Pyrolysis and Gasification of a Real Refuse-Derived Fuel (RDF): The Potential Use of the Products under a Circular Economy Vision

Refuse-Derived Fuels (RDFs) are segregated forms of wastes obtained by a combinedmechanical-biological processing of municipal solid wastes (MSWs). The narrower characteristics,e.g., high calorific value (18-24 MJ/kg), low moisture content (3-6%) and high volatile (77-84%) andcarbon (47-56%) contents, make RDFs more suitable than MSWs for thermochemical valorizationpurposes. As a matter of fact, EU regulations encourage the use of RDF as a source of energy inthe frameworks of sustainability and the circular economy. Pyrolysis and gasification are promisingthermochemical processes for RDF treatment, since, compared to incineration, they ensure an increasein energy recovery efficiency, a reduction of pollutant emissions and the production of value-addedproducts as chemical platforms or fuels. Despite the growing interest towards RDFs as feedstock,the literature on the thermochemical treatment of RDFs under pyrolysis and gasification conditionsstill appears to be limited. In this work, results on pyrolysis and gasification tests on a real RDF arereported and coupled with a detailed characterization of the gaseous, condensable and solid products.Pyrolysis tests have been performed in a tubular reactor up to three different final temperatures(550, 650 and 750 C) while an air gasification test at 850 C has been performed in a fluidized bedreactor using sand as the bed material. The results of the two thermochemical processes are analyzedin terms of yield, characteristics and quality of the products to highlight how the two thermochemicalconversion processes can be used to accomplish waste-to-materials and waste-to-energy targets. TheRDF gasification process leads to the production of a syngas with a H2/CO ratio of 0.51 and a tarconcentration of 3.15 g/m3.