Tire Development for Effective Transportation and Utilization of Used Tires, CRADA 01-N044, Final Report

Abstract

Scrap tires represent a significant disposal and recycling challenge for the United States. Over 280 million tires are generated on an annual basis, and several states have large stockpiles or abandoned tire piles that are slated for remediation. While most states have programs to address the accumulation and generation of scrap tires, most of these states struggle with creating and sustaining recycling or beneficial end use markets. One of the major issues with market development has been the costs associated with transporting and processing the tires into material for recycling or disposal. According to a report by the Rubber Manufactures Association tire-derived fuel (TDF) represents the largest market for scrap tires, and approximately 115 million tires were consumed in 2001 as TDF (U.S. Scrap Tire Markets, 2001, December 2002, www.rma.org/scraptires). This market is supported primarily by cement kilns, followed by various industries including companies that operate utility and industrial boilers. However the use of TDF has not increased and the amount of TDF used by boiler operators has declined. The work completed through this cooperative research and development agreement (CRADA) has shown the potential of a mobile tire shredding unit to economically produce TDF and to provide an alterative low cost fuel to suitable coal-fired power systems. This novel system addresses the economic barriers by processing the tires at the retailer, thereby eliminating the costs associated with hauling whole tires. The equipment incorporated into the design allow for small 1-inch chunks of TDF to be produced in a timely fashion. The TDF can then be co-fired with coal in suitable combustion systems, such as a fluidized bed. Proper use of TDF has been shown to boost efficiency and reduce emissions from power generation systems, which is beneficial to coal utilization in existing power plants. Since the original scope of work outlined in the CRADA could not be completed because of lack of progress by the CRADA members, the agreement was not extended beyond February 2004. The work completed included the detailed design of the mobile unit, a general economic analysis of the operating the system, and outreach activities.