The K2SO4–CaSO4 system and its role in fouling and slagging during high-temperature processes

Abstract

Currently, there is an increasing interest to produce energy mainly from renewable sources such as biomass. However, fouling, slagging and corrosion threaten long-term operation availability and costs of biomass power plants. Alkali metal elements in the biomass fuel and the ash fusion behavior are the two major origins contributing to slagging during high-temperature biomass combustion. Accumulated slags decrease thermal efficiency of superheaters. These slags often constitute a considerable percentage of complex inorganic phases such as K2Ca2(SO4)3. However, thermodynamic properties of these inorganic phases and their combined effect, which would help to solve the fouling, slagging and high-temperature corrosion related problems in biomass combustion processes, are not well known. In the present work, thermodynamics and phase equilibria of selected phases in the K2SO4–CaSO4 system were both critically reviewed and experimentally studied. The obtained results are presented and discussed.