Note: Descriptions are shown in the official language in which they were submitted.
ii
CA 02087826 2003-09-03
APPARATUS FOR INJECTING TIRES INTO ROTARY KILNS
Background of the Invention
The present invention relates to devices for burning tires in rotary kilns
and, more particularly, to devices for injecting tires through the shell wall
of
rotary kilns.
The problem of disposal of scrap tires, typically from automotive use,
is a growing one. At present, approximately 240 million scrap tires are
generated
each year in the United States. The problem of tire disposal is compounded by
the
fact that many landfills are now refusing to accept whole scrap tires
Consequently, scrap tires must first be shredded or chipped in order to be
accepted by landfills, which is a costly process and requires expensive
chipping
machinery.
An alternative is to burn the scrap tires whole. A preferred
environment for burning scrap tires is a cement kiln, since temperatures
within the
kiln typically reach 2900°F - sufficient to break down the constituents
of the tires.
A preferred zone of a rotary cement kiln for burning whole tires is the
calcining
zone, where the temperatures range from between 1000° to 2000°F,
a preferred
temperature being at about 1500°F. Lower temperatures could result in
slower
ignition and burning, giving off airborne pollutants, and combustion at higher
temperatures may cause excessively rapid burning, which could create a
reducing
atmosphere in the raw feed and adversely effects the quality of the clinker
produced by the kiln. Tire burning methods, such as
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those disclosed in Z'suda U.S. Patent No. 4,256,503, which
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include depositing whole tires in the precalcining zone or
. the cooling,zone,, both,at the ends of the rotary kiln, are
less desirable for this reason.
However, attempts have been made to charge a
rotary kiln with whole tires directly through the shell wall
in the calcining zone. An example of such a device is shown
in Tutt, et al. U.S. Patent No. 5,078,594. That patent
discloses a device for charging whole tires into a cement
kiln which includes a radially extending drop tube which
projects inwardly from the shell wall, and an external
closure which includes spring-loaded gates that open, when
the device is at the twelve o'clock position, to allow a
tire retained within the closure to travel through the drop
chute onto the material within the cement kiln. A
disadvantage with this type of design is that the drop tube
rt~,ust be sufficiently long to project above the surface of
the raw feed mix when the drop tube is at the six o'clock
position, in order to prevent the raw feed from falling
downwardly through the drop tube at that position. This is
disruptive of the physico-chemical processes occurring at
this point in the cement kiln, and further, exposes the drop
tube to the exceedingly high temperatures in that zone.
Accordingly, there is a need for an apparatus for
injecting whole tires into a rotary kiln which has a low
profile within the kiln and yet prevents the material within
the kiln from falling outwardly through the feed tube.
Summary of the Invention
The present invention is an apparatus for
injecting one or more whole tires into a rotary kiln which
includes an inner shroud mounted within the shell and shaped
to provide a tangential entry path fox tires through the
shell and onto the material being treated within the kiln,
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and a gate,' single or multiple stages, mounted externally of
the shell and communicating with the shroud, for receiving
ti,res.and preventing escape of material and gases from the
shell, as well as limiting entrance of outside air into the
kiln through the apparatus. In a preferred embodiment, the
tangential entry design of the inner shroud is oriented with
the opening facing in a direction opposite the direction of
rotation, and the shroud profile is sufficiently low that
its profile does not project or barely projects above the
suzface of the material being treated within the kiln when
the apparatus is at oz near the six o'clock position. As a
result, the disturbance of kiln material by the shroud is
reduced, as compared to prior art drop tube designs.
The gate includes a housing projecting
substantially tangentially from the external surface of the
shell, and the housing includes a pair of doors or a single
dooz which opens automatically when the housing approaches
the twelve o'clock position, and close when the housing is
at the six o'clock position. Cams or toggles may be used to
effect the gate opening.
The apparatus of the invention also includes a
feeding mechanism which includes a feed table and a double-
acting cylinder motor which, when actuated, displaces a tire
on the table sidewardly into the tray housing. The tray
housing pzeferably includes a radially outwardly projecting
tray which becomes aligned with the table when the cement
kiln rotates. A switch senses the alignment of the tray and
table, and actuates the cylinder motor to displace a tire
from the table into the tray. An alternate embodiment
utilizes a table and tray fabricated from rods that allow
the two to intermesh so that the table will pickup the tires
from the tray.
The table receives tires from an accumulator
conveyor which, in turn, receives tires from an upwardly
3S inclined conveyor which may be loaded by hand or by a
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a
.;
forklift. Consequently, the apparatus is sufficiently
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automated that it is unnecessary for personnel to be present
at the housing to load tires during kiln operation.
Accordingly, it is an object of the present
invention to provide an apparatus for injecting one or more
whole tires into a rotary kiln in which the internal shroud
component is of a sufficiently low profile that it does not
project materially above the level of the material being
treated within the kiln, and yet, does not allow material
being treated to flow out of the kiln; an apparatus in which
the housing external to the kiln shell includes gate or
gates to limit the influx of outside air, or the escape of
gases and material from the kiln; an apparatus which is
sufficiently automated that personnel usually are not
required to operate the apparatus adjacent to the kiln
shell; and an apparatus which can be operated continuously
with the kiln, is capable of receiving whole tires, and is
easy to maintain.
Other objects and advantages will be apparent from
the following description, the accompanying drawings and the
appended claims.
Brief Description of the Drawing
Fig. 1 is a schematic side elevation of a rotary
cement kiln.incorporating the tire injection apparatus of
the present invention;
Fig. 2 is a top plan view of the kiln and
apparatus of Fig. 1, in which the kiln is partially shown;
Fig. 3 is a detail of the apparatus of Fig. 1
showing an end elevation in section of the kiln apparatus
taken at line 3-3 of Fig. 2;
Fig. 4 is the detail shown in Fig. 3, but rotated
so that the injecting apparatus is substantially vertical;
Fig. 5 shows the detail of Fig. 4 in which the
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apparatus has been rotated substantially to a six o'clock
w- _
position;
Fig. 6 is, a detail view .similar to Fig. 3 ,showing
an alternate embodiment of the tire injection apparatus of
the present invention;
Fig. 7 is a detail of Fig. 6 showing an end
elevational view of the apparatus taken along line 7-7 of
Fig. 6;
Fig. 8 is a detail of Fig. 6 showing an
elevational view of the gate of the apparatus taken along
line 8-8 of Fig. 6; arid
Fig. 9 shows the detail of Fig. 6 in which the
apparatus is rotated so that the gate is in an open
position.
Detailed Description
As shown in Figs. 1 and 2, the apparatus of the
present invention, generally designated 10, is used in
combination with a cement kiln 12 having a rotating shell 14
with an outer skin 16 of steel and an inner refractory
lining 18 (see also Fig. 2). Within the shell 14 is a bed
of material in process 20 (see also Fig. 3)
The apparatus 10 includes a tire feeding component
22 which consists of a shroud 24 and an outer housing 26.
The component 22 engages an opening 28 in the shell 14 (see
Fig. 3) at the calcining zone of the kiln 12, and includes a
support plate 30 which is attached to the skin 16 of the
shell 14 and a raised collar 32 which surrounds a central
opening 34 formed in the support plate.
The shroud 24 includes a radially oriented inner
wall 36, a tangentially oriented outer wall 38 and side
walls 40. The walls 36, 40 are lined with refractory 42 and
wall 38 is embedded in the shell refractory 18. The shroud
24 is shaped so that it does not project above or marginally
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projects a_bove.the surface of tl-ie material bed 20 when the
shroud is at approximately the sir, o'clock position relative
to shell 14 (see also Fig. 5).
The outer housing 26 includes brace 45,, tray 46
projecting tangentially outward and gates 48, 50. Gates 48,
50 are actuated by suitable counterweights or external earn
or toggles, which pivot the gates from the closed position
shown in Fig. 3 to the open position shown in Fig. 4. The
tray 46 includes an open top 55 for receiving one or. more
tires 58. As seen in Fig. 4, the orientation of the housing
26 and shroud wall 38 are such that a tire path is formed
which is substantially tangential to the surface of the kiln
lining 18. Specifically, the angle shown in Fig. 4 is a
nominal angle A of 50o with a radius line _B intersecting
wall 38. This tangential arrangement allows a shroud 24
design which is sufficiently low profile to pass beneath or
nearly beneath the surface of the bed 20 within the kiln
shell 14, thereby minimizing disturbance to the bed 20.
As shown in Figs. 1 and 2, the apparatus 10
includes a receiving table conveyor 56, an accumulator
conveyor 59, and inclined conveyor 60. A double-acting
cylinder feeder 62 is positioned adjacent to the receiving
table 56 and is actuated to displace tires 58 sidewardly
from the table into the tray 46. A switch 64 or other
timing device signals a controller 66 which actuates the
cylinder 62 when the tray 46 is in the position shown in
Fig. 3.
The operation of the apparatus 10 is as follows.
Tires 58 (Figs. 1 and 2) are loaded upon the inclined
conveyor 60 and conveyed upwardly to the accumulator
conveyor 59 where they collect until up to four tires are
stored upon the conveyor. With each succeeding tire, a tire
58 is displaced onto the receiving table 56. When the kiln
12 rotates the outer housing 26 to a three o'clock or
substantially horizontal position, the switch 64 actuates
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the cylinder 62 which displaces the tire 58 through the
opening 55 in the tray 46. During this operation, the gates
48, 50 are closed.
When the kiln 14 has rotated such that the housing
26 is inclined at approximately 10° above the horizontal, a
counterweight moves thereby opening the gates 48, 50. An
alternate actuation may be to use a cam or toggle to open
the gates. As the kiln continues to rotate to the position
shown in Fig. 4, one or more tires 58 slides along the outer
housing 26 and through the shroud 24 into the interior of
the kiln shell 14. When the housing 26 has rotated to an
orientation which is inclined approximately 10° past
vertical or twelve o'clock, the counterweight swings to
close the gates 48, 50. Alternately an external cam or
toggle may close the gates. As shown in Fig. 5, once the
last tire has entered the bed 20, burning of the tires will
commence. Because of the reverse entry angle of the shroud
24 relative to kiln 12 rotation, the material being treated
can only partly enter the shroud and thus is retained in the
kiln. The cycle begins anew for a subsequent tire 58 when
the outer housing 26 again reaches the position shown in
Fig. 3.
Accordingly, the entire process is automated from
the point at which tires are loaded on the inclined conveyor
60, and personnel are not required to be present at the
receiving table 56.
An alternate embodiment of the tire injection
apparatus 70 is shown in Fig. 6. The apparatus 70 includes
a tire feeding component 72 which consists of a shroud 74
and an outer housing 76. The component 72 engages an
opening 78 in the shell 14 at the calcining zone of the kiln
12, and includes a support plate 80 which is attached to the
skin 16 of the shell 14 and a raised collar 82 which
surrounds a central opening 84 formed in the support plate.
The shroud 74 includes a radially oriented inner
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wall 86, a tangentially oriented outer mall 88 and side
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walls 90. The walls 86 and 90 are lined with refractory 92
and wall 88 is embedded in the shell refractory 18.. The
shroud 74 is shaped so that it does not project above or
marginally projects above the surface of the material being
treated 20 when the shroud is at approximately the six
o'clock position relative to shell 14.
The outer housing 76 includes a brace 94
projecting radially outward from the inner wall 86 extending
and attaching to the support plate 80. The outer housing 76
also includes a tray 96 projecting axially away from the
shroud 74. As can be seen in Fig. 7, the tray 96 includes a
plurality of forks 98 positioned along the base fox picking
up tires 58. The table also includes a plurality of forks
98. The tray forks pass through or between the table forks
99 to pickup the tires from the table. The tray includes an
open top 100 ~pr receiving one or more tires.
Positioned between the tray and the brace 94 is a
gate 102. Gate 102 is pivotally attached to the housing 76
by a shaft 104 as also can be seen in Fig. 8. The gate 102
is balanced by counterweights 106, 108 located on either
side of the gate and actuated by an external camrail 110.
In addition to the counterweight for balance, springs can be
used to keep the gate closed. Counterweights 106, 108
extend downwardly from shaft 104 by supports 112 and 114.
The gate 102 includes a cam follower 116 which comprises a
wheel 118 positioned between arms 120, 122 on an axial 124.
Arms 120 and 122 extend from a collar 126 located on shaft
104. Camrail 110 is supported externally from the kiln by a
cam support structure 127. The cam 110 pivot the door 102
from the closed position shown in Fig. 6 to the fully open
position shown in Fig. 9. Specifically, the angle shown in
Fig. 9 is an angle C of approximately 30o with a radius line
D intersecting wall 88.
The apparatus 70 includes a receiving table
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conveyor 56, an accumulatar conveyor and .inclined conveyor
~,._ _
(not shown) similar to the previous embodiment.
Alternatively, a vertical delivery conveyor can be
substituted for the inclined conveyor. A double-acting
cylinder feeder 62 is positioned adjacent to the receiving
table 56 and is actuated to displace tires 58 sidewardly
onto the end of receiving table 56.
The operation of the apparatus 70 is as follows.
Tires 58 axe loaded upon the inclined conveyor and conveyed
upwardly to the accumulator conveyor where they collect
until up to four tires are stored upon the conveyor. With
each succeeding tire, a tire 58 is displaced onto the
receiving table 56. When the kiln 12 rotates the outer
housing 76 to a six o'clock or substantially vertical
position, the cylinder 62 activates to displace the tire 58
onto the end of receiving table 56. During this operation,
the gate 102 is closed.
When the kiln 12 has rotated such that the housing
76 is inclined to approximately 10~ below the horizontal,
the cam follower 116 engages the camrail 110 and begins to
open the gate 102. As the kiln continues to rotate to the
position shown in Fig. 9, one or more tires 58 slide along
the outer housing 76 and through the shroud 74 into the
interior of the kiln shell 14. When the housing 76 has
rotated to an orientation which is inclined approximately
loo past vertical or twelve o'clock, the cam follower 116
disengages from the camrail 110 and spring 128 close the
gate 102. Spring 128 is attached to gate 102 by flange 130
and to support plate 80 by flange 132. Similar with the
previous embodiment, because of the reverse entry angle of
the shroud 74 relative to kiln 12 rotation, raw feed can
only partially enter the shroud and thus is retained in the
kiln. The cycle begins anew for a subsequent tire 58 when
the outer housing 76 again reaches the position shown in
Fig. 6.
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Accordingly, the entire process is automated from
the point at which tires are loaded on the inclined conveyor
and personnel are not required to be present at the
receiving table 56.
While the preferred embodiment shown in the
drawings indicates a feed component 22 or 70 which injects
tires at an angle of approximately 500 or 300 counter-
clockwise from a radial line the feed component 22 or 70 can
be oriented at a larger angle which is greater than 500 or
300 counter-clockwise from a radial line, such as 600 or
400. Similarly, the feed component can be angled to provide
a tire trajectory path which is somewhat less, although this
tends to increase the profile of the shroud 24 within the
shell 14.
While the form of apparatus herein described
constitutes a preferred embodiment of the invention, it is
to be understood that the invention is not limited to this
precise form of apparatus, and that changes may be made
therein without departing from the scope of the invention.
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