Integrating Chemical Recycling into Brownfield Processes: Waste Polyethylene Pyrolysis and Naphtha Steam Cracking

In this study, we evaluate the economic and environmental impacts of integrating waste polyethylene (PE) pyrolysis with naphtha-based steam cracking for 660 Mt/y ethylene production. We compare six integration scenarios to both business-as-usual (BAU) steam cracking and greenfield waste PE pyrolysis plant. We perform process simulations and equipment design in Aspen Plus� V12, followed by a techno-economic analysis (TEA) and a life-cycle assessment (LCA. The integration capacity we considered corresponds to one full-capacity PE pyrolysis furnace, reducing naphtha feed by 7% in BAU steam cracking. Through the TEA, we identify the most cost-effective scenario by merging the PE pyrolysis gas with the steam cracker furnace outlet after preheating the PE feed. This integration reduces production costs by 6.46MM�/y, improving costs a 0.3% compared to BAU and 30% compared to the pyrolysis greenfield design. LCA results show that the greenfield pyrolysis plant achieves the lowest global warming potential (GWP), reducing emissions by 14% compared to BAU. Among the integration scenarios, lowest GWP occurs when PE pyrolysis gases, also with feed pre-heating, merge before the main compressor train, obtaining a 0.12% GWP reduction compared to BAU. This analysis highlights the potential of introducing circular technologies in existing plants to progressively shift from fossil fuel usage.