Quantitative in-situ measurements of sodium release from combusting South Australian brown coal particles

Abstract

The release of volatile sodium during coal combustian is a significant factor in the fouling and corrosion of heat transfer surfaces within industrial coal-fired boilers. In this paper, new measurements of sodium release from combusing South Australian brown coal particles are reported for the first time using a previously established method (van Eyk et al. 2008). By applying a chemical equilibrium model, at an appropriate location in the flame, the total sodium release is estimated from the measured atomic sodium concentration profile. In comparison to Victorian brown coals, these South Australian brown coals release sodium more rapidly and in larger absolute quantities. Using the data collected in this study, combined with previously collected data for Victorian brown coals, it is inferred that approximately 53% of water-bound sodium and approximately 100% of the organically-bound sodium is released following devolatilisation for both South Australian and Victorian brown coals. Further work is necessary to determine whether the mechanism and kinetics of sodium release that have previously been forumlated based on Victorian coals are applicable for thes South Australian brown coals.