(529a) The Study of Ozone Pollution Superposition Caused By Simultaneous Olefin Plant Startups

It is indisputable that flare emissions from olefin plant turnaround operations generate large amounts of ozone precursors (NOx and VOCs) that will potentially aggravate the ground-level ozone pollution. In an industrial area where chemical and petrochemical plants are heavily populated, flare emissions can come from multiple plants in different spatial locations with different time periods. Thus, it is important to know the synergistic effect on ozone generations caused by flare emissions from simultaneously turnaround operations of multiple olefin plants in an industrial area. In this paper, a systematic methodology to study the ozone pollution superposition caused by simultaneous olefin plant start-ups has been developed. It couples dynamic start-up flaring profiles from multiple olefin plants and regional air-quality modeling together to examine the linearity and nonlinearity of ozone superposition. Based on our case studies, the synergies of ozone pollution due to multiple olefin plant start-ups cannot be simplified as the linear superposition. Meanwhile, the superposition nonlinearity has strong relations with the starting time of plant start-ups operations as well as the difference of plant distances. The general ozone superposition trends under different starting time and plant distance are also disclosed. Based on our study, the ozone superposition gradually approaches the linearity with the starting time of plant start-up operations changes from 00:00 to 10:00. In comparison to plant distances, the ozone superposition at about 32 km can be approximated as the linearity, and such linearity will decrease along with the decrease of plant distance. This study will be helpful to understand the ozone impacts from industrial point sources and identify cost-effective emission control strategies.