DryFining™ ~ Increases Plant Efficiency & Reduces Emissions

Great River Energy is pleased to announce commercialization of DryFining™. This world class technology is designed to refine or beneficiate the value of lignite coal through a drying and segregation process. The DryFining™ system was placed into service in December 2009 – following a major retrofit at its Coal Creek Station in Underwood, N.D.

U.S. Department of Energy partnership

Great River Energy developed the technology in partnership with the U.S. Department of Energy (DOE). The Dryfining™ system was selected in round one of DOE’s Clean Coal Power Initiative in 2003. The initiative focused on commercial-scale technology demonstrations to continue and expand the use of coal as a fuel source.

The DOE project included the testing of a 115-ton prototype dryer that supplied up to one-sixth of the coal for Coal Creek Station’s unit 2. The prototype unit dried and segregated the lignite before it entered one of eight pulverizers that feed lignite to the boiler. The project was successful in increasing boiler efficiency and decreasing stack flow, which reduces emissions.

Based on those results, DOE and Great River Energy announced a full scale commercial demonstration of the coal refining project in late 2006. The project included the final design and construction of a complete set of four modules for unit 2. Due to the success of the initial prototype results, Great River Energy expanded beyond the scope of the DOE project by building four additional modules for Coal Creek’s unit 1.

Benefits of Dryfining™

Coal Creek Station, like many power plants throughout the world, uses lignite coal to generate electricity. Lignite is considered a low-rank coal, due in part to its high moisture content. The coal drying component of DryFining™ reduces the moisture content by 10 percent. As of December 2009, the DryFining™ system was placed in service to supply refined lignite coal-called DryFine™ – to Coal Creek Station.

“Through research, we also learned that our process separates particles by density. That means that a significant amount of higher density compounds containing sulfur and mercury can be sorted out and returned to the mine, rather than oxidized in the boiler,” said Charlie Bullinger, senior principal engineer at Great River Energy’s Coal Creek Station.

This dried and segregated coal has a significant impact on improving power plant operations at Coal Creek Station. Through the system, the energy content of the lignite is being increased from 6,200 to 7,100 Btus per pound. This will reduce fuel input into the boilers in both units by about 14 percent by weight. In turn, this will increase overall power plant efficiency by 2 to 4 percent. It will also reduce stack emissions significantly – sulfur dioxide and mercury by more than 40 percent, nitrogen oxide by more than 20 percent and carbon dioxide by 4 percent!

Use of technology worldwide

Great River Energy has partnered with WorleyParsons to make this technology available to the global marketplace. As part of that partnership, WorleyParsons manages technology licensing for DryFining™ and will work with utilities interested in using the patented process to realize the dramatic efficiency improvements and emissions reductions observed at Coal Creek Station. DryFining™ will reduce the moisture content of and may beneficiate impurities contained in any low rank, high-moisture solid fuel. Thus, this innovative technology, developed in North Dakota, will be contributing to cleaner and more efficient power plants worldwide.

Benefit to cooperative members

The DryFining™ system offers significant operating benefits for Coal Creek Station. This immediately translates into benefits for Great River Energy’s cooperative members. “The project is part of a larger, long-term strategy designed to lower costs and improve our environmental performance, while developing new technology and innovation to benefit the fossil fuels industry”, said David Saggau, president and CEO, Great River Energy.

About Great River Energy

Great River Energy is a not-for-profit cooperative which provides wholesale electric service to 28 distribution cooperatives, including Arrowhead Electric Cooperative, Inc in Minnesota and Wisconsin. For more information, visit www.GreatRiverEnergy.com.

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