U.S. patent application number 11/899174 was filed with the patent office on 2009-03-05 for rotational vessel heating.
This patent application is currently assigned to Total Separation Solutions LLC. Invention is credited to Patrick F. Hobbs, Kevin W. Smith.
Application Number | 20090056645 11/899174 |
Document ID | / |
Family ID | 40405476 |
Filed Date | 2009-03-05 |
United States Patent
Application |
20090056645 |
Kind Code |
A1 |
Hobbs; Patrick F. ; et
al. |
March 5, 2009 |
Rotational vessel heating
Abstract
Aqueous fluids are heated or boiled in a tank or vessel by
causing cavitation in the fluid within the tank or vessel. A rotor
having cavities on its cylindrical surface is rotated within a
closely dimensioned housing submerged in the fluid, deliberately
causing cavitation which heats the aqueous fluid without the use of
flame or heat exchange surface. An electric motor which powers the
rotor may itself be submerged in the tank or boiler vessel. The
rotor includes radial channels for imparting centrifugal impetus to
the fluid as it flows toward the cavitation zone.
Inventors: |
Hobbs; Patrick F.; (Houston,
TX) ; Smith; Kevin W.; (Houston, TX) |
Correspondence
Address: |
William L. Krayer;Attorney at Law
1771 Helen Drive
Pittsburgh
PA
15216
US
|
Assignee: |
Total Separation Solutions
LLC
|
Family ID: |
40405476 |
Appl. No.: |
11/899174 |
Filed: |
September 5, 2007 |
Current U.S.
Class: |
122/26 ; 126/247;
416/231A |
Current CPC
Class: |
B01D 1/0011 20130101;
F22B 3/06 20130101 |
Class at
Publication: |
122/26 ; 126/247;
416/231.A |
International
Class: |
F22B 3/06 20060101
F22B003/06; F04D 29/18 20060101 F04D029/18; F24C 9/00 20060101
F24C009/00 |
Claims
1. Apparatus for heating a liquid comprising a reservoir, a flux
stress device within said reservoir capable of heating liquid in
said reservoir by flux stress when said flux stress device is
immersed in said liquid, an inlet for admitting makeup liquid to
said reservoir, and at least one outlet from said reservoir for
removing liquid heated by said flux stress device, said liquid
being removed as heated liquid, vapor or steam.
2. Apparatus of claim 1 wherein said flux stress device includes a
rotor which generates flux stress in a liquid when it is immersed
in said liquid and rotated.
3. Apparatus of claim 2 including a motor or engine for rotating
said rotor, said motor or engine being located within said
reservoir.
4. Apparatus of claim 2 including a motor or engine for rotating
said rotor, said motor or engine being located outside said
reservoir.
5. Apparatus of claim 1 including a conduit for makeup liquid
leading to said inlet.
6. Apparatus of claim 5 including a filter in said conduit.
7. Apparatus of claim 1 wherein said reservoir is a boiler vessel
capable of containing up to 250 pounds per square inch
pressure.
8. Apparatus of claim 7 wherein said boiler vessel is capable of
containing at least 500 pounds per square inch pressure.
9. Apparatus of claim 1 wherein said flux stress device is a water
brake dynamometer.
10. Apparatus of claim 1 wherein said flux stress device is a
cavitation device.
11. A liquid reservoir including a cavitation device within said
liquid reservoir.
12. The liquid reservoir of claim 11 wherein said cavitation device
comprises a rotor having cavities for inducing cavitation in a
flowing liquid, and a housing defining a path for said flowing
liquid, said path passing by said cavities.
13. The liquid reservoir of claim 12 including an aqueous fluid in
said reservoir in an amount sufficient to submerge said cavitation
device.
14. The liquid reservoir of claim 13 including means for
substantially continuously introducing makeup liquid to said liquid
reservoir and substantially continuously removing at least one of
heated liquid, steam, or vapor from said reservoir.
15. A boiler vessel including a cavitation device within said
boiler vessel.
16. The boiler vessel of claim 15 wherein said cavitation device
comprises a rotor having cavities for inducing cavitation in a
flowing liquid, and a housing defining a path for said flowing
liquid, said path passing by said cavities.
17. The boiler vessel of claim 15 including an aqueous fluid in
amount sufficient to submerge said cavitation device.
18. The boiler vessel of claim 15 including an outlet for steam and
vapor.
19. The boiler vessel of claim 15 including an outlet for
blowdown.
20. The boiler vessel of claim 15 including a conduit for
introducing incoming aqueous fluid to said boiler vessel.
21. The boiler vessel of claim 15 including means for inducing
subatmospheric pressure within said vessel.
22. The boiler vessel of claim 20 including a filter on said
conduit for introducing incoming aqueous fluid.
23. The boiler vessel of claim 20 wherein said conduit for
introducing incoming aqueous fluid to said boiler vessel introduces
said aqueous fluid through said cavitation device.
24. The boiler vessel of claim 23 including a filter on said
conduit for introducing incoming aqueous fluid.
25. The boiler vessel of claim 16 wherein said rotor is mounted on
a substantially horizontal axis.
26. The boiler vessel of claim 16 wherein said rotor is mounted on
a substantially vertical axis.
27. The boiler vessel of claim 15 wherein said boiler comprises a
substantially cylindrical vessel and said cavitation device
comprises a substantially cylindrical rotor having cavities on its
surface, said cavities being disposed in proximity to the interior
wall of said substantially cylindrical vessel.
28. The boiler vessel of claim 15 wherein said cavitation device
includes a submersible motor for powering said cavitation device,
which motor is also within said boiler vessel.
29. A cavitation device rotor for immersion in liquid, said rotor
comprising a body having a substantially cylindrical surface and
two faces, said body having a central opening on at least one face
for receiving a rotatable shaft for rotating said rotor and a
plurality of channels opening on at least one face for admitting
liquid when said rotor is immersed in said liquid and transporting
it to said substantially cylindrical surface, and a plurality of
cavities on said substantially cylindrical surface.
30. The cavitation device rotor of claim 29 wherein said cavities
are wider at their outlets than in their portions closer to the
axis of said rotor.
31. The cavitation device rotor of claim 29 wherein said channels
are substantially radial channels.
32. A cavitation device for immersion in a boiler vessel comprising
the rotor of claim 29 and a housing substantially surrounding and
in proximity to said substantially cylindrical surface of said
rotor.
33. The cavitation device of claim 32 including a submersible
electric motor for turning said rotor.
34. Boiler apparatus comprising a vessel, a cavitation device rotor
of claim 29 in said vessel, and a housing substantially surrounding
and in proximity to the substantially cylindrical surface of said
rotor.
35. Boiler apparatus comprising a vessel having a substantially
cylindrical interior surface in at least a portion of said vessel,
and a substantially cylindrical cavitation rotor within said
vessel, said substantially cylindrical rotor also having a
substantially cylindrical surface, said cylindrical rotor surface
having a diameter slightly smaller than at least a portion of the
interior surface of said vessel, said rotor surface and said
portion of said interior surface being substantially
concentric.
36. Boiler apparatus of claim 35 wherein said cavitation rotor has
a plurality of cavities on said substantially cylindrical surface
and a plurality of interior channels for transporting liquid from
near the center of said rotor to said substantially cylindrical
surface thereof.
37. Boiler apparatus of claim 35 including a submersible motor
within said vessel for powering said cavitation rotor.
38. Method of heating an aqueous fluid comprising placing said
aqueous fluid in a boiler vessel and causing cavitation within said
aqueous fluid in said boiler vessel.
39. Method of claim 38 including continuously or intermittently
feeding said aqueous fluid to said boiler vessel.
40. Method of claim 38 including continuously or intermittently
removing steam or vapor from said boiler vessel.
41. Method of claim 38 including continuously or intermittently
removing blowdown or hot aqueous fluid from said boiler vessel.
42. Method of claim 38 wherein said cavitation is accomplished by a
cavitation device.
43. Method of providing hot aqueous liquid or steam comprising
substantially continuously passing aqueous liquid into a reservoir,
inducing flux stress in said liquid while it is in said reservoir,
thereby elevating the temperature of said liquid, and substantially
continuously removing said liquid from said reservoir in a liquid
or gaseous state.
44. Method of claim 43 wherein said flux stress is induced
primarily by shear.
45. Method of claim 43 wherein said flux stress is induced
primarily by turbulence.
46. Method of claim 43 wherein said flux stress is induced
primarily by cavitation.
47. Method of heating an oilfield fracturing fluid in a tank
comprising immersing a cavitation device in said tank and operating
said cavitation device to induce cavitation in said fracturing
fluid, thereby elevating its temperature.
48. Method of claim 47 wherein said cavitation device includes a
submersible motor.
49. Method of removing water from a dilute oilfield fluid
comprising heating said dilute oilfield fluid in a boiler vessel of
claim 15 and removing steam or vapor therefrom.
50. Method of claim 49 including drawing a vacuum on said boiler
vessel.
Description
TECHNICAL FIELD
[0001] The invention is a liquid heater which heats a reservoir of
aqueous liquid by inducing flux stress within the liquid. A flux
stress inducing device, which may be a cavitration device,
including its electric motor in one version, is immersed in the
liquid in the vessel. Hot water, steam, vapor and blowdown are
readily removed from the reservoir in a conventional manner.
BACKGROUND OF THE INVENTION
[0002] It is known that turbulence, shear, and cavitation within a
liquid will elevate its temperature. For many purposes, the
generation of shear, turbulence and cavitation is considered to be
a waste of energy, and much attention in pump design, for example,
has been devoted to avoiding or suppressing these effects. Some
workers, however, have sought to take advantage of the fact that
the temperature of the liquid may be elevated without the use of
flame or even a heat transfer surface of any kind, and have
designed machines deliberately to subject the fluid in them to such
tortuous flow. Typically, the liquid passes through the machine for
heating and flows to a different location for heat transfer or
other use, and is continuously recycled to the machine. See, for
example, Pope U.S. Pat. No. 5,341,768.
[0003] While the art has used such machines for heating flowing
liquids, to our knowledge it has not successfully designed an
apparatus to elevate the temperature of a body of water within a
vessel, tank, boiler, or other reservoir by turbulence, shear,
and/or cavitation
SUMMARY OF THE INVENTION
[0004] We have invented a water heater using a flux stress device
to supply heat. The flux stress device is immersed within the water
heater reservoir. Placing the flux stress device within the
reservoir enables excellent circulation of hot liquid within the
vessel (reservoir) and excellent control of the heating process.
The flux stress device can heat a wide variety of solutions and
slurries.
[0005] It is known to convert mechanical energy into thermal energy
in a fluid by causing the fluid to follow a tortuous or stressful
path to create shear, turbulence, cavitation or a combination of
one or more of these. A tortuous path may be one featuring
diversions, obstacles or protuberances which induce significant
turbulence. An example of a stressful path for generating shear is
one passing between two closely opposing surfaces, one of which is
advantageously moving with respect to the other. A paradigm of a
cavitation path is a path including cavities capable of alternately
creating and imploding low-pressure vacuities in the fluid. We use
the term "flux stress" to describe generically all three of these
effects, and a flux stress device to mean any device which will
elevate the temperature of a fluid by flux stress. It is immaterial
for our purposes whether the flux stress causes an alteration or
physical degradation of a component of the fluid, such as a
viscosity-imparting polymer. We define "flux stress" as shearing
(sometimes called "shear stress," or simply "shear"), turbulence,
or cavitation, or a combination of more than one of these,
resulting in the heating of a fluid, wherein thermal energy is
induced in the fluid by the stress of the shearing, turbulence, or
cavitation. In addition, some devices of the prior art recognize
friction within a device as an effect which will heat fluid in it.
In many such prior art cases, friction implies primarily a form of
stress caused by flowing against solid parts which may or may not
be designed deliberately to cause a tortuous flow, and may even in
some cases imply the generation of heat due to the motion or
resistance of solid particles suspended in the fluid. Because
turbulence-induced heat is the primary result in either case, we do
not intend to exclude friction, so defined, as a phenomenon which
elevates the temperature of the fluid in a flux stress device.
[0006] The substantially parallel surfaces frequently used to
create shearing and/or turbulence need not be planar or cylindrical
surfaces--for example, a conical surface may be nested within and
close to another conical surface, and the fluid caused to flow
between the two surfaces, one or both of which may be turning; if
both are turning, they will advantageously turn in opposite
directions. Turbulence and shearing between two closely aligned
surfaces or within a conduit or passage induces thermal energy
within the fluid from the mechanical energy of the fluid flux,
without dependence on a heat transfer surface, and the generation
of thermal energy may be enhanced by rotating or otherwise moving
one surface with respect to the other while the fluid is caused to
pass between them.
[0007] Cavitation devices are designed deliberately to generate
heat by cavitation. Cavitation occurs in a fluid when the fluid
flows in an environment conducive to the formation of
partial-vacuum spaces or bubbles within the fluid. Since the spaces
or bubbles are partial vacuum, they almost immediately implode,
causing the mechanical or kinetic energy of the fluid to be
converted into thermal energy. In many devices, such as most pumps,
cavitation is an occurrence to be avoided for many reasons, not
least because of convulsions and disruption to the normal flow in
the pump, but also because of the loss of energy when the
mechanical energy of the pump is converted to undesired heat
instead of being used to propel the fluid on a desired path. There
are, however, certain devices designed deliberately to achieve
cavitation in order to increase the temperature of the fluid
treated. Such cavitation devices are manufactured and sold by Hydro
Dynamics, Inc., of Rome, Ga., most relevantly the devices described
in U.S. Pat. Nos. 5,385,298, 5,957,122 6,627,784 and particularly
5,188,090, all of which are hereby specifically incorporated herein
by reference in their entireties. These patents may be referred to
below as the HDI patents.
[0008] The basic design of the cavitation devices described in the
HDI patents comprises a cylindrical rotor having a plurality of
cavities bored or otherwise placed on its cylindrical surface. The
rotor turns within a closely proximate cylindrical housing,
permitting a specified, relatively small, space or gap between the
rotor and the housing. Fluid usually enters at the face or end of
the rotor, flows toward the outer surface, and enters the space
between the concentric cylindrical surfaces of the rotor and the
housing. While the rotor is turning, the fluid continues to flow
within its confined space toward the exit at the other side of the
rotor, but it encounters the cavities as it goes. Flowing fluid
tends to fill the cavities, but is immediately expelled from them
by the centrifugal force of the spinning rotor. This creates a
small volume of very low pressure within the cavities, again
drawing the fluid into them, to implode or cavitate. This
controlled, semi-violent action of micro cavitation brings about a
desired conversion of kinetic and mechanical energy to thermal
energy, elevating the temperature of the fluid without the use of a
conventional heat transfer surface.
[0009] Benefits of the HDI cavitation devices include that they can
handle slurries as well as many different types of solutions, they
can be used to concentrate such slurries and solutions by
facilitating the removal of steam and vapor from the fluid being
treated, and the heating of the fluid occurs within the fluid
itself rather than on a heat exchange surface which might be
vulnerable to scale formation and ultimately to a significant
reduction in heat transfer.
[0010] Definition: We use the term "cavitation device" to mean and
include any device designed to impart thermal energy to flowing
liquid by causing bubbles or pockets of partial vacuum to form
within the liquid it processes, the bubbles or pockets of partial
vacuum being quickly imploded and filled by the flowing liquid. The
bubbles or pockets of partial vacuum have also been described as
areas within the liquid which have reached the vapor pressure of
the liquid. The turbulence and/or impact, sometimes called a shock
wave, caused by the implosion imparts thermal energy to the liquid,
which, in the case of water, may readily reach boiling
temperatures. The bubbles or pockets of partial vacuum are
typically created by flowing the liquid through narrow passages
which present side depressions, cavities, pockets, apertures, or
dead-end holes to the flowing liquid; hence the term "cavitation
effect" is frequently applied, and devices known as "cavitation
pumps" or "cavitation regenerators" are included in our definition.
Steam generated in the cavitation device can be separated from the
remaining, now concentrated, water and/or other liquid which
frequently will include significant quantities of solids small
enough to pass through the device. The term "cavitation device"
includes not only all the devices described in the above itemized
HDI U.S. Pat. Nos. 5,385,298, 5,957,122 6,627,784 and 5,188,090 but
also any of the devices described by Sajewski in U.S. Pat. Nos.
5,183,513, 5,184,576, and 5,239,948, Wyszomirski in U.S. Pat. No.
3,198,191, Selivanov in U.S. Pat. No. 6,016,798, Thoma in U.S. Pat.
Nos. 7,089,886, 6,976,486, 6,959,669, 6,910,448, and 6,823,820,
Crosta et al in U.S. Pat. No. 6,595,759, Giebeler et al in U.S.
Pat. Nos. 5,931,153 and 6,164,274, Huffman in U.S. Pat. No.
5,419,306, Archibald et al in U.S. Pat. No. 6,596,178 and other
similar devices which employ or include a shearing effect between
two close surfaces, at least one of which is moving, such as a
rotor, and/or at least one of which has cavities of various designs
in its surface (a cavitation zone) as explained above. Shearing and
turbulence commonly occurs in cavitation devices, and possibly
should not be ignored in considering their heat generating
abilities, but most of the thermal energy imparted to the liquid in
a cavitation device is by way of cavitation, by definition.
[0011] As a means for heating or boiling water or other aqueous
fluids, the existing designs of cavitation devices exhibit many
benefits, but there remains a need for improvement. It is difficult
to control the separation of steam and vapor from the remaining
concentrated liquid at the exit of the device. As one approach to
this problem, at least a portion of the heated throughput of the
cavitation device may be sent to a flash tank, for the separation
of liquid and gaseous or vapor phases, thus necessitating a whole
set of additional equipment, valves and controls. Also, the typical
cavitation device would benefit from a practical method of
maintaining pressure on the cavitation zone, to enhance the
cavitating effect.
[0012] Our invention includes a boiler using a cavitation device to
supply heat. The cavitation device is within the boiler vessel and
may be totally immersed. Placing the cavitation device within the
vessel enables excellent circulation of hot fluid within the vessel
and recycling of the fluid through the (desirably) immersed
cavitation device to provide excellent control of the heating
process entirely within the vessel. The cavitation device can heat
a wide variety of solutions and slurries.
[0013] While we describe our invention as in many instances using a
cavitation device, we may also use various flux stress devices
which do not provide heating by cavitation. Such devices include,
broadly, dynamometers (some of which have come to acquire that name
in spite of the fact they may not measure anything) and water
brakes. Water brakes and other types of absorbing dynamometers
convert the energy of a rotor on a turning shaft into thermal
energy due to the turbulence and/or shear stress generated in the
fluid passed by it in proximity to another surface, some of which
may include protuberances to cause local turbulence but not
cavitation.
[0014] Our invention includes a method of making steam comprising
causing flux stress by a flux stress device at least partially
submerged in a body of aqueous fluid within a reservoir, which may
be called a boiler or boiler vessel.
[0015] Our invention includes a method of making steam comprising
causing cavitation by a cavitation device at least partially
submerged in a body of aqueous fluid within a boiler. By "aqueous
fluid" we mean liquid water such as would normally occupy a
significant portion of a boiler vessel. But because of the ability
of our invention to handle a wide variety of solutions and
slurries, we intend for the term "aqueous fluid" to include
solutions and slurries of water including up to and even in excess
of 50% non-water materials by weight, either dissolved, particulate
(if the particulates are suspended in the liquid, they will
desirably be of a size able to pass through the cavitation device),
or both, and including the possibility of organic liquids and/or
other non-aqueous liquids. For example, the term aqueous fluid thus
includes many types of industrial fluids, including used oilfield
fluids. The cavitation device will normally be immersed in the
aqueous fluid, but can operate when it is only partially submerged.
Our invention thus includes a boiler or boiler vessel having a
cavitation device within the boiler or boiler vessel as a source of
heat. Our invention is useful for heating or boiling any aqueous
fluid as defined above.
[0016] Any such aqueous fluid is introduced to a reservoir and
removed as heated fluid, either as a liquid, steam, or vapor. This
process may be substantially continuous, as is frequently the case
with a boiler, or it may be intermittent, as is commonly the case
with a water heater. Our objective is to heat the body of water in
the reservoir where it is utilized as a source or supply of steam,
vapor, or heated liquid. To further describe this process, we use
the term "makeup liquid" for the aqueous fluid which is
continuously or intermittently introduced to the reservoir, which
may be a boiler vessel. Makeup liquid is fresh incoming liquid in
the sense that it is not recycled from the reservoir.
[0017] We use the word "reservoir" for its dictionary meaning, "a
receptacle or chamber for storing a fluid." We use it to include
the term "vessel." "Reservoir" is used in the context of our
invention to emphasize that the flux stress device is immersed in
aqueous fluid within the receptacle or chamber, sometimes herein
called a vessel, capable of "storing" as that term is used in the
definition of "reservoir." That is, the reservoir serves as a more
or less continuously available source of hot water, steam or vapor,
which may be continuously or intermittently removed from it while
the source is continuously or intermittently replenished by makeup
liquid. While the aqueous fluid will pass through the cavitation
device or other flux stress device, and therefore may circulate
substantially continuously within the reservoir so that it will
circulate through the flux stress device to attain higher
temperatures, once the heated aqueous fluid is removed from the
reservoir either as hot fluid or steam, it does not return, as it
normally will be consumed or expended in any of many possible ways.
The reservoir containing the flux stress device may be called
either a water heater (aqueous fluid, or liquid, heater) or a
boiler, depending on the temperatures and pressures achieved, and
the purpose of the apparatus. However, the definition of "boiler"
includes a vessel used to heat liquid broadly--that is, it applies
to reservoirs, containers, and tanks wherein liquid is heated,
whether or not the liquid actually boils and/or whether or not
steam is generated. Further, the objective that the heated or
gasified liquid will be consumed or expended either continuously or
intermittently should not be read to mean that we rule out that
some portion of the fluid may be recycled after the fluid has left
the reservoir. And, we use the term "boiler vessel" to mean a
vessel for holding a liquid which may be boiled, but need not be.
Boiler vessels generally are constructed to provide for a specified
liquid level or range of levels, and a free space above the liquid
in which steam and vapor is contained, generally under pressure.
For many purposes, it will be desirable for the boiler vessel to be
a reservoir capable of handling pressures of up to 250 pounds per
square inch, and desirably at least 500 pounds per square inch.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a vertical section, in outline, of a boiler of our
invention.
[0019] FIG. 2 shows a construction similar to FIG. 1, from a
different perspective.
[0020] In FIG. 3, a variation is shown in which both the electric
motor and the cavitation device are immersed in the boiler vessel;
the rotor is mounted on a vertical axis.
[0021] In FIGS. 4a, 4b, 4c, and 4d, details of a cavitation device
rotor useful in our invention are shown.
[0022] FIG. 5 is a sectional view of a particular design for the
rotor of the cavitation device.
[0023] In FIG. 6, the boiler vessel wall is used for the
cylindrical housing of the cavitation device.
[0024] FIG. 7 shows a modification designed to circulate the
boiling fluid in a particular manner.
[0025] In FIG. 8, the use of a water brake heater within the
reservoir is shown.
DETAILED DESCRIPTION OF THE INVENTION
[0026] In FIG. 1, vessel 1 is capable of containing a desired
quantity of boiling water and steam as well as the equipment to be
described. It has a blowdown outlet 2 and a dry steam outlet 3.
Other conventional outlets and entrances, not shown, may be built
into vessel 1--for placing equipment, for repairs, for removal of
hot aqueous fluid other than blowdown, independently introducing
aqueous fluid, and any other desired purpose. On the lower part of
the left side of vessel 1, as depicted, is a cylindrical cavitation
rotor 4 having cavities 5 formed on its cylindrical surface. The
rotor 4 is designed to rotate within a hollow cylindrical housing 6
which may substantially surround the cylindrical surface of rotor
4. In this configuration, the circular face 7 of rotor 4 is not
enclosed--that is, it is in direct contact with hot or boiling
aqueous fluid 20. The rotor 4 is turned by engine or motor 9
mounted outside the vessel 1 and having a shaft 10 connected to the
rotor. The connection may be through a set of gears or other
mechanical power transmitting devices not shown. Shaft 10 passes
through the wall of vessel 1 to rotor 4. Also passing through the
wall of vessel 1 is a makeup feed line 11 coming from pump 12,
which may be preceded by filter 13. That is, the makeup fluid to be
treated may pass to filter 13 and then through line 15 to pump 12
for introduction to the boiler through feed line 11.
[0027] As explained above, rapid turning of the rotor 4 will cause
cavitation within the fluid, thereby elevating the temperature of
the fluid, ultimately to the boiling point. Pressure and
temperature regulators not shown may, at the operator's discretion,
establish boiling conditions other than atmospheric. Increasing the
pressure within the vessel 1 above atmospheric may beneficially
affect the cavitation process by enhancing the violence of the
mini-implosions taking place in the cavities, but the viscosity of
the fluid and the velocity of the outer surface of the rotor are
also important factors which the operator should consider. Reducing
the pressure below atmospheric (as by a vacuum pump for inducing
subatmospheric pressure) may help increase throughput and reduce
the energy requirements of the cavitation device. Other variables
of interest are the number and depth of the cavities and the flow
paths of the fluid in the particular construction of the boiler
vessel. Our basic invention, however, heats the fluid directly,
while immersed in the vessel, without flame or heat exchange
surfaces, and boils water in it for direct delivery of steam or
vapor. The vessel is able to contain and handle both the hot or
boiling water 20 and, in a free space above the water, steam
21.
[0028] In FIG. 2, the cutaway view of vessel 1 reveals the
uncovered and featureless circular face 7 of rotor 4 and
illustrates the proximity of cavities 5 to the interior surface of
housing 6. Circular face 7 need not be planar--to reduce drag or
for any other reason, it could be recessed. An alternative incoming
fluid feed line 16 enters the vessel 1 at port 17.
[0029] In FIG. 3, a variation is shown in which the motor 38 for
the cavitation device is immersed in the vessel along with the
cavitation device. The vessel 33 is represented as a typical tank
used at a production site for fracturing fluid in hydrocarbon
recovery, for example, a used fluid in need of a reduction in
volume, or a fracturing fluid deemed too cold for use, and simply
in need of heating. The cavitation device is shown in a horizontal
mode--that is, on a vertical axis, unlike FIGS. 1 and 2; the
cavitation device and the motor have been positioned in the tank
through manhole 37. Supports 30 hold and steady the housing 31
which substantially surrounds the cylindrical surface of rotor 32
in a manner similar to the housing and rotor in FIGS. 1 and 2.
Supports 30 do not impede the flow of fracturing, drilling, or
other aqueous fluid from under rotor 32. Aqueous fracturing fluid
already in the tank (vessel 33) flows through supports 30 and
enters the interior of rotor 32. As explained with reference to
FIGS. 4a-d and FIG. 5, and elsewhere herein, centrifugal force in
the rotating rotor 32 impels the fluid through radial channels
(FIG. 5) to the substantially cylindrical surface of rotor 32,
where it flows in the narrow space between rotor 32 and housing 31.
In the narrow space between rotor 32 and housing 31, the fluid is
subjected to the cavitation effect described elsewhere herein, and
undergoes a significant increase in temperature, exiting above the
rotor 32, where it circulates into the body of fluid 37 in the tank
or vessel 33. So long as the rotor rotates, fluid continuously
circulates and becomes elevated in temperature, ultimately, if
desired, making steam or vapor which is contained in the upper
region 35 of the vessel 33. A steam or vapor outlet or vent 36 is
connected at the top of the vessel for use of the steam or vapor as
needed or for release to the atmosphere. Where vessel 33 is not
used for boiling but simply heating a fluid as may be the case with
certain oilfield fluids otherwise ready for use, vent 36 may be
used simply to let the tank "breathe." Where the intent is to make
steam, vent 36 may be assisted by vacuum, and accordingly the
temperature of the steam or vapor may be lower than atmospheric
boiling. Any suitable level control, not shown, may be used to
balance the incoming fluid against the volume of steam or vapor
released or taken for a useful purpose, together with any blowdown
deemed necessary from a blowdown conduit not shown. The blowdown or
concentrate may also be used, for example to recover and recycle
chemicals used in an industrial process; for example to recycle
densifying salts used in completion or workover fluids in the oil
industry. Motor 38 and its electrical connections should, of
course, be watertight and insulated for immersed use.
[0030] FIG. 3 illustrates that a cavitation device may be used
simply to heat a fluid in a tank, and that the versatile cavitation
device can be readily placed in a tank and removed as desired. It
should be understood that the concept of immersing an entire
cavitation device including its motor is applicable to the vessels
described with respect to FIGS. 1 and 2--that is, motor 9 could be
submerged in vessel 1, makeup liquid could be introduced either
directly to the rotor of the cavitation device or simply though the
vessel wall, provisions could be made for blowdown, and all other
aspects of the invention are applicable whether the motor is within
the vessel or outside of it.
[0031] FIG. 4a is an outline perspective of a rotor useful in our
invention, and FIG. 4b is a lateral section of the rotor. They
illustrate that the numerous cavities 40, similar to cavities 5 in
FIG. 1, need not necessarily be aligned straight across the
cylindrical surface of the rotor 41. The cavities 40 are bored or
otherwise formed into the rotor 41. Also to be noted is that the
face of the rotor 41 is not featureless as is face 7 in FIG.
2--rather, it is somewhat hollowed and includes several apertures
43 arrayed around the central receptacle 42 for a shaft from the
motor (not shown). Apertures 43 may pass entirely through the
thickness of the rotor, as depicted. Also, the opening 44 of a
radial channel is seen in each aperture 43. As illustrated by
dotted lines in FIG. 4b, each radial channel 45 leads from an
opening 44 in an aperture 43, in particular aperture 43a, to an
outlet 46 on the cylindrical surface of rotor 41.
[0032] In FIG. 4c, Section A-A of FIG. 4b is shown. Radial channel
45 begins at opening 44 and terminates at outlet 46, in the center
of cylindrical surface 48 of the rotor 41. Aqueous fluid may enter
opening 44 from either side of aperture 43a to gain access to
opening 44. Radial channels 45 need not be restricted to their
central location within the rotor--that is, radial channels 45 may
have outlets 46 nearer the edge of the cylindrical surface of rotor
41 rather than being centrally located. Persons designing such a
rotor will probably wish to balance the number of channels on each
side of the rotor. In the lower side of Section A-A, as depicted in
FIG. 4d, will be seen two cavities 40a and 40b. In this variation
of the invention, the cavities comprise sections of relatively wide
diameter 49 and sections of relatively narrow diameter 50. Unlike
the radial channels 45, the cavities are "dead end," and do not
communicate with aperture 43b. Such dead end cavities, having wider
opening ends than closed ends, have been found to generate
cavitation more efficiently than bores of constant diameter.
[0033] Each of the apertures 43 may have an opening 44 leading to a
radial channel 45; thus in this variation, there are six such
radial channels, as there are six apertures. We do not intend to be
limited to six apertures or six radial channels. Any convenient
number of each may be used, and it should be understood that the
apertures, or some of them, need not pass completely through the
rotor 41. And, while the channels should pass from an opening near
the axis of the cylindrical rotor through the interior of the rotor
to exits on its cylindrical surface, they need not be oriented as
radii of a circular section of the rotor--that is, they may be
oriented at an angle, as will be shown in FIG. 5.
[0034] FIG. 5 is a central plane section, orthogonal to the axis of
its cylindrical shape, of one possible rotor 41, In this case,
there are eight apertures 60 in view, each opening to a channel 61.
Interior channels 61 are substantially true radials--that is, they
follow the paths of true radii of the cylindrical section, except
that they do not begin at the center of the rotor. Channels 62 are
set at an angle .theta. from a true radius, as seen by the dotted
lines and the symbol .theta.. Each of the channels 61 and 62 leads
from an aperture 60 to the cylindrical surface of the rotor. A
limited number of dead end cavities 64 are also illustrated,
showing a wide top and a narrow extension. Many additional cavities
and interior channels may be designed into the rotor. The wide
opening and portion of the cavities near the cylindrical surface,
and the narrower extension portions closer to the axis of the
rotor, may be varied in design. The angle .theta. may vary
considerably, from zero degrees to 60 or more degrees; angled
channels 62 need not be of the same angle. Shaft 65 is ready for
turning by a motor. The reader is reminded that FIG. 5 represents a
slice through the rotor, and that, depending on the particular
design, at least two other levels of channels and cavitities could
be seen (see FIG. 4a, for example). Indeed, the rotor can be
constructed to have numerous channel exits and cavities spread
across the cylindrical surface 48 of the rotor.
[0035] In FIG. 6, the vessel 70 has an internal diameter slightly
larger than the diameter of rotor 71, so that the cylindrical wall
of vessel 70 can act as the cylindrical housing in the
constructions shown in FIGS. 1 and 2. Rotor 71 is rotated by motor
72 through shaft 73. Rotor 71 is of a construction similar to that
of FIGS. 4a-4d and 5, and accordingly the incoming fluid from line
74 enters apertures not shown on the lower surface of rotor 71, is
thrust by centrifugal force through radial and/or somewhat angled
channels to the outlets 75 on rotor 71. As in FIGS. 4a-4d, rotor 71
has a plurality of cavities 76 which cause cavitation of the fluid
in the narrow space 77 between the rotor 71 and the wall of vessel
70, thus heating the fluid. From the space 77, the fluid may flow
either downwards and back into the apertures for recirculation and
further heating, or upwards into the boiling water holding space
78. Steam forming in the top of vessel 70 can be removed
initermittently or continuously through line 80. Blowdown or hot
liquid removal may be performed through line 79, and the boiling
and steam generation process may be modulated by any convenient
level control or other control devices, using flow readings from
the incoming fluid, the blowdown, and the steam output, as well as
conventional level viewer 81. All of the variations of the
invention shown herein may also utilize pressure, temperature and
other meter or transducer signals together with the flow readings,
level, valves, pumps, controllers and the like to regulate inputs
and outputs of the boiler vessel as desired. The vessel 70 need not
be shaped as shown, as substantially cylindrical, but could have
wider or narrower dimensions above or below the rotor 71, or both.
FIG. 6 is intended to illustrate that the wall of the vessel 70, or
a portion of it, can serve the function of the substantially
cylindrical housing 6 of FIG. 1 or 2, 31 of FIG. 3, 85 of FIG. 7,
or 22 of the water brake of FIG. 8, although for the last purpose,
additional provision should be made for circulation of the aqueous
fluid from below the water brake to above it, and from above to
below if desired.
[0036] In FIG. 7, the housing 85 for the cavitation device is seen
to have a vertical extension 86. Here also the rotor 87 is mounted
on a vertical axis, shaft 88 emanating from electric motor 89.
Incoming fluid in line 93 may be filtered in optional filter 94 and
pumped by pump 95 either to a featureless face on the rotor 87 as
in FIG. 2, or a face similar to that shown in FIGS. 4a-4d, or
anywhere into the boiler vessel, as through the side of vessel 90.
If the fluid is directed to the face of the rotor similar to that
of FIG. 2, the fluid is diverted directly to the side of vessel 90,
as indicated by the lower arrows 97. If it has apertures and
channels as illustrated in FIGS. 4a-4d, the fluid will be directed
through the rotor 87 and be thrust by centrifugal force out of the
channels (not shown) to outlets 91, where it will immediately
encounter housing 85. The fast-rotating rotor 87 will cause
shearing and tortuous flow between the surfaces of the rotor and
housing 85; when the fluid passes over one of the cavities 92, it
will attempt to fill the cavity, but will immediately be ejected by
centrifugal force, as previously explained, thus creating a
semi-vacuum, which is immediately imploded. The violence of such
cavitation converts the mechanical energy of the rotor into thermal
energy within the fluid, quickly elevating its temperature. In
either mode--that is, whether or not the fluid is able to pass
through one or more channels in the rotor, the fluid in vessel 90
substantially constantly circulates by entering the top of vertical
extension 86, as indicated by upper arrows 98. The fluid flows
downwardly in extension 86, then to the extremities of the rotor 87
within housing 85, where it is again subjected to the heating
action of cavitation. If salts and/or solids accumulate in the
heated fluid, a blowdown may be conducted as desired through
blowdown line 96. In some instances, the blowdown concentrate will
contain valuable constituents which may be recovered in a known
manner for recycling or other uses. Motor 72 in FIG. 6 and motor 89
in FIG. 7 could alternatively be located within the boiler vessel,
as illustrated by the embodiment of FIG. 3.
[0037] FIG. 8 is a section of a vessel 1 containing a water brake,
sometimes known as a dynamometer or a water brake dynamometer. Such
a device is within our definition of a flux stress device, as
indicated above. In FIG. 8, the depiction of the water brake is
modified from an illustration in Wikipedia. The water brake
comprises a rotor 23 within a stator 22 desirably fixed within the
vessel 1 by supports or struts not shown. Rotor 23 is fixed to a
shaft 10 which is rotated by a motor not shown, outside the vessel,
although, as explained elsewhere herein, a submersible motor may be
used within the vessel. Annular cavities 24 and 25 are defined by
the stator 22 and rotor 23. Annular cavity 24 is filled with
aqueous fluid entering from outside the vessel through conduit 26.
Annular cavity 25 is filled with aqueous fluid 20 from inside the
vessel 1, entering through port 28. Either or both annular cavities
may be filled with aqueous fluid either from outside the vessel or
from inside the vessel; if both obtain fluid from inside as through
port 28, a feed line such as feed line 16 in FIG. 2 may be used to
place makeup fluid in the vessel 1 either continuously or
intermittently; such a source of fluid is recommended in any event.
Rotor 23 is caused to rotate on shaft 10 within the stationary
stator 22, causing considerable turbulence within the annular
cavities 24 and 25, and also causing the fluid to be ejected from
the annular cavities by centrifugal force, through cavity exits 27
near the outer edges of the cavities. Aqueous fluid thus circulates
from the entrance points near the axis of rotation of the rotor
(conduit 26 and port 28) to cavity exits 27 near the outer edge of
the rotating rotor, becoming heated from the agitation and
turbulence caused by its position between the rotating rotor 23 and
the motionless stator 22. The more or less constant flow of fluid
into and out of the water brake and the differing temperatures of
the entering and exiting streams of fluid cause a constant
circulation of fluid within the vessel 1, which provides a means
for control of the temperature in the vessel. A level tube 81 may
be used to monitor level, and various thermocouples transducers,
valves, flow meters, pressure monitors and controls, and other
devices not shown may be used to achieve the desired temperatures
and pressures, including pressures lower than atmospheric in the
free zone 21 above the fluid 20 if so desired. Steam or vapor may
be removed through outlet line 3 and blowdown conducted through
blowdown line 2.
[0038] Therefore, it is seen that our invention comprises a
reservoir including a flux stress device, which may be a cavitation
device, within the reservoir, which may be a boiler vessel. The
cavitation device may comprise a rotor for immersion in liquid, the
rotor comprising a body having a substantially cylindrical surface
and two faces, the body having a central opening on at least one
face for receiving a rotatable shaft for rotating the rotor and a
plurality of channels for admitting liquid when the rotor is
immersed in the liquid and transporting it to the substantially
cylindrical surface, and a plurality of cavities on the
substantially cylindrical surface. A submersible electric motor may
be used, to place the entire flux stress device, including the
motor, in the reservoir. In a particular variation, our invention
is a boiler apparatus comprising a substantially cylindrical vessel
having a substantially cylindrical interior surface, and a
substantially cylindrical cavitation rotor within the vessel, the
substantially cylindrical rotor also having a substantially
cylindrical surface, the cylindrical rotor surface having a
diameter slightly smaller than the interior surface of the
substantially cylindrical vessel, the rotor surface and the
interior surface being substantially concentric. And, our invention
includes a method of substantially continuously or intermittently
heating an aqueous fluid comprising placing the aqueous fluid in a
reservoir such as a boiler vessel and causing cavitation or other
flux stress within the aqueous fluid in the reservoir, which may be
substantially continuously or intermittently replenished. The
reservoir may be a tank and the aqueous fluid may be an oilfield
fluid such as a fracturing fluid.
* * * * *