Tire-Dereived Fuel (TDF) is currently the
largest single market for waste tire management. It has occupied approximately
82% of overall waste tire recycling.
Three major combustion facilities for TDF are cement kilns, power plants
and pulp/paper boilers. One hundred and seven of these combustion facilities
were conducting or planning test burns as a percentage or even full portion
of their fuel requirement in 19961).
In 1998, thirty states were supporting waste tire management by charging $1-3 per tire, and this kind of economic incentive makes TDF a feasible recycling option compared to other alternatives.
As an energy source, TDF has good potential compared to other fuel source
alternatives.
TDF has a high fuel value of approximately 12,000 to 16,000 BTU
per
pound, compared to coal (12,000 BTU per pound) and wood (5000 BTU per pound).
Theoretically, scrap tires could provide an energy source of 0.078 quadrillion
BTU (78,000,000,000,000 BTU) per year, since approximately 270 million
tires are discarded each year with each tire weighing an average of 20
pounds. This is equivalent to 13 million barrels of crude oil2).
The other important advantages of TDF are a compact and consistent
composition and a low moisture content.
These properties are important for combustion facilities.
A major technological consideration of TDF applications is related to
emission control from the combustion facilities.
The emission level of pollutants from an optimized TDF facility is
potentially lower than from other conventional facilities. Studies
have shown that the emission of metals (Zinc, Thallium, Cadmium, Lead,
Nickel and Chromium), CO, SOx, NOx, HCl, Dioxin and Fluoride are the same
as from other conventional facilities. One million tires used as
fuel in place of coal would reduce carbon dioxide emissions by 19.5%3).
Despite this fact, TDF facilities are subject to the not-in-my-back-yard (NIMBY) syndrome. In 1998, the number of TDF facilities decreased to 724). The reasons for this regress are assumed to be due to increasing environmental pressure and a decreasing economic advantage compared to other fuel alternatives.
This section will discuss the environmental and economic issues related to TDF applications.
Emission Control at the TDF
Facilities
Economic Consideration Relating
to TDF
Extensive information concerning TDF can be found from the following sources:
Related Sites:
Waste tires that are shredded into pieces approximately 1-2 inches in size are called Tire-Derived Fuel (TDF). TDF is classified into several grades. Tires contain about 30% of metal wire and fabric, and removal of the wire involves an expensive process, which requires fine shredding and the use of powerful magnets. Wire-free TDF is a considerably higher grade.
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| TDF |
83.87
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7.09
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2.17
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0.24
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1.23
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4.78
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0.62
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36,023
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15,500
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| Coal |
73.92
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4.85
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6.41
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1.76
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1.59
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6.23
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5.24
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31,017
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13,346
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British Thermal Unit is a unit of measurement of heat or energy, usually abbreviated as Btu or BTU. One Btu was originally defined as the quantity of heat required to raise the temperature of 1 lb (0.45 kg) of water from 59.5 F (15.3 C) to 60.5 F (15.8 C) at a constant pressure of 1 atmosphere. The Btu has been redefined as equal to 1055 joules or approximately 0.293 watt-hour.
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