Note: Descriptions are shown in the official language in which they were submitted.
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~ck~round o~ the Invention
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This invention relates to a limp, porous membrane of
sheet or cloth material or a 1uidized ou~le~. ~ore
speciflcally, this invention relates to the ~luidized outlet Oe a
coveeed hopper railway car.
Generally, when unloading a bulk pulverant, powdered, or
particulate lading from a hopper, such as a hopper o~ a covered
hopper cae, such ladings have a tendency to bridge and column
inside the hopper. In order to continue the unloading, it is a
common practice to vibrate or hammer on the outside of the
hopper, thereby to dislodge the bridged and columned lading. It
is also conventional to use probes inserted into the lading rrom
above to break up the bridges and columns within the 1ading.
It has been known that by using a 1uidized outlet built
into the bottom o the hopper, fluidizing fluid (e.g., air under
relatively low pressure, S-15 psi) flowing through a fluidizing,
porous membrane and into the powdered or particulate lading 1n
contact w1th the membrane would cause the lading to ~e 1uid zed
so that the lading would flow as freely as a liq~id. This
resulted in faster and much more eficient unloading of the
railway hopper car.
As shown in the co-assigned U.S. Patents 4,280,706 and
4,568,244, i.ssued in April, 1981 and April, 1986, respectively,
prior art fluidizing membranes conventionally comprised a
porous screen or the like made of .fine mesh stainless
steel. However, while stainless steel fluidizing membranes were
relatively impervious to moisture pick-up, could be readily
cleaned, and weee long-lasting, they were relatively expensive,
both to install and to replace if necessary. ~n a larger size o
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outlets where the outlet had both side and end walls converging
inwardly and downwardly from the centraL lower outlet opening,
the stainless steel membrane was often formed in one piece so as
to be disposed on the inside faces of the end and side walls.
During unloading, particularly upon exhausting of all or
substantially all of the lading from within the hopper, the
stainless steel mesh, which was relatively rigid, had suficient
force to withstand the static air pressure behind the porous
membrane in the outlet walls without damage to the porous
membrane.
It has long been recognized that limp fabLic membranes
could be used in place of the stainless steel membranes with
large attendant cost savings. However, cloth membranes were
rela~ively difficult to seal at ~he connection o~ the
cloth membrane and the outlet frame and to the outlet opening at
the bottom proximate the outlet opening. In addition, cloth
membranes o~tentimes did not have sufficient strength to
withstand the static air pressure therebehind when the lading was
nearly withdrawn from the outlet. It will be appreciated that
the static air pressure would tend to "balloon" the membrane
matexial away from the walls of the outlet when the hopper was
substantially free o~ the lading thus putting undue tearing
~orces on the membrane where it joined the outlet frame and the
bottom outlet As a conse~uence, oftentimes, fabric membranes
were only used in relatively small panels in which the cloth
membrane could be secured around its periphery to a rigid metal
frame, such as shown in the co-assigned U.S. patent 4,280,706.
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Thus, there has been a long-standing need for a
relatively inexpensive, limp cloth fluidizing membrane which could
be used on large fluidized outlet walls and surfaces which did not
experience undue ~ballooning~ when pressurized such that the
membrane would remain attached to the outlet, both at the outlet
frame and at the outlet opening.
Summar~ of the Invention
Thus, according to the present invention, there is
provided a limp, porous membrane o~ flexible sheet material for
use with a fluidized outlet, said outlet being in communi.cation
with a container, such as a hopper, containing a supply of a
particulate lading Eor being fluidized and unloaded via said
outlet. The outlet comprises an outlet housing having an outlet
frame for securing said outlet to said hopper, an outlet opening,
and outlet walls extending from said frame to said outlet
opening. The membrane is secured to said outlet frame and to said
outlet opening and is disposed generally on the inside face of
said outlet walls. Means are provided for introducing fluidized
fluid undar pressure between said outlet walls and said membrane
such that fluid flows through said membrane so as to fluidize said
lading. Means are also provided, carried by said membrane
extending generally from said outlet ~rame to said outlet opening,
for holding said limp membrane generally in face-to-face relation
with said outlet walls at least in the areas of said holding means
during fluidization of said lading.
Notable amongst the advantages to be realized by the
present invention are the following:
The use of limp, porous (for example, cloth) membranes
which will hold their shape, in place of more expensive stainless
steel membranefi for use with a wide variety of pulverant,
particulate ladings.
The use of limp porous membranes as recited which will
resist "ballooning" forces when exhaustion of the lading from
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within the hopper is near complete, and when fluidizing fluid
remains connected to the fluidization system.
The use of a limp fluidizing membrane which may be
readily incorporated in a number of outlets of various size6,
which is of cugged construction, which is reliable in operation,
which may be readily cleaned, and which has a long service life~
The invention will now be described further by way of
example only and with reference to the accompanying drawings.
Brief Description of_~he Drawinqs
FIG. 1 is an exploded view of a fluidized outlet for a
railway hopper car. showing a membrane assembly of the pre6ent
invention;
FIG. 2 is a top plan view of the membrane assembly;
FIG. 3 is a side elevational view of the membrane
assembly;
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FIG. 4 is a cross sectional view, taken along line 4--4
of FIG, 2, illustrating, on an enlarged ssale, means carried by
the membrane assembly for holding the membrane assembly in place
relative to the walls of the outlet;
FI~. S is a vertical cross sectional view of an outlet
boot of the membrane assembly, taken along line S--5 of FIG. 2;
and
FIG 6 is a cross setional view, taken along line 6--6
of FIG. 2, illustrating the gasket on an enlarged scale utilized
to seal the porous membrane between the outlet frame and the
hopper frame.
Corresponding reference characters indicate
corresponding parts throughout the several views of the drawing.
Description of a Preferred Embodiment
Referring now to the drawings, and particularly to FIG.
1, a pneumatic, fluidized outlet lS indicated in its entirety by
reference charac~er 1. This outlet 1 is adapted to be bolted to
the lo~er portion of a hopper ~not s;hown), such as a hopper of a
covered hopper railway car utilized ~o transport a wide variety
o~ bulk particulate, powdered, granular, or other pu~verant
ladings. It will be appreciated that within the broader aspects
Q~ the present invention, the term "particulate" is used
generally to refer to any powdered, granular, or other dry,
~lowable lad ing .
More specifically, outlet 1 is shown to comprise an
outlek housing 3, having an outlet frame 5 at its upper end, and
an outlet opening 7 at its lower center portion. The outlet
further has a plurality of outlet end and side walls 9 and 10,
respectively, sloping inwardly and downwardly from outlet frame 5
toward outlet opening 7, As indicated at 11, so-called valleys
are formed at the intersections between the side and end walls.
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In accordance with this invention, a fluidizing membrane
assembly, as generally indicated at 13, is provided on the inside
~aces of the outlet walls 9 and 10. Means 15, reerred to as a
fluidizing air manifold, is provided for introducing a fluidizing
medium (i.e., air under pressure) between the outlet walls 9 and
10 and fluidizing membrane 13, such that the fluidizing medium
will ~low through the porous membrane and tend to 1uidize the
lading in close proximity to the membrane, such that the ladiny
will flow, as a liquid, downwardly over the inner surfaces of the
membrane toward outlet opening 7, thus greatly facilitating the
unloading of pulverant material from within the hopper. A
fluidizing air distribution manifold 17 may optionally be
provided between outlet walls 9 and 10 and fluidizing membrane 13
so as to be in communication with means lS so as to distribute
the 1uidized medium between the o~tlet walls and the membrane
assembly 13.
As indicated at 19, an outlet manifold is secured to the
bottom portion of the outlet walls so as to be in communication
with outlet opening 7 such that the fluidized lading may be
removed from the outlet in any conventional manner, such as by
pneumatic ~onveying, or the like. It is intended that outlet 1
is a pressure diferential outlet such ~hat elevated pressure of
a predetermined level (e~g., S psi) may be exerted upon and
maintained wi~hin the hopper o~ the hopper car. Fluidizing air
int~oduced into outlet 1 via fluidizing means 15 and manifold 17
will, o~ necessity, be of a somewhat higher pressure level so
that the ~luidizing air will ~low freely through membrane 3 and
~luidize the lading in close proximity to the membrane, Upon the
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lading being fluidized and flowing downwardly for unloading via
outlet opening 7, the elevated pressure within the hopper forces
the fluidi~ing lading out of manifold lg and into a conduit (not
shown) ~or pneumatically conveying the lading away from the
outlet. An outlet control valve 21 is provided for regulating
the flow of lading f~om the outlet. A fluidizing air bypass
valve 23 is provided between fluidizing air manifold 15 and
outlet manifold 19 such that the amount of fluidizing air
admitted into distribution manifold 17 for fLuidizing the
lading may also be regulated.
Refe~ring now to FIGS. 2~6, the 1uidizing membrane
assembly 13 is shown to comprise a gasket 25 around its upper
edge with a cloth membrane, as indicated at 27, secured
lstitched) to the gasket, as indicated at 28 (see FIG. 6).
Gasket 25 comprises upper and lowe~ gasket members 2~ with an
elastomeric s~rip 31 therebetween. Securement bolt holes 33 are
provided at desired spaced locations (as shown in FIG. 2) such
that the gasket may be bolted between outlet frame 5 and a
corresponding hopper frame (not shown). For example, the gasket
material may be constructed in accordance with the gasket
disclosed and claimed in the co-assigned U.S. patent 4,428,585
Membrane assembly 13 further comprises generally
trapezoidal side panels 35a, 35b disposed on opposite sides o
the membrane, and end panels 37a, 37b at opposite ends of the
membrane assembly. The membrane side and end panels are disposed
to be generally in face-to-face contact with the inside
respective faces of outlet side and end walls 9 and 10. Further,
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the membrane side and end panels are joined together along
membrane panel intersections, as generally indicated a~ 39, which
in the outlet frame in ~IG. 1, tend to overlie valleys 11 between
outlet walls 9 and 10. A boot assembly 41 is secured to the
lower margins of the side and end panels, in the manner
illustrated in FIG. 5, such that the membrane assembly may be
rigidly connected to outlet housing 3 surrounding the outlet
opening 7. The boot includes a gasket 43 (as best shown in FIG.
S) at the lower margin thereof for being rigidly secured to the
lower portion of the outlet housing.
In accordance with this invention, a membrane stiffener,
as generally indicated at 4S, is carried by the permeable
membrane generally at the locations of the intersections 3~ so as
to support the membrane side and end panels between gasket 25 and
boot 41 thereby to prevent undue "ballooning" of the side and end
panels during fluidization, and more particularly when the lading
is substantially unloaded therefrom and when fluidizing air
continues to enter via the fluidizlng air inlet means 15. More
specifically, each membrane stiffener, as shown in FIG. 4,
comprises an elongate, rigid rod 47 of suitable metal (e.g.,
s~ainless steel or the like) which is held captiva within
overlapping panel portions 49 of the side and end panels 35a, 35b
anad 37a, 37b, respectively, which are stitched together along
lines of stiching 51.
In this manner, with fluidizing membrane assembly 13
disposed on the inside faces of outlet housing walls 9 and 10,
with gasket 25 secured between outlet frame 5 and the hopper
frame (not shown), and with boot 41 secured to the bottom of the
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outlet frame, membrane stiffeners 45, and par~icularl.y rods 47,
hold the intersecting edges of the side panels 35a, 35b and the
end panels 37a, 37b in close proximity to the inner faces o the
outlet walls in the general proximity o~ valleys lL without
placing undue stresses or tear-out forces on the fabric membrane
adjacent gasket 25 or boot 41. However, those skilled in the art
will appreciate that the membrane stiffeners 45 of the present
invention do permit a limited amount of "ballooning" action of
the flexible membrane between the stiffeners which aids in
clean out of the outlet by forcing any residual lading clear of
the membrane and to fall into the outlet opening.
In this manner, a porous, limp cloth membrane can be
utilized on large size outlets in place of rigid and more
expensive stainless steel mesh outlets, without the necessity of
the outlet membLane being divided lnto small panels and secured
around all of the edges to the outiet frame. AdditionalLyl a
more complete clean-out of the paLticulate Lading materiaL is
possible.
As various changes could be made in the above
constructions without departing from the scope of the invention,
it is intended that all matter contained in the above description
or shown in the accompanying drawing shall be interpreted as
illustrative and not in a limiting sense.
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