Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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HYDRAULIC ~EAN CLEANING
PROCESS AND APPARATUS
The invention relates generally to a process and
apparatus for hydraulically separating object of differing
specific gravities, and more particularly to hydraulic
removal of stones from beans and other legumes.
In the preparation of dried beans for use in
chili, tacos and other human foodstuffs, it is very
important to remove all stones to avoid dental injuries.
Stones commonly become mi~ed with beans during harvest. The
beans are customarily "field-cleaned" after harvest using
air separation and screening apparatus resembling that
disclosed in United States Patent No. 1,080,069 to Lyng.
However, air cleaning only removes light materials and
screening does not remove stones having sizes equal to or
smaller than the size o the beans. On the average, a
100 pound sack of beans includes about 200 stones aEter
screening. Conse~uently, further cleaning is reqtlired
to remove the remaining stones beEore the beans can be
prepared for consumption by humans.
It is known that vegetable matters and stones
have differing specific gravities. Accordingly, apparatus
for hydraulically separating or cleaning foodstuffs by
specific gravity have been proposed in United States
; patents to Cleveland, No. 2,422,657; Olney, No. 2,945,589;
Rakowsky, No. 2,879,889; Wallace, No. 3,792,772; and
Peterson et al, No.4,111l798. However, these devices do
not reliably separate stones from beans. Both beans and
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stones have a specific gravity yreater than water or
brine, and the specific gravity of the stones is greater
than, but often very close to that of beans. Existing
hydraulic separation methods and apparatus are too
inaccurate to separate objects of such close speciic
gravities with complete reliability.
Exposure to water during separation softens
the dried beans, making it necessary to cook them promptly
after separation. Conseuqently, separation must or-
dinarily be accomplished at the location where the beansare to be cooked. This presents no difficulty for large-
scale commercial food processors, but effectively pre-
cludes small-scale users, such as restaurants, from
using existing hydraulic separation devices. Existing
devices generally tend to be rather complicated, bulky
and expensive, rendering them unsuitable for small-
scale users. Consequently, such users must either buy
pre-cooked beans or separate stones from dried beans
manually. HoweYer, the proce~sed beans cost much more
than dried beans and manually separating stones from
beans is not only expensive because of the high labor
cost involved, but also unreliable because the percen-
tage of stones among the beans is small and the stones are
easily overlooked.
Thus, restaurants and other small-scale users
of dried beans and the like continue to need a compact,
inexpensive and highly reliable means for removing stones
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on the premises immediately prior to preparing the beans
for human consumption.
The concept of hydraulically separating objects
of different specific gravities has also been applied
more broadly, for example, in placer mining for gold.
One example of such apparatus is disclosed in United
States Patent No. 1,151,722 to Schiechel. Schiechel
teaches khe use of an upward current of water to buoy
lighter particles of sand upward to separate them from
the heavier metallic particles, and pulsating the cur-
rent to hydraulically agitate the particles to assist in
their separation. However, this apparatus is more com-
plicated than necessary, requiring pressurized sources
of both water and air. In addition t feed ~tock is added
at the top of the apparatus. This results in mixlng of
the feed stock into the upwardly flowing sand and water
so that some oE the heavier metallic particl~s are pre-
vented from sinking, and, thus, are not rel1ably epa-
rated.
One broad aspect of the invention is a method
of separating objects having slightly differing specific
gravities, comprising discharging a ~eed stock in a
continuous column downwardly from a first outlet into a
lower portion of a tank having a closed bottom and con-
taining a single liquid separating medium having a
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specific gravity less than that of the feed stock.
Additional separating medium is discharged ~rom a second
outlet into the tank at the level of said ~irs~ outlet
in a continuous downward flow closely surrounding and
parallel to the column of feed stock to entrain said
objects in the downward flow of said medium. This down-
ward flow is reversedl for example, by the bottom of the
tank, to esta~lish an upward flow of separating medium
around the column. ~The rate of discharge of separating
medium is controlled to produce a high velocity turbu-
lent downflow such that the feed stock is agitated and
drawn downwardly and laterally away from the first out-
let and objects of a lesser specific gravity are borne
upwardly by the medium while objects of greater specific
gravity sink ~o the bottom against the upward flow.
A further aspect oE tha method provides for
a~itating the feed stock entrained in the medium ~uE~i-
ciently to creat~ gaps between the ob~ects in a lower
portion of the tank so that object~ of greater speclfic
gravity can sink under the influence of gravity against
~he upward flow of said medium through said ~aps; accu-
mulating said entrained objects in an upper portion of
the tank to slow the upward movement and dampen the
agitation of ~aid objects so that any objects of greater
specific gravity borne upwardly by the medium lose the.ir
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momentum and begin to sink; and continuously overflowing
from said tank a portion oE th~ medium and objects
accumulated in the upper portion of the tank.
A second aspect of the invention is an appara-
tus suitable for carrying out the foregoing method.
Such an apparatus comprises a separator tank having a
- closed bottom, a feed stock conduit extending downwardly
into the tank and having a downwardly directed feed
stock discharge opening in a lower portion of the tank,
a liquid conduit having a downwardly directed liquid
discharge opening surrounding the feed stock discharge
opening and positioned at the same level as the feed
stock discharge opening, means for introducing a feed
stock of said objects into the feed stock conduit, means
for introducing liquid separatiny medium into the liquid
conduit, and means for controll.ing ~he rate at which
said medium is introduced into the liquid conduit to
produce a downElow of medium surrounding the feed stock
and having a high velocity, so that the Eeed stock and
liquid separating medium are simultaneously discharged
downwardly froln their respective openings into a lower
- portion of the tank to become mixed together and to
establish an upward flow of said medium around the co~-
duits which bears a lighter fraction of said feed stock
toward said spillway to overflow from the tank while a
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heavier fraction of said feed stock sinks against said
upward flow toward the bottom of the tank. The feed
stock discharge opening is spaced above the bottom wall
a distance greater than the dimensions of objects com-
posing the feed stock to be cleaned.
The downwardly expelled water entrains or
fluidizes the feed stock and carries it away from the
re~ion beneath the feed stock conduit. The bottom and
side walls of the tank deflect the water and entrained
fe~d stock laterally and then upwardly causing an upward
flow of water which counteracts the tendency of the
l;ghter weight feed stock elements to sink. The rate of
upward flow is adjusted so that the lighter elements are
borne upwardly while the slightly heavier elements are
allowed to sink.
The feed stock and liquid conduitæ are preEer-
ably cylindrical tubes concentr~cally positloned in the
tank and s,oaced apart such that liquid passagew~y has a
narrow radial width, for example, between about
one-eighth and one-quarter inches. The side wall of ~he
separator is likewise preferably cylindrically concen-
tric with the tubes and spaced laterally from the outer
tube a distance less than the outside diameter of said
outer tube. The discharge openings are preferably
spaced above the bottom wall of the tank a distance that
is less than the inside diameter of the inner tube but
suEficient to allow the feed stook to pass laterally
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be~ween the ends of t'ne tubes and the bottom wall of the
tank. The feed stock conduit can include a vibrator
~onnected for vibrating the feed stock and water con-
duits as a unit independently of the separator tank.
The feed stock conduit can be movably connected to the
hopper so that it can ~e vibrated relative to the bottom
opening of the hopper,
The bottom and side walls can be configured to
produce a roiling action or turbulence in the water as
its downward flow is r~versed. Such turbulence creates
spaces between the beans through which any stones can
sift downwardly toward the bottom of the tank. The
upwardly-borne feed stock thus accumulates free of the
heavier elements in an upper portion of the tank; there,
the lighter feed stock and water overflow a spillway
into a colander which strains the water into a sump~ A
pump recirculates the water back to the second conduit
mean~.
The tank can have vertical side walls and a
flat horizontal bottvm defining corners to create eddies
in the flow of water for catching and holding stones.
The tank and conduit means can be concentriGally cylin-
drical so that separation occurs uniformly around the
tank.
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The foregoing and other objects, features and
advantages of the invention will become more apparent
from the following description of a preferred embodiment
of the invention which proceeds with reference to the
drawings.
In the drawings,
Fig. 1 is a side elevational view of a hydrau-
lir bean cleaner according to the invention, portions
being cut away to show details of interior construction.
Fig. 2 is an enlarged side elevational view of
a portion of the apparatus of Fig. 1, substantial por-
tions being shown in vertical cro~s-section.
Fig. 3 is a cross-sectional view taken along
line 3-3 in Fig. 2.
Fig. 4 is a partlal cross-sectional view taken
along line 4-~ in Fig. 2.
Fig. 5 is a partial cross-sPctional view taken
along line 5-5 in Fig. 1.
Fig. 6 is a ~ide elevational view of ~he sepa-
rator tank and conduits oE Fig. 1 while in use, theseparator tank, but not the conduits, being shown in
cross section.
Detailed descripti _ of a preferred embodiment
Referring to Fig~ 1 a bean cleaner 10 according
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to the present invention has a hopper means 12, a sepa-
rator tank 14, a bean conduit 16 and a water conduit 18.
The separator tank has a spillway 20 for overflowing
water and beans into a colander 22 for straining the
water, but not the beans, into a sump 24. Pump means 26
connects the sump to the water conduit .18 for recirculating
the water. A vibra~or 28 is connected to the hopper 12
and another ~ibrator 30 is connected to the bean and water
conduits 16, 18. The foxegoing eleme~ts are all assem-
bled on a frame 32 supported on wheels or casters 34.
The hopper means 12 is positioned uppermoston the frame. Its principal elements are a.~olding hop~er
feed tray 36 and hopper 38. The feed tray is connected
abo~e the hopper by pivot 40 between two vertical frame
members 42, only one of which appears in the drawings.
The hopper is connected by four flexible mounts 44
between two parallel frame members 46 extending horizon-
tally from frame members 42. The hopper has a square
cross-section and its lower portion 48 de~ines an
inverte~ pyramidal funnel. At the end of the funnel is
a short cylindrical tube 50 defininy a bottom opening
of the hopper. Vibrator 28 is mounted on portion 48.
The water and bean conduits 16, 18 are mounted
on the horizontal leg 58 (Fig. 2~ of an L-shaped
bracket 52 and extend downwardly into tank means 14.
The bracket is connected by flexible mounts 54 to two
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horizontal cross frame members 56. Vibrator 30 is con-
nected to the vertical leg 59 of bracket 52 for vibrating
the bean and water conduits as a unit independently of
the separator tank.
Referring to Fig. 2, the horizontal leg 58 of
bracket 52 is flat and is sandwiched between flat mount-
ing plates 60, 62. The bean conduit includes an inner
cylindrical tube 64 extending vertically through bracket
leg 58 and mounting plates 60, 62, and connected to
upper plate 62. Tube 64 is aligned coaxially beneath
tube 50 and has an upper extension 65 flexibly connected
to the outlet of tube 50 by a flexible rubber or plastic
funnel 66. The flexible funnel enables vibrator 28 to
vibrate the hopper independently of the bean and water
conduits.
The water conduit includes an outer cylindri-
cal tube 68 concentrically surrounding tube 64 and spaced
therefrom to define an annular passageway 69. The radial
width of passageway 69 can vary depending on -the water
flow rate required, which in turn, depends on the di-
mensions of the separator tank, the specific gxavities
of the objects to be separated and the liquid separating
medium. Typically, this radial width is between about
1/8" and 1/4". The outer tube is connected to lower
plate 60. Plates 60, 62 form a water-tight fit about
bracket leg 58.
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A water connector 70 connects passageway 69
to a source of water. Referring to Fig. 3, connector 70
includes two collar portions 72, 74 clamped together just
below plate 60 by bolts 75 for a water-tight fit around
tube 68. A bore 76 extends horizontally through collar
portion 72 and tube 68 to connect passageway 69 with the
bore of a water pipe 78 connected to pump means 26. Pipe
78 includes a hand val~e 79 for adjusting the rate of
water flow into the separator tank 14.
The separator tank 14 has a cylindrical,
vertical side wall 80 and a flat, horizontal bottom wall
82 defining a closed tank bottom. The tank is preferably
made of transparent material such as clear plastic to
enable viewing the separation process and to monitor the
level of stones collected in the tank. The tank is
connected to frame members 42 by a U-shaped bracket 84
and is positioned so that side wall 80 concentrically
surrounds kubes 64, 68. The tank is removably mounted
on bracket 84 by two pairs o vertical mounting pins 86
received in holes 88 in two mounting plates 90 connected,
one spaced above the other, to side wall 80.
Tubes 64, 68 lead downwardly into the separator
tank. Their lower ends are spaced above bottom wall 82
a distance which is less than the inside diameter of
tube 64d but greater than the lengths of the beans to be
cleaned~ The lower ends of the tubes are cut off
substantially square and are open to provide a central
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bean discharge opening 92 and an annular water discharge
opening 94 surrounding opening 92. This configuration
enables introducing the bean feed stock into the tank as
close as possible to the tank bottom without the beans
backing up and jamming the bean conduit.
Spillway 20 is positioned in a rectangular
opening (not shown) through an upper portion of side wall
80. The spillway has vertical, parallel slde walls 96
and flat bottom wall 98 extending at a downward incline
from side wall 80 into colander 22.
Both the tank and tubes 64, 68 are vertically
elongated and laterally proportioned to provide an annular
vertical passageway between the outer tube 68 and tank
side wall 80. The passageway is relatively narrow so as
to constrict the water flow sufficiently to maintain
enough upward velocity to buoy the beans upward. In one
operable example, the vertical distance from bottom wall
82 to the bottom wall 98 of the spillway :Ls about
1-2/3 times the inside diameter of the tank, such diameter
being about 2-1/2 times the outside diameter of tube 68.
Thus/ the radial width of the annular passageway is
approximately 1/4 its vertical length.
Referring to Fig. 5, the colander 22 has a
cylindrical vertical side wall 101 and a horizontal per-
- forated bottom wall 102 for straining the water from the
beans. The colander is removably mounted on sump 24
(Fig. I) for collecting water strained through perfora-
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tions 103 in the bottom wall o~ the colander.
The sump means has a top wall 104, a bottom
wall 106, side wall 108, 110 and end walls 112, 114. The
top wall includes a large circular opening 115 beneath the
colander. Surrounding the opening is a rim 116 for
centering the colander. Spanning the opening are two
horizontal crossed members 118, 120 ~or supporting the
; colander. Bottom wall 106 is inclined downwardly in the
direction of end wall 114. Wall 114 has an outlet 122 at
its lower end.
Pipe 124 connects outlet 122 to pump means
26 for drawing water from the sump. The pump means
include~ an electric motor (not shown) drivingly
connected to a water pump 126.
Both the pump means and the sump are supported
at the bottom of frame 32 between four hoxizontal frame
members 128 defining sides o a rectangle. Four wheels
34 are connected to the frame, one at each corner formed
by the interconnections of frame members 128.
~he bean cleaners can be of small size to
enable easy storage and use in small areas, such as
restauxant kitchens. In one example, the bean cleaning
apparatus has an overall height of five feet and lateral
dimensions of two feet by thxee and one-half feet. In
such example, the separator tank has a diameter o~ 511
and the ~ertical distance along side wall 80 from bottom
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wall 82 to the bottom wall 98 o over~low means 20 is
8~'. The inner tube 64 has a diameter of 1~1/2" and outer
tube 68 has a diameter of 2", passageway 69 hauing a radial
width of about 1/8". The lower ends of the tubes are
spaced about 3/4" above bottom wall 82. The tubes are
preferably made of stainless steel, as is the colander,
for processing of human foodstuffs.
The bean cleaner of the foregoing example
was tested by manually removing "all" stones from loo
pounds of beans, "salting'i the beans with eight stones,
and cleaning the beans in the bean cleaner operated as
described below. After cleaning such beans, 15 stones
were recovered from the sepaxator tank.
operation of Apparatus
The bean cleaner is prepared for use by pivoting
feed tray 36 to a horizontal position and placing a sack
132 of beans 134 (E'ig. 6) thereon with its openirlg 136
positioned above the hopper's top opening 138. The sump
2A is filled with water .lA0 and the pump means 26 is
turned on. The beans are then dumped into the hopper and
vibrators 28 and 30 are turned on.
Vibrator 28 vibrates the hopper on its flex-
ible mounts 44 so that the beans descend in a continuous
flow through tube 50, as indicated in Fig. 2 by arrows
142. The beans flow downwardly in a continuous stream
through flexible fannel 66 into tube 64 and descend to
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central opening 92, as indicated by arrows 144. The
beans then drop from opening 96 toward the bottom of the
separator tank, as indicated by arrows 146. Vibrator 30
shakes tubes 64, 68 to help maintain a continuous down-
flow of beans through tube 64.
Meanwhile, pump 126 (Fig. 1) pumps water from
the sump through pipes 124 and 78 to connector 70. Such
water enters the connector through bore 76 and is distri-
buted within annular water passageway 69. The water
descends, under pressure, through the passageway to
annular opening 94, as indicated by arrows 148. The water
is expelled downwardly from annular opening 94 toward
the bottom of tank 24 at high velocity, as indicated by
arrows 150, entraining the discharged beans in the re-
sulting turbulent flow of water. The water a.nd beans
are deflected laterally, ~hen upwardly, by tank bottom
and side walls 80, 82, effecting a flow reversal.
The water thus fluidizes the heans as they
enter the tank through opening 92, conveys them later-
ally away from opening 92 and buoys them upward, as
indicated by arrows 152. The lateral, then upward,
flow of the water produces eddies E in the corner 154
defi~ned by sidewall 80 and bottom wall ~2. The abrupt
reuersal of the water flow also roils the water-bean
mixture considerably in the lower portion 153 of the
separator tank and to a progressively decreasing extent
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proceeding toward upper portion 155 o the tank.
Referring to Fig. 6, this roiliny action or
turbulence jostles or vibrates the beans and, thus, tend
to produce spaces between the beans 134 in lower tank
portion 153. Stones 154, discharged into the tank with
the beans, travel laterally with the flow of beans~ Some
of the stones are then initially conveyed upwardly by
the beans and water, while others are caught in eddies E.
The stones conveyed upwardly do not travel far before
losing momentum, typically less than half the vertical
distance to the spillway 20. They are slowed down by the
influence of gravity and by collisions with the more
densely packed beans in the upper region 155 of the tank
and, thus, begin to sift downward through -the spaces
between the beans toward the bottom of the -tank, as
indicated by arrows 156. Eventually the stones settle
along tank bottom wall 82.
The water flow rate is adjusted using valve
79 to assure that the stones are rel:iably separated
from the beans. If the flow rate is too high, some
stones may be borne upwardly with the beans to the spill-
way 20. If too low, both stones and beans will settle
to the bottom of the tank without being separated. The
correct flow rate is determined by visually observing
the action of the beans and stones in the separator tank.
The flow rate should be high enough that the aforemen-
tioned roiling action occurs in at least the lowerquarter of the separator tank below the spillway. The
flow rate should not be so high that the roiling action
extends to the surface of the water and beans. It is
preferable to have the roiling action encompass approx-
imately the lower one-half to two-thirds of the tank, the
flow rate beiny adjusted accordingly. Operated in this
range, the bean cleaner reliably removes all stones from
dried beans.
Vibration of conduits 16, 18 by vibrator 30,
as indicated by arrows 158, appears to aid in separating
the rocks from beans as well as shaking the beans down
~ube 30 by jostling the fluidized beans in the tank to
help produce spaces between the beans.
The upwardly-borne beans accumulate rock-
free in the upper portion 155 of the separator tank. Once
the tank has filled to the level of the bottom wall 98
of the spillway 20, the bean~ and water welling upwardly
from beneath cause the beans and water in upper portion
155 to over~low in a continuous stream into the colander
22. The beans are retained in the colander while the
water passes through the perforations 103 and openiny
115 into sump 24 to be recirculated.
The level of rocks in the tank is visually
monitored through the transparent walls of the tank.
When sufficient stones have accumulated to nearly cover
the bottom of the tank, or when a sack of beans has been
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643
cleaned, the pump is turned off, the tank is lifted
from pins 86 and the stones are removed. The tank is
then re-mounted on the pins. Colander 22 ls usually
emptied of beans at the same time. Thereafter, the bean
cleaner can resume operation.
When use of the bean cleaner is compl te, it
can be unplugged, and tray 36 pivoted to a down position.
The apparatus can then be rolled on wheels 34 to a
suitable storage location.
Bean cleaning method
Following is a description of the preferred
method of separating beans according to the invention.
The foregoing bean cleaning apparatus, operated as
described above, performs the steps of this method.
However, other apparatus may be used as well.
In the first step, beans are fed in a con-
tinuous column downwardly through conduit 64 ancl drop
through bean discharge opening 92 onto -th~ bottom wall
of separator tank 1~ ~arrows 144, 146). The beans 134
are discharged near the bottom of the tank to avoid
mixing them with previously cleaned beans above.
5econd, a continuous flow of water is dis-
charged downwardly under pressure in an annular pattern
from water discharge opening 94 surrounding opening 92,
as indicated by arrows 150. The beans are entrained in
the water and, thus, become fluidized.
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Next, the downward ~low of water is reversed
to create a lateral and then upward flow of water as
indicated by arrows 152. Being entrained in the water
the beans are conveyed laterally away from bean discharge
opening 92 and then born upwardly by the water.
Simultaneously with reversing the downflow
of water, a roiling action or turbulence is imparted
into the water flow in the lower portion 153 of the
tank. This action includes inducing eddies E adjacent
the bottom of the tank along side wall 80 for catching
and holding relatively heavier objects such as stones
154. The turbulence jostles or agitates the beans as
they flow upwardly, creating spaces between them for
the stones to sift downwardly between the beans.
The rate of water flow into the tank is
adjusted so that the beans, but not the stones, are
borne upwardly in the tank. rrhis adjustment can be made
by adjusting the velocity of the upward flow rate of
water to a rate greater than the velocity at which beans
sink in still water, giving the beans a net upward
velocity. For a tank of given cross-sectional area,
the upward flow rate is controlled by adjusting vàlve 79.
The upward flow of beans is then slowed, but
not entirely halted, by accumulating beans in an upper
portion 155 comprising about one-third to one-half of
the tank. Slowing the upward flow allows any stones 154
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initially borne upwardly by the water and beans to lose
momentum and begin to sink. Such stones sift downwardly
through the spaces between the agitated beans in the
lower portion of the tank and eventually come to rest on
the bottom of the tank.
Next, the beans and water accumulated in the
upper portion of the tank overflow the tank in a con-
tinuous stream (arrow 160)~ Finally, the water is
strained from the rock-free beans -(arrow 162~. The
water is collected in sump 24 and recycled by pump 126
back to the water discharge opening 94.
Ha~ing illustrated and described a preferred
embodiment of the invention, it should be apparent to
those skilled in the art that the invention may be
modified in arrangement and detail. We claim as our
invention all such modifications as come within the scope
of the followiny claims.
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