Note: Descriptions are shown in the official language in which they were submitted.
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NETHOD AND APPARATUS FOR BLENDING SOLIDS OR THE LIKE
This invention relates to blending. In another aspect, the
invention relates to a novel apparatus and method for blending of particulate
materials.
It is often necessary to blend or homogenlze truck-size, hopper
car-size, or larger batches or quantities of particulate materials or solids
in order to produce uniform mixtures. In the plastics industry, for example,
slight variations in properties of polymers may occur in differen-t production
runs. Blending of the pellets made in such runs is important to insure
products of uniform quality. Efficient blending of particulate materials can
be accomplished by the use of apparatus which comprises a vessel having a
plurality of vertically extending tubes therein. The solids to be blended are
positioned within the vessel surrounding the tubes. The tubes are provided
with openings through which the particles enter the -tubes to flow by gravity
downwardly through the tubes to a common collection zone.
While a blending apparatus of the general type disclosed above has
been found to be quite ef~ective, it has been found to be desirable to obtain
an improved apparatus for sampling and blending of particulate materials or
solids that can more easily be fabricated in the field.
In accordanc~ with the present invention, an improved blender
apparatus of the general type described above is provided. A preferred
embodiment of the blenler apparatus of the present invention employs a blender
vessel having an outer storage chamber and a single inner mixing tube whereln
the inner mixing tube comprises a tube extending generally parallel to the
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vertical axis of the vessel and wherein the tube is divided into a plurality
of separate compartments by an inner divider means and wherein the -tube is
provided with a plurali-ty of openings so that each compartment is in direct
fluid flow communication with the outer s-torage chamber by way of at least one
of the openings.
It is an object of the present invention to provide improved blendsr
! apparatus for blending par-ticulate materials or solids.
It is another object of the invention -to provide an improved method
of blending particulate materials or solids.
It is another object of the invention to provide an improved blender
apparatus tha-t can be easily and economically fabricated in the field.
It is yet another object of the present invention to provide an
improved blender apparatus that has no need for in-ternal supports in order to
prevent structural failure.
It is a further objoct of the present invention to provide an
improved blender apparatus that can be easily cleaned and inspected for
obstruction.
It is still another object of the present invention to provide an
improved method and apparatus for blending particulate materials or solids
which method and apparatus are reliable and economical in operation.
Other aspects, advantages, and objec-ts of the present invention will
become readily apparent to those skilled in the art upon further study of the
instant specification, claims and drawings in which:
Figure 1 is a side elevation view of one embodiment of the present
invention with portions thereof broken away to illus-trate the lower portion of
the blender in vertical cross-section;
: Figure 2 is a horizontal cross-section view taken along line 2-2 of
Figure l;
Figure 3 is an enlarged horizontal cross-section view taken along
line 3-3 of Figure l;
Figure 4 is an enlarged hor:izontal cross-section view taken along
line 4-4 of Figure 1.
Figure 5 is an enlarged partial horizontal cross-section view
illustrating one of the four baffles of Figure 4.
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Figure 6 is an enlarged hori~ontal cross-section view taken along
line 6-6 of Figure 1.
Figure 7 is an enlarged side elevation view of the lower port:ion of
the embodiment of Fig~tre 1 with the front half of the vessel removed in order
to clearly illustra-te the baffle arrangement.
Referring now to the drawings~ and to Figures 1 and 2 in particular,
there is illustrated therein an upright~ generally cylindrical vessel 10
comprising a generally cylindrical side-wall 12, a top closure 14, and a
downwardly converging, generally frustoconically shaped bo-ttom wall or closure
16. The length to diameter ratio of the cylindrical vessel 10 is generally in
the range from about 1.5:1 to about 3.5:1. The top closure 14 is provided
with a solids inlet or filling port 18 and a vent 20. The top closure 14 is
provided with a first opening 22, and the bottom wall or closure 16 is
provlded with a second opening 24. A single mixing tube 26 having a first end
28 and a second end 30 is positioned with -the first end 28 above the top
closure 14 and the mixing tube 26 passing through the first opening 22 which
opening 22 is suitably sealingly engaged with the outer surface of the mixing
tube 26. The mixing tube 26 extends downwardly through -the vessel 10 and
through -the second opening 24 in the bottom wall 16, which opening 24 is
suitably sealingly engaged with the outer surface of the mixing tube 26. The
second end 30 of the mixing tube 26 is positioned beneath -the bottom wall or
closure 16 of the vessel 10.
The interior of the mixing tube 26 is provided with a longitudinally
extsnding divider means for dividing the mixing tube into a plnrality of
longitudinally extending compartments. Preferably, the divider means divides
the mixing tube into from about 4 to about 36 longitudinally extending
compartments. Nore preferably, the divider means divides the mixing tube into
from about lO to about 30 longitudinally extending compartments. The mixing
tube 26 is provided with a plurality of openings so as to provide direct fluid
flow communication between the annular space between the interior of the
vessel 10 and -the exterior of the mixing tube 26 and the plurality of
longitudinally extending compar-tments of the mixing tube 26. The ratio of the
diameter of the cylindrical vessel 10 to the diameter of the mixing tube 26 is
generally in the range of from about 5:1 to about 15:1.
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A preferred embodi.ment of the mixing tube 26 is ill~lstrflted in
Figure 3. In the preferred embodiment, the mixing tube 26 comprises an ou-ter
tube 32 and an inner tube 34. The inner tube 34 is concentrically positioned
within the outer tube 32 to thereby Eorm an annular space -therebetween. A
plurality of longitudinally extending divider plates 36 are positioned within
the annular space between the inner tube 34 and the outer tube 32. Each
divider plate 36 has a first edge 38 that is positioned in direct contact with
the outer wall of the inner tube 34J and a second edge 40 that is positioned
in direct con-tact with -the inner wa~l of -the outer tube 32. Each divider
plate 36 extends at least substantially the full length of the inner tube 34,
thereby dividing the annulflr space between the inner tube 34 and -the outer
tube 32 into a plurality, preferably from about 4 to about 36, of
longitudinally extending compartments 42. Preferably, the longi-tud:Lnally
extending compartments 42 each have approximately the same cross-sectional
area.
The outer tube 32 of the mixing tube 26 is prov:ided with a plurality
of openings 44. The openings 44 are positioned a-t varying elevations on the
mixing tube 26 between the top closure 14 and -the bottom wall or closure 16 of
the vessel 10. The openings 44 are positioned around the circumference of the
mixing tube 26 so that each longitudinally extending compartment 42 is in
direct fluid flow communication with the annular space between the interior of
the vessel 10 and the ex-terior of the outer tube 32 by means of at least one
opening 44. The openings 44 can be of any suitable size and shape that will
allow the free flow of particulate materials or solids from the interior of
the vessel 10 into the longitudinally extending compartments 42. Preferably,
the openings 44 have a sufficiently narrow dimension in the horizontal
direction that each opening 44 provides direc-t fluid flow communication from
the interior of the vessel 10 to only one of the longitudinally extending
compartments 42. Preferably, the openings 44 are elongated so as to have a
greater length in the vertical direction than the length in the horizontal
direction so as to allow a maxlmum flow rate from the interior of the vessel
10 to the longitudinally extending compartmen-ts 42 without allowing flow from
the interior of the vessel 10 to more than one longitudinally ex-tending
compartment 42 through any one opening 44.
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In a preferred embodiment of the invention, for every opening 44
positioned at a part:icular eleva-tion there exi.sts a second opening 44 at
approximately the same elevation positioned at the opposite side of the outer
tube 32 as illustrated in Figure 3. The purpose of the second opening 44 is
to eliminate the pressure buildup against the outer tube 32 that is crea-ted bg
the flow of material toward the first opening 44. I-t is not necessary for
each opening 44 to have a diametrically opposed second opening 44 at
approximately the same elevation; however, by positioning a plurali-ty of
diametrically opposed openings 44 at various elevations along the outer tube
32, the external pressure upon the ou-ter tube 32 created by the flow of
material will be balanced, thereby eliminating the need for external tube
supports that may obstruct the flow of ma-terial inside the vessel 10.
At leas-t one bottom opening 45 in the outer -tube 32 is posi-tioned in
contact with the edge or line of intersection along which the mixing tube 26
contacts or intersects the inner surface of the bottom wall or closure 16 of
the vessel 10. Preferably, a plurality of bot-tom openings 45 in the outer
tube 32 are positioned in evenly circumferentially space relation around the
outer tube 32 in contact with -the edge or line of in-tersection along which themixing tube 26 contacts or intersects the inner surface of the bottom wall or
closure 16 of the vessel 10. In the preferred embodiment illustrated in
Figure 6, four bottom openings 45 are posi-tioned in evenly circumferentially
space relation around the outer tube 32 in contact with the edge or line of
intersection along which the mixing tube 26 contacts or intersects -the-inner
surface of the bottom wall or closure 16 of the vessel 10.
At least one baffle 46 is positioned in contact witll the bottom wall
or closure 16 of the vessel 10 so as to direct particulate materials or solids
toward the bottom openings 45 that exis-t in contact with the edge or line of
intersection that exists between the mixing tube 26 and the inner surface of
the bottom wall or closure 16 of the vessel 10.
The Figures 4 and 7 illustrate a vessel 10 which is provided with
four separate baffles 46 in contact with the bottom wall or closure 16 of the
vessel 10. The baffles 46 are equally circumferentially spaced around the
mixing tube 26 so as to direct Elow of particulate materials or solids to four
equally spaced locations along the edge or line of intersection along which
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the mixing tube 26 intersects the lnner sllrface of the bot-tom wall or closure
16 of the vessel 10.
As shown in ~igures 5 and 7, each baffle 46 comprises a first side
48 and a second side 50. The first side 48 and -the second side 50 have a
common first edge 52 so that the first side 48 and second 50 form an acute
angle. The first edge 52 has a firs-t end 54 i.n contact with the outer tube 32and a second end 56 in contact with the bottom wall or closure 16 of the
vessel 10. The first side 48 of the baffle 46 has a second edge 58 which
extsnds from the second end 56 of the first edge 52 along the bottom wall or
closure 16 of the vessel 10 to a point at the junction of -the bottom wall or
closure 16 and the outer tube 32. The first side 48 of the baffle 46 has a
third edge 60 tha-t extends from the first end 54 of the firs-t edge 52 along
the outer tube 32 to the point at which the second edge 58 in-tersec-ts the
junction of the outer tube 32 and the bottom wall or closure 16 of the vessel
10 .
The second side 50 of the baffle 46 has a second edge 62 which
extends from the second end 56 of the first edge 52 along the bottom wall or
: closure 16 of the vessel 10 to a point at the junction of the bottom wall or
closure 16 and the outer tube 32. The second side 50 of the baffle 46 has a
third edge 64 that extends from the first end 54 of the first edge 52 along
the outer tube 32 to the point at which the second edge 62 intersects the
~unction of the outer tube 32 and the bottom wall of closure 16 of the vessel
10 .
.: As illustrated in Figure 1, the vessel 10 can be filled with
particulate materials or solids to be blended by means of a conduit 70 which
communicates with the solids inlet 18. A condui-t 72, having control means
such as a rotary star valve 74 interposed therein, is connec-ted to the second
end 30 of the mixing tube 26 to withdraw blended particula-te materials or
solids. Conduit 72 is connected to a withdrawal conduit 76 in which a valve
78 is interposed. In some operations i-t may be desirable to recycle blended
partlculate materials or solids from the conduit 72 back to the upper region
of the vessel 10. This can be accomplished by means of a condult 80, having a
valve 82 interposed therein, which extends from condui-t 72 to the solids inlet
18. A conduit 84, having a valve 86 interposed therein, extends from a source
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of pneumatic pressure, not shown, to the inlet of conduit 80. The blended
particulate materials or solids can thus be elevated and reintroduced into the
vessel 10 via conduit 80 by means of pressur:Lzed air from the source of
pneumatic pressure. The vent 20 permits the transport air entering the
condui-t 80 to be exhausted from the vessel 10.
In a first method of operation in accordance with -this lnvention,
the rotation of valve 74 is stopped to block flow through the valve 74 and the
vessel 10 is filled with particulate ma-terials or solids to be blended via the
conduit 70. The valve 74 is then ro-tated to allow flow therethrough and -the
valve 78 is opened to permit the particulate materials or solids to drain by
gravity from the vessel 10 through the mixing tube 26 to the withdrawal
condult 76. Valve 86 is closed at this time so thflt no particulate ma-terials
or solids are recycled. In another method of operation of th:ls invention, -thevessel 10 can be operated in the same manner except -that blending is
accomplished continuously with particulate materials or solids to be blended
being introduced through the solids inlet 18 and wi-thdrawn through the conduit
72 at the same time. In s-till another msthod of operation, a part or all of
the blended particulate materials or solids can be recycled -through conduit 80
back to the solids inlet t8 for further blending.
It is presently preferred to assemble the vessel 10 illustra-ted in
Figure 1 in the following manner. Initially, -the mixing tube 26, as shown in
Figure 3, is for~ed. The outer tube 32, inner tube 34 and divider plates 36
are each formed separately by any sui-table means, such as extrusion. - The
first end 38 of each divider plate 36 is fixedly secured to the outer surface
of the inner tube 34 by any suitable means, such as welding, in order to form
an inner baffle means. Welding is defined for the purposes of this
application to mean the localized coalescencing of metal wherein coalescencing
is produced by heating to suitable temperaturesl with or without the
application of pressure, and with or without the use of filler metal.
Alternatively, the inner tube 34 and the divider plates 36 can be formed as
one single member by any suitable means, such as extrusion. The inner baffle
means formed by the combination of the inner tube 34 and the divider plates 36
is suspended over the outer tube 32 in axial alignment wi-th -the ou-ter -tube 32.
At least one of the inner baffle means and the outer tube 32 is moved in a
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direction toward the other. Preferably, the inner baffle means is lowered
into the outer tube 32 so that the inner surface of the ou-ter tube 32 is
sealingly engaged with the second end 40 of each divider plate 36.
plurality of openings 44 are cut into -the outer tube 32 by any suitable means
at varying elevatlons on the outer tube 32 posi-tioned around the circumference
of the outer tube 32 so -tha-t each longitudinally extending compartment 42 -that
exists between the inner baffle means and the outer tube 32 is in direct fluid
flow communication with the exterior of the outer tube 32 by means of at least
one opening 44.
The mixing tube 26 is thsn ax:ially aligned wi-th the vessel 10. The
first end 28 of the mi~ing tube 26 is then inserted through the second opening
. 24 in the bottom wall 16 of the vessel 10, then passed upwardly through the
entire length of the vessel 10. The outer surface of the mixing tube 26 is
fixedly secured to the inner surface of the bottom wall 16 of the vessel 10 by
any suitable means, such as welding.
The baffles 46 aro then fixedly secured between the mixing tube 26
and the bottom wall 16 of the vessel 10. The second edge 58 of the flrs-t side
. . .
48 and the second edge 62 of the second side 50 of each ba:Efle 46 are secured
to the bottom wall 16 of the vessel 10 by any suitable means, such as welding.
The third edge 60 of the first side 48 and the third edge 64 of the second
slde S0 of the baffles 46 are secured to the outer surface of the mixing tube
26 by any suitable means, such as welding. After the mixing tube 26 is
fixedly secured to the bottom wall 16 of the vessel 10 and the baffles 46 are
fixedly secured between the mixing tube 26 and the bo-ttom wall 16 of the
vessel 10, the top closure 14 is fixedly secured to the side wall 12 of the
vessel 10 with the mixing -tube 26 passing through the first opening 22 in the
top closure 14 so that the mixing *ube 26 is sealingly engaged with the top
closure 14, and assembly of the blending apparatus is complete.
It should be noted that a significant feature of the apparatus of
the present invention is that all particulate material flows through a single
mixing tube 26. With only a single mixing tube 26 -to be positioned within the
vessel 10, the apparatus is more easily fabrica-ted in -the field.
Additlonally, each longitudinally extending compartmen-t 42 of the mixlng tube
26 is essentially straight. Thus, the par-ticulate materials are neither
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subjected to angular flow within the longitudinally extending compartments 42
nor potential material reten-tion at angular welds, which provides greflter
assurance of equal flow from each longitudinally extending compartment 42.
Additionally, this provides for a simplified wash system of the apparatus by
providing for more complete cleaning of the longitudinally extending
compartments 42 and affording an improved inspec-tion potential of the
longitudinally extending compartments 42. Furthermore, the elimination of the
need for internal supports to hold -the mixing -tube 26 in position will
diminish the obstruction of flow patterns and possible retention of
particulate material within the vessel 10.
From the foregoing detailed clescription, it will be seen that the
: apparatus and method of i.ts use described and illustrated herein imminently
achieve -the objects of the present invention. Changes may be made in the
combination and arrangement of parts or elements as heretofore set for-th in
: the specification and shown in the drawings without departing from the spirit
and scope of the invention as defined in and limited only by the following
claims.
