A review of experience of wastage in fluidized-bed boilers

Abstract

Fluidized-bed boilers based on variants of bubbling bed, circulating bed and pressurized designs are in wide commercial use in a range of sizes, and burn a variety of fuels. There is experience of localized metal loss on the fireside circuit of these units with some experiencing none while others, often of identical design, required urgent attention to allow acceptable operating periods. Nevertheless, wastage by combinations of corrosive attack and wear has not proved to limit significantly the application of this technology but, in some cases, has resulted in a heavy maintenance burden. In this paper, the current experience of such fireside wastage is reviewed, and the practical measures adopted to combat it are examined together with the apparent causes of the wastage. A review of the current state of mechanistic understanding of the causes of wastage suggests that understanding is developing slowly, partly because of the large number of variables involved. Mechanism-based solutions to the wastage problems still appear to be a useful goal, since they would reduce the maintenance costs associated with wastage, and improve the competitive position of fluidized-bed boiler technology.

Keywords:

• fluidized-bed boilers
• wastage