(562c) Flare Minimization for Ethylene Plant Startup Operation

Chemical plant startups usually have to flare huge amounts or off-spec product streams, and thus emit tremendous amounts of CO, CO2, NOx, and some hazardous volatile organic compounds (VOCs), which will cause severe air pollution problems and negative societal impacts. Meanwhile, flaring also cause lots of raw material and energy loss that could generate more desired products for the industry. Thus, flare minimization has great significance on environmental, societal, and economic advancement toward the sustainability of chemical process industry.

In this work, a plant-wide dynamic simulation based general methodology has been developed to addresses near-zero flaring for an ethylene plant startup operation. Since off-spec products are inevitable during the plant turnaround operation, they must be either recycled to the upstream process for online reuse, or stored somewhere temporally for future reprocessing when the plant manufacturing becomes stable. Therefore, the off-spec products can be saved instead of being flared. To reach the near-zero flaring target, different recycle designs and startup operation strategies are virtually tested through plant-wide dynamic simulations. The plant-wide dynamic simulation can identify benchmark allocations of flaring emissions during the plant start-up; it can also used to examine operation safety issues under different startup designs and operation procedures. Combined with the economic and environmental benefits analysis the developed methodology helps check the technology effectiveness of different flare endeavors.