Note: Descriptions are shown in the official language in which they were submitted.
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MIXING APPARATUS WITH STATOR AND METHOD
Background
100011 Mixers (sometimes alternatively referred to as "blenders") are
generally employed to
disperse powdered chemicals into fluids. One application for mixers is in
wellbore operations,
for example, in preparing hydraulic fracturing fluid for injection into a
subterranean formation.
Generally, the fracturing fluid includes gelling agents, powders and other
granular material, e.g.,
guar gum, which are initially dispersed into the fluid via the mixer, and
subsequently hydrated,
e.g., in tanks, to result in the desired viscosity for the fluid.
[0002] Certain powder and granular material mixers include a centrifugal pump
and eductor, or a
centrifugal or high or low shear blender for dispersing the powder and
granular material into
fluid (e.g., water). Generally, the fluid is pumped by the pump into a mixing
chamber. In
eductor mixers, the mixing chamber may be proximal to a throat of a converging-
diverging
nozzle such that the eductor draws the powder into the mixing chamber by the
Venturi effect. In
blender mixers, the blender is located in the mixing chamber, and the powders
and grains are fed
thereto, e.g., by gravity. In either case, the materials, e.g., in the form of
dry powder, are
introduced to the mixing chamber, and are dispersed into the fluid. Various
devices are
employed to avoid air entrainment during the dispersion process, or entrained
air may be
removed downstream, e.g., using a hydro-cyclone or another type of air
separator. The fluid
mixture may then be sent to equipment downstream for further hydration.
100031 One challenge in dispersing powder additives such as gelling agents is
that the powders
may tend to agglomerate into clumps, sometimes referred to as "fisheyes." The
powders may
have cohesive properties, such that partially-hydrated balls fotm, e.g., with
dry powder
surrounded by a "skin" of partially-hydrated powder. This skin prevents
hydration of the dry
powder within, resulting in a stable fisheye in the fluid, rather than an even
dispersion of the
powder. As such, suboptimal mixing may result, which can affect downstream
application.
Moreover, there is an additional risk of buildup and/or clogging of the
material, e.g., in the
various throats of the system, if the materials are not sufficiently wetted at
the point of
introduction into the mixer.
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[0004] Accordingly, in some instances, a pre-wetter may be employed to
mitigate the risk of
such clumping. Pre-wetters generally provide a fluid to the powder feed,
upstream of the mixing.
However, pre-wetters require a separate pump to deliver the fluid to the
powder, upstream of the
mixing chamber. Thus, additional pumping equipment (i.e., centrifugal pumps to
provide fluid to
pre-wetter) may complicate the overall system, adding costs, maintenance, and
failure points.
Moreover, the different pieces of equipment may limit the range of flowrates
achievable for the
system, limiting the applications for which a single size or configuration of
mixer is suitable.
Summary
[0005] Embodiments of the disclosure may provide a mixer that includes an
impeller, a slinger,
and a flush line. The impeller and slinger may be disposed in a back-to-back
arrangement as part
of an impeller/slinger assembly, and may be rotated via a connection with a
shaft. The impeller
draws fluid into the mixing chamber via a fluid inlet, pressurizes the fluid,
and expels the fluid
downward and outward. The fluid is then turned toward the slinger. The slinger
may, through an
additive inlet, receive additives that are to be mixed into the fluid, and may
propel the additives
radially outward, so as to mix the additives with the fluid.
[0006] The flush line may include an opening in the mixing chamber at a
relatively high-pressure
region of the mixing chamber, for example, near the impeller. The relatively
high-pressure
region may also be an area of relatively clean fluid (e.g., low concentration
of additives) that
may be tapped by the flush line. The flush line may extend to an additive-
channeling structure
(e.g., a cone or other type of hopper) through which the additives are
received into the additive
inlet. Using the pressure of the fluid in the mixing chamber, as provided by
the impeller, the
flush line may channel the relatively clean fluid from the mixing chamber to
the additive-
channeling structure, so as to pre-wet the additive, thereby reducing the
potential for clumping.
[0006a] Some embodiments disclosed herein provide a mixer, comprising: a shaft
for driving the
mixer, the shaft disposed within and extending through a housing, the housing
comprising a fluid
inlet adjacent one axial end of the shaft, an additive inlet adjacent an
opposite axial end of the
shaft, and a tangential outlet intermediate the fluid inlet and the additive
inlet, the housing
defining a mixing chamber in fluid communication with the fluid inlet, the
additive inlet, and the
outlet; an impeller disposed on the shaft in the mixing chamber, wherein, when
rotated, the
impeller draws fluid through the fluid inlet in an axial direction; a slinger
disposed on the shaft in
the mixing chamber and configured to receive the fluid from the impeller and
to receive an
additive from the additive inlet in an axial direction opposite the axial
direction of the fluid,
Date Recue/Date Received 2023-04-03
81798931
2a
wherein, when rotated, the slinger slings the fluid and the additive radially
outwards toward the
tangential outlet of the housing; and a shearing ring stator disposed at least
partially around the
slinger, the stator comprising first and second annular portions stacked
together and vanes spaced
circiimferenfially apart so as to define flowpaths therebetween; wherein the
housing, the impeller,
the slinger and the stator are configured to prevent air received through the
additive inlet from
entrainment in the fluid received from the impeller.
10006b1 Some embodiments disclosed herein provide a mixer, comprising: a
housing defining a
mixing chamber and comprising an upper portion defining an additive inlet on
an upper end thereof
and a lower portion defining a fluid inlet on a lower end thereof, the housing
further defining a
tangential outlet intermediate the additive inlet and the fluid inlet; an
impeller/slinger assembly
comprising an impeller and a slinger disposed in the mixing chamber in a back-
to-back
configuration, wherein the impeller is configured to pump fluid in an upward
lateral direction
through the fluid inlet, and the slinger is configured to receive an additive
in a downward lateral
direction, opposite the upward lateral direction, through the additive inlet
and to sling the additive
and the fluid radially outward toward the tangential outlet; a shaft coupled
with the impeller/slinger
assembly, to drive the impeller/slinger assembly; and a shearing ring stator
disposed radially
outwards from at least a portion of the slinger, wherein the stator comprises
a first annular portion
defining a first flowpath and a second annular portion comprising a plurality
of vanes that are
spaced circumferentially apart so as to define a second flowpath therebetween,
an area of the first
flowpath being greater than an area of the second flowpath, wherein the second
annular portion is
disposed between the first annular portion and the impeller as proceeding
along the shaft, wherein
the housing, the impeller, the slinger and the stator are configured to create
a fluid-air boundary
within the housing, thereby preventing air received through the additive inlet
from entrainment in
the fluid received from the impeller.
100071 While the foregoing summary introduces one or more aspects of the
disclosure, these and
other aspects will be understood in greater detail with reference to the
following drawings and
detailed description. Accordingly, this summary is not intended to be limiting
on the disclosure.
Date Regue/Date Received 2022-08-08
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Brief Description of the Drawings
[0008] The accompanying drawings, which are incorporated in and constitute a
part of this
specification, illustrate an embodiment of the present teachings and together
with the description,
serve to explain the principles of the present teachings. In the figures:
[0009] Figure 1 illustrates a schematic view of a mixing system, according to
an embodiment.
[0010] Figure 2 illustrates an exploded, perspective view of the mixer,
according to an
embodiment.
[0011] Figure 3 illustrates an enlarged view of a portion of the stator of the
mixer illustrated in
Figure 2, according to an embodiment.
[0012] Figure 4 illustrates a perspective view of a section of the mixer,
according to an
embodiment.
[0013] Figure 5 illustrates a side, cross-sectional view of the mixer,
according to an embodiment.
[0014] Figure 6 illustrates a side schematic view of the mixer, according to
an embodiment.
[0015] Figure 7 illustrates a plot of pressure and cleanliness of the fluid
versus radius, according
to an embodiment.
[0016] Figure 8 illustrates a perspective view of an impeller/slinger assembly
of the mixer,
according to an embodiment.
[0017] Figure 9 illustrates another perspective view of the impeller/slinger
assembly, according
to an embodiment.
[0018] Figure 10 illustrates a perspective view of a slinger of the mixer,
according to an
embodiment.
[0019] Figure 11 illustrates a perspective view of a stator of the mixer,
according to an
embodiment.
[0020] Figure 12 illustrates a side, cross-sectional view of another
embodiment of the mixer.
[0021] Figure 13 illustrates a flowchart of a method for dispersing an
additive in a fluid,
according to an embodiment.
[0022] It should be noted that some details of the figures have been
simplified and are drawn to
facilitate understanding of the embodiments rather than to maintain strict
structural accuracy,
detail, and scale.
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Detailed Description
[0023] Reference will now be made in detail to embodiments of the present
disclosure, examples
of which are illustrated in the accompanying drawings. In the drawings and the
following
description, like reference numerals are used to designate like elements,
where convenient. It will
be appreciated that the following description is not intended to exhaustively
show all examples,
but is merely exemplary.
[0024] Figure 1 illustrates a schematic view of a mixing system 100, according
to an
embodiment. The mixing system 100 may generally include a process fluid source
102, a mixer
104, and downstream equipment 106, among other potential components. The
process fluid
source 102 may be or include a tank of water, a water-based solution of a
suitable pH and/or any
other type of solution, or any substantially liquid substance. Further, the
source 102 may include
or be coupled with one or more pumps for delivery of the fluid to the mixer
104; however, in
other embodiments, such pumps may be omitted with the mixer 104 providing the
pumping, for
example. The downstream equipment 106 may include any number of hydrating
tanks,
separators, other mixers/mixing systems, pumps, etc., so as to convert a
slurry exiting the mixer
104 into a desired viscosity and/or composition fluid.
[0025] As schematically depicted, the mixer 104 may include a housing 107 as
well as a fluid
inlet 108 and an additive inlet 110 extending through the housing 107. The
fluid inlet 108 may
be coupled with the fluid source 102 and may be configured to receive fluid
(i.e., the process
fluid) therefrom. The additive inlet 110 may generally include an additive-
receiving structure
111, which may be or include a cone, chamber, bowl, hopper, or the like,
having an inner surface
115 configured to receive an additive 113, which may be a dry powder, and
direct it into the
housing 107, e.g. via gravity feed.
[0026] It will be appreciated that any dry, partially dry, crystalized,
slurry, fluid, or pelletized,
and/or packaged additive may be dispersed or otherwise mixed into the fluid
using the mixer 104
via the additive inlet 110, as schematically depicted. Further, as will be
described in greater
detail below, additives received through the additive inlet 110 may be pre-
wetted into a partial
slurry, e.g., to avoid fisheyes and/or any material buildup. In particular, in
various embodiments,
the mixer 104 may be configured for use in mixing sand, guar, other powders,
etc. with the fluid.
Further, in some cases, the mixer 104 may be configured for use as a
macerator, which may tear
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apart fibers, pouches containing powders, pellets, etc. for dispersion of its
contents into the fluid.
In at least one case, the mixer 104 may be configured for use in creating gel
for use in fracturing
operations, e.g., in a wellbore; however, the mixer 104 may be employed for
any number of
different uses, consistent with the present disclosure.
[0027] The mixer 104 may also include an impeller/slinger assembly 112, which
may be driven
by a shaft 114. The housing 107 may define a mixing chamber 118 therein that
is in
communication with the inlets 108, 110. The impeller/slinger assembly 112 may
be disposed in
the mixing chamber 118. Rotation of the impeller/slinger assembly 112 may pump
the fluid
from the source 102 through the mixing chamber 118 and into the outlet 121.
[0028] As shown, the shaft 114 may extend upwards, through the inlet 110 and
out of the
additive-receiving structure 111; however, this is but one example among many
contemplated.
In another example, the impeller/slinger assembly 112 may extend downward
through the
bottom of the housing 116, may be magnetically driven, driven internally
within the mixing
chamber 118, or may be otherwise disposed in the housing 107. The shaft 114
may be coupled
with the impeller/slinger assembly 112, such that rotation of the shaft 114
rotates the
impeller/slinger assembly 112. In various cases, the shaft 114 may be directly
coupled to the
impeller/slinger assembly 112, e.g. via a bolt; however, in other cases,
gears, linkages, other
speed-changing devices, or couplings may be employed to connect the shaft 114
to the
impeller/slinger assembly 112.
[0029] The mixer 104 may also include a stator 120, which may be in the form
of a ring, arcuate
portion, etc., which may be disposed around the impeller/stator assembly 112,
as will be
described in greater detail below. Further, the mixer 104 may include an
outlet 121 and a flush
line 122. The outlet 121 may receive a slurry formed from a combination of the
additive
received through the additive inlet 110 and the fluid received through the
fluid inlet 108. The
outlet 121 may direct the slurry to one or more conduits 124, which may carry
the fluid to the
downstream equipment 106.
[0030] The flush line 122 may communicate with an area of the mixing chamber
118 that is
proximal to the impeller/slinger assembly 112 on one end, and with the
additive-receiving
structure 111 on the other end. Accordingly, the flush line 122 may tap the
process fluid from
the mixing chamber 118 at an area of relatively high pressure and deliver it
to the inner wall of
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the additive-receiving structure 111, which may be at a reduced (e.g.,
ambient) pressure. In
addition to being at the relatively high pressure, the fluid tapped by the
flush line 122 may be
relatively "clean" (i.e., relatively low additives content, as will be
described below), so as to pre-
wet fluid to the additive-receiving structure 111 and promote the avoidance of
clumping of the
additives. In some cases, the flush line 122 may provide the pre-wetting fluid
without requiring
additional pumping devices (apart from the pumping provided by the
impeller/slinger assembly
112) or additional sources of fluid or lines from the source 102. In other
examples, booster
pumps, etc., may be provided in addition to or in lieu of tapping the fluid
from the mixing
chamber 118.
100311 Figure 2 illustrates an exploded perspective view of the mixer 104,
according to an
embodiment. As noted above, the mixer 104 may include the housing 107, which
is depicted in
Figure 2 as formed from two portions: a first or "upper" housing portion 126
and a second or
"lower" housing portion 128. The upper and lower housing portions 126, 128 may
be connected
together, e.g., via bolts, clamps, other fasteners, adhesives, welds, etc., so
as to define the mixing
chamber 118 (Figure 1) therebetween. In one specific example, the lower
housing portion 128
may define a mixing area 130, and the upper housing portion 126 may define a
mixing area 132
(shown in phantom), which may be generally aligned. The mixing areas 130, 132
may together
define the mixing chamber 118 (Figure 1), in which the impeller/slinger
assembly 112 and the
stator 120 may be disposed. The lower housing portion 128 may also include an
interior surface
139, e.g., defining the bottom of the mixing area 130. It will be appreciated
that a variety of
configurations of the housing 107, including unitary and segmented
embodiments, embodiments
with doors, etc. are contemplated.
100321 The upper housing portion 126 may be coupled with the additive-
receiving structure 111
and may provide the additive inlet 110. The lower housing portion 128 may
include the fluid
inlet 108, which may extend through the lower housing portion 128 to a
generally centrally-
disposed opening 133. In an embodiment, the opening 133 may be defined in the
interior surface
139. In addition, the outlet 121 may extend from the mixing area 130, for
example, including a
substantially tangential conduit 135 extending from an opening 137
communicating with the
mixing area 130.
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100331 Turning to the impeller/slinger assembly 112 disposed in the mixing
chamber 118, the
impeller/slinger assembly 112 may include a slinger 134 and an impeller 136.
The slinger 134
and the impeller 136 may have inlet faces 134-1, 136-1, respectively, and
backs 134-2, 136-2,
respectively. The inlet faces 134-1, 136-1 may be each be open (as shown) or
at least partially
covered by a shroud, which forms an inlet in the radial inner part of the
slinger 134 and/or
impeller 136. Moreover, the inlet faces 134-1, 136-1 may be oriented in
opposite directions, e.g.,
to receive fluid and/or dry components. The backs 134-2, 136-2 may be disposed
proximal to
one another and, e.g., coupled together, such that, for example, the impeller
136 and the slinger
134 are disposed in a "back-to-back" configuration.
100341 In an embodiment, the inlet face 134-1 of the slinger 134 may face the
additive inlet 110
(e.g., the additive-receiving structure 111), while the inlet face 136-1 of
the impeller 136 may
face the fluid inlet 108 (e.g., the opening 133), as shown. For example, the
inlet face 136-1 of
the impeller 136 may face the interior surface 139, with the opening 133,
defined on the interior
surface 139, being aligned with a radial middle of the impeller 136.
100351 Accordingly, as defined by the direction in which the inlet faces 134-
1, 136-1 are
oriented, the slinger 134 may face upwards, as shown, but in other embodiments
may face
downwards or in a lateral direction. Similarly, the impeller 136 may face
downwards, as shown,
but in other embodiments, may face upwards or in a lateral direction. Further,
the slinger 134
and the impeller 136 may each have a radius, with the radius of the slinger
134 being larger than
the radius of the impeller 136. The radii of the slinger 134 and impeller 136
may be dependent
upon one another, so as to control a position of a fluid-air boundary, as will
be described in
greater detail below.
100361 The slinger 134 may further define a saucer-shape, as shown, i.e.,
formed generally as a
flatter (or flat) middle with arcuate sides and the inlet face 134-1. In an
embodiment, the sides
may be formed, for example, similar to, or as part of a torus that extends
around the middle of
the slinger 134. In another embodiment, the slinger 134 may be bowl-shaped
(e.g., generally a
portion of a sphere). Further, the slinger 134 may include slinger blades 138
on the inlet face
134-1. The number of blades 138 may range from about two blades to about 20
blades, for
example, about nine blades. In some cases, the blades 138 may be curved
circumferentially as
proceeding radially outwards from the shaft 114, but in others the blades 138
may be straight, as
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shown. When rotated, the stinger 134 may be configured to propel fluid and/or
dry additives
received from the inlet 110 radially outwards by interaction with the blades
138 and upwards (as
shown), e.g., as influenced by the shape of the slinger 134.
[0037] Although not visible in Figure 2, the impeller 136 may also include a
plurality of blades
on the inlet face 136-1, which may be generally aligned with the opening 133.
When the shaft
114 is turned, the impeller blades may draw fluid through the opening 133 of
the fluid inlet 108,
and then expel the fluid downwards and radially outwards. As such, a region of
relative high
pressure may develop between the lower housing portion 128 and the impeller
136, which may
act to drive the fluid around the mixing chamber 118 and toward the slinger
134.
[0038] The flush line 122 may include an opening 140 defined in the lower
housing portion 128
proximal to this region of high pressure. For example, the opening 140 may be
defined in the
interior surface 139 at a position between the outer radial extent of the
impeller 136 and the
opening 133 of the inlet 110. In other embodiments, the opening 140 may be
disposed on the
interior surface 139 and radially outside of the impeller 136 and/or elsewhere
in the mixing
chamber 118. The flush line 122 may also include a conduit 142, which may be
or include one
or more pipes, tubes, hoses, flow restrictors, check valves, etc. The conduit
142 may connect
with a cone inlet 144 defined, for example, substantially tangent to the
additive-receiving
structure 111, such that fluid is transported from the opening 140 via the
conduit 142, through
the cone inlet 144, and into the additive-receiving structure 111. The fluid
may then take a
generally helical path along the interior of the additive-receiving structure
111, until it is
received through the additive inlet 110 to the slinger 134. As such, the fluid
received through the
cone inlet 144 may generally form a wall of fluid along the inner surface 115
of the additive-
receiving structure 111.
[0039] In at least one specific embodiment, a pressure gradient may develop
between the
impeller 136 and the lower housing portion 128, with the pressure in the fluid
increasing as
proceeding radially outwards from the opening 133. Another gradient, related
to the
concentration of the additives in the fluid may also develop in this region,
with the concentration
of additives increasing as proceeding radially outward. In some cases, a high
pressure head and
low concentration may be desired, so as to provide a flow of relatively clean
fluid through the
flush line 122, propelled by the impeller/slinger assembly 112. Accordingly,
the opening 140 for
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the flush line 122 may be disposed at a point along this region that realizes
an optimal tradeoff
between pressure head of the fluid and concentration of the additives in the
fluid received into
the flush line 122. Additional details regarding the tradeoff are provided
below.
[0040] Turning again to the stator 120, the stator 120 may form a shearing
ring, which may be
received around the radial outside of the impeller/slinger assembly 112 and in
the mixing
chamber 118 (Figure 1). In an example, the stator 120 may be coupled with the
upper housing
portion 126, e.g., via bolts, other fasteners, adhesives, welding, etc.
[0041] Figure 3 illustrates an enlarged sectional view of the stator 120 of
Figure 2, according to
an embodiment. Referring now to both Figures 2 and 3, as shown, the stator 120
may include
first and second annular portions 146, 148, which may be stacked together to
form the stator 120.
The stator 120 may be held generally stationary with respect to the rotatable
impeller/slinger
assembly 112, e.g., via fastening with the upper housing portion 126. In
another embodiment,
the stator 120 may be supported by the impeller/slinger assembly 112 and may
rotate therewith.
In either example, the stator 120 may ride on the inlet face 134-1 of the
slinger 134, or may be
separated therefrom.
[0042] The first annular portion 146 may be configured to minimize flow
obstruction. As
shown, in some cases, the first annular portion 146 may include a shroud 150
and posts 152
defining relatively wide slots 154, allowing relatively free flow of fluid
therethrough. In other
embodiments, the first annular portion 146 may omit the shroud 150, as will be
described in
greater detail below.
[0043] While the first annular portion 146 may minimize flow obstruction, the
second annular
portion 148 may be configured to maximize flow shear, so as to promote
turbulent mixing, and
thus may include a series of stator vanes 156 that are positioned closely
together around the
stator 120. Narrow flowpaths 158 may be defined between stator vanes 156;
however, the sum
of areas of the flowpaths 158 may be less than the sum of the areas of the
stator vanes 156. In
various embodiments, the ratio of the stator vane 156 cross-sectional area
(i.e., the area that
obstructs flow) to the area of the flowpaths 158 may be between about 1:2 and
about 4:1, for
example, about 1.5:1. Further, the area of each of the stator vanes 156 may be
greater than the
area of each of the flowpaths 158. Moreover, the stator vanes 156 may be
disposed at any pitch
angle with respect to the circumference of the stator 120. For example, the
stator vanes 156 may
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be oriented straight radial, against rotation (e.g., to increase shear), or
with rotation. In the
example illustrated in Figure 2 (and also in Figures 3 and 4, described
below), the stator vanes
156 may have a shroud 157 that separates the sections 146, 148. In other
embodiments, as will
be described in greater detail below, the statorl 20 may omit either or both
of the shrouds 150,
157.
[0044] Figure 4 illustrates a perspective view of a section of the mixer 104,
according to an
embodiment. Figure 5 illustrates a side cross-sectional view of the mixer 104,
with the flush line
122 illustrated schematically, according to an embodiment. Referring to both
Figures 4 and 5,
the shaft 114 extends through the additive inlet 110 and is coupled with the
impeller/slinger
assembly 112. The impeller 136 faces the opening 133, such that impeller
blades 160 of the
impeller 136 draw fluid through the inlet 108 via the opening 133.
[0045] With continuing reference to Figures 4 and 5, Figure 6 schematically
illustrates a
simplified view of the cross-section of the mixer 104, according to an
embodiment. As shown,
the impeller 136 may draw the fluid upward from the interior surface 139, and
then expel it
downwards (toward the interior surface 139) and radially outward. The fluid
may then move
upward in the mixing chamber 118, e.g., along an outer wall of the housing 107
to the top of the
upper housing portion 126, where it may be turned radially inwards. The fluid
may then proceed
through the first annular portion 146 of the stator 120 to the stinger 134,
and then be pushed
radially outward, as well as upward, back toward the upper housing portion
126. This may
create a turbulent churning, as well as a hydrodynamically-stable interface
between the fluid and
the air, generally manifesting as a ring-shaped air-fluid boundary or "eye"
161 (Figure 5)
between a root 138-1 and a tip 138-2 of the slinger blades 138. The slinger
134 thus tends to
create a cyclonic separation effect, whereby air received through the inlet
110 is prevented from
entrainment in the fluid received from the impeller 136.
[0046] Meanwhile, the additives 113 are poured into or otherwise received
through the inlet 110,
e.g., propelled by gravity, but may also be propelled by pressure
differentials, vacuums, blowers,
pumps, etc. The additives are then received onto the inlet face of the slinger
134, e.g., on the air
side of the air-fluid boundary. The additives collide with the blades 138 and
are slung radially
outward into the fluid received from the impeller 136, while producing a
circumferential velocity
component to the fluid and dry additives. The circumferentially- and radially-
driven dry
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additives and fluid then pass through the second annular portion 148 of the
stator 120, where the
combination is subjected to a high shear by interaction with the stator vanes
156 as it passes
through the flowpaths 158. The shearing provided by the interaction with the
blades 138 and
stator vanes 156 and the turbulent flow developed by the impeller/slinger
assembly 112 may
provide a generally uniform dispersion of the additives in the fluid from the
source 102, resulting
in a slurry.
[0047] In particular, the first section 146 of the stator 120 is disposed at a
small radial clearance
from the stinger blades 138 (e.g., radially outward therefrom) such that the
slurry mixture of
additives 113 (e.g., powdered chemicals) and fluid being slung outward by the
stinger blades 136
is sheared in a first stage in the clearance, by the relative movement of the
blades 134 and the
stator vanes 156. The slurry is then subjected to a second shear stage, as it
is squeezed between
the adjacent stator vanes 156 and pushed radially outwards through the
flowpaths 158 by the
action of the stinger 134. Moreover, the sudden expansion of the flow area
radially outside of
the stator 120 results in cavitation, further promoting mixing. As such, the
mixer 104 provides,
in operation, a two-stage, high shearing and regional cavitation mixing. The
second section 148
of the stator 120 may have a substantially larger opening and be disposed
above the stinger
blades such that it allows the fluids to enter the stinger 134 through the
slots 154, or otherwise
minimizes flow obstruction through the stator 120.
[0048] The slurry may undergo such mixing multiple times, churning back
through portions of
the stinger 134 to effect further dispersion of the additives into the fluid,
and eventually reaches
the outlet 121, as shown in Figure 5. The slurry reaching the outlet 121 is
channeled from the
mixing chamber 118, e.g., to downstream equipment 106 (Figure 1) for further
hydration,
deployment, treatment, etc. Further, as schematically depicted in Figure 5,
the mixer 104 may
also provide a self-regulating pre-wetter with the flush line 122. The opening
140 may be
disposed in the interior surface 139 of the lower housing portion 128, e.g.,
radially inside or
outside of the outer radial extent of the impeller 136. This may represent an
area of high
pressure in the mixing chamber 118, which is "clean" relative to fluid in
other parts of the
mixing chamber 118, e.g., proximal to the outlet 121 and/or in the stinger
134.
[0049] The tapped, relatively clean fluid received via the opening 140 may
flow through the
flush line 122 to the additive-receiving structure 111. The pre-wetting fluid
may then flow, e.g.,
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by gravity, along the interior surface of the additive-receiving structure 111
through the inlet 110
and back to the slinger 134. As such, the additives may be urged along the
additive-receiving
structure 111, toward the slinger 134, while being pre-wetted therein. This
may serve to
minimize clumping along the surface of the additive-receiving structure 111.
[0050] Figure 7 illustrates a plot of pressure and cleanliness in the fluid in
the mixing chamber
118 versus the radius from the center of the opening 133, which is aligned
with the center of the
impeller 136. As shown, proceeding radially outward with respect to the
impeller 136, the
pressure may move from ambient (i.e., zero psig) to a maximum pumping pressure
provided by
the impeller 136. The relationship between radial position and pressure head
may be generally
exponential, until the position reaches the radial extent of the impeller 136.
[0051] Conversely, the "cleanliness," that is, the inverse of the
concentration of additives in the
fluid, or, stated otherwise, the purity of the fluid, may decrease proceeding
radially outward, as
the fluid received through the inlet 108 is mixed with the additives.
Accordingly, a tapping
region 141 may be calculated, providing the optimal tradeoff between pressure
head and
cleanliness in the fluid tapped by the flush line 122 via the opening 140.
[0052] Moreover, the flowrate of the relatively clean fluid through the flush
line 122 may be
controlled, for example, by matching a location or size of the opening 140,
the conduit 142,
and/or the cone inlet 144 to the pressure head developed by the impeller 136.
With a known
pressure drop through the flush line 122, such control may result in an
optimized amount of fluid
flowing through the flush line 122. Further, the flush line 122 may include
one or more flow
control devices, which may further allow for adjustment of the flowrate
through the flush line
122.
[0053] Figure 8 illustrates a perspective view of the impeller/slinger
assembly 112 and the stator
120, according to an embodiment. The stator 120 may include the first and
second annular
portions 146, 148, as described above. However, the second annular portion 148
may include a
plurality of posts 170, which may extend upwards from the first annular
portion 146, but may not
include a shroud. For example, the posts 170 may be coupled to the upper
housing portion 126
(Figure 2). The posts 170 may be any shape, including cylindrical, aerofoils,
etc. and may be
spaced apart so as to define wide channels therebetween. Accordingly, the
second annular
portion 148 may be configured to minimize flow obstruction therethrough.
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100541 Moreover, as shown, the stator vanes 156 may be pitched at an angle
relative to the
circumference of the stator 120, for example, opposite to rotation, so as to
maximize shearing.
Similarly, the slinger blades 138 may be curved circumferentially, e.g., to
facilitate slinging the
fluid and additives radially outwardly, and with a circumferential velocity
component, so as to
produce the shearing.
00551 The stator 120 illustrated in Figure 8 may act as a diffuser. In at
least one embodiment,
the stator vanes 156, as illustrated, may be oriented to recover pressure
and/or may facilitate air
introduction into the slurry, for example, in foaming operations.
00561 Figure 9 illustrates another perspective view of the impeller/slinger
assembly 112,
illustrating the inlet face 136-1 of the impeller 136, according to an
embodiment. As shown, the
blades 160 of the impeller 136, which may be curved, straight, or any other
suitable geometry,
may draw fluid upwards, and then expel it radially outwards into the mixing
chamber 118 (e.g.,
Figure 3). It will be appreciated that the impeller 136 may be configured for
high-speed (e.g.,
between about 300 rpm and about 20,000 rpm) use, and may be capable of pumping
of
producing between about 5 psi (about 34 kPa) and about 150 psi (about 1000
kPa), e.g., about 60
psi (about 414 kPa) of head.
00571 Figure 10 illustrates a perspective view of another slinger 200 of the
mixer 104,
according to an embodiment. In some cases, rotor blades (such as blades 138 as
shown in Figure
1) may achieve dispersion that exceeds desired rates, e.g., with engineered
particles such as
encapsulated breakers. This may cause, in some cases, premature release of
chemicals in the
fluid. Accordingly, in an embodiment, the slinger 200 may provide a low shear
or controlled
shear dispersion that can handle such delicate chemicals, which are prone to
damage or
otherwise unsuitable for use in the more-aggressive slinger embodiments. In
particular, the
slinger 200 may effect a relatively gradual dispersion using generally
concentric, annular disks
202, which are stacked one on top of the other upward from a hub 204. The
annular disk 202-1
closest to the hub 204 may have a smaller inner diameter than the annular disk
202-2 adjacent
thereto, which in turn may have a smaller inner diameter than the annular disk
202-3. This may
repeat as proceeding between adjacent disks 202 away from the hub 204, so as
to provide an inlet
face 205 for the stinger 200 through which fluid and/or additives may be
received and propelled
outwards. It will be appreciated that any number of annular disks 202 may be
included.
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100581 In an embodiment, the disks 202 may be held apart by vanes 206,
providing narrow
flowpaths between the disks 202. The vanes 206 may provide slots, one for each
of the annular
disks 202, into which the annular disks 202 may be received and coupled to the
vanes 206.
Accordingly, the narrow paths may extend radially outwards, for example,
obstructed in the
radial direction only by the narrow vanes 206. In other embodiments, separate
vanes may extend
between each pair of adjacent disks 202, rather than or in addition to the
vanes 206 that extend
through the entire set of disks 202. Moreover, in some embodiments, the vanes
206 may couple
with one or more subsets of the total number of disks 202. In some cases, the
vanes 206 may be
omitted, with the disks 202 held together in a spaced-apart relation in any
other suitable manner.
100591 The large surface area of the annular disks 202 bordering the
flowpaths, and the
narrowness of the flowpaths, may result in shearing and turbulent flow of the
fluid therethrough.
Such shearing may have a similar effect as the slinger 134 and stator 120
discussed above, and
may promote dispersion of dry additives into fluid being slung radially
outwards therethrough,
while minimizing the impact forces from the vanes 204 which may damage more
delicate
material. In some cases, the shearing provided by the slinger 200 may result
in the stator 120
being omitted; however, in other cases, the shearing effects of the stator 120
and the slinger 200
may be combined.
100601 Figure 11 illustrates a perspective view of a shroudless stator 300,
according to an
embodiment. As shown, the stator 300 includes first and second annular
portions 302, 304,
which may, as shown, both be shroudless. The first annular portion 302 may
include a base 306
and a series of vanes 308 extending upwards from the base 306 and disposed at
intervals around
the first annular portion 302. Flowpaths 310 are defined between adjacent
vanes 308.
100611 With the stator 300 being shroudless, the top of the flowpaths 310 may
be open-ended,
opening into the second annular portion 304 of the stator 120. The second
annular portion 304
may include tabs 312 extending upwards from the first annular portion 302. The
tabs 312 may
be thicker, circumferentially, than the vanes 308, for example, each spanning
two vanes 308 and
one of the flowpaths 310; however, any relative sizing of the vanes 308 and
tabs 312 may be
employed. The shroudless configuration may minimize obstruction of the flow
from the impeller
136, increasing efficiency of the mixer 104.
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[0062] Figure 12 illustrates a side, cross-sectional view of the mixer 104,
according to another
embodiment. The embodiment shown in Figure 12 may be generally similar to the
embodiment
of the mixer 104 shown in one or more of Figures 1-8, with similar components
being referred to
using like numerals and duplicative description being omitted herein. The
mixer 104 shown in
Figure 12 may, however, have a stator 400 that is integrated with the housing
107, for example,
with the lower housing portion 128. Accordingly, the stator 400 may be spaced
radially apart
from and may circumscribe the impeller/slinger assembly 112, with the outlet
121 being
disposed radially outward of the stator 400. Supporting (and/or integrating)
the stator 400 by the
lower housing portion 128 may facilitate low friction rotation of the
impeller/slinger assembly
112, since the stator 400 and the impeller/slinger assembly 112 may not be in
contact with one
another. In another embodiment, the stator 400 may be suspended from and/or
integrated with
the upper housing portion 126 to similar effect.
[0063] This embodiment of the mixer 104 may, in some cases, ensure all or
substantially all of
the incoming fluid is mixed with the additive chemical before exiting the
mixer 104. For
example, in cement mixing, the mixer 104 may blend the powder uniformly, so as
to avoid
relying on the pipe turbulence downstream of the mixer 104 to effect such
mixing.
[0064] As with the stator 120, the stator 400 may be shrouded or shroudless,
and may include
two or more annular portions (e.g., one for low flow disruption and one for
high flow disruption).
The stator 400 may, however, be configured to receive substantially all fluid
flow out of the
volume of fluid, which may enhance bulk mixing. Such a mixer 104 embodiment
employing the
stator 400 may be suited for powder dispersion into a very viscous fluid
medium as well as when
powder volume fraction in the mixture is high, e.g., with cement mixing.
Additionally, although
not shown, embodiments of the mixer 104 shown in Figure 12 may include a flush
line 122, e.g.,
as described above.
[0065] Figure 13 illustrates a flowchart of a method 1000 for dispersing an
additive, such as a
dry additive (e.g., powder, granules, etc.) into a fluid, according to an
embodiment. The method
1000 may proceed by operation of one or more embodiments of the mixing system
100 and/or
the mixer 104 and, thus, is described herein with reference thereto. However,
it will be
appreciated that the method 1000 is not limited to any particular structure,
unless otherwise
expressly stated herein.
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[0066] The method 1000 may include feeding a fluid into the mixing chamber 118
of the mixer
104 through the fluid inlet 108, as at 1002. For example, the mixing chamber
118 may be
defined within the housing 107, which may define the fluid inlet 108 that
receives the fluid from
the source 102. The method 1000 may also include feeding the additive into the
mixing chamber
118 through the additive inlet 110, as at 1004. The feeding at 1004 may be
propelled by gravity,
for example, by pouring the additive into the additive-receiving structure 111
of the additive inlet
110, although other methods for feeding the additive are also contemplated.
[0067] The method 1000 may also include rotating the impeller/slinger assembly
112 disposed in
the mixing chamber 118, as at 1006. Rotating the impeller/slinger assembly 112
may draw fluid
from the fluid inlet 108 (e.g., upwards) and radially outward, for example, by
action of the
impeller 136 disposed with its inlet face 136-1 proximal to the interior
surface 139. Rotating the
impeller/slinger assembly 112 may further cause the fluid, e.g., received from
the impeller 136,
along with the additive received through the additive inlet 110, to be slung
radially outward. In
an example, the outward slinging may be caused by the slinger 134 of the
impeller/slinger
assembly 112, which may include blades 138 and/or disks 202. Further, the
slinger 134 may
include an inlet face 134-1, which may, for example, be oriented toward the
additive inlet 110.
When the additive is fed through the additive inlet 110, the additive may
impinge on the blades
138 and/or disks 202 and be slug radially outward
[0068] The combination of the impeller 136 and the slinger 134, e.g., in a
back-to-back
configuration, may result in an eye defined by a hydrodynamically-stable fluid-
air boundary, to
develop in the slinger 134. For example, the boundary may be present radially
between a hub
138-1 and tip 138-2 of the blades 138 of the slinger 134. The slinging of the
additive (as well as
the fluid received from the impeller 136) radially outwards by action of the
slinger 134 may
result in the additive crossing the air-fluid boundary, and thus being at
least partially dispersed
into the fluid, thereby forming a slurry. In some cases, the action of the
impeller/slinger
assembly 112 may create a hydrodynamically-stable eye, forming a fluid-air
boundary, thereby
preventing air from becoming entrained in the fluid. However, in some cases,
air may be
purposely introduced into the mixture, for example, in foaming applications,
e.g., using the stator
120 of Figure 8.
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100691 The additive may further be dispersed in the fluid, promoting increased
homogenization
of the slurry, by the slurry being received through the stator 120, as at
1008. Various
embodiments of the stator 120 are discussed above, e.g., with the first and
second annular
portions 146, 148 provided to minimize and maximize fluid shearing,
respectively. In general,
the stator 120 may include the plurality of vanes 156, defining flowpaths
therebetween, through
which the slurry is received. The interaction of the swirled, turbulent flow
of the slurry with the
stator vanes 156 may result in increased shearing of the fluid, which may
increase mixing
efficiency of the mixer 104. Once mixed to a desired degree, the slurry with a
certain
concentration of additives may be expelled from the mixer 104, as at 1010, via
the outlet 121,
which may be disposed radially outwards of the impeller/slinger assembly 112.
100701 The method 1000 may also include, e.g., as caused by rotation of the
impeller/slinger
assembly 112 at 1006, a portion of the fluid or slurry (e.g., with a
relatively low concentration,
relative to flow through the outlet 121) to flow into the flush line 122 and
to the additive inlet
110, to pre-wet the additive, as at 1012. For example, the flush line 122 may
include the opening
140, which may be positioned and/or sized so as to receive a slurry with a
predetermined (e.g.,
minimized) concentration of additives at a predetermined (e.g., maximized)
pressure in the
mixing chamber 118. The sizing of the flush line 122, placement of the opening
140 thereof,
and/or employment of flow control devices in the flush line 122, etc. may
allow control of the
amount of fluid that proceeds through the flush line 122 and the composition
thereof.
100711 It will be appreciated that terms implying a direction or an
orientation, e.g., "up,"
"down," "upwards," "downwards," "above", "below," "laterally," and the like
are employed
merely for convenience to indicate relative positioning of the components with
respect to each
other, as depicted in the various figures. One of ordinary skill in the art
will appreciate that these
terms are not intended to limit the mixer 104 to any particular orientation,
however.
100721 Further, while the present teachings have been illustrated with respect
to one or more
embodiments, alterations and/or modifications may be made to the illustrated
examples without
departing from the spirit and scope of the appended claims. In addition, while
a particular feature
of the present teachings may have been disclosed with respect to only one of
several
implementations, such feature may be combined with one or more other features
of the other
implementations as may be desired and advantageous for any given or particular
function.
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Furthermore, to the extent that the terms "including," "includes," "having,"
"has," "with," or
variants thereof are used in either the detailed description and the claims,
such terms are intended
to be inclusive in a manner similar to the term "comprising." Further, in the
discussion and
claims herein, the term "about" indicates that the value listed may be
somewhat altered, as long
as the alteration does not result in nonconformance of the process or
structure to the illustrated
embodiment. Finally, "exemplary" indicates the description is used as an
example, rather than
implying that it is an ideal.
100731 Other embodiments of the present teachings will be apparent to those
skilled in the art
from consideration of the specification and practice of the present teachings
disclosed herein. It
is intended that the specification and examples be considered as exemplary
only, with a true
scope and spirit of the present teachings being indicated by the following
claims.
