Cofiring Tire-Derived Fuel With Coal

Tires provide a resource of significant interest to many utilities. Tires—and tire-derived fuel (TDF)—have a high calorific value along with other favorable fuel characteristics. At the same time they present material preparation and handling issues for fuel users. For environmental reasons, they are more difficult and costly to dispose of in landfills. In 1990, only 25 million tires or 11% of the annually generated scrap tires in the U.S. were utilized (recycled, retreaded, and burned for energy). In 1994, this number increased to 138 million tires or 55% of the annually generated scrap tires with the largest increase due to tires used for energy (101 million tires). With an estimated number between 1–3 billion tires in stockpiles throughout the United States, this potential energy source is enormous. This paper will review several commercial demonstrations of tire-derived fuel cofired with coal in industrial and utility furnaces. Included will be discussions on fuel characteristics, preparation and handling of the tire-derived fuel, methods of utilization of the cofired fuel including appropriate combustion systems (e.g., cyclone boilers, stokers, fluidized bed boilers) and environmental results of the cofiring demonstrations.