AN ENVIRONMENTALLY SOUND PROCESS FOR UTILIZING WASTE TIRE-DERIVED FUEL AND RAILROAD-TIE-DERIVED FUEL IN COAL-FIRED STOKER BOILERS

THE UNITED STATES HAS A LARGE BACKLOG OF WASTE TIRES AND RAILROAD TIES, GROWING AT A RATE OF APPROXIMATELY 240 MILLION TIRES/YEAR AND 14 MILLION RAILROAD TIES/YEAR. THESE WASTE FUELS EXPRESENT A SIZABLE RESOURCE. CURRENTLY OVER 80% ARE LANDFILLED, CONSTITUTING LOSS OF A SIGNIFICANT RESOURCE AND CREATING A MAJOR ENVIRONMENTAL PROBLEM. THE OBJECTIVES OF THIS PROJECT ARE TO IDENTIFY BARRIERS TO THE SUCCESSFUL BLENDING OF COAL WITH WASTE TIRES AND RAILROAD TIES IN STOKER-FIRED BOILERS, AND IDENTIFY PROCESS PARAMETERS THAT WILL ENABLE COAL/TIRE-DERIVED FUEL (TDF) AND COAL/RAILROAD-TIE-DERIVED FUEL (RTDF) COMBINATIONS TO PRODUCE TOTAL EMISSIONS WITHIN ENVIRONMENTAL REGULATIONS. IN PHASE I, SERIES OF EXPERIMENTS WILL BE CARRIED OUT IN A PILOT-SCALE STOKER TO ESTABLISH MAXIMUM WASTE TIRE AND RAILROAD TIE REPLACEMENT RATE AS A FUNCTION OF CHIP SIZE; OPTIMUM FEED LOCATION, OVERFIRE/UNDERFIRE AIR RATIO; OPTIMUM GAS/TDF CO-FIRING RATIO (IF NECESSARY); EFFECT OF TDFAND RTDF ON CRITERIA FOR POLLUTANT EMISSIONS, TRACE HYDROCARBONS, PARTICULATE MATTER, AND METALS; AND IMPACT OF TIRE BELTS ON GRATE DUE TO INTERACTION WITH COAL ASH. THIS PROJECT WILL DEFINE THE POTENTIAL FOR COAL/TDF AND COAL/RTDF CO-FIRING BASED ON TECHNICAL PERFORMANCE AND ECONOMIC CONSIDERATIONS ANDWILL ESTABLISH PROCESS DESIGN PARAMETERS THAT WILL BE USED IN THE DESIGN OF AN OPTIMM COAL/TDF OR COAL/RTDF STOKER SYSTEM. IN ADDITION, THE PROJECT WILL DOCUMENT ADVANTAGES TO THE INDUSTRIAL CUSTOMER THAT RESULT FROM COFIRING.