Life cycle assessment and optimization on the production of petrochemicals and energy from polymers for the Greater London Area

摘要

In this study, a life cycle assessment (LCA) approach is used to evaluate the best scenarios for the treatment of polymer materials and the production of petrochemicals and energy in the Greater London area. Different scenarios were examined and mathematical programming models were used to find an optimum solution which maximizes environmental benefits whilst minimizing costs (the objective function chosen in this study). The superstructure of the problem studied includes a dry materials recovery facility (MRF), an incinerator unit (IU) with combined heat and power (CHP) recovery, a low temperature pyrolysis reactor (LTP) and a hydrogenation (hydrocracking) unit. The objective function was set to include capital and operational and maintenance costs. Other costs such as transport, landfilling fees, transfer station costs and taxes, were also included. The main objective of the study was to identify the best recovery option against the traditional incineration process. Production of valuable petrochemicals and refinery products (i.e. syncrude, naphtha, heavy fraction (waxes), C3, C4, etc.) can be yielded when processing the plastic in a thermo-chemical reactor, hence increasing the overall process profitability. Revenues from packaging recovery notes, levy exemption and renewable obligation certificates were all included in the economic model. The benefit of producing combined heat and power was also investigated. The environmental impact of the different process options was evaluated in terms of emissions of CO2 and other pollutants (e.g. NO_x, PM_(10), CO, THC, SO2, etc).