Study of Dendromass Ashes Fusibility with the Addition of Magnesite, Limestone and Alumina

Abstract

The fusibility of ash from woodchip combustion is characterised in the present work. The impact of the increase in MgO, CaO, and Al2O3 content in the bio-ash on the classification of ash into categories according to slagging and fouling indices was evaluated. The ash was characterized based on the chemical composition using slagging and fouling indices. However, these ash composition changes did not assign the ash into categories of the indices FU, SR, RS, and B/A (fouling, slagging, slag viscosity, basicity), with less ash inclination to slagging and fouling. The indices were primarily derived for ashes from coal combustion. The indices values characterizing the ash were compared with measured results of ash melting according to STN ISO 540. The measured ash fusibility values showed that the addition of magnesite, limestone, and alumina to dendro-ashes increases the DT (temperature of deformation), HT (temperature of hemisphere), and the AFI (ash fusibility index). There is no conformity between the values of the indices and the measurement of ash fusibility temperatures. In terms of temperatures in the combustion chamber, the measured sintering (Tsin) and DT are suitable for evaluating the tendency of ash to slagging and fouling as well as an accretion of ash particles sticking to the lining.