstract description 3
- 239000007789 gas Substances 0.000 description 10
- 238000012544 monitoring process Methods 0.000 description 5
- 230000007613 environmental effect Effects 0.000 description 4
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 3
- 239000003546 flue gas Substances 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002411 adverse Effects 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000007943 implant Substances 0.000 description 1
- 238000002360 preparation method Methods 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
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2247—Sampling from a flowing stream of gas
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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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- G06F30/20—Design optimisation, verification or simulation
- G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
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- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/08—Fluids
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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Abstract
The invention discloses a uniform flow field sampling method for fixed pollution source exhaust, which detects boundary working condition parameters of the fixed pollution source exhaust; inputting boundary working condition parameters, and executing simulation calculation by a Fluent solver integrated in the smoke and dust sampling instrument to obtain a fixed pollution source exhaust section speed cloud chart and a pollutant concentration distribution area chart; and selecting measuring points distributed in the uniform flow field of the fixed pollution source exhaust to sample the components of the pollution source smoke according to the simulation result, and selecting an area where the average concentration of the pollutants on the section of the fixed pollution source exhaust is located to sample the concentration of the particles. The method overcomes the defect of the traditional fixed pollution source exhaust sampling, gives a uniform flow field picture of the fixed pollution source exhaust through a fluid simulation model, rapidly positions uniform concentration points, rapidly realizes pollution source concentration measurement, and improves detection precision.
Description
Technical Field
The invention relates to the technical field of environmental monitoring and sampling, in particular to a uniform flow field sampling method for exhaust gas of a fixed pollution source.
Background
The current sampling method for the exhaust of the fixed pollution source by environmental monitoring mostly adopts a method for measuring particulate matters in the exhaust of the fixed pollution source and sampling gaseous pollutants (GB/T16157-1996) and a technical specification for monitoring the exhaust of the fixed pollution source (HJ/T397-2007), wherein the sampling of the gaseous pollutants is carried out in a sampling section by taking a point close to the center of a flue as a sampling point, and the sampling of the particulate matters is carried out by selecting the measuring point according to an equal-area integral ring method. The method and the specification generally consider that the gaseous pollutants are uniformly mixed on a sampling section, and neglect adverse effects on the uniform mixing of the gas caused by time gradient, temperature gradient, speed gradient, viscosity, agglomeration effect of gas molecules and the like; the sampling points are selected on the intersection point of the area center lines of the rings and two diameter lines which are vertically intersected, wherein one diameter line is in the plane with the largest expected concentration change, and the elastic collision of pipe wall particles, the diameter-changing size of a pipe, the flue gas temperature and humidity and the interference caused by turbulent flow are ignored, so that the plane sampling with the largest expected concentration change has extremely large uncertainty.
The preparation and execution of the method and the specification have been carried out for decades, and have great application limitations, while the national requirements on the emission factors and emission limit values of atmospheric pollutants are higher and higher, the existing method and the specification cannot truly reflect the uniformity of the actual distribution of pollutants in the flue, so that great difference exists between the concentration of sampled flue gas and the actual concentration of flue gas in the flue; and the sampling operation steps are more, the random error probability is increased, the fine sampling requirement cannot be met, and difficulties are brought to later sample component analysis, data compliance discrimination and design scientificity and accuracy of environmental protection equipment. No instrument is available at present for intuitively sampling the concentration of pollutants according to the change of a flow field through observing the markets of environmental monitoring instruments at home and abroad.
Disclosure of Invention
The invention aims to provide a uniform flow field sampling method for fixed pollution source exhaust, which overcomes the defects of the traditional fixed pollution source exhaust sampling, gives a uniform flow field picture of the fixed pollution source exhaust through a fluid simulation model, rapidly positions uniform concentration points, rapidly realizes pollution source concentration measurement, and improves detection precision.
In order to solve the technical problems, the uniform flow field sampling method for fixing the pollution source exhaust gas comprises the following steps:
detecting boundary working condition parameters of fixed pollution source exhaust, pre-measuring parameters of gas pressure, gas temperature and flow velocity values in a flue according to a predicted flow velocity method by using an inherent temperature-pressure flow measuring device of a smoke and dust sampling instrument, and determining boundary working condition parameter values according to the measured flue size;
integrating a Fluent solver in the smoke and dust gas sampling instrument, inputting boundary condition parameter values into the Fluent solver to perform simulation calculation, inputting the boundary condition parameter values into the Fluent solver, selecting a reasonable physical model, setting a sub-relaxation factor value, and automatically performing the simulation calculation in the background to obtain a required simulation result;
and thirdly, according to simulation results, selecting uniform flow field distribution of the exhaust of the fixed pollution source, wherein the uniform flow field distribution takes relative standard deviation CV and uniformity index gamma v as discrimination bases, the smaller the CV value is, the higher the flow field uniformity is, the larger the gamma v value is, the better the flow uniformity is, according to the discrimination standards, combining simulation calculation results, obtaining flow field distribution conditions on the section of the flue, selecting uniform flow field distribution points to sample the smoke components of the pollution source, and selecting the area where the average concentration of pollutants on the section of the exhaust of the fixed pollution source is located to sample the concentration of the particles.
Further, the condition of the area where the average concentration of the pollutants is located depends on the uniformity of a flow field, the Fluent solver performs computational fluid dynamics simulation calculation including second-order discrete CFD calculation, the value of a solving variable is monitored to ensure that the change of the variable value can be directly ignored in two iterations, each physical quantity is verified to be conserved, and the rationality of a calculation result is judged based on engineering experience, so that the average concentration area of the pollutants is rapidly and accurately judged.
Further, the simulation results comprise a pollution source exhaust cross-sectional velocity cloud image and each pollutant concentration distribution area image.
The technical scheme is adopted by the uniform flow field sampling method for the exhaust of the fixed pollution source, namely, the method detects the boundary working condition parameters of the exhaust of the fixed pollution source; inputting boundary working condition parameters, and executing simulation calculation by a Fluent solver integrated in the smoke and dust sampling instrument to obtain a fixed pollution source exhaust section speed cloud chart and a pollutant concentration distribution area chart; and selecting measuring points distributed in the uniform flow field of the fixed pollution source exhaust to sample the components of the pollution source smoke according to the simulation result, and selecting an area where the average concentration of the pollutants on the section of the fixed pollution source exhaust is located to sample the concentration of the particles. The method overcomes the defect of the traditional fixed pollution source exhaust sampling, gives a uniform flow field picture of the fixed pollution source exhaust through a fluid simulation model, rapidly positions uniform concentration points, rapidly realizes pollution source concentration measurement, and improves detection precision.
Detailed Description
The invention relates to a uniform flow field sampling method for fixed pollution source exhaust, which comprises the following steps:
detecting boundary working condition parameters of fixed pollution source exhaust, pre-measuring parameters of gas pressure, gas temperature and flow velocity values in a flue according to a predicted flow velocity method by using an inherent temperature-pressure flow measuring device of a smoke and dust sampling instrument, and determining boundary working condition parameter values according to the measured flue size;
integrating a Fluent solver in the smoke and dust gas sampling instrument, inputting boundary condition parameter values into the Fluent solver to perform simulation calculation, inputting the boundary condition parameter values into the Fluent solver, selecting a reasonable physical model, setting a sub-relaxation factor value, and automatically performing the simulation calculation in the background to obtain a required simulation result;
and thirdly, according to simulation results, selecting uniform flow field distribution of the exhaust of the fixed pollution source, wherein the uniform flow field distribution takes relative standard deviation CV and uniformity index gamma v as discrimination bases, the smaller the CV value is, the higher the flow field uniformity is, the larger the gamma v value is, the better the flow uniformity is, according to the discrimination standards, combining simulation calculation results, obtaining flow field distribution conditions on the section of the flue, selecting uniform flow field distribution points to sample the smoke components of the pollution source, and selecting the area where the average concentration of pollutants on the section of the exhaust of the fixed pollution source is located to sample the concentration of the particles.
The measurement of the relative standard deviation CV representing the relative variation is a dimensionless value, is used for comparing the total discreteness with remarkably different average values, and can also be used for comparing the improvement degree of the uniformity of the flow field; the uniformity index gamma v is defined based on statistical deviation, can comprehensively reflect the fluid velocity distribution characteristic of the section of the whole flue, and has the characteristics of strong comparability and wider application range.
Preferably, the condition of the area where the average concentration of the pollutant is located depends on the uniformity of a flow field, the Fluent solver performs calculation and comprises second-order discrete CFD calculation fluid dynamics simulation calculation, the value of a solving variable is monitored to ensure that the change of the variable value can be directly ignored in two iterations, each physical quantity is verified to be conserved, and the rationality of a calculation result is judged based on engineering experience, so that the average concentration area of the pollutant is rapidly and accurately judged.
Preferably, the simulation results comprise a pollution source exhaust cross-sectional velocity cloud and a respective pollutant concentration profile.
The method utilizes a computer fluid simulation technology to implant computer fluid simulation software into a smoke and dust smoke sampling instrument, inputs exhaust boundary working condition parameters with certain conditions, automatically executes simulation calculation in the background to obtain a required simulation result, obtains an exhaust flow field distribution picture and a variation value according to the simulation result, and selects measuring points of uniform flow field distribution and a region where the average concentration of pollutants is located to sample the concentration of pollutant source smoke components and particles. And accurate and reliable scientific analysis data is provided for fine sampling and reflecting the dynamic distribution change of pollutants in the flue in real time.
According to the method, the computer fluid simulation model is adopted for calculation intervention, so that dynamic change of the flow field of the internal section of the flue and the distribution state of the concentration of pollutants can be more intuitively mastered, sampling errors caused by the existing standards and specifications are avoided, the collected samples are more representative, the problem that the traditional sampling method cannot solve is solved, the method has the characteristics of rapidness, intuitiveness, reliability and high sampling accuracy, the problems of complicated time consumption, low effectiveness, high cost and the like of the traditional sampling method are overcome, and the blank that the traditional environment monitoring instrument does not carry out intuitive sampling of the components and the concentration of the pollutants according to the change of the flow field is filled.
Claims (3)
1. The uniform flow field sampling method for the exhaust gas of the fixed pollution source is characterized by comprising the following steps of:
detecting boundary working condition parameters of fixed pollution source exhaust, pre-measuring parameters of gas pressure, gas temperature and flow velocity values in a flue according to a predicted flow velocity method by using an inherent temperature-pressure flow measuring device of a smoke and dust sampling instrument, and determining boundary working condition parameter values according to the measured flue size;
integrating a Fluent solver in the smoke and dust gas sampling instrument, inputting boundary condition parameter values into the Fluent solver to perform simulation calculation, inputting the boundary condition parameter values into the Fluent solver, selecting a reasonable physical model, setting a sub-relaxation factor value, and automatically performing the simulation calculation in the background to obtain a required simulation result;
and thirdly, according to simulation results, selecting uniform flow field distribution of the exhaust of the fixed pollution source, wherein the uniform flow field distribution takes relative standard deviation CV and uniformity index gamma v as discrimination bases, the smaller the CV value is, the higher the flow field uniformity is, the larger the gamma v value is, the better the flow uniformity is, according to the discrimination standards, combining simulation calculation results, obtaining flow field distribution conditions on the section of the flue, selecting uniform flow field distribution points to sample the smoke components of the pollution source, and selecting the area where the average concentration of pollutants on the section of the exhaust of the fixed pollution source is located to sample the concentration of the particles.
2. The method for uniform flow field sampling of a stationary source exhaust according to claim 1, wherein: the condition of the area where the average concentration of the pollutants is located depends on the uniformity of a flow field, the Fluent solver performs calculation including second-order discrete CFD calculation fluid dynamics simulation calculation, the value of a solving variable is monitored to ensure that the change of the variable value can be directly ignored in two iterations, each physical quantity is verified to reach conservation, and the rationality of a calculation result is judged based on engineering experience, so that the average concentration area of the pollutants is rapidly and accurately judged.
3. The method for uniform flow field sampling of a stationary source exhaust according to claim 1, wherein: the simulation results comprise a pollution source exhaust cross-section velocity cloud chart and various pollutant concentration distribution area charts.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117491100A (en) * | 2023-12-28 | 2024-02-02 | 杭州泽天春来科技股份有限公司 | Flue gas constant-speed sampling device and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117491100A (en) * | 2023-12-28 | 2024-02-02 | 杭州泽天春来科技股份有限公司 | Flue gas constant-speed sampling device and method |
| CN117491100B (en) * | 2023-12-28 | 2024-04-12 | 杭州泽天春来科技股份有限公司 | Flue gas constant-speed sampling device and method |
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