Apparatus for pyrolyzing tires

Whole tires are heated in a pressure vessel to a range of between 700.degree. Farenheit and 900.degree. Farenheit, with pressure within the vessel achieved and maintained at 100-300 pounds per square inch. The vessel has a heat tube which extends through the center of the tires contained therein to uniformly apply heat. The method produces a low sulfur oil and gas, and a useable coke product from the pryolysis of the tires.

SUMMARY OF THE INVENTION 
This invention relates to the pyrolyzing of used tires to reduce the rubber 
to solid, liquid and gas components. 
BACKGROUND OF THE INVENTION 
Used tires are an environmental problem of large proportion. The extremely 
large quantity of tires discarded each year makes burial in landfills 
undesirable. Tires take up a tremendous amount of landfill space, are 
difficult to keep buried, and do not decay. 
Tires may be burned and used as a source of energy. However, the burning of 
tires creates additional environmental problems in the form of air 
pollution as a result of burning. 
Tires may be liquified. However, the energy required for the liquification 
process of a tire is cost prohibitive. The liquification process also 
results in a change of the structure of the rubber which makes the rubber 
undesirable for many uses. 
Various devices are found in the prior art for pyrolyzing tires. These 
devices use heat and relatively high pressures, or subatmospheric 
pressures. Some of the devices require the introduction of hydrogen into 
the pyrolisis process. Many of the devices require chopping of the tires, 
preheating of the tires or other preprocessing. 
SUMMARY OF THE PRESENT INVENTION 
The present invention provides a device into which whole tires may be 
inserted. Tires inherently have a round center void for mounting of the 
tire to wheel. The device of the present invention has a heating tube 
which is inserted through this center void as the tires are held within a 
vessel which allows the pressure within the vessel to be controlled. 
Heat is applied to the heating tube. The tires are pyrolized at a 
temperature of 700.degree. to 900.degree. F. As the temperature rises 
within the vessel, the pressure within the vessel begins to rise. The 
pressure is allowed to rise to a range of between 100 and 300 p.s.i., at 
which point gas is bled from the vessel, and collected. The placement of 
the heating tube through the center of the tires allows a uniform and 
efficient application of heat to pyrolize the tires without the 
requirement of chopping or reducing tires in size, yet allows the 
pryolisis to take place in a relatively short period of time. The 
pryolisis yields three components: a solid, coke like material; a liquid, 
which is similar to fuel oil; and a gas. The particular range of 
temperatures and pressures chosen yields a gas which is extremely low in 
sulfur, and an oil component which has a relatively low sulfur component. 
The coke contains levels of sulfur which are favorable when compared to 
coke produced from many grades of coal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing figures, the assembled vessel is shown in FIG. 
1. FIG. 2 demonstrates the larger components of the device. 
It preferred that the vessel 2 is cylindrical in shape, FIG. 2, having a 
round or circular cross section, FIG. 3. Tires 8 are assembled in a 
carriage 6. The grouping of the tires forms a somewhat cylindrical shape. 
Accordingly, the interior of the vessel is a cylindrical void in the 
preferred embodiment. While the overall shape of the vessel could be of 
other configurations, the interior void will be large enough to receive 
the carriage containing tires, and will preferably have a round or 
circular cross-section. 
A carriage 6 is provided in which tires 8 are placed. This carriage may be 
of any shape which will accept tires, and which is capable of insertion 
into the interior void of the vessel. However, the carriage may be a 
series of semi-circular members connected by longitudinal structures FIG. 
2. Means, such as casters, may be provided for guiding or transporting the 
carriage into the void, however, such means should be able to withstand 
the temperatures necessary operation of the device. 
Tires are placed on the carriage in a whole form, as they are typically 
discarded as used tires. It is not necessary to chop or otherwise reduce 
the used tires. It is preferable that the carriage hold multiple tires for 
optimal energy efficiency. 
The carriage containing whole tires is inserted into the interior void of 
the vessel. 
A heating tube 4 is present within the interior void of the vessel. The 
heating tube is longitudinally positioned within the vessel, from 
substantially one end of the vessel to the other end. As the tires are 
inserted by means of the carriage into the void, the center void of the 
tires allows the tires to surround the heating tube. Tires inherently have 
such a center void which allows tires to be mounted to a wheel. 
Accordingly, used tires will in all cases have present a void through 
which the heating tube will be present. 
The heating tube emits heat along its entire length. Any known means could 
be used for providing heat to the heating tube. Carbon fuels may be used. 
Carbon fuels will efficiently achieve the 700.degree. F. to 900.degree. F. 
which is necessary to pyrolize the tires. In fact, the gas byproduct from 
the pyrolysis may be burned and used to heat the heating tube. Heating 
means and blowers 12 may be provided to force the heat into the heating 
tube. 
An opening is provided on one end of the vessel through which the carriage 
is placed into the vessel and removed from the vessel. A door 10 is 
provided to cover the vessel and maintain the desired pressure within the 
vessel as the device is used. Any known means may be used for attaching, 
opening, closing and sealing the door. It is desired that the door be 
sealed as to allow pressure to be maintained within the vessel and to 
prevent the escape of gas in an undesired manner through the door. As 
shown, a series of nuts and bolts is used to attach the door, however, 
hydraulic or pneumatic closing means, or hinges, having seals which are 
adequate to seal the door, may be used. 
Means is provided to control the pressure within the vessel. A pressure 
gauge may be affixed to an opening 14 in the device to monitor pressure. 
An opening 16 may be provided to allow gas to escape from the vessel as it 
is heated to maintain the pressure within the vessel within the desired 
range. Means may be provided to collect gas as it is allowed to escape 
from the vessel. 
In use, the device is heated rapidly to an internal temperature of 
700.degree. F. to 900.degree. F. A temperature gauge may be inserted into 
the vessel through an opening 18 to determine temperature. Heat is 
provided to the heating tube by the desired means, whether by burning of 
fuel, or by electrical means, nuclear means, or other known means of 
providing heat energy, as long as the temperature within the vessel can be 
rapidly brought to 700.degree. F. to 900.degree. F. 
As the temperature within the vessel begins to rise, the pressure within 
the vessel will begin to rise. Once the pressure within the vessel 
achieves 100 to 300 p.s.i., pressure is regulated within the vessel by 
releasing gas. This gas is collected for subsequent use. 
The rubber component of the tires yield solid, liquid and gas components. 
Tires commonly have steel and other components as well. However, as the 
tires are pyrolized, rubber yields the usable solid, liquid and gas 
fractions. 
The solid, liquid and gas components which result may be used as fuels. 
Fuels containing high sulfur components are environmentally 
unsatisfactory. Since it has long been known to add sulfur to "vulcanize" 
the rubber for improved properties, the resulting fractions from the 
pyrolysis of tires as performed in the prior art may yield components 
having sulfur contents which are not satisfactory for use as fuels. 
However, the temperature and pressure ranges used in the present invention 
yield solid, liquid and gas components having satisfactory levels of 
sulfur when compared with similar materials from other sources. 
In use, tires are placed with the carriage. It is desired that multiple 
tires be placed with the carriage. The diameter of the cross-section of 
the vessel should be large enough to accept the tires and the carriage, 
but not significantly larger than the diameter of the largest tire to be 
placed within the vessel. Vessels or carriages could be designed as needed 
for various tire diameters. Tires are placed in the carriage; it is not 
necessary to chop or cut the tires prior to placement with the carriage. 
It is desirable to place multiple tires with the carriage for optimal 
energy efficiency. The vessel may be of any length, but should be long 
enough to accept numerous tires. There is no particular limit to the 
length of the vessel, other than efficiency in placing and removing tires 
from the vessel. The heating tube, which traverses the interior of the 
vessel in a longitudinal fashion, provided heat at all points within the 
vessel so that the vessel may be virtually any length. 
The tires are placed within the vessel with the center opening of the tires 
surrounding the heating tube. A door is placed over the opening of the 
vessel and fastened. Heat is supplied to the vessel through the heating 
tubes by the heating means. The internal temperature of the vessel is 
increased by the heating means and the heating tube to 700.degree. F. to 
900.degree. F., and maintained at that temperature. It is desirable to 
bring the internal temperature to the desired range as quickly as 
possible. As the temperature rises, the internal pressure of the vessel 
will rise. By means of a pressure relief valve 17, pressure is maintained 
at 100 to 300 p.s.i. The pressure is released by allowing gas to escape 
from the vessel. This gas is collected. The temperature should be 
maintained until the rubber of the tires is substantially reduced to a 
solid and a liquid. Heat to the device is then terminated, and the vessel 
is allowed to cool. 
The gas from the vessel has been collected into a suitable container for 
containing the gas. The liquid from the vessel, which is an oil, is 
removed from the container, as is the solid coke material. 
While the makeup of all rubber is not identical, the following analysis is 
typical for the gas taken from the vessel during pyrolysis: 
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COMPOUND MOL % 
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Nitrogen 21.218 
Oxygen 5.227 
Carbon Monoxide 3.788 
Carbon Dioxide 5.410 
Methane 48.888 
Ethane 6.617 
Ethylene 2.488 
Propane 1.678 
Propylene 0.580 
Isobutylene 1.793 
1,3-Butadiene 0.131 
N-Butane 0.133 
Trans-Butene-2 0.047 
Cis-Butene-2 0.101 
3-Methyl-Butene-1 0.030 
Isopentane 0.049 
Pentene-1 0.018 
2-Methyl-Butene-1 0.102 
N-Pentane 0.038 
Isoprene 0.052 
Trans-pentene-2 0.020 
Cis-Pentene-2 0.010 
2-Methyl-Butene-2 0.203 
Trans-1,3-Pentadiene 
0.006 
Cis-1,3-Pentadiene 0.024 
Cyclopentene 0.016 
Cyclopentane 0.005 
2-Methyl-1-Pentane 0.003 
3-Methyl-1-Pentane 0.003 
2-Methyl-pentene-1 0.003 
Hexene-1 0.003 
N-Hexane 0.008 
C6 Olefins 0.009 
3-Methylcylcopentene-1 
0.001 
Methylcylcopentane 0.002 
C7 Olefins 0.009 
Benzene 0.110 
N-Heptane 0.020 
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The total sulfur content is 9.0 parts per million. This gas may be used a 
fuel. The gas may be used a fuel to provide heat to the heating tube. The 
gas may be burned and used as a fuel in many applications. 
The liquid, or oil, has a typical analysis as follows: 
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Carbon 85.33% 
Hydrogen 
13.42% 
Nitrogen 
.21% 
Sulfur 1.04% 
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This liquid is suitable use a fuel oil. The oil yields 17,668 BTU's per 
pound. 
The solid, or coke, has a typical analysis with water removed as follows: 
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Carbon 83.89% 
Hydrogen 
1.34% 
Nitrogen 
0.75% 
Sulfur 2.47% 
Ash 11.28% 
Oxygen 0.32% 
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The coke may be used a fuel. Coke may be burned and used where solid coke 
fuels are used. 
The particular heat and temperature ranges used in conjunction with the 
method described above yield sold, liquid and as byproducts which may be 
used as fuels. These fuels have very desirable low sulfur qualities. The 
gas has an extremely low sulfur content of 9.0 parts per million, 
rendering the sulfur content of no significant consequence. The oil has a 
sulfur content of 1.04%, which compares very favorably with fuels which 
are currently available. When used a fuel oil, in many applications, it is 
not necessary to refine the oil produced by the process. Most of the 
sulfur from the rubber is deposited in the coke. Most coke is made from 
coal, and many grades of coal have relatively high sulfur levels. 
Resulting coke compares favorably with coke made from coal. If the coke 
levels are too high for the particular application, the coke could be 
processed to remove sulfur prior to burning. 
The process yields usable byproducts. The particular range of pressure and 
temperatures result in a depositing of the sulfur in the coke. It is more 
desirable to deposit the sulfur in the coke, rather than in the oil or the 
gas.