Note: Descriptions are shown in the official language in which they were submitted.
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DIRECT CONTACT
ROTATING STEAM GENERATOR
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to an apparatus and
method to
produce steam, gas, and solid waste without waste water from low quality water
and low quality
fuel by direct contact in a rotating pressurized vessel.
Description of Related Art
Generally, steam production facilities are divided into two main types: direct
contact
steam production facilities, and indirect steam facilities steam production
facilities. In direct
contact steam production facilities, water is mixed with hot gases to produce
steam by direct heat
exchange between the water and the gases to provide a mixture of steam and
gas. In an indirect
steam production facility, the heat that is required to produce the steam from
the water is
provided through a metal wall, typically a steel wall, that prevents the
mixture of the water and
hot gases.
Indirect contact steam generation is widely used for steam production. The
devices vary
from steam drum boilers to Once-Through Steam Generators (OTSG). The heat
exchange can be
by radiation, convection or both.
The direct-contact steam generators are much more limited in use than the non-
direct
contact steam generator. One of the proven applications for the direct contact
steam generation
process is enhanced oil recovery (EOR), wherein steam and flue gas (mainly
COz) mixtures are
injected into a heavy oil reservoir to increase oil mobilization in heavy oil
production.
The main characteristic of the direct contact steam generator is that the
produced steam
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contains impurities, such as combustion products (mainly gases and possible
solids) that were
burned during production of the steam. Those gases are mainly carbon dioxide
and nitrogen,
when air is used for the combustion process. Additional gases can be present
in smaller
percentage such as CO, SOx, NOX and other gases. Due to the presence of
combustion gases, the
steam produced by direct contact will be usecl in open circuit systems or in
systems that can
handle the impurities in the steam.
In recent years, the advantages of direct contact steam generators have become
more
obvious due to increased awareness of the need to reduce greenhouse gas
emissions. Direct
contact steam generators are devices preventing such greenhouse gas emissions,
for example, by
injecting COz. In the example of the direct contact steam generator for heavy
oil recovery
applications, portions of injected harmful CO-2 gas will permanently stay
underground and will
not be released into the atmosphere.
The need for the present invention is driven by the challenges facing the
heavy oil
production industry involved with enhanced oil recovery (EOR), and in
particular, steam assisted
gravity drainage (SAGD) and cyclic steam stimulation (CSS). The disadvantages
of the prior art
indirect steam generation prevented it from becoming the preferred commercial
solutions for
SAGD and CSS EOR. As a result, indirect steam generator, mainly OTSG and steam
drums, are
used commercially as the alternative. In the prior art, the systems of both
direct and indirect
steam generators have a continuous flow of water through the system that
maintains a solids
concentration at acceptable levels in the steam vessel. Additionally, the flow
of water controls
solids build-up in the steam reactor for direct generators and in the drum or
on the tubes for
indirect generators. The dissolved solids concentration increases downstream
from the steam
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generator as more water transitions from liquid to gas as the process moves
along. The water
with through the most concentrated solids is rejected from the steam
generation process to
crystallized treatment facilities or disposal wells. Thus, there is a need to
eliminate the need for
these additional treatment facilities to convert the waste into solid form.
The prior art of down hole direct contact steam generators do not disclose
continuous
water flow through the system to remove the solids. However, the generated
solids are released
to a reservoir. These prior art systems are limited to the use of fuels that
are clean fuels as well as
the need for clean water, since impurities and generated solids can block the
reservoir.
[1] There is also a need to utilize low quality carbon fuel such as coal,
coke, and asphaltin as
the energy source for the steam production in the heavy oil production
industry to replace the
widespread use of natural gas. Natural gas is a, clean and valuable resource
that, from a public
perspective, should not be used for steam production in heavy oil extraction.
This clean resource
should be preserved and used for other valuable processes.
There is a major need to produce steatn in a thermally efficient way and to
inject the
generated CO-2 back into the reservoir.
There is a need to use low quality water that contains solids like silica,
clay and other
minerals from tailing ponds, dissolved solids and organic emulsions, like tar
and heavy oil based
materials. There is now a need that for low quality water to be used directly
with minimal
additional treatments prior to steam production.
There is a need to extract the continuously produced waste in a dry solid form
that can be
efficiently and economically disposed of in a landfill.
Above all, there is a need for an apparatus and a method that will enable
fulfilling the
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above mentioned needs in a simple and reliable way.
Various patents have issued that are relevant to the present invention. For
example, U.S.
Patent No. 2,916,877, issued on December 15, 1959 to Walter, teaches a
pressure fluid generator
which utilizes direct contact heat transfer. The pressure fluid generator is
in the form of an
elongated combustion chamber. A coolant in heat exchange relationship is
injected into the
combustion chamber to form with the combustion products therein as a gas and
superheated
vapor working mixture at a relatively high temperature and pressure. Some
embodiments
include in -line soot filters and circulated water, and the fuel is
hydrocarbon gas.
U.S. Patent No. 4,398,604, issued on August 16, 1983 to Krajicek et al.
describes a
system for above-ground stationary direct contact horizontal steam generation.
The method and
apparatus produces a high pressure thermal vapor stream of water vapor and
combustion gases
for recovering heavy viscous petroleum from a subterranean formation. High
pressure
combustion gases are directed into a partially water-filled vapor generator
vessel for producing a
high pressure stream of water vapor and combustion gases. The produced solids
are continually
removed with reject water.
There are also patents related to applications in heavy oil production. U.S.
Patent No.
4,463,803, issued to Wyatt on August 7, 1984 describes a system for down-hole
stationary direct
contact steam generation for enhanced heavy oil production. The method and
apparatus
generates high pressure steam within a well bore. The steam vapor generator is
constructed for
receiving and mixing high pressure water, fuel and oxidant in a down-hole
configuration. The
produced solids are discharged to the reservoir.
Various patents have disclosed rotational elements in a steam generator. U.S.
Patent No.
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1,855,819, issued on April 26, 1932 to Blomquist et al. describes a rotary
boiler, where the
pressure chamber is rotating inside the combustion area while producing the
steam in an indirect
heat exchanger. British patent No. 0 328 339, issued on May 1, 1930 to Kalabin
teaches a direct
contact steam generator with a rotating pressure vessel. The gases flow to a
rotating chamber
where they are mixed with air and completely burned. Water covers the walls of
the rotating
chamber by centrifugal force of the rotating chamber, exposing the water to
the gas combustion.
Russian Patent No. 2 285 199, issued on December 12, 2004 to Krajazhevskikh,
describes a
steam generator with a rotating chamber with cap-shaped hollow portions.
Combustion gases
flow between the rotating chamber and a stationary chamber for indirect heat
exchange.
Japanese Patent No. 581 153 576, issued on September 9, 1983 to Shirou
discloses a steam
generator with a horizontal rotating heater filled with ceramic balls.
Combustion gas is fed to the
rotating heater, where the ceramic balls are heated. Solid materials formed
into powders or
granules are mixed with the heated balls and transferred through a pipe to a
stationary boiler.
Steam is generated through indirect heat exchange between the pipe and water.
It is an object of the present invention to provide an apparatus and method
for the
production of high pressure, dry super-headed steam and a combustion gas
mixture using direct
contact heat transfer between available water and fuel in a rotating reactor.
It is another object of the present invention to provide an apparatus and
method where the
waste solids generated by combustion and steatn generation are driven by
gravity to regenerated
surfaces at the bottom of the apparatus. These regenerated surfaces are freely
rotating spherical
bodies that partly fill a rotating vessel of the apparatus. The spherical
bodies remove deposits
and build-ups of these waste solids.
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It is another object of the present invention to provide an apparatus and
method where the
waste solids are separated and removed from the main flow of the steam and gas
mixture without
decreasing the steam-gas mixture pressure and temperature.
It is another object of the present inveution to provide an apparatus and
method that
produces steam from low quality tailing pond and reject water containing high
levels of
dissolved inorganic solids or organic solids, wherein all water is converted
to steam and no liquid
is discharged from the apparatus.
It is another object of the present invention to provide an apparatus and
method that
produces steam from low quality fuel containing inorganic impurities like
coal, coke, asphaltin
or any other available carbon based fuel, wherein the combustion byproducts of
this fuel are slag
and ash in solid form.
It is another object of the present invention to provide an apparatus and
method that
minimizes the amount of energy used to produce the mixture of steam and gas
that is injected
into an underground formation to recover heavy oil.
It is a further object of the present invention to provide an apparatus and
method where
the low quality water is converted to steam, without any wastewater flow. The
concentration of
inipurities increases to a maximum through the process of a direct contact
steam generator, when
the impurities can be removed as solid waste.
It is another object of the present invention to provide a method that
produces high
temperature steam and gas in a rotating, self cleaning steam generator. Solids
are removed in dry
form from the hot gas flow. The hot gas flovv and the remaining solids are
injected into the
vessel, where the solids are scrubbed by water. A saturated wet steam is
produced. The slurry of
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solids and water continue to pass back and recycle through the rotating steam
generator. The
saturated wet steam-gas mixture is heated by heat exchange with the hot gases
leaving the
rotating steam generator to produce super-heated dry steam that is injected
into an underground
formation to recover heavy oil.
BRIEF SUMMARY OF THE INVENTION
The main advantage of the present invention over the direct contact steam
generation of the prior
art is the ability to use low quality water and fuel, the ability to avoid
liquid discharge waste, and
the ability to remove a solid waste byproduct, when all water has been
converted to steam and
fuel has been converted to gas. In the present invention, solids concentration
increases inside the
steam generator, where it reaches a maximum concentration as a solid. The
extraction of the
produced solid waste as part of the steam generation process is advantageous
as it eliminates the
need for additional treatment facilities to treat the water prior to use in
the steam generator, to
convert a wastewater flow into solid form and to reduce its volume (like
evaporators and
crystallizers) . The disposal of solid waste in landfills is more economic and
environmentally
friendly.
Furthermore, the proposed apparatus and method allows direct use of coal for
heavy oil
recovery, eliminating the burning of natural gas to produce steam and the
converting of coal to
methane for natural gas in heavy oil recovery. The present invention minimizes
the use of the
clean and valuable natural gas resource by replacement with coal or other low
quality fuels.
Additionally, harmful CO-2 gas emissions are injected into the underground
reservoir and out of
the atmosphere.
The present invention is a reaction chamber apparatus and the method for its
use for
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producing a steam and CO2 mixture without generating liquid waste. The
apparatus includes a
rotatable vessel in a direct contact steam generator. The rotatable vessel has
a combustion
section and a steam producing section and is partially filled with spherical
bodies. The
combustion section and the steam producing section are partially separated by
a partition or by
location in the rotating chamber. A homogenizing section is located at an end
of the steam
producing section opposite the combustion section. The homogenizing section
may have at least
one partition wall guiding the flow of gases. The vessel has at least one
opening or a fixed
collector at the bottom of the vessel to allow for the discharge of solids.
In an alternative embodiment of the present invention, the reaction chamber
apparatus
includes a fixed combustion vessel and a rotatable steam generating vessel.
The combustion
vessel and steam generating vessel are in communication with one another. The
steam generating
vessel is partially filled with spherical bodies. The steam generating vessel
has at least one
partition wall guiding the flow of gases. Both the steam generating vessel and
the combustion
vessel have a solids discharge outlet at the bottom of the vessels. The solids
discharge outlet is
sized such that the spherical bodies will not be discharged from the interior
of the vessel.
The present invention is also a method for producing a steam and CO2 mixture,
comprising the steps of mixing a low quality fuel with an oxidation gas,
combusting the mixture
under high pressure and temperature in a vertical rotating drum with spherical
bodies to remove
the solids resulting from the combustion step, and injecting low quality water
containing organic
or inorganic materials so as to control combustion temperature and to generate
steam in the
rotating drum. The waste solids generated by the combustion and steam
generation are driven by
gravity to regenerated surfaces at the bottom of the rotating drum. The
regenerated surfaces are
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the freely rotating spherical bodies partially filling the rotating vessel.
The spherical bodies
grind solids deposits and build-ups in the rotating chamber. The fuel is
selected from a group
consisting of coal, heavy bitumen, vacuum residuals, asphaltin, and petcoke.
The oxidation gas
is selected from a group consisting of oxygen, oxygen-enriched air, and air.
The spherical
bodies improve mixing and heat transfer. Some of the oxidizer is supplied
separately with the
low quality water, creating a secondary exotherrnic reaction with partially
combusted gases.
The step of combustion includes converting the fuel to a gas and byproducts in
solid or
liquid form, such as slag, fly ash and char. The step of steam generation
includes converting
water from a liquid phase to a gas phase, the gas phase containing steam, CO'?
(and possibly other
gases like S02) Solids are also separated from the gas phase.
The method of the present invention also includes the steps of cleaning the
gas and the
steam from fine solid particles in a separator, mixing the gas and steam with
water of high
temperature and pressure so as to produce a saturated wet steam and gas
mixture, scrubbing any
remaining solids from the gas, separating the liquid phase from the gas phase,
and recycling the
water with the scrubbed solids back to the combustion chamber. In the event
that the gas
contains sulfur, and if there is a need to reduce the amount of sulfur, the
process can include
adding lime or other chemicals during the step of scrubbing and then reacting
the lime or
dolomite with the sulfur.
The saturated steam and gas mixture are heated in a heat exchanger with the
hot gas phase
leaving the combustion chamber to generate super-heated steam and gas,
preventing
condensation on pipes of the apparatus.
Additives can be injected into the gas phase to protect the pipe from
corrosion. The
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pressure of the clean wet steam is reduced to an injection pressure. The
pressure of the dry
steam and gas mixture is between 800 and 10,000 kpa The temperature of the dry
steam and gas
mixture will be between 170 C and 650 C. The super heated dry steam and gas
mixture can be
injected into an underground reservoir through a vertical or horizontal
injection well, for
example in EOR.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
FIGURE 1 is a schematic view of a reaction chamber apparatus of a rotating
direct contact
steam generator of the present invention.
FIGURE 2 is a schematic view of the direct contact rotating steam generator of
the
present invention with partitions.
FIGURE 3 is a schematic view of anotlier direct contact steam generator with
partitions
to separate the combustion from the steanl generation, increasing the
effectiveness of the mixture
by forcing the flow through an internal medium.
FIGURE 4 is a schematic view of an alternate embodiment of a reaction chamber
of the
direct contact steam generator with two separate rotating vessels, one for the
combustion and the
second for steam generation.
FIGURE 5 is a schematic view of another alternate embodiment of a reaction
chamber of
the direct contact steam generator with a fixed combustion chamber with a
rotating steam
generator.
FIGURE 6 is another schematic view of the reaction chamber of the direct
contact
rotating steam generator, wherein the generator is connected to a solids
separation and removal
section and combined with a wet solid scrubbing section, the saturated mixture
being heated to
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produce a superheated dry mixture.
FIGURE 7 is a schematic view of still another alternate embodiment of the
reaction
chamber of the direct contact rotating steam generator with a fixed pressure
vessel and a rotating
internal enclosure.
DETAILED DESCRIPTION OF THE INVENTION
FIGURE 1 shows the reaction chamber apparatus of a high-pressure direct
contact steam
generator of the present invention with a horizontally-sloped pressure vessel
17, partly filled
with spherical embodiments 16 that are free to move inside the vessel. The
vessel 17 is under
pressure and is continually rotating or rotating at intervals. At a high point
14 of the sloped
vessel 17, the fuel, oxidizer and water are injected. The fuel can be coal
slurry, petcoke, or
hydrocarbons such as untreated heavy low quality crude oil, VR (vacuum
residuals), asphaltin,
"green" petcoke, or any available carbon fuel. The oxidizer is a gas (oxygen,
enriched air or air)
mixed with the fuel in the combustion area 11 of the vessel 17 of the high-
pressure direct contact
steam generator. The temperature in the combustion area 11 is more than 900 C
to ensure full
combustion of the fuel. Water is injected into the exothermal reaction volume
in the combustion
area 11 to maintain a controlled high temperature, preventing damage to the
facility while
achieving a full oxidation reaction of the fuel.
Due to the high temperatures in the combustion area 11, melted byproducts are
continually created. For example, a fuel like coal would cause slag, ash, and
soot byproducts.
The slag settles on the bottom of the vessel 17 due to gravity. The bottom of
the vessel is partly
covered with the free moving spherical embodiments 16. The spherical bodies 16
provide an
exposed regenerated surface area for exposing the slag and other combustion
solids. The
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temperature of the spherical bodies 16 is lower than the reaction temperature.
The temperature of
the spherical bodies 16 is also lower than the slag and ash melting
temperature, preferably less
than 800 C at which the slag and ash are solids. The ash and solid deposits
left from the reaction
(mainly silica, heavy metals etc. that result from the specific type of fuel
in use) are settled on the
exposed surfaces, mainly the surface area of the spherical bodies 16. Due to
rotating movement,
the spherical bodies 16 regenerate their surface area by removing and grinding
deposits from the
vessel 17 walls and each other to form smaller particles of solids to be
removed from the reactor
vessel 17.
The spherical bodies can be hollow with less weight because the grinding is
needed only to
regenerate their surface and to mobilizes the solid generated waste. The
additional grinding of
the produced solid waste is a by-product and it is mot require if the solid
particle size is less then
6mm. The spherical bodies can also decrease in size from the combustion
section to the
homogenizing section to improve the mixing of the flow and the internal heat
transfer.
The steam is actually produced in the combustion section 11 and in the steam
production
section 12, where low quality water is injected to produce steam. The amount
of injected water is
controlled to produce steam where the dissolved solids remain solids and
liquids become gas.
Additional chemical materials can be added to the reaction, preferably with
any injected water.
For example, limestone slurry can be added to the low quality water. The steam
production
section 12 contains similar spherical bodies 16 that are present in the
combustion section 11.
When the liquids (primarily water) evaporate, the solids settle on the
internal exposed surfaces,
mainly on the surface area of the spherical bodies 16. The rotational movement
regenerates
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surface area of the spherical bodies by removing the solid deposits therefrom
and from the
vessels walls.
The mixture of gas, solids and remaining liquid move to the homogenizer
section 13 in
the vessel 17, where the heat transfer is completed to provide a homogenous
mixture of gas and
grinded solids. All the remaining liquid transitions to gas, and the remaining
solids are moved to
a discharge point 15. The solids at the discharge point are released from the
vessel 17 at high
teniperature and pressure for further processing, such as separation and
disposal. It is possible to
supply access water in sections 11 and 12 to maintain the solids created both
from the
combustion and the water evaporation in concentrated and viscous slurry form
with saturated
steam at the working temperature and pressure.
FIGURE 2 shows a reaction chamber apparatus of a rotating steam generator that
includes partial partitions. The fuel 214 can be coal slurry, hydrocarbons
such as untreated heavy
low quality crude oil, VR (vacuum residual), asphaltin, petcoke or any
available carbon fuel. The
oxidizer gas 215 can be oxygen, enriched air or air. Steam 216 can be injected
through the burner
218 during start-up. The water 217 is injected to the combustion chamber 21 to
control high
temperatures, preventing structural damage. The water, injected to the burner
218, is relatively
high quality water that will not damage the burner 218. The burner 218 is a
commercially
available burner, such that the required injected water quality can be known.
The fuel 214 and
oxidizer 215 are injected to the combustion chamber 21 through pipes 210 that
are connected to
the burner 218. Both pipes 210 for the fuel 214 and oxidizer 215 and pipe 211
for the low quality
water are fixed and do not rotate while the vessel rotates.
The connection 212 seals the pipes 210 and 211 connected to the reactor as the
pressure
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inside the combustion chamber increases as required for the production of
steam. These rotatable
and sealed connections 212 and 29 are commercially available. To avoid
leakage, high quality
clean water can be used as part of the seal for the high pressure sea] medium
and cooling fluid
when water enters the reactor. This seal has no effect on the steam generator
performance.
The temperatures in the combustion section 21 are significantly higher than
temperatures
experienced during the rest of the steam generation process because the
temperatures are driven
from typical fuel combustion (and not from the steam generation). The
combustion temperature
is more than 900 C and preferably in the range of 1200-1300 C for low slag
fuel. The
temperature minimizes the amount of unburned carbons in the slag for any
particular fuel in use.
The combustion section 21 in the vessel is coated with thermal resistance
material 24 that can
withstand these high temperature conditions. Low quality water 213 with high
solids
contamination, like silica clay, totally dissolved solids, and possibly
organic materials, such as
tar, heavy oil, biologically-contaminated sewage and any similar waste water,
is injected through
pipe 211 to injectors 219 for injection around the combustion reaction zone.
The bottom of the vessel is partially filled with free rotating spherical
bodies 28. The
solids are attracted to the spherical bodies 28 due to mass and gravitational
force. The water
reduces the temperature of the internal spherical bodies 28 to less than the
temperature required
to solidify the slag, typically less then 850 C. "The low quality injected
water 213 is evaporated
and reduces temperature of the spherical bodies 28 to less then 850 C. The
steam is generated in
the rotating reactor where the spherical bodies 28 grind the remaining solids
and maintain the
clean surface of the vessel, where liquids transition into gas and solids are
ground into particle
waste.
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At the back of the primary combustion and steani generation section 22, there
is a
separation wall 25 that forces the flow of gases and fluids to go around it.
At the bottom of the
vessel 22, there are the same spherical bodies 28 that grind the solids and
work as a heat
exchanger.
In section 23 of the vessel, there are partition walls 27 that force the flow
of the gases and
the fluids to go around and through the spherical bodies 28 to convert all the
liquid to gases and
grind the solids. The mixture of the gas, mainly steam, CO2, and possibly
smaller percentages of
other impurities, and the remaining solids are discharged at the other side of
the vessel through
separation 220, allowing free flow while maintaining spherical bodies 28 in
the vessel.
FIGURE 3 shows a reaction chamber of a rotating steam generator having
separate chambers
with opposite openings. The fuel 322, oxidizer= 323, steam 324, and high
quality water 325 are
injected through the rotating seal to the burner 37 located in the combustion
chamber 31. The
rotating seal is composed of fixed section 310 and rotated section 39 that
rotates with the vessel.
The combustion occurs outside burner 37 in the combustion chamber 31. The
combustion
chamber is thermally protected by a protection layer 35. The bottom of the
combustion portion is
partly filled with spherical bodies 36 that are freely rotating on the vessel
bottom. To maintain
the temperature under control, high quality water 325 is injected through the
burner. To generate
the steam, low quality water is injected directly to the steam generated
chamber 32. The amount
of oxygen 323 injected through burner 37 is less than the amount required for
full combustion.
The partial combustion is conlbined with the injected high quality water 325
or the water in the
fuel slurry. If the fuel is in the form of a slurry, the temperature in the
combustion chamber 31 is
maintained at an acceptable level for structural integrity of the vessel.
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The combustion section is separated from the steam generator section by a
separation
partition 321. Low quality water 326 for steam production is injected through
this separation
partition 321 directly into the steam generation chamber 32 through a fixed,
non-rotating pipe 38.
Oxidizer 323 is also injected into the steam generator chamber 32 through
discharge 315. The
oxidizer burns the carbon monoxide and the renlaining carbon to produce mainly
carbon dioxide
and steam. The vessel is divided for internal chambers 33. Each chamber
section in the vessel
can be accessed for maintenance through flanged openings 34 from the outside
of the vessel. In
each separation wall, there is an eccentric opening near the vessel wall 314.
These openings are
in an opposite direction (180 degrees) from each other, forcing the sludge to
flow through the
spherical bodies 36 for mixture, heat transfer, scrubbing and removing the
generated solids. The
openings 314 are arranged in a way that forces gas and liquid to flow through
the spherical
bodies 36 that partly fill the separate sections of'the vessel.
The spherical bodies 36 are different in material and shape within each
section. Within
the combustion section, the spherical bodies 36 will be medium sized and made
from high
temperature resistant material. This material can be ceramic or alloyed steel
that can also have
catalytic characteristics. The spherical bodies 36 at the first steam
generation chamber are of a
relatively large size to allow the hot gases and liquid to mix. The spherical
bodies 36 at the
following chambers 33 are smaller in size and can be made from hollow carbon
steel.
Each chamber section is accessible from the outside through openings 34. To
force the
flow through the chambers, there are two eccentric openings 314 from both
sides. Those
eccentric openings 314 are close to the vessel walls and allow the solids to
flow near the bottom
of the vessels during rotation. The discharge from the vessel is through pipe
317 centrally located
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at the back of the vessel. The hot gas and solid mixture flows through the
rotation seal connector
310 to pipe 3 16 for further processing.
Figure 4 shows a reaction chamber with a complete separation of the combustion
vessel
and the steam production vessel. The advantage of such an arrangement is the
separation of
solids resulting from the combustion of the fuel and solids remaining from the
sludge water
turning to steam. Fuel 43 and oxidizer 44 injected through the rotating sealed
connection 46 to
the burner 49. The combustion reactor 41 contains spherical bodies 410 that
remove the solid
deposits from the vessel walls and grind and mobilize the remaining solids. To
reduce the
temperature, the oxidizer 44 can be reduced to generate a partial oxidation
reaction. High quality
water 45 may be injected to the vessel 41 to reduce the temperature. The build-
up of grinded
solid deposits can be removed through opening 411 in the vessel. The removal
can be done
during shut-down intervals, when the inside pressure is dropped and where the
ground solids
from the combustion section are collected in collector 412. The temperature of
the produced gas
leaving the reactor 41 is in the range of 500-850 C.
The hot gases flow to the steam generator section 42. Low quality water 413
and oxidizer
44 are injected through rotating sealed connection 414 to the steam generation
section 42. The
steam generation section 42 contains partitions 417 that direct the flow
through the spherical
bodies 416. The solids from the low quality water 413 are removed in a similar
way as from the
combustion section 41 through an opening 419 in the last section 418 and a
collector 420 where
they are collected separately from the combustion solids.
If the fuel contains a significant amount of heavy metals that can be
recovered, or if special land-
fill disposal is required and if, at the same time, the water contains
significant amount of solids,
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there might be an advantage to using the arrangement described in FIG. 4 for
separating the
combustion remains.
FIGURE 5 contains a reaction chamber apparatus for a direct contact steam
generator with a
fixed combustion vessel 51 connected to a rotating steam generator 52. Fuel
54, oxidizer 55 and
water 56 are injected to a combustion vessel 51,. Solids resulting from the
combustion 518 can be
removed. The combustion in combustion vessel 51 can be a partial combustion to
reduce the
temperature of the produced gases 57. The produced hot gas mixture is at
temperature of 500-
850 C. The mixture flows through the rotation connection 59 to the rotating
steam generator 52.
Low quality water 53 is injected into the first chamber 510. Oxidizer 55 is
also injected to this
first chamber 510 where it fully reacts with the partial combusted gases from
519 to produce
steam. Section 52 contains spherical bodies 511 that are free to rotate. By
rotation, the spherical
bodies 511 grind and remove the generated solids, improving heat transfer. The
openings
between the partitions 514 are located near the vessel wall at opposite sides
to force the flow
through the spherical bodies 511 that partly fill the volume and to minimize
the solids build-up.
The discharge from the last vessel section is through pipes 515 that are fixed
to the rotating
vessel and connected in four locations near the vessel wall.
The rotating connector 516 and fixed pipe 517 are connected to the rotating
vessel. The
rotating connector 516 connects the lower pipe 515 by exposing the lower pipe
515 to a round
disc with slot 519 that is connected to pipe 517. Due to this arrangement, the
flow from the
rotating vessel is only from its lowest part which efficiently and continually
removes the
generated solids.
FIGURE 6 shows a reaction chamber apparatus of a direct contact rotating steam
generator with
CA 02626416 2008-07-25
solids separation. Fuel 616 (possibly in slurry form), oxidizer 617 (such as
oxygen enriched air)
and high quality water 618 are injected through rotating connection 62 to high
pressure burner
614 located inside a steam generation rotation reactor 63. The pressure in the
steam generator
reactor is in the range of 800kpa- 10000kpa, preferably in the range of
3000kpa-4000kpa. The
temperature in the combustion reaction area is in the range of 900-2500 C,
more preferably in
the range of 1300-1800 C. The combustion is separated from the rotating steam
generator by a
sloped sleeve 630. The sleeve 630 is maintained at a high temperature beyond
the slag and ash
melting temperature where the melted slag and ash flows out from the sleeve.
T'he combustion
reaction in the sleeve 630 can be a full reaction where mainly COz is
produced, or partial
combustion where mainly CO is produced. The level of combustion will be set
according to the
fuel and water in use and the working conditions to prevent over-heating of
the combustion area.
If partial combustioil is used, oxygen or enriched air will be injected with
the low quality water
619 through injectors 615.
Low quality water 619 is injected into the vessel through injectors 615 to the
boundaries
of the combustion reaction zone from sleeve 630, where steam is generated,
while the
temperature is reduced to solidify the created slag and ash. This low quality
water 619 that is
injected separately from the burner 614 is not intended to reduce the
combustion zone
temperature but to protect the structure of the steam generator and to prevent
melted slag, ash,
and soot particles from sticking to the internal elements with a permanent
bond that cannot be
ground off by the free rotating spherical bodies 613 moving in the reactor.
The bottom of the vessel is partly filled with spherical bodies 613 that are
freely rotating.
Separation partition 65 at the back of the vessel keeps the spherical bodies
away from the back
CA 02626416 2008-07-25
discharge section 629. The gas and solids flow to the back section 629 through
radial openings
612 in separation wall 65 that are close to the vessel wall, preventing the
solids from build-up in
the steam generation section 63. The first gas-solids separation in the
process is inside the
rotating section into two gas flows: flow 69 is a lean solids gas and flow 610
is a rich solids gas.
Collector 611 is fixed, not rotating with the vessel. The collector 611 is
installed close to the
bottom of section 629 of the vessel in close proximity (within a few inches)
to the rotating vessel
bottom where the solids are collected from the rotating vessel bottom,
resulting in a rich solids
flow 610.
A single or set of fixed solid separation cyclones are installed in the upper
section of
section 629 where the lean solid flow is directed out from the rotating
reactor and the solids
directed to the bottom section to the solids collector 611. The temperatures
of the discharged rich
solids gas stream 610 and the lean solids gas stream 69 are in the range of
170 C and 650 C,
more preferably in the range of 300 C-450 C'. The rich solids stream 610 flows
to external
secondary solids separation 624 where the solids 625 are separated by a
cyclonic separator,
centrifugal separator, mesh separator or any other known commercially-
available separation
system, and disposed in a land-fill or any other method. After separation the
lean solid stream
610 is injected into vessel 620.
The lean solid stream 69 flows through superheated steam heat exchanger 622
and is
injected into vessel 620. Vessel 620 is maintained at a high pressure 800kpa-
10000kpa,
preferably in the range of 3000kpa-4000kpa, slightly less then the pressure at
the rotating reactor
to allow the flow. It is partially filled with water to wash the remaining
solids and possibly to
react with gases like sulfur gas, if required. Fresh make-up water 627 is
continually injected into
CA 02626416 2008-07-25
the vessel to maintain the scrubbing liquid level. Limestone, dolomite,
magnesium oxide or other
materials can be injected to the vessel 626 in a slurry form. The solids
concentrated reject water
is continually removed from the bottom of the vessel 623 where it is injected
and distributed,
possibly with additional low quality water, back to the rotating steam
generation reactor 615. The
vessel produces saturated clean wet steam and gas mixture 621. The wet steam
flows through
heat exchanger 622. It is heated by the lean solid stream 69 flow and becomes
superheated dry
steam / gas mixture 628. This high pressure product can be injected into an
underground
formation to enhance oil recovery while minimizing condensation corrosion
problems.
FIGURE 7 shows a reaction chamber for rotating steam generation with an
externally
fixed horizontal pressure vessel with external solids separation. An
internally mounted rotating
enclosure is placed inside the reaction chamber. Fuel 74 (possibly in slurry
form), oxidizer 75
(such as oxygen or oxygen-enriched air), and high quality water 76 are
injected through fixed
pipes welded or bolted to stationary pressure vessel 71. A high pressure
burner 78 is located
inside the steam generation rotating internal enclosure 72 inside the pressure
vessel. The pressure
in the vessel is in the range of 800kpa-10000kpa, preferably in the range of
2000kpa-4000kpa.
The temperature in the combustion reaction area is in the range of 900-3000 C,
more preferably
in the range of 1300-1600 C at the combustion reaction area. Low quality water
77 is continually
injected and distributed into the internal rotating enclosure through the
distributer flow system 73
where the temperature is reduced on the enclosure walls and the rotating
spherical bodies 713
while steam and solids are formed.
The remaining solids are ground by the free rotating spherical bodies inside
the rotating
enclosure. The rotating enclosure is supported on rotating rollers 710. The
rotating rollers 710
CA 02626416 2008-07-25
can operate hydraulically, electrically or mechanically to maintain the
internal pressure while
transferring the motion energy. The rollers 710 are operated hydraulically
where the hydraulic
flow 711 acts also as a heat removal medium from the mechanical components.
Rotating
cylinder 712 is a typical free rotating roller for supporting the enclosure
weight, as not all the
supporting rollers need to be powered. The sloped pressure vessel is supported
on standard
supports 719. The enclosure is divided by partitions 714 with opposite
orientation openings 715
that direct the flow through the free rotating spherical bodies.
Discharge chamber 721 do not contains spherical bodies. The produced hot gas,
steam
and solid mixture flows to the discharge chamber 721 through opening 720 near
the enclosure
wall to minimize solids build-up. The product is discharged through collector
716 located close
to the bottom of the rotating discharge section 72 and discharged to the
product pipe 717. The
solids can be in a dry grinded form or as a thick slurry forni. Cooling water
continually injected
through pipes 79 is distributed directly on the outside of rotating enclosure
72. The water is
continually collected and discharged at the bottom of the pressure vessel 718.
That cooling water
flow is maintained at a temperature lower than the saturated steam temperature
to maintain liquid
form. As an example, if the reactor pressure is 3000kpa, the circulated water
temperature
discharged will be kept under 230 C.
The cooling water 718 flows to a separating vessel where the solids and
impurities are separated.
The recycled cooling water flows through a heat exchanger where it is cooled
while delivering
heat and recycles back to pipe 79. The produced steam-gas-solids mixture 717
is discharged
from the rotating steam generator at 300 C-650 C and flows through heat
exchanger 751 where
some heat is transferred to a saturated wet flow 753 from vessel 760. The
colder line 752 flows
CA 02626416 2008-07-25
to a solid separation section 754 where most of the solids 757 are separated.
The solid separation
section 754 can be a cyclonic separator, centrifugal separator, mesh separator
or any other
commercially available solids separator. Heat can be recovered from the
rejected solids line 757
through decompression valves and vessel systexn 762 and discharged as a solid
waste 765.
After most of the solids are removed, the lean solids line 755 flows to the
wet solid
scrubber and steam generation vessel 760. The pressure at the vessel is
maintained slightly
higher than EOR injection pressure for the steam and gas mixture, and the
temperature is the
saturated steam temperature. The injected gas 755 generates a constant flex of
heat to vessel 760
that creates steam. Make-up water 759 is injected to the vessel to maintain
the water level. If
required, chemical additives, like limestone slurry 758 can be injected to
react with the sulfur.
Water with high solids content is discharged from the vessel bottom 77 and
recycled back to the
rotating steam generator 73, where the solids will be eventually discharged as
already described
in a dry solid form. The product, which is a high temperature saturated wet
steam-gas mixture
753, flows to heat exchanger 751 where it is heated by flow 717 leaving the
reactor to the range
of 250 C-400 C and becomes a superheated dry steam-COz mixture that can be
delivered
through carbon steel pipelines to EOR injection wells where the mixture is
injected to the
formation without the risk of condensation and corrosion in the flow pipes and
the wells.
The foregoing disclosure and description of the invention is illustrative and
explanatory thereof.
Various changes in the details of the illustrated construction can be made
within the scope of the
appended claims without departing from the true spirit of the invention. The
present invention
should only be limited by the following claims and their legal equivalents.
