Ash transformation in suspension fired boilers co-firing coal and straw: Final report, PSO-Eltra 4766

In this literature report is provided a status for the present knowledge level on ash properties when co-firing coal and biomass. The fly ash formed in boilers using co-firing of coal and straw do have a large influence on ash deposit formation, boiler corrosion, fly ash utilization and operation of flue gas cleaning equipment. This survey includes discussions on the inorganic constituents transformation during straw and coal combustion, alkali-ash and alkali sulfur reactions, a survey of power plant and test rig co-firing experiments, a discussion of equilibrium calculations, a discussion of alkali getter experiments and a discussion of modeling of alkali reaction with kaolin. Presently there is still a need for a better understanding of especially the reaction of potassium with coal ash, thereby making better predictions of co-firing ash properties.