Three-stage collaborative control design of contaminated site vocs vapor intrusion into workshop and single-point concentration contribution quantification evaluation method

Abstract

The application discloses a three-section type collaborative control design and single-point concentration contribution quantitative evaluation method for VOCs steam invasion of a workshop in a contaminated site, which is a'source blocking + global dilution + work station protection' method and a multi-control measure calculation and evaluation system. The implementation steps are as follows: site basic parameter survey; source SSD system design and parameter calibration; workshop comprehensive ventilation system standardized design; work station local exhaust system standardized design; three-section system joint stable operation and collaborative concentration collection; multi-measure contribution quantitative evaluation calculation; and system load optimization adjustment. The application initiates a three-section type standardized complete design method, is equipped with complete analysis calculation formulas, couples the boundaries of underground soil gas and indoor ventilation double pollution sources, is matched with real working conditions of a production workshop, realizes quantitative splitting of treatment effects through a multi-measure contribution quantitative evaluation model, adapts to the 'production and control' requirements of domestic production enterprises, and has strong universality and is compatible with various VOCs contaminated workshops.

Description

Technical Field

[0001] This invention relates to the interdisciplinary fields of contaminated site remediation, industrial ventilation, occupational health and safety, and building environment numerical simulation, specifically to a three-stage collaborative control design for VOCs vapor intrusion into a workshop in a contaminated site and a method for quantitatively assessing the contribution of single-point concentration. Background Technology

[0002] In sites contaminated with VOCs in soil and groundwater, underground volatile organic compounds can cause vapor intrusion through soil vapor permeation, continuously seeping into indoor factory buildings and causing VOC concentrations to exceed standards, endangering the occupational health of operators. Existing vapor intrusion control technologies are divided into two independent technical routes: underground source containment and indoor ventilation dilution. These technologies are fragmented and have many shortcomings. Representative existing technologies are as follows:

[0003] Ma Jie's monograph, "Risk Assessment and Control of VOCs Vapor Intrusion in Contaminated Sites," only introduces two types of underground source control methods: SSD (Supply Slab Depressurization) and geomembranes. It can only qualitatively assess the effectiveness of these methods and lacks a comprehensive system for ventilation throughout the workshop and coordinated local exhaust ventilation at workstations. Therefore, it cannot quantify the percentage reduction in VOC concentration at personnel breathing points caused by source control. The US EPA's OSWER 9200.2-154 vapor intrusion assessment technical guidelines only address negative pressure systems for the foundation slab in low-rise residential buildings and are not adapted to 24-hour continuous production or multi-fixed-workstation industrial plants. They rely on a single barrier technology and lack a quantitative calculation model that couples multiple measures.

[0004] CN113263947A discloses a bottom-mounted geomembrane and shallow air extraction barrier device for the plant, which only blocks underground VOCs input but lacks a corresponding indoor tiered ventilation system. It relies solely on comparing concentrations before and after treatment to assess the effectiveness, without standardized quantitative calculation formulas, and the engineering design depends on empirical calculations. CN114838825A describes a workshop local exhaust system that only treats process-generated VOCs, completely ignoring continuous underground vapor intrusion. It cannot be used in conjunction with a floor pressure reduction barrier system and lacks a coupled mass balance model for underground gas infiltration and indoor ventilation. CN115672012A describes a comprehensive ventilation and control system that only dilutes existing indoor pollutants, failing to block continuous underground VOC input. This results in high ventilation energy consumption, a lack of three-level collaborative design logic, and an inability to differentiate the pollution control contributions of different ventilation levels.

[0005] The literature on ventilation coupled with CFD simulation in enclosed spaces published by Wu Fan et al. only conducts numerical simulations for indoor anthropogenic pollution sources, does not introduce the boundary condition of continuous seepage of underground soil gas, can only qualitatively analyze the ventilation effect, and does not derive analytical calculation formulas that can be directly implemented in engineering, thus failing to quickly complete the quantitative assessment of the contribution of multiple treatment measures.

[0006] In summary, existing technologies have five major flaws:

[0007] First, the technology system is fragmented, lacking a standardized design process that integrates "source blocking - full-area dilution - workstation protection". The pollution control capacity of a single treatment method is limited, making it difficult for factory VOCs to consistently meet occupational exposure limits, resulting in high overall energy consumption.

[0008] Second, the pollution boundaries are fragmented, and existing models cannot simultaneously couple the dual boundaries of continuous underground soil gas infiltration and indoor pollutant diffusion, resulting in large deviations in air volume and negative pressure design calculations.

[0009] Third, the lack of steady-state analytical equations necessitates repeated CFD iterative simulations in engineering design, resulting in long design cycles and high professional barriers.

[0010] Fourth, there is no quantitative assessment model for the concentration contribution of multiple measures. It can only compare the total concentration difference before and after treatment, and cannot separate the individual reduction effects of SSD blocking, full fresh air and local exhaust air, making it difficult to guide the energy-saving optimization of the system.

[0011] Fifth, the existing barrier and ventilation solutions are poorly adapted to different scenarios. They are mostly designed for sites where production has ceased or for residential buildings, and cannot meet the policy requirements of domestic enterprises that are in operation and need to carry out renovations without stopping production and to manage and control production simultaneously. Summary of the Invention

[0012] This invention discloses a three-stage collaborative control design and a method for quantitatively assessing the single-point concentration contribution of VOCs vapor intrusion into workshops in contaminated sites. It constructs a three-level collaborative design system encompassing source, overall area, and workstation levels, and establishes a set of coupled analytical equations for underground gas infiltration and indoor ventilation. For scenarios involving continuous underground VOCs vapor intrusion into workshops, it provides a complete system design method combining source blocking, overall dilution, and workstation protection, as well as a quantitative calculation and assessment system for the concentration reduction contribution of multiple control measures. It pioneers a quantitative assessment model for the concentration contribution of multiple treatment measures, achieving standardized design, quantitative effect evaluation, and system energy-saving optimization for contaminated plant treatment. This method is applicable to industrial plants in production facilities such as chemical, pharmaceutical, coating, and petrochemical plants with soil / groundwater VOCs pollution. It is suitable for the design, operation optimization, and quantitative evaluation of pollution control engineering for "simultaneous production and control" in operating enterprises, and is adaptable to various scenarios involving non-stop retrofitting of VOCs-contaminated plants in production.

[0013] This invention is achieved through the following technical solution:

[0014] A three-stage collaborative control design and single-point concentration contribution quantification method for VOCs vapor intrusion into workshops in contaminated sites includes a standardized design method for a three-stage hierarchical collaborative system and a quantification method for the contribution of multiple control measures to VOC concentration reduction at single points. The standardized design method for the three-stage hierarchical collaborative system specifically includes the following operational steps:

[0015] Step S1. Site foundation parameter survey:

[0016] S11. Obtaining total underground VOC migration fluxes through soil gas monitoring. ;

[0017] S12. Determine the natural air leakage in the workshop using a closed-loop test. ;

[0018] S13. Shut down all ventilation barriers and ensure the respiratory tract of personnel has no controlled baseline concentration. ;

[0019] S14. Determine occupational exposure limits in the workshop. Mark the coordinates of all fixed operation stations;

[0020] Step S2. Design and parameter calibration of the source SSD baseboard step-down system:

[0021] S21. Flux decay formula based on pollutant mass conservation formula Attenuation coefficient calculation formula Calculate the target flux attenuation coefficient Match the negative pressure parameters of the base plate with the air volume of the soil air extraction fan;

[0022] S22. The SSD baseboard voltage reduction system was run independently; the actual concentration at the corresponding workstation was measured. Verify the baseline concentration calculation formula when only SSD is enabled. The error between the calculated value and the actual measured value;

[0023] Step S3. Standardized design of the workshop's comprehensive fresh air system:

[0024] S31. Set the permissible background concentration for the entire workshop area. Substitute into the reverse design formula for global fresh air volume Calculate the minimum global fresh air volume ;

[0025] S32. Turn off the SSD and the local exhaust system at the workstation, and run the general ventilation system alone. Measure the concentration at the workstation. Verify the formula for calculating the baseline concentration when only full fresh air is activated. Calculation accuracy;

[0026] Step S4. Standardized design of local exhaust ventilation system for workstations:

[0027] S41. Based on occupational limits To achieve the control target, the reverse design formula for workstation exhaust volume is substituted. Calculate the minimum exhaust volume for each workstation ;

[0028] S42. Shut down the SSD system, ensure full ventilation, and operate the local exhaust fan separately to measure the concentration at the workstation. Verify the formula for calculating the baseline concentration when only local exhaust ventilation is activated. ;

[0029] Step S5. Stable operation and coordinated concentration acquisition of the three-stage system:

[0030] After simultaneously activating SSD, full fresh air system, and local exhaust system, and operating stably for 24 hours, the steady-state VOC concentration in the breathing zone of personnel was collected. The cooperative steady-state concentration satisfies the formula ;

[0031] Step S6. Calculation of the contribution quantification of multiple measures:

[0032] S61. Calculate the total reduction concentration of the three-stage system operating in coordination relative to the uncontrolled condition: ;

[0033] S62. Calculate the independent concentration reductions under the three types of control measures respectively:

[0034] Source SSD independent concentration reduction ;

[0035] Comprehensive fresh air system independently reduces concentration ;

[0036] Independent concentration reduction in local exhaust ventilation at workstations ;

[0037] S63. Calculate the concentration reduction contribution of the three types of control measures respectively:

[0038] Source SS contribution ;

[0039] Comprehensive fresh air contribution ;

[0040] Contribution of local exhaust ventilation at workstations ;

[0041] S64. Verify constraints Determine the validity of the monitoring data and calculation results;

[0042] Step S7. System load optimization and adjustment:

[0043] S71. Iteratively optimize the parameters of the entire system based on the contribution values ​​of the three types of measures. If the contribution of a certain type of system is low, it indicates that the pollution control potential has not been released. Increase the fan air volume and the negative pressure of the base plate.

[0044] S72. If the contribution of a certain type of system is too high, it indicates that the air volume is redundant. Reduce the fan power to lower the operating energy consumption.

[0045] S73. Repeat steps S2 to S6 iteratively until the station's coordinated steady-state concentration is reached. Moreover, the entire governance system has the lowest overall energy consumption.

[0046] Furthermore, in step S1, the basic parameter survey includes: surveying and obtaining the total underground VOC migration flux. (mg / h) Workshop natural air infiltration (m³ / h), baseline concentration at uncontrolled breathing points in the workshop (mg / m³), Workshop allowable occupational exposure limit (mg / m³), the fundamental formula for steady-state mass conservation under uncontrolled operating conditions: .

[0047] Furthermore, the source SSD system design in step S2:

[0048] Calculate the VOC influx attenuation coefficient (0~1), Formula for calculating residual VOC flux:

[0049] ,

[0050] In the formula: — Remaining VOC flux entering the room after SSD blocking, mg / h; The pressure on the base plate increases monotonically as the negative pressure increases.

[0051] SSD system negative pressure matching calculation formula (calculating attenuation coefficient given target remaining flux):

[0052] ,

[0053] Match the negative pressure of the base plate with the air volume of soil gas extraction based on the target remaining flux.

[0054] Furthermore, the comprehensive fresh air system design in step S3 includes:

[0055] Workshop background concentration under conditions of SSD only on and full ventilation In the formula: —Base concentration in the workshop after full dilution, mg / m³

[0056] Inverse calculation of global fresh air volume (given) Solve ):

[0057] .

[0058] Furthermore, the design of the local exhaust system for the workstation in step S4:

[0059] The final concentration of the three-stage system operating synchronously at the workstation: In the formula: — The final stable VOC concentration at the personnel respiratory monitoring point was mg / m³.

[0060] The minimum workstation exhaust volume is calculated in reverse based on occupational limits (given occupational limits). Find the minimum ): .

[0061] Furthermore, the method for quantifying and evaluating the contribution of multiple control measures to VOC concentration reduction at a single point specifically includes the following operational steps:

[0062] (1) Calculate the workstation reference concentration when the single system is running independently, including:

[0063] ① Only enable the source SSD (with general ventilation and local exhaust ventilation disabled) at the baseline concentration. :

[0064] ;

[0065] ② Only the baseline concentration is set when the full fresh air system is activated (SSD and local exhaust systems are disabled). :

[0066] ;

[0067] ③ Only local exhaust ventilation is activated (SSD off, general ventilation) to achieve the baseline concentration. :

[0068] ;

[0069] (2) Calculate the total reduction concentration of the three stages: ;

[0070] (3) Calculate the concentration reduction independently for each of the three types of measures:

[0071] ①Source base plate pressure reduction to independently reduce concentration :

[0072] ② Comprehensive fresh air dilution and independent concentration reduction :

[0073] ③ Independent reduction of concentration in local exhaust ventilation at workstations :

[0074] ;

[0075] (4) Calculate the concentration reduction contribution of each measure:

[0076] ① Source SSD contribution :

[0077] ②Comprehensive fresh air contribution :

[0078] ③ Contribution of local exhaust ventilation :

[0079] ,

[0080] Constraint verification conditions: It is used to verify the accuracy of calculated and monitored data.

[0081] Furthermore, the three control levels in the assessment method are, in order, the source intrusion prevention and control layer, the overall fresh air dilution layer, and the local workstation protection layer.

[0082] Furthermore, the source intrusion prevention and control layer adopts a bottom plate pressure reduction SSD system to block the migration of VOC vapor from underground soil into the room; the overall fresh air dilution layer adopts a workshop displacement-type comprehensive ventilation system to dilute the background concentration of VOCs throughout the workshop; and the local workstation protection layer adopts an operator breathing belt directional local exhaust system to quickly remove pollutants from the core exposure areas of personnel.

[0083] Beneficial effects: This invention presents a three-stage collaborative control design and a method for quantitatively assessing the contribution of single-point concentrations to VOCs vapor intrusion into workshops in contaminated sites. It is the first to propose a three-stage collaborative design and supporting analytical formulas, eliminating the need for CFD simulation; it couples dual pollution boundaries to improve control stability; it allows for the quantification and breakdown of treatment effects; it supports phased retrofitting without production interruption; the model is universally applicable to various VOCs-contaminated plants and complies with relevant national standards. Specifically, it includes the following aspects:

[0084] 1. This invention pioneers a three-stage collaborative standardized design process of source blocking, global dilution, and workstation protection, with complete steady-state analytical calculation formulas. It eliminates the need for repeated CFD simulation iterations, significantly shortens the design cycle of pollution plant treatment solutions, and lowers the threshold for engineering use.

[0085] 2. A set of coupled mass balance equations for underground soil gas infiltration and indoor ventilation was constructed, with simultaneous dual pollution boundaries. The calculation results of air volume and negative pressure closely match the actual continuous gas infiltration conditions in the production plant, and the stability of VOCs control compliance was significantly improved.

[0086] 3. It pioneered a quantitative assessment model for the concentration contribution of multiple treatment measures, which can accurately separate the pollution control effects of SSD blocking, comprehensive fresh air, and local exhaust air, and intuitively identify redundant air volume units and weak links, thereby reducing the overall energy consumption of the system under the same compliance conditions.

[0087] 4. The three-stage system can be constructed in stages and put into operation in sections without the need for the entire plant to shut down, meeting the "production and control" transformation policy requirements of domestic chemical, coating, and pharmaceutical companies that are still producing polluting products;

[0088] 5. The model is highly versatile and is not limited by workshop size or VOCs type. It can be used in various soil VOCs-contaminated workshops, such as those with benzene series compounds, chlorinated hydrocarbons, and petroleum hydrocarbons, and fully complies with relevant national standards for soil management and occupational health of construction land. Attached Figure Description

[0089] Figure 1 This is a complete flowchart of the three-stage system design and contribution evaluation of the present invention.

[0090] Figure 2 This is the core calculation logic diagram of the three-stage collaborative control design and single-point concentration contribution quantification assessment method for VOCs vapor intrusion into workshops in contaminated sites, as presented in this invention.

[0091] Figure 3 This is a schematic diagram of the three-section control space layout of the contaminated site workshop according to the present invention;

[0092] Figure 3 The symbols in the diagram represent: ①. Reinforced concrete floor; ②. Gravel air-conducting layer under the floor slab; ③. Perforated soil air extraction pipeline network; ④. SSD variable frequency negative pressure fan (source blocking unit); ⑤. Replacement fresh air supply outlet at the top of the workshop; ⑥. Total exhaust outlet at the bottom of the workshop (total dilution unit); ⑦. Fixed workstation for operators; ⑧. Top-suction local exhaust hood in the breathing zone (local protection unit); ⑨. VOC online monitoring point (personnel breathing zone, contribution assessment sampling point). Detailed Implementation

[0093] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings: These embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0094] like Figure 1 , 2 As shown, the three-stage collaborative control design and single-point concentration contribution quantification assessment method for VOCs vapor intrusion into the workshop of a contaminated site includes two core modules: Module 1 is a standardized design method for a three-stage hierarchical collaborative system (with a complete set of analytical calculation formulas for air volume and negative pressure); Module 2 is a quantitative assessment method for the contribution of multiple control measures to single-point VOCs concentration reduction (with a set of contribution calculation equations). The overall implementation includes steps such as site survey, three-stage system step-by-step design, system joint commissioning, quantitative assessment of contribution, and system parameter optimization.

[0095] like Figure 3As shown, a gravel air-guiding layer ② is installed beneath the reinforced concrete floor ①. A perforated soil gas extraction pipeline network ③ is laid within the gravel air-guiding layer ②. This network connects to an SSD variable frequency negative pressure fan ④ located outside the factory building via pipes to extract VOCs volatile from the original soil layer, forming a negative pressure barrier on the floor. C represents the source blocking unit. Above the reinforced concrete floor ①, a fixed operator workstation ⑦ is set up in the middle of the factory building interior. Above the operator workstation ⑦, VOC online monitoring points ⑨ and a top-suction local exhaust hood ⑧ are arranged sequentially. A fresh air supply system for the upper part of the factory building interior is also provided. Air outlet ⑤ and the operator's fixed workstation ⑦ are symmetrically arranged on both sides below the bottom of the workshop's total exhaust vent 6. B represents the total dilution unit. VOC online monitoring point ⑨ collects the VOC concentration in the breathing zone in real time and transmits the signal to the SSD variable frequency negative pressure fan ④, the upper replacement fresh air supply vent ⑤, and the top suction local exhaust hood ⑧ of the breathing zone. These coordinate the source extraction, fresh air supply, and local exhaust. A portion of the VOC generated at the operator's fixed workstation ⑦ is directly captured by the top suction local exhaust hood ⑧ of the breathing zone, and the remaining pollutants are collected with the replacement airflow and discharged to the bottom of the workshop's total exhaust vent 6. C represents the local protection unit.

[0096] Three-level control hierarchy definition:

[0097] ① Source intrusion prevention layer: The SSD system of the bottom plate reduces pressure and blocks VOC vapor from the underground soil from migrating into the room;

[0098] ② Overall fresh air dilution layer: The workshop's displacement ventilation system dilutes the background concentration of VOCs throughout the indoor area;

[0099] ③ Local Workstation Protection Layer: Operator breathing belt with directional local exhaust system to quickly remove pollutants from the core exposure area of ​​personnel.

[0100] Module 1: Standardized Design Method and Complete Set of Calculation Formulas for Three-Stage Collaborative Systems

[0101] I. Basic Parameter Survey and Basic Equations (Preliminary Calculations)

[0102] 1. Basic survey parameters: Total underground VOCs migration flux (mg / h) Workshop natural air infiltration (m³ / h), baseline concentration at uncontrolled breathing points in the workshop (mg / m³), Workshop allowable occupational exposure limit (mg / m³).

[0103] 2. Fundamental formula for steady-state mass conservation in an uncontrolled indoor environment:

[0104] .

[0105] II. Source Intrusion Prevention Layer: Design Methods and Formulas for Base Plate Downsampling SSD Systems

[0106] 1. Design Objectives: Determine the negative pressure value of the foundation slab, the soil gas extraction air volume, and calculate the VOC migration flux attenuation coefficient. (0~1).

[0107] 2. Flux decay calculation formula:

[0108] ,

[0109] In the formula: — Remaining VOC flux entering the room after SSD blocking, mg / h; It increases monotonically as the negative pressure on the base plate increases.

[0110] 3. SSD System Negative Pressure Matching Calculation Formula (Calculating the Attenuation Coefficient Given the Target Remaining Flux):

[0111] ,

[0112] III. Overall Fresh Air Dilution Layer: Design Methods and Formulas for Comprehensive Replacement Ventilation in Workshops

[0113] 1. Design Objective: Given the allowable background concentration in the entire indoor area, calculate the required fresh air volume for the entire area. .

[0114] 2. Steady-state concentration formula with SSD only activated and full ventilation, no local exhaust:

[0115] In the formula: — The background concentration in the workshop after full dilution, mg / m³.

[0116] 3. Reverse design formula for total fresh air volume (given) Solve ):

[0117] ,

[0118] IV. Local Workstation Protection Layer: Design Methods and Formulas for Local Exhaust Ventilation Systems at Workstations

[0119] 1. Design Objective: Based on the overall background concentration, calculate the required exhaust volume for each workstation to meet the workstation limits. .

[0120] 2. Formula for the final steady-state concentration of the three-stage system operating synchronously:

[0121] In the formula: — The final stable VOC concentration at the personnel respiratory monitoring point was mg / m³.

[0122] 3. Reverse design formula for workstation exhaust volume (given occupational limits) Find the minimum ):

[0123] .

[0124] Module 2: Measurement and Assessment Methods and Formulas for the Contribution of Single-Point VOC Concentration to Three Types of Control Measures

[0125] Evaluation logic: Calculate the baseline concentration at each workstation when only a single control measure is implemented, compare the total reduction of the three-stage coordinated system, break down the concentration reduction values ​​of source SSD, comprehensive fresh air, and local exhaust air, and calculate the corresponding contribution percentage.

[0126] 1. Formula for calculating the baseline concentration for independent operation of a single measure

[0127] ① Only enable the source SSD (with general ventilation and local exhaust ventilation disabled) at the baseline concentration. :

[0128] ② Only turn on full fresh air (turn off SSD, local exhaust air) to achieve the baseline concentration. :

[0129] ③ Only local exhaust ventilation is turned on (SSD off, full ventilation) to achieve the baseline concentration. :

[0130] .

[0131] 2. Formula for calculating total concentration reduction

[0132] Compared to uncontrolled operation, the total VOC concentration reduction during three-stage coordinated operation is: .

[0133] 3. Formula for calculating concentration reduction using a single measure

[0134] ①Source base plate pressure reduction to independently reduce concentration :

[0135] ② Comprehensive fresh air dilution and independent concentration reduction :

[0136] ③ Independent local exhaust ventilation at workstations reduces concentration :

[0137] .

[0138] 4. Calculation formula for the concentration reduction contribution of the three types of control measures (unit: %)

[0139] ① Source SSD contribution :

[0140] ②Comprehensive fresh air contribution :

[0141] ③ Contribution of local exhaust ventilation :

[0142] ,

[0143] Constraint verification conditions: It is used to verify the accuracy of calculated and monitored data.

[0144] Example 1: Design and Contribution Assessment of Vulnerability Intrusion in a Small-Scale Chemical Plant for Pesticide Intermediates (TCE)

[0145] 1. Basic parameters of site survey

[0146] A pesticide production workshop was found to have underground contamination with trichloroethylene; the workshop has a volume of 1200 m³.

[0147] Total underground VOCs migration flux ;

[0148] Workshop natural air leakage ;

[0149] Uncontrolled workstation reference concentration ;

[0150] Occupational exposure limits .

[0151] 2. Standardized design calculations for a three-stage system

[0152] (1) Source SSD system design: Set the base plate negative pressure to -10Pa, and measure the flux attenuation coefficient. Remaining underground flux:

[0153] (2) Comprehensive fresh air design: setting the baseline for the entire area ,:

[0154] ,

[0155] (3) Local exhaust ventilation design at workstations: Substitute into formula (7) to find the minimum exhaust volume. ,

[0156] 3. Cooperative steady-state concentration calculation

[0157] ,

[0158] Meets occupational age requirements.

[0159] 4. Contribution Measurement and Evaluation Calculation

[0160] Total concentration reduction:

[0161] ① Source SSD reduction amount: ,

[0162] Contribution ②Total fresh air reduction: ,

[0163] Contribution .

[0164] ③Local exhaust reduction: ,

[0165] Contribution Verification: 80% + 4% + 16% = 100%, calculation is valid.

[0166] 5. Engineering optimization applications

[0167] The overall fresh air contribution rate is only 4%, and the fresh air volume is redundant throughout the entire area; Reduced to 200 m³ / h, recalculated. After slightly increasing the local exhaust ventilation to 600 m³ / h The standard was met, and daily ventilation power consumption was reduced by 21%.

[0168] Example 2: Three-stage synergistic design and energy consumption optimization assessment of benzene series compounds in a large automotive painting workshop:

[0169] 1. Basic parameters of site survey

[0170] The painting workshop was contaminated with a combination of benzene and xylene in its underground environment.

[0171] Total underground VOCs flux ;

[0172] Natural air infiltration ;

[0173] Uncontrolled benchmark concentration ;

[0174] Occupational Limits .

[0175] 2. Three-stage system design calculation

[0176] SSD baseplate negative pressure -12Pa, attenuation coefficient Remaining flux ;

[0177] Set global baseline A fresh breeze throughout the entire area:

[0178] ;

[0179] Workstation exhaust design:

[0180] .

[0181] 3. Calculation of Synergistic Concentration and Contribution

[0182] ,

[0183] Total cuts ,

[0184] ① Source SSD: ,

[0185] ②Comprehensive fresh air system: ,

[0186] ③Local exhaust ventilation: ,

[0187] The calculation is valid if the sum of the three is 100%.

[0188] 4. Optimize implementation results

[0189] The contribution of the overall fresh air is too high, resulting in redundant air volume. The overall fresh air volume was reduced to 1200 m³ / h, while the exhaust air volume at each workstation was increased to 3100 m³ / h. The concentration at each workstation was stabilized at 0.058 mg / m³, and the annual energy consumption of the ventilation system was reduced by 27%. This verifies the guiding role of the design formula and contribution evaluation model of this invention in optimizing energy conservation in engineering projects.

[0190] As can be seen from the above embodiments, the innovative aspects of the present invention—the three-stage collaborative control design for VOCs vapor intrusion into workshops in contaminated sites and the quantitative assessment method for single-point concentration contribution—are as follows:

[0191] Innovation Point 1: Constructing a standardized three-stage hierarchical collaborative design methodology

[0192] It pioneered a standardized three-level series design process: "source pressure reduction and blocking at the bottom plate, dilution of fresh air throughout the workshop, and local exhaust ventilation protection for operators' workstations." It provides quantitative calculation formulas for system parameters at each level, realizing an integrated design for three-layer progressive pollution control of underground intrusion, indoor areas, and personnel breathing points, filling the gap in complete treatment technology for contaminated sites in production workshops.

[0193] Innovation Point 2: Establishing a set of coupled steady-state analytical equations for underground gas infiltration and indoor ventilation.

[0194] Based on the conservation of pollutant mass, four core parameters are introduced: underground VOCs soil gas migration flux, negative pressure attenuation coefficient of the base plate, fresh air volume of the whole area, and exhaust air volume of the work station. A complete set of calculation formulas for concentration, air volume and negative pressure that can be directly used in engineering are derived. The system matching design can be completed without repeated CFD simulations, thus reducing the threshold for engineering use.

[0195] Innovation Point 3: Pioneering a quantitative assessment model for the contribution of multiple control measures to single-point VOCs concentration.

[0196] By using a unified mathematical framework to break down the concentration reduction into three categories of measures, and deriving formulas for calculating the contribution of source, overall, and local measures, the pollution control effects of different treatment methods at the same monitoring point can be quantitatively broken down. This allows for the accurate identification of inefficient units and guidance for system energy-saving optimization.

[0197] This invention provides a standardized design method for a complete system, along with a comprehensive quantitative evaluation formula system. It balances underground vapor containment with indoor respiratory safety, is easy to calculate, and highly practical. It can provide a standardized engineering tool for vapor intrusion control in polluting industrial plants such as chemical and coating plants, improve my country's risk management technology system for polluted sites, and reduce energy consumption and project design cycles. This invention also has the following technical effects:

[0198] (1) It pioneered a three-stage standardized complete design method with complete analytical calculation formulas, which is different from the existing single barrier and single ventilation scattered technologies. It provides a three-level unified design process of "source-whole area-workstation". All parameters are solved directly by relying on the steady-state mass conservation equation system, without the need for repeated CFD simulation calculations, which greatly shortens the design cycle of the pollution site plant treatment scheme and lowers the threshold for environmental and HVAC engineers.

[0199] (2) By coupling the boundaries of underground soil gas and indoor ventilation as dual pollution sources, and conforming to the actual working conditions of the production workshop, the existing technology of choosing one of the two to separate underground and indoor pollution sources, this invention incorporates the underground VOCs migration flux into the whole calculation system, accurately matches the continuous gas seepage in chemical, painting and other production workshops, and the air volume and negative pressure design results are more in line with the actual engineering, and the stability of treatment compliance is significantly improved.

[0200] (3) A multi-measure contribution quantification evaluation model is used to achieve quantitative breakdown of the governance effect. For the first time in the industry, a unified contribution calculation formula is given, which can accurately distinguish the pollution control contribution ratio of the bottom plate pressure reduction, full fresh air and local exhaust air, and intuitively identify redundant equipment and weak units. It provides quantitative data support for non-stop production transformation and system energy-saving optimization. Under the premise of meeting the same standards, the comprehensive energy consumption can be reduced.

[0201] (4) Adaptable to the policy requirements of "production and control at the same time" for domestic enterprises in production. The three-stage system can be constructed and put into operation in stages. The SSD base plate barrier can be modified in different areas. The ventilation system can be debugged in different areas. There is no need for the entire factory to shut down. It adapts to the treatment and transformation needs of a large number of existing polluting chemical enterprises in production in China and fills the gap in complete technology for this sub-segment.

[0202] (5) The model is highly versatile and compatible with various VOCs pollution plant formula system. It does not restrict the types of VOCs (benzene series, chlorinated hydrocarbons and petroleum hydrocarbons are all applicable). The workshop volume and equipment layout do not affect the calculation logic. Only the basic survey parameters need to be replaced to complete the design and evaluation. It can be widely used in various polluting industrial plants such as pharmaceutical, petrochemical, printing and electroplating, and meets the national standards of "Construction Land Soil Pollution Risk Control Standard" and "Occupational Exposure Limits of Hazardous Factors in the Workplace".

[0203] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A three-stage collaborative control design for VOCs vapor intrusion into a workshop at a contaminated site and a method for quantitative assessment of the contribution of single-point concentration, characterized in that... The invention includes a standardized design method for a three-stage hierarchical collaborative system and a quantitative evaluation method for the contribution of multiple control measures to VOC concentration reduction at a single point. The standardized design method for the three-stage hierarchical collaborative system specifically includes the following operational steps: Step S1. Site foundation parameter survey: S11. Obtaining total underground VOC migration fluxes through soil gas monitoring. ; S12. Determine the natural air leakage in the workshop using a closed-loop test. ; S13. Shut down all ventilation barriers and ensure the respiratory tract of personnel has no controlled baseline concentration. ; S14. Determine occupational exposure limits in the workshop. Mark the coordinates of all fixed operation stations; Step S2. Design and parameter calibration of the source SSD baseboard step-down system: S21. Flux decay formula based on pollutant mass conservation formula Attenuation coefficient calculation formula Calculate the target flux attenuation coefficient Match the negative pressure parameters of the base plate with the air volume of the soil air extraction fan; S22. The SSD baseboard voltage reduction system was run independently; the actual concentration at the corresponding workstation was measured. Verify the baseline concentration calculation formula when only SSD is enabled. The error between the calculated value and the actual measured value; Step S3. Standardized design of the workshop's comprehensive fresh air system: S31. Set the permissible background concentration for the entire workshop area. Substitute into the reverse design formula for global fresh air volume Calculate the minimum global fresh air volume ; S32. Turn off the SSD and the local exhaust system at the workstation, and run the general ventilation system alone. Measure the concentration at the workstation. Verify the formula for calculating the baseline concentration when only full fresh air is activated. Calculation accuracy; Step S4. Standardized design of local exhaust ventilation system for workstations: S41. Based on occupational limits To achieve the control target, the reverse design formula for workstation exhaust volume is substituted. Calculate the minimum exhaust volume for the workstation ; S42. Shut down the SSD system, ensure full ventilation, and operate the local exhaust fan separately to measure the concentration at the workstation. Verify the formula for calculating the baseline concentration when only local exhaust ventilation is activated. ; Step S5. Stable operation and coordinated concentration acquisition of the three-stage system: After simultaneously activating SSD, full fresh air system, and local exhaust system, and operating stably for 24 hours, the steady-state VOC concentration in the breathing zone of personnel was collected. The cooperative steady-state concentration satisfies the formula ; Step S6. Calculation of the contribution quantification of multiple measures: S61. Calculate the total reduction concentration of the three-stage system operating in coordination relative to the uncontrolled condition: ; S62. Calculate the independent concentration reductions under the three types of control measures respectively: Source SSD independent concentration reduction ; Comprehensive fresh air system independently reduces concentration ; Independent concentration reduction in local exhaust ventilation at workstations ; S63. Calculate the concentration reduction contribution of the three types of control measures respectively: Source SS contribution ; Comprehensive fresh air contribution ; Contribution of local exhaust ventilation at workstations ; S64. Verify constraints Determine the validity of the monitoring data and calculation results; Step S7. System load optimization and adjustment: S71. Iteratively optimize the parameters of the entire system based on the contribution values ​​of the three types of measures. If the contribution of a certain type of system is low, it indicates that the pollution control potential has not been released. Increase the fan air volume and the negative pressure of the base plate. S72. If the contribution of a certain type of system is too high, it indicates that the air volume is redundant. Reduce the fan power to lower the operating energy consumption. S73. Repeat steps S2 to S6 iteratively until the station's coordinated steady-state concentration is reached. Moreover, the entire governance system has the lowest overall energy consumption.

2. The method for three-stage coordinated control design and single-point concentration contribution quantification of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The basic parameter survey in step S1 includes surveying and obtaining the total underground VOC migration flux. (mg / h) Workshop natural air infiltration (m³ / h), baseline concentration at uncontrolled breathing points in the workshop (mg / m³), Workshop allowable occupational exposure limit (mg / m³), the fundamental formula for steady-state mass conservation under uncontrolled operating conditions: .

3. The method for three-stage coordinated control design and single-point concentration contribution quantification of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The source SSD system design in step S2: Calculate the VOCs migration flux attenuation coefficient (0~1), Formula for calculating residual VOCs flux: ， In the formula: — The remaining VOC flux entering the room after being blocked by SSD, mg / h; The pressure on the base plate increases monotonically; SSD system negative pressure matching calculation formula (calculating attenuation coefficient given target remaining flux): ， Match the negative pressure of the base plate with the air volume of soil gas extraction based on the target remaining flux.

4. The three-stage collaborative control design and single-point concentration contribution quantification method for VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The comprehensive fresh air system design in step S3: Workshop background concentration under conditions of SSD only on and full ventilation In the formula: — Background concentration in the workshop after full dilution, mg / m³ Inverse calculation of global fresh air volume (given) Solve ): 。 5. The method for three-stage coordinated control design and single-point concentration contribution quantification of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The design of the local exhaust ventilation system for the workstation in step S4: The final concentration of the three-stage system operating synchronously at the workstation: In the formula: — The final stable VOC concentration at the personnel respiratory monitoring point was mg / m³. The minimum workstation exhaust volume is calculated in reverse based on occupational limits (given occupational limits). Solve for the minimum ): .

6. The method for three-stage coordinated control design and single-point concentration contribution quantification assessment of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The method for quantifying the contribution of multiple control measures to VOC concentration reduction at a single point includes the following steps: (1) Calculate the workstation reference concentration when the single system is running independently, including: ① Only enable the source SSD (with general ventilation and local exhaust ventilation disabled) at the baseline concentration. : ； ② Only the baseline concentration is set when the full fresh air system is activated (SSD and local exhaust systems are disabled). : ； ③ Only local exhaust ventilation is activated (SSD off, general ventilation) to achieve the baseline concentration. : ； (2) Calculate the total reduction concentration of the three stages: ; (3) Calculate the concentration reduction independently for each of the three types of measures: ①Source base plate pressure reduction to independently reduce concentration : ② Comprehensive fresh air dilution and independent concentration reduction : ③ Independent reduction of concentration in local exhaust ventilation at workstations : ； (4) Calculate the concentration reduction contribution of each measure: ① Source SSD contribution : ②Comprehensive fresh air contribution : ③ Contribution of local exhaust ventilation : Constraint verification conditions: It is used to verify the accuracy of calculated and monitored data.

7. The method for three-stage coordinated control design and single-point concentration contribution quantification of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The assessment method consists of three control levels: source intrusion prevention and control layer, overall fresh air dilution layer, and local workstation protection layer.

8. The method for three-stage coordinated control design and single-point concentration contribution quantification of VOCs vapor intrusion into workshops in contaminated sites according to claim 1, characterized in that, The source intrusion prevention and control layer adopts a bottom plate pressure reduction SSD system to block the migration of VOC vapor from underground soil into the room; the overall fresh air dilution layer adopts a workshop displacement-type comprehensive ventilation system to dilute the background concentration of VOCs throughout the workshop; and the local workstation protection layer adopts an operator breathing belt directional local exhaust system to quickly remove pollutants from the core exposure areas of personnel.

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