(494a) Study on Regional Air-Quality Impacted By Chemical Plant Shutdown Under the Lower Destruction and Removal Efficiency for Flare Combustion

Flaring is a necessary measure for chemical plant safety. However, the industrial flaring generates large amounts of VOC and NOx, which could transiently aggravate regional ozone concentrations that could affect on human health and the air-quality. Currently, the national standard value of 98% or 99% for destruction and removal efficiency (DRE) is regulated and presumed for industrial flaring operations. In reality, the DRE value, however, could be lower than the national standard under various atmospheric and operating conditions, such as the high wind-speed and flare jet velocity. Thus, it is important to know the quantity and sensitivity of the regional ozone impact due to the lower DREs rather than standard values. In this paper, plant-wide dynamic simulations for plant shutdown flare emissions with regional air-quality modeling were coupled together to quantify the air-quality impact due to the lower flaring DREs caused by wind-speed and flare jet velocity. Firstly, the DRE formulas considering wind-speed and jet velocity were derived based on available references. Secondly, the shutdown flare emissions were estimated based on the DRE formulas and then inserted into emission inventory for air-quality modeling and simulation. After that, comprehensive air quality model with extensions (CAMx) based air-quality modeling was conducted to simulate the regional ozone increment due to the lower DRE values. This study could provide valuable and quantitative support for all relevant stakeholders, including environmental agencies, regional plants, and local communities.