Process analysis of refuse derived fuel hydrogasification for producing SNG

Abstract

Toxic emissions from waste thermal treatments are a major issue that in several countries hinders a full waste cycle. This paper addresses the specific topic of a sustainable exploitation of the refuse derived fuel (RDF). Because concerns still arise when using RDF as fuel, a new approach for its exploitation, the RDF hydrogasification for producing synthetic natural gas (SNG), is discussed herein. The process has been simulated with Aspen code. The best operating conditions to maximize methane yield, under thermodynamic equilibrium conditions, have been studied while the composition of the obtained SNG has been verified in order to comply with the requirements of the methane grid. Furthermore, the analysis looked at the effect of the hydrogen excess in promoting the methane yield and the reduction of the dioxins formation. The energy analysis of the process, that has considered the use of commercial alkaline electrolysers for producing hydrogen, has been found to be mainly affected by the electric power consumption and has exhibited values of energy efficiency around 61%. Finally, a preliminary assessment of the economic competitiveness of this process has been done in order to clarify if the benefits from costs avoided for waste disposal could be the breakthrough in making RDF a sustainable competitive fuel. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.