And so to fluid-bed

The government push for coal conversion while retaining high air quality standards has focused new attention on fluidized-bed-combustion (FBC) boilers, which eliminate sulfur dioxide emissions and produce an ash that could be used for landfill or low-grade fertilizer. Operating at lower temperatures, the boilers also have acceptable levels of nitrogen oxide emissions. The fluidized-bed-combustor uses air to keep pulverized limestone and coal in suspension during combustion. Boiler tubes pick up heat from the molten cloud and achieve a higher efficiency than conventional boilers with scrubbers. Commercial feasibility of the concept has yet to be proven, although the first sale was made recently by Woodhall-Duckham to the Ohio Energy Resource and Development Agency. Other companies are exploring the possibility of FBC in areas where only high sulfur coal is available. Critics express doubt about potential corrosion of the boiler tube and floorbed and question whether the system can be scaled up or will be confined to small-scale applications. Potential users will be watching the results of ERDA demonstration projects. (DCK)