Note: Descriptions are shown in the official language in which they were submitted.
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The present invention relates to a bin or hopper
havin~ a discharger or reclaimer at the bottom, More speci-
fically, the present lnvention i5 directed to a load supportin~
grid structure iD a bin or hopper ha~ing a discharger or
reclai~er at the bottom thereo~,
When material such as wood chips or hogged fuel are
stored in a deep bin or hopper they tend to pack down with the
resulting increase in denslty of the material at the bottom~
causing separate pieces to lock ~ogether, When ma~erial is then
removed from underneath this bin or hopper, bridging o~ these
locked pieces occurs resulting in cavities in the packed material
which prevents discharge from the bin or hopper. These cavities
cause interruption in the normal discharge of material from the
bin or hopp~r, To restore normal operations, such devices as
air cannons and vibrators have been used to break up the bridged
material and prevent cavities from being formed. Such devices
are troublesome and not always effective.
In deep bins or hoppers the entire weight of material
be~ng stored ~s presently supported by the ~loor. In many
cases the floor has a discharger, such as a live bottom stoker
discharger, a live bottom screw discharger, or a live bottom
chain discharger. When the entire weight of the material rests
on the floor and discharger, tremendous forces are neces~ary to
move the material and the power to operate the discharger is high
due to the pieces of material being sheared against and through
adjacent pieces of material. The discharge o~ solld materials
requires high unit shear pressures resulting in high power re-
quirements for the discharger mechanisms.
It is a purpose of the present lnvention to reduce the
material weight on the floor of bins and hopper~. It is also
a purpose to provide a bin or hopper ~or solid materlals with
a discharger or reclaimer at the bottom, that avoids the problems
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of bridging and cavi~ies in the packed material causin~ inter-
ruptions in the discharge.
The present invention provides in a bin or hopper ~or
storing solid materi~ls to a depth o~ at least 20 feet, the
bin or hopper having a discharger means at the bottom thereo~,
the improvement comprising a load supporting grid structure in
the bin or hopper positioned above the dlscharger means to
support the welght o~ at least a portion o~ solid materials in
the bin or hopper.
In other embodlments the grid structure i5 located in
the approximate range of 2 - lO feet above the bottom of the
bin or hopper, and the grid structure is formed of I-beams. If
the bin or hopper is used for wood chips, then preferably the
structure is ~ormed of beams perpendicular to each other at a
distance apart in the approximate range of 8 - 14 feet. If the
bin or hopper is to be used ~or hogged fuel, the grid structure
is formed ~f beams perpendicular to each other at a distance
apart in the approximate range o~ 12 - 14 feet.
In drawings which illustrate the embodiments of the
inventlon,
Fig. 1 is a cross sectional side view o~ a hopper
having a load supporting grid structure according to one embodi-
ment of the present invention
Fig. 2 is a sectional view at line 2-2 of Fig. l.
Referring now to the drawings, a bin or hopper 10
having tapering sides 11 so that the top is narrower thar~ the
base, has a live bottom stoker 12 on the floor 13, which dis-
charges material through a discharge opening 14 beneath a shear
beam 15 in one side of the hopper lO. The material drops into
a trough 16 having a screw conveyor 17 therein.
The live bottom stoker 12 shown in the dra~ings is
a reciprocating mechanism having stoker ~ross bars 18 mounted
,t;,
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on two reci.procating longitudinal stoker arm~ 19 with ~ixed
eross bars 20 therebetween. The stoker cross bars 18 are
tapered at one side, 90 that the material is pushed when the
cross bar 18 moves in one direction, and then slides under the
material on the return stroke The ~ixed cross bars 20 prevent
the material moving backwards when the stoker cross bars 18 are
on the return stroke ~s illustrated in Fig. 2, a plurality of
mechan~sms are mounted side by side with adjacent stoker
mechanisms 12 reciprocating out of phase with ea~.h other, to
assist in the preventing of bridging or plugging o~ the solid
materials. One example o~ such a discharger mechanism is
illustrated in U.S. patent 4,157,761 to Debor, issued June 12,
1979.
In the embodiments shown in the figures, the dis-
charge exits at one end of the bin or hopper, however, the bin
or hopper may be arranged to have exits at either end or both
ends, or even in the center. If a live bottom screw is installed
in place of the stoker mechanism, then this may be a fixed screw
with a plurality o screw feeds along the bottom of the hopper.
Alternatively, there may be a movable linear gear drive or
linear chain drive reciprocating a single screw feed to empty
the hopper. There may also be a rotating chain drive for
reciprocating a single scrPw feed across the floor of the hopper,
or a live bottom chain reclaimer, wherein a chain drags links
across the floor of the hopper.
A structural steel grid 21 is shown comprising cross
beams substantially perpendicular to each other, having the top
surface o~ all the beams in the same plane with the bottom of
the structural steel beams being in line with the shear beam 15.
The structural grid 21 is pre~erably made o~ I-beams or other
standard structural members, such as channels, wide ~lange beams,
etc. The structural grid is designed to support at least a
-- 3 --
a~ssol2
portion of the solid materials in the hopper. The steel grid
21 extends beyond the sides 11 of the bin or hopper 10 as shown
in Fig. 2 and has a supporting structure (not shown) to transfer
the weight of the material above the steel grid 21 away from the
floor 13 of the hopp~r 10 In this manner the weight of the
material on the floor 13 of the hopper 10 represents the material
between the floor 13 and ~he s~eel grid 21, plus some additional
weight of the material in the spaces of the grid structure.
Intermediate columns 22 are located at the intersections of the
steel grid and extend down between the stoker mechanisms 12.
Structural supports (not shown) beneath the floor support the
columns 22 and hence the grid structure 21. Such a grid is
useful when the depth of material in the hopper is 20 feet or
more. Less than 20 feet produces little advantage because the
loading from such a height does not substantially affect the
power requirement of the discharger mechanism and bridging or
plugging of the material does not often occur. The spaces
between the beams are sufficient to permit the passage of solid
materials to pass through down to the discharger mechanism, and
also sufficient to prevent bridging occurring in the packed
material to restrict material dropping down to the discharger
mechanism.
In the embodiments shown, the bottom o~ the structural
steel grid 21 is shown to be in line with the shear beam 15.
This is not essential, there are some applications where the
grid is located closer to the ~loor than the shear beam, and in
a preferred embodiment the grid structure is located in the
approximate range of 2 - 10 feet above the floor 13 of the bin
or hopper.
The spacing of the structural steel grid 21 varies
depending on the materials to be stored in the bin. For example,
wood chips should preferably have beams with a center distance
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apart in the approximate range of 8 - 14 ~eet. In the case of
hogged fuel, the grid structure is formed o~ beams substantially
perpendicular to each other with a center distance apart in
the approximate range of 12 - 14 ~ee~. Other materials require
dif~erent spacing depending on their tendency to pack together
and bridge. Examples of other applications include, sawdust,
municipal waste, shavings, logs and hogged ~uel, and other types
of shredded waste residues including bark.
In operation when the bln is filled with solid
materials, a large portion of the weight of the material above
the grid structure i9 supported by the grid structure, thus this
means that the weight o~ material on the discharger mechanism
represents only a small portion o~ the weight of material in
the bin. This means that the operation of the discharger
mechanism does not require the same power to move the material
as it would were the full head of solid materials resting on
the floor of the bin,
In one example a storage bin was made to store and
discharge spruce and balsam wood chips, The bin was 48 ft. wide
40 ft. long and 50 ft. high and has a storage volume of over
100,000 cubic ~eet when filled to capacity. The discharge
mechanism consisted of eight live bottom stoker mechanisms which
were designed to have adjacent stoker mechanisms reciprocating
out of phase with each other. The wood chips have a density of
about 1~ to 20 lbs/cu.ft. and the range of discharge from the
stoker mechanisms is in the range o~ about 618 to 4125 cubic
feet per hour or about 10,000 to 80,000 lbs. per hour.
The stoker mechanisms are each 5~ ft. wide by 40 ft.
long, each unit is powered by tour 6'~ diameter hydraulic cylinders.
The bin is equipped with a structural steel grid made from
W21 x 73 structural steel beams with spacings of 10 ~t. centers
from front to back and 12 ft. 4 i~ centers across the width
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of the bin, The top surface of the grid is approximately 8 ft,
above the floor of the bin, allowing a height distance :from
the grid to the top of the bin of 50 ft, The width of each
steel beam is approximately 8~ inches,
Various changes may be made to the steel grid 21,
The width of the top surface of the beams is selected to suit
the material stored in the bin, as is the spacing between the
beams, The support for the grid 21 is preferably separate
from the hopper or bin, The scope of the present invention is
limited only by the claims,
