| OCR Text |
Show o Roasting of ores by burning metal sulfides to recover metal as metal oxides and sulfur as sulfur oxides. o Converting metal oxides to volatile chlorides in a high-temperature environment sustained by coal burning. o Incinerating industrial solid and liquid waste into stable and sterile combustion products. o Burning high-sulfur caking coal in an environmentally acceptable manner. o Converting coal into gaseous fuel by partial oxidation in the presence of steam (coal gasification). Many of the coal FBC applications provide a basis for methods which, with modifications, will handle tire rubber. To illustrate this, comparative tire and coal analyses are shown in table 1. From a fuel standpoint, there is little significant difference between coal and tire rubber. Tire rubber is very similar to and could be treated as a low/moderate-sulfur eastern coal with a high volatile matter content. A conventional incinerator specially designed for tire burning offers limited fuel flexibility. It can burn only the limited number of fuels which have properties close to those of tires. It is environmentally acceptable, with reasonable combustion efficiency. The reliability of the tire incinerator is adequate. The primary drawback of the incinerator especially designed for tire burning is its lack of flexibility for burning a wide variety of fuels. On a short-term basis, it is feasible to blend shredded tire rubber with coal and/or hog fuel (wood waste from wood cutting) for boiler applications. This practice of blending fuels has been conducted in the past with no severe adverse effects reported, and may be expected to continue. As the energy crunch intensifies, there will be resulting economic pressures to utilize alternative fuels in existing solid fuel-fired boilers. These boilers may not be readily adaptable and the sulfur dioxide emission requirements may create problems for owners of boilers without sulfur dioxide emission control provisions. The chart shown in table 2 gives an idea of coal feed property requirements versus types of boilers. This chart shows that of all the boiler types, the fluidized-bed combustion boiler offers the most fuel flexibility. When considering contemporary tires as a supplemental boiler fuel, the steel beads and steel and glass belts pose a need for particular consideration. Conventional boilers are not able to easily accommodate significant quantities of trapped iron or steel objects (beads and belts). Fluidized-bed combustors have already demonstrated great flexibility and appear able to tolerate the necessary amounts of these materials. 11-11 |
