Supplementary firing of tire-derived fuel (TDF) in a combination fuel boiler

Each year in the United States, we dispose of nearly 240 million used tires. The tires are made of oil, carbon, and steel---three valuable commodities. The possibility of using tires as a fossil-fuel supplement in stoker boilers was first explored during the worldwide oil crisis of the early 1970s TDF was initially tested in paper mills in the Pacific Northwest. Since that time, TDF has been used by paper mills and cement kilns all across North America. Inherent high heat value and low moisture content make TDF a suitable fuel to burn along with wood waste. With a volatile-to-fixed-carbon ratio of more than 2 to 1, TDF provides quick heat release to help offset the 40--55% moisture in wood waste. During the past 15 years, paper mills across the country have used TDF as a wood-waste supplement to stabilize operation of combination-fuel boilers. This paper demonstrates and quantifies the benefits of TDF as a supplementary fuel in a combination-fuel boiler.