Note: Descriptions are shown in the official language in which they were submitted.
CA 02739541 2011-05-06
Steam Drive Non-Direct Contact Steam Generation
BACKGROUND OF THE INVENTION
Field of the Invention
[01] This application relates to a system and method for producing steam from
contaminated water feed to recover oil. This invention further relates to
processes and systems for
indirectly using hot fluid heat energy for generating additional steam from
contaminated water, and
using this produced steam for various applications in the oil industry and
possibly in other industries.
The produced steam can be used to generate hot process water in the mining
oilsands industry. It can
also be used for underground injection for Enhanced Oil Recovery. The drive
hot fluid, like steam, is
generated using a commercially available, non-direct heater, steam boiler, co-
gen, OTSG or any other
standard heater or steam generation system. Contaminates, like suspended or
dissolved solids within
the low quality water feed, can be removed in a stable solid (Zero Liquid
Discharge) system.
[02] This application presents a system and method for generating steam at a
controllable pressure
with solids waste removal. The current application is using a non-direct heat
transfer to the contaminate
water (like fine tailings). This is done indirectly, through a metal wall that
is heated with a heating fluid
(preferably steam, however thermal oil or combustion gas can be used as well).
The current application
also describes a system to indirectly generate the steam from the contaminate
water by transferring the
water within the tailings into steam, using the heat and the water with in the
steam to generate hot
water and using the hot water for oilsands extraction. The ability to use the
driving hot fluid, such as
steam, indirectly through a heat exchanger is a significant advantage as the
heating steam can be
recycled back as the heating fluid in a closed system. The heating fluid can
be any type of fluid capable
of transferring thermal heat energy as there is no mixture between the thermal
driving fluid and the
tailings. The focus of the current invention is on the use of FT (Fine
Tailings) or MFT (Mature Fine
Tailings) from an open mine oilsands extraction facility to generate hot
process water and solid waste.
However, it can be applicable to other applications as well, for example the
use of water treatment
sludge waste from water softening facilities or other wet streams with large
solid contamination
content. The driving steam is generated by a commercially available non-direct
steam generation
facility. The driving steam is indirectly used to transfer liquid water into
steam and solid waste. The
current invention also suggests a system and apparatus to generate the steam
and solids from the
contaminate tailings. The system includes a longitude heated enclosure with a
mechanical means to
transfer the generated solids and slurry within the enclosure and to prevent
solids build-up and fouling
within the enclosure. The system can further include a collector to collect
and separate the produced
steam and solids, possibly from plurality of longitude steam generated
enclosures connected to a
common separator.
[03] The steam can be generated by a standard, commercially available
industrial (package)
boiler or can be provided directly from a power station. The most suitable
steam will be a medium
pressure steam, as would be typically used for heating purposes. A cost
efficient, hence effective
system, would be to employ a high pressure steam turbine to generate
electricity. The discharge steam
from the turbine, at a lower pressure, can be effective as a driving heating
steam. Due to the fact that
CA 02739541 2011-05-06
the first stage turbine, which is the smallest size turbine, produces most of
the power (due to a higher
pressure), the cost per Megawatt of the steam turbine will be relatively low.
The efficiency of the system
will not be affected as the discharged steam will be used to drive the water
out from the fine tailings, or
other sludge, through a heat exchanger with means to mobilize the solids, as
described in this
application.
[04] During the generation of steam from the highly contaminated liquid feed,
like tailings, the
mechanical property of the liquid feed changes with the heat transfer and the
conversion of the water
into vapor, increasing the solid content (like the clay and sand when FT or
MFT is used) to produce solid
waste that can be easily disposed of and can support traffic. The vapor water
and heat is used to
generate the extraction hot water. At this process, the MFT properties are
changing from a liquid phase
to a thick paste phase and eventually to stable solids. This phase change, the
changing heat transfer
coefficient through the metal wall combined with the presence of clay and
abrasive sand and oil
contaminates make the final stage of the non-direct contact heat transfer very
challenging. This
invention will also suggest a system to introduce a mechanical energy to the
heat transfer volume while
allowing an effective heat transfer area and an effective system arrangement,
including an effective
arrangement for combining such units into a single maintainable system. The
system includes the
collection of the steam generators discharge and the solids separation from
the steam.
[05] The driving steam is generated in a Non-Direct Steam Generator (like a
steam boiler with a
steam drum and a mud drum), or "Once-Through Steam Generator" (OTSG) COGEN
that uses the heat
from a gas turbine to generate steam, or any other available design. The heat
transfer and combustion
gases are not mixed and the heat transfer is done through a wall (typically a
metal wall), where the
pressure of the generated steam is higher than the pressure of the combustion.
This allows for the use
of atmospheric combustion pressure. The product is pure steam (or a steam and
water mixture, as in
the case of the OTSG) without combustion gases.
[06] There are several applicable patents and disclosures issued in the field
of the present
invention. US patent No. 7,591,309 issued to Minnich et al. on September 22,
2009 describes the use of
steam for operating a pressurized evaporation facility where the pressurized
vapor steam is injected into
an underground formation for EOR. The steam heats the brine water which is
boiled to generate
additional steam. To prevent the generation of solids in the pressurized
evaporator, the internal
surfaces are kept wet by liquid water and the water is pre-treated to prevent
solid build up. The
concentrated brine is discharged for disposal or for further treatment in a
separate crystallizing facility
to achieve a ZLD system.
[071 Canadian patent application 2,677,479 by Spiers et al describes a drying
process for
tailings. The tailings are dried in a dryer where the tailings water is
converted to steam. The generated
steam is condensed and its heat is used to pre-heat the tailings. Make-up
Steam is also used to dry the
tailings. The water extracted from the tailings is used in the extraction
facility.
[08] This invention's method and system for indirectly generating steam from
fine tailings for
extraction of heavy bitumen includes the steps as described in the patent
figures and their descriptions.
[09] The advantage and the objective of the present invention are described in
the patent
application and in the attached figures and their descriptions.
[10] These and other objectives and advantages of the present invention will
become apparent
from a reading of the attached specifications and appended claims.
CA 02739541 2011-05-06
SUMMARY OF THE INVENTION
[11] The method and system of the present invention is for steam production
for extraction of heavy
bitumen by using fine tailings in a non-direct steam generation process. The
produced water vapor is
furthered used as part of an above ground oil extraction facility or for an
underground formation. The
method includes the following steps: (1) Generating hot fluid stream, like a
steam stream; (2) Using the
heat to indirectly evaporate liquid water with significant levels of solids,
oil contamination and other
contaminates (like tailings) without mixing the steam gas with the liquid
water; (3) Indirectly
converting liquid phase water into gas phase steam and solids contaminates;
(4) Removing the solid
contaminates that were supplied with the water for disposal or further
treatment; (6) Using the
generated steam for directly or indirectly heating process water for an above
ground oilsands mine or
for injecting the produced steam into an underground oil formation through
SAGD or CSS steam
injection well.
[12] In another embodiment, the invention can include a non-direct contact
steam generation
system from fine tailings comprising: (1) a longitude enclosure with heated
wall; (2) The heated wall is
heated with the use of steam with steam supply line and condensate recovery
line. (3) The enclosure
length is at least twice longer then its diameter; (4) The enclosure includes
mechanical moving internals,
preferably longitude rotating internals, capable of mobilizing solids from
heat transfer areas and
mobilizing solids through the enclosure to the discharge.
[13] In another embodiment, the enclosure is connected to a separation unit,
capable of separating
the generated steam from the solids, where the separation unit includes any
commercially available
separation unit, like cyclone, centrifugal, mesh, electrostatic and
combinations of different units.
[14] In another embodiment, several enclosures are connected to a common
collector unit that
separates the solids and slurry from the gas phase. Several efficient
horizontal and vertical
arrangements are disclosed.
[15] The system and method's different aspects of the present invention are
clear from the following
figures.
DETAILED DESCRIPTION OF THE DRAWINGS
[16] FIGURES 1, 1A, 1B and 1C show the conceptual flowchart of the method and
the system of the
presented invention.
[17] FIGURE 2 shows a schematic comparison between the prior art 2A to the
present invention 2B.
Drawing 2A describes the present method of the prior art for generating the
hot process water used for
oilsands extraction. Steam 2 is used in commercially available heat exchanger
1 to heat the process
water 4. Many types of shell and tube or any other commercially available heat
exchangers can be used.
The steam condensate 3, after its heat was recovered to heat the process
water, is recycled and used
again in the boilers for generating additional steam. The process water 4 is
heated through heat
exchanger 1 to generate the hot extraction process water 5, typically at
temperature in the range of
70-90 C. The hot extraction water is mixed with the oilsands to generate
slurry and separate the oil from
the sand. Drawing 2B describes the proposed method for indirectly generating
the hot process water for
oilsands extraction. Similar to the prior art, steam 11 is used to provide the
heat energy to drive the
CA 02739541 2011-05-06
process. The steam condensate 12 is recycled back to the boiler in a close
system. Fine tailings stream 13
is heated indirectly by the steam 11 to the stage it is transferred to a solid
material and gas phase that
contains mainly steam, as well as other hydrocarbons and non-condensed gas
components 15. The
solids 17 are removed from the gas phase 18 at separator 16. The water vapor
18 is condensed while
heating process water 14 to generate hot extraction water 20. The hot
extraction water 20 is further
mixed with the mined oilsands. The solids from the fine tailings or the mature
fine tailings is tracked
back to the mine and used as back-fill where it can support traffic.
[18] FIGURE 3 describes the proposed method for indirectly generating the hot
process water for
oilsands extraction. Steam 12 is used to provide the heat energy to drive the
process. The steam
condensate 5 is recycled back to the boiler in a closed system (not shown).
Fine tailing stream 7 is
heated indirectly by the steam and the condensate in two stages. In the first
stage 6, defined as pre-
heating, the MFT is heated without a phase change. The heated tailings 9 are
still in a liquid phase.
Steam is supplied to non-direct contact steam generator 10, where the heat
energy of the condensing
steam 12 is used to evaporate the tailings to generate steam (water vapor) and
solid waste. Mechanical
energy is introduced to the tailings during the process 10. One example of a
system to perform the
process in unit 10 is described in Figure 4. The solid discharge 15 is
separated from the gas flow 13 and
tracked back to a landfill location. The solid lean gas flowl6 mainly contains
steam from the tailings
water that were evaporated and which are used for heating the process water 4
to generate hot
extraction process water 3 by direct or non-direct heat exchange 17. Any
contamination NCG (non
condensing gas) 18, like light hydrocarbons resulting from hydrocarbons and
solvent within the tailing
feed 7, are separated. They can be further combusted as a fuel source in a
boiler (not shown). The hot
process water is mixed with oilsands ore to generate slurry and separate the
oil from the sand and clay.
[19] Figure 4 shows a non-direct tailings steam generation system. Fine
tailings 6, like MFT, is fed
into a non-direct contact steam generator 1 that includes a heat exchanger in
the form of a longitudinal
externally heated pipe 2. The external wall of the pipe 2 is continually
heated, preferably with steam 7,
to generate heat flow to the internal volume of the pipe that is sufficient to
evaporate the water within
the tailings 6. The driving steam 7 condensate 8 is recycled, possibly after
recovering its heat through
heat exchanger to pre-heat the tailings or for other purposes, back to the
boiler to generate additional
driving steam 7 (not shown). The driving steam 7 can be replaced with other
methods of heating pipe 2,
such as thermal oil. Pipe 2 includes internal rotating element 9 to provide
mechanical energy into the
tailings, especially into the dried tailings close to the discharge end. The
mechanical mixing energy is
designed to mobilize the solids within pipe enclosure 2, increase the heat
exchange efficiency with the
slurry, and clean the surface of the tube to increase the heat transfer
efficiency. The rotating element 9
can include screws, scoops or any commercially available rotating internals.
Two rotating screws 13 and
14 can be used as well, where, due to the rotating movement, the screws will
clean each other while
mixing and mobilizing the slurry and solids. To enhance the heat exchange to
the tailings, the heat
exchange is extended in the longitudinal direction where the length L is at
least twice the diameter D.
[20] Figure 4A shows a non-direct, tailings steam generating system. Fine
tailings 6, like MFT, is fed
into a non-direct contact steam generator 1 that includes a heat exchanger in
the form of a longitudinal
externally heated pipe 2. System 1 is described in Figure 4. The discharge
from the steam generator 1 is
fed into a separator 10. The solids are collected at the bottom of the
separator and discharged through
discharge hopper 13 to reduce the discharge pressure through double valve 12
and 14. The system can
CA 02739541 2011-05-06
include additional separation units to separate fine solid particles. This can
include one or more internal
cyclones 11 to separate carry-on solid particles from the gas flow. External
separation units, like external
cyclones 17, can be used as well. The produced solids lean stream 20 is used
as a water and heat source
to generate the hot extraction process water.
[21] Figure 5 shows the vertical arrangement of non-direct contact longitude
steam generators and a
center collector / separator for the produced gas and solids. The longitude
steam generator is described
in Figure 4. Driving steam 12 is used to evaporate the fine tailings 13 and
convert it into steam and
solids. The solids are removed with the help of mechanical rotating energy 15
to transfer the solids to
the center collector 16. Several longitude steam generators are arranged on
top of each other where
their discharge is collected by a collector 16. The collector has a gas
(steam) discharge outlet 17 at its
upper section and solids discharge 20 at its lower section. The lower section
can include a cone to
reduce the solids discharge diameter. The collecting container 16 can include
an apparatus to remove
solids deposits (not shown). Such an apparatus can move through the longitude
axis and use mechanical
energy or pressurized fluid to clean vessel 16 walls.
[22] Figure 5A shows the horizontal arrangement of non-direct contact
longitude steam
generators and a center collector / separator for the produced gas and solids.
The longitude steam
generator is described in Figure 4. Driving steam 12 is used to evaporate the
fine tailings 13 and convert
it into steam and solids. The solids inside the steam generator 2 are
mobilized with the help of
mechanical rotating energy 15 to transfer the solids to the center collector
16 and remove any fouling
from the heat transfer wall of the steam generator. Several longitude steam
generators 1 and 2 and
possibly 3, 4 and 5 can be arranged with their discharge connected to
centralized collector 16. The
longitude steam generators 1 and 2 can be arranged from both sides of the
collector 16. Additional
steam generators can be added also from additional directions of the
centralized collector 16, like 3, 4
and 5. The collector has a gas (steam) discharge outlet 17 at its upper
section and solids discharge outlet
20 at its lower section. The collecting container 16 can include an apparatus
22 to remove solids
deposits from the collecting enclosure 16. This apparatus 23 is capable of
moving inside enclosure 16,
close to its wall and scraping deposits, possibly with a rotating movement and
with the help of a
pressurized fluid. Another option is to add an internally rotating element
inside enclosure 16 that will
mobilize solids and slurry to the bottom discharge (not shown). The solids 20
are discharged through
outlet 19.
[23] Figure 5B shows an arrangement of non-direct contact longitude steam
generators inside a
common heating steam enclosure with a common collector / separator for the
produced gas and solids.
The structure of each longitude steam generator 34 is described in Figure 4,
with the notable difference
that the steam generator of Figure 5B does not includes the double wall as the
heating steam is
enclosed in enclosure 30. Driving steam 31 is used to evaporate the fine
tailings 32 and convert it into
steam and solids. The driving steam condensate is discharged from outlet 29 at
the bottom of the
heating steam enclosure 35. The solids are removed with the help of mechanical
rotating energy 37 to
transfer the solids to the center collector 16. Several longitude steam
generators are arranged with their
discharge connected to the discharge collector side 42. The discharge
collector has a gas (steam)
discharge outlet 41 at its upper section and solids discharge outlet 40 at its
lower section. The discharge
collector 42 can include an apparatus to remove solids deposits (not shown). A
single heating steam
enclosure 35 heats multiple longitude steam generators 34. The driving steam
31 and the produced
CA 02739541 2011-05-06
steam generated from the tailings 32 are separated and can be at a different
pressure due to the
separation between the heating enclosure 35 and the discharge cover 42.
Typically the pressure of the
driving steam in enclosure 35 is higher than the pressure on the discharge
side 42.
[24] Figure 6 is a schematic view of the invention, with an open mine oilsands
extraction facility,
where the hot process water for the ore preparation is generated from
condensing the steam produced
from the fine tailings. A typical mine and extraction facility is briefly
described in block diagram 1 (See
"Past, Present and Future Tailings, Tailing Experience at Albian Sands Energy"
presentation by
Jonathan Matthews from Shell Canada Energy on December 8, 2008 at the
International Oil Sands
Tailings Conference in Edmonton, Alberta). Mined oil sand feed is transferred
in trucks to an ore
preparation facility, where it is crushed in a semi-mobile crusher 3. It is
also mixed with hot water 52 in a
rotary breaker 5. Oversized particles are rejected and removed to a landfill.
The ore mix goes through
slurry conditioning, where it is pumped through a special pipeline 7.
Chemicals and air are added to the
ore slurry 8. Air is injected at 8 to generate an aerated slurry flow. The
conditioned aerated slurry flow is
fed into the bitumen extraction facility, where it is injected into a Primary
Separation Cell 9. To improve
separation, the slurry is recycled through floatation cells 10. Oversized
particles are removed through a
screen 12, in the bottom of the separation cell. From the flotation cells, the
coarse and fine tailings are
separated in separator 13. The fine tailings flow to thickener 18. To improve
the separation in the
thickener, flocculant is added 17. Recycled water 16 is recovered from the
thickener and fine tailings are
removed from the bottom of thickener 18. The froth is removed from the Primary
Separation Cell 9, to
vessel 21. In this vessel, steam 14 is injected to remove air and gas from the
froth. The recovered froth is
maintained in a Froth Storage Tank 23. The steam can be produced in a standard
high pressure steam
boiler 40, in OTSG or by a COGEN, using the temperature in a gas turbine tail
(not shown). The tailing
water from the oilsand mine facility 1 is disposed of in a tailing pond,
described in BLOCK 6. The tailing
pond is built in such a way that the sand tailings are used to build the
containment areas for the fine
tailings. The tailing sources come from Extraction Process. They include
coarse tailings and the fine
tailings from the thickener 18, where flocculants are added to enhance the
solid settling and recycling of
warm water. Another source of fine tailings are the Froth Treatment Tailings,
where the tailings are
discarded by the solvent recovery process, characterized by high fines
content, relatively high
asphaltene content and residual solvent. (See "Past, Present and Future
Tailings, Tailing Experience at
Albian Sands Energy" a presentation by Jonathan Matthews from Shell Canada
Energy on December 8,
2008 at the International Oil Sands Tailings Conference in Edmonton, Alberta).
A Sand dyke 55 contains
the tailings pond. The sand separates from the tailing and generates a sand
beach 56. Fine tailings 57 are
put above the sand beach at the middle-low section of the tailing pond. Some
fine tailings are trapped in
the sand beach 56. On top of the fine tailings is the recycled water layer 58.
The tailing concentration
increases with depth. Close to the bottom of the tailing layer are the MFT
(Mature Fine Tailings). (See
"The Chemistry of Oil Sands Tailings: Production to Treatment" presentation by
R.J. Mikula, V.A. Munoz,
O.E. Omotoso, and K.L. Kasperski of CanmetENERGY, Devon, Alberta, Natural
Resources Canada on
December 8, 2008 at the International Oil Sands Tailings Conference in
Edmonton, Alberta). The
recycled water 41 is pumped from a location close to the surface of the
tailing pond, (typically from a
floating barge). The fine tailings are pumped from the deep areas of the fine
tailings pond 43. MFT
(Mature Fine Tailing) 43 is pumped from the lower section of the tailing pond
and is then directed to the
non-direct contact steam generator (NDCSG) 31. Prior to injection into the non-
direct contact steam
generator, the fine tailings can be heated in heat exchanger 39. The heat can
be supplied from hot
tailing streams, like 15, that are sent to the tailing pond. In this case, the
tailing stream will be fed as
stream 51 into the MFT pre-heating heat exchanger 39 (not shown). Another
option is to use the
condensate 35 from the NDCSG 31 for pre-heating the MFT. For that option the
condensate 35 will be
CA 02739541 2011-05-06
fed as stream 51 into the pre-heating heat exchanger 39. Heat exchanger 39 can
be any available design
that can heat thick material like MFT. There are many commercially available
heat exchangers; some
include self-cleaning designs that can be used at 39. The fine tailings 33 are
feed into the NDCSG 31
where they are heated to a stage where the water evaporates into steam, slurry
and solids. The slurry
and solids are mobilized with the help of mechanical energy, like a longitude
rotating screw 34.
However, any available NDCSG that can transfer the MFT to gas and solids can
be used as well. Under
the heat and pressure inside the NDCSG, the MFT turns into gas and solids, as
the water is converted to
steam. The solids are recovered at the bottom of the collector / separator 37
in a dry form or in a
semi-dry, semi-solid slurry form 51. The semi- dry slurry form is stable
enough to be sent back into the
oilsands mine without the need for further drying, to support traffic. The
water vapor that was
generated from heating the fine tailing in the NDCSG is used to heat the
extraction facility process water
62. During this process they are also condensed and can be added to the
extraction process as well. In
unit 60 the water vapors are condensed while the process water 62is heated,
generating hot process
water 52 used for the extraction process. Non condensable gas 61 can be
recovered after the water
vapor condenses. The NCG 61 can occur as a result of hydrocarbons in the
tailing feed 43. It can be
combusted as an energy source. Another option is to inject the NCG 61 for
froth aeration in 8 to replace,
at least partly, the used air (not shown). Unit 60 can be arranged directly or
indirectly as described in
units 70 and 77. In a non-direct heat exchanger / condenser the produced steam
71, (which is also flow
38) is condensed on the heat exchanger where the cold process water is heated.
The condensate 72 and
the hot process water do not mix. The condensed steam 72 can be added to the
heated process water
73 at a later stage (not shown).The heated process water 73 is flow 52 and is
used in the extraction plant
of BLOCK 5. NCG 75 is removed from the system where they can be burned or
injected to the froth for
enhancing the separation of the bitumen from the water. Unit 77 describes a
direct contact heat
exchanger that can be used as unit 60 for recovering the heat and water from
the produced steam while
generating hot process water. The produced steam 38 is injected at 78, where
it is mixed with the cold
process water 79 to generate hot process water 76 which includes the condensed
steam that is
converted into liquid water. The hot process water includes the water from the
produced steam. The
heated process water 76 is flow 52 and is used in the extraction plant of
BLOCK 5. Any generated NCG 80
is removed and used for combustion, froth separation or for other various
uses. The temperature of the
discharged hot water 57 is between 70C-95C, typically in the 80C-90C range.
The hot water is supplied
to the ore preparation facility. The separated dry solids 36 can be mixed with
additional MFT, possibly
after thickening. Any commercially available mixing method can be used in the
process: a rotating mixer,
Z type mixer, screw mixer, extruder or any other commercially available mixer
(not shown). By
continually consuming the fine tailing water 43, the oil sand mine facility
can use a much smaller tailing
pond as a means of separating the recycled water from the fine tailing. This
solution will allow for the
creation of a sustainable, fully recyclable water solution for the open mine
oilsands facilities.
