Effect of dynamic low DREs from flare combustion on regional ozone pollution during a chemical plant shutdown. (1st June 2021)

• Record Type: Journal Article
• Authors: Ge, Sijie; Wang, Sujing; Xu, Qiang; Ho, Thomas
• Is Part Of: Atmospheric environment. Volume 254(2021)
• Publication Date: 2021-06-01
• Subjects: Chemical plant shutdown -- Ozone pollution -- Flare emissions -- DRE -- CAMx -- Aspen Plus; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2021.118399
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The destruction and removal efficiencies (DREs) for industrial flare combustion could be, in reality, less than the supposed standard values of 98%/99% because of various atmospheric and plant operating conditions. Thus, flaring during chemical plant shutdown (CPS) under low DREs would release larger quantities of VOCs and NOx than expected, which might rapidly worsen the regional ozone pollution under solar radiation. Therefore, it is vital to examine the quantity and sensitivity of ozone impacts owing to low DREs for flare combustion rather than standard values. In this paper, effect of dynamic low DREs on regional ozone impacts during CPS flaring has been systematically conducted by coupling Aspen Plus with CAMx modeling and simulation. Case studies indicated that 8-hr ozone caused by CPS flaring under low DREs could range from 6.08 to 7.28 ppb, which was much greater than that based on the standard DREs ranging from 1.8 to 2.19 ppb. This study also demonstrated that the 8-hr ozone increment could be significantly reduced from the maximum of 6.14 ppb to the minimum of 0.85 ppb by starting the CPS operations at the optimal time. Another important finding was that ozone impacts might slightly increase with the increase of flare stack height due to meteorological conditions including high wind speed and strong solar radiation. This study would provide scientific support for quantitative ozone evaluation caused by CPS flare emissions, which will enrich future solutions for cost-effective regional air-quality management and ozone pollution control. Graphical abstract: Image 1 Highlights: Dynamic chemical process simulation was coupled with air-quality modeling. Ozone pollution was substantially underestimated with standard combustion efficiencies. 8-hr ozone can be largely reduced about 5.3 ppb by selecting the optimal time for flaring. Ozone impacts may slightly increase with the increase of flare stack height. Cost-effective and environmentally benign strategy was demonstrated for regional ozone control.