Aspen modelling and life cycle assessment of the gasification of DKR 350 plastic waste

Abstract

The Netherlands is frontrunner in the European Union in recycling plastic waste, employing mechanical recycling for 45% of the waste stream while incinerating the remaining 55% with energy recovery. The share which currently not recycled are mostly mixed and contaminated plastics. Mechanical recycling requires a mostly pure and uncontaminated input and is therefore not well-suited for handling the remaining plastic waste flow. Gasification, on the other hand, is a chemical recycling technique which is better suited for handling streams of contaminated plastics. Despite its potential, modelling of plastic waste gasification is still in its infancy. Furthermore, no life cycle assessment (LCA) research had been conducted evaluating the influence of reactor parameters on the global warming potential (GWP) associated with this process. This thesis aims to bridge the gap by further developing and validating an Aspen Plus model and using it to address the following research question: “What is the global warming potential of gasifying DKR 350 plastic waste compared to incineration in the Netherlands and what are the key reactor parameters that influence this impact?” Based on the LCA results, the study reveals that gasification of DKR 350 plastic waste in the Netherlands has approximately half the GWP impact of incineration. Furthermore, increasing the reactor parameters steam to feedstock ratio and equivalence ratio exacerbates the GWP impact, indicating the importance of optimizing these parameters. The reactor parameters ‘air on the riser’ and temperature show minimal influence on GWP. However, the conclusions drawn from the LCA are subject to inaccuracies stemming from the Aspen model. Recommendations are proposed to enhance the accuracy of both the Aspen model and the LCA, enabling verification and increased significance of the results. Future research should focus on obtaining additional experimental data to improve the accuracy of the Aspen model, while keeping in mind that the purpose of modelling is to supplement and reduce the required experimental research.