Experimental characterization of self-heating behavior of charcoal from eucalyptus wood

Abstract

The long cooling time of charcoal produced from eucalyptus pyrolysis is due in part to the heat generation in oxidation reactions at low temperatures. The intensity of this reactions depends on complex interactions between the interstitial gas and the solid matrix. The objective of this paper was to investigate the kinetics of the self-heating phenomena due to charcoal oxidation at low temperatures and at different oxygen concentrations. Samples of 230 g of charcoal were subjected to heating in a steel reactor at constant temperature, from 100 to 300 °C, and oxygen concentrations ranging from 20.9 to 10%. Was evidenced that the rate of oxygen consumption increases with charcoal temperature at rates that depend on the initial concentration of O2. The beginning of the oxidation reactions was observed at 67 °C in atmospheres with 20.9% O2. The overall activation energy for the self-heating phenomenon was 17,790 J mol−1 and its intensity was increased with the temperature and O2 concentration.