Note: Descriptions are shown in the official language in which they were submitted.
In my United States Patent No. 3,845,941 dated November 5, 1974,
there are described processes and apparatus for recycling used asphalt-aggre-
gate compositions. The apparatus, of which the present invention constitutes
an improvement, includes an elongated cylindrical drum having a plurality of
heating tubes extending substantially along the length of the drum interior.
Used asphalt-aggregate compositions are introduced into an input end of the
drum as it is rotated while heating the tubes so that the composition becomes
heated gradually and mixed as it contacts the heated tube surfaces. The drum
is tilted so that the composition is drawn gravitationally from the input end
to the output end.
As described in my aforesaid United States Patent, a hopper and
chute type of apparatus is used to introduce the composition into the heating -
and mixing drum at the cool input end. The present invention is intended to
utilize a different means for introducing compositions into the cool input
drum end incorporating a self-loading feature whereby composition is intro-
duced into the drum as it is rotated.
In my United States patent No. 3,845,941, there have been described
ways of removing and venting water vapor from the used asphalt-aggregate
compositions which often have a significant amount of water or moisture there-
; 20 in. The presence of moisture in the material as it nears or approaches the
hotter apparatus end increases the energy requirements to heat the composi- ~-
tion to required output temperatures of 250-300 F or so. This problem is
compounded in the apparatus as the moisture boils off only to condense in the
cooler drum end. Unless the water vapor is properly vented or exhausted
during the heating process, the repeated condensation will affect the effi-
ciency of the process. Accordingly, in another embodiment of this invention
- one or more ports intermediate the cool input and hot output ends of the
mixing drum are provided for venting water vapor at or near the location at
which the composition is heated to the water boiling point or temperature at
which moisture within the composition is vaporized.
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In my United States patent there is shown and described a chute
member on the forward output end of the apparatus from which heated and mixed
composition is drawn and recovered. In a preferred embodiment of the present
invention there is provided an improved means for recovering the composition
at the forward end of the apparatus.
The apparatus of the invention for mixing asphalt-aggregate
composition comprises an elongated rotating cylindrical drum having an
interior mixing chalnber and a plurality of scoops extending around the drum
exterior at one end which scoops each have a lip defining a scoop opening
for receiving composition, a plurality of input ports along the drum ex-
terior each communicating with the drum mixing chamber and one of said scoops
for directing composition into said chamber, and a stationary trough member
adjacent said drum end extending around at least a portion of said drum
exterior and having a trough cavity for receiving said composition and having
a sectional shape substantially like the periphery of said scoop lips and
slightly enlarged therefrom for successively receiving said scoops as said
drum is rotated.
In a preferred embodiment, each scoop picks up composition which
is then introduced gravitationally into the drum interior.
In a preferred embodiment, at least one port extends through the
drum at or near the location at which composition in the drum is heated to
or near the temperature at which moisture is vaporized and is vented directly
through the port into the atmosphere. Preferably, the scoops are secured
near or adjacent the water vapor exhaust port on the drum exterior. The
scoops cooperate with the trough member adjacent thereto and exteriorly of
the drum for picking up composition which falls through the exhaust port
during drum rotation.
In one preferred embodiment, a plurality of ports are spaced
around the drum exterior, communicating with the drum interior at or near the
hot forward output end of the apparatus and through which ports heated and
mixed composition is recovered as it falls gravitationally through the ports
during drum rotation.
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In the drawings,
Figure 1 is an end elevational view, partly cut away and in
section showing a scoop feed embodiment of the invention; ~:
Figure 2 is a perspective view showing the apparatus of Figure l;
Figure 3 is a perspective view of the forward end of the drum
apparatus of the invention showing product removal
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ports;
Figure 4 is an end elevational view of the apparatus of Figure
1 showing means for recovering composition from the apparatus; and
Figure 5 is a side view showing the embodiments of Figures
1-4 and moisture exhaust ports.
DETAILED DESCRIPTION OF THE INVENTION
SCOOP FEED APPARATUS
Referring to Figures 1 and 2 there is shown the scoop feed
embodiment for a cylindrical heating and mixing drum 12, preferably of the
type disclosed in my aforesaid co-pending applications and patent. It will
- 10 be noted by observing Figure 5 that this scoop feed embodiment is provided
at or adjacent the inlet or cold end of the apparatus into which composition
is initially introduced and which composition is drawn gravitationally as
it is gradually heated and mixed toward the opposite hot output end of the
drum. As shown, six scoops four of which are designated 14, 16, 18 and 20
are spaced around the exterior of the drum 12 adjacent end plate 21. Each
of the scoops protrude substantially from the exterior drum surface and are
provided with openings 19 and an internal cavity 13. Interiorly of the
scoops, a port 15 opens into the drum interior thereby providing an opening
between the scoop cavity and the interior chamber of the drum. The lip or
edge of the scoop provides a surface for engaging composition as the drum
rotates and as will be more fully explained hereinafter.
In combination with the scoop is used a receptacle or other
means for receiving composition and which receptacle is positioned adjacent
the drum whereby the scoops will pass through the receptacle interior during
drum rotation. A preferred type of such a receptacle comprises a trough 24
r preferably having sides 27 and a bottom 25 forming a cavity into which the
composition is fed. The size and shape of the trough should be such as to
allow the scoops to pass therethrough and scoop or pick up composition which
has been introduced into the trough cavity. The trough sides will preferably
have edges which follow the general shape of the drum exterior around which
they extend but which side edges are spaced at least slightly from the drum
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surface and avoid contact there~ith since the drum rotates while the trough
is maintained in a stationary position.
Means for introducing composition 31 into the trough is not
especially critical and any convenient means may be used. For example, in
Figure 1, there is shown a hopper and chute member 22 which communicates
with trough 24 and into which hopper composition is introduced utilizing a
conveyor system 20. The composition 31 falls from the conveyor, through
the chute and hopper gravitationally into trough 24. As drum 12 is rotated
counterclockwise, observing Figures 1 and 2, the scoops will successively
pass along the interior of trough 24 and composition will be forced into
the scoop as lip 23 of each scoop engages the material. The size of the
scoop opening is preferably sufficient to accommodate substantial mounts of
composition as the scoop continues to pass through the trough. Thus, the
edges of the scoop may form an opening only slightly smaller than the trough
interior. For example, observing Figure 1, scoop 18 shown in phantom is
in a position whereby composition is forced gravitationally into the scoop
as it continues to rise. Scoop 20 is in a position in which composition will
have substantially emptied through port 15 into the drum interior.
The size and shape of both of the scoops and trough is not
particularly critical. For example, the shape of the lips or edge of the
scoops may be rounded or straight and preferably being the same as that of
the interior trough cavity 29 but the latter being at least slightly
enlarged so as to achieve maximum efficiency in introducing composition
to the drum interior. The scoop walls are also preferably sloped as shown
in order to provide a chute or passageway for directing composition to the
port. For that purpose any convenient shape may be used. The number of
scoops and ports which they cover may also be varied depending on the size
of the drum and the amount of material which is to be continually or inter-
mittently introduced into the drum for heating and mixing. It is also
preferred that the scoops and ports are located on the drum adjacent end
wall 21 rather than substantially forwardly thereof in order to utilize the
maximum length of the drum in the heating and mixing process.
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C0MPOSITION
In Figures 3 and 4 there is shown another embodiment of the in-
vention in which a plurality of ports 33 are spaced around the exterior
surface of the drum 12 adjacent the forward drum end opposite the input
end previously described. These ports communicate with the drum interior
so that composition which has been heated and mixed in the drum as it is
drawn toward the forward drum end will pass through the ports gravitation-
ally. The size and spacing of the ports is not particularly critical so
long as product recovery is suitably achieved. Preferably the ports are
located next to, near or adjacent the forward drum end so as to avoid a
substantial space between the ports and the forward drum end wall in which
space heated material would be held and could not be readily recovered with-
out reversing the tilt of the drum or scooping it out by hand through the
ports. In the preferred embodiment shown, each of the ports is provided
with a cover 34 which is secured to a hinge 32 on which the covers pivot.
These hinges are designed so that the covers can swing or pivot freely t
about the hinge axis. In this manner, as illustrated in Figures 3-4, as
the drum rotates and the ports pass through the horizontal plane extending
across the diameter of the drum at approximately its center the covers will
begin to open gravitationally. As the drum continues its rotation, the
covers in the lower arc or segment of the drum are substantially opened so
as to allow product to fall through the ports.
This embodiment is preferably utilized in combination with a `
trough member 36 having a cavity therein for receiving the product composi-
tion as it falls through the ports. Figure 4 also illustrates a chute 42
adjacent the trough and under which extends a conveyor belt 40 for recovery
of the composition. The specific size of the trough is not particularly
critical but it is preferably designed with sloping sides so that the pro-
duct will readily be directed gravitationally for removal. As is also
shown, the upper sides will also terminate adjacent the drum exterior wall
and are spaced there~rom so as not to interfere with the drum rotation since
the trough is held in a stationary position. Moreover, any means for remov-
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ing the composition which has been received in the trough, such as the use
of the chute 42 and conveyor apparatus 40. Similar and equivalent means for
removing the composition will be understood by those skilled in the art.
The use of the hinged covers also provides for closing of the
ports gravitationally as the drum rotates. As is illustrated in Figure 4,
the covers located in the upper arc or segment of the drum are in a closed
position. This offers the advantage in that hydrocarbon gases, smoke and
the like given off from the heated asphalt near the hot forward end will
not be vented into the atmosphere through the closed ports. Of course, the
covers may not be fully closed until they are at least somewhat above the
center horizontal plane.
Figure 5 illustrates the use of an optional gas and vapor
accumulator collar 52 that may be used where prevention of venting hydro-
carbons into the atmosphere is important. The collar is hollow and extends
around the upper drum exterior thereby covering the ports. One or both ends
may meet the ends of trough 36 but a space between these ends along the side
where product is first recovered through the ports is preferred for obser-
vation of the recovery process as illustrated. Moreover, a conduit or pipe
54 also communicates between the collar and the furnace 46 in which a burner
52 directs heat into the heating tubes. In this manner, the furnace heating
chamber will cause a draft through the pipe to assist in pulling any gases
from the ~ollar to the furnace chamber. Moreover, since it will be under-
stood that composition passing through open ports in the lower portion of the
drum will occlude the openings and further prevent significant venting of
the vapors.
WATER VAPOR EX~AUST PORTS
Referring further to Figure 5, there are shown a plurality of
exhaust ports 58 which extend around the drum exterior and which ports com-
municate with the drum interior. These ports are spaced around the drum at
a location or position of the drum length at which the composition is heated
near the point at which the water vapor begins to vaporize in substantial
amounts. Preferably, each of the ports is provided with a cover in the form
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of a scoop 57 of a design substantially like that referred to in the scoop
feed embodiment previously described. Another stationary trough 56 extend-
ing around the lower drum segment or half, again, similar to the trough
previously described in Figure 2, is also used. The purpose for the trough
and the scoop shaped covers is to collect and pick up any composition that
passes through the exhaust ports gravitationally as the drum is rotated.
For example, as the ports pass through the lower arc during drum rotation,
some composition will fall through the ports, out of the scoops and into
the trough and will then be scooped up from the trough by the scoop shaped
covers as they pass through the trough cavity in a manner substantially as
described previously regarding the scoop feed embodiment.
The proper positioning of the water vapor exhaust ports is
important so that optimum or near optimum advantage of venting of the water
vapor is achieved. Again, positioning of the ports will be readily deter-
mined by selecting the position along the length of the drum mixer and
heater at which extensive moisture vaporization is realized. The asphalt-
aggregate is heated from ambient temperature at the cool input end to at
least about 225F and preferably above about 300F at the hot output end.
Thus, usually, composition temperature of about 210-215F is achieved some-
where between about one-half and about two-thirds of the length of the drum
from the cool end. Figure 5 shows the ports in such a position. As pre-
viously noted, this exhausting or venting of water vapor will obviate the
problem of repeated vaporization and condensation within the drum heating -~
and mixing chamber and the concomitant disadvantages of poor heating effi-
ciency and energy requirements. These as well as other advantages of the
apparatus and methods described herein will be evident to those skilled in
the art as will variations and modifications within the purview of the
invention.
