Coal Drying

Pulverized coal-fired power plants which fire high-moisture coals generally operate with reduced efficiencies and increased stack emissions due to the impacts of high fuel moisture on stack heat loss and auxiliary power. The Energy Research Center (ERC) is part of the team of research organizations, led by Great River Energy (GRE) which developed a low-temperature fluidized bed coal drying technology for use in coal-fired power plants. This project was part of the US DOE’s Clean Coal Power Initiative. A feasibility study was performed at the ERC using a laboratory-scale fluidized bed dryer, followed by tests, led by GRE, in a pilot-scale coal drying facility, and then by design, fabrication and testing of a full-scale commercial drying system at GRE’s Coal Creek Station in North Dakota. Commercial systems installed at both units at Coal Creek include fluidized bed dryers, coal crushers, material handling equipment and particulate control systems

One of the unique aspects of this technology is that it provides for coal drying, using waste heat from the unit, and coal refining, by segregation of high-density coal ash particles from the rest of the coal during the drying process.  The technology has demonstrated benefits of increased coal heating value, coal and flue gas flow decrease, reduction in auxiliary power, and improvements in net unit heat rate.  Additionally, emissions measurements carried out at Coal Creek have indicated the added benefit of SO2, NOx and mercury emissions reduction, as well as reduction of CO2.  The coal drying demonstration project was named the 2010 Coal-Fired Project of the Year by the editors of Power Engineering magazine.  GRE’s coal drying technology is commercially available under the trade name DryFining™.  Nearly one-third of the electric power generated by coal in the US comes from plants that burn high-moisture coals, making this an important technology for efficient conversion of coal to power.

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