Mechanisms of deposition formation during biomass combustion

During the combustion of herbage-grass (hay), miscanthus and straw in a grate furnace, intensive deposit formation was observed on the combustion chamber walls (brick) and on the boiler walls (steel). Although it is obvious, that the deposits are caused by the fly ash, the formation mechanisms of depositions are not yet known in detail. The aim of the present investigation was to analyze the chemical and morphological properties, to identifiy the mechanisms of deposition formation, and to propose measures for deposition reduction. Depositions from biomass are accumulations of fine particles in the nanometer range, whose chemism is dominated by the properties of potassium chlorine, the major compound found in the deposition. Among the known formation mechanisms, thermophoresis revealed to be the crucial process for depositions from biomass combustion.