Coal

Fluidized beds competitive with conventional coal-fired units in electric power generation

Issue 1 and Volume 99.

INDEPENDENT POWER

Douglas J. Smith,

Senior Editor

Fluidized beds competitive with conventional coal-fired units in electric power generation

Dale Simbeck, vice president of technology, SFA Pacific, Inc., Mountain View, Calif., speaking at the recent Council of Industrial Boiler Owners` fluidized bed conference in Jacksonville, Fla., said that fluidized bed combustion (FBC) technology has now become a major competitor for conventional solid fuel combustion systems worldwide. Here in the United States independent power producers and cogenerators have led the way in deploying FBC boilers for electric power generation. Utility type reheat units of 115 MW to 165 MW are now in operation in the United States and Europe.

Worldwide, FBC plants over the last five years have routinely achieved 85 percent to 96 percent availabilities, according to Smith. FBC technology has demonstrated its commercial maturity and the vendors have scaled-up their designs with confidence. FBC units, ranging from 150 MW to 400 MW, are now being offered with full commercial guarantees, said Simbeck. Atmospheric bubbling and circulating FBC projects continue to dominate the market with bubbling beds accounting for 220 projects and circulating FBCs installed in 275 projects. Currently there are eight pressurized FBCs in operation or under construction.

Until recently the markets for fluidized bed technology have been in the United States, Western Europe and Japan. The United States, with 39 percent of the world`s FBC projects, has the largest number of projects. However, there is a growing interest in FBC technology in China, Eastern Europe, Southeast Asia, Korea, Israel and Turkey. India, because of the high ash content of its coals, and the need for expanded electric generating capacity, has the potential to be a major market for FBC technology in the future, according to Simbeck.

Although operating FBCs are primarily fueled by bituminous coal, the technology is also fueled by biomass and opportunity fuels such as coal wastes, petroleum coke and municipal wastes. According to Simbeck, coal and other solid fuels such as biomass, municipal solid waste, refuse derived fuel, and petroleum coke should continue to play a major role in the energy future of the United States into the middle of the 21st century. As a result, FBC technology should retain its niche in the solid-fueled technology mix.

However, Simbeck said that because of increasing constraints and evolutionary improvements in competing solids-fueled technologies, FBC no longer has the favored technology position that it once had during the boom days of the 1980s. In the future, FBC technology will have to compete with pulverized coal (PC) and stoker boilers equipped with flue gas desulfurization (FGD) and selective catalytic reduction (SCR) systems. Although PC-fired units with FGD and SCR may increasingly be the preferred boiler choice for high quality coals and for high-sulfur petroleum coke, circulating FBCs will remain a good choice for low-sulfur, low-rank (slagging/fouling) coals and low quality opportunity fuels. Over the next five to 10 years, Simbeck expects to see additional waste coal-fired congeneration projects in the United States.

The market for fluidized-bed technology looks promising. According to SFA, an increasing number of electric utilities are evaluating the technology, and by the year 2010 they expect to see a couple of 200-MW to 300-MW circulating FBC reheat units in operation in the United States. END

Steam capacity, Mlb/h Total Process Small District Pilot no. of Total primary Vendor Cogen steam power Utility heating plant units sold capacity, Mlb/hr