(1) online monitoring
The main substances in the VOCs material of the device are monitored online through mass spectrometry. Monitoring points are arranged in a preferential way according to LDAR data analysis and fluid mechanics analysis of wind field in the production device. All-weather real-time online monitoring can timely detect the VOCs leakage of the equipment and control VOCs leakage from the source.
When manufacturing equipment involves hazardous air pollutants (HAPs) such as benzene, toluene, xylene and ethylbenzene, the system can monitor them online and take the contact limit required by the national occupational health standards of the Peoples Republic of China as the alarm threshold to ensure that the working environment of enterprise employees meets the occupational health requirements.
The mass spectrometer can set up the sample analysis of each circuit to analyze the concentration of different substances. When the production device is closer to the factory boundary, some monitoring points can be placed at the factory boundary to monitor benzene, toluene and xylene which have the requirements of the emission limit of the factory boundary. Other monitoring points can be used to analyze the main VOCs substances in the production device.
The system has the management function of monitoring substances, monitoring points, devices and leakage positions, original monitoring data and meteorological parameters, etc. are stored in the system platform, which can meet various requirements of different data volumes, data characteristics and query processing, as well as the functions of data recording, statistical summary and exporting reports.
Figure 12. System platform management function
(2) source traceability analysis
When the sampling point is detected to be leaking, real-time wind speed and direction data are confirmed through the meteorological parameter sensor, and the corresponding model of the wind field in the wind field hydrodynamics database is captured. The monitoring concentration values of nearby monitoring points were brought into the hydrodynamic model of the wind field, and the equipment or area where the leakage source was located was calculated through the traceability calculation model (inverse calculation model such as the monte carlo mulcaf chain and the renormalization algorithm).
(3) online early warning
Through the hydrodynamic calculation of the leakage source, combined with the wind speed and direction provided by the meteorological parameter sensor, the diffusion of the leakage is calculated, which is the pre-warning of the intended diffusion area. If the leaking substances are benzene, toluene and xylene, it is necessary to calculate by hydrodynamics whether the leakage exceeds the emission limit requirements of the factory boundary when it spreads to the factory boundary. When the leakage is detected, the source shall be traced and calculated in time, and the leakage diffusion shall be estimated, so as to achieve the function of timely online warning for the factory boundary and downwind area, so as to avoid personnel contact and other safety and environmental hazards.
(4) supervision and supervision
The system can help enterprises to supervise and monitor VOCs leakage, reduce emissions from the source, generate economic benefits, reduce potential safety hazards of production devices, respond to environmental monitoring requirements, protect employees occupational health, and benefit the health protection of nearby residents. At the same time, it can cooperate with environmental protection department environmental information disclosure and environmental law enforcement inspection.
