Coal Drying Technology Captures, Reuses Waste HeatA technology for coal-fired power plants dubbed "DryFining" improves fuel quality, decreases volatile gas emissions, and reduces a plant’s operating expenses and maintenance costs. A combination of drying and refining, the fuel-enhancement technology simultaneously dries and refines lignite, a form of coal that is softer and contains more moisture. Lignite is ordinarily burned as it is mined, but its water content causes it to produce a lower quality fuel.

Jeff Morris, vice president at Pittsburgh-based Heyl & Patterson, co-wrote and presented a paper on one installation with electric service provider Great River Energy and construction contractor WorleyParsons.  "Application of the DryFining Technology at Existing Power Units Firing Low-Rank Coal" was presented as a part of the advanced control technologies track at the 16th Annual Energy, Utility and Environment Conference (EUEC), which was held January 28-30 in Phoenix.

Heyl & Patterson custom-engineered a series of fluid bed dryers for the project, which use waste heat from the plant’s existing processes rather than a primary fuel, to gently dry the lignite and cause it to burn cleaner and more efficiently. The drying process also reduces gases such as carbon dioxide and removes compounds containing sulfur and mercury, making the fuel less volatile and of higher quality.

The alternative would be to add to existing emissions control equipment, incurring capital and operating expense and driving up the cost of power to consumers.

According to Heyl & Patterson in its blog, this technology has potential for other power plants throughout the world to become cleaner and more efficient. In the United States alone, 35 power plants burn lignite, and an additional 250 plants burn other types of coal with high moisture content. If used by new and existing power plants, this technology could reduce air emissions.