Air-Quality Conscious Scheduling for Multiple Olefin Plant Start-Ups

The ground-level ozone is a pervasive air pollutant, which can be formed from flare emissions during chemical plant start-up operations.  Especially in the concentrated industrial areas, the regional air quality (i.e., the ozone concentration) might be aggravated by simultaneously start-up emissions from multiple chemical plants.  Thus, it is environmentally important for optimal scheduling of multi-plant start-ups under their manufacturing allowances to minimize the possible adverse air-quality impact.  A systematic methodology on air-quality conscious scheduling for multi-plant start-ups has been developed.  It demonstrates that multi-plant start-ups without any coordination could result in the significant air-quality impact.  However, an optimal scheduling plan with several-hour tuning on the starting time of their start-up operations would significantly reduce about 80 % ozone increment.  The study couples process dynamic simulation for industrial flare emissions with regional air-quality modeling together.  It can provide valuable and quantitative supports for all relevant stakeholders, including environmental agencies, regional plants, and local communities.