Note: Descriptions are shown in the official language in which they were submitted.
1~0355
Background of the Invention
This invention relates to the field of separators
and particularly to apparatus for removing particulate matter
from a gas on which it is born. Centrifugal separators using
the cyclone principal for this purposear2known, and it is
indeed known to construct two stage separators of this type.
They suffer however from several disadvantages when used to
remove ~rom air the dust encountered in the practice of the
mechanized rock drilling process, with high limestone content,
small mean particles size, and high concentration. Normal
clusters of small precisely dimensioned cyclone tubes plug
rapidly, while larger gross cyclone tubes do not provide the
needed separation efficiency. There is need for a separator
which removes gross amounts of dust with high efficiency.
Summary of the Invention
The present invention solves the problem by utilizing
an improved two sta~e separation process in a single body.
The particle-laden gas is admitted tangentially into the first
stage which removes most of the larger particles. The gas
then passes to the second stage through a plenum in which the
vortex energy of the gas is reinforced by the feedback vortex
from a helical element in the second stage. This arrangement
maximizes the centrifugal or separation energy obtainable from
a given fan or blower horsepower, and is accomplished by
angularly positioning the vane optimally, about the axis of
the apparatus, with respect to the location of the tangential
input. This arrangement has given up to 97% total separation
efficiency. It also lends to a very efficient and compact
arrangement for automatically discharging the collected particles
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1~0355
each time the flow of gas through the apparatus is interrupted, and this
arrangement is also a part of the invention.
The invention provides apparatus for removing particulate matter
from a gas on which it is borne comprising, in combination: a first
cylinder having a vertical axis, a lower end, and a closed upper end; a
second, concentric cylinder having a closed upper end and an open end pro-
ecting downward partially into the first cylinder; a third, concentric
cylinder having a lower end and an open end proiecting upward partially into
the open end of the second cylinder; a fourth, concentric cylinder having an
1~ open end pro~ecting downward partially into the open end of said third
cylinder and an open end pro~ecting through the top of said second cylinder
to comprise the gas outlet for the apparatus; input means for admitting gas
bearing particulate matter tangentially into the first cylinder to cause
vortical gas movement in the first cylinder; a helical partition extending
downwardly in the space between said third and fourth cylinders, the downward
direction of the helix being the same as the direction of the vortex in the
first cylinder, said helical partition being angularly positioned, about said
axis, relative to the location of said longitudinal input, for maximum
conservation of vortical momentum of the gas; and means at the lower ends of
the first and third cylinders for gravitationally receiving particulate
matter centrifugally driven to the inner walls of the cylinders.
~arious advantages, and features of novelty which characteriæe our
invention are pointed out with particularity in the claims annexed hereto and
forming a part hereof. However, in a better understanding of the invention,
its advantages and objects attained by its use, reference should be had to
the drawing which forms a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a preferred
embodiment of the invention.
Description of the Drawing
In the drawing Figure 1 is a plan view of apparatus embodying the
invention;
Figure 2 is an elevation of the apparatus, parts being broken away
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for clarity of illustration;
Figure 3 is a section along the lines 3-3 of Figure 2;
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Figure 4 is a section along the line 4-4 of Figure 2;
Figures S and 6 are fragmentary views of a portion
of the apparatus, partially in section;
Figure 7 is a section on the line 7-7 of Figure 6;
and
Figure 8 is a section on the line 8-8 of Figure 2
showing the operation of a portion of the apparatus.
Description of the Preferred Embodiment
Turning now to the drawing, the invention is seen to
comprise a plurality of coaxial cylinders 10, 11, 12 and 13 of
sheet metal. A plenum 14 is arranged to supply gas laden with
particulate matter into cylinder 10 along an element 15 of the
cylinder. The top of cylinder 10 is closed to comprise a
downwardly helical surface 16.
Cylinder 11 has an open end 17 that projects down-
wardly into cylinder 10 and is closed at its upper end by a
domed cap 20 which projects above top 16 of cylinder 10.
Cylinder 12 has an open upper end 21 which projects
upwardly into cylinder 11. The lower end of cylinder 12 is
reduced in diameter at 22, and is supported in cylinder 10 by
diagonally mounted braces 23.
Cylinder 13 has a first open end 24 which projects
downwardly into cylinder 12, and a second open end 25 which
projects upwardly through cap 20 of cylinder 11 to comprise
the outlet for the apparatus.
A helical vane or partition 26 extends downwardly
in the space between cylinders 12 and 13. The downward slope
of partition 26 is in the same direction as that of helical
surface 16.
Cylinder 10 is surrounded at its base by a cover
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plate 27 and rests, with its axis vertical, on a hopper
structure comprising a pair of side walls 30 and 31, front
and rear walls 32 and 33, and a mounting angle 34 extending
between side walls 30 and 31. A sloping bottom plate 35
completes the hopper, into which particulate matter falling
from the cylinder is received, the hopper comprising a central
chamber 36 bounded by the reduced extension 12a of cylinder 12,
for receiving particles from cylinders 12 and 13 and partition
26, and a separate outer chamber 37 for receiving particles
falling from cylinders 10 and 11. A counter-weighted door
40 is provided in bottom plate 35 to permit matter collected
in chamber 36 to be discharged, and a second door 60 is
provided at the bottom of front wall 32, to permit discharge
of matter collected in space 37.
As shown in Figures 2 and 6, door 40 comprises a
plate 41 having a pair of ears 42 bored to pass a pin 43
which is pivoted in a tube 44 welded across a leaf 45 of a
T-hinge 46: the other leaf 47 is secured bo bottom plate 35
as by bolts 50. A threaded rod 51 is secured to leaf 45 at
~0 an appropriate angle, and carries a counter-weight 52 which
~ay be locked in adjusted position along the rod by a nut 53.
A suitable gasket 54 completes the seal when door 40 is closed.
~he end of leaf 45 projects beyond tube 44 at 55 to limit the
pivotal motion of plate 41.
It will be appreciated that when the apparatus is
in operation the external atmosphere exerts a force on plate 41
in a direction to maintain the door closed. Counterweight 52
is adjusted to just close the door when no particulate matter
is in chamber 36 and the apparatus is not in operation: then
if such matter does collect, its mass is opposed by the
positive external air pressure as long as the apparatus is in
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operation. When air flow out of the apparatus ceases the positive
pressure disappears, and the weight of material on plate 41 opens
door 40, discharging the collected matter, after which the
counterweight again loosely closes the door.
Door 60 is so located that a counterweight arm extend-
ing outwardly therefrom would be inconvenient, and an alternative
self closing structure is used. As shown in Figures 2 and 7
the lower front edges of sides 30 and 31 are not vertical, but
tapQr backward slightly. As shown in Figures 5 and 8, the
opening defined by walls 30, 31, 32 and plate 35 is surrounded
on three sides by a channel 61 which is connected by a T-pipe
62 with extention 12a. A door panel 63 is made up of an inner
layer 64 of soft material, and intermediate layer 65 of stiffer
yet still flexible material, and an outer reinforcing layer 66
of material stiff enough to prevent collapse of the materials
under pressure differential, the layers being secured together
by suitable means such as rivet 67. Layers 64 and 65 project
upwardly from the panel and are clamped to front wall 32 by a
plate 68 and screws 69, to form a hinge.
In the absence of positive external pressure, door
panel 63 hangs vertically, as shown in ~igure 7, and indeed may
be pushed outward to allow material in chamber 37 to be dis-
charged. When air flow through the apparatus resumes, a negative
pressure quickly appears in chambers 36 and 37, and chamber 36
acts through T-pipe 62 and channel 61 to create a flow of air
past door panel 63 which swings the do~r shut: it is held there
against the weight of gathering of particulate matter until the
air flow through the apparatus is discontinued, when discharge
of the material again takes place. The venting of channel 61
through T-pipe 62 into chamber 36 of high negative pressure
insures high p~èssure differential across door panel 63 at the
outer edges to hold the door closed against the large amount
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o~-con~ami~ah~iico}~ected in Ghambe~37O ~ Figure 7 shows
the apparatus with both doors in the discharge positions. In
practice it is found that not enough material gathers in
chamber 36 during normal use spans of the apparatus to cover
the inlet to T-pipe ~2, and in any event the chamber 37 is
also at a negative pressure, if perhaps not so great a one as
chamber 36.
In one embodiment of the invention the gas to be
cleaned was supplied to input plenum 14 through a flanged
vertical riser 70 connected to the lower corner of the plenum
as seen in Figures 1 and 2.
Operation
In use our apparatus is mounted as described, riser
70 is connected to a source of gas bearing particulate matter
to be removed, and outlet 25 is connected to a pump or blower
which draws gas out of the apparatus. The flow of gas through
the apparatus is as shown by the arrows in Figures 2 and 4; a
counter clockwise vortical flow occurs inside cylinder 10 which
urges the particles toward the wall of the cylinder, down
which they drop to chamber 37. In the upper part of
cylinder 10 the helical surface redirects the flow of gas in
this portion of the cylinder downwardly. The cleaner gas
near the axis of the cylinder passes up through the space
batween cylinders 11 and 12 into the plenum 72 defined by
cap 20. The gas next passes between cylinders 12 and 13,
following the helical path defined by partition 26. The
area of the channel is less here, so the gas volocity is
greater, and partition 26 adds a further vortical component
to that already p~ssessed by the gas, so that remaining
particles, mostly of smaller mass, are again urged to the
wall of the cylinder, this time of cylinder 12, and drop
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therefrom into chamber 36. The cleaned gas passes through
opening 24 and out at tube 13, it still may have considerable
vortical energy but this is without significance.
The inner walls of cylinders 10 and 12 are two of the
principal areas for collecting particulate matter, but some does
come to the inner wall of cylinder 11. ~hen this occurs, and
as it develops sufficient mass in the contaminant swirl, it will
drop from the open end 17, and be carried vortically to cylinder
10 .
A feature of the invention which is of considerable
importance relates to the known fact that when a stream of gas
approaches a structure such as partition 26, there is produced
not only a vortex down stream from the partition, but a "fore"
or "feedback" vortex upstream of the partition. The angular
relation, about the axis of the cylinder, between the leading
edge 73 of partition 26 and the point of tangency 74 of plenum
14 is carefully chosen so that the "feedback" vortex does not
oppose or enturbulate the input vortex, but rather augments it.
In one form of the invent~on it was found that the former
~0 should be advanced by 360 from the latter, but it will be
understood that different dimensions of the cylinders, or a
different flow rate through the apparatus, may dictate some
other angular relation.
It should also be pointed out that the presence of
plenum 72 is important to optimum operation of the apparatus:
the plenum must be at least sufficiently large to prevent
significant turbulance from interfering with the air flow
from cylinder 10 to partition 26.
From the foregoing it will be evident that the
inventive contribution disclosed here is an improved two stage
centrifugal apparatus for separating gas and particulate
matter, the improvement residing in part in the provision
355
of a plenum between the stages, in part in position-
ing a vortex enhancing element in the second stage in a proper
angular relationship, about the axis of the apparatus, relative
to the vortex inducing portion of the first stage, and in part
in providing means minimizing the maintainance of the apparatus
by automatically discharging particulate matter gathered
during each operation of the apparatus.
Numerous objects and advantages of our invention
have been set forth in the foregoing description, together
with details of the structure and function o the invention,
and the novel features thereof are pointed out in the
appended claims. The disclosure, however, is illustrative
only, and changes may be made in detail especially in matters
of shape, size, and arrangement of parts,within the principle
of the invention, to the full extent indicated by the broad
general meaning of the terms in which the appended claims
are expressed.
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