Four Years of Operating Experience with DryFining Fuel Enhancement Process at Coal Creek Generating Station

摘要

Lignite and sub-bituminous coals from western U.S. contain high amounts of moisture (sub-bituminous: 15 to 30%, lignites: 25 to 40%). German and Australian lignites (brown coals) have even higher moisture content, 50 and 60%, respectively. The high moisture content causes a reduction in plant performance and higher emissions, compared to the bituminous (hard) coals. Despite problems associated with their high-moisture content, lignite and sub-bituminous coals from the Western U.S. and worldwide are attractive due to their abundance, low cost, low NO_x and SO_x emissions, and high reactivity (high combustion efficiency). A novel low-temperature coal drying process employing a fluidized bed dryer (FBD) and waste heat was developed in the U.S. by a team led by Great River Energy (GRE). Demonstration of the technology was conducted with the U.S. Department of Energy (DOE) and GRE funding at Coal Creek Station Unit 1. Following the successful demonstration, the low-temperature coal drying technology was commercialized under the trade name DryFining fuel enhancement process and implemented at both units at Coal Creek Station. The coal drying system at Coal Creek has been in a continuous commercial operation since December 2009. Four years of operating experience are described in this paper.