Fluidized-bed combustion technology was commercially introduced about a decade ago. It was one of the most promising approaches to fuel-efficient and environmentally sound steam generation in both industrial and utility applications.
Research and development of advanced fluidized-bed systems for power generation began when Foster Wheeler Corp. launched a research program in the early 1970s at its John Blizard Research Center in Livingston, N.J. (The company pioneered the use of fluidized-bed technology in the 1940s).
At the Blizard Research Center, numerous conceptual design studies defined the basic design parameters of fluidized-bed steam generators. These parameters were confirmed by testing in both hot and cold pilot plants.
This work provided the design basis for the world's first commercial fluidized-bed steam generator, commissioned at Georgetown University in 1979. Since then, the company has designed and started up 46 bubbling fluidized-bed steam generators.
During the 1980s, emissions regulations became more stringent, and circulating fluidized-bed (CFB) combustion emerged as the technology of choice for the industrial power-generation market. The reasons for this are:
- Lower sorbent usage for a given sulfur-recovery rate
- Higher combustion efficiency
- Lower NOx emissions through staged combustion.
Additionally, CFBs burn a variety of fuels, such as bituminous coal and gob, anthracite culm, lignitic waste, delayed and fluid petroleum coke, wood waste, shredded tires, and other waste fuels.
A CFB steam generator provides multistage combustion by circulating solid fuels with fluidizing air in a high furnace, resulting in combustion efficiency as high as 99%. The unburned solids are recirculated through a cyclone back into the furnace. Fans supply air to fluidize the bed and sustain combustion through induced and forced circulation.
More recently, Foster Wheeler Energy Corp. has researched the use of CFB technology in large-capacity units using the reheat-steam cycle in utility power generation. This research resulted in the development of the Intrex heat exchanger, and its introduction in the Nisco project.
Foster Wheeler Development Corp.-the company's research and development arm-is working on a second-generation circulating, pressurized, fluidized-bed combustion technology under U.S. Department of Energy funding. The advanced technology is expected to be significantly more efficient, achieve lower emissions, and result in lower-cost electricity.
Fluidized-bed technology allows industry to burn coal, coke, and other fluids-including waste fluids-more efficiently and with reduced emissions. Such characteristics are important in a world increasingly concerned with more-efficient use of natural resources and more-effective protection of the environment.
Copyright 1993 Oil & Gas Journal. All Rights Reserved.
