Note: Descriptions are shown in the official language in which they were submitted.
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I; Backaround and Field of the Invention
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This invention rela-tes to apparatuses for blending
particulate solids and further to gravity flow type of blenders
wherein the granular or particulate solids are withdrawn
simultaneously from a multiplicity of levels within a hetero-
geneous mass of the solids at various locations about the
mass and therafter recombined. It more particularly relates
to so-called single-pass type blenders.
Yrior apparatuses for blending dry particulate solids
are comprised of mechanical devices or gravity flow type
bulk silos. The mechanical devices utilized rotating agitators,
rotating shells, and mechanical or pneumatic conveyers to
blend the powdered solids. These devices have the disadvantages
though of small capacities, high horse power requirements,
and the fact that they are expensive to construct. The
gravity flow devices are limited, however, to free-flowing
granular materials and comprise basically a large container
for holding a bulk quantity of material, with a plurality
of tubes having inlets located around the container. The
particles are drawn and flow under the force of gravity
to a common blending chamber. The granular solids can either
be withdrawn from the unit or re-circulated to the top of
the large container.
In the prior art, gravity blenders have a disadvantage
of a start-up heel occurring when the blender is filled.
The first material charged into the unit goes directly to
the blending chamber and is unblended. The normal procedure
in the past to correct this problem has been to discard
this start-up heel of material or to re-circulate all of
the material to -the top of the unit for additional blending.
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Blenders of the prior art are limited to materials
that are free-flowing when acting under the influence of
! gravity. The inlet to the blending tubes extends into the
! blending bin typically. This presents a restriction to
Il the flow of material. Further, the blending flow control
jl devices of past gravity blenders were designed such that
unless the material was free-flowing, it would tend to bridge
in the blending charnber. Thus, past gravity blenders were
~ unable to efficiently handle materlals having sluggish flow
¦¦ characteristics.
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SUMMARY OF IN~ENTION
In accordance with the invention there is provided an
apparatus for blending particulate ma-terials. Material holding
means defines an upper chamber for holding a supply oE
particul.ate material, the material holding means having at least
one wall, the~ wall of the material holding means having at least
two outlet ports spaced vertically and about a perimeter of -the
material holding means for receiving therethrough particulate
material from the upper chamber by gravity flow. Material.
blending means defines a l.ower chamber for blending particulate
materials, the material blending means having at least one wall,
the wall of the blending means having at least two inlet ports.
Conduits are disposed externally of the material holding means
and the material blending means, each intercommunicating one of
the outlet ports and one of the inlet ports for conveying a
stream of particulate material from the upper chamber to the
lower chamber by gravity flow. Valve means is disposed in the
material blending means, movable between closing and opening
positions relative to the inlet ports. Operating means operates
the valve means.
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~ The Drawings
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' Figure 1 is a side-eleva-tional view of a blender illustrat-
! ing the present invention.
'` Figure 2 is an enlarged cross-sectional view taken
. along line 2 of Figure 1.
Figure 3 is an enlarged, fragmentary cross-sectional
view taken along line 3-3 of Figure 1.
Figure 4 is an enlarged, fragmentary cross-sectional
view taken along line 4-4 of Figure 3 illustrating a second
embodiment of the present invention.
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Detailed Description of the Invention
Referring to Figure 1, an embodiment of the present
invention is illustrated generally at 10. Apparatus 10
includes a blending bin 12, which may be formed into a cylindri-'
cal housing from stainless steel, aluminum, steel or the
like. It is also within the scope of the present invention
to utilize an existiny storage silo or hopper and modify
it according to the present invention. Blending bin 12
has a material receiving port 14 at its upper end which
can communicate with a pneumatic conveyer (not shown) or
, the like to permit the entry of a mass of heterogeneous
material or materials into the blending bin . It is also
1~ within the scope of the present invention to provide a cap
Il (not shown) which can selectively open or close material
i! receiving port 14. The blending bin 12 is supported on
¦l its support surface S by a plurality of support legs 16
formed, for example, of elongated steel channels with pads
¦l attached to the upper end which are welded or bolted to
the upper cylindrical wall portion 20 of blending bin 12
and with a floor mounting plate 22 attached to the lower
end thereof to contact support surface S and provide support
for apparatus 10.
, A downwardly-converging conical portion 24 is attached
to and depends from upper cylindrical wall portion 20 of
the blending bin. The material in the storage bin will
flow from conical portion 2~ through diffuser cone 25 to
a lower blending chamber 26 which is attached to and depends
from lower conical portion 24. The blending chamber 26
at its lower end has an opening 28 which can be opened and
closed and when opened communicates with a pneumatic conveying
passageway (not shown) or similar collection assembly.
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A plurality of external blending tubes 30 are provided,
each being connected through an opening 32 flush with the
interior surface of exterior wall 34 of the blending bin
through a tube connecting mechanism, which is best shown
at 36 in Figure 2. Referring thereto it is seen that connecting ,
mechanism 36 comprises a short downwardly sloping connecting
-tube 38 being connected at its upper end to exterior wall
34 and at its lower end to a generally vertical blending
tube inlet manifold or connection 40. The blending tube
inlet manifold 40 is then connected to blending tube 30
by a suitable compression coupling means 42. The flush
openings 32 in wall 34 allow blending tubes 30 to utilize
the forces of the arch of the solids material in blending
bin 12 to push the materials into the blending tubes. It
is -thus not necessary to have the inlet projections in the
blending container as previously were needed. An alternative
embodiment (not shown) positions the blending tubes on the
inside sidewalls of the blending bin.
The lower ends of external blending tubes 30 communicate
directly with the openings 44 in diffuser cone 25. Although
only four blending tubes 30 are shown in Figure 1, it is
anticipated that about twenty spaced external blending tubes
would be utilized. Also, as best shown in Figure l, it
is desirable for each of the blending tubes 30 to communicate
with the interior of the blending chamber through openings
32 which are positioned at locations about the blending
bin spaced both vertically and horizontally. These tubes,
though pictured in the drawings as being circular, can also
have a cross-sectional configuration which is square, rectan-
gular or any similar shape. Additionally, it is also within
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the scope of the presen-t invention to provide for couplings
46 for connecting the portions of tubes 30 adjacent the
cylindrical wall portion 20 and the conical portion 24 so
that the tubes can closely follow the exterior contour of
the bin. Also, the blending tubes can be equipped with
suitable sight glasses (not shown).
The design of the blending tubes 30 of the apparatus
10 of Figure 1 provides for only a single communication
opening 32 directly to the interior of the blending chamber.
The alternative embodiment of Figure 4 provides for a multipli-
ci-ty of openings 32, 48, 44 with suitable connection members
36, 50, 51, respectively, passing through both the cylindrical
wall 20 and -the conical wall 24 of the bin chamber. This
provides for material to flow from more than one horizontal
plane of the bin into the same blending tube. This modified
embodiment of Figure 4 handles well the space restrictions
of smaller units.
As best shown in Figure 4, diffuser cone 25 comprises
a chamber lower conical surface 52 having a plurality of
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openings 54 therethrough. As illustrated in Figure 3, it
is anticipated that twenty openings through diffuser cone
25 evenly spaced will be provided communicating the lower
interior of the conical portion 24 with blending chamber
26 and twenty exterior openings 44 provided so that each
of the twenty blending tubes 30 can communicate with blending
chamber 26. A conical vibrating flow control valve 56 is
positioned beneath the cone surface 52 and is configured
to mate against the surface when in its uppermost position
thereby blocking all of the external and internal openings.
An actuator 58 positioned beneath the flow control valve
56 moves the valve between its uppermost position closing
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the openings and its lower position spaced from surface
52 allowing the ma-terial to pass through the openings 44,
54 and flow directly into the blending chamber 54. Actuator
58 can be pneumatically, electrically, or hydraulically
actuated, and either stationary or vibrating. It will be
appreciated that when the valve is moved to its lower position
all of the openings, both the external and internal, will
open at the same time. The present invention also provides
that actuator 58 can be adapted to vibrate the flow control
valve during the blending cycle. This allows the present
invention to handle materials having sluggish flow character-
istics which previously could not be effectively blended
in a single-pass blending apparatus.
As can be appreciated, the optimum blending is achieved
in gravity blenders such as the present one when the blender
has the most areas or inlets to the blending tubes. The
present invention utilizes the most efficient placement
of the blending tube inlets and still allows a compact arrange-
ment in the blending chamber. Single pass blending is achieved
by sealing off all of the outlets of the blending bin openings
at the time the blender apparatus is filled. At the start
of the blending cycle, the valve is open and the material
from all areas of the silo are combined simultaneously.
It is thus not necessary to discard or recirculate the "startup
heel" of material.
From the foregoing detailed description, it will be
evident that there are a number of changes, adaptations
and modifications of the present invention which come within
the province of those skilled in the art. ~owever, it is
intended -that all such variations, not departing from the
spirit of the invention, be considered as within the scope
thereof as limited solely by the appended claims.
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