A method for predicting and evaluating concentration of nitrogen trifluoride in an industrial park environment

Abstract

The application discloses a method for predicting and evaluating the environmental concentration of nitrogen trifluoride in an industrial park, which comprises the following steps: collecting the information of enterprises related to the emission of nitrogen trifluoride, geographical information and related environmental parameters in the industrial park; establishing a non-steady-state non-equilibrium multi-medium environmental model, which comprehensively considers the migration and transformation process of pollutants in the atmosphere, water body and soil medium; determining the emission rate, removal rate coefficient and transfer rate coefficient of nitrogen trifluoride; solving the model by using a numerical method; and analyzing and evaluating the solving result. The non-equilibrium non-steady-state multi-medium environmental model is adopted, the migration and transformation process of nitrogen trifluoride in the atmosphere, water body and soil medium is comprehensively considered, and the environmental concentration of nitrogen trifluoride in the industrial park can be more accurately predicted. The method can predict the environmental concentration of nitrogen trifluoride in different regions and at different times in the industrial park, and has higher spatial and temporal coverage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of environmental science, in particular to a method for predicting and evaluating the environmental concentration of nitrogen trifluoride in an industrial park. BACKGROUND

[0002] With the rapid development of industry, the production activities of various enterprises in the industrial park have different degrees of impact on the environment. Nitrogen trifluoride, as an important industrial gas, is widely used in the semiconductor manufacturing industry. However, the emission of nitrogen trifluoride can potentially harm the atmosphere, water bodies and soil media. Therefore, accurately predicting and evaluating the environmental concentration of nitrogen trifluoride in the industrial park is of great significance for formulating effective environmental protection measures and ensuring ecological environment safety.

[0003] Currently, the methods for predicting and evaluating the concentration of pollutants in the environment mainly include monitoring method and diffusion model method. The monitoring method can directly obtain the actual pollutant concentration data, but it has the problems of high monitoring cost, limited time and space coverage. The diffusion model method usually simulates the diffusion process of pollutants in the atmosphere based on certain assumptions, and its accuracy is often affected by model assumptions and parameter selection factors. Therefore, the present application proposes a method for predicting and evaluating the environmental concentration of nitrogen trifluoride in an industrial park to solve the above problems. SUMMARY

[0004] The present application aims to provide a method for predicting and evaluating the environmental concentration of nitrogen trifluoride in an industrial park to solve the problems raised in the background.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a method for predicting and evaluating the environmental concentration of nitrogen trifluoride in an industrial park, comprising the following steps:

[0006] S1, data collection and arrangement, including collecting enterprise information related to nitrogen trifluoride emission in the industrial park, industrial park geographic information and related environmental parameters;

[0007] S2, establish a non-steady-state non-equilibrium multi-medium environmental model, based on the law of conservation of mass, comprehensively describe the concentration change of nitrogen trifluoride in different environmental media, including atmospheric phase, water phase and soil phase model equations, by comprehensively describing the migration and transformation process of pollutants in atmospheric, water and soil environmental media;

[0008] The equation of the atmospheric phase model is:

[0009]

[0010] Where C a represents the concentration of nitrogen trifluoride in the atmosphere; t represents time; represents the atmospheric wind velocity vector; H a represents the atmospheric mixed layer height; k i,a represents the removal rate coefficient of nitrogen trifluoride in the atmosphere; E a represents the emission rate of nitrogen trifluoride in the atmosphere; k j,a represents the transfer rate coefficient from other environmental media to the atmosphere; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0011] The equation of the water phase model is:

[0012]

[0013] wherein C w represents the concentration of nitrogen trifluoride in the water body; k represents the water flow velocity vector; V w represents the water body volume; k i,w represents the removal rate coefficient of nitrogen trifluoride in the water body; E w represents the emission rate of nitrogen trifluoride in the water body; k j,w represents the transfer rate coefficient from other environmental media to the water body; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0014] The equation of the soil phase model is:

[0015]

[0016] wherein C s represents the concentration of nitrogen trifluoride in the soil; k represents the soil water flow velocity vector; V s represents the soil volume; k i,s represents the removal rate coefficient of nitrogen trifluoride in the soil; E s represents the emission rate of nitrogen trifluoride in the soil; k j,s represents the transfer rate coefficient from other environmental media to the soil; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0017] S3, parameter determination, including determination of the emission rate, removal rate coefficient and transfer rate coefficient of nitrogen trifluoride;

[0018] S4, model solving, solving the established environmental model by using a numerical method;

[0019] S5, result analysis and evaluation, predicting the concentration of nitrogen trifluoride in different environmental media, and evaluating the environmental risk of nitrogen trifluoride in the industrial park by using a risk evaluation index.

[0020] Preferably, the information of the enterprises in the collection industrial park involving the emission of nitrogen trifluoride includes the enterprise name, the production process and the nitrogen trifluoride emission amount.

[0021] The geographic information of the industrial park includes the geographic position, the topography and the meteorological data.

[0022] The related environmental parameters include the atmospheric diffusion coefficient, the water body self-purification coefficient and the soil adsorption coefficient.

[0023] Preferably, the model assumption of the environmental model includes that the nitrogen trifluoride emission in the industrial park is continuous and stable, the atmosphere, the water body and the soil medium are all homogeneous mixing systems and the chemical reaction of the pollutants in the environmental medium is ignored.

[0024] Preferably, the emission rate in the parameter determination is determined by the actual monitoring data and the material balance method.

[0025] Preferably, the removal rate coefficient in the parameter determination is determined by consulting the literature and the experimental determination method.

[0026] Preferably, the transfer rate coefficient in the parameter determination is determined by the empirical formula and the model simulation method.

[0027] Preferably, the numerical method adopted in the model solving includes the finite difference method and the finite element method.

[0028] Preferably, the concentration prediction in the result analysis and evaluation is the concentration distribution of the nitrogen trifluoride in the atmosphere, the water body and the soil medium obtained by the model solving, and the environmental concentration of the nitrogen trifluoride in different regions of the industrial park is predicted.

[0029] Preferably, the risk evaluation in the result analysis and evaluation adopts the risk evaluation index to evaluate the environmental risk of the nitrogen trifluoride in the industrial park, and the risk evaluation index includes the potential ecological hazard index and the health risk index.

[0030] Preferably, after the result of the risk evaluation is obtained, according to the evaluation result, the environmental risk level of the nitrogen trifluoride in the industrial park is determined, and the corresponding risk management measures are proposed.

[0031] The technical effects and advantages of the present application are as follows:

[0032] The application adopts a non-equilibrium non-steady-state multi-medium environment model, comprehensively considers the migration and transformation process of nitrogen trifluoride in the atmosphere, water body and soil medium, and can more accurately predict the environmental concentration of nitrogen trifluoride in the industrial park; compared with the traditional monitoring method, the prediction method has lower cost, and does not need a large number of monitoring equipment and manpower investment; the application can predict the environmental concentration of nitrogen trifluoride in different regions and at different times in the industrial park, has higher spatial and temporal coverage, and through the prediction and evaluation of the environmental concentration of nitrogen trifluoride in the industrial park, scientific basis can be provided for the environmental management department to formulate environmental protection measures and optimize the layout of the industrial park. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 The operation flowchart of the prediction and evaluation of the application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the application.

[0035] The application provides an industrial park nitrogen trifluoride environmental concentration prediction and evaluation method as shown in the following formula (I): Figure 1 The method comprises the following steps:

[0036] S1, data collection and arrangement, including collecting enterprise information related to nitrogen trifluoride emission in the industrial park, industrial park geographic information and related environmental parameters;

[0037] Specifically, the collected enterprise information related to nitrogen trifluoride emission in the industrial park includes enterprise name, production process and nitrogen trifluoride emission amount;

[0038] The industrial park geographic information includes geographic position, topography and meteorological data;

[0039] The related environmental parameters include atmospheric diffusion coefficient, water body self-purification coefficient and soil adsorption coefficient.

[0040] S2, establish a non-steady-state non-equilibrium multi-medium environment model, based on the law of conservation of mass, comprehensively consider the migration and transformation process of pollutants in the atmosphere, water body and soil environment medium, describe the concentration change of nitrogen trifluoride in different environmental media, including the model equation of the atmosphere phase, water phase and soil phase;

[0041] The equation of the atmospheric phase model is:

[0042]

[0043] wherein C a represents the concentration of nitrogen trifluoride in the atmosphere; t represents time; represents the atmospheric wind velocity vector; H a represents the atmospheric mixing layer height; k i,a represents the removal rate coefficient of nitrogen trifluoride in the atmosphere; E a represents the emission rate of nitrogen trifluoride in the atmosphere; k j,a represents the transfer rate coefficient from other environmental media to the atmosphere; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0044] The equation of the water phase model is:

[0045]

[0046] wherein C w represents the concentration of nitrogen trifluoride in the water body; t represents time; represents the water flow velocity vector; V w represents the water body volume; k i,w represents the removal rate coefficient of nitrogen trifluoride in the water body; E w represents the emission rate of nitrogen trifluoride in the water body; k j,w represents the transfer rate coefficient from other environmental media to the water body; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0047] The equation of the soil phase model is:

[0048]

[0049] wherein C s represents the concentration of nitrogen trifluoride in the soil; t represents time; represents the soil water flow velocity vector; V s represents the soil volume; k i,s represents the removal rate coefficient of nitrogen trifluoride in the soil; E s represents the emission rate of nitrogen trifluoride in the soil; k j,s represents the transfer rate coefficient from other environmental media to the soil; C j represents the concentration of nitrogen trifluoride in other environmental media;

[0050] Specifically, the model assumptions of the environmental model include that the nitrogen trifluoride emissions in the industrial park are continuous and stable, that the atmosphere, water body and soil media are all homogeneous mixing systems, and that chemical reactions of the pollutants in the environmental media are ignored.

[0051] S3, parameter determination, including determination of the emission rate, removal rate coefficient and transfer rate coefficient of nitrogen trifluoride;

[0052] Specifically, according to the collected enterprise information, the emission rate of nitrogen trifluoride of each enterprise in the industrial park is determined, and the emission rate is determined by actual monitoring data and material balance method in the parameter determination;

[0053] The removal rate coefficient is determined by consulting literature and experimental determination method in the parameter determination, and the removal rate coefficient reflects the removal process of pollutants in different environmental media, which can be determined by consulting literature and experimental determination method, for example, the removal of nitrogen trifluoride in the atmosphere mainly includes dry and wet deposition process, and the removal rate coefficient can be calculated according to the related deposition rate and atmospheric mixing layer height parameters.

[0054] The transfer rate coefficient is determined by empirical formula and model simulation method in the parameter determination, and the transfer rate coefficient describes the transfer process of pollutants between different environmental media, which can be determined by empirical formula and model simulation method, for example, the transfer of nitrogen trifluoride between atmosphere and water body is mainly realized through volatilization and deposition process, and the transfer rate coefficient can be calculated according to the volatilization rate and deposition rate parameters.

[0055] S4, model solving, using numerical method to solve the established environmental model;

[0056] Specifically, the numerical method used in model solving includes finite difference method and finite element method, and in the solving process, appropriate time step and space step need to be selected according to the specific situation to ensure the stability and accuracy of the model.

[0057] S5, result analysis and evaluation, the concentration of nitrogen trifluoride in different environmental media is predicted, and the environmental risk of nitrogen trifluoride in the industrial park is evaluated by using risk evaluation index.

[0058] Specifically, the concentration prediction in result analysis and evaluation is the concentration distribution of nitrogen trifluoride in the atmosphere, water body and soil medium obtained by model solving, and the environmental concentration of nitrogen trifluoride in different areas of the industrial park is predicted.

[0059] Further, the risk evaluation in result analysis and evaluation uses risk evaluation index to evaluate the environmental risk of nitrogen trifluoride in the industrial park, and the risk evaluation index includes potential ecological hazard index and health risk index. After the result of risk evaluation is obtained, according to the evaluation result, the environmental risk level of nitrogen trifluoride in the industrial park is determined, and the corresponding risk management measures are put forward.

[0060] Example one, for the environmental concentration prediction and evaluation of nitrogen trifluoride in industrial park, the specific operation steps are:

[0061] A1, collect information about the enterprises in the industrial park that emit nitrogen trifluoride, including Enterprise A, Enterprise B, and Enterprise C. Through investigation, it is learned that Enterprise A mainly engages in semiconductor manufacturing, with a nitrogen trifluoride emission of 50 tons per day; Enterprise B engages in electronic component production, with a nitrogen trifluoride emission of 80 tons per day; Enterprise C engages in photovoltaic material production, with a nitrogen trifluoride emission of 70 tons per day;

[0062] Obtain the geographical information of the industrial park, which is located in City C. The terrain is mainly plain, and the climate is subtropical monsoon climate. Collect local meteorological data, including wind speed, wind direction, temperature, and humidity.

[0063] Organize relevant environmental parameters. Through literature review and experimental determination, the atmospheric diffusion coefficient is determined to be 0.00016 square meters per second, the water self-purification coefficient is 80.07 per day, and the soil adsorption coefficient is 31.82 liters per kilogram.

[0064] A2, based on the collected data, establish a non-equilibrium non-steady-state multi-medium environmental model for the industrial park. The model assumes that the nitrogen trifluoride emissions in the industrial park are continuous and stable, and that the atmosphere, water, and soil media are homogeneous mixing systems, ignoring the chemical reactions of pollutants in the environmental media.

[0065] Determine the parameters in the model equation. For the atmospheric phase, calculate the emission rate of nitrogen trifluoride in the atmosphere based on meteorological data and emission rate. Determine the removal rate coefficient of nitrogen trifluoride in the atmosphere and the transfer rate coefficient from other environmental media to the atmosphere by consulting literature. For the water and soil phases, use similar methods to determine the corresponding parameters.

[0066] A3, based on the production process and material balance of the enterprises, determine the nitrogen trifluoride emission rates of Enterprise A, Enterprise B, and Enterprise C as 18250 tons per year, 29200 tons per year, and 25550 tons per year, respectively.

[0067] Through literature review and experimental determination, the removal rate coefficient of nitrogen trifluoride in the atmosphere is determined to be 0.08 per day; the removal rate coefficient of nitrogen trifluoride in the water is 0.03 per day; the removal rate coefficient of nitrogen trifluoride in the soil is 0.02 per day.

[0068] Using empirical formula and model simulation methods, the transfer rate coefficient of nitrogen trifluoride between the atmosphere and the water is determined to be 3.18 kilograms per day; the transfer rate coefficient between the atmosphere and the soil is 1.22 x 10 -8 kilograms per day; the transfer rate coefficient between the water and the soil is 2.71 x 10 -13 kilograms per day.

[0069] A4, the finite difference method is used to solve the established non-equilibrium non-steady-state multi-medium environment model, and the time step is determined as 50 hours and the space step is determined as 2000 meters. Through iterative calculation, the concentration distribution of nitrogen trifluoride in the atmosphere, water body and soil medium is obtained.

[0070] A5, according to the model solving result, the concentration distribution of nitrogen trifluoride in the atmosphere, water body and soil medium in the industrial park is drawn, and it is found through analysis that the concentration of nitrogen trifluoride in the atmosphere near enterprise A is relatively high, with a maximum value of 559 mg / m3; the concentration of nitrogen trifluoride in the atmosphere near enterprise B is relatively high, with a maximum value of 636 mg / L; the concentration of nitrogen trifluoride in the atmosphere near enterprise C is relatively high, with a maximum value of 425 mg / kg;

[0071] The environmental risk of nitrogen trifluoride in the industrial park is evaluated by using the potential ecological hazard index. The calculation result shows that the potential ecological hazard index of nitrogen trifluoride in the industrial park is 1.49, which belongs to the medium risk level. According to the evaluation result, the following risk management measures are put forward:

[0072] (1) Strengthen the supervision of enterprises involving nitrogen trifluoride emission, and ensure that the pollutant emission meets the national and local environmental protection standards.

[0073] (2) Optimize the layout of the industrial park, and arrange the enterprises involving nitrogen trifluoride emission as far as possible from the residential areas and sensitive areas.

[0074] (3) Strengthen environmental monitoring, and regularly monitor the atmospheric, water and soil environmental media in the industrial park, so as to timely master the environmental concentration change of nitrogen trifluoride.

[0075] Example two, assuming that there is an industrial park called WZ, and there is an electronic manufacturing enterprise X company in the park. This enterprise will use nitrogen trifluoride in the production process. The park is located in a plain area, surrounded by rivers and farmland, with distinct seasons and southeast prevailing wind direction. For the prediction and evaluation of nitrogen trifluoride environmental concentration in WZ industrial park, the specific operation steps are as follows:

[0076] A1, collect the information of enterprises involving nitrogen trifluoride emission in the industrial park, and through the investigation and monitoring of enterprise X company in the park, determine the main nitrogen trifluoride emission sources, including the tail gas emission port of production workshop, volatilization of storage tank, etc. Record the location, emission amount and emission time rule of each emission source. A production workshop of enterprise X emits about 100 kg of nitrogen trifluoride per day, and the emission location is located in the southeast corner of the park. Collect the production plan of X enterprise to predict the emission amount change in different time periods.

[0077] A2, according to the collected data, establish the non-equilibrium non-steady-state multi-medium environment model of the industrial park. The model assumes that the nitrogen trifluoride emissions in the industrial park are continuous and stable, and the atmosphere, water and soil media are homogeneous mixing systems, and the chemical reaction of pollutants in the environment medium is ignored.

[0078] Determine the parameters in the model equation. The atmospheric diffusion coefficient is calculated by setting up multiple meteorological monitoring stations in the park, collecting wind direction, wind speed, temperature, humidity and other data, and combining the atmospheric diffusion model. Under the condition of wind speed 5 meters / second and stability D level, the atmospheric diffusion coefficient is 0.25 square kilometers / hour; the flow velocity of the river around the park is measured, and the average flow velocity is 0.5 meters / second; soil samples are collected at different locations in the park, and laboratory tests are conducted to determine the soil permeability coefficient of 0.01 cm / s.

[0079] A3, parameter determination, including determination of the emission rate of nitrogen trifluoride, removal rate coefficient and transfer rate coefficient. The transfer rate coefficient between nitrogen trifluoride in the atmosphere and water is 6.11×10 -12 kg / day; the transfer rate coefficient between the atmosphere and the soil is 1.59×10 -3 kg / day; the transfer rate coefficient between water and soil is 8.72×10 -15 kg / day.

[0080] A4, the finite difference method is used to solve the established non-equilibrium non-steady-state multi-medium environment model, and the time step is determined as 80 hours and the space step is determined as 10000 meters. Through iterative calculation, the concentration distribution of nitrogen trifluoride in the atmosphere, water and soil medium is obtained.

[0081] A5, according to the model solving result, draw the concentration distribution diagram of nitrogen trifluoride in the atmosphere, water and soil medium in the industrial park, and analyze that the concentration of nitrogen trifluoride in the atmosphere near enterprise X is higher, with a maximum value of 24.41 mg / L; the maximum concentration of nitrogen trifluoride in the atmosphere 2000 meters away from enterprise X company is 0.28 mg / L;

[0082] The environmental risk of nitrogen trifluoride in the industrial park is evaluated by using the potential ecological hazard index. The calculation result of the potential ecological hazard index of nitrogen trifluoride in the industrial park is 0.02, which belongs to low risk level.

[0083] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that the technical solutions described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalent features, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for predicting and evaluating the concentration of nitrogen trifluoride in an industrial park environment, characterized in that, The prediction and evaluation method comprises the following steps: S1, data collection and arrangement, including collecting enterprise information related to nitrogen trifluoride emission in the industrial park, industrial park geographic information and related environmental parameters; S2, establish a non-steady-state non-equilibrium multi-medium environment model, based on the law of conservation of mass, comprehensive atmospheric, water and soil environmental media pollutant migration and transformation process, describe the concentration change of nitrogen trifluoride in different environmental media, including atmospheric phase, water phase and soil phase model equation; The equation of the atmospheric phase model is: where C a represents the concentration of nitrogen trifluoride in the atmosphere; t represents time; represents the atmospheric wind velocity vector; H a represents the atmospheric mixing layer height; k i,a represents the removal rate coefficient of nitrogen trifluoride in the atmosphere; E a represents the emission rate of nitrogen trifluoride in the atmosphere; k j,a represents the transfer rate coefficient from other environmental media to the atmosphere; C j represents the concentration of nitrogen trifluoride in other environmental media; The equation of the water phase model is: where C w represents the concentration of nitrogen trifluoride in the water body; represents the water flow velocity vector; V w represents the water body volume; k i,w represents the removal rate coefficient of nitrogen trifluoride in the water body; E w represents the emission rate of nitrogen trifluoride in the water body; k j,w represents the transfer rate coefficient from other environmental media to the water body; C j represents the concentration of nitrogen trifluoride in other environmental media; The equation of the soil phase model is: where C s represents the concentration of nitrogen trifluoride in the soil; represents the soil water flow velocity vector; V s represents the soil volume; k i,s represents the removal rate coefficient of nitrogen trifluoride in the soil; E s represents the emission rate of nitrogen trifluoride in the soil; k j,s represents the transfer rate coefficient from other environmental media to the soil; C j represents the concentration of nitrogen trifluoride in other environmental media; S3, parameter determination, including determination of nitrogen trifluoride emission rate, removal rate coefficient and transfer rate coefficient; S4, model solving, numerical method is used to solve the established environmental model; S5, result analysis and evaluation, the concentration of nitrogen trifluoride in different environmental media is predicted, and the environmental risk of nitrogen trifluoride in the industrial park is evaluated by using risk evaluation index.

2. The method according to claim 1, wherein, The collection of enterprise information related to nitrogen trifluoride emission in the industrial park includes enterprise name, production process and nitrogen trifluoride emission; The industrial park geographic information includes geographic location, topography and meteorological data; The related environmental parameters include atmospheric diffusion coefficient, water body self-purification coefficient and soil adsorption coefficient.

3. The method according to claim 1, wherein, The model assumptions of the environmental model include continuous and stable emission of nitrogen trifluoride in the industrial park, uniform mixing system of atmospheric, water and soil media, and neglecting chemical reaction of pollutants in the environmental medium.

4. The method according to claim 1, wherein, The emission rate in the parameter determination is determined by actual monitoring data and material balance method.

5. The method according to claim 4, wherein, The removal rate coefficient in the parameter determination is determined by consulting literature and experimental determination method.

6. The method according to claim 4, wherein, The transfer rate coefficient in the parameter determination is determined by empirical formula and model simulation method.

7. The method according to claim 1, wherein, The numerical method used in the model solving includes finite difference method and finite element method.

8. The method according to claim 1, wherein, The concentration prediction in the result analysis and evaluation is the concentration distribution of nitrogen trifluoride in the atmospheric, water and soil media obtained by model solving, which predicts the environmental concentration of nitrogen trifluoride in different areas of the industrial park.

9. The industrial park NF3 environmental concentration prediction and evaluation method according to claim 8, characterized in that, The risk evaluation in the result analysis and evaluation uses risk evaluation index to evaluate the environmental risk of nitrogen trifluoride in the industrial park, and the risk evaluation index includes potential ecological hazard index and health risk index.

10. The industrial park NF3 environmental concentration prediction and evaluation method according to claim 9, characterized in that, After the result of the risk evaluation is obtained, according to the evaluation result, the environmental risk level of nitrogen trifluoride in the industrial park is determined, and corresponding risk management measures are put forward.

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