Dynamic simulation for flare minimization in chemical process industry under abnormal operations

• A systematic methodology for industrial flare minimization under abnormal operations.
• Safety considered plant-wide dynamic simulation for flare minimizations.
• Simultaneously benefit industrial and environmental sustainability.

Flare minimization (FM) in chemical process industry (CPI) under abnormal operating conditions such as plant start-ups, shut-downs, and process upsets can significantly reduce plant emissions, which suggests tremendous raw material and energy savings for plant, as well as substantial environmental and societal benefits. In this paper, a systematic methodology based on plant-wide dynamic simulation is presented for safety-oriented CPI FMs under abnormal operating conditions. Since off-specification emission sources are inevitable during abnormal operating conditions, to significantly reduce flaring emission in a chemical plant, they must be either recycled to the upstream process for online reuse, or stored somewhere temporarily for future reprocessing. Thus, the off-spec products could be reused instead of being flared. Together with the new development of FM operating strategies, rigorous dynamic simulation based safety checks are also highlighted in the presented methodology. Two case studies on FMs for start-up and shut-down operations of an ethylene plant have been employed to demonstrate the efficacy of the proposed study.