Agglomeration of the Bed Material in Fluidized Bed Reactors for Thermal Conversion of Biomass - A Threat for the Development of the Technology

Thermal conversion of biomass in fluidized bed systems for the production of heat and power and in the future also transportation fuels for vehicles through a gasification process need supply of biomass from various sources. These biomass fuels can vary a lot in quality and quantity. Many biomass types and waste derived fuels contain salts of alkali metals, i.e. potassium and sodium salts. When these alkali metals are released during combustion in fluidized bed systems using a bed material such as silica sand, agglomeration of the bed material may occur during unfavorable conditions. Thus, a significant amount of work has been put into the investigations of sintering mechanisms and the development of methods to prevent bed material sintering. In the present work combustion of alkali metal rich fuels alone and in combinations has been studied in the 12 MWth circulating fluidized bed (CFB) boiler located at the campus area of Chalmers University of Technology