Modelling the chemical recycling of plastic waste via pyrolysis and analysing integration with existing refinery infrastructure

Abstract: Current plastic management is unsustainable as large amounts of plastic end up landfilled or in the ocean, necessitating an expansion of waste management infrastructure. Pyrolysis is a viable chemical recycling option, and in this report a pyrolysis model is constructed in Aspen Plus. The model is a stoichiometric pre-sorted polyethylene feed and is based on experimental pyrolysis results. Products from the model include 19.6% production of LPG gas and 28% of fuels such as gasoline, kerosene and diesel. Char production was estimated to 9.5% and dechlorination achieved sufficient results with the addition of calcium oxide to the pyrolysis. Energy demands were estimated to be 1.77 GJ/hour for hot utility and 0.556 GJ/ hour for cold utility. A techno-economic analysis approximated capital costs to $13.5 million and annual net profits of $3.8 million annually, resulting in a payback time of 3.6 years. Finally integration opportunities with existing refinery infrastructure were investigated, showing that integration is feasible.