The combustion of liquids and low-density solids in a cenospheric fluidised bed

Abstract

A fluidised bed of low-density (<0.9 g/cm3) hollow microspheres (cenospheres) was used for the combustion of selected liquid and solid fuels. It was proven that with such a fluidised bed, these materials burned inside the bed, not on its surface. For the purpose of some experiments the cenospheres with a nanometric, catalytic layer of iron oxide was prepared by original method using fluidised bed and Fe(CO)5 as a Fe2O3 precursor. The combustion was examined in the temperature range of 400–700 °C. When the inert fluidised bed was heated to 700 °C, ∼90% of the carbon of the degraded samples reacted to CO2 (93% for paraffin wax, and 84% for paraffin oil and glycerol). When the process was performed in the catalytic bed, ∼90% of the conversion to CO2 of the carbon contained in glycerol and paraffin fuels was achieved at 500 °C. The acoustic analysis confirmed that combustion takes place either just in the bubbles (inert bed) or both on the surface of particles and in the bubbles (catalytic bed). The analysis of acoustic signals showed that the explosions occurring in the bed do not form a deterministic pattern.