Note: Descriptions are shown in the official language in which they were submitted.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
METHODS FOR CENTRIFUGALLY SEPARATING
MIXED COMPONENTS OF A FLUID STREAM
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to methods for centrifugally separating
components of fluids having different density.
2. The Relevant Technology
Water purification is an age-old activity that has been pursued to achieve
both
potable water and water for industrial use. With the rise of
industrialization, water
to purification took on a new importance because industrial water usage
generally
involved discharging contaminated water into the environment. As concerns
about
the environment have increased, water discharged into the environment has been
subjected to increasingly higher standards. Thus, increased efforts have been
undertaken to identify methods of processing water to substantially reduce
both
dissolved and particulate pollutants.
One aspect of water purification that is particularly time consuming and/or
equipment intensive is liquid-solid separation. Traditionally, settling ponds,
or
thickeners, have been used in which a large volume of particulate-containing
water is
allowed to reside in a quiescent state. With the force of gravity acting on
the mixture,
the particulate, even those in the Stokes flow regime, will separate from the
liquid.
One disadvantage to the use of thickeners is that they have to be extremely
large to have any significant flow capacity. Thus, their use is not practical
in crowded
urban areas where the need for such water purification systems is often the
greatest.
Consequently, thickeners have been developed that allow for a continuous flow
of
particulate-containing liquid into the center of the thickener, producing a
clarified
supernatant liquid and a compacted sludge. The compacted sludge, exiting from
the
bottom of the thickener, typically has a water content that amounts to between
10 and
percent of total water being fed to the thickener.
Traditional thickeners have been improved in the last decade or so with the
30 advent of the high-rate thickener. The high-rate thickener has a center
feed well that
extends below the mud line of the underflow material. Accordingly, all water
entering the thickener must pass through the sludge which acts as a filter
medium. By
using the sludge as a filter, solid-liquid separation rates are increased,
albeit only
incrementally over that of traditional thickeners. Additionally, high-rate
thickeners
CA 02474297 2011-10-21
2
also must be very large and, consequently, also have large footprints,
rendering their use
impractical in many situations.
Another aspect of separation includes liquid-liquid systems such as separating
the
oil and water from a sump in a machine shop or in a washing bay for trains or
buses etc.
Other liquid-liquid separation systems are utilized in the food industry where
oil and water
need separation. One of the problems in the prior art is the effect of load
disturbances such
as a surge of oil or water in a cleaning operation that upsets the balance of
the oil/water
feed ratio to the separator. Although the separator may be controlled to
prevent one
component from entering the wrong exit stream, a catastrophic surge of one
component or
the other cannot be controlled.
In one aspect of the invention, a method for separating particulate matter
from a
fluid in which the particulate matter is suspended is described. A fluid
containing a
particulate matter is fed into a chamber of a vessel through an inlet, the
chamber being at
least partially bounded by a peripheral wall and the chamber also
communicating with an
outlet. The vessel is rotated about a rotational axis extending through the
vessel such that
at least a portion of the particulate matter settles out of the fluid and
against at least a
portion of the peripheral wall of the vessel. A stream of removal fluid is
delivered into the
rotating vessel at or adjacent to the peripheral wall such that delivery of
the removal fluid
into the vessel causes at least a portion of particulate matter settled
against the peripheral
wall to resuspend within the fluid. At least a portion of the fluid having the
resuspended
particulate matter therein is extracted from the vessel through an extraction
tube, the
extraction tube having an opening to receive the fluid at or adjacent to the
peripheral wall.
At least a portion the fluid from which the particulate matter has settled out
is removed
through the outlet of the vessel. The vessel is rotated concurrently with a
shaft assembly
that extends through and is coupled with the vessel, the shaft assembly
rotating about the
rotational axis. The stream of removal fluid is fed to the chamber through a
delivery
channel bounded by the shaft assembly. The fluid containing the particulate
material is
fed to the chamber along an inlet channel bounded by the shaft assembly, the
delivery
channel and the inlet channel each having a central longitudinal axis that
extends along the
rotational axis.
In another aspect of the invention, a separator is described. The separator
includes
a vessel having a peripheral wall bounding a chamber, the vessel being
rotatable about a
rotational axis extending through the vessel, the chamber communicating with
an inlet and
a first outlet. A plurality of fins are disposed within the chamber. A first
tube extends
from toward the rotational axis to toward the peripheral wall, the first tube
being coupled
CA 02474297 2011-10-21
2a
with a fluid source for selectively dispending a fluid stream at or adjacent
to the peripheral
wall. A second tube extends from toward the rotational axis to toward the
peripheral wall,
the second tube having a first end in fluid communication with the exterior of
the vessel
and an opposing second end bounding a second outlet, the first outlet being
disposed
closer to the rotational axis than the second outlet such that during use a
fluid boundary
line can be formed between the first outlet and the second outlet. A shaft
assembly
extends through and is coupled with the vessel, the shaft assembly being
rotatable
concurrently with the vessel about the rotational axis. A delivery channel is
bounded by
the shaft assembly and communicates with the first tube. An inlet channel is
bounded by
the shaft assembly and communicates with the chamber, the delivery channel and
the inlet
channel each having a central longitudinal axis that extends along rotational
axis.
BRIEF DESCRIPTION OF THE DRAWINGS
Various embodiments of the present invention will now be discussed with
reference to the appended drawings. It is appreciated that these drawings
depict only
typical embodiments of the invention and are therefore not to be considered
limiting of its
scope.
Figure 1 is a block diagram overview of a process that uses one or more of the
separators of the present invention;
Figure 2 is a perspective view of one embodiment of a solid-liquid separator
of the
present invention;
Figure 3 is a cross-sectional view of one embodiment of the solid-liquid
separator
shown in Figure 2;
Figures 4A-B are cross-sectionalviews taken along line 4A-4A and 4B-4B of
Figure 3, respectively;
Figure 5 is a perspective view of a partial assembly of the interior of the
vessel of
the solid-liquid separator shown in Figure 3, revealing a portion of the fin
and disc
assembly;
Figure 6 is a perspective view of a partial assembly of the interior of the
vessel of
the solid-liquid separator illustrated in Figure 3, revealing a more complete
portion of the
fin and disc assembly;
Figures 7A, B and C are alternative fin embodiments which may be utilized in
the
separators of the present invention;
Figure 8 is a perspective view of a partial assembly of the interior of the
vessel of
the solid-liquid separator illustrated in Figure 3, revealing a completed fin
and disc
assembly;
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
3
Figure 9 is an elevational cross-sectional view taken along line 9-9 of
Figure 3;
Figure 10 is a cross-sectional view of the solid-liquid separator illustrated
in
Figure 3 showing the solid-liquid separator in operation;
Figure 11 is a cross-sectional view of one embodiment of a liquid-liquid
separator of the present invention;
Figure 12 is a perspective view of a partial assembly of the interior of the
vessel of the liquid-liquid separator shown in Figure 11, revealing a portion
of the fin
and perforated disc assembly;
Figures 13A-13C are block diagrams showing alternative embodiments of
valve assemblies controlling liquid flow into and out of the liquid-liquid
separator;
Figure 14 is a block diagram showing another embodiment of a valve
assembly controlling liquid flow into and out of the liquid-liquid separator;
Figure 15 is a block diagram overview of one process of the present invention
that uses the liquid-liquid separator in connection with a hydrocyclone;
Figure 16 is a cross-sectional view of an alternative embodiment of a
separator, wherein the spherical pressure vessel has been replaced with a
double
frusto-conical pressure vessel;
Figure 17 is a perspective view of a partial assembly of the interior of the
vessel of the separator shown in Figure 16;
Figure 18 is an elevational side view of an alternative embodiment of a
separator that can function as a solid-liquid and/or liquid-liquid separator;
Figure 19 is a cross sectional side view of the separator shown in Figure 18
without the supporting frame;
Figure 20 is a partially cutaway perspective view of a shaft assembly of the
separator shown in Figure 19;
Figure 21 is a cross sectional side view of the separator taken along line 21-
21
in Figure 19;
Figure 22 is an enlarged cross sectional view of the pressure vessel of the
separator shown in Figure 19;
Figure 23 is a cross sectional side view of an extraction tube of the
separator
shown in Figure 22;
Figure 24 is a perspective view of a nozzle of the extraction tube shown in
Figure 23;
Figure 25 is a plan view of a fin of the separator shown in Figure 22;
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
4
Figure 26 is a perspective view of a fin assembly of the separator shown in
Figure 19;
Figure 27 is a cross sectional side view of an alternative embodiment of the
extraction tube shown in Figure 24;
Figure 28 is a cross sectional side view of another alternative embodiment of
the extraction tube shown in Figure 24; and
Figure 29 is a perspective view of a fin assembly of the separator shown in
Figure 19 using solid discs.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention relates to systems and corresponding apparatus for
clarifying and/or separating components of a fluid stream. For example, in one
embodiment, the system can be used for clarifying water or other liquids that
have
been contaminated with particulate matter, including organic and inorganic
contaminants. The system can also be used for separating immiscible liquids
such as
an oil/water mixture or separating liquids of different density. Reference is
now made
to the drawings wherein like reference numbers refer to like unit operations
or
structures. The drawings are understood to be diagrammatic and/or schematic
and are
not necessarily drawn to scale nor are they to be limiting of the spirit and
scope of the
present invention.
Figure 1 is a block diagram overview of one embodiment of a system 8 that
uses an inventive separator as a solid-liquid separator 10 and/or an oil-water
separator
22. As illustrated in Figure 1, separators 10 and 22 are connected with a
variety of
other processing components. System 8 is configured for treatment of a fluid
feed
stream 12 that contains water, oil, and particulate. It is appreciated that
depending on
the content of feed stream 12 and the desired end components, select
components of
depicted system 8 can be removed, exchanged for other apparatus, or that
additional
components can be added.
Feed stream 12 may consist of a variety of different compositions, such as
water which includes pollutants like oil, bacterial contaminants, dissolved
metals and
minerals, and colloidally suspended solids. Feed stream 12 may originate, by
way of
example and not by limitation, from industrial facilities, animal product
processing
facilities, sewage treatment, municipal water treatment, the petroleum
industry, and
any other type of facility or system that has a fluid product or waste that
needs to be
clarified and/or separated.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
Feed stream 12 is initially feed to surge tank 14 which acts as a holding tank
to
store a large inflow of fluid. Surge tank 14 may include any commercially
available
surge tank, an earthen pond, or other liquid holding vessel. In other
embodiments,
surge tank 14 is not required and can be eliminated from the system. From
surge tank
5 14, the fluid follows a flow path 16 to a trash strainer 18 for removing
trash and
oversized particles which could clog the system. Exiting from trash strainer
18, the
fluid follows flow path 20 into oil-water separator 22 that divides an oil
stream 24
from a water stream 26. As will be discussed below in greater detail, oil-
water
separator 22 can also be periodically flushed to clean out particulate matter
collected
1o within separator 22. The particulate matter is flushed out through a solids
line 21 to a
filter 46 discussed below.
While a variety of oil-water separators may be employed, in one embodiment
oil-water separator 22, as will be discussed below in greater detail, is
comprised of a
separator having many of the same inventive features as will be discussed with
regard
to solid-liquid separator 10. Alternatively, oil-water separator 22 can
comprise an oil-
water separator such as those separators disclosed in U.S. Patent Nos.
5,387,342,
5,582,724 and 5,464,536.
Water stream 26 may be combined with a filter water stream 28 so as to form
a feed stream 29 that is feed to an electrostatic coagulator 32. Electrostatic
coagulator
32 operates to electrically sterilize the water by killing any living
organisms, breaking
down colloidal suspensions of impurities, and coalescing impurities into a
flocculent.
Such systems are available from Scott Powell Water Systems, Inc. of Denver,
Colorado.
A coagulated effluent stream 34 supplies a development tank 36 that typically
has a residence time of from about one to five minutes or longer. While in
development tank 36, the particle size of the flocculent grows. Effluent
stream 38
from development tank 36 supplies solid-liquid separator 10 which will be
discussed
below in greater detail. Solid-liquid separator 10 generates an particulate
stream 40
constituting the particulate matter and gas that has been removed from the
effluent
stream 38, and an clarified stream 42 constituting the clarified water or
other liquid.
The clarified water in clarified stream 42 is discharged either directly or
through a
post filter 45 to the environment or other designed destination. Particulate
stream 40
is supplied to filter 46 from which filter water stream 28 and a filter cake
48 are
generated.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
6
In one embodiment, gas and residual oil collected in the top of development
tank 36 can be directly drawn off through line 49 to filter 46. It is also
appreciated
that oil-water separator 22, electrostatic coagulator 32, development tank 36,
solid-
liquid separator 10, and filter 46 can each be operated under an elevated
pressure,
such as by the application of a pump, so as to facilitate desired flows
through the
system. The pressure may vary in one or more of the components 22, 32, 36, 10
and
46 so as to control flow in desired directions.
Depicted in Figure 2 is one embodiment of solid-liquid separator 10
incorporating features of the present invention. Solid-liquid separator 10
includes a
1o pressure vessel 60 which is driven by a motor 62. Although solid-liquid
separator 10
of the present invention can be manufactured in a variety of different sizes,
the
depicted embodiment is designed to process approximately 40 liters/minute. In
such
an embodiment, a 2.5 horsepower, 3440 RPM electric motor can be utilized.
Pressure vessel 60 is preferably mounted within a guard 64. Guard 64 merely
provides a shroud or housing as asafety mechanism to keep people and objects
away
from spinning pressure vessel 60. In the illustrated embodiment, a frame
assembly 66
is provided to which guard 64 is mounted via mounting fins 68. One of skill in
the art
will, of course, appreciate that guard 64 may be configured and attached to
frame
assembly 66 in a variety of ways.
Frame assembly 66 is further configured to provide support to the motor 62
and the bearing structure which supports pressure vessel 60. Solid-liquid
separator 10
includes a stationary inlet housing 70 configured to receive an inlet line 72.
Similarly,
a stationary outlet housing 74 is provided on the opposite end of the pressure
vessel
60 to which is attached an outlet removal line 76 and an outlet effluent line
78.
A pump 80 is used to receive and feed effluent stream 38 to solid-liquid
separator 10 through inlet line 72. Pump 80 pressurizes effluent stream 38 in
inlet
line 72 such that solid-liquid separator 10 operates under such pressure.
Hence, pump
80 must be capable of pumping effluent stream 38 at the flow rate capacity of
the
solid-liquid separator 10 while maintaining a desired pressure. In one
embodiment,
pump 80 maintains effluent stream 38 at a pressure in a range between about 1
psi
(6.89x103 Pa) to about 600 psi (4.14x106 Pa) with about 30 psi (2.07x105 Pa)
to about
125 psi (8.61x105 Pa) being more preferred. Pump 80 also produces flow rates
in a
range between about 3 liters/minute to about 1,000 liters/minute. Any
commercially
available pump which can create the above pressures and the desired flow rates
will
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
7
function for the desired purpose. Depending on the intended use, it is
appreciated that
the pressure range and flow rate can also be larger or smaller.
As illustrated in Figure 3, pressure vessel 60 is mounted for rotation about
rotational axis 90 which also coincides with the rotational axis of solid-
liquid
separator 10. Pressure vessel 60 includes a peripheral wall 92 having an
interior
surface 93 bounding a chamber 95. In the embodiment depicted, chamber 95 is in
the
shape of a sphere, although other configurations may be utilized. Because
vessel 60 is
mounted for rotation about axis 90, pressure vessel 60 will generally include
a
geometry comprising a body of rotation about axis 90.
Additionally, it is desirable, although not required, that the walls of
pressure
vessel 60 slope radially outward towards an equator 97 having a maximum
diameter
that encircles rotational axis 90. Thus, although a pressure vessel with
spherical walls
92 is one desired embodiment because of its efficient pressure bearing
qualities, other
curved-wall vessels, such as those having an oval, elliptical, or
symmetrically
irregular shape may be employed. Furthermore, straight-line configurations
such as
two truncated cones with their wide ends affixed together can be used.
Similarly, a
vessel having a cylindrical configuration at the edges and a center which is
formed by
truncated cones connected together can be used. In yet other embodiments,
vessel 60
need not have outwardly sloping walls. For example, vessel 60 can be
cylindrical or
have a polygonal transverse cross section.
Pressure vessel 60 may be made out of a variety of materials including
stainless steel, plastics, composites, filament wound structures, and other
conventional
materials. In one embodiment, pressure vessel 60 is capable of withstanding
pressures in a range between about 1 psi (6.89x103 Pa) to about 2,000 psi
(1.38x107
Pa) with about 100 psi (6.89x105 Pa) to about 1,000 psi (6.89x106 Pa) being
more
preferred. In the embodiment depicted, pressure vessel 60 is made out of
stainless
steel and has two halves for ease of manufacture and construction. The two
halves are
secured together such as by welding, bolts, or other conventional methods such
that a
seam is formed at equator 97 of vessel 60.
As illustrated in Figure 3, solid-liquid separator 10 includes a drive shaft
94 at
its inlet end 96 which is rigidly mounted to vessel 60. Drive shaft 94 is
configured to
engage motor 62 (Figure 2) as is known in the art. Drive shaft 94 is mounted
within a
hollow shaft 98 which is secured within inlet mounting collar 100. Inlet
mounting
collar 100, in turn, is secured to vessel 60 within a plurality of mounting
bolts 102, in
a manner known to one of skill in the art.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
8
Drive shaft 94, hollow shaft 98, and inlet mounting collar 100 are thus all
rigidly secured to each other and to vessel 60 by any of those methods known
in the
art, such as by welding or the use of bolts, such as mounting bolts 102 which
engage
an inlet mounting flange 104. These components comprise a drive assembly which
is
rigidly affixed to vessel 60 and, consequently, rotates with vessel 60.
The drive assembly is configured to engage inlet housing 70. Inlet housing 70
supports the drive assembly with an inlet bearing assembly 106 which, in this
embodiment, engages the inlet mounting collar 100. Inlet bearing assembly 106
is a
sealed ball bearing assembly resting in a pillow such as will be well known to
one of
skill in the art.
Inlet housing 70 is configured with a feed stream inlet 114 which is
configured
for receiving inlet line 72 (Figure 2) via any of those known attachment
methods
known in the art for providing fluid communication. As illustrated with
reference to
Figures 3 and 4A, inlet housing 70 is further configured with an annular
manifold
cavity 108 which surrounds hollow shaft 98. Hollow shaft 98 includes a
plurality of
access ports 110. Mechanical pump seals 112 are provided between hollow shaft
98
and inlet housing 70 on each side of manifold cavity 108, thereby providing a
fluid
seal while allowing relative rotational movement between inlet stationary
housing 70
and hollow shaft 98. Mechanical pump seals such as are available from A.W.
Chesterton Co. of Stoneham, Massachusetts function for the desired purpose.
With continued reference to Figure 3, the support structure for vessel 60 at
outlet end 120 is illustrated and described. As at inlet end 96, vessel 60 at
outlet end
120 is similarly configured with an outlet mounting flange 122. An outlet
mounting
collar 124 is attached to outlet mounting flange 122 with a number of bolts
102.
Outlet mounting collar 124 is supported on outlet housing 74 via an outlet
bearing
assembly 126.
Outlet housing 74 and outlet mounting collar 124 are each configured with a
hollow interior for receiving an exit tube 128 having a removal channel 130
therein.
As illustrated in Figure 4B, the hollow interior of outlet housing 74 and
outlet
mounting collar 124 is configured relative to exit tube 128 such that an
annular
effluent channel 132 is defined therebetween. Effluent channel 132 extends
exterior
of exit tube 128 and is in fluid communication with an effluent outlet 134
configured
in outlet housing 74. Referring again to Figure 3, in one embodiment effluent
outlet
134 includes a pressure relief valve 136 for maintaining pressure within
vessel 60.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
9
Pressure relief valve 136 may be a one-way, spring-loaded fail shut valve in
which the
spring force must be overcome by a sufficient fluid pressure to force the
valve open.
An outlet end 129 of exit tube 128 is overfit with mechanical pump seal 138.
The opposing end of mechanical pump seal 138 is rigidly affixed within a
circular
step configured in the interior end of outlet housing 74. Thus, mechanical
pump seal
138 acts as a fluid barrier between removal channel 130 and effluent channel
132 and
allows for relative rotational movement between exit tube 128 and outlet
housing 74.
The outlet end of outlet housing 74 is further configured with an exit orifice
140
which engages outlet removal line 76. Outlet removal line 76 is accessed
through an
1o exit valve 148 which may be a standard or solenoid valve, such as a ball
valve that is
commercially available.
Exit tube 128 also has an inlet end 131. In one embodiment, a plug 162 is
received within the opening at inlet end 131. A gas escape orifice 164 extends
through
plug 162 so as to establish fluid communication between the center of chamber
95 and
channel 130 extending through exit tube 128. Gas escape orifice 164 typically
has a
diameter in a range between about 0.02 inches (0.05 cm) to about 0.5 inches
(1.3 cm)
with about 0.02 inches (0.05 cm) to about 0.125 inches (0.3 cm) being more
preferred.
Depending on the intended use, this dimension can also be larger or smaller.
In an
alternative embodiment, inlet end 131 can simply be formed with a constricted
orifice
that communicates with removal channel 130, thereby precluding the need for
plug
162.
With continued reference to Figure 3, exit tube 128 extends to the center of
vessel 60. Solid-liquid separator 10 also includes a plurality of radially
outwardly
extending extraction tubes 160. Each extraction tube 160 has a first end 161
and an
opposing second end 163. Each first end 161 is in fluid communication with
exit tube
128 at inlet end 131 thereof. Extending through each extraction tube 160 is a
channel
having a diameter in a range from about 0.06 inches (0.15 cm) to about 2.0
inches (5
cm) with about 0.125 inches (03 cm) to about 0.5 inches (1.3 cm) being more
preferred. In other embodiments the diameter can be smaller or larger. In one
embodiment, eight extraction tubes 160 are employed, each spaced 45 degrees
from
the adjacent tube. In alternative embodiments, any number of extraction tubes
160
can be used. In one embodiment, a typical number of extraction tubes 160
ranges
from about 2 to about 144 with about 4 to about 24 being more preferred.
In yet another embodiment, extraction tubes 160 need not radially outwardly
project from exit tube 128 such that extraction tubes 160 are perpendicular to
exit tube
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
128. Rather, extraction tubes 160 can outwardly project from exit tube 128 at
an
angled orientation. For example, in one embodiment, the inside angle between
each
extraction tube 160 and exit tube 128 may be in a range between about 90 to
about
160 . In the embodiments where the inside angle is greater than 900, exit tube
128
5 can be shorter so that inlet end 131 of exit tube 128 couples with first end
161 of each
extraction tube 160. In yet other embodiments, the inside angle between each
extraction tube 160 and exit tube 128 can be less than 90 .
Extraction tubes 160 each extend outwardly an equal distance from the
rotational axis 90 of solid-liquid separator 10. Each extraction tube 160 has
an
to opening 166 at its second end 163 for receiving separated particulate
matter and fluid.
In operation, extraction tubes 160, as further explained below, assist in
defining a
boundary line between the collected particulate matter and the clarified
liquid. Thus,
the length of extraction tubes 160 is set to provide a predetermined boundary
line
within vessel 60. In one embodiment in which vessel 60 has a maximum inner
diameter of 19 inches at equator 97, extraction tubes 160 are configured to
leave a
0.25 inch (0.65 cm) space between opening 166 in tubes 160 and wall 92 of
vessel 60.
In alternative embodiments, including those of different sized vessels, the
space
between the opening 166 in extraction tubes 160 and wall 92 of vessel 60 is
typically
in a range between about 0.125 inches (0.3 cm) to about 2 inches (5 cm) with
about
0.25 inches (0.6 cm) to about 1 inch (2.5 cm) being more preferred. In other
embodiments, the space can be smaller or larger.
Vessel 60 is also configured with a plurality of fins and discs for channeling
fluid flow through vessel 60. One embodiment of solid-liquid separator 10
includes a
center disc 170, positioned in the center of vessel 60 and oriented
perpendicular to
rotational axis 90, as illustrated in Figure 3. Center disc 170 is configured
with a
central orifice which fits over plug 162. Center disc 170 extends in a
circular
configuration radially outward from plug 162. Outer edge 172 of disc 170 is
circular
(following the curvature of vessel 60) and is configured to provide an axial
flow
passage 174 between the edge 172 of disc 170 and wall 92 of vessel 60. Flow
passage
174 extends annularly about axis 90. Outer edge 172 is typically, although not
necessarily, disposed radially inward from opening 166 of extraction tubes
160. In
one embodiment, the distance between edge 172 of disc 170 and wall 92 of
vessel 60
is in a range between about 0.5 inches (1.3 cm) to about 4 inches (10 cm) with
about
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
11
0.8 inches (2 cm) to about 1.2 inches (3 cm) being more preferred. In other
embodiments, this distance can also be larger or smaller.
The depicted embodiment also includes four additional discs 176, 178, 202
and 204. Discs 176 and 202 are positioned on the inlet side of vessel 60 with
discs
178 and 204 positioned on the outlet side. Discs 176, 178, 202 and 204 are
used in
part to facilitate assembly of the solid-liquid separator 10 and to provide
structural
support during operation thereof. Alternatively, the solid-liquid separator 10
can be
assembled with fewer or greater numbers of assembly discs. It is also
envisioned that
the inventive solid-liquid separator 10 can be constructed without discs by
securing
the fins, as discussed below, directly to exit tube 128 and/or wall 92 of
vessel 60.
As illustrated in Figures 5 and 6, discs 176 and 202 include central orifices
180 which allow gas that collects at the center of the vessel 60 to be
extracted. Discs
178 and 204 are similarly configured with central orifices 182 slightly larger
than the
outside diameter of exit tube 128, thereby accommodating passage therethrough
of
exit tube 128. V-notches 210 may be formed, such as by being laser cut, into
outer
edge 172 of disc 170. These v-notches minimize the disturbance of the
collected
particulate matter as the clarified water flows around disc 170. In one
embodiment,
these v-notches 210 are cut at the edge 172 of disc 170 having a width in a
range
between about 0.1 inch (0.25 cm) to about 1 inch (2.5 cm) and a depth in a
range
between about 0.1 inch (0.25 cm) to about 1 inch (2.5 cm). The number of v-
notches
210 that are cut into center disc 170 between each pair of fins 184 is
typically in a
range between about three notches to about eight notches. Alternatively, the
number
and size of these v-notches 210 can be increased or reduced.
Referring now to Figure 5, solid-liquid separator 10 also includes a plurality
of
radial fins 184. Each fin 184 has an inside edge 186 which is generally
parallel to
rotational axis 90 and an outside edge 188 which generally follows the
curvature of
vessel 60. Thus, in the configuration illustrated herein, in which spherical
vessel 60 is
employed, outside edge 188 of fins 184 has a substantially semi-circular
configuration.
In the embodiment illustrated in Figure 8, two types of fins 184 are used:
trimmed fins 212 and untrimmed fins 214. As depicted in Figure 7A, each
trimmed
fin 212 includes a substantially flat inside edge 186 and an opposing outside
edge
188. Outside edge 188 includes a substantially flat side portion 187
orthogonally
projecting from each end of inside edge 186, a centrally disposed
substantially flat
nose portion 189 disposed substantially parallel to inside edge 186, and a
curved
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
12
shoulder portion 191 extending from each side portion 187 to opposing ends of
nose
portion 189.
As illustrated in Figure 7B, each untrimmed fin 214 includes a substantially
flat inside edge 186 and an opposing outside edge 188. Outside edge 188
includes a
substantially flat side portion 187 orthogonally projecting from each end of
inside
edge 186 and a curved face portion 193 extending between each side portion
187. A
centrally disposed semi-circular notch 194 is formed on face portion 193.
An alternative fin 215 is illustrated in Figure 7C. Fin 215 has substantially
the
same configuration as untrimmed fin 214 except that notch 194 is replaced with
holes
196 extending through fin 215. Such holes 196 typically have a diameter in a
range
between about 0.5 inches (1.3 cm) to about 1.5 inches (3.8 cm).
Fins 184 are positioned within chamber 95 of vessel 60 perpendicularly to
discs 170, 176, 178, 202 and 204,as best illustrated in Figures 5 and 6. Each
disc is
provided with a slot 198 which corresponds to each fin 184. Slots 200, which
correspond to each disc 170, 176, 178, 202 and 204, are also configured in
each fin
184. Fins 184 and discs 170, 176, 178, 202 and 204 are in one embodiment
formed of
stainless steel but can also be formed from plastics, composites, and other
sufficiently
strong material. Slots 198 and 200 may be formed using any conventional method
such as by laser cutting. Slots 198 and 200 are configured to allow the fins
and discs
to engage each other in a slip fit, mating relationship. Thus, slots 198
configured in
discs 170, 176, 178, 202 and 204 have a width at least as great as the
thickness of fins
184. Similarly, slots 200 configured in fins 184, have a width at least as
great as the
thickness of the discs 170, 176, 178, 202 and 204 which correspond to these
slots.
The fin and disc assembly within vessel 60 is thus assembled as illustrated in
Figure 5 by positioning outlet discs 204 and 178 over exit tube 128. Center
disc 170
as seen in Figure 6 is then placed about plug 162 and some fins 184 are
engaged into
their corresponding slots on the discs 170 and 178 while simultaneously
engaging the
discs with the corresponding slots on fins 184. When fin 184 is thus placed
into
mating engagement with a disc, virtually all relative movement between the
disc and
the fin is prohibited. Inlet discs 176 and 202 are then placed into mating
engagement
with slots 200 on fins 184. With all five discs 170, 176, 178, 202 and 204 now
in
position, the remaining fins are installed by sliding them radially into
position, until
the interior configuration of the vessel 60 is complete as illustrated in
Figure 8. Slots
198 and 200 are simply one way of securing the fins and discs together. In
alternative
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
13
embodiments, the fins and discs can be welded, clamped, integrally molded, or
otherwise secured together using conventional methods.
In the depicted embodiment, twenty four fins 184 are utilized in vessel 60, as
illustrated in Figures 8 and 9. In alternative embodiments, the number of fins
184 is
typically in a range between about 8 to about 144 with about 12 to about 48
being
more preferred. As best depicted in Figure 3, 8, and 9, the assembled fins 184
radially
outwardly project from rotational axis 90 in substantially parallel alignment
with
rotational axis 90. Each inside edge 186 is spaced apart from the center of
rotational
axis 90 so that a channel 219, depicted in Figure 3, is formed that extends
from inlet
1o end 96 to gas escape orifice 164. Channel 219 has a diameter typically in a
range
between about 0.25 inches (0.6 cm) to about 2 inches (5 cm) with about 0.25
inches
(0.6 cm) to about 1 inch (2.5 cm) being more preferred. Depending on the
intended
use, the diameter can also be smaller or larger. As illustrated in Figures 7A
and 7B
the inside edge 186 of each fin 184 is cut to prevent interference with exit
tube 128
and gas escape plug 162.
To accommodate the eight radial extraction tubes 160, trimmed fins 212 are
modified with a central notch 216 as illustrated in Figure 5. Notch 216 is
sized to
allow some degree of intersection of trimmed fins 212 with extraction tubes
160, as
illustrated in Figure 9. Hence, in the depicted embodiment, sixteen trimmed
fins 212
as modified with a notch 216 are utilized in combination with eight untrimmed
fins
214 which have not been so modified.
In an alternative embodiment, it is appreciated that fins 184 need not
radially
outwardly project in alignment with rotational axis 90. Rather, inside edge
186 of
each fin 184 can be offset from alignment rotational axis 90 and still be
retained in
position by the discs. As used in the specification and appended claims, the
phrase,
"fin projecting from toward the rotational axis" is broadly intended to
include
embodiments where an inside edge of a fin is disposed in a plane that is
either aligned
with or offset from the rotational axis, where at least a portion of the
inside edge is
directly disposed along the rotational axis or is radially spaced outward from
the
3o rotational axis, and/or where the inside edge is parallel with or angled
relative to the
rotational axis.
With the fins and discs assembled about exit tube 128 as illustrated in Figure
8, the internal assembly is enclosed within chamber 95 of vessel 60. In one
embodiment, vessel 60 is comprised of two halves which are secured together,
such as
by welding or bolting with a seal such as a gasket or o-ring disposed
therebetween.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
14
By covering the internal assembly of Figure 8 within wall 92 of vessel 60, the
fins and
discs become locked to each other in relative engagement and no welding is
needed to
hold them secure.
Specifically, as depicted in Figure 10, flat side portions 187 of each fin 184
are
disposed adjacent to mounting flanges 104 and 122. Curved shoulder portions
188 of
trimmed fins 212 are disposed adjacent to wall 92. Similarly, curved face
portion 193
of untrimmed fins 214 are also disposed adjacent to wall 92. Side portions
187,
shoulder portions 188, and face portion 193 of fins 184 can be directly biased
against
vessel 60. Alternatively, a small gap, typically less than about 1/4 inch, can
be
formed between vessel 60 and portions 187, 188, and 193. As illustrated in
Figure 9,
the positioning of fins 184 adjacent to wall 92 results in the formation of a
plurality of
discrete flow channels 218 through vessel 60 along the rotational axis. Each
flow
channel 218, however, is partially blocked by the intersection of the various
discs 170,
176, 178, 202, and 204. As a result of the discs, fluid traveling through flow
channels
218 is required to flow around the outer edge of the discs.
Returning to Figure 10, an underflow passage 190 is formed between flat nose
portion 189 of trimmed fins 214 and wall 92. Underflow passage 190 enables
fluid to
flow between discrete flow channels 218 at equator 97. In one embodiment, the
maximum gap between flat nose portion 189 of trimmed fin 214 and wall 92 is in
a
range between about 0.125 inches (0.3 cm) to about 2 inches (5 cm) with about
0.25
inches (0.6 cm) to about 1 inch (2.5 cm) being more preferred. In other
embodiments,
the maximum gap can be larger or smaller. Although not required, in one
embodiment
flat nose portion 189 of each fin 184 is positioned radially inward from
opening 166
of each corresponding extraction tube 160.
It is of course envisioned that fins 184 can be formed in a variety of
different
configurations to facilitate underflow passage 190 between flow channels 218.
For
example, trimmed fins 212 can be replaced with alternative fins 215. In this
embodiment, holes 196 facilitate underflow passage 190. In yet other
embodiments,
notches, slots, holes, grooves, and the like can be formed in a fin 184 to
facilitate
underflow passage 190.
Notch 194 (Figure 7B) formed in untrimmed fins 214 is designed to perform
two functions. First, in an embodiment where a seam is formed at equator 97,
such as
an inside flange, notch 194 provides space to receive the seam. Notch 194 also
functions to allow at least some flow between flow channels 218 separated by
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
untrimmed fins 214. Fluid flow through notch 194 thus helps to insure that
boundary
layers and flow rates are the same in each flow channel 218.
Once the internal assembly is enclosed within vessel 60, the inlet and outlet
mounting collars 100, 124, the bearing assemblies, and housings assembled as
5 described above are bolted or otherwise secured to vessel 60 using
conventional
methods known to those skilled in the art.
In operation, as illustrated in Figure 2, rotation of the vessel 60 is
commenced
by turning on motor 62. Motor 62 typically causes vessel 60 to rotate with a
rotational velocity in a range between about 600 rotations/minute to about
10,000
to rotations/minute with about 1,200 rotations/minute to about 3,600
rotations/minute
being more preferred. A stream 38 is received by pump 80 which pumps stream 38
into the solid-liquid separator 10 through inlet line 72. Stream 38 is
preferably
pressurized by pump 80 such that a hydraulic pressure is maintained within
vessel 60
during operation of the solid-liquid separator 10. In one embodiment vessel 60
of
15 solid-liquid separator 10 operates under a hydraulic pressure in a range
between about
1 psi (6.89x103 Pa) to about 600 psi (4.14x106 Pa) with about 30 psi (2.07x105
Pa) to
about 125 psi (8.61x105 Pa) being more preferred. Depending on the intended
use,
the rotational velocity and operating pressure can be greater or smaller.
In addition to the hydraulic pressure applied to vessel 60 by stream 38, a
centrifugal force is applied to stream 38 and vessel 60 as a result of the
rotation of
vessel 60. This centrifugal force increases as the distance away from
rotational axis
90 increases. As such, the total force at the perimeter of vessel 60 may be
several
times that of the hydraulic pressure.
Stream 38 may include virtually any liquid which has been contaminated with
a particulate component having a density greater than the liquid. For most
applications, however, the liquid will be water. Thus, although water is
referred to
herein as the liquid being clarified, it will be understood that solid-liquid
separator 10
of the present invention may be used to clarify a variety of liquids.
As illustrated in Figure 10, feed stream 38 enters the solid-liquid separator
10
through feed stream inlet 114. As feed stream 38 reaches the rotating hollow
shaft 98,
it is forced through access ports 110 (see also Figure 4) into the hollow
shaft 98 where
the stream is accelerated to the same rotational velocity as vessel 60. Flow
through
rotating hollow shaft 98 proceeds in the direction of arrow A. Upon reaching
the
entrance to vessel 60 adjacent inlet mounting flange 104, the centrifugal
force
imposed due to the rotation of vessel 60 pushes the stream radially outwardly
towards
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
16
wall 92 of vessel 60. As the stream enters vessel 60, it enters one of the
flow channels
218 (Figure 9) and proceeds to fill vessel 60.
Flow channels 218 help eliminate the Coriolis effect. That is, if fins 184
were
removed, as the fluid enters vessel 60, the fluid would swirl in a vortex.
Such swirling
produces a turbulent flow that suspends particles within the fluid. As
discussed
below, in one embodiment solid-liquid separator 10 operates by settling the
particulate matter against or adjacent to wall 92 of vessel 60 from where it
is
subsequently removed. By passing the fluid through discrete flow channels 218,
swirling of the fluid is substantially eliminated. The fluid travels in a
substantially
laminar flow wherein the fluid rotates at the same speed as vessel 60. As a
result, the
potential for settling particulate within the liquid is maximized.
As stream 38 enters the vessel, it is forced around disc 176 along the
direction
of arrows B. Within vessel 60, the stream is subjected to the tremendous
centrifugal
forces imposed on it due to the rotation of vessel 60. Thus, the more dense
component of the stream, i.e., the particulate matter, flows radially
outwardly while
the less dense component flows radially inwardly or stays on top. In one
embodiment, the centrifugal forces present in solid-liquid separator 10
produce an
average of approximately 500 g's to about 2,000 g's on the fluid mixture. The
centrifugal force rapidly clarifies the fluid producing a low liquid content
of the more
dense particulate matter. Solid-liquid separator 10 can thus achieve in
minutes or
seconds the amount of separation that a static tank separator takes hours to
achieve.
As discussed above, the particulate matter in stream 38 is forced by the
rotation of vessel 60 to accumulate against wall 92 at equator 97. The
accumulated
particulate matter is identified as collected solids 224. A boundary line 228
is defined
between collected solids 224 and the clarified water 226 radially inwardly
disposed
therefrom. Collected solids 224 are allowed to accumulate and boundary line
228 rise
until boundary line 228 is located radially inward of opening 166 of
extraction tubes
160 (a condition illustrated in Figure 10). Collected solids 224 are
subsequently
extracted from pressure vessel 60 through extraction tubes 160 as described
below.
Water flowing around the edge of disc 170 through axial flow passage 174 can
stir up collected solids 224 that have settled at the largest dimension radius
or equator
97 of pressure vessel 60. Although not always, in one embodiment this stirring
caused by eddy effects works in opposition to the purpose of solid-liquid
separator 10.
Therefore, notches such as v-notches 210 previously discussed with regard to
Figure 6
may be cut in the outer perimeter of disc 170. The notches minimize stirring
by
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
17
reducing the force of the water flow around disc 170, thereby reducing the
eddy
effects. Thus the v-notches 210 maintain boundary layer 228 between collected
solids
224 and clarified water 226.
Apart from functioning to support fins 184, the various discs, particularly
disc
170, function to assist in the removal of the particulate matter. That is, all
fluid that
enters vessel 60 must flow either to or around the outer edge of disc 170
before it can
exit vessel 60. By forcing all of the fluid to flow to the outer edge of disc
170 at
equator 97, all of the fluid is subject to the greatest centrifugal force
produced by the
rotation of vessel 60, thereby ensuring that the highest concentration of
particulate
matter is removed from the incoming fluid. Discs 176 and 178 also function for
this
purpose. Furthermore, by positioning discs 176 and 178 on opposing sides of
disc
170, the fluid flows radially inward and outward as it moves between the
discs. This
radial movement of the fluid increases the retention time of the fluid within
the vessel,
thereby subjecting the fluid to the centrifugal force of the vessel for a
longer period of
time. As a result, a larger portion of the particulate matter is removed. In
an
alternative embodiment, however, the inventive solid-liquid separator can be
operated
without the use of the discs, particularly disc 170.
Because gases may occasionally be found in fed stream 38, a gas layer 230
may form about axis 90 on the inlet side of vessel 60. Disc 170 effectively
serves as a
barrier between the inlet side and the outlet side of vessel 60. Hence, gases
found
within the feed stream will generally be found only on the inlet side of
vessel 60
because they are likely to be separated before the liquid passes through axial
flow
passage 174.
As feed stream 38 continues to flow into the vessel 60, the fluid passes
around
the outer perimeter of center disc 170 and into the outlet side of vessel 60.
Clarified
water 226, which can be other fluids in other embodiments, fills the outlet
side of
vessel 60 and then flows out through effluent channel 132. Clarified water 226
subsequently exits solid-liquid separator 10 through effluent outlet 134 and
pressure
relief valve 136. Pressure relief valve 136 only opens when the back pressure
in
effluent outlet 134 overcomes the spring force for the valve, thereby ensuring
that a
predetermined pressure is maintained inside vessel 60. In an alternative
embodiment,
pressure relief valve 136 can be replaced with other operating systems that
perform
the same function. For example, pressure relief valve 136 can be replaced with
an
electronically operated valve and a pressure sensor. The valve is
electronically
opened when the pressure sensor senses a predetermined pressure within vessel
60 or
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
18
outlet 134. In other embodiments, valve 136 can be self-adjusting so as to
allow
clarified water 226 to continually flow therethrough at a given pressure.
Should the
flow increase or decrease, valve 136 automatically opens or closes a
proportional
amount so that the pressure is held substantially constant.
Boundary line 228 is maintained at a desired level by periodically opening
valve 148 and allowing collected solids 224 to be extracted through extraction
tubes
160. When valve 148 is opened, a pressure gradient is created between the
interior of
vessel 60 and outlet removal line 76. Flow of collected solids 224 proceeds
from the
higher pressure environment within vessel 60 to the lower pressure through
extraction
1o tubes 160. This pressure differential may be created a number of ways, such
as by
operating vessel 60 at ambient pressure and imposing a negative pressure on
extraction tubes 160, or, as is presently depicted, operating vessel 60 under
pressure
and imposing extraction tubes 160 to a near ambient pressure.
Recognizing that the eight extraction tubes 160 only extend into eight of the
flow channels 218 (Figure 9), boundary line 228 drops in these flow channels
218 as
collected solids 224 are extracted. As boundary line 228 in these flow
channels 218
drops, collected solids 224 from adjacent flow channels 218 flows through
underflow
passage 190 to maintain boundary line 228 at a generally constant level
throughout
the circumference of vessel 60. In an alternative embodiment, it is envisioned
that an
extraction tube 160 can be feed to each discrete flow channel 218. In this
embodiment, it is not necessary to have underflow passage 190 between flow
channels 218, i.e., fins 184 can extend all the way to wall 92 of vessel 60
along the
length of fins 184.
When exit valve 148 is opened, any gas which has built up inside vessel 60 to
form a gas layer 230 will immediately begin escaping through orifice 164 of
plug 162
which is in fluid communication with removal channel 130. Thus, orifice 164
should
preferably be sized such that any anticipated gas buildup may be removed
through the
periodic opening of valve 148. Orifice 164, however, should be sufficiently
small so
as to enable sufficient draw on extraction tubes 160 to remove collected
solids 224.
Thus, the size of orifice 164 depends in part upon the constituency and nature
of the
fluid flow. In one embodiment, orifice 164 has a threaded diameter of
approximately
0.375 inch (1 cm). This 0.375 inch (1 cm) orifice is threaded to allow an
insert
whereby the orifice diameter may be reduced or even totally occluded,
depending
upon the insert selected. An insert may be threaded into orifice 164 even
after
construction of the pressure vessel 60 because orifice 164 remains accessible
through
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
19
exit orifice 140 and removal channel 130. The adjustable nature of this
orifice
diameter allows orifice 164 to be tailored for different fluid flows while
using the
same solid-liquid separator 10.
In one embodiment of the present invention, spherical vessel 60 has an inside
diameter of about 19 inches (48 cm) and is capable of processing approximately
38
liters of water each minute. This provides a residence time of approximately
1.5
minutes in solid-liquid separator 10 while subjecting the water to an average
of
approximately 700 g forces. This is roughly the equivalent of 2 hours of
residence
time in a static clarifier having the same capacity. In one embodiment, the
solid-
liquid separator is capable of clarifying water to remove at least 99% of
solids. In
alternative embodiments, the present invention envisions that typical vessels
can be
formed having a maximum inside diameter in a range between about 6 inches (15
cm)
to about 120 inches (300 cm) with about 12 inches (30 cm) to about 60 inches
(150
cm) being more preferred. Such vessels can be designed to process fluid at a
rate in a
range from about 0 liters/minute to about 4,000 liters/minute with about 1
liter/minute
to about 1,000 liters/minute being more preferred. It is appreciated that in
other
embodiments, the above variables can be larger or smaller.
The resulting particulate stream 40 is passed through a bag filter, filter
press,
and/or belt filter to remove remaining water and to "cake" the solids. The
"caked"
solids may then be disposed of by composting or other method known in the art.
Ultimately, the disposal method will depend upon the composition of the
"caked"
solids. For instance, solids containing heavy metals cannot be composted and
other
appropriate disposal methods will be used.
To shut down solid-liquid separator 10, the pump and motor are turned off,
then vessel 60 is drained and flushed. Alternatively, fluid may simply be left
within
the vessel 60 during non-use.
In one embodiment, depending on the operating parameters and the particle
matter being collected, collected solids 224 can be difficult to fully extract
from
vessel 60 through extraction tubes 160. For example, collected solids 224 can
be
caked on wall 92 to such an extent that they do not freely flow into
extraction tubes
160. In one approach to more easily and fully removing collected solids 224,
the
inflow of stream 38 to vessel 60 and the outflow of clarified water 226 from
vessel 60
can be momentarily stopped. While vessel 60 continues to rotate, a removal
stream
can be pumped into removal channel 130 of exit tube 128 so that the removal
stream
passes down through extraction tubes 160 and into vessel 60.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
As the removal stream passes into vessel 60, the removal stream resuspends
the caked solids into surrounding fluid. The centrifugal force, however, keeps
the
particulate matter substantially adjacent to perimeter wall 92. Once the
particulate
matter is resuspended in a less dense phase, extraction tubes 160 can return
to their
5 original operation where the fluid containing the resuspended particulate
matter is
drawn out of vessel 60 through extraction tubes 160 and exit tube 128. Once a
desired amount of the particular matter is removed, flow through extraction
tubes 160
can be closed while rotating vessel 60 resettles the particulate matter
against
peripheral wall 92. Once the particulate matter is sufficiently settled, feed
stream 38
1o and clarified water can again flow into and out of vessel 60.
As will be discussed below in greater detail different forms of nozzles can be
placed at then end of extraction tubes 160 for more efficiently resuspended
the
particulate matter. Furthermore, a separate tube can be used to deliver the
removal
stream into vessel 60.
15 Depicted in Figures 11 and 12, another embodiment of the present invention
relates to a liquid-liquid separator 244 that uses a similar construction to
solid-liquid
separator 10 depicted in Figures 2-10. In contrast to solid-liquid separator
10 that is
primarily designed to remove particulate from a fluid, liquid-liquid separator
244 is
primarily designed to separate a mixed liquid of two or more immiscible
liquids such
20 as oil and water or any other types of immiscible liquids. Liquid-liquid
separator 224
can thus be used as oil-water separator 22.
Figure 12 illustrate a subassembly 232 of liquid-liquid separator 244.
Subassembly 232 includes a solid inlet side minor disk 234 similar to inlet
side minor
disk 176 depicted in Figure 6. A center disk 236 is depicted as having a
plurality of
perforations 238. Perforations 238 allow for the passage of the liquids
therethrough.
Additionally, an outlet side minor disk 240 is also depicted as having a
plurality of
perforations 238 extending therethrough.
As depicted in Figure 11, the remainder of subassembly 232 and the vessel in
which subassembly 232 is disposed are substantially the same as that
previously
discussed with regard to solid-liquid separator 10. As such, like elements are
identified by like reference characters. Furthermore, the alternatives
discussed above
with regard to solid-liquid separator 10 are also applicable to liquid-liquid
separator
244.
Liquid-liquid separator 244 also operates in a manner similar to solid-liquid
separator 10. For example, with vessel 60 rotating, the mixed liquid is pumped
into
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
21
inlet 114 so as to flow down hollow shaft 98 along arrow A. Upon reaching the
entrance to vessel 60, the mixed liquid enters one of the flow channels 218
(Figure 9)
and proceeds to fill vessel 60. As a result of the centrifugal force produced
by the
rotation of vessel 60 and the impact of the mixed liquid against minor disk
234, the
mixed liquid is pushed radially outwardly towards wall 92 of vessel 60 and
around
disk 234.
The mixed liquid includes a heavy component 241 and a light component 243
which are defined by their relative densities. It is appreciated that heavy
component
241 may also include comprise particulate matter. Where the mixed liquid
includes
1o more than two immiscible liquids, heavy component 241 or light component
243 can
be defined to include more than one liquid. The drawn off liquid that includes
more
than one liquid can subsequently be processed through a second liquid-liquid
separator 244 so as to separate the liquids therein.
As a result of the applied centrifugal force, heavy component 241 flows
toward wall 92 at equator 97. Light component 243 flows toward the center or
rotational axis 90 of vessel 60. As a result, a boundary line 245 is formed
between
heavy component 241 and light component 243. Boundary line 245 is maintained
within a range of radial distances away from rotational axis 90. This liquid-
liquid
boundary line 245 is analogous to boundary line 228 depicted in Figure 10 for
solid-
liquid separator 10. In contrast, however, liquid-liquid boundary line 245 is
typically
positioned at a radial distance from rotational axis 90 in a range from about
1/5 to
about 4/5 the distance between rotational axis 90 and the maximum diameter at
equator 97, preferably from about 1/4 to about 3/4 the distance, even more
preferably
from about 1/3 to about 2/3 the distance. In other embodiments, the distance
can be
smaller or larger.
As a result of perforations 238 extending through discs 236 and 240, light
component 243 and gas 230 can flow through discs 236 and 240 and out effluent
channel 132. Since gas 230 exits with light component 243, there is no need
for a gas
escape orifice at inlet end 131 of exit tube 128. In this embodiment, discs
236 and
240 function primarily as supports for fins 184 and thus can be any desired
configuration. Alternatively, discs 236 and 240 can be removed.
Heavy component 241 is removed from vessel 60 through extraction tubes 160
and exit tube 128. Where there are fewer extraction tubes 160 than discrete
flow
channels 218, underflow passages 190 are formed between discrete flow channels
218
so that boundary line 245 is constant for all flow channels 218. Since
boundary line
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
22
245 is typically closer to rotational axis 90 than boundary line 189, second
end 163 of
extraction tubes 160 can be moved closer to rotational axis 90.
In one embodiment of the present invention, means are provided for
pressurizing the fluid within pressure vessel 60 so as to automatically
control the
position of boundary line 245 within pressure vessel 60 as the ratio of light
component and heavy component of the fluid entering pressure vessel 60
changes.
Several alternative examples of such means are described below. By way of
example
and not by limitation, depicted in Figures 11 and 13A is one embodiment of a
control
system 290 for removing the separated liquids from liquid-liquid separator
244.
1o Specifically, a supply stream 30 containing two immiscible liquids is fed
to liquid-
liquid separator 244 where the two liquids are separated within pressure
vessel 60 into
heavy component 241 and light component 243 as discussed above. Control system
290 includes a first valve 248 coupled with effluent line 78 and a second
valve 256
coupled with removal line 76.
According to the present invention, a pressure differential is maintained
between first valve 248 and second valve 256. The pressure differential is
needed to
maintain boundary line 245 at a defined radial distance from rotational axis
90 such
that only light component 243 exits through effluent channel 132 and effluent
line 78
and only heavy component 241 exits through extraction tubes 160, exit tube
128, and
removal line 76. Failure to establish and maintain a pressure differential
between
valves 248 and 256 can result in boundary line 245 extending beyond extraction
tubes
160 such that a portion of light component 243 exits with heavy component 241
through extraction tubes 160 or can result in boundary line extending into
effluent
channel 132 such that a portion of heavy component 241 exits with light
component
243 through effluent channel 132.
The pressure differential is based on the operating properties of separator
244,
such as rotational velocity, and the material properties of supply stream 30,
such as
the density and viscosity of the at least two immiscible liquids contained
within
supply stream 30. The pressure differential is also based on the desired
location of
3o boundary line 245 within vessel 60. It is appreciated that in some
embodiments the
pressure differential can be zero or substantially zero so as to maintain
boundary line
245 at the desired location.
In practice, the pressure differential can be empirically determined. For
example, initially first valve 248 is set to operate at a first pressure. That
is, first
valve 248 maintains the exiting light component 243 at the first pressure
while
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
23
enabling exiting light component 243 to continually flow through first valve
248.
Accordingly, if the flow of exiting light component 243 decreases, first valve
248
automatically closes a corresponding amount so as to maintain the first
pressure. In
this regard, first valve 248 can comprises a back-pressure regulator such as a
Fisher
98L made by Fisher Controls International, Inc., out of Marshall Town, Iowa.
Alternatively, first valve 248 can comprise a piloted or controlled back-
pressure
regulator, also available from by Fisher Controls International, Inc., which
operates in
communication with a pressure sensor 246 coupled effluent line 78. In either
the
above embodiments or other alternative valve configurations, first valve 248
is
1o configured to automatically adjust so as to maintain a desired pressure on
exiting light
component 243 as the flow rate thereof changes. Where the flow rate is
substantially
constant, first valve 248 can be configured for manual rather than automatic
adjustment.
The amount of first pressure is in some regards arbitrary since it is the
pressure
differential that controls the position of boundary line 245. In one
embodiment,
however, first pressure is typically in a range between about 1 psi (6.89x103
Pa) to
about 600 psi (4.14x106 Pa) with about 30 psi (2.07x105 Pa) to about 125 psi
(8.61x105 Pa) being more preferred. In other embodiments, the pressure can be
greater or smaller.
Once the first pressure for first valve 248 is set, second valve 256 is
initially
set to operate at the same pressure. Liquid-liquid separator 244 is then
operated at a
flow rate for supply stream 30 and at a defined rotational velocity for vessel
60. The
operating pressure for second valve 256 is then incrementally varied in
opposite
directions so as to determine the extreme operating pressures for second valve
256.
For example, the operating pressure for second valve 256 can be incrementally
decreased and then incrementally increased so as to determine the pressures
for
second valve 256 at which light component 243 first starts to flow out of
removal line
76 with heavy component 241 and heavy component 241 first starts to flow out
of
effluent line 78 with light component 243.
Once the two extreme operating pressures for second valve 256 are
determined, second valve 256 is set to operate at a pressure between the two
extreme
pressures. This places boundary line 245 substantially centrally between the
opening
to effluent channel 132 and opening 166 to extraction tubes 160.
Alternatively,
second valve 256 can be set to operate at any desired pressure between the two
extreme pressures. The resulting pressure difference between first valve 248
and
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
24
second valve 256 defines the pressure differential. Second valve 256 can
comprise
the same type of valves as discussed above with regard to first valve 248. As
such, in
one embodiment, second valve 256 can operate in conjunction with a pressure
sensor
252 coupled with removal line 76.
One of the unique benefits of the inventive system is its ability to
compensate
for changes in the ratio of the two immiscible liquids in supply stream 30.
For
example, assuming an oil/water supply stream 30 feeds liquid-liquid separator
244 at
a 50/50 mixture. At a given time, the 50/50 mixture suddenly experiences a
load
change to 10% oil and 90% water. Where the rotational velocity of liquid-
liquid
separator 244 remains substantially constant, an increased amount of water
(heavy
component 241) will tend to cause boundary line 245 to move toward rotational
axis
90. Accordingly, the pressure sensed at first valve 248 will decrease while
the
pressure sensed at second valve 256 will increase. As a result, second valve
256 will
automatically close slightly and first valve 248 will automatically open
slightly. As a
result, the operating pressures for valves 248 and 256 and the pressure
differential
between valves 248 and 256 are continually held relatively constant even
though the
ratio of liquids in supply stream 30 may continually change. As such, the
position of
boundary line 245 is held relatively constant within vessel 60.
A 100% water supply stream 30 or a 100% oil supply stream 30 may also be
controlled by maintaining boundary line 245 within the preferred distance
range from
rotational axis 90. For example, where a 100% oil supply stream 30 is fed to
liquid-
liquid separator 244, second valve 256 will eventually shut entirely in order
to
maintain the liquid-liquid interface within the preferred distance range away
from
rotational axis 90. Accordingly, where all liquid in supply stream 30 is oil,
the oil
will move through liquid-liquid separator 244 substantially without any mixing
with
the water that, under this situation, would be substantially stagnant therein.
Another embodiment of a control system 294 is depicted in Figure 13B. Like
elements between control system 290 and 294 are depicted by like reference
characters. In contrast to control system 290 where second valve 256 measures
the
pressure in removal line 76, in control system 294 pressure sensor 252 is
coupled with
effluent line 78. A signal line 254 couples sensor 252 to second valve 256. In
this
embodiment, second valve 256 is set to operate at a pressure differential
relative to
the set operating pressure of first valve 248. By way of example, where first
valve
248 is set to operate at 20 psi, second valve 256 may be set to operate at a
pressure of
+5 psi relative to the sensed pressure in effluent line 78. Accordingly,
although both
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
valves 248 and 256 measure the pressure in effluent line 78, a predefined
pressure
differential is maintained between the two valves. Although sensors 246 and
252 are
shown in Figure 13 as both being coupled with effluent line 78, in an
alternative
embodiment sensors 246 and 252 can each be coupled with removal line 76. In
one
5 embodiment second valve 256 may be a differential pressure regulator such as
a
Fisher 98LD made by Fisher Controls International, Inc., out of Marshall Town,
Iowa.
In yet another embodiment, it is appreciated that first valve 248 in control
system 294 can be configured such that it does not adjust the pressure on
effluent line
78 as the flow rate of fluid passing therethrough changes. For example, first
valve
10 248 can be configured such that as the amount of exiting light component
243 passing
therethrough decreases, the fluid pressure within effluent line 78 can also be
allowed
to decrease. However, since second valve 256 is set to operate at a pressure
relative
to the pressure of effluent line 78, the operating pressure of second valve
256 also
decreases, thereby maintaining the desired pressure differential between
valves 248
15 and 256.
In yet another embodiment depicted in Figure 13C, a controller 260 is used to
withdraw the separated fluids from liquid-liquid separator 244. Signals are
transmitted from first pressure sensor 246 by use of a first transmitter 262
that
operates, by way of non-limiting example with a 4-20 mA signal. Similarly,
first
20 valve 248 transmits a signal by use of a first I/P converter 264 also with
a 4-20 mA
signal. First I/P converter 264 converts a 4-20 mA control signal to a
pneumatic
signal in order to operate first valve 248. Removal line 76 is also configured
with
second pressure sensor 252, a second transmitter 266, a second valve 256, and
a
second I/P converter 268.
25 According to the present invention, when a load disturbance occurs within
supply stream 30, first pressure sensor 246 and second pressure sensor 252
detect a
change in respective pressures between exiting heavy component 241 passing
through
removal line 76 and exiting light component 243 passing through effluent line
78.
According to the present invention, such a load disturbance will be noted by
controller
260 and respective valves 248 and 256 will be adjusted in order to maintain
boundary
line 245 at a preferred distance range away from rotational axis 90. According
to this
embodiment of the present invention, the pressure differential is maintained
by the
control of first valve 248 and second valve 256. Accordingly, the location of
boundary line 245 may be maintained within the preferred distance range away
from
rotational axis 90.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
26
In another configuration for operation, the embodiments depicted in Figures
13A, 13B and 13C can be mixed. For example, an alternative system could
provide
first valve 248 on effluent line 78 as discussed above with regard to Figure
13A and
second valve 256 on removal line 76 as discussed with regard to Figure 13C.
Second
valve 256 would be coupled with the sensor, controller and other electronics
as also
discussed with regard to Figure 13C.
Depicted in Figure 14 is a control system 295 that operates in a slightly
different way. Control system 295 includes a valve 296 coupled with effluent
line 78.
Valve 296 comprises a ball valve or other type of valve which can be fixed to
produce
1o a constant defined opening so that under normal operating procedures
exiting light
component 243 is under a first pressure. As the flow rate changes, however, it
is not
necessary for valve 296 to adjust to maintain the pressure.
Control system 295 also includes a valve 297, such as a solenoid valve, that
is
designed to selectively fully open and fully close. Valve 297 is electrically
coupled
with a sensor 298 that can be coupled with removal line 76 or effluent line
78. Valve
297 is set to fully open and close over a pressure range. For example, during
one
mode of operation valve 296 is always left open a defined amount while valve
297 is
initially closed. When the pressure sensed by sensor 298 reaches a defined
upper
limit, as a result of the heavy component collecting within vessel 60, valve
297 is
opened allowing the heavy component to exit therethrough. Valve 297 remains
open
until the pressure sensed by sensor 298 drops to a lower limit at which time
valve 297
is closed and the process is repeated. By controlling valve 297 over a narrow
pressure
range, boundary line 245 remains relatively constant. In alternative
embodiments, it
is appreciated that valves 296 and 297 can be switched between lines 76 and
78.
Furthermore, valve 297 can be set to open and close over a defined time range
and/or
pressure range.
One feature of one embodiment of the present invention relating to control of
the liquid-liquid separation system is the ability to separate immiscible
liquids that
have a specific gravity difference of less than about 5% of each other. The
present
invention is useful for separating immiscible liquids that have a specific
gravity
difference in a range from about 5% to about 0.5%, more preferably from about
4% to
about 0.5%, and most preferably from about 3% to about 0.5%. Of course, the
present invention is useful for separating immiscible liquids that have a
specific
gravity difference greater than 5%. Where a given liquid-liquid system is
provided
such that the specific gravities of the two liquids are known, control of such
systems
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
27
is achieved by the present invention. Calibration may be conducted for a given
rotating pressurized vessel as disclosed herein. A first rpm may be
established and
various pressure differences noted for different ratios of the two liquids. A
curve may
be fitted to these data. Similarly, other rpm amounts may be tested in order
to
calibrate the rotating pressure vessel. By use of standard control methods
such as a
PID controller, the rpm amount of the rotating pressure vessel may be tracked
and the
liquid-liquid system separated by maintaining the boundary layer 245 within a
desired
range.
One application of liquid-liquid separator 244 is depicted in Figure 15. Under
certain conditions, environmental discharge regulations may require water to
be
cleaned of its entrained oil to a level below about 100 ppm. According to the
embodiment of the present invention depicted in Figure 15, feed stream 12
comprises
substantially no loose particulate material except for any incidental trash
that may be
removed in trash strainer 18. Supply stream 30 enters liquid-liquid separator
244 and
the two immiscible liquids are separated as described above.
An exiting heavy component stream 250, which can comprise water in an
oil/water system, is feed to a liquid-liquid hydrocyclone 270. Hydrocyclone
270
accomplishes a separation therein that removes more of the light component
liquid
from a concentration above about 100 ppm down to a concentration of less than
about
10 ppm.
For example, where an oil/water system is provided, exiting heavy component
stream 250 comprising the water may have an oil content of about 100 ppm.
Liquid-
liquid hydrocyclone 270 provides a purified heavy component liquid stream 272
that
has an oil content in a range from about 0.1 to about 100 ppm, preferably from
about
1 to about 10 ppm, and more preferably from about 2 to about 5 ppm. A recycle
light
component liquid stream 274 is drawn off liquid-liquid hydrocyclone 276 and is
blended with flow path 20 to form supply stream 30. Typically, in a 50/50
oil/water
flow path 20, the content of water within recycle light component liquid
stream 274
will be in a range from about 50% water to about 80% water. Hydrocyclone 276
can
comprise any hydrocyclone know to those skilled in the art. One example of a
hydrocyclone is disclosed in United States Patent No. 5,133,861.
Accordingly, a method of separating a liquid-liquid mixture by use of
separator 244 depicted in Figure 11 may include one of the control systems
depicted
in Figures 13 and 14 or combination thereof and may additionally include a
hydrocyclone that is connected to the heavy component outlet.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
28
Another embodiment of the present invention is depicted in Figure 16,
wherein the more expensive sphere pressure vessel 60 has been replaced with a
double truncated cone pressure vessel 276. Figure 16 depicts extraction tubes
160
that are longer than their equivalents depicted in Figure 3. Additionally, a
flanged
edge 278 of the double truncated cone 276 is provided with a bolt 280 in order
to
assemble double truncated cone 276. A gasket or an o-ring (not pictured) may
be
placed between mating surfaces of flanged edge 278 in order to achieve a
liquid-tight
seal that holds under the pressure contemplated for the present invention.
Figure 16 also depicts the axial flow passage 174 to be more angular due to
1o the shape of double truncated cone 276. One distinction of double truncated
cone 276
is the absence of a decreasing flow slope. In other words, the flow slope
along vessel
wall 92 is constant for solid particulate matter or a heavy component liquid
as it
moves along vessel wall 92 in the direction toward radial extraction tube
opening 166.
Figure 17 is a perspective view of a separator subassembly 292 including
additional disks 202, 204 along with at least one major disk such as center
disk 170.
Figure 17 depicts a fin shape for radial fins 184 that conform with the double
truncated cone shape of pressure vessel 276. An additional distinction between
subassembly 292 and corresponding components in solid-liquid separator 10 is
that an
extraction tube 160 is disposed between each fin 184 in subassembly 292. In
this
embodiment, underflow passage 190 need not be formed between adjacent flow
channels 218. According to the present invention, double truncated cone 270
depicted
in Figures 16 and 17 may be used with either a solid-liquid separator or a
liquid-liquid
separator.
In yet another embodiment, it is envisioned that a single separator can be
configured to simultaneously separate both two or more immiscible liquids and
particulate matter from a fluid steam. The separator can be configured
substantially
identical to those disclosed in Figures 10 and 11. In this embodiment,
however, the
particulate matter collects at the farthest radial distance from the
rotational axis, the
lighter of the two immiscible liquids collects about the rotational axis, and
the heavier
of the two immiscible liquids collects between the particulate matter and the
lighter
liquid. Two separate sets of extractions tubes are used. The first set extends
down to
the particulate matter for extraction thereof. This is similar to that
previously
discussed with regard to Figure 10. The second set of extraction tubes extends
to the
heavier liquid for extraction thereof. The lighter liquid exits in the same
manner as
previously discussed with regard to Figure 11.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
29
Depicted in Figure 18 is another alternative embodiment of a separator 300
which can function as a solid-liquid separator and/or a liquid-liquid
separator.
Separator 300 comprises a frame assembly 302 which includes a horizontally
disposed base plate 304 and a spaced apart head plate 306 in substantially
parallel
alignment therewith. A cylindrical guard 308 extends between base plate 304
and
head plate 306 so as to bound a compartment 310. Base plate 304 is supported
by a
plurality of adjustable legs 312 downwardly projecting therefrom.
Attached to and extending below base plate 304 is a stationary inlet housing
314. As discussed below in greater detail, a fluid inlet line 311 and a fluid
delivery
line 313 are each fluid coupled with inlet housing 314. Fluid inlet line 311
is used to
deliver the fluid that is separated, clarified, and/or otherwise treated.
Accordingly,
depending on the configuration and intended use of separator 300, fluid inlet
line 311
can comprise flow path 20 or effluent stream 38 of Figure 1. Delivery line 313
is
used to deliver a fluid to a pressure vessel of separator 300 for use in
removing
particulate matter collected within the pressure vessel. A valve 317 is
coupled with
fluid inlet line 311 while a valve 319 is coupled with delivery line 313.
A stationary outlet housing 315 is attached to head plate 306 and upwardly
extends therefrom. Fluid coupled with outlet housing 315 is a removal line 347
and
an effluent line 348. Removal line 347 is used for the removal of solids and
heavier
fluids while effluent line 348 is used for removal of the clarified and/or
lighter fluids.
Shut off valves 349 and 351 are coupled with removal line 347 and effluent
line 348,
respectively.
Rotatably disposed within compartment 310 is a pressure vessel 316 having an
inlet end 318 and an opposing outlet end 320. As depicted in Figure 19,
pressure
vessel 316 is mounted for rotation about a rotational axis 466. Pressure
vessel 316
includes a peripheral wall 468 having an interior surface 470 bounding a
chamber
472. As previously discussed with regard to pressure vessel 60, pressure
vessel 316
and chamber 472 can have a variety of different configurations and can be made
of a
variety of different materials so as to withstand a desired internal pressure.
Although
not required, in the embodiment depicted the walls of pressure vessel 316
slope
radially outward toward an equator 474 having a maximum diameter that
encircles
rotational axis 466.
A shaft assembly 322, which is also configured to rotate about rotational axis
466, extends through and is rigidly coupled with pressure vessel 316. Shaft
assembly
322 includes an inlet end 324 that is rotatably supported within inlet housing
314.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
Shaft assembly 322 also includes an outlet end 326 that is rotatably supported
within
outlet housing 315.
Encircling shaft assembly 322 and attached to pressure vessel 316 at inlet end
318 is an annular pulley 328. Returning to Figure 18, a motor 330 is mounted
to base
5 plate 304. Motor 330 rotates a drive wheel 332 which is also disposed within
compartment 310. A belt 334 extends between drive wheel 332 and pulley 328 so
as
to facilitate rotation of pressure vessel 316 and shaft assembly 322 relative
to
stationary inlet housing 314 and stationary outlet housing 315. In this
regard, it is
appreciated that bearings are disposed between shaft assembly 322 and housings
314
1o and 315.
Depicted in Figure 20, shaft assembly 322 comprises a central manifold 336.
As depicted in Figure 22, manifold 336 comprises a substantially cylindrical
collar
337 having an interior surface 338 that extends between an inlet end 340 and
an
opposing outlet end 342. Radially inwardly projecting from interior surface
338 of
15 collar 337 is an annular flange 344. Flange 344 circles a compartment 339.
A
plurality of radially spaced apart channels 346 extend through manifold 336
and
flange 344 at the outlet side of flange 344. Each channel 346 comprises a
first
channel portion 341, a second channel portion 343, and a third channel portion
345,
each portion being concentrically disposed and consecutively constricting
toward
20 compartment 339.
An end wall 353 extends across flange 344 on the outlet side of channels 346
so as to bound one side of compartment 339. An annular mouth 355 projects from
end wall 353 and flange 344 toward outlet end 342. Extending between mouth 355
and collar 337 so as to communicate with second channel portion 343 of each
channel
25 346 is an annular slot 357.
Returning to Figure 20, shaft assembly 322 also includes a tubular input shaft
350. Input shaft 350 extends from a first end 352, which corresponds to inlet
end 324
of shaft assembly 322, to an opposing second end 354. Second end 354 is
securely
disposed within inlet end 340 of manifold 336 so as to bias against flange
344. Input
30 shaft 356 has an interior surface 360 that bounds a fluid delivery channel
362.
Delivery channel 362 extends from an inlet mouth 364 at first end 352 to
channels
346 of manifold 336. As depicted in Figure 19, inlet mouth 364 is in sealed
fluid
communication with a coupling port 365 formed on inlet housing 314. In turn,
coupling port 365 is fluid coupled with fluid delivery line 313 as previously
discussed
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
31
with regard to Figure 18. As such, fluid entering through delivery line 313
passes
through inlet housing 314 and into fluid delivery channel 362.
Returning to Figure 20, input shaft 350 comprises a tubular inner shaft 356
and a tubular outer shaft 358 encircling inner shaft 356. Inner shaft 356 and
outer
shaft 358 each extend between first end 352 and second end 354. A plurality of
radially spaced apart inlet ports 366 extend through outer shaft 358 at or
toward first
end 352. Similarly, a plurality of radially spaced apart outlet ports 368
extend
through outer shaft 358 at or toward second end 354. An extension tube 370 is
coupled with and radially outwardly projects from each outlet port 368. Formed
between inner shaft 356 and outer shaft 358 and longitudinally running from
inlet
ports 366 to outlet ports 368 is a substantially cylindrical fluid inlet
channel 372.
As depicted in Figure 19, outlet ports 368 and extension tubes 370 are
disposed within pressure vessel 316. In contrast, inlet ports 366 are in
sealed fluid
communication with a coupling port 373 formed on inlet housing 314. More
specifically, as depicted in Figure 21, inlet housing 314 bounds a cavity 374
that
encircles input shaft 350 at inlet ports 366. As such, cavity 374 is in fluid
communication with inlet ports 366. Cavity 374 has an interior sidewall 375
that
spirals so as to radially constrict.
Coupling port 373 extends into inlet housing 314 and connects with cavity 374
at an orientation tangential to cavity 374. In turn, fluid inlet line 311, as
previously
discussed with regard to Figure 18, is coupled with coupling port 373.
Accordingly,
as fluid enters through fluid inlet line 311, the fluid passes through cavity
374 and
inlet ports 366 so as to enter fluid inlet channel 372. As a result of the
tangential
orientation of coupling port 373 and the spiral configuration of cavity 374,
the fluid
entering cavity 374 is forced to rotate within annular cavity 374 about
rotational axis
466 of shaft assembly 322. The fluid is rotating in the same direction that
shaft
assembly 322 rotates. Although not required, this introduction of the fluid in
a
rotating orientation minimizes turbulent flow of the fluid passing into
separator 300,
thereby maximizing operating efficiency.
Returning to Figure 20, similar to input shaft 350, shaft assembly 322 also
includes a tubular output shaft 376. Output shaft 376 extends from a first end
378 to
an opposing second end 380. Second end 380 corresponds to outlet end 326 of
shaft
assembly 322. First end 378 is securely disposed within outlet end 342 of
manifold
336. Output shaft 376 has an interior surface 382 that bounds an effluent
channel
384. Effluent channel 384 extends from a sealed end wall 386 (Figure 22) at
first end
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
32
378 to an open exit mouth 388 at second end 380. Furthermore, a plurality of
radially
spaced apart transfer tubes 400 extend in sealed fluid communication from the
exterior of shaft assembly 322 to effluent channel 384 at first end 378.
As depicted in Figure 19, transfer tubes 400 are disposed in open fluid
communication within pressure vessel 316. In contrast, outlet mouth 388 is in
sealed
fluid communication with a coupling port 404 formed on outlet housing 315. In
turn,
coupling port 404 is fluid coupled with effluent line 348 as previously
discussed with
regard to Figure 18. As such, fluid entering effluent channel 384 through
transfer
tubes 400, exits through outlet housing 315 and effluent line 348.
Returning to Figure 20, output shaft 376 also comprises a tubular inner shaft
390 and a tubular outer shaft 392 encircling inner shaft 390. Inner shaft 390
and outer
shaft 392 each extend between first end 378 and second end 380. First end 378
of
inner shaft 390 is received within mouth 355 of manifold 336 so as to bias
against end
wall 353. An annular seal 359 extends between inner shaft 390 and mouth 355.
A plurality of radially spaced apart removal ports 394 extend through outer
shaft 392 at or toward second end 380. Formed between inner shaft 390 and
outer
shaft 392 and longitudinally running from annular slot 357 formed on manifold
336 to
removal ports 394 is an annular channel 395. Channel 395 and annular slot 357
combine to form a removal channel 396 that extends from each channel 346 on
manifold 336 to removal ports 394.
As depicted in Figure 19, removal ports 394 are in sealed fluid communication
with a coupling port 402 formed on outlet housing 315. In one embodiment,
coupling
port 402 communicates with removal ports 394 in substantially the same fashion
that
inlet ports 366 fluid couple with coupling port 373, as discussed above with
regard to
Figure 21, except that the fluid is flowing in the opposite direction.
Coupling port
402 is fluid coupled to removal line 347, as discussed with regard to Figure
18, such
that fluid and/or particulate matter entering removal channel 396 exits
through
removal ports 394, coupling port 402 and removal line 347.
Depicted in Figure 20, an extraction tube 410 is fluid coupled with and
3o radially outwardly projects from each channel 346 of manifold 336. As
depicted in
Figure 23, each extraction tube 410 comprises an outer tube 412 having an
interior
surface 414 extending between a first end 416 and an opposing second end 418.
Disposed within outer tube 412 is an inner tube 420. Inner tube 420 has an
exterior
surface 422 and an interior surface 424 each extending between a first end 426
and an
opposing second end 428. First end 426 of inner tube 420 projects past first
end 416
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
33
of outer tube 412. Interior surface of 424 of inner tube 420 bounds a supply
duct 430.
A removal duct 432 is bound between interior surface 414 of outer tube 412 and
exterior surface 422 of inner tube 420.
As depicted in Figure 22, first end 426 of inner tube 420 of each extraction
tube 410 is secured in fluid communication within third channel portion 345 of
a
corresponding channel 346 of manifold 336. As such, supply duct 430 is in
fluid
communication with compartment 339 of manifold 336 and fluid delivery channel
362. Furthermore, first end 416 of outer tube 412 of each extraction tube 410
is
secured in fluid communication within first channel portion 345 of a
corresponding
channel 346 of manifold 336. As such, each removal duct 432 is in fluid
communication with second channel portion 343 of a corresponding channel
portion
346 which in turn is in fluid communication with effluent channel 384 by way
of
annular slot 357 in manifold 336.
Returning to Figure 23, each extraction tube 410 also includes a nozzle 436.
Nozzle 436 comprises a tubular stem 438 having an interior surface 440 and an
exterior surface 442 each extending between a first end 444 and an opposing
second
end 446. Radially outwardly projecting from second end 446 of stem 438 is an
annular flange 448. Second end 428 of inner tube 420 is securely disposed
within
stem 438 while second end 418 of outer tube 412 is securely disposed about the
exterior of stem 438. A plurality of radially spaced apart slots 445 extend
through
outer tube 412 at second end 418. Slots 445 are in substantially parallel
alignment
with the rotational axis of outer tube 412. As a result, at least a portion of
each slot
445 forms a channel extending from the exterior to removal duct 432. In one
embodiment, each slot 445 is oriented so as to tangentially intersect with
removal duct
432.
An annular sidewall 450 forwardly projects from the outer edge of flange 448.
In turn, an annular lip 452 forwardly projects from the terminal end of
sidewall 450.
Secured inside of annular lip 452 so as to bias against sidewall 450 is an end
cap 454.
In this configuration, a disk shaped compartment 456 is encircled by sidewall
448 and
bounded between end cap 454 and flange 448. Compartment 456 is in fluid
communication with supply duct 430.
Depicted in Figure 24, sidewall 450 and lip 452 share a common outer face
458. Outer face 458 comprises six flat faces 460 each having a notch 462
formed
thereon. A flush port 464 linearly extends from each notch 462 to compartment
456
by passing through sidewall 450. Each flush port 464 is configured to
intersect
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
34
tangentially with interior surface 451 of sidewall 450. As a result, fluid
exiting
through flush ports 464 exits at a generally tangential orientation to a
radial are from
the center of nozzle 436. This is in contrast to the fluid exiting radially
from flush
ports 464. In view of the forgoing, fluid traveling down supply duct 430
passes
through compartment 456 and out through flush ports 464. The fluid can then
enter
removal duct 432 through slots 445.
As illustrated in Figure 22, nozzle 436 is disposed adjacent to or directly
against the interior of wall 468 of pressure vessel 316 at equator 474. As
will be
discussed below in greater detail, nozzle 436 can be further spaced radially
inward
from wall 468 but in some embodiments such positioning may be less efficient
in
removing particulate matter.
As with pressure vessel 60, pressure vessel 316 is also configured with a
plurality of fins and discs for channeling fluid through vessel 316. An
annular first
disc 478 encircles input shaft 350, and is secured, such as by pins, bolts,
welding and
the like, to inlet end 340 of manifold 336. Similarly, an annular second disc
480
encircles output shaft 376 and is secured to outlet end 342 of manifold 336.
Each of
discs 478 and 480 is positioned perpendicular to rotational axis 466.
Intersecting with discs 478 and 480 are a plurality of fins 482. As depicted
in
Figure 25, each fin 482 comprises a inside edge 484 that extends between a
first end
486 and an opposing second end 488 and a remaining perimeter edge 490. Inside
edge 484 is configured to complementary fit over manifold 336 and is
configured to
run in parallel alignment with rotational axis 466. Perimeter edge 490 is
configured
substantially complementary to interior surface 470 of pressure vessel 316.
As depicted in Figures 22 and 25, perimeter edge 490 comprises a first cut out
portion 492 at first end 486. First cut out portion 492 is formed radially out
from the
terminal end of extension tubes 370. As a result, an annular inflow equalizing
channel 494 circles shaft assembly 322 within chamber 472 and is partially
bounded
between first cutout portion 492 of each fin 482 and interior surface 470 of
pressure
vessel 316.
Perimeter edge 490 of each fin 480 also comprises a second cut out portion
496 at second end 488. Second cut out portion 496 is formed radially out from
transfer tubes 400. As a result, an annular outflow equalizing channel 498
circles
shaft assembly 322 within chamber 472 and is partially bounded by second
cutout
portion 496 of each fin 482, interior surface 470 of pressure vessel 316, and
output
shaft 376.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
Extending from inside edge 484 of each fin 482 are a pair of spaced apart disc
receive slots 500. Complementary radially spaced apart slots are also formed
on the
outside edge of discs 478 and 480 so, as depicted in Figure 26, fins 482 and
discs 478,
480 can be interlocked together by coupling the slot. This is the same form of
5 interlocking as previously discussed with regard to that fins and discs in
Figure 5.
Fins 482 are thus secured to shaft assembly 322 and extend in parallel
alignment with
rotational axis 466. Bounded between each adjacent pair of fins 482 and
extending
between inlet end 318 to outlet end 320 is a flow channel 502.
As further depicted in Figures 22 and 26, where separator 300 is primarily
to being used separate fluids of different densities, such as oil and water,
discs 478 and
480 are form with openings 504 that extend therethrough in alignment with each
fluid
channel 502. Openings 504 allow the fluid to flow through the discs as
opposing to
having to flow around them. In this embodiment, discs 478 and 480 primarily
function as supports for fins 482.
15 Depending on its intended use, the operation of separator 300 is similar to
the
operation of separator 10 and separator 244 as previously discussed. As such,
the
operating parameters previously discussed with regard to separators 10 and 244
are
also applicable to separator 300. Returning to Figure 18, during operation
motor 330
is activated causing rotation of pressure vessel 316 about rotational axis
466. Shaft
20 assembly 322, extraction tubes 410, and fins 482 with associated discs
rotate
concurrently with pressure vessel 316. A feed stream 506 is feed into
separator 300
through inlet line 311. Feed stream 506 is preferably pressurized, such as by
pump 80
in Figure 2, so that feed stream 506 is maintained under a predefined pressure
within
pressure vessel 316 during operation of separator 300.
25 With discs 478 and 480 having openings 504 therein (Figure 26), separator
300 is configured to primarily operate as a liquid-liquid separator. As such,
for
purposes of illustration feed stream 506 comprises at least two immiscible
liquids of
different density. The two liquids are again referred to as heavy component
241 and
light component 243. The operation of separator 300 will be discussed with
regard to
30 separating the two components. Although separating of the two components
can also
facilitate at least some removal of particulate matter from light component
243, a later
embodiment will be discussed with regard to operating separator 300 has a
solid-
liquid separator for removing particulate matter.
As illustrated in Figure 19, feed stream 506 passes from inlet line 311
(Figure
35 18) into coupling port 373 of inlet housing 314. As previously discussed
with regard
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
36
to Figure 21, feed stream 506 is forced to spin within cavity 374 so as to at
least being
matching the rotation of feed stream 506 with the rotation of shaft assembly
322.
Spinning feed stream 506 next passes through inlet ports 366 and into fluid
inlet
channel 372 of input shaft 350. Feed stream 506 exits inlet channel 372
through
extension tubes 370, thereby entering chamber 472 of pressure vessel 316.
Although
not required, in one embodiment the feed stream is now rotating at
substantially the
same speed as pressure vessel 316. The use of extension tubes 370 which
radially
outwardly extend from shaft assembly 322 forces inlet steam 506 exiting
therefrom to
be subject to at least a portion of the gravitational force produced by
separator 300. In
io alternative embodiments, extension tubes 370 can be removed.
As depicted in Figure 22, upon entering pressure vessel 316 the centrifugal
force imposed due to the rotation of pressure vessel 316 pushes the stream
radially
outwardly towards wall 468. As the stream enters pressure vessel 316, it
enters one of
the flow channels 502 (Figure 26) and proceeds to fill vessel 316. As
previously
discussed, flow channels 502 help to eliminate the Coriolis effect. Although
an
extension tube 370 can be provided for each discrete flow channel 502, inflow
equalizing channel 494 allows fluid communication at the entrance of flow
channels
502, thereby helping to ensure a common fluid level and flow rate through each
flow
channel 502. In alternative embodiments, inflow equalizing channel 494 can be
eliminated.
As feed stream 506 travels within flow channels 502 toward transfer tubes
400, the stream is subjected to the tremendous centrifugal forces imposed on
it due to
the rotation of vessel 316. Thus, the more dense component of the stream flows
radially outwardly while the less dense component flows radially inwardly
toward
rotational axis 466. A boundary line 508, disposed parallel to rotational axis
320, is
thus formed within chamber 472 denoting the separation between heavy component
241 and light component 243.
Light component 243 continues to travel within flow channels 502 to transfer
tubes 400. The formation of outflow equalizing channel 498 allows fluid
communication between each stream of light component 243 leaving its
corresponding flow channel 502, thereby helping to ensure a common inflow
through
each of transfer tubes 400. As a result, there can be fewer transfer tubes 400
than
flow channels 502. Alternatively, a transfer tube 400 can be provided for each
flow
channel 502, thereby eliminating the need for outflow equalizing channel 498.
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
37
Returning to Figure 19, light component 243 enters effluent channel 384
through transfer tubes 400. Lighter component 243 subsequently exits effluent
channel 384 and separator 300 through effluent line 348 (Figure 18) as either
a final
product or for subsequent processing.
Returning back to Figure 22, heavy component 241 is removed from vessel
316 by being drawn into removal duct 432 of each extraction tube 410 through
slots
445 at the end thereof. In this regard, slots 445 can be positioned at any
location
radially out from boundary line 508. Heavy component 241 travels radially
inward
along removal ducts 432 where it subsequently passes through second channel
portion
to 343 and into removal channel 396 by way of annular slot 357. In turn, heavy
component 241 exits removal channel 396 and separator 300 by way of removal
ports
394 and removal line 347. The removal of heavy component 241 and light
component 243 is controlled using one of the control systems and methods as
previously discussed with regard to Figures 13-14 so that boundary line 508 is
maintained at a desired location or within a desired range within vessel 316.
In one embodiment, it is appreciated that an extraction tube 410 can be
provided for each flow channel 502. In an alternative embodiment, an
extraction tube
410 can be provided in every other flow channel 502 or in any other desired
placement. Where an extraction tube 410 is not provided in each channel 502,
some
form of opening or gap is provided at the separating fin so that fluid
communication
of the heavy component 241 is provided between two or more flow channels 502.
Such openings or gaps can be formed by underflow passage 190 as previously
discussed.
It is appreciated that most fluids for which separation of the components is
desired will also include some form of particulate matter. The particulate
matter
which is initially suspended within feed stream 506 enters flow channels 502
where
under the gravitational force produced by separator 300 is forced to the
interior of
wall 468 primarily about equator 474. Periodically the collected particulate
matter is
removed from vessel to prevent an overbuild up within vessel 316.
By way of example, at periodic intervals valves 317 and 351 on fluid inlet
line
311 and effluent line 348, respectively, are closed. Subsequently, valves 319
and 349
on delivery line 313 and removal line 347, respectively, are opened. Next,
with vessel
316 still rotating, a cleaning stream 510 is pumped into delivery line 313.
Cleaning
stream 510 travels down delivery channel 362 where is subsequently passes into
supply duct 430 of each extraction tube 410. Finally, cleaning stream 510
passes
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
38
through flush ports 464 into chamber 472 of pressure vessel 316. As a result
of the
orientation of flush ports 464, the exiting cleaning stream 510 produces a
swirling
vortex around nozzle 436. The swirling vortex resuspends the particulate
matter that
has caked or otherwise deposited against the interior of wall 468.
Simultaneously
with delivering cleaning stream 510 into chamber 472, heavier component 241
now
having the particulate matter suspended therein is drawn out through removal
ducts
432 in extraction tubes 410 as previously discussed.
Once a desired amount particulate matter and heavy component 241 is
removed, valves 319 and 349 on delivery line 313 and removal line 347,
respectively,
are closed. Valves 317 and 351 on fluid inlet line 311 and effluent line 348,
respectively, continue to remain closed for a sufficient period of time to
enable the
resuspended solids to again settle against the interior of wall 468 as a
result of the
rotation of pressure vessel 316. Although not required, this act helps to
ensure that
resuspended solids are not dawn out with the lighter component. Once the
solids have
again settled, valves 317 and 351 are opened and the process is continued. In
yet
another method of operation, it is appreciated that feed stream 506 and
cleaning
stream 510 can feed simultaneously for concurrently removing both the heavier
component and the lighter component.
In alternative embodiments, it is appreciated that extraction tube 410 can
have
a variety of different configurations. For example, flush ports 464 can be
positioned
at any orientation including radially outward. Furthermore, flush ports 464
can be
positioned to exit through end cap 454. Any of a number of other
configurations for
nozzle 436 in which fluid can be ejected therefrom for resuspension of the
particulate
matter can also be used.
In yet another embodiment as depicted in Figure 27, an extraction tube 514 is
shown without the use of nozzle 436. Extraction tube 514 has an inner tube 516
bounding a supply duct 518 and a surrounding outer tube 520. A removal duct
522 is
bound between inner tube 516 and outer tube 520. Each of tubes 516 and 518
extends
between a first end 524 and an opposing second end 526. First end 524 of
extraction
tube 514 is coupled with manifold 316 in substantially the same way as
extraction
tube 410.
Second end 526 of each of tubes 516 and 520 are openly exposed as opposed
to being coupled with nozzle 436. As such, fluid simply exits through supply
duct
518 at second end 526 to resuspend the solids settled against pressure vessel
316
while the heavier component with the resuspended solids therein enters into
removal
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
39
duct 522 at second end 526. In this embodiment, outer tube 520 can be formed
without slots 445. If desired, however, a support collar (not shown) having
holes
extending therethrough can be positioned between inner tube 516 and outer tube
520
to maintain spacing between the tubes. It is also appreciated that the system
can be
manipulated so that cleaning stream 510 flows out of removal duct 522 into
pressure
vessel 316 while the heavy component 241 with the resuspended particulate
matter is
removed through supply duct 518.
Depicted in Figure 28 is another embodiment of an extraction tube 530.
Extraction tube 530 comprises an integral tube 532 that bounds a supply duct
534 and
an adjacently disposed removal duct 536. It is appreciated that one skilled in
the art
based on the teaching herein could modify manifold 336 to couple with a first
end of
extraction tube 530 so that supply duct 534 communicates with delivery channel
362
and removal duct 536 communicates with removal channel 396. Alternatively
extraction tube 530 can also comprise two separate tubes, one that bounds
supply duct
534 and one that bounds removal duct 536.
Further alternative embodiments of extraction tubes are disclosed in United
States Patent No. 5,853,266, entitled Fluidising Apparatus which drawings
thereof
and disclosure set forth in the Detailed Description of the Invention are
incorporated
herein by specific reference. Various forms of extraction tubes can also be
obtained
from Merpro Limited out of Nailsea, Bristol, United Kingdom.
Although the above described embodiment of separator 300 can be used for
the removal of some particulate matter, the configuration is primarily
designed for
separation of mixed liquids, i.e., separating oil and water. As previously
discussed,
however, separator 300 can also function primarily as a solid-liquid
separator. Under
this embodiment it is desirable to maximize the application of the centrifugal
force on
the particulate matter within the fluid. Accordingly, depicted in Figure 29, a
fin
assembly is shown wherein each of the fins 482 interlock with a first disc 538
and a
second disc 540 in substantially the same way that discs 478 and 480
interlocked with
fins 482 in Figure 25. One distinction between discs 538, 540 and discs 478,
480 is
that discs 538, 540 do not have large openings 504 extending therethrough. In
one
embodiment, however, one or more small gas ports 542 do extend through each of
discs 538 and 540 adjacent to their inside perimeter edge.
Turning to Figure 22, assuming that discs 478 and 480 were replaced with
discs 538 and 540, respectively, the fluid entering chamber 472 of pressure
vessel 316
through extension tubes 370 is forced to initially travel around the outer
perimeter of
CA 02474297 2004-07-22
WO 03/064053 PCT/US03/01775
40
disc 538. In so doing, the fluid and particulate matter therein are subject to
a greater
centrifugal force than if they had simply passed through openings 504. The
increased
centrifugal force results in a higher concentration of the particulate matter
settling
against interior surface 470 of pressure vessel 316 primarily about equator
474. The
5 clarified liquid is removed from pressure vessel 316 through transfer tubes
400 as
previously discussed while the solids are periodically resuspended and removed
through extraction tube 410 or the alternatives discussed therewith as also
previously
discussed. In one embodiment separator 300 can be operated using the method
and
valve assembly as discussed with regard to solid-liquid separator 10.
10 Any gas which enters vessel 316 passes through gas ports 542 and exits with
the clarified liquid. Alternatively, the gas can be removed from the feed
stream
before it enters the separator by passing the stream through a commercially
available
needle valve or other device designed to remove gases from fluid streams. In
this
embodiment, gas ports 542 are note required.
15 One of the benefits of having disc 540 solid, thereby requiring all of the
fluid
to pass around the outer perimeter thereof, is that it extends the retention
time of the
fluid within pressure vessel 316. In general, the longer the retention time
the more
particulate matter is separated from the fluid. In alternative embodiments,
however,
first disc 538 can be solid while second disc 540 can have openings 540 formed
20 therein.
The present invention may be embodied in other specific forms without
departing from its spirit or essential characteristics. The described
embodiments are
to be considered in all respects only as illustrative and not restrictive. The
scope of
the invention is, therefore, indicated by the appended claims rather than by
the
25 foregoing description. All changes which come within the meaning and range
of
equivalency of the claims are to be embraced within their scope.
