U.S. patent application number 17/734797 was filed with the patent office on 2022-08-18 for apparatus for heating fluids.
The applicant listed for this patent is Cavitation Holdings, LLC. Invention is credited to James L. Griggs.
Application Number | 20220260249 17/734797 |
Document ID | / |
Family ID | 1000006303873 |
Filed Date | 2022-08-18 |
United States Patent
Application |
20220260249 |
Kind Code |
A1 |
Griggs; James L. |
August 18, 2022 |
Apparatus for Heating Fluids
Abstract
The apparatus described herein uses a disc wafer-type rotor
featuring channels disposed around its circumference and around the
interior circumference of the rotor housing specifically to induce
cavitation. The channels are shaped to control the size,
oscillation, composition, duration, and implosion of the cavitation
bubbles. The rotor is attached to a shaft which is driven by
external power means. Fluid pumped into the device is subjected to
the relative motion between the rotor and the device housing, and
exits the device at increased temperature. The device is
thermodynamically highly efficient, despite the structural and
mechanical simplicity of the apparatus. Such devices accordingly
provide efficient, simple, inexpensive, and reliable sources of
distilled potable water for residential, commercial, and industrial
use, as well as the separation and evaporation of other
liquids.
Inventors: |
Griggs; James L.; (Acworth,
GA) |
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Applicant: |
Name |
City |
State |
Country |
Type |
Cavitation Holdings, LLC |
Atlanta |
GA |
US |
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|
Family ID: |
1000006303873 |
Appl. No.: |
17/734797 |
Filed: |
May 2, 2022 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16249459 |
Jan 16, 2019 |
11320142 |
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17734797 |
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14575546 |
Dec 18, 2014 |
10222056 |
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16249459 |
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13475351 |
May 18, 2012 |
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14575546 |
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61488061 |
May 19, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F24D 2200/30 20130101;
F24V 40/00 20180501; C02F 2103/10 20130101; C02F 1/36 20130101;
C02F 2103/365 20130101; C02F 1/043 20130101; B01D 1/0011 20130101;
F22B 3/06 20130101; C02F 1/78 20130101; C02F 2101/32 20130101 |
International
Class: |
F22B 3/06 20060101
F22B003/06; F24V 40/00 20060101 F24V040/00; C02F 1/36 20060101
C02F001/36; B01D 1/00 20060101 B01D001/00; C02F 1/04 20060101
C02F001/04 |
Claims
1.-18. (canceled)
19. A method of extracting at least one substance from a fluid
comprising: (a) providing a fluid containing at least one substance
therein; (b) passing the fluid through a cavitation zone; (c)
causing cavitation events in the fluid that produce shock waves and
pressure variations in the cavitation zone, the cavitation zone
being defined between the outer peripheral surface of a rotor and
an interior surface of a housing within which the rotor is
rotatably mounted, the rotor having cavitation inducing structures
on its outer peripheral surface, and wherein the step of causing
cavitation events comprises rotating the rotor within the housing
as the mixture passes through the cavitation zone; and (d)
separating at least one of the substances from the fluid.
20. The method of claim 19, wherein in step (c), the shock waves
and pressure variations are controlled by varying the rotation rate
of the rotor.
21. The method of claim 19, wherein in step (a), the fluid
comprises water.
22. The method of claim 19, further comprising subjecting the
mixture to a non-cavitation based process prior to step (b).
23. The method of claim 19, further comprising subjecting the
mixture to a non-cavitation based extraction process following step
(c).
24. The method of claim 19, wherein the fluid contains at least one
petroleum product.
25. The method of claim 19, wherein the fluid contains at least one
oil.
26. The method of claim 19, wherein the cavitation inducing
structures comprise indentations.
27. The method of claim 19, further comprising repeating step (c)
two or more times.
28. The method of claim 19, further comprising, after step (c),
causing the fluid to flow from the cavitation zone into a tank.
29. The method of claim 19, further comprising, after step (c),
causing at least a portion of the fluid to flow through a heat
exchanger.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to provisional patent
application Ser. No. 61/488,061 filed May 19, 2011 under 35 U.S.C.
.sctn. 119(e).
BACKGROUND OF THE INVENTION
[0002] The present invention is an apparatus for heating liquids
using a rotor and housing featuring indentations therein that
induce cavitation bubbles in the liquid. The heat generated when
these bubbles rapidly collapse is transferred to the fluid. Thus,
the apparatus permits efficient heat transfer to a fluid without a
solid heat exchanger interface.
[0003] There are a variety of patented devices (see table below)
that use mechanical energy to increase the temperature and/or
pressure of fluids. Some of these prior art devices heat the fluid
through friction between the fluid and the walls of a rotor and
housing. In other prior art designs, mechanical agitation of the
liquid generates heat. The '349 patent to Schaefer discloses an
apparatus to produce steam pressure by inducing shock waves in a
distended body of water. The '020 patent to Greiner describes a
rotor and housing assembly where fluids are heated by shearing and
friction between the walls of a rotor and housing containing
circumferential indentations. The Griggs patents disclose a method
of heating fluids through the production of shock waves in the
liquid, where shock waves are induced by pumping a liquid into an
enclosed chamber and spinning a rotor containing
cylindrically-shaped dead-end bores. Venturi tubes are also used to
induce cavitation in liquids.
TABLE-US-00001 U.S. Pat. No. Inventor Issue Date 1,758,207 G. H.
Walker May 13, 1930 2,316,522 J. E. Loeffler Apr. 13, 1943
2,991,764 C. D. French Jul. 11, 1961 3,198,191 S. W. Wyszomirski
Aug. 3, 1965 3,508,402 V. H. Gray Apr. 28, 1970 3,690,302 P. J.
Rennolds Sep. 12, 1972 3,720,372 J. W. Jacobs Mar. 13, 1973
3,791,349 C. D. Schaefer Feb. 12, 1974 4,273,075 D. A. Freihage
Jun. 16, 1981 4,277,020 W. J. Grenier Jul. 7, 1981 4,381,762 A. E.
Ernst May 3, 1983 4,779,575 E. W. Perkins Oct. 25, 1988 4,781,151
G. H. Wolpert, Jr., et. al. Nov. 1, 1988 5,188,090 J. L. Griggs
Feb. 23, 1993 5,385,298 J. L. Griggs Jan. 31, 1995 5,957,122 J. L.
Griggs Sep. 28, 1999 7,089,886 Thoma Aug. 15, 2006
[0004] Mechanically-induced cavitation is a well-known phenomenon,
first encountered in the late 19th century during investigations
into ship propeller design. Rapid motion of propeller blades
through water produces a low-pressure region near the surface of
the propeller blade that results in transient bubbles being formed:
a process now known as cavitation. The subsequent rapid implosion
of cavitation bubbles caused by the high ambient water pressure
results in the generation of enormous turbulence, heat, and
pressure. The temperature generated during the collapse of a
cavitation bubble can exceed 5000 degrees Celsius.
[0005] Although cavitation is generally undesirable in marine
propulsion applications, various devices have been employed for the
last few years for the production and implosion of cavitation
bubbles for research in ultrasound, acoustical cavitation for
chemical processes and related fields.
[0006] The apparatus described herein is intended for applications
in fluid purification, distillation, and even pasteurization.
Conventional technologies for purification, distillation, and
pasteurization typically involve direct heating of a fluid. In
direct heating, heat exchange occurs at a solid interface between a
heat source and the subject fluid. In other words, as a fluid flows
through a heat exchanger, heat is transferred to the fluid via
direct contact between the fluid and the wall of the heat
exchanger. However, direct heating has a number of disadvantages.
First, direct heating results in heat exchanger scaling or coking.
This necessitates relatively frequent maintenance to remove the
scaling or coking. In the pasteurization context, direct heating
can result in scorching and destruction of the product to be
pasteurized.
SUMMARY OF THE INVENTION
[0007] The present invention solves these problems because using
cavitation-induced heating eliminates the heat transfer interface;
heat transfer occurs directly within the fluid. The apparatus
disclosed herein purifies fluids through distillation by
mechanically generating cavitation in order to heat the fluid. When
the cavitation bubbles collapse, the heat generated is transferred
to the fluid directly.
[0008] Cavitation-induced heating has a number of advantages in
heating fluids. In the petroleum industry, cavitation-induced
heating allows petroleum products to be heated directly in storage
tanks in the field, on pipelines, or on barges to facilitate
pumping and unloading in cold weather, and heavy oil products could
be heated for processing without heat exchanger scaling. In ethanol
production, cavitation-induced heating eliminates the need for a
steam boiler and allows up to four steps in the distillation
process to be combined, which reduces production time and cost. In
dairy production, cavitation-induced heating results in reduced
maintenance, since pasteurization would occur without direct
contact between the milk and a heat exchanger surface. This is
particularly beneficial in the pasteurization of high fat dairy
products. Cavitation-induced heating has also shown promising
ability in generating relatively high concentrations (up to 40%) of
hydrogen peroxide (H.sub.2O.sub.2) from tap water. A potential
medical application of the apparatus described herein destroys
pathogens though cavitation-induced heating of blood or other
bodily fluids.
[0009] One of the most popular current applications, however, is
use of cavitation-induced heating to purify polluted water through
distillation. Cavitation-induced heating systems have been used in
purifying glycol-tainted water used in airport de-icing operations.
Another application is purifying water that has been used in
hydraulic fracturing (or "fracking") operations used in natural gas
production fields. The water used to fracture natural gas bearing
rock, or "frac water", is usually contaminated with sulfur and
other minerals during the process and requires treatment before its
return to the environment. A block diagram of a typical system is
shown in FIG. 7, in which a self-contained, easily movable 40-foot
trailer houses the cavitation generators, motors, and other
components described below.
[0010] Another potential application of cavitation-induced heating
is purification of seawater. Current sea water distilling
technology typically uses electricity to generate heat. However,
energy is lost generating steam to produce the electricity, and
additional energy is lost in transmitting electricity to the
desalinization plant. However, using cavitation-induced heating
would be extremely efficient in converting seawater into steam. As
the steam is condensed back across a low pressure-condensing
generator, both potable water and electricity could be
produced.
[0011] The preferred embodiment of the present invention uses a
shaft-driven, disc wafer type rotor (for easy modification for size
and production design) rotating at relatively high speed (1600-4000
RPM) within a housing to mechanically generate cavitation bubbles
in a fluid being pumped through the cavity within the housing past
the spinning rotor. The shaft may be driven by electric motor,
combustion engine, windmills, animal power or other motive means
known to the art. Both the rotor and the housing have
non-cylindrical shaped irregularities which induce cavitation.
Unlike the systems described in the prior patents to Griggs which
had cylindrical shaped dead-end bores in the rotor only, the
embodiments described herein generate cavitation using indentations
running across both the rotor and the interior surface of the
housing, as shown in FIGS. 2-6. These indentations will be
described in greater detail below; however, the general principle
is that as fluid flows past indentations in the rotor, low pressure
regions are generated, resulting in the formation of transient
cavitation bubbles. When these transient bubbles collapse, heat is
imparted directly to the fluid. Heat is therefore rapidly generated
and transferred to the fluid without heat transfer having to occur
between the fluid and a surface.
[0012] It is therefore an object of the present invention to
provide a device for heating a fluid using a rotor and a stationary
housing, which device is structurally simple with reduced
manufacturing and maintenance costs. Maintenance costs are reduced
because, in one preferred embodiment, seals are located on only one
side of the generator. Mechanical seals typically are the most
maintenance-intensive components of the system, requiring frequent
replacement. Prior designs by Griggs included bearing and seal
assemblies on both sides of the shock generator unit; however, the
current design only has bearings and seals on one side.
[0013] It is an additional object of the present invention to
produce a mechanically elegant and thermodynamically highly
efficient means for increasing pressure and/or temperature of
fluids such as water (including, where desired, converting fluid
from liquid to gas phase).
[0014] It is an additional object of the present invention to
provide a system for generating and imparting heat within a fluid
for residential, commercial and industrial applications, using
devices featuring a mechanically driven cavitation-inducing rotor
and housing.
[0015] Other objects, features and advantages of the present
invention will become apparent with reference to the remainder of
this document.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is an isometric rendering of the components of a
cavitation-based distillation system.
[0017] FIG. 2 shows an isometric rendering of the cavitation
generator unit and motor, with a cutaway view of the cavitation
generator showing the irregularities in the rotor and rotor
housing.
[0018] FIG. 3 shows a cross sectional cutaway view showing the
cavitation generating irregularities of the rotor and rotor
housing.
[0019] FIG. 4 shows an embodiment of the cavitation generator
having smoothly curved channels in the circumference of the rotor
and the rotor housing
[0020] FIG. 5 shows another embodiment of the cavitation generator
having angular, square-shaped channels in the circumference of the
rotor and the rotor housing.
[0021] FIG. 6 shows another embodiment of the cavitation generator
having open polygonal shaped channels in the circumference of the
rotor and the rotor housing.
[0022] FIG. 7 is a system block diagram of an application of the
invention used to purify waste water byproducts from hydraulic
fracturing operations used in natural gas production.
DETAILED DESCRIPTION OF THE INVENTION
[0023] FIG. 1 shows the overall configuration of the preferred
embodiment of a system 20 designed to purify contaminated water,
such as frac water, in batches. The contaminated fluid is first
pumped into tank 8. From the tank, the fluid passes through tank
outlet line 17 to the inlet of cavitation generator 1. As shown in
FIG. 2 and as described above, the cavitation generator consists of
two primary parts, a rotor housing 4 and a rotor 5. The rotor 5 is
driven by a shaft 3 that is coupled to a motor 2. In the preferred
embodiment, an electric motor is used. The size of the motor is
dependent on the size of the unit; typically, 500 or 1000
horsepower motors would be used for applications requiring
purification of up to 100,000 gallons per day. One skilled in the
art will realize that any type of motive power capable of providing
torque to a shaft can be substituted for an electric motor,
although in these cases additional mechanical complexity may be
required in the form of gears to match motor speed with the desired
rotor rotational speed (typically 1600-4000 RPM).
[0024] The speed of the rotor is one of several variables involved
in inducing cavitation. Typically, the outer edge of the rotor
indentations (i.e. the tips shown in FIGS. 3-6) must have a speed
of at least 90 feet per second to induce cavitation in frac water,
so the smaller the rotor diameter, the larger the RPM required to
generate the required tip speed, and vice versa. The RPM range
given above was found to be sufficient for rotors ranging in size
from 5 inches in diameter to 36 inches in diameter.
[0025] As contaminated fluid passes from tank 8 into the inlet of
the cavitation generator 1, it fills a cavity between the rotor 5
and the rotor housing 4 as shown in FIG. 3. For applications
involving frac water, the gap between the rotor and housing is
0.250 inches. This gap, however, varies with the type of fluid
designed to be heated. The exterior of the rotor and the interior
of the housing contain indentations that are designed to maximize
cavitation in the fluid flowing through the cavitation
generator.
[0026] As shown in FIG. 3, these indentations may be inclined into
or away from the direction of rotation. The angle of inclination of
the indentations either into or away from the flow and the depth of
the indentations themselves will depend on the nature of the fluid
to be heated. FIGS. 3, 5-6 shows indentations that are defined by
the intersection of planar surfaces, while FIG. 4 shows
indentations that are curved.
[0027] Cavitation bubbles are generated as the low-pressure
boundary layer of the water in contact with the surface of the
rapidly spinning rotor is swept over the lip of the indentations.
This is similar to water flowing around a sharp bend in a pipe,
where the pressure on the outside (concave wall) of the curve is
higher than that on the inside (convex wall), where cavitation can
occur. In the pipe the bubbles would be carried away by the
movement of the fluid, but in the present invention the rotor
indentations` shape and depth act to fix the location of the
cavitation bubbles until the bubbles implode generating heat which
is immediately imparted to the fluid. Additionally as the harmonics
of the device come into play the bubbles began to oscillate and
continue to reform and collapse. Bubble size and collapse are the
results of the specifics of the irregularities and rotor design,
causing millions of cavitation bubbles to form and collapse
simultaneously. The heat generated by the collapsing bubbles is
imparted directly to the fluid.
[0028] The depth, shape, and number of these indentations, their
inclination relative to the fluid flow, the speed of the outer part
of the rotor (i.e. the tip), as well as the amount of time the
fluid spends inside the cavitation generator determine how
effective the cavitation generator is at generating heat. These
variables depend upon the nature of the fluid to be heated. The
viscosity of the fluid is a major factor in optimizing the design
of the rotor and housing. Higher viscosity fluids are generally
more resistant to the formation of cavitation. All of the current
embodiments feature indentations in both the rotor and the interior
housing, which tend to increase the shear and therefore are ideally
suited to counteract viscosity effects in the fluid.
[0029] Contaminated fluid pumped into cavitation generator 1 flows
past the rotor, which is moving at high speed relative to the
fluid. Hydrodynamic flow patterns over the irregularities described
above in the rotor and housing result in low pressure regions in
the indentations, which causes the rapid formation and collapse of
cavitation bubbles, resulting in heat which is then transferred to
the fluid. The heated fluid passes out of the cavitation generator
1 and back into tank 8 through tank inlet line 9. The temperature
differential between the inlet and outlet of the cavitation
generator is measured by water inlet temperature sensor 18 and
water outlet temperature sensors 19 and displayed on panel 6. The
contaminated fluid is recirculated between tank 8 and cavitation
generator 1 until the fluid in the tank begins to vaporize.
Pressure in the system is maintained by recirculation pump 7. In
the preferred embodiment, recirculation pump is a centrifugal pump
driven by a 1 horsepower electric motor controlled from control
panel 10.
[0030] As fluid continuously circulates from tank 8 to the
cavitation generator 1 and back, the temperature of the fluid rises
until steam is produced in tank 8. The steam produced from the
contaminated fluid in the tank passes through the top of tank 8
into steam supply line 12 and then into heat exchanger 13. In heat
exchanger 13, the steam condensed and passes through condensate
outlet line 15 and is collected. The collected fluid has now been
purified and can be returned to its source. Cooling water from an
outside source, such contaminated frac water as shown in FIG. 7, is
provided to the system through heat exchanger cooling water inlet
14. Power to the recirculation pump 7 is controlled at panel 10,
system temperatures are displayed on panel 6, and power is provided
through power box 11.
[0031] The fluid purification system described above processes
contaminated fluid in batches. Once the level of the contaminated
fluid in the tank decreases to a certain level, additional fluid is
added. At the end of the purification process, remaining liquid in
tank 8 is drained through tank drain valve 16.
[0032] Prior art cavitation generators by Griggs used cylindrical
dead-end bores in the rotor to generate shock waves in the fluid.
However, it was discovered that cavitation effects were enhanced by
modifying Griggs' design in two ways.
[0033] First, the Griggs patents only disclose cylindrical
indentations disposed around the circumference of the rotor.
However, the current invention uses linear or curvilinear channels
in the inner surface of the rotor housing that are similar to, and
complimentary with, similar channels on the rotor's circumference.
It was discovered that the presence of channels in the inner
surface of the housing as well as on the rotor increases shear in
the fluid, encouraging turbulence and greatly enhancing cavitation
and water hammer effect. As explained above, cavitation is
desirable in this application because the rapid formation and
violent collapse of cavitation bubbles generated results in
significant heat being generated internally in the fluid.
[0034] Second, instead of cylindrical dead-end bores disposed
around the circumference of the rotor, the channels in the rotor's
circumference extend across the width of the rotor, which results
in increased surface area exposed to the fluid. In certain
preferred embodiments shown in FIGS. 2, 3, 5 and 6, when viewed in
cross section, the channels have one or more angular corners
defined by two or more intersecting planar surfaces in the rotor
where the linear intersection of these two surfaces is oriented
generally parallel to the rotor's rotational axis. In other
embodiments, however, the channels have smoothly curved walls
ending with a discontinuity at the tip, such as those shown in FIG.
4.
[0035] Initial test results indicate that the currently disclosed
design is more efficient than prior art models. Distilling units
using designs disclosed herein are approximately 30% smaller than
prior art units based on Griggs' earlier cylindrical dead-end bore
design, for the same amount of distilling capacity.
[0036] Other rotor and housing embodiments specifically adapted for
heating contaminated water ("frac water") used in hydraulic
fracturing ("fracking") operations are shown in FIGS. 5 and 6. One
embodiment shown in FIG. 5 has a rotor that is 8.5 inches in
diameter. The rotor channels disposed circumferentially when viewed
in cross section are rectangular with a depth of approximately 0.75
inch and a width of approximately 0.5 inch. The rotor housing is
10.5 inches in outside diameter and 9.0 inches in inner diameter,
and the corresponding channels in the rotor housing are typically
0.5 inches in depth and 0.5 inches in width. The gap between the
edge of the mouth of the channels in the rotor and the rotor
housing is 0.25 inches.
[0037] A second rotor-rotor housing embodiment used in frac water
purification is shown in FIG. 6. The rotor is 6.75 inches in
diameter, and the channels in the rotor are defined by open
pentagonal channels disposed around the rotor's circumference as
shown in FIG. 6. The bottom of the channels are typically square,
with 0.5 inches on a side, with the channels flaring out at an
angle to the outer circumference of the rotor (i.e. the tip of the
tooth attached to the rotor). The outer diameter of the rotor
housing is 10.5 inches and the inner diameter is 7.25 inches,
leaving a gap of 0.25 inches between the tip of the pentagonal
teeth of the rotor and the mouth of the channels in the rotor
housing.
[0038] Also, it should be noted that although the rotor herein may
be cylindrical, the rotor used in the preferred embodiments is a
disc-wafer type rotor i.e., a flat disc with thickness less than
its diameter, as opposed to the cylinder-shaped rotor disclosed in
the prior Griggs patents. In the embodiments shown in FIGS. 5 and
6, the width of the rotor is 1.5 inches and the outside width of
the rotor housing is 1.875 inches.
[0039] Yet another embodiment that is a working prototype for a
full-scale system features a 9.5 inch diameter rotor that is 1 inch
wide. The rotor is driven with a 25 horsepower motor to 4000 RPM.
Such a prototype has purified 6.75 gallons of water per hour. A
larger embodiment that is also a working prototype has a 28 inch
diameter rotor which is 3 inches wide. the rotor is driven by a 125
horsepower diesel engine at 1800 RPM and distills 20 gallons of
water every 2 hours and 20 minutes.
[0040] Another, large-scale embodiment of the system that is used
to reclaim contaminated frac water is shown in FIG. 7. Return water
from the fracturing process is pumped through a pre-screen filter
21, then into a mixing tank 22 where it is mixed with ozone from an
ozone generator 23. The ozone-treated water from mixing tank 22 is
then pumped to a 40 foot long container 24 housing the system 20
described above and shown in FIG. 1. The heated water is sent
through a high-pressure jet pump 25, a sand bed filtration system
26, and then to heat exchanger 27. In heat exchanger 27, the steam
is condensed through heat exchange with return water from the
fracturing process. The return water is thereby pre-heated before
it passes through pre-screen filter 21. The condensed water is then
stored in a separation tank 28, before being either discharged to
the environment or reused in the fracking process.
* * * * *