Note: Descriptions are shown in the official language in which they were submitted.
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Title: TERMINAL INSERT FOR A CYCLONE SEPARATOR
FIELD OF THE INVENTION
This invention relates to an improved apparatus for
separating a component from a fluid stream. In one embodiment, the
fluid may be a gas having solid and/or liquid particles and or a second
gas suspended, mixed, or entrained therein and the separator is used to
separate the particles and/or the second gas from the gas stream. In an
alternate embodiment, the fluid rnay be a liquid which has solid
particles, and/or a second liquid and/or a gas suspended, mixed, or
entrained therein and the separator is used to remove the solid
particles and/or the second liquid and/or the gas from the liquid
stream. The improved separator may be used in various applications
including vacuum cleaners, liquid/liquid separation, smoke stack
scrubbers, pollution control devices, mist separator, an air inlet for a
turbine engine and as pre-treatment equipment in advance of a pump
for a fluid (either a liquid, a gas or a mixture thereof) and other
applications where it may be desirable to remove particulate or
material contained in a fluid.
BACKGROUND OF THE INVENTION
Cyclone separators are devices that utilize centrifugal
forces and low pressure caused by spinning motion to separate
materials of differing density, size and shape. Figure 1 illustrates the
operating principles in a typical cyclone separator (designated by
reference numeral 10 in Figure 1) which is in current use. The
following is a description of the operating principles of cyclone
separator 10 in terms of its application to removing entrained particles
from a gas stream, such as may be used in a vacuum cleaner.
Cyclone separator 10 has an inlet pipe 12 and a main body
comprising upper cylindrical portion 14 and lower frusto-conical
portion 16. The particle laden gas stream is injected through inlet pipe
12 which is positioned tangentially to upper cylindrical portion 14. The
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shape of upper cylindrical portion 14. and frusto-conical portion 16
induces the gas stream to spin creating a vortex. Larger or more dense
particles are forced outwards to the walls of cyclone separator 10 where
the drag of the spinning air as well as the force of gravity causes them
to fall down the walls into an outlet or collector 18. The lighter or less
dense particles, as well as the gas medium itself, reverses course at
approximately collector G and pass outwardly through the low
pressure centre of separator 10 and exit separator 10 via gas outlet 20
which is positioned in the upper portion of upper cylindrical portion
14.
The separation process in cyclones generally requires a
steady flow free of fluctuations or short term variations in the flow
rate. The inlet and outlets of cyclone separators are typically operated
open to the atmosphere so that there is no pressure difference between
the two. If one of the outlets must be operated at a back pressure, both
outlets would typically be kept at the same pressure.
When a cyclone separator is designed, the principal factors
which are typically considered are the efficiency of the cyclone
separator in removing particles of different diameters and the pressure
drop associated with the cyclone operation. The principle geometric
factors which are used in designing a cyclone separator are the inlet
height (A); the inlet width (B); the gas outlet diameter (C); the outlet
duct length (D); the cone height (Lc); the dirt outlet diameter (G);and,
the cylinder height (L)
The value d50 represents the smallest diameter particle of
which 50 percent is removed by the cyclone. Current cyclones have a
limitation that the geometry controls the particle removal efficiency
for a given particle diameter. The dimensions which may be varied to
alter the d50 value are features (A) - (D), (G), (L) and (Lc) which are
listed above.
Typically, there are four ways to increase the small particle
removal efficiency of a cyclone. These are (1) reducing the cyclone
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diameter; (2) reducing the outlet diameter; (3) reducing the cone angle;
and (4) increasing the body length. If it is acceptable to increase the
pressure drop, then an increase in the pressure drop will (1) increase
the particle capture efficiency; (2) increase the capacity and (3) decrease
the underflow to throughput ratio.
In terms of importance, it appears that the most important
parameter is the cyclone diameter. A smaller cyclone diameter implies
a smaller d50 value by virtue of the higher cyclone speeds and the
higher centrifugal forces which may be achieved. For two cyclones of
the same diameter, the next most important design parameter appears
to be L/d, namely the length of the cylindrical section 14 divided by the
diameter of the cyclone and Lc/d, the length of the conical section 16
divided by the width of the cone. Varying L/d and Lc/d will affect the
d50 performance of the separation process in the cyclone.
Typically, the particles which are suspended or entrained
in a gas stream are not homogeneous in their particle size distribution.
The fact that particle sizes take on a spectrum of values often
necessitates that a plurality of cyclonic separators be used in a series.
For example, the first cyclonic separator in a series may have a large
d50 specification followed by one with a smaller d50 specification. The
prior art does not disclose any method by which a single cyclone may
be tuned over the range of possible d5o values.
An example of the current limitation in cyclonic separator
design is that which has been recently applied to vacuum cleaner
designs. In United States Patent Numbers 4,373,228; 4,571,772;
4,573,236; 4,593,429; 4,643,748; 4,826,515; 4,853,008; 4,853,011; 5,062,870;
5,078,761; 5,090,976; 5,145,499; 5,160,356; 5,255,411; 5,358,290; 5,558,697;
and RE 32,257, a novel approach to vacuum cleaner design is taught in
which sequential cyclones are utilized as the filtration medium for a
vacuum cleaner. Pursuant to the teaching of these patents, the first
sequential cyclone is designed to be of a lower efficiency to remove
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only the larger particles which are entrained in an air stream. The
smaller particles remain entrained in the gas stream and are
transported to the second sequential cyclone which is frusto-conical in
shape. The second sequential cyclone is designed to remove the
smaller particles which are entrained in the air stream. If larger
particles are carried over into the second cyclone separator, then they
will typically not be removed by the cyclone separator but exit the
frusto-conical cyclone with the gas stream.
Accordingly, the use of a plurality of cyclone separators in
a series is documented in the art. It is also known how to design a
series of separators to remove entrained or suspended material from a
fluid stream. Such an approach has two problems. First, it requires a
plurality of separators. This requires additional space to house all of
the separators and, secondly additional material costs in producing
each of the separators. The second problem is that if any of the larger
material is not removed prior to the fluid stream entering the next
cyclone separator, the subsequent cyclone separator typically will allow
such material to pass therethrough as it is only designed to remove
smaller particles from the fluid stream.
In cyclone separators, substantial rotational velocities are
achieved, particularly in separators designed to remove finer particles
from a fluid stream. In some applications, such rotational velocities
may re-entrain separated material if it impinges upon the separated
material. For example, if the cyclone separator is vertically disposed
and designed to remove solid particulate matter from a fluid stream,
some of the separated particulate matter may accumulate at the bottom
of the cyclone separator. If the fluid stream impinges upon this
separated material, it may re-entrain some of the separated particulate.
SUMMARY OF THE PRESENT INVENTION
In accordance with the instant invention, there is
provided a terminal insert for a cyclone separator for separating a
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material from a fluid, the separator having a longitudinally extending
body and a wall, the wall having an inner surface and defining an
internal cavity having an outer portion in which the fluid rotates
when the separator is in use and an inner portion, the terminal insert
comprising a distinct member positioned within the longitudinally
extending body to impinge upon at least a portion of the fluid as it
rotates within the cavity to destructively interfere with the rotational
motion of the fluid within the cavity.
In accordance with the instant invention, there is also
provided a terminal insert for a cyclone separator for separating a
material from a fluid, the separator having a longitudinally extending
body and a wall, the wall having an inner surface and defining an
internal cavity in which the fluid rotates in a cyclonic pattern when
the separator is in use, the terminal insert comprising a member
having an outer wall spaced from the inner surface and configured to
impart changes in the rate of acceleration to at least a portion of the
fluid as it rotates within the cavity to reduce the rotational
momentum of the fluid to the point where the fluid has insufficient
momentum to maintain a cyclonic flow in the separator.
In accordance with the instant invention, there is also
provided a cyclone separator for separating a material from a fluid
comprising:
(a) a longitudinally extending body having a wall and
defining a longitudinal axis, the wall having an inner surface which
defines an internal cavity having an outer portion in which the fluid
rotates when the separator is in use and an inner portion; and,
(b) a terminal insert comprising a member having an
outer wall spaced from the inner surface and positioned to interact
with at least a portion of the fluid as it rotates in the outer portion of
the cavity to destructively interfere with the rotational motion of the
fluid within the cavity.
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In one embodiment the outer wall of the terminal insert
interacts with the portion of the fluid to impart to the portion of the
fluid a different speed, a different direction of travel or a different
velocity compared to that of the fluid rotating in the outer portion of
the cavity.
In another embodiment, at least a portion of the outer
wall is configured to continuously impart changes in the rate of
acceleration to the fluid as it rotates within the cavity.
In another embodiment, the terminal insert is centrally
positioned within the cavity and extends outwardly to impinge upon
the portion of the fluid.
In another embodiment, the outer wall of the terminal
insert is configured to create an area in the cavity wherein the fluid is
travelling at a velocity insufficient to maintain the rotational motion
of the fluid within the cavity. The area may have a receiving portion
for receiving the material which is separated from the fluid.
Alternately, the separator may be vertically disposed and the receiving
portion is positioned towards the lower end of the separator and
comprises a collecting chamber in which the separated material is
collected. Further, the separator may be vertically disposed and the
receiving portion is positioned towards the lower end of the separator
and is in flow communication with a collecting chamber in which the
separated material is collected.
In another embodiment, at least a portion of the inner
surface of the wall is defined by a continuous n-differentiable curve
swept 360 degrees around the axis wherein n >_ 2 and the second
derivative is not zero everywhere.
In another embodiment, at least a portion of the inner
surface of the wall is defined by a plurality of straight lines which
approximate a continuous n-differentiable curve swept 360 degrees
around the axis wherein n >_ 2 and the second derivative is not zero
everywhere.
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_7_
In another embodiment, the internal cavity has, in
transverse section, an inner portion in which the fluid rotates when
the separator is in use and at least one outer portion positioned
external to the inner portion and contiguous therewith, the outer
portion of the cavity extending outwardly from the inner portion of
the cavity and defining a zone in which at least a portion of the fluid
expands outwardly as it rotates in the plane defined by the transverse
section, the portion of the fluid in the outer portion of the cavity
having different fluid flow characteristics compared to those of the
fluid rotating in the inner portion of the cavity which promote the
separation of the material from the fluid.
In another embodiment, in transverse section, the wall
extends in a continuous closed path and has a non-baffled inner
surface which defines an internal cavity, the internal cavity having an
inner portion in which the fluid rotates when the separator is in use,
and at least one outer portion positioned external to the inner portion
and contiguous therewith defining a zone in which the wall is
configured to impart to at least a portion of the fluid as it rotates in the
plane defined by the transverse section different fluid flow
characteristics compared to those of the fluid rotating in the inner
portion of the cavity, which characteristics promote the separation of
the material from the fluid.
In another embodiment, the inner surface of the wall is
defined by, in transverse section, a continuous non-circular convex
closed path, the cavity having an inner portion positioned within the
non-circular convex closed path and at least one outer portion between
the inner portion and the non-circular convex closed path.
The separator may comprise a dirt filter for a vacuum
cleaner, an air inlet for turbo machinery, treatment apparatus
positioned upstream of a fluid pump, treatment apparatus positioned
upstream of a pump for a gas or treatment apparatus positioned
upstream of a pump for a liquid.
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_g_
By designing a cyclone separator according to the instant
invention, the parameters L/d and Lc/d may re constant or may vary
continuously and differentiably along the length of the cyclone axis
with substantial re-entrainment and, preferably without any re-
entrainment, of separated material. Thus, a cyclone may be designed
which will have a good separation efficiency over a wider range of
particle sizes than has heretofore been known. Accordingly, one
advantage of the present invention is that a smaller number of
cyclones may be employed in a particular application than have been
used in the past. It will be appreciated by those skilled in the art that
where, heretofore, two or more cyclones might have been required for
a particular application, that only one cyclone may be required.
Further, whereas in the past three to four cyclones may have been
required, by using the separator of the instant intention, only two
cyclones may be required. Thus, in one embodiment of the instant
invention, the cyclone separator may be designed for a vacuum
cleaner and may in fact comprise only a single cyclone as opposed to a
mufti-stage cyclone as is known in the art.
DESCRIPTION OF THE DRAWING FIGURES
These and other advantages of the instant invention will
be more fully and completely understood in accordance with the
following description of the preferred embodiments of the invention
in which:
Figure 1 is a cyclone separator as is known in the art;
Figure 1 is a cyclone separator as is known in the art;
Figure 2 is a perspective view of a cyclone separator
according to the instant invention;
Figure 3 is a cross-section of the cyclone separator of Figure
2 taken along the line 3-3;
Figures 4 - 11 are each alternate embodiments of the
cyclone separator of Figure 2;
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Figure 7;
invention;
Figure 12 is a cross sectional view along line 12 - 12 in
Figure 13 is a cyclone separator according to the instant
Figures 14(a), (b), (d), and (e) are each an alternate
embodiment of the terminal insert according to the instant invention;
and,
Figure 14(b).
Figures 14(c) is a cross sectional view along line 14 - 14 in
DESCRIPTION OF PREFERRED EMBODIMENT
As shown in Figures 2 - 10, cyclone separator 30 may
comprises a longitudinally extending body having a top end 32, a
bottom end 34, fluid inlet port 36, a fluid outlet port 38 and a separated
material outlet 40.
Cyclone separator 30 has a wall 44 having an inner surface
46 and defining a cavity 42 therein within which the fluid rotates.
Cyclone separator 30 has a longitudinally extending axis A-A which
extends centrally through separator 30. Axis A-A may extend in a
straight line as shown in Figure 2 or it may be curved or serpentine as
shown in Figure 11.
As shown in Figures 2, 4, 5, 7, 8, 9 and 10, cyclone separator
is vertically disposed with the fluid and material to be separated
entering cyclone separator 30 at a position adjacent top end 32. As
25 shown in Figure 6, cyclone separator 30 is again vertically disposed but
inverted compared to the position show in Figures 2, 4, 5, 7, 8, 9 and 10.
In this embodiment, fluid 48 enters cyclone separator 30 at a position
adjacent bottom end 34 of the separator. It will be appreciated by those
skilled in the art that provided the inlet velocity of fluid 48 is
30 sufficient, axis A-A may be in any particular plane or orientation, such
as being horizontally disposed or inclined at an angle.
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Fluid 48 may comprise any fluid that has material
contained therein that is capable of being removed in a cyclone
separator. Fluid 48 may be a gas or a liquid. If fluid 48 is a gas, then
fluid 48 may have solid particles and/or liquid particles and/or a
second gas contained therein such as by being suspended, mixed or
entrained therein. Alternately, if fluid 48 is a liquid, it may have solid
particles and/or a second liquid and/or a gas contained therein such as
by being suspended, mixed or entrained therein. It will thus be
appreciated that the cyclone separator of the instant invention has
numerous applications. For example, if fluid 48 is a gas and has solid
particles suspended therein, then the cyclone separator may be used as
the filter media in a vacuum cleaner. It may also be used as a scrubber
for a smoke stack so as to remove suspended particulate matter such as
fly ash therefrom. It may also be used as pollution control equipment,
such as for a car, or to remove particles from an inlet gas stream which
is fed to turbo machinery such as a turbine engine.
If fluid 48 is a gas and contains a liquid, then cyclone
separator 30 may be used as a mist separator.
If fluid 48 is a mixture of two or more liquids, then cyclone
separator 30 may be used for liquid/liquid separation. If fluid 48 is a
liquid and has a gas contained therein, then cyclone separator 30 may
be used for gas/liquid separation. If fluid 48 is a liquid which has solid
particles contained therein, then cyclone separator 30 may be used for
drinking water or waste water purification.
In the embodiment shown in Figure 2, wall 44, in
transverse section, is in the shape of an ellipse. In the embodiment
shown in Figure 4, wall 44 has a trumpet shape. Such shapes may be
prepared by sweeping a continuous n-differentiable curve 360° around
axis A-A wherein n is >_ 2 and the second derivative is not zero
everywhere. Preferably, n is >_ 2 and _< 1,000, more preferably n _< 100
and most preferably n <_ 10. If the second derivative is zero at a finite
number of points, then it may be zero from about 2 to 100 points,
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preferably from about 2 to about 30 points and, more preferably, at 2 to
points.
Fluid 48 enters cyclone separator through inlet port 36
and tangentially enters cavity 42. Due to the tangential entry of fluid 48
5 into cavity 42, fluid 48 is directed to flow in a cyclonic pattern in cavity
42 in the direction of arrows 50. Fluid 48 travels in the axial direction
in cavity 42 from fluid entry port 36 to a position adjacent bottom end
34. At one point, the fluid reverses direction and flows upwardly in
the direction of arrows 52 while material 54 becomes separated from
10 fluid 48 and falls downwardly in the direction of arrows 56. Treated
fluid 58, which has material 54 separated therefrom, exits cyclone
separator 30 via outlet port 38 at the top end 32 of cavity 42.
In the alternate embodiment shown in Figures 7 and 8,
cyclone separator 30 may be a unidirectional flow cyclone separator.
The cyclone separator operates in the same manner as described above
with respect to the cyclone separator 30 shown in Figure 2 except that
fluid 48 travels continuously longitudinally through cavity 42.
Material 54 becomes separated from fluid 48 and travels downwardly
in the direction of arrows 56. Treated fluid 64, which has material 54
separated therefrom, continues to travel downwardly and exits cyclone
separator 30 via outlet port 38 at a position below bottom end 34 of
cavity 42.
As exemplified in the Figures 2 - 10, cyclone separator may
have a variety of shapes. In particular, cyclone separator may have an
outer rotational wall 44 which is of any shape known in the industry.
For example, outer wall 44 may be either cylindrical (see for example
Figures 12(a) - (h)) or frusto-conical in shape.
In one embodiment, cavity 42 has an inner portion in
which fluid rotates as it travel longitudinally in cyclone separator 30
and an outer portion exterior thereto but contiguous therewith. The
outer portion of cavity 42 may extend outwardly from the inner
portion of the cavity to define a zone in which at least a portion of
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fluid 48 expands outwardly as it rotates in a plane defined by the
transverse section whereby the portion of the fluid in the outer
portion of cavity 42 has different fluid flow characteristics compared to
those of fluid 48 rotating in the inner portion of cavity 42 which
promote the separation of the material from the fluid. In such a
configuration wall 44 of cavity 42 may promote the formation of one
or more second cyclones exterior to inner portion 42.
Alternately, outer wall 44 of cavity 42 may be in the shape
of a continuous n-differentiable curve wherein n is >_ 2 and the second
differential is not zero everywhere, swept 360° around the
longitudinal axis of cavity 42 (see for example Figures 22(a) - (h)).
As shown in Figures 5, 8 and 10, fluid 48 may enter cavity
42 axially. In such a case, fluid entry port 36 is provided, for example,
at top end 32 of cyclone separator 30. A plurality of vanes 60 are
provided to cause fluid 48 to flow or commence rotation within cavity
42. It would be appreciated by those skilled in the art that fluid 48 may
enter cavity 48 from any particular angle provided that fluid entry port
36 directs fluid 48 to commence rotating within cavity 42 so as to assist
in initiating or to fully initiate, the cyclonic/swirling motion of fluid
48 within cavity 42.
Referring to Figure 6, cyclone separator 30 is vertically
disposed with fluid entry port 36 positioned adjacent bottom end 34.
As fluid 48 enters cavity 42, it rises upwardly and is subjected to a
continuously varying acceleration along inner surface 46 of cavity 42.
Gravity will tend to maintain the contained material (if it is heavier)
in the acceleration region longer thereby enhancing the collection
efficiency. At some point, the air reverses direction and flows
downwardly in the direction of arrow 64 through exit port 38. Particles
54 become separated and fall downwardly to bottom end 34 of cyclone
separator 30. If bottom end 34 is a contiguous surface, then the
particles will accumulate in the bottom of cyclone separator 30.
Alternately, opening 40 may be provided in the bottom surface of
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cyclone separator 30 so as to permit particles 54 to exit cyclone separator
30.
It will also be appreciated that cyclone separator 30 may
have a portion thereof which is designed to accumulate separated
material (for example, if the bottom surface of the cyclone separator
Figure 6 were sealed) or, if the bottom of cyclone separator 30 of Figure
5 had a collection chamber 62 (which is shown in dotted outline)
extend downwardly from outlet 40. Alternately, outlet 40 may be in
fluid communication with a collection chamber 62. For example, as
shown in Figure 4, collection chamber 62 is positioned at the bottom of
and surrounds outlet 40 so as to be in fluid communication with
cyclone separator 30. Collection chamber 62 may be of any particular
configuration to store separated material (see Figures 7 and 8) and/or
to provide a passage by which separated material 54 is transported
from cyclone separator downstream (see Figure 4) provided it does not
interfere with the rotational flow of fluid 48 in cavity 42.
An insert 70 may be positioned within cavity 42. In such a
case, insert 70 may have an upstream end 72, a downstream end 74 and
a wall 76 extending between upstream end 72 and downstream end 74.
Wall 76 has an outer surface 78. In one embodiment, insert 70 may be
hollow and have an inner cavity 80. This particular configuration is
advantageous if cyclone separator 30 is a reverse flow separator as
shown in Figure 2 whereby fluid 48, after material 54 has been
separated therefrom, travels upwardly through cavity 80 of insert 70 to
fluid outlet port 38. It will be appreciated that if cyclone separator 30 is
a unidirectional flow separator as shown in Figures 7 and 8, that insert
70 may be a closed or a solid member.
Insert 70 is a distinct member positioned within cavity 42
to imping upon at least a portion fluid 48 as it rotates within cavity 42
thereby changing the speed, the direction of travel or the velocity of
the fluid and causing some of the material contained in fluid 48 to be
separated from fluid 48. It will be appreciated that insert 70 does not
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imping upon fluid 48 to a degree whereby the cyclonic motion of fluid
48 in cavity 42 is prevented. Instead, insert 70 impinges to a sufficient
degree to cause at least some of the contained material to be separated
from fluid 48 while still permitting fluid 48 to maintain sufficient
momentum to continue its rotational motion within cavity 42.
When fluid 48 rotates in a cyclonic pattern within cavity
42, it will rotate only in the outer portion of cavity 42. The inner
portion of cavity 42 will comprise a low pressure area where fluid 48 is
stagnant or, in the case of a reverse flow cyclone, fluid 48 is travelling
upwardly through the dead air space in the centre of cavity 42. Insert 70
may be mounted (e.g. from above or from below cyclone separator 30)
within this inner portion and extend radially outwardly from the
inner portion so as to interact with at least a portion of fluid 48 as it
rotates in the outer portion of cavity 42 to impart to the portion of the
fluid with which it interacts different fluid flow characteristics
compared to those of fluid 48 rotating in the outer portion of cavity 42
which promote the separation of the material from the fluid. For
example, insert 70 may interact with fluid 48 to impart to at least a
portion of fluid 48 a different speed, a different direction of travel or a
different velocity compared to that of fluid 48 rotating in the outer
portion of cavity 42.
Preferably, outer wall 76 of inset 70 is spaced from inner
surface 46 and is configured to impart changes, and more preferably to
impart continuous changes, in the rate of acceleration to at least a
portion of fluid 48 as it rotates within cavity 42 causing some of the
material to be separated from fluid 48.
In order to allow cyclone separator 30 to achieve a good
separation efficiency over a wider range of small particle sizes, wall 76
is configured to impart changes in one or more of the speed, direction
of travel, velocity and the rate of acceleration of fluid 48 as it rotates
within cavity 42. By allowing fluid 48 to be subjected to such varying
fluid flow characteristics, different size particles may be separated from
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fluid 48 at different portions along the path of travel of fluid 48 in
cavity 42.
In one embodiment, insert 70 may be configured to impart
changes to the rate of acceleration of fluid 48 as it travels
longitudinally through cavity 42. Alternately, or in addition, insert 70
may be configured to impart changes in the rate of acceleration of fluid
48 as it travels transversely around wall 44.
For example, if _ the rate of acceleration continually
increases along the length of cyclone separator 30, as would be the case
of Figure 4, continuously finer particles would be separated as the fluid
proceeds from the top end 32 to bottom end 34. A boundary or prendtl
layer which exists along inner surface 46 of wall 44 and outer surface 78
of wall 76 provides low flow or low velocity zones within which the
separated material may settle and not become re-entrained by the faster
moving air rotating within cavity 42. As fluid 48 travels downwardly
through the cyclone separator shown in Figure 4, the contained
material, which for example may have a higher density then that of
the fluid, would be subjected to continuously increasing acceleration
and would be separated from the fluid and travel downwardly along
inner surface 46 of wall 44 and outer surface 78 of wall 76 in the
boundary or prendtl layer. As the fluid travels further downwardly
through cyclone separator 30, the fluid would be accelerated still more.
Thus, at an intermediate level of cyclone separator 30 of Figure 4, fluid
48 would be travelling at an even greater rate of speed compared to the
top end 32 resulting in even finer contained material becoming
separated. This effect would continue as fluid 48 rotates around inner
surface 46 to bottom end 34.
In another embodiment, the acceleration may continually
decrease throughout the length of cyclone separator 30. In another
embodiment, the acceleration may vary between continuously
increasing and continuously decreasing along the length of cyclone
separator 30.
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In the embodiment shown in Figure 2, fluid 48 is
subjected to changes in its rate of acceleration as it travels transversely
around wall 44. As shown in Figure 2, cavity 42 and insert 70 are
elliptical in transverse section and have a major axis a-a and a minor
axis b-b. The portion of maximum curvature of inner surface 46 and
outer surface 78 in the transverse plane is denoted by CLr,aX and the
portion of minimum curvature of inner surface 46 and outer surface
78 in the transverse plane is denoted by Cmin. By allowing fluid 48 to be
subjected to varying acceleration as it rotates in the transverse plane,
different size particles may be separated from fluid 48 at different
portions along the circumference of cyclone separator 30. For example,
the acceleration of fluid 48 would increase along sector C,nax of cyclone
separator 30 and particles having a different density would be
separated at this portion of the circumference. Similarly, for example,
the acceleration of fluid 48 would decrease along sector Cmin of cyclone
separator 30 and particles having a different density would be
separated at this portion of the circumference. A boundary or prandtl
layer which exists along inner surface 46 of wall 44 and outer surface 78
of wall 76 provides a low flow or a low velocity zone within which the
separated material may settle and not become re-entrained by the faster
moving air rotating within cavity 42.
Increasing the diameter of insert 70 decelerates the fluid.
The contained material, which has a different density to the fluid
would therefore change velocity at a different rate then the fluid. For
example, if the contained material comprised particles which had a
higher density, they would decelerate at a slower rate then fluid 48 and
would therefore become separated from fluid 48. As the space between
inner surface 46 and outer surface 78 widens, fluid 48 would accelerate.
Once again, the denser particles would be slower to change speed and
would be travelling at a slower rate of speed than fluid 48 as fluid 48
enters the wider portion of cavity 42 thus again separating the solid
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particles from fluid 48. It would be appreciated that if the particles
where less dense then fluid 48, they would also be separated by this
configuration of insert 70.
If fluid 48 comprises a mixture of two fluids which are to
be separated, it is particularly advantageous to include in insert 70 at
least one portion which is configured to decrease the rate of
acceleration of fluid 48 as it passes through that portion of the
separator. In this configuration, the less dense fluid would decrease its
velocity to follow the contours of outer surface 78 more rapidly then
the denser fluid (which would have a higher density), thus assisting in
separating the less dense fluid from the more dense fluid.
In one embodiment, at least a portion of inner surface 46
and a portion of outer surface 78 are the same and, more preferably,
inner surface 46 and outer surface 78 are of a similar shape, but spaced
apart, for the entire length of insert 70 (see Figures 2 - 6). Preferably,
any point on outer surface 78 is at least 0.1 inches from inner surface 46
and, most preferably, inner surface 46 and outer surface 78 are spaced at
least 0.125 inches apart.
Insert 70 may be of several different configuration and
may be configured to promote the formation of one or more second
cyclones interior of the rotation of the fluid in cavity 42.
In accordance to the instant invention, a cyclone separator
is provided with a terminal insert 100. Terminal insert 100 has an
upstream end 102 a downstream end 104 and an outer surface 106.
25 Terminal insert comprises a member positioned within cavity 42 to
imping upon at least a portion of fluid 48 as it rotates within cavity 48
to destructively interfere with the rotational motion of fluid 48 within
cavity 42. Preferably, terminal insert 100 impinges to a sufficient degree
whereby fluid 48 has insufficient momentum to maintain a cyclonic
30 flow in cavity 42. As shown in Figure 13, insert 100 may be centrally
positioned along the longitudinal axis A-A of cavity 42 and extend
outwardly to imping upon at least a portion of fluid 48 as it rotates in
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cavity 42. As the diameter of terminal insert 100 increases, it will
increasingly imping upon fluid 48 and result in a change in the
rotational velocity of fluid 48 in cavity 42. If the rotational velocity is
decreases to a sufficient point, then the cyclonic flow of fluid 48 in
cavity 42 will be terminated.
It will be appreciated that terminal insert may have a
variety of configurations. For example, as shown in Figures 13 and
14(a), insert 100 may be a generally trumpet shaped member.
Alternately, as shown in Figures 14(b) and (c) insert 100 may be a
generally trumpet shaped member which has a plurality of
longitudinally extending vanes 108 provided thereon. Vanes 108
extend outwardly into fluid 48 as it rotates in cavity 42 thereby
disrupting the cyclonic flow of fluid 48 therein.
As shown in Figure 14(d), insert 100 may comprise a
plurality of longitudinally extending members (such as rods), which
extend upwardly into cavity 48. The rods may be secured to the bottom
surface of cyclone separator 30. Alternately, the rods may be affixed in a
position exterior to cavity 42 and extend into cavity 42 so as to interact
with fluid 48 to disrupt its rotational motion. It will be appreciated that
the rods may be positioned symmetrically around longitudinal axis A
A. Alternately, they may be positioned non-symmetrically there
around. It will also be appreciated that rods may be a variety of shapes
such as, in transverse section, squares, ellipses or other closed convex
or abode shapes. Further, the transverse section of terminal insert 100
may vary longitudinally.
As shown in Figure 14(e), insert 100 may comprise a
member that is longitudinally positioned within cavity 42 and has a
plurality of arms 110 which extend outwardly therefrom and
preferably radially outwardly therefrom. Each of the arms 100 may
have the same transverse length and cross sectional profile.
Alternately, as shown in Figure 14(e) arms 110 may have a transverse
length that increases towards bottom end 34 of cavity 42 so as to create
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a discontinuous profile similar to that of insert 100 shown in Figure
14(a).
In a further alternate embodiment, as shown in Figures 7
and 12, terminal insert 100 may have a helical member 112 extending
there around.
It is particulary preferred to incorporate a terminal insert
100 in a unidirectional flow cyclone as shown in Figures 7 and 12. In
this figures, terminal insert 100 is provided as a longitudinally
continuation of insert 70. It will be appreciated that terminal insert 100
need not be connected to insert 70 but may be separately mounted
therein or, in fact, cyclone separator may not have an insert 70.
According to this embodiment, fluid 48 travels downstream through
cavity 42 from top end 32 to bottom end 34. Separated material 54
travels downwardly into collecting chambers 62 as shown by arrows 56.
As fluid 48 rotates around cavity 42, the radially inner portion thereof
encounters outer wall 106 of terminal insert 100 which decreases the
rotational velocity of fluid 48 thereby reducing and, preferably,
terminating the cyclonic flow of fluid 48 in the lower portion of cavity
42.
This has two advantages. First, by reducing or terminating
the cyclonic flow of fluid 48 in the lower portion of cavity 42, fluid 48 is
easier to direct into fluid outlet port 38. Further, when the cyclonic
flow of fluid 48 in cavity 42 is terminated, fluid 48 commences to
travel at a relatively slow speed in cavity 42 thereby preventing the re-
entrainment of separated material 54. It will be appreciated that instead
of having a sealed collecting chamber as shown in Figure 7, collecting
chamber may have a distal end 114 which defines an open passage
which extends to convey separated material 54 away from cavity 42.
In the longitudinal direction defined by axis A-A, inner
surface 46 is preferably continuous. By this term, it is meant that,
while inner surface 46 may change direction longitudinally, it does so
gradually so as not to interrupt the rotational movement of fluid 48
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within cavity 42. It will be appreciated that, in the longitudinal and/or
the transverse direction, that iruler surface 46 of cavity 42 and/or outer
surface 78 of wall 76 may be defined by a plurality of straight line
portions, each of which extends for a finite length. Inner surface 46
may be defined by 3 or more such segments, preferably 5 or more such
segments and most preferably, 10 or more such segments.
It will also be appreciated that, depending upon the degree
of material which is required and the composition of the material in
the fluid to be treated that a plurality of cyclone separators each of
which, or only some of which, may be connected in series. The
plurality of separators may be positioned side by side or nested (one
inside the other) as is shown in Figure 10.
