(245f) Scheduling for Multiple Chemical Plant Turnarounds to Minimize Regional Air Quality Impacts

During the chemical manufacturing process, multiple chemicals are released into the atmosphere including benzene(C₆H₆),carbon monoxide(CO), nitrogen oxides(NO_x), sulfur dioxide(SO₂), and volatile organic compounds(VOC_s ).Depending on meteorological conditions, emission quantity, and the fate and transport of chemical species, the environmental impact can affect air quality over a great area. This will cause the regional increased exposure to primary pollutants for neighboring populations with the summation of emission pollutant due to the temporal co-occurrence of start-ups and shutdowns among multiple chemical plants. Furthermore, these emission chemical will react with each other to form other secondary pollutants. The mechanism should follow the principle of reaction kinetics. Therefore, from the emission control point of view, the best practices for improving regional air quality should integrate both efforts on plant-wide emission minimization at every industrial point source, relationship and regional-wide multi-plant emission variability control.

In this paper, a scheduling methodology for coordinating multiple chemical plant start-ups is developed to minimize regional air quality impacts by the combination of reaction kinetics, atmosphere dispersion and scheduling will give the practical and feasible scheme to reduce primary and secondary pollutants in the region where multiple plants are co-located. The whole methodology will include two stages: proactive risk assessment and scheduling optimization. During the risk assessment, the focus is put on the changes in the weather conditions (stability class and wind condition), the pollutant and regional emissions from other sources, especially in the extreme weather or other emergent situations. The simulation result will indicate whether it needs to optimize the temporal sequence of multiple plants' activity. If necessary, the optimization modeling result will give an optimized temporal distribution of start-ups and shut-downs to reduce the chance of emission pairing and the concentration of primary and secondary pollutant. The development provide quantitative decision support for multiple stake holders, including government environment agencies, chemical industry, and local communities.