Fluidized-Bed Firing Systems

Fluidized-bed combustion (FBC) is a leading technology for the combustion of a range of fuels, fossil and others, because of several inherent advantages it has over conventional combustion systems including fuel flexibility, low NOx, in situcontrol of SO2, excellent heat transfer, high combustion efficiency, and good system availability. The development of the fluidized-bed concept started in 1922 with the Winkler patent for gasification of lignite. The first major implementation of the concept was around 1940 in the chemical industry to promote catalytic reactions. This chapter discusses the two main FBC groups, atmospheric FBC and pressurized FBC, and the two minor subgroups, bubbling and circulating fluidized-bed. It presents a brief technology overview focusing on fluidization characteristics, heat transfer, fuel flexibility, emissions formation and control, and combustion efficiency. It also describes ash chemistry and agglomeration issues, and the role of FBC boilers in clean coal technology development in the United States and worldwide. Furthermore, it discusses unique opportunities for FBC technology, specifically a potential role in providing security to the food industry.