Influence of Bark Content on Ash Melting Temperature

Abstract

One of the important fuel properties is ash melting. Fuel with high ash sintering is not applicable for most of the boilers. Sintering is the process that can occur in the burner and block air flow to the base fuel layer. One of the materials, which can participate on this process, is wood bark. The ash melting from combustion of wood bark has negative impact and lowers the temperature in the process. The melting temperature depends on the chemical composition of ash. Ash melting takes place in several stages: first sign of deformation is gradually melting until complete reflow. In order to analyze the melting process, the various stages are recorded with characteristic temperatures. These temperatures are defined as follow: deformation temperature “DT”, the sphere temperature “HT”, hemispherical temperature “HT” and the flow temperature “FT”. For reliable operation of boilers is important to know melting temperature of ash. Melting temperature for low meltable ashes is from 1000 to 1200°C, for medium meltable ashes from 1200 to 1450°C and for heavy meltable ashes over 1450°C. During the combustion of wood biomass the temperature should not exceed 1100°C. This article deals with ash content from combustion of wood bark and its ash melting.