Note: Descriptions are shown in the official language in which they were submitted.
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SPLIT-VANE BLENDER METHOD AND APPARATUS
Background and Field
This invention relates to blenders as well as pumping
apparatus; and more particularly relates to a novel and improved
method and apparatus for blending liquids with solid particulate
materials, and still further relates to a novel and improved
impeller assembly which is conformable for use with blenders as
well as centrifugal pumps.
Numerous types of blenders have been devised for
intermixing and pumping large volumes of liquid/solid slurries.
For example, downhole operations in oil and gas fields, such as,
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fracturing and cementing operations utilize a blender in which
liquids and solids are introduced into a housing, a rotor within
the housing, upper and lower impeller portions for intermixing the
materials and throwing or advancing the materials outwardly into an
annulus surrounding the rotor from which the resultant intermixture
or slurry can be discharged into the well.
A representative
blender is that set forth and described in U.S. Patent No.
5,904,419 to Jorge 0. Arribau, one of the inventors of this
invention which patent is incorporated by reference herein
(hereinafter referred to as the '419 patent). Other representative
patents are U.S. Patent Nos. 4,239,396 to Arribau; 3,256,181 and
3,326,536 to Zingg; 4,850,702 to Arribau and 4,460,276 to Arribau.
In the '419 patent, liquids were introduced through
mixing apertures intermediately between the rotor and annulus for
mixing with the solid particles prior to introduction into the
relatively high pressure annulus.
There is a continuing but unmet need for a blender of
simplified construction which can regulate the balance or mixing
point between the solids and slurry in a region radially outwardly
of the eye and be capable of pumping the slurry under a
substantially constant pressure over a wide range of mass flow
rates. There is similarly a need for an impeller assembly in which
impeller vanes are designed to regulate the slurry pressure as well
as to prevent liquid or slurry leakage back into the eye or central
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expeller area.
Still further, to decrease the depth of vanes
required for the upper impeller region by encouraging more
immediate outward flow of sand to achieve the same capacity or mass
flow rate as deeper vanes.
Summary
It is therefore an object to provide for a novel and
improved method and apparatus for blending liquids and solid
particles by counterflow of the liquid with respect to the
direction of solid flow through an impeller region and establish a
balance point between the liquid and solid particle intermixture in
an impeller for a blender as well as the pressure/velocity ratio of
liquid/solid flow by regulating the size, length and configuration
of the impeller vanes; also, to prevent backflow of liquids or
solid particles around impeller zones of a blender apparatus by
maintaining substantially constant pressure of a liquid/solid
slurry over a wide range of mass flow rates.
In apparatus for blending liquids with solid particles in
which a housing has an upper solid particle inlet and lower liquid
inlet, a center drive shaft in the housing and an outlet
communicating with an annular space in outer spaced surrounding
relation to the drive shaft; upper impeller vanes are mounted for
rotation on the shaft whereby to direct solid particles from the
inlet toward the annular space; lower impeller vanes are mounted
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for rotation on the drive shaft whereby to direct liquid from the
liquid inlet through the annular space to intermix by counterflow
of the liquid with the solid particles; and a divider plate is
interposed between the upper and lower impeller vanes. In one
form, the upper impeller includes inner and outer concentric vanes,
the inner vanes being operative to force the solid particles into
the outer impeller vane region at a rate sufficient to
substantially reduce the height of the outer vanes necessary to
intermix the desired ratio of solid particles to liquids and
prevent any tendency of the solid particles to back up into the
center inlet region. In another form, the radial tips of the upper
impeller vanes are lengthened to discourage return flow of the
liquids or slurries toward the center of the impeller region. In
another embodiment, the upper impeller is characterized by having a
series of circumferentially spaced, generally V-shaped vanes in
which the trailing side of each vane will prevent return flow of
the liquid or liquid/solid mixture toward the inner radial area and
particularly the eye of the impeller. Further, a lower impeller
has circumferentially spaced, curved vanes with outer radial split
tip end portions, the leading tip end portion discouraging reverse
flow of the water into the next pocket between the vanes.
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In another embodiment, there is provided in apparatus for blending a liquid
with solid
particles within a housing which has an upper solid particle inlet and a lower
liquid inlet, a
center drive shaft extending between said inlets, and an outlet in
communication with an
annular space in outer spaced surrounding relation to said drive shaft, the
improvement
comprising: a divider plate mounted for rotation on said drive shaft; an upper
impeller
including a plurality of split, circumferentially spaced vanes extending
upwardly from an
upper surface of said divider plate, said vanes being of generally V-shaped
configuration and
split into a first radially extending side and a second side diverging
radially outwardly at an
acute angle away from first radially extending side wherein at least one of
said sides extends
from an inner radial edge of said divider plates; and a lower impeller
including a series of
circumferentially spaced lower vanes extending downwardly from an underside of
said
divider plate.
In another embodiment, there is provided in apparatus for blending a liquid
with solid
particles, said apparatus comprising a housing which has an upper solid
particle inlet and a
lower liquid inlet, a central drive shaft extending between said inlets, and
an outlet in
communication with an annular space in outer spaced surrounding relation to
said drive shaft,
the improvement comprising: a divider plate mounted for rotation on said drive
shaft having a
plurality of inner concentric expeller vanes and an upper impeller in outer
concentric relation
to said inner concentric expeller vanes; said upper impeller including a
plurality of
circumferentially spaced, split vanes extending upwardly from an upper surface
of said
divider plate, each of said split vanes being of generally V-shaped
configuration having a
first radially extending side and a second side diverging at an angle away
from said radial
side, each of said split vanes provided with a recess between said sides; a
lower impeller
including a series of circumferentially spaced, curved vanes extending
downwardly from an
underside of said divider plate; and means for pumping liquid into said lower
liquid inlet for
intermixture with materials introduced through said upper solid particle inlet
including a
booster pump for maintaining a minimum pressure head between said inlet and
outlet.
In another embodiment, there is provided in apparatus for blending a liquid
with solid
particles within a housing which has an upper solid particle inlet and a lower
liquid inlet and
a central drive shaft extending between said inlets, the improvement
comprising an outer
concentric impeller and an inner concentric, an expeller assembly including a
mounting plate
mounted on said central drive shaft having a plurality of alternating, longer
vanes on said
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mounting plate extending radially from said drive shaft and substantially
shorter vanes
extending radially inwardly from an outer edge of said mounting plate.
In addition to the articles of manufacture described above, further aspects
and
embodiments will become apparent by reference to the drawings and by study of
the
following
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descriptions. Exemplary embodiments are illustrated in reference
to Figures of the drawings. It is intended that the embodiments
and Figures disclosed herein are to be considered illustrative
rather than limiting.
Brief Description of the Drawings
Figure 1 is a somewhat fragmentary view of one form of
blender apparatus mounted on a truck;
Figure 2 is a longitudinal sectional view of a modified
form of blender utilized in combination with a booster pump;
Figure 3 is a top plan view with a portion of the top
cover broken away of the form of blender shown in Figures 1 and 2;
Figure 4 is a top plan view in detail of the top cover
plate and inner concentric expeller vanes of the blender shown in
Figures 1 and 2;
Figure 5 is a top plan view in detail of the upper
impeller vanes and inner concentric expeller vanes of the form of
blender shown in Figures 1 and 2;
Figure 6 is an elevational view in detail of the inner
concentric expeller vanes shown in Figures 2 and 4;
Figure 7 is a bottom plan view of the lower impeller
vanes of the form of blender shown in Figures 1 and 2;
Figure 8 is a bottom plan view of the bottom cover plate
in the form of blender shown in Figures 1 and 2;
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Figure 9 is a top plan view of modified upper impeller
vanes; and
Figure 10 is a bottom plan view of a modified form of
lower impeller vanes.
Detailed Description of One Embodiment
Referring in more detail to the drawings, one form of
blender apparatus is illustrated in Figures 1 to 7, and Figure 1
illustrates a typical mounting of a blender unit 10 on a truck T.
The blender unit 10 is illustrated in more detail in Figure 2 and
includes a booster pump P communicating through line L2 to the
intake port 16 of the unit. Referring to Figures 1 and 2, in oil
and gas operations, such as, fracturing or cementing wells, the
unit 10 is mounted on a truck bed B including an engine E with a
drive mechanism D to impart rotation via speed reducer mechanism M
to a central drive shaft 12. The solid particulate matter, such
as, sand is delivered from a storage area S by means of an auger
system represented at A to the upper end of a hopper 14. There,
the sand is permitted to advance by gravity into the apparatus 10.
The sand is thoroughly mixed with a liquid which is introduced
through the inlet line L2 and the booster pump P into the inlet
port 16; and the resultant slurry is discharged via outlet port 18
through a delivery line L1 under sufficient pressure to be
delivered to other trucks for delivery to a well head. The booster
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pump P regulates the pressure in the annulus of the impeller
assembly and can be closely controlled to maintain a constant
suction or pressure head from the outlet of the pump P to the inlet
port 16 as well as to increase the pressure as desired.
The
booster pump P also can be run backwards to reduce the pressure or
to maintain optimum pressure. For the purpose of illustration but
not limitation, one suitable type of booster pump which can be
utilized for this purpose is the Model AP/MPAF manufactured and
sold by Goulds Pumps of Seneca, New York.
The speed reducer M, as shown in Figure 2, is a right
angle drive to enable the blender unit 10 to be oriented vertically
in order to receive the sand and other dry chemicals under gravity
flow through the hopper 14. The sand screw assembly or auger A,
Figure 1, has the capability of introducing sand from the storage
area S to a point at least 38" above the expeller of the hopper 14
so that the mass flow rate of sand downwardly through the hopper is
sufficient to produce the desired flow rate of sand in the slurry
through the discharge port. While the apparatus is described and
shown as being truck-mounted, it will be appreciated that it can be
mounted on a fixed support and be oriented vertically or canted at
an angle, such as, in the manner disclosed in hereinbefore referred
to U.S. Patent No. 5,904,419.
The unit 10 also includes a base mount 20 having a
bearing to support the lower end of the drive shaft 12 in journaled
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relation to the mount, a square housing 22 extending upwardly from
the base mount 20 into an enlarged housing area 24 for the speed
reducer mechanism M, and an intermediate casing 26 includes a
bearing 27 within which an intermediate portion of the drive shaft
12 is journaled. The upper end of the casing 26 terminates in a
manifold 28 for the intake port 16 and is attached to a
substantially flat underside 30 of an impeller housing 32 for an
impeller assembly generally designated at 34 within the housing 32.
The underside 30 is of annular configuration and disposed in outer
spaced concentric relation to the drive shaft 12, the impeller
assembly 34 being mounted for rotation on the upper end of the
drive shaft 12.
As shown in Figures 2 and 3, the impeller housing 32 has
a substantially flat top side surface 36 of annular configuration
parallel to the underside 30 and joined to the underside 30 by an
outer continuous wall 38 of generally convex or toroidal cross-
sectional configuration.
The hopper 14 converges downwardly
through a central opening in an upper flat, annular connecting
plate 42 which is attached by suitable fasteners to the plate 40
and has an inner thickened ring-like portion 40. A flat support
plate 41 forms an upper extension of the top side 36 and is affixed
to an outer radial edge of the ring-like portion 40. A butterfly
valve 48 with suitable hand control arm 49 is mounted in the hopper
to seal off the mixer when desired and can assist in regulating the
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flow rate of sand into the impeller housing 32. The discharge port
18 extends tangentially away from the outer wall 38 of the housing
32, and the inlet port 16 extends radially into the housing 26
immediately below the expeller housing 32.
A feature of the impeller assembly 84 resides in the
construction and arrangement of upper impeller vanes 50 and lower
impeller vanes 52 interconnected by a common divider plate 54. The
plate 54 is centered for rotation on the upper end of the drive
shaft 12 by means of a cup-shaped retainer 56. The upper impeller
vanes 50 are bounded by a top plate 58 having radially extending,
circumferentially spaced expeller vanes 60 on its upper surface.
An annular wear plate 62 is adjustably mounted between the support
plate 41 and the vanes 60 by threaded fasteners 63 having lock nuts
63' at one end. The wear plate 62 has a circular rib 62' which
projects downwardly through aligned circular slots 64 in the vanes
60, as best seen from Figure 4, and can be adjusted up or down by
the lock nuts 63' to regulate the spacing of the wear plate 62
above the cover plate 58. In this way, the rib or diverter 62'
cooperates with the expeller vanes 60 in minimizing any return flow
of slurry or liquids toward the central region of the impeller.
The lower vanes 52 are bounded by a bottom cover plate 66
having spaced expeller vanes 68, and a wear plate 59 is mounted in
the underside 30 of the housing 32 beneath the vanes 68. The upper
vanes 50 are shown in detail in Figure 5 and comprise a plurality
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of split, circumferentially spaced vane portions or blades
extending upwardly from an upper surface of the divider plate 54.
Each of the vanes 50 is of generally V-shaped configuration and
split into a radially extending side S1 and a second, trailing side
S2 diverging radially outwardly at an inclined angle away from the
radial side Si, and each of the split vanes or sides S1 and S2 are
formed with a pie-shaped recess or space R1 between sides Si and S2.
The sides S1 and S2 are straight, each side being of generally
rectangular cross-sectional configuration and interconnected at an
inner radial edge T of the divider plate 54. In turn, the outer
radial edges U1 and U2 of the sides S1 and S2 terminate at the outer
radial edge of the divider plate. The angle of divergency and
length of each side S2 is such that a second spacing or recess R2 is
formed between each trailing side S2 and the next successive radial
side S1 of each vane.
In working with granular materials, such as, sand, the
vanes and particularly the sides S1 increase in width or thickness
in outward radial directions on account of the greater wear toward
the outsides of the vanes 50.
In turn, the trailing sides S2
prevent return flow of the liquid into the central area of the
impeller and maintains a more constant pressure as sand flows
outwardly from the eye of the impeller.
The lower vanes 52 shown in Figure 7 are similarly
bounded by a bottom cover plate 66 having downwardly extending,
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,
spaced expeller vanes 68, as described earlier, to discourage
return flow of slurry or liquids around the underside of the
housing. The lower vanes 52 extend downwardly from the divider
plate 54 and are arranged in circumferentially spaced relation.
Each vane 52 has an inner somewhat tangential tip or edge 74, an
arcuate portion 75 curving outwardly from the inner radial edge 74
and a convex surface 75' along the entire length of the vane 52,
the convex surface 75' facing in the direction of rotation of the
impeller assembly over the entire length of each vane and
terminating in an outer radial tip or edge 76.
In addition, a
radially directed split end portion 78 branches outwardly from the
arcuate portion 75 and terminates in an outer radial tip or edge
80. The space or recess 82 between the vanes 52 diverges in an
outward radial direction from the inner tip 74 to the outer tip 80,
and the split end portions 78 have a shallow recess 78'
therebetween.
The lower vanes 52 curve outwardly from the central
opening or intake 16 of the impeller assembly and, under clockwise
rotation of the impeller assembly, the liquid flowing outwardly
between the vanes 52 will undergo an outward radial change in
direction of flow as influenced by the split end portions 78 and
impart more of a swirling action to the liquid into the annulus.
As the liquid flows upwardly around the outside of the divider
plate 54 into the annulus of the impeller casing 32 surrounding the
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impeller vanes 52 and 50 into the upper impeller region, it starts
to mix with the sand which is discharged by the expeller vane
assembly, and the upper split vanes Si and S2 will discourage
counterflow of the liquid/sand slurry and which will eventually be
driven outwardly through the discharge port 18. The
balanced
pressure or balance point between the sand and water in the upper
impeller region can be regulated by the relative length of the
vanes 50 and 52 as well as the liquid pressure and mass flow rate
of sand delivered through the upper hopper as well as the relative
height of the upper impeller vanes 50 to the lower vanes 52.
The lower portion 44 of the hopper terminates above an
expeller vane assembly 84 shown in Figures 4-6 comprised of a base
or mounting plate 85 which is mounted on an inner concentric
portion of thedivider plate 54 for rotation on the drive shaft
12, and a seriesof expeller vanes are made up of a combination
of alternatinglonger, straight radial vanes 86 extending from the
center axis ofthe expeller vane assembly and substantially
shorter but tallervanes 88 extending radially inwardly from the
outer edge of the base or mounting plate 85. The
vanes 86 and
88 have corresponding cross-sections, each having a straight,
generally rectangular supportblock 90 and an upper or outer angled
blade portion 92. The vanes 86 extend radially outwardly from the
upper end of the drive shaftto the outer peripheral edge of the
base or mounting plate 85, and the vanes 88 extend radially
inwardly from the outer edge of the plate 85 for a
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distance such that the shorter vanes 88 will cover substantially
the same area as the longer but lower profile vanes 86 and in this
way equalize the amount of sand or other granular material engaged
by each set of vanes 86 and 88, respectively, so as to avoid
imbalance. Thus, the shorter vanes 88 will first contact the sand
along the outer region of the expeller and throw the sand sideways
and outwardly without contacting the longer vanes 86; and the
longer vanes will contact the sand along the inner region of the
expeller and force it in a circumferential and radially outward
direction with little or no contact with the vanes 88.
Detailed Description of Alternate Embodiments
Figures 9 and 10 illustrate an alternate form of impeller
assembly 34' wherein like or similar parts are correspondingly
enumerated with prime numerals. Thus, the plate 54' is centered
for rotation on the upper end of the drive shaft 12' in the same
manner as described with reference to Figures 5 and 7. It will be
apparent than an expeller vane assembly 84 of the type shown in
Figures 4-6 may be utilized in cooperation with the upper impeller
vanes 50'. The vanes 50' are made up of split, circumferentially
spaced vane portions or blades which extend upwardly from the
divider plate 54' and are progressively increased in thickness from
their inner radial edges T' to their outer radial edges UI' and U2'.
Inaddition, as opposed to being straight, the vanes 50' are
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curved or bowed so as to be of generally arcuate configuration
along their length from the inner edges T' to outer edges U1' and
U2'.
Accordingly, as illustrated, the vanes 50' would present
generally convex surface portions in the direction of rotation of
the impeller 54'. The number of vanes may be varied according to
the capacity or amount of material being pumped through the
assembly.
Figure 10 illustrates a modified form of lower vanes 52'
which are curved or bowed to be of generally arcuate configuration
in a radial direction away from the central drive shaft.
In
addition, the individual vane members increase in thickness or
width from their inner radial edges to their outer radial edges and
correspond in number and spacing to one side S1 of the split vanes
52' and of course the number of vanes may be varied. For example,
Figures 9 and 10 illustrate an upper vane 50' and a lower vane 52'
but could very well be a greater or lesser number depending on the
speed and desired capacity of the blender.
The following working example is given for the purpose of
illustration in the utilization of the blender method and apparatus
of the preferred form of invention in mixing sand and water and
delivering continuously to a high horse power and high pressure
fracturing pump truck: The inlet end of the impeller at the lower
reduced end 44 of the hopper 14 is 10" less the diameter of the
center fastener 82 for the expeller blades 84, and the sand is
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delivered at a constant rate through the auger A to a point no less
than 28" above the expeller in order to reach a vertical speed of
73.55" per second needed to meet the design criteria of 20,000 lbs.
of sand per minute through the opening. Once it has reached the
expeller the sand is trapped by the angle blade portions 92 of the
expeller blade and is pushed down at the same time that it is
accelerated outwardly.
This portion of the expeller blade
increases the time required to accelerate the sand reducing the
impact and the possible crushing of the sand. Again, in order to
reach the design criteria of 20,000 lbs. of sand per minute through
the outlet 18, the expeller blades 86 and 92 are 2.5" and 2" high,
respectively, and impeller vanes 50 are 3.5" in depth and vanes 52
are 2" in depth are rotated at 1050 rpm. The water is pumped into
the inlet 16 with the aid of the booster pump P and is accelerated
upwardly through the lower impeller zone until it reaches the vanes
52 whose inner tips are at a radius of 7". The water is further
accelerated by the vanes 52 until it reaches the outer tips of the
vanes, at a radius of 24", whereupon the liquid is driven into the
annulus and energized to a pressure of approximately 70 psi. The
liquid will then occupy the entire annulus and begin to invade the
upper set of longer impeller vanes 50 which are rotating at the
same rpm as the lower and shorter vanes 52 and therefore opposing
the entrance of the liquid into the upper section of the impeller.
Once the liquid has entered the upper vanes 50 it will have
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dissipated its energy somewhat, and any tendency of the liquid to
reach the eye of the impeller will be overcome by the length of the
upper vanes 50 which will be on the order of 7" compared to the
lower vanes which are on the order of 5". Accordingly, the eye of
the upper impeller will be free of liquid so as not to interfere
with the introduction of the sand from the auger A.
The expeller blades 92 and 86 will impart a radial
velocity on the order of 549.80" per second as a result of which it
is not necessary to have a higher depth of sand expeller vane 50
than 3.5". Furthermore, once the sand has entered blade 50 it will
be accelerated to an exit speed of 1,319.5" per second. Thus, the
spacing between blades S1 and S2 may be more on the order of 0.6" to
1.0" and therefore considerably more compact for the mass rate of
flow of sand being handled. In addition, the expeller blades 50
reduce the area of the vanes which must be exposed to the
pressurized liquid and therefore reduces the torque required to
maintain the requisite rpm and correspondingly reduces the
horsepower required on the engine. It will be evident that the
size of the inlet may be reduced depending upon the amount or
capacity of sand and water being discharged and therefore minimize
the net positive suction head required.
The vane configuration devised for the preferred and
modified forms of invention with the aid of the booster pump enable
close control over the pressure of the solid and liquid materials
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in order to achieve optimum performance. For example, when the
vanes are curved in the same direction as the direction of
rotation, the pressure increases as the rate of flow of the
materials increases and, in curving away from the direction of
rotation, the pressure will decrease. However, any tendency to
decrease can be overcome by adding the radial tip end portions U1
and U2 to the outer radial ends of the vanes. The use of the
booster pump P greatly aids in controlling the flow and pressure
characteristics of the water for a given rpm or speed of rotation
of the vanes. Furthermore, the booster pump maintains a positive
suction head and keeps the system primed should the operation of
the mixture be temporarily stopped. The relative height and length
of the expeller vanes 86 and 88 as well as the relative lengths of
the upper and lower impeller vanes 50 and 52 as well as the RPMs
can be varied to achieve different flow and pressure
characteristics for a given speed of rotation of the vanes. It
will be further evident that the vane configuration of the impeller
vanes 50 and 52 is conformable for use in numerous applications
other than blender apparatus and for example are adaptable for use
in centrifugal pumps or in virtually any application where it is
desirable to control the pressure of liquid or solid particles by
regulating the curvature of the impeller vanes.
It is therefore to be understood that while different
embodiments have been herein set forth and described, various
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modifications and changes may be made therein.
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