State of Fluidized Bed Combustion Technology

A new combustion technology has been developed in the last decade that permits the burning of low quality coal, lignite and other fuels, while maintaining stack emissions within State and Federal EPA limits. Low quality fuels can be burned directly in fluidized beds while taking advantage of low furnace temperatures and chemical activity within the bed to limit SO2 and NOx emissions, thereby eliminating the need for stack gas scrubbing equipment. The excellent heat transfer characteristics of the fluidized beds also result in a reduction of total heat transfer surface requirements, thus reducing the size and cost of steam generators. Tests on beds operating at pressures of one to ten atmospheres, at temperatures as high as 1600oF, and with gas velocities in the vicinity of four to twelve feet per second, have proven the concept. Early history of this technology is traced, and the progress that has been made in the development of fluidized bed combustion boilers, as well as work currently underway, in the United States and overseas, is reviewed. Details on the fluidized bed boiler installations at Alexandria, Virginia (5,000 lbs/hr), Georgetown University (100,000 lbs/hr), and Rivesville, West Virginia (300,000 Ibs/hr) are presented, and test results are discussed. Potential application of fluidized bed boilers in industrial plants using lignite and lignite refuse is examined. The impact of proposed new DOE and EPA regulations on solid fuels burning is also examined