Lessons from a Fatal Reboiler Rupture -- Preventing Incidents through Effective PSM Programs (CSB Williams Geismar Olefins Plant Investigation)

Ground-level ozone is a pervasive air pollutant, which can be potentially aggravated by flaring emissions from olefin plant shutdown operations. Although, flaring is crucial to chemical plant safety, the excessive flaring, for instance the intensive flaring from plant shutdown operations, emits huge amounts of ozone pollution precursors (VOCs and NOx). This will cause tremendous industrial material loss and environmental damage; meanwhile result in potential adverse impact to the regional air quality. Thus, the plant shutdown flare emissions should be minimized at any possibility. In this paper, plant-wide dynamic simulations for flare emissions with regional air-quality modeling are coupled together to quantify the air-quality impact and investigate potential opportunities to mitigate the adverse air-quality impact during plant shutdown operations. It proposed a systematic methodology on air-quality conscious study for shutdown operations of an olefin plant. Through studies of original and optimal cases, it shows that the original plant shutdown operation procedure has a serious and negative effect on the regional air quality; however, the optimal shutdown operation procedure would significantly reduce such impact together with the saving of tremendous emission sources. This study can provide valuable and quantitative supports for decision makings involving multiple stakeholders, including environmental agencies, regional plants, and local communities.