System for Drying Coal Using Hot Circulating Water From Condenser RESEARCH DEMONSTRATES BENEFITS OF DRYING WESTERN COAL

Over the last several decades, the US electric utility industry has come to rely, increasingly, on Powder River Basin coals (PRB) and lignite for electric power generation. This increase in the use of these fuels stems, in part, from their being relatively inexpensive and low in sulfur. However, both types of fuel are high in moisture—25 to 40% for lignite and 15 to 30% for PRB – and this results in significantly lower boiler efficiencies and higher unit heat rates than occur with higher rank coals. The high moisture content can also lead to problems in areas such as fuel handling, grinding, and fan capacity. Research being conducted on lignite drying by the Energy Research Center for Great River Energy Corporation (GRE) shows that the value of lignite can be significantly enhanced and the quantities of stack emissions substantially reduced by reducing the amount of moisture in the lignite feedstock. Similar benefits are expected for PRB coal, if it is partially dried before it is burned. The Lehigh effort is headed up by Drs. Nenad Sarunac and Edward Levy; while Charles Bullinger and Mark Ness, who are with GRE’s Coal Creek Station, are in charge of the project for Great River. Coal Creek has two units with total gross generation exceeding 1,100 MW. The units fire lignite containing approximately 40 percent moisture and 12 percent ash. Both units at Coal Creek are equipped with low NOx firing systems and have wet scrubbers and evaporative cooling towers. According to Levy, “It is widely recognized that there are performance and operational penalties associated with using high moisture fuel. Despite this, the practice of thermal drying of coal is not in widespread use because of the perception that the cost of the drying process outweighs the benefits. One of the approaches being considered by Great River Energy, which we believe solves that problem, involves use of thermal energy from the hot circulating water leaving the condenser to provide the heat for drying.