Single particle and packed bed combustion characteristics of high ash and high plastic content refuse derived fuel

Abstract

This work reports fundamental combustion characteristics of high ash (∼ 18 %), high plastic (30–35 %) content refuse derived fuel (RDF) pellets produced currently in India. Single particle and packed bed studies of RDF were carried out to quantify RDF combustion times and RDF ash fusion behavior, respectively. Single particle studies concluded that RDF has glowing time to flaming time ratio of ∼ 3.5, which was similar to that of biomass and four times lower than that of coal. It was also observed that unlike biomass, upon heating, RDF particle showed a unique 5.6 to 10.3 % swelling behavior due to the melting of plastic. Packed bed experiments at different air mass flux on RDF pellets concluded that apart from air mass flux, ash content plays a decisive role on rate of flame propagation. The high plastic content of fuel increased ash fusion tendency inside the packed bed. Packed bed studies suggested maximum superficial velocity of ≤ 0.03 m s−1 to avoid clinker formation. Sieve analysis of RDF ash collected from packed bed studies reported soft ash at a lower air mass flux and bigger lumps of fused ash at higher air mass flux. Clinkers obtained at different air mass flux 0.02, 0.07, 0.13 kg m−2 s−1 were 1 %, 8 % and 11 % of the feed, respectively.