Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
DUAL CYCLONE SEPARATOR
FIELD OF THE INVENTION
The present invention relates to a dual cyclone separator.
BACKGROUND OF THE INVENTION
Cyclonic separator systems are commonly used to segregate immiscible phases of
a
process stream, such as when a process stream comprises a mixed liquid phase
and
gas phase. Separator systems are commonly used to separate immiscible
entrained
liquids from a gas phase of a mixed gas/liquid process stream, wherein the
process
stream enters cyclonic chambers through inlets that are tangential to the
curvature of
each of the cyclonic chambers. As a result of the velocity and the tangential
angle at
which the liquid/gas process stream enters the cyclonic chamber, centrifugal
forces act
on the process stream and cause it to spin around the curvature of the
cyclonic chamber.
Centrifugal forces acting on each of the immiscible phases in the process
stream, cause
the phases to move either away from or towards the centre of the cyclonic
chamber. A
difference in the mass and densities of phases of the process stream cause the
heavier
phases to coalesce on the inner wall of the cyclonic chamber and travel in a
downwards
direction through the cyclonic chamber due to the force of gravity, while the
lighter, or
gaseous, phase(s) of the gas phase tend to remain closer to the centre of the
cyclonic
chamber forming a central upward moving column of lighter phase that exit
through an
aperture positioned in the upper covering of the cyclonic chamber.
To ensure effective light/heavy phase separation, the incoming process stream
needs
to flow at high velocity to create a greater centrifugal force for separation
of the heavier
phase from the lighter phase. As well, the gas outlet aperture must be
designed to a
minimum size based on how much lighter phase is being separated out. There are
further limits to the design of the tangential inlets to each of the cyclonic
chambers to
create the desired high momentum and flow rate of the incoming process fluid.
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An example of a prior art, single cyclonic separator can be seen in US
3,481,118. An
example of a prior art multicyclonic separator can be seen in US 3,793,812.
Since the sizing of cyclonic chambers is a precise science, height and
diameter
dimensions are limited based on the stream to be separated, velocity and
volume
available. Typically, when using multiple separators, these specific size
requirements
lead to a height and diameter that is often too narrow and tall to withstand
the high
vibration commonly experienced in the separation environment. On example of
such
high vibration environment is when cyclone separators are used with
reciprocating
compressor scrubbers.
Separator dimensions can also limit the size of the lower area of the cyclonic
separator,
called a sump, which is used to collect liquids that are separated out of the
entrained
gas-liquid stream fed to the separator. Limitations to sump size lead to less
than
desirable residence time to separate out any entrained gases that may be
trapped in the
falling liquid.
As well, the external body of cyclonic separators must meet strict pressure
vessel and
welding requirements to ensure a level of integrity due to the high internal
pressure,
vibrations and velocities used in cyclonic separation. Involute or tangential
inlets
commonly used on cyclonic separators connect with the separator body in such a
way
that can prove difficult to meet the reinforcement requirements that are
needed for the
design of a pressure vessel.
As such, there is a need for an improved design of a cyclonic separator for
separation of
a liquid phase from a gas phase in a mixed process stream.
SUMMARY
The present disclosure thus provides a cyclonic separator for separation of a
mixed liquid
phase/gas phase process stream. The cyclonic separator comprises an outer
shell, at
least two cyclonic chambers located within the outer shell, each cyclonic
chamber having
an upper end and a lower end; a single, common tangential inlet passing
tangentially
through the outer shell and into each of the at least two cyclonic chambers,
proximal the
upper ends thereof; a gas outlet tube located at least partially within each
cyclonic
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chamber, extending axially from a lower gas outlet end within each cyclonic
chamber
and below the tangential inlet, to an upper gas outlet end extending out of
each of the
upper end of the at least two cyclonic chambers, said upper gas outlet ends
being in
fluid communication with a common gas chamber located above the outer shell;
and a
circumferential recycle opening formed around and through a thickness each gas
outlet
tube, in a portion of each gas outlet tube located axially between the upper
end of
cyclonic chambers and the common gas chamber, said recycle opening thus being
in
fluid communication with an inside cavity of the outer shell.
It is to be understood that other aspects of the present invention will become
readily
apparent to those skilled in the art from the following detailed description,
wherein various
embodiments of the invention are shown and described by way of illustration.
As will be
realized, the invention is capable for other and different embodiments and its
several details
are capable of modification in various other respects, all without departing
from the spirit
and scope of the present invention. Accordingly the drawings and detailed
description are
to be regarded as illustrative in nature and not as restrictive.
BRIEF DESCRIPTION OF THE DRAWINGS
A further, detailed, description of the invention, briefly described above,
will follow by
reference to the following drawings of specific embodiments of the invention.
The drawings
depict only typical embodiments of the invention and are therefore not to be
considered
limiting of its scope. In the drawings:
Figure 1 is a perspective view of one embodiment of the separator system of
the present
invention;
Figure 2 is a top plan view of one embodiment of the separator system of the
present
invention;
Figure 3 is a front cross sectional view of one embodiment of the separator
system of the
present invention;
Figure 4 is a perspective view of the cyclonic chambers of the present
invention; and
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Figure 5 is a detailed view of the tangential inlet of one embodiment of the
present
invention.
The drawings are not necessarily to scale and in some instances proportions
may have
been exaggerated in order more clearly to depict certain features.
DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS
The description that follows and the embodiments described therein are
provided by
way of illustration of an example, or examples, of particular embodiments of
the
principles of various aspects of the present invention. These examples are
provided for
the purposes of explanation, and not of limitation, of those principles and of
the
invention in its various aspects.
With reference to the figures, the present invention provides a dual cyclonic
separator
system 2 having a common tangential inlet. The present separator system 2
combines
two cyclonic separators or cyclonic chambers 4a, 4b in parallel, having a
single
common involute/tangential inlet 8. The pair of cyclonic chambers 4a, 4b are
placed
within an outer shell 6. The shell 6 preferably takes the shape of a
vertically oriented
cylinder, although it would be possible for the shell to take on other shapes
such as a
vertically oriented rectangular prism, without departing from the scope of the
present
invention.
The individual separators 4a, 4b are still sized in accordance with sizing
specifications
based on properties of the streams to be separated, including but not limited
to relative
densities and phases, inlet velocity, inlet pressure. However, by housing the
pair of
cyclonic chambers 4a, 4b within a shell 6,the dimensions of the shell 6 can be
varied to
provide stability and vibration resistance as required by the environmental
conditions.
Thus, by placing the cyclonic chambers 4a, 4b within a shell 6, there is more
sizing
flexibility.
The tangential inlet 8 is hollow and passes through the shell 6 and into fluid
communication with an upper end 4ai and 4bi, each of cyclonic chambers 4a, 4b.
The
inlet 8 preferably has a circular cross sectional geometry, although a square
or
rectangular cross section geometry is also possible and within the scope of
the present
invention. While the figures illustrate the tangential inlet 8 as being at a
right angle 8a to
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a length of the shell 6 and to a length of the cyclonic chambers 4a, 4b, it is
also possible
for the tangential inlet 8 to slope downwards at an angle greater than 90
degrees to the
length of either the shell 6, or the cyclonic chambers 4a, 4b, or both, thus
enhancing the
gravity pull on the heavier liquid phase of the mixed process stream as it
enters the
separators 4a, 4b.
The process stream enters the separator system 2 via tangential inlet and
generally
divides into portions that enter each of the separators 4a, 4b. In a more
preferred
embodiment, a divider 20 may be inserted or other means may be used to divide
the
process stream into each of the cyclonic chambers 4a, 4b.
The present tangential inlet 8 connects externally with the outer shell 6 of
the system 2,
the geometry of the connection can be seen in Figure 1, which is either curved
circle, in
the case of circular cross section inlet 8, or a curved rectangle or curved
square, in the
case of alternate inlet cross sectional geometries. These relatively simple
angles and
geometries of connection between the tangential inlet 8 and the shell 6 means
that
welding the inlet 8 to the shell 6 can be done simply without requiring
special skill or
tools. At the same time the weld can be made securely to meeting safety
regulations
and welding strength requirements need on external surfaces to which workers
are
exposed.
By contrast, internal to the shell 6, the tangential inlet 8 connects with
each of the
cyclonic chambers 4a, 4b at a relatively more complex angle and geometry as
seen in
Figure 4, which would be much more difficult to weld to external safety
regulations and
weld strength ratings requirements. However, since the connection of
tangential inlet
8 to the cyclonic separator pair 4a, 4b is internal; the welding of these
components
can be done without the necessity to meet strict external fabrication and
welding
requirements.
In operation, a process stream comprised of one or more immiscible gases
entrained
in one or more liquids enters each of the cyclonic chambers 4a, 4b through the
common
tangential inlet 8, with the total volume of the process stream substantially
equally
distributed between each separation column of each cyclonic chambers 4a, 4b.
In a
preferred embodiment, the substantially equal distribution of the total volume
of the
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process stream towards each of the cyclonic chambers 4A, 4B.may be facilitated
by the
divider 20,
An inner surface 11 of each of the cyclonic chambers 4a, 4b, provides a
surface
against which the process stream is manipulated to move in a helical or
cyclonic motion.
The cyclonic movement caused by the tangential inlet 8 combined with the inner
surface
11 results in heavier, or liquid, phases of the process stream to be forced
radially
outwardly by centrifugal force towards and against the inner surface 11. The
vertical
orientation of the cyclonic chambers 4a/4b allows the force of gravity to act
on the
heavier phase, pulling it in a helically downwards path along and down the
inner surface
11 to the lower end 4aii/4bii of the cyclonic chambers 4a/4b. Preferably, a
recycle plate
18 sits in the lower end 4aii/4bii of the cyclonic chambers 4A, 4B, comprising
a central
opening 18a, and defining an annular opening 18b between the inner surface 11
and an
edge of the recycle plate 18. The recycle plate 18 serves to stabilize the
heavier phase
as it exits the cyclonic chambers 4a/4b through annular opening 18b. The
recycle plate
18 also serves as part of a recycle system to be described in further detail
below.
With heavier fluids pushed radially outwardly by centrifugal forces towards
the inner
surface 11 of each cyclonic chamber 4a/4b, the lighter, or gaseous, phases of
the
process stream, due to their lower masses and densities, tend to collect
substantially in
a central core of the cyclonic chambers 4a, 4b forming a central, upward
moving column
of lighter, or gaseous, phases that enter gas outlet tubes10a, 10b that are
located
partially within each cyclonic chamber 4a, 4b.
The gas outlet tubes 10a, 10b extend axially from a lower gas outlet end
located below
tangential inlet 8, to an upper gas outlet end extending out of the cyclonic
chambers
4a/4b, the upper gas outlet ends being in fluid communication with a common
gas
chamber 22 formed of an upper end of the shell 6.
In a preferred embodiment, one or more liquid creep preventers 16a, 16b may be
connected around an outside of the lower gas outlet ends of gas outlet tubes
10a, 10b to
ensure that no liquid is misdirected or otherwise allowed to creep upwards and
into the
gas stream and travel upwards through the gas outlet tubes 10a, 10b. The
liquid creep
preventers 16a, 16b may take any number of forms, it would be well understood
by a
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person of skill in the art that any modification or addition to a lower end of
the gas outlet
tubes 10a, 10b that would serve to deflect liquid from the gas outlet tubes
10, 10b would
be encompassed by the scope of the present disclosure.
Preferably, while each cyclonic chamber 4a, 4b is independent, the cyclonic
chambers
4a, 4b share a common tangential inlet 6 and also a common liquid sump 14. In
a further
preferred embodiment of the present disclosure, a common lower area of the
outer shell 6
forms the common sump 14, thereby replacing individual sumps for each single
cyclonic
chamber 4a, 4b. The common sump 14 collects liquids that flow helically
downwardly
along the inner surfaces 11 of the cyclonic chambers 4a, 4b, out the lower
ends 4aii and
4bii of each cyclonic chamber 4a/4b, vial annular openings 18b. The present
sump 14
provides a greater volume than the combined volumes of two single separator
sumps.
The increased volume allows for increased residence time for separation any
entrained
gases that may be trapped in the falling liquid. This improves separation
efficiency and
gas recovery. Any released gases from the sump 14 travel upwardly through the
central
opening 18a in recycle plate 18 and then up through gas outlet tubes 10a, 10b,
to the gas
chamber 22 and out gas outlet 30.
To reduce the occurrence of entrained liquids in the upwardly travelling
separated gas
stream, many prior art separator systems make use of an external recycle arm
in fluid
communication with the gas outlets and extending downwardly to the separator
sump.
Such external recycle arms require welding to an outer surface of the
separator and can
affect the integrity of the separator system. In the present invention no such
external
recycle arm is required. Instead, a circumferential recycle opening 24 is
formed around
and through a thickness of each gas outlet tube 10a/10b in a portion of each
of the gas
outlet tubes 10a, 10b that extends above the upper ends 4ai, 4bi of cyclonic
chambers
4a, 4b, but remains below the common gas chamber 22. In this way the recycle
opening 24 is within fluid communication of an inside cavity 26 of the outer
shell 6. The
opening 24 allows for any entrained liquid in the upwards moving gas stream in
the gas
outlet tubes 10a/10b to exit the gas outlet tubes 10a, 10b and enter the
inside cavity 26
of the outer shell 6. The inside cavity 26 of the outer shell 6 acts as a
recycle area,
allowing the exiting liquid to fall through the inside 26 of the shell 6 and
down to the
sump 14.
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Should there be any lighter, or gaseous phase trapped in the exiting liquid
travelling
down the inside cavity 26 of the shell 6, this is pulled into central opening
18a of the
recycle system 18 along with any released gases from the sump 14. These then
travel
upwardly through the central core of the cyclone chambers 4a/4b and into the
lower gas
outlet ends of gas outlet tubes 10a, 10b.
In a preferred embodiment, the recycle opening 24 is formed by supporting a
gas outlet
tube collar 12a, 12b over each gas outlet tubes 10a, 10b by means of one or
more
support brackets 28, providing a gap between the gas outlet tube collar 12a,
12b and the
gas outlet tubes 10a, 10b, said gap defining the recycle opening 24 to allow
exit of
entrained liquid from the gas outlet tubes 10a, 10b out to the inner cavity 26
of the shell
6.
The pairing of the cyclonic chambers 4a, 4b within the outer shell 6 allows
for the shell 6
to be designed shorter, stubbier, and therefore more stable than a single
tall, narrow
separator that is sensitive to vibration. Since the sizing of cyclonic
chambers is a
precise science, height and diameter dimensions are limited based on the
stream to be
separated, velocity and volume available. The present design allows cyclonic
chambers
4a, 4b to be designed to meet process requirements, while the outer shell 6 is
designed
with stability in mind, thereby achieving both goals.
The outer shell 6 is preferably cylindrical in geometry. It is generally
easier and less
expensive to manufacture, and is just as efficient or more efficient at
separating an inlet
stream comprised of immiscible gas and liquid phase than other, more complex
and
expensive geometries for an cyclonic separators, such as a conical or a frusto-
conical
geometry.
The previous description of the disclosed embodiments is provided to enable
any
person skilled in the art to make or use the present invention. Various
modifications to
those embodiments will be readily apparent to those skilled in the art, and
the generic
principles defined herein may be applied to other embodiments without
departing from
the spirit or scope of the invention. Thus, the present invention is not
intended to be
limited to the embodiments shown herein, but is to be accorded the full scope
consistent with the claims, wherein reference to an element in the singular,
such as by
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use of the article "a" or "an" is not intended to mean "one and only one"
unless
specifically so stated, but rather "one or more". All structural and
functional equivalents
to the elements of the various embodiments described throughout the disclosure
that are
known to those of ordinary skill in the art are intended to be encompassed by
the
elements of the claims. Moreover, nothing disclosed herein is intended to be
dedicated
to the public regardless of whether such disclosure is explicitly recited in
the claims. No
claim element is to be construed under the provisions of 35 USC 112, sixth
paragraph,
unless the element is expressly recited using the phrase "means for" or "step
for".
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