Chemical Engineering Science 62 (2007) 627 – 635 www.elsevier.com/locate/ces Combustion of refuse-derived fuel in a fluidised bed Francisco D. Hernandez-Atonal, Changkook Ryu ∗ , Vida N. Sharifi, Jim Swithenbank Department of Chemical and Process Engineering, Sheffield University, Mappin Street, Sheffield S1 3JD, UK Available online 15 September 2006 Abstract As a medium to maximise the resources recovery from municipal solid waste, refuse-derived fuel (RDF) is considered as a priority solution in industrialised countries. RDF is a value added material with a higher calorific value and a homogeneous particle size. The main objective of this study was to investigate the RDF combustion characteristics and the associated pollutant emissions in a fluidised bed combustor. A series of combustion tests was carried out using three different RDF samples in two atmospheric fluidised bed combustors (AFBC). The temperature profiles, gas composition and the properties of fly ash residues were investigated for different RDF fuels and operating conditions. Bed temperatures (ranging from 754 to 906 ◦ C) were correlated with different air and RDF feed rates. It was shown that the overall combustion efficiency of the system improved when secondary air jets were introduced into the system. Only between 2.6% and 4.3% of the potential nitrogen in the fuel was converted to NO x . A slight decrease in the NO x concentration was observed upon injection of secondary air. The capture fractions of N, Cl and trace elements in the fly ash were evaluated from the elemental composition of the fuels and fly ashes. The ratios of Ca/(S + 0.5Cl) between 1.6 and 2.2 proved to be very efficient in capturing Cl in the fly ash. The operating conditions of the AFBC system together with the physical characteristics of the ash allowed a full elutriation of the ash residues.  2006 Elsevier Ltd. All rights reserved. Keywords: Combustion; Fluidised bed; Refuse-derived fuel (RDF) 1. Introduction The current lifestyle in developed countries generates exces- sive amounts of waste. In the UK, 500 kg of wastes per capita are produced each year accounting to 30 million tonnes of mu- nicipal solid waste (MSW) per year (European Commission, 2005). This consuming society does not seem to curb its trend of massive waste generation. In many of these countries this waste is landfilled with important environmental implications. For this reason, not only the UK, but also many other countries are aiming to increase their use of alternative methods of MSW disposal, such as recycling, thermo-chemical conversion, and biological conversion. Waste incineration plays an important role in the waste man- agement as it is one of the most reliable and environmentally friendly thermal technologies when compared to landfill option. On top of this, the increased popularity of renewable sources ∗ Corresponding author. Tel.: +44 114 222 7523; fax: +44 114 222 7501. E-mail address: c.ryu@sheffield.ac.uk (C. Ryu). 0009-2509/$ - see front matter  2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.ces.2006.09.025 of energy due to the global warming concerns is placing waste and waste derived fuels in an important position in the energy sector. The term ‘refuse-derived fuel’ (RDF) has been used to com- mercialise many types of waste derived fuels. Typically, RDF refers to the segregated high calorific fraction of processed MSW. However, the term RDF does not have a recognised def- inition within Europe and therefore, it is not used consistently across the EU. For this reason, different fractions of the waste separated in both mechanical and MBT processes are labelled as RDF. Another term is also gaining popularity within the in- dustry in Europe: ‘solid recovered fuel’ (SRF). The term SRF is used to describe a fuel with tight quality specifications re- quired by the customer ( Archer et al., 2005). Thus, as a step forward to normalise the definition of waste-derived fuels, the EU is working on a formal classification system for SRF. To date, not many classifications of RDF have been recog- nised. However, in the EU various names are used for fu- els resulting from different fractions of MSW feed material (European Commission, 2003). Some examples are as follows: recovered fuel (REF), packaging-derived fuel (PDF), paper and