1 The combustion of solid paraffin wax and of liquid glycerol in a fluidised bed A. Menon a , N. Waller a , Wenting Hu b,c , A.N. Hayhurst a *, J.F. Davidson a , S.A. Scott b a Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke St, Cambridge CB2 3RA, England b Department of Engineering, University of Cambridge, Trumpington St, Cambridge CB2 1PZ, England c Now at: School of Chemical Engineering and Advanced Materials, Newcastle University, Newcastle NE1 7RU, UK * Corresponding author, Tel.: + 44 1223 334790; fax: +44 1223 334796 E-mail address: anh1000@cam.ac.uk (A.N. Hayhurst) HIGHLIGHTS  In a hot bed of alumina sand, fluidised by air, paraffin wax burns like a plastic  When wax is fed on top of a bed, at least half its carbon-content ends up as soot  If wax is fed low down such a bed, no soot is produced – only CO or CO 2  If glycerol enters low down a bed, it burns to CO or CO 2 , without soot appearing  Bubbles of fuel and air burn in a bed > 800 o C, but explode above a cooler bed ABSTRACT Two fuels were burned in electrically heated beds of alumina sand, fluidised by air. The fuels were: (i) paraffin wax, which is a solid containing 100% volatile matter and (ii) glycerol, a liquid, whose potential as a fuel needs assessing. The bubbling fluidised beds were held in the range 400 - 900 o C. Pieces of paraffin wax burned like a plastic, so when fed on top of a bed, the wax floated and generated clouds of soot. Soon, it then sank into the bed. When the sand was below ~ 800 o C, combustion occurred noisily in exploding