U.S. patent application number 14/095803 was filed with the patent office on 2014-06-19 for water with solvent indirect boiling.
This patent application is currently assigned to CONOCOPHILLIPS COMPANY. The applicant listed for this patent is CONOCOPHILLIPS COMPANY. Invention is credited to David W. LARKIN.
Application Number | 20140165929 14/095803 |
Document ID | / |
Family ID | 50929473 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140165929 |
Kind Code |
A1 |
LARKIN; David W. |
June 19, 2014 |
WATER WITH SOLVENT INDIRECT BOILING
Abstract
Systems and methods relate to vaporizing water into steam, which
may be utilized in applications such as bitumen production. The
methods rely on indirect boiling of the water by contact with a
substance such as solid particulate heated to a temperature
sufficient to vaporize the water. Heating of the solid particulate
may utilize pressure isolated heat exchanger units or a hot gas
recirculation circuit at a pressure corresponding to that desired
for the steam. Further, the water may form part of a mixture that
contacts the solid particulate and includes a solvent for the
bitumen in order to limit vaporization energy requirements and
facilitate the production.
Inventors: |
LARKIN; David W.; (Tulsa,
OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
CONOCOPHILLIPS COMPANY |
Houston |
TX |
US |
|
|
Assignee: |
CONOCOPHILLIPS COMPANY
Houston
TX
|
Family ID: |
50929473 |
Appl. No.: |
14/095803 |
Filed: |
December 3, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61737948 |
Dec 17, 2012 |
|
|
|
Current U.S.
Class: |
122/367.1 |
Current CPC
Class: |
F22B 1/028 20130101 |
Class at
Publication: |
122/367.1 |
International
Class: |
F22B 1/02 20060101
F22B001/02 |
Claims
1. A method of vaporizing water, comprising: introducing a solvent
for bitumen into the water to form a mixture; injecting the mixture
into contact with solid particulate heated to a temperature that
results in vaporizing the mixture; and separating water and solvent
vapors from the solid particulate.
2. The method according to claim 1, wherein the solvent includes
hydrocarbons having between 3 and 30 carbon atoms and is introduced
into the water as a liquid.
3. The method according to claim 1, further comprising injecting
the water and solvent vapors into a formation during a steam
assisted gravity drainage operation.
4. The method according to claim 1, wherein the solid particulate
is fluidized during the injecting of the mixture into contact
therewith.
5. The method according to claim 1, further comprising heating the
solid particulate by direct contact with a hot fluid.
6. The method according to claim 1, further comprising heating the
solid particulate by heat exchange with hot fluids separated from
the solid particulate by a thermal conductive material.
7. The method according to claim 1, wherein the water contains at
least 1000 parts per million (ppm) total dissolved solids and at
least 100 ppm organics.
8. The method according to claim 1, wherein organics and dissolved
solids in the water are retained in solid phase with the solid
particulate following the separating.
9. The method according to claim 1, further comprising alternating
between passing the mixture through a vessel containing the solid
particulate in order to vaporize the mixture and passing a hot
fluid through the vessel to reheat the solid particulate.
10. The method according to claim 1, further comprising alternating
between passing the mixture at a first pressure through a vessel
containing the solid particulate in order to vaporize the mixture
and passing oxidant and fuel through the vessel for combustion
therein at a second pressure below the first pressure.
11. The method according to claim 1, wherein the solid particulate
is divided between first and second vessels operating in
corresponding alternation between receiving the mixture for the
vaporizing and receiving hot fluid for reheating the solid
particulate.
12. A method of vaporizing water, comprising: supplying the water
from separated production fluid associated with a steam assisted
gravity drainage bitumen recovery operation; introducing a liquid
hydrocarbon into the water to form a mixture having an energy
requirement for vaporization that is at least 10 percent lower than
water alone; injecting the mixture into contact with a moving
substance heated to result in vaporizing the mixture while at least
some organics and dissolved solids in the water are retained with
the moving substance; and separating water and hydrocarbon vapors
from the moving substance for injection of the vapors in the
bitumen recovery operation.
13. The method according to claim 12, wherein the liquid
hydrocarbon includes butane.
14. The method according to claim 12, wherein the mixture includes
between 5 and 30 percent of the liquid hydrocarbon by volume.
15. The method according to claim 12, wherein the moving substance
includes at least one of sand, metals and cracking catalyst.
16. The method according to claim 12, further comprising burning
off the organics from the moving substance during reheating
thereof.
17. A system for vaporizing water, comprising: a steam generator
coupled to receive liquids including a solvent for bitumen and the
water; solid particulate disposed in the steam generator and in
thermal communication with a heat source for vaporization of the
liquids that contact the solid particulate that is heated; and an
output coupled to the steam generator and through which the water
and solvent vapors exit separated from the solid particulate.
18. The system according to claim 17, wherein the solid particulate
is divided between first and second vessels that operate in
corresponding alternation between receiving the liquids for the
vaporization and hot fluid for reheating the solid particulate.
19. The system according to claim 17, further comprising valves
coupled to the steam generator to alternate between passing the
liquids at a first pressure through the steam generator for the
vaporization and passing oxidant and fuel through the steam
generator for combustion therein at a second pressure below the
first pressure.
20. The system according to claim 17, wherein the solid particulate
includes at least one of sand, metals and cracking catalyst
fluidized in the steam generator.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a non-provisional application which
claims benefit under 35 USC .sctn.119(e) to U.S. Provisional
Application Ser. No. 61/737,948 filed Dec. 17, 2012, entitled
"WATER WITH SOLVENT INDIRECT BOILING," which is incorporated herein
in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] None.
FIELD OF THE INVENTION
[0003] Embodiments of the invention relate to methods and systems
for generating steam which may be utilized in applications such as
bitumen production.
BACKGROUND OF THE INVENTION
[0004] Several techniques utilized to recover hydrocarbons in the
form of bitumen from oil sands rely on generated steam to heat and
lower viscosity of the hydrocarbons when the steam is injected into
the oil sands. One common approach for this type of recovery
includes steam assisted gravity drainage (SAGD). The hydrocarbons
once heated become mobile enough for production along with the
condensed steam, which is then recovered and recycled.
[0005] Costs associated with building a complex, large,
sophisticated facility to process water and generate steam
contributes to economic challenges of oil sands production
operations. Such a facility represents much of the capital costs of
these operations. Chemical and energy usage of the facility also
contribute to operating costs.
[0006] Past approaches rely on once through steam generators
(OTSGs) to produce the steam. However, boiler feed water to these
steam generators requires expensive de-oiling and treatment to
limit boiler fouling problems. Even with this treatment, fouling
issues persist and are primarily dealt with through regular pigging
of the boilers. This recurring maintenance further increases
operating costs and results in a loss of steam production capacity,
which translates to an equivalent reduction in bitumen
extraction.
[0007] Therefore, a need exists for methods and systems for
generating steam that enable efficient hydrocarbon recovery from a
formation.
BRIEF SUMMARY OF THE DISCLOSURE
[0008] In one embodiment, a method of vaporizing water includes
introducing a solvent for bitumen into the water to form a mixture.
The method further includes injecting the mixture into contact with
solid particulate heated to a temperature that results in
vaporizing the mixture. In addition, the method includes separating
water and solvent vapors from the solid particulate.
[0009] According to one embodiment, a method of vaporizing water
includes supplying the water from separated production fluid
associated with a steam assisted gravity drainage bitumen recovery
operation. Introducing a liquid hydrocarbon into the water forms a
mixture having an energy requirement for vaporization that is at
least 10 percent lower than water alone. Injecting the mixture into
contact with a moving substance heated results in vaporizing the
mixture while at least some organics and dissolved solids in the
water are retained with the moving substance. The method also
includes separating water and hydrocarbon vapors from the moving
substance for injection of the vapors in the bitumen recovery
operation.
[0010] For one embodiment, a system for vaporizing water includes a
steam generator coupled to receive liquids including a solvent for
bitumen and the water. The system includes solid particulate
disposed in the steam generator and in thermal communication with a
heat source for vaporization of the liquids that contact the solid
particulate that is heated. Further, the system includes an output
coupled to the steam generator and through which the water and
solvent vapors exit separated from the solid particulate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] A more complete understanding of the present invention and
benefits thereof may be acquired by referring to the following
description taken in conjunction with the accompanying
drawings.
[0012] FIG. 1 is a schematic of a steam generating system that
includes dual vessels arranged to alternate between heating and
steam generation cycles, according to one embodiment of the
invention.
[0013] FIG. 2 is a schematic of a steam generating system with an
exemplary heating vessel through which solid particulate circulates
to regain thermal energy used to vaporize water, according to one
embodiment of the invention.
[0014] FIG. 3 is a schematic of a steam generating system with a
heating vessel in which heat is transferred to solid particulate
via recycled gaseous fluid, according to one embodiment of the
invention.
[0015] FIG. 4 is a schematic of a steam generating system with a
heating vessel in which heat is transferred to solid particulate
via recycled gaseous fluid that is condensed before reheating,
according to one embodiment of the invention.
[0016] FIG. 5 is a schematic of a steam generating system with a
heating vessel having an internal heat exchanger to transfer heat
to solid particulate from hot fluids without direct contact,
according to one embodiment of the invention.
[0017] FIG. 6 is a schematic of a steam generating system with a
single vessel for vaporizing water upon contact with fluidized
solid particulate disposed in the vessel and in thermal contact
with a heat exchanger, according to one embodiment of the
invention.
DETAILED DESCRIPTION
[0018] Turning now to the detailed description of the preferred
arrangement or arrangements of the present invention, it should be
understood that the inventive features and concepts may be
manifested in other arrangements and that the scope of the
invention is not limited to the embodiments described or
illustrated.
[0019] Embodiments of the invention relate to systems and methods
for vaporizing water into steam, which may be utilized in
applications such as bitumen production. The methods rely on
indirect boiling of the water by contact with a substance such as
solid particulate heated to a temperature sufficient to vaporize
the water. Heating of the solid particulate may utilize pressure
isolated heat exchanger units or a hot gas recirculation circuit at
a pressure corresponding to that desired for the steam. Further,
the water may form part of a mixture that contacts the solid
particulate and includes a solvent for the bitumen in order to
limit vaporization energy requirements and facilitate the
production.
[0020] In any embodiments disclosed herein, the water may come from
separated production fluid associated with a steam assisted gravity
drainage (SAGD) bitumen recovery operation. The water at time of
being generated into the steam may still contain: at least about
1000 parts per million (ppm), at least 10,000 ppm or at least
45,000 ppm total dissolved solids; at least 100 ppm, at least 500
ppm, at least 1000 ppm or at least 15,000 ppm organic compounds or
organics; and at least 1000 ppm free oil. Injecting the steam
through an injection well into the formation during the bitumen
recovery operation thus enables sustainable recycle of the water
without stringent treatment requirements of conventional boiler
feed.
[0021] FIG. 1 illustrates a steam generating system that includes a
first vessel 101 and a second vessel 102 that each contains solid
particulate. As used herein, examples of the solid particulate
include sand, metal spheres, cracking catalyst and mixtures
thereof. In some embodiments, fluidization of the solid particulate
keeps the solid particulate moving within the vessels 101, 102
during operation to generate steam. Such fluidization may involve
circulation of the solid particulate and may rely on addition of
supplemental steam.
[0022] Each of the vessels 101, 102 couples to a water injection
line 104 and a heat source line 106. A manifold system controls
flow through the vessels 101, 102 to a steam output 108 and an
exhaust 110 and includes first through eighth valves 111-118. In
operation, the valves 111-118 alternate between heating and steam
generation cycles with the first vessel 101 being shown in the
steam generation cycle while the second vessel 102 is in the
heating cycle.
[0023] As shown, the first and fifth valves 111, 115 on the water
injection line 104 and the steam output 108 thus remain open to
flow of the water through the first vessel 101 to generate the
steam while the third and seventh valves 113, 117 block flow of the
water through the second vessel 102. The steam exits the first
vessel 101 through the steam output 108, which may couple to the
injection well, and is separated from the solid particulate that
remains in the first vessel 101 and may be trapped by filters or
cyclones. The second and sixth valves 112, 116 block flow from the
heat source line 106 to the first vessel 101 at this time while the
fourth and eighth valve 114, 118 are open to flow of oxygen and
fuel, such as methane, from the heat source line 106 through the
second vessel 102 to the exhaust 110. As thermal load of the solid
particulate in the first vessel 101 becomes depleted, position of
each of the valves 111-118 switches such that steam is generated in
the second vessel 102 while the solid particulate is reheated in
the first vessel 101.
[0024] The oxygen and fuel passing through the second vessel 102
combusts to reheat the solid particulate. During such combustion,
contaminants, such as organic compounds deposited on the solid
particulate from the water, may partially or fully convert into
carbon dioxide and water, and some salts deposited on the solid
particulate from the water may come off and be swept out of the
second vessel 102. The combustion heats the solid particulate to a
temperature that results in vaporizing the water upon contact
therewith in the steam generation cycle that follows.
[0025] Not all embodiments rely on such cleaning of the solid
particulate. Surface area of the solid particulate provides enough
dispersion of the deposits to limit heat transfer interference. As
needed over time, replacing some or part of the solid particulate
may ensure desired performance is maintained at minimal cost and
with limited to no interruption. For example, a lockhopper system
employed with embodiments where the solid particulate is always in
a pressurized environment can enable such withdrawal and
replacement while in continuous operation.
[0026] Due to the first and second vessels 101, 102 with the
manifold system, the heat source line 106 can supply the oxygen and
fuel without compression to pressures desired for the steam to be
injected into the formation. This relative lower pressure
combustion facilitates economic production of the steam.
Alternating each of the vessels 101, 102 between the steam
generation cycle and the heating cycle also eliminates need for
conveying the solid particulate to units dedicated to one
particular cycle.
[0027] In some embodiments, the water mixes with a solvent 120 for
the bitumen prior to vaporization due to contact with the solid
particulate. The solvent 120 (common reference number depicted in
all figures) thus may flow as a liquid into the water supply line
104 to form a resulting mixture of the water with the solvent 120.
Vaporization of the water along with the solvent 120 results in the
steam output 108 also containing both water and solvent vapors, as
may be desired for injection into the formation.
[0028] The solvent 120 may include hydrocarbons having between 3
and 30 carbon atoms, such as butane, pentane, naphtha and diesel.
Temperatures associated with the indirect boiling described herein
limit potential problems of cracking the hydrocarbons, which can
tend to occur if passed through direct fired boilers that may thus
require injection of any wanted solvents into steam rather than
boiler feed. Such injection of the solvent into the steam instead
of the water feed may either cause loss of some steam due to
condensation or require superheating of the steam. Conventional
superheating of the steam also suffers from fouling problems.
Therefore, the solvent 120 may flow into steam superheated by steam
generation methods described herein in some embodiments since the
fouling issues from the superheating are overcome in the same
manner as those associated with steam generation.
[0029] The mixture in the water supply line 104 may include between
5 and 30 percent of the liquid hydrocarbon by volume. The mixture
may further provide an energy requirement for vaporization that is
at least 10 percent lower than water alone. For example, a 28:72
ratio of butane to water reduces steam generator duty by 22 percent
as compared to water alone.
[0030] FIG. 2 shows a steam generating system with a steam
generating riser 200 and/or vessel 201 and a heating vessel 202
through which solid particulate are circulated. Similar to the
system in FIG. 1, a heat source line 206 supplies reactants for
combustion within the heating vessel 202 in order regain thermal
energy used to vaporize water. Flue gases from the combustion exit
the heating vessel 202 through exhaust 210 following any filtering
to retain the solid particulate. Multiple alternating heating
vessels with flow control similar to FIG. 1 or lockhoppers may
enable operation of the heating vessel 202 at a lower pressure than
the steam generating riser 200 and/or vessel 201.
[0031] In some embodiments, the solid particulate heated in the
heating vessel 202 transfers to the steam generating vessel 201 by
gravity since the heating vessel 202 is disposed above the steam
generating vessel 201. A water supply line 204 then inputs the
water into contact with the solid particulate that is heated to
result in vaporizing the water and providing a steam output 208.
Some of the steam output 208 may provide lift for the solid
particulate being returned up the riser 200 to the heating vessel
202. For some embodiments, the water vaporizes in the riser 200
such that the steam generating vessel 201 is not even required and
the steam is recovered at a riser output 209.
[0032] FIG. 3 illustrates a steam generating system with a heating
vessel 302 in which heat is transferred to solid particulate via
recycled gaseous fluid circulating in a circuit. Similar to systems
in other figures, the solid particulate once heated transfers to a
steam generating vessel 301 where water 304 is input to contact the
solid particulate and generate steam 308. Embodiments may therefore
implement various features and attributes explained in detail with
respect to another particular figure or elsewhere herein without
being repeated in order to be as succinct as possible.
[0033] The gaseous fluid that exits the heating vessel 302 through
an outlet 310 passes through heat exchanger(s) 350 and a fin-fan
cooler 352, if necessary. The heat exchanger 350 may transfer heat
with the gaseous fluid post compression boosting and/or with the
water 304 being input into the steam generating vessel 301. Such
heat exchange helps maintain efficiency while bringing the
temperature of the gaseous fluid below temperature limits of a
compressor 358 through which the gaseous fluid is sent downstream
in the circuit.
[0034] A purge 354 allows removal of a portion of the gaseous
fluid, which may pick up contaminants, such as from cracking or
entrainment. Makeup gas 356 combines with the gaseous fluid to
replace that purged. In some embodiments, the gaseous fluid
includes an inert gas such as nitrogen and may also include air or
oxygen for burning of the deposits. Methane may provide the gaseous
fluid for some embodiments and may be desired due to its relative
higher thermal capacity.
[0035] The compressor 358 only boosts pressure of the gaseous fluid
circulating through the circuit. For example, the compressor may
provide between 50 and 150 kilopascals (kPa) boost in pressure,
which is achievable without making steam generation uneconomical by
requiring levels of compression needed to increase atmospheric
pressure to above 2500 kPa. The gaseous fluid in the circuit may
thus always remain above 2500 kPa, in some embodiments.
[0036] The gaseous fluid from the compressor 358 then flows through
the circuit to a furnace 360. The furnace 360 burns fuel to reheat
the gaseous fluid that reenters the heating vessel 302 through a
heat source line 306 for sustained heating of the solid particulate
within the heating vessel 302. The heating vessel 302 may include
multiple (e.g., 6 as shown) bed stages 362 or trays such that the
solid particulate passing through the heating vessel 302 counter
current with the gaseous fluid achieves efficient heat cross
exchange.
[0037] Pressure of the steam desired for injection into the
formation dictates pressure inside the steam generating vessel 301.
With the recycled gaseous fluid circulating in the circuit to
reheat the solid particulate, both the steam generating vessel 301
and the heating vessel 302 may operate at this pressure, such as
above 2500 kPa, provided there may be sufficient differences in
pressure in the vessels 301, 302 or other such arrangements
described herein to maintain fluid flows. For some embodiments, a
slipstream 364 of the gaseous fluid also at necessary pressure
provides lift for transporting the solid particulate from the steam
generating vessel 301 to the heating vessel 302.
[0038] FIG. 4 shows a steam generating system with a heating vessel
402 in which heat is transferred to solid particulate via recycled
gaseous fluid that is circulating in a circuit and condensed before
reheating. While shown as being recycled, the gaseous fluid in some
embodiments passes once through the vessel 402 and may then be
utilized in another application. Like the system in FIG. 3, the
solid particulate once heated transfers to a steam generating
vessel 401 where water 404 is input to contact the solid
particulate and generate steam 408. The gaseous fluid that exits
the heating vessel 402 through an outlet 410 passes through heat
exchanger(s) 450 that transfer heat from flow along the circuit
post pumping and/or with the water 404 being input into the steam
generating vessel 401. The heat exchange 450 condenses the gaseous
fluid, such as propane, butane or naphtha, to a liquid phase for
pressurization by a pump 458. Before the pump 458, a separator 454
may enable venting off gasses that are not condensed, such as may
result from cracking of the gaseous fluid.
[0039] Outflow from the pump 458 and any makeup 456 then flows
through the circuit to a furnace 460. The furnace 460 burns fuel to
vaporize and reheat the gaseous fluid that reenters the heating
vessel 402 through a heat source line 406 for sustained heating of
the solid particulate within the heating vessel 402. While pressure
in the circuit again stays at a level similar to that desired for
the steam to be injected into the formation, the pump 458 may
influence efficiency if used in place of compression. Use of the
pump 458 with the gaseous fluid that is condensed may further
enable economic once through heating (i.e., without the circuit) at
the desired pressure similar to approaches depicted in FIG. 1 or 2
(i.e. replace oxygen and methane for combustion with a higher
hydrocarbon pumped and then heated as in FIG. 4) except that
resulting exhaust may have further application for its energy
content.
[0040] FIG. 5 illustrates a steam generating system with a heating
vessel 502 having an internal heat exchanger 562 to transfer heat
to solid particulate from hot fluids without direct contact.
Similar again to systems in other figures, the solid particulate
once heated transfers to a steam generating vessel 501 where water
504 is input to contact the solid particulate and generate steam
508. Both the steam generating vessel 501 and the heating vessel
502 may operate in open pressure communication with one another at
an internal pressure desired for injection of the steam into a
formation while pressure isolated flow through the heat exchanger
562 may be at a lower pressure.
[0041] In operation, oxygen and fuel react in a combustor 560 to
generate a flue gas conveyed to the heat exchanger 562 by a heat
source line 506. The flue gas passes through the heat exchanger 562
and exits via an exhaust 510. A thermally conductive material forms
the heat exchanger 562 such that heat from the flue gas transfers
to the solid particulate in the heating vessel 502. In some
embodiments, the thermally conductive material forms a tube of the
heat exchanger. The tube may coil within the heating vessel 510 to
provide the heat exchanger 562 with either the solid particulate
flowing through an inside of the tube or the flue gas flowing
through the inside of the tube.
[0042] For some embodiments, a fluidization gas, such as air,
passes through the inside of the heating vessel 502. This gas may
help remove contaminants from the solid particulate as well. Use of
the gas for only fluidization while relying on heating by the heat
exchanger 562 limits quantity and compression requirements for the
gas whether the gas is used once through or circulated in a
circuit.
[0043] FIG. 6 shows a steam generating system with a single vessel
600 for vaporizing water upon contact with fluidized solid
particulate disposed in the single vessel 600 and in thermal
contact with a heat exchanger 662. The solid particulate heated by
the heat exchanger 662 contacts water 604 that is input into the
single vessel to generate steam 608. In operation, a circulating
liquid, such as sodium or sodium and potassium, passes through the
heat exchanger 662, exits the heat exchanger via an outlet 610 and
is pumped by an pump 658 to a furnace 660 that reheats the
circulating liquid prior flowing back to the heat exchanger 662 via
inlet 606.
[0044] The heat exchanger 662 transfers heat from the circulating
liquid to the solid particulate and may have a design such as
described with respect to the heat exchanger 562 shown in FIG. 5.
Vaporization of the water 604 still occurs upon contacting the
solid particulate that is heated. While the solid particulate thus
should receive deposits from the water 604, movement of the solid
particulate along the heat exchanger 662 provides abrasion to
ensure that the heat exchanger 662 does not become fouled.
[0045] The heat exchangers 562, 662 in FIGS. 5 and 6 may each
operate with either the flue gas or the circulating liquid as
described herein providing hot fluid thereto. In some embodiments,
systems may incorporate both the heat exchanger 662 where the steam
is being generated along with additional heating of the solid
particulate such as provided in the heating vessel 302 shown in
FIG. 3. Sharing this thermal load may enable efficient
operation.
[0046] Although the systems and processes described herein have
been described in detail, it should be understood that various
changes, substitutions, and alterations can be made without
departing from the spirit and scope of the invention as defined by
the following claims. Those skilled in the art may be able to study
the preferred embodiments and identify other ways to practice the
invention that are not exactly as described herein. It is the
intent of the inventors that variations and equivalents of the
invention are within the scope of the claims, while the
description, abstract and drawings are not to be used to limit the
scope of the invention. Each and every claim below is hereby
incorporated into this detailed description or specification as
additional embodiments of the present invention. The invention is
specifically intended to be as broad as the claims below and their
equivalents.
* * * * *