Composition and Microstructure of Filter Ashes and Incrustations in a Lignite Boiler

Abstract

Abstract: The continuously changing and decreasing quality of lignite increases the tendency of fouling or slagging in lignite boilers. Investigations of the structure and composition of filter ashes and incrustations will make an important contribution to the understanding of their formation resulting in less corrosion and fouling of lignite power plants, especially for problematic fuels. This minimizes failures due to fouling, sintering and slagging of incrustations at the heat exchanger surfaces. The filter ashes consist of clay relicts, anhydrite, quartz and iron compounds. The incrustations are Fe-rich or aluminosilicate-based and show an inhomogeneous structure in CT (computer tomography). Both, dense and porous structural constituents can be identified, which suggests a shell-like structure due to the constant adhesion of softened or melted particles.