U.S. patent application number 12/914781 was filed with the patent office on 2011-11-03 for bitumen extraction and asphaltene removal from heavy crude using high shear.
This patent application is currently assigned to H R D CORPORATION. Invention is credited to Rayford G. Anthony, Gregory G. Borsinger, Abbas Hassan, Aziz Hassan, Krishnan Viswanathan.
Application Number | 20110266198 12/914781 |
Document ID | / |
Family ID | 44060261 |
Filed Date | 2011-11-03 |
United States Patent
Application |
20110266198 |
Kind Code |
A1 |
Hassan; Abbas ; et
al. |
November 3, 2011 |
BITUMEN EXTRACTION AND ASPHALTENE REMOVAL FROM HEAVY CRUDE USING
HIGH SHEAR
Abstract
Herein disclosed is a method of removing at least one component
from a feed by subjecting the feed to high shear in the presence of
carbon dioxide to produce a high shear-treated product and
separating the at least one component from the high shear-treated
product to produce a component-reduced product. Also disclosed is a
method of removing asphaltenes from asphaltenic oil by subjecting
the asphaltenic oil to a shear rate of at least 10,000 s.sup.-1 in
the presence of carbon dioxide to produce a high shear-treated
product and separating asphaltenes from the high shear-treated
product to produce an asphaltene-reduced product oil. Systems are
also provided for carrying out the methods.
Inventors: |
Hassan; Abbas; (Sugar Land,
TX) ; Hassan; Aziz; (Sugar Land, TX) ;
Viswanathan; Krishnan; (Houston, TX) ; Borsinger;
Gregory G.; (Chatham, NJ) ; Anthony; Rayford G.;
(College Station, TX) |
Assignee: |
H R D CORPORATION
Houston
TX
|
Family ID: |
44060261 |
Appl. No.: |
12/914781 |
Filed: |
October 28, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61262027 |
Nov 17, 2009 |
|
|
|
Current U.S.
Class: |
208/390 ;
196/46 |
Current CPC
Class: |
B03D 1/08 20130101; C10G
2300/206 20130101; C10G 21/003 20130101; C10G 1/04 20130101; Y02P
20/582 20151101; C10G 2300/107 20130101; C10G 31/00 20130101; B03D
1/1406 20130101; C10G 2300/308 20130101; B03D 1/247 20130101; C10G
2300/1033 20130101; B03D 1/02 20130101; B03D 1/1468 20130101; B03D
2203/006 20130101; B03D 1/082 20130101; C10G 2300/1077
20130101 |
Class at
Publication: |
208/390 ;
196/46 |
International
Class: |
C10G 1/04 20060101
C10G001/04; C10G 1/00 20060101 C10G001/00 |
Claims
1. A method of removing at least one component from a feed
comprising tailings, asphaltenic oil or a combination thereof, the
method comprising: subjecting the feed to high shear in the
presence of carbon dioxide to produce a high shear-treated product;
and separating the at least one component from the high
shear-treated product to produce a component-reduced product.
2. The method of claim 1 wherein subjecting the feed to high shear
in the presence of carbon dioxide further comprises subjecting the
feed to a shear rate of at least 10,000 s.sup.-1.
3. The method of claim 2 wherein subjecting the feed to high shear
in the presence of carbon dioxide comprises a shear rate of at
least 20,000 s.sup.-1.
4. The method of claim 1 wherein subjecting the feed to high shear
comprises introducing the feed and carbon dioxide into a high shear
device comprising at least one rotor and at least one
complementarily-shaped stator.
5. The method of claim 4 wherein high shear comprises a shear rate
of at least 10,000 s.sup.-1, wherein the shear rate is defined as
the tip speed divided by the shear gap, and wherein the tip speed
is defined as .pi.Dn, where D is the diameter of the at least one
rotor and n is the frequency of revolution.
6. The method of claim 5 wherein high shear comprises a shear rate
of at least 20,000 s.sup.-1.
7. The method of claim 5 wherein subjecting the feed to a shear
rate of at least 10,000 s.sup.-1 produces a local pressure of at
least about 1034.2 MPa (150,000 psi) at a tip of the at least one
rotor.
8. The method of claim 4 wherein subjecting the feed to high shear
comprises providing a tip speed of the at least one rotor of at
least about 23 m/sec, wherein the tip speed is defined as .pi.Dn,
where D is the diameter of the at least one rotor and n is the
frequency of revolution.
9. The method of claim 1 wherein the high shear-treated product
comprises a dispersion of carbon dioxide bubbles.
10. The method of claim 9 wherein the carbon dioxide bubbles have
an average bubble diameter of less than about 1 micron.
11. The method of claim 10 wherein the carbon dioxide bubbles have
an average bubble diameter of less than about 0.5 micron.
12. The method of claim 1 wherein the feed comprises tailings from
a caustic bitumen extraction process and the component-reduced
product comprises water having less than 10 wt % impurities.
13. The method of claim 12 further comprising recycling at least a
portion of the water to the bitumen extraction process.
14. The method of claim 12 wherein separating the at least one
component comprises separating solids from the high shear-treated
product to produce a solids-reduced product and separating an oil
phase from the solids-reduced product to produce the
component-reduced product, wherein the component-reduced product
comprises water.
15. The method of claim 12 wherein the tailings are obtained from a
tailings pond of a bitumen extraction process.
16. The method of claim 12 wherein at least a portion of the
tailings are produced by: mixing tar sand and water in a tumbler or
a hydrotransport line to form a froth; introducing the froth into a
separation cell; and removing the at least a portion of the
tailings from the separation cell.
17. The method of claim 12 wherein at least a portion of the
tailings are produced by introducing a middlings portion from a
separation cell of a bitumen extraction process into a secondary
separation unit and extracting the at least a portion of the
tailings from the secondary separation cell.
18. The method of claim 12 wherein at least a portion of the
tailings are produced by introducing a bitumen froth from a
separation cell of a bitumen extraction process into one or more
centrifuge and extracting the at least a portion of the tailings
from the one or more centrifuge.
19. The method of claim 12 wherein subjecting the feed comprising
tailings to high shear in the presence of carbon dioxide reduces
the pH to less than about 6.
20. The method of claim 19 wherein subjecting the feed to high
shear converts the caustic in the tailings to sodium bicarbonate,
enhancing the rate of separation of water from the tailings
relative to conventional tailings treatment processes.
21. The method of claim 1 wherein the feed comprises asphaltenic
oil, the at least one product comprises asphaltenes and the
component-reduced product comprises asphaltene-reduced oil.
22. The method of claim 21 wherein the asphaltenic oil is selected
from the group consisting of bitumen comprising at least some
percentage of asphaltenes, heavy crude oil comprising at least some
percentage of asphaltenes, and combinations thereof.
23. The method of claim 21 wherein separating the at least one
component from the high shear-treated product to produce a
component-reduced product comprises introducing the high
shear-treated product into a centrifuge operated to separate
asphaltenes from asphaltene-reduced product oil.
24. The method of claim 21 wherein the asphaltenic oil feed is
subjected to high shear in the presence of water.
25. The method of claim 21 wherein the feed has an API gravity of
less than about 10 and the asphaltene-reduced product oil has an
API gravity of greater than about 10.
26. The method of claim 21 wherein the asphaltene-reduced product
oil comprises at least about 90 wt % bitumen.
27. The method of claim 21 wherein the asphaltene-reduced product
oil comprises less than about 10 wt % asphaltenes.
28. The method of claim 21 wherein the asphaltene-reduced product
oil comprises less than about 5 wt % water, less than about 1 wt %
solids, or both.
29. A method of removing asphaltenes from asphaltenic oil, the
method comprising: subjecting the asphaltenic oil to a shear rate
of at least 10,000 s.sup.-1 in the presence of carbon dioxide to
produce a high shear-treated product; and separating asphaltenes
from the high shear-treated product to produce an
asphaltene-reduced product oil.
30. The method of claim 29 wherein the asphaltenic oil is selected
from bitumen and heavy crude oils.
31. The method of claim 29 further comprising separating carbon
dioxide from the high shear-treated product and recycling the
separated carbon dioxide to the subjecting step.
32. The method of claim 29 wherein the asphaltene-reduced oil
product comprises less than about 10 wt % asphaltenes.
33. In an aqueous bitumen extraction process comprising forming a
bitumen froth by tumbling tar sand with water and base in a tumbler
or hydrotransporting tar sand with water and base in a transport
pipeline; and separating the bitumen froth from tailings in a
separation cell; the improvement comprising: subjecting the
tailings to high shear in the presence of carbon dioxide to produce
a high shear-treated product; separating solids from the high shear
treated product to produce a solids-reduce product; separating
water from the solids-reduced product; and recycling the water to
the froth forming step.
34. The method of claim 33 wherein the water comprises less than
about 10, 5, 3, or 1 wt % impurities.
35. The method of claim 33 wherein separating solids from the high
shear treated product to produce a solids-reduce product is
performed with at least one centrifuge.
36. The method of claim 33 wherein separating water from the
solids-reduced product is performed with at least one settling
tank.
37. The method of claim 36 wherein an oil phase is removed from an
upper portion of the settling tank and the water from a lower
portion of the settling tank.
38. The method of claim 33 wherein subjecting the tailings to high
shear in the presence of carbon dioxide produces a high
shear-treated product having a pH of less than about 6.
39. A system for removing at least one component from a feed
comprising tailings, asphaltenic oil or a combination thereof, the
system comprising: at least one high shear device comprising at
least one rotor and at least one complementarily-shaped stator and
configured to subject the feed to high shear in the presence of
carbon dioxide and produce a high shear-treated product, wherein
the at least one high shear device is configured to subject the
contents therein to a shear rate of at least 10,000 s.sup.-1,
wherein the shear rate is defined as the tip speed divided by the
shear gap, and wherein the tip speed is defined as .pi.Dn, where D
is the diameter of the at least one rotor and n is the frequency of
revolution; and at least one separation unit configured to separate
a component from the high shear-treated product, providing a
component-reduced product.
40. The system of claim 39 wherein the at least one rotor is
configured to provide a tip speed of at least about 23 m/sec.
41. The system of claim 39 wherein the at least one rotor is
configured to provide a tip speed of at least about 40 m/sec.
42. The system of claim 39 wherein the at least one rotor is
separated from the at least one stator by a shear gap of less than
about 5 .mu.m, wherein the shear gap is the minimum distance
between the at least one rotor and the at least one stator.
43. The system of claim 39 wherein the feed comprises tailings from
a bitumen extraction process, wherein the at least one component
comprises solids and oil and wherein the system comprises a first
separation unit configured to separate solids from the high
shear-treated product producing a solids-reduced product and a
second separation unit configured to separate oil from the
solids-reduced product providing substantially pure water as
component-reduced product.
44. The system of claim 43 further comprising a tailings pond from
which the feed is obtained.
45. The system of claim 43 wherein the first separation unit is a
centrifuge and the second separation unit is a settling tank.
46. The system of claim 39 wherein the feed comprises asphaltenic
oil, wherein the at least one component comprises asphaltenes, and
wherein the component-reduced product comprises asphaltene-reduced
oil.
47. The system of claim 46 wherein the feed has an API gravity of
less than 10 and wherein the asphaltene-reduced product has an API
gravity of greater than 10.
48. The system of claim 46 wherein the asphaltene-reduced oil
comprises less than about 10 wt % asphaltenes.
49. The system of claim 48 wherein the asphaltene-reduced oil
further comprises less than about 5 wt % solids, less than 5 wt %
water or both.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit under 35 U.S.C.
.sctn.119(e) of U.S. Provisional Patent Application No. 61/262,027,
filed Nov. 17, 2009, the disclosure of which is hereby incorporated
herein by reference.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
[0002] Not Applicable.
BACKGROUND
[0003] 1. Technical Field
[0004] The present invention relates to systems and methods for
enhanced recovery and processing of heavy crude and/or bitumen.
More particularly, the present invention relates to the high shear
removal of asphaltenes from feeds comprising bitumen and/or heavy
crude oil and the high shear separation of water and mineral solids
from tailings conventionally sent to a tailings pond.
[0005] 2. Background of the Invention
[0006] Large deposits of heavy hydrocarbon sometimes referred to as
bitumen are located in many countries around the world. Bitumen may
be recoverable by means of secondary or tertiary recovery processes
that involve heating, solubilization or mobility control. Many of
these heavy hydrocarbon deposits contain high concentrations of
asphaltenes that contribute to difficulties in recovery,
transporting and upgrading. Oil sands, also, known as tar sands,
are heavy hydrocarbons found in the United States, Canada, Russia,
Venezuela, and various countries in the Middle East. Deposits in
the oil sands of Alberta Canada are the single-largest known source
of petroleum in the world. These oil sands contain bitumen and as
much as 17 wt % asphaltenes. The Orinoco oil belt in Venezuela is
another large accumulation of bitumen. Additionally, heavy crudes
produced all over the world typically contain some amount of
asphaltenes.
[0007] Heavy crude oil or crude bitumen extracted from the earth is
in a viscous, solid or semi-solid form that does not flow easily at
normal oil pipeline temperatures, making it difficult to transport
and expensive to process into gasoline, diesel fuel, and other
products. The economic recovery and utilization of heavy
hydrocarbons, including bitumen, is a significant energy challenge.
The demand for heavy crudes, such as those extracted from oil
sands, has increased significantly due to dwindling reserves of
conventional lighter crude. These heavy hydrocarbons, however, are
typically located in geographical regions far removed from existing
refineries. Consequently, the heavy hydrocarbons are often
transported via pipelines to refineries. In order to transport
heavy crudes in pipelines they must meet pipeline quality
specifications.
[0008] Extraction techniques utilized to recover bitumen may be
broken down into three major categories: (1) those which employ
water, either hot or cold, to float the bitumen oils away from the
tar-sands, (2) those which employ an organic solvent to dissolve
the bitumen oils, and (3) those that involve heat. Extraction of
bitumen may be either by removing the deposits from the ground and
extracting the bitumen externally or by in situ extraction, where
only the bitumen is removed and the mineral components are left in
the ground. Processes utilizing water often involve air floatation,
and typically involve the utilization of an alkaline material. Due
to the formation of stable emulsions containing fine tar-sands ore
particles, water and bitumen oils, water-based processes are not
particularly efficient, especially on ore of lower bitumen content.
The treatment of emulsions comprising large volumes of water,
bitumen oils and fine tar-sands ore particles has proven
challenging.
[0009] Extraction of bitumen using heat can be done with electric,
steam or other form of heaters as described, for example, in U.S.
Pat. App. Nos. 2008/0135253 and 2009/0095480 by Vinegar et al.
Various combinations of extraction techniques can be used to
extract bitumen in situ. It is generally believed that in situ
extraction will be more cost effective than surface mining,
although the predominant method of bitumen extraction used today is
surface mining. Another solvent extraction technique under
development involves the utilization of solvents (in the absence of
water) and is similar to techniques utilized in oil seed extraction
processes. Percolation and immersion-type extractors have been
used, but the need for special designs and scale-up for processing
of abrasive tar-sands make economical extraction difficult. For
example, the solvent to bitumen ratio needed for efficient
extraction is generally high, up to 10:1, producing concomitantly
high capital and utilities costs for recovery of the solvent via,
for example, distillation. For economy of solvent utilization,
spent sands must be stripped of residual solvent prior to disposal.
Stripping of residual solvent is a capital and energy intensive
undertaking.
[0010] Existing solvent extraction methods for dissolving bitumen
oils from tar-sands, for example, as disclosed in U.S. Pat. No.
4,160,718 issued to Rendall, typically involve environmentally
unacceptable losses of solvent and additional problems associated
with the hazards posed by the necessary storage of large solvent
inventories and the need for large quantities of water. Other
solvent, hot water, and combination extraction processes are
disclosed in U.S. Pat. No. 4,347,118 to Funk et al. and U.S. Pat.
No. 3,925,189 to Wicks, III. These methods all have commercial
and/or ecological drawbacks, rendering them undesirable. A method
that utilizes both solvent and hot water for extraction of bitumen
from tar-sands is the subject of U.S. Pat. No. 4,424,112 to
Rendall.
[0011] Bitumen extraction techniques that do not involve solvent
conventionally utilize truck and shovel operations. In such
operations, the oil sand is first mined and then is delivered to a
crusher. In one such process, bitumen separation and recovery from
the oil sand is accomplished by following what is known as the
Clark hot water extraction process. In the front end of this
process, crushed oil sand is mixed with hot water and caustic in a
rotating tumbler or conditioned in a pipeline to produce aqueous
slurry. In the tumbler or pipeline, bitumen globules contact and
coat air bubbles that are entrained in the slurry. The slurry is
then screened to remove large rocks and the like. The screened
slurry is diluted with additional water and the product is then
temporarily retained in a primary separation vessel (PSV). In the
PSV, the buoyant bitumen-coated air bubbles rise through the slurry
and form bitumen froth. The sand in the slurry settles and is
discharged from the base of the PSV, together with some water and
bitumen. This stream or portion is referred to as the `PSV
underflow` or tailings. A `middlings` portion comprising water,
non-buoyant bitumen and fines may be collected from the middle of
the PSV. The froth overflows the lip of the PSV and is recovered as
the primary froth and typically comprises .about.60 wt. % bitumen,
.about.30 wt. % water and .about.10 wt. % particulate solids.
[0012] The PSV underflow is introduced into a deep cone vessel,
referred to as the tailings oil recovery vessel (`TORV`). Here the
PSV underflow is contacted and mixed with a stream of aerated
middlings from the PSV. Again, bitumen and air bubbles contact and
unite to form buoyant globules that rise and form froth. This
`secondary` froth overflows the lip of the TORV and is recovered.
The secondary froth typically comprises .about.45 wt. % bitumen,
.about.45 wt. % water and .about.10 wt. % solids. The middlings
from the TORV is withdrawn and processed in a series of
sub-aerated, impeller-agitated flotation cells. Secondary froth,
typically comprising .about.40 wt. % bitumen, .about.50 wt. % water
and .about.10 wt. % solids, is produced from these cells.
[0013] The primary and secondary froth streams are typically
combined to yield a product froth stream, often comprising
.about.60 wt. % bitumen, .about.32 wt. % water and .about.8 wt. %
solids. The water and solids in the froth are contaminants which
need to be reduced in concentration before the froth can be treated
in a downstream refinery-type upgrading facility. This cleaning
operation is generally carried out using what is referred to as
`froth treatment.`
[0014] While there are a variety of froth treatment processes, all
of these processes include deaeration of the combined froth product
followed by dilution with sufficient solvent, typically naphtha, to
provide a solvent to froth ('S/F') ratio of about 0.40 (w/w). This
is done to increase the density differential between the diluted
bitumen on the one hand and the water and solids on the other. By
way of example, Kizior (U.S. Pat. No. 4,383,914), Guymon (U.S. Pat.
No. 4,968,412), Shelfantook et al. (Canadian Pat. No. 1,293,465),
Birkholz et al. (Canadian Pat. No. 2,232,929), Tipman et al.
(Canadian Pat. No. 2,200,899), Tipman et al. (Canadian Pat. No.
2,353,109), Mishra et al. (U.S. Pat. No. 6,019,888), Cymerman et
al. (U.S. Pat. No. 6,746,599), Beetge et al. (U.S. Pat. App.
20060196812, and Graham et al. (U.S. Pat. No. 5,143,598) describe
ways of processing and treating the froth produced during the
extraction process.
[0015] A serious problem, however, in using a solvent extraction
process to remove bitumen from such a carbonaceous solid is that
fines, primarily particles less than 50 microns in diameter, are
carried over in the solvent-dissolved bitumen extract. Failure to
remove the fines results in an undesirable high-ash bitumen product
as well as problems with plugging of equipment used in the
separation process, especially, for example, filtration equipment.
Similar problems arise when other carbonaceous liquids besides
bitumen, such as coal liquid or shale oil, are used. Removal of the
fines during recovery of the bitumen from a carbonaceous solid or
from a previously recovered carbonaceous liquid is therefore
important in providing a desirable low-ash liquid product and
minimizing fouling and plugging of equipment used in the process.
It would be highly desirable to develop an extraction method for
recovering bitumen from the aforesaid carbonaceous solids and for
removing fines from the aforesaid carbonaceous liquids which would
permit control of the solvency power of the extraction solvent so
as to maximize the amount of bitumen or other carbonaceous liquid
recovered and to minimize the fines content therein.
[0016] Following extraction of bitumen, a diluent such as light
naphtha is often added for transportation. The naphtha must be
distilled and recycled, adding to energy costs. Changes in
temperature and/or composition may cause the asphaltenes to fall
out of solution, necessitating pipeline cleaning. Typically,
removal of asphaltenes desirably removes some of the heavy metals
and sulfur associated with crude oil. It is well known that
asphaltenes can be separated from bitumen or asphaltenic crude oil
by precipitation with paraffinic solvents such as pentane or
heptanes (see, for example, U.S. Pat. App. 2006/0260980 to Yeung;
U.S. Pat. App. 2008/0245705 to Siskin et al.; U.S. Pat. No.
5,326,456 to Brons et al.; U.S. Pat. No. 5,316,659 et al.; U.S.
Pat. No. 4,699,709 to Peck et al.; and U.S. Pat. No. 4,596,651 to
Wolff et al.). Additionally, various settling aids and/or
flocculants have been utilized to enhance separation of asphaltenes
(see, for example, U.S. Pat. App. 2006/0196812 to Beetge et
al.).
[0017] It is conventionally believed that a high solvent to oil
ratio (e.g., on the order of 40:1 by volume) is required to
separate substantially-pure asphaltenes from bitumen or asphaltic
crude oil. At lower solvent levels, commonly used in solvent
deasphalting, substantial non-asphaltenic material precipitates
with the asphaltenes, resulting in undesirable oil losses.
Furthermore, solvent deasphalting relies on multiple theoretical
stages of separation of barely immiscible hydrocarbon liquids, such
stages are intolerant to the presence of water. The oil yield of
solvent deasphalting is also limited by the high viscosity of the
resultant asphaltic materials, particularly for high viscosity
bitumen feeds. It is thus difficult to obtain high quality oil with
high oil yield due to the difficulties in achieving clean
separation of the oil and asphaltic fractions. In solvent
deasphalting, asphalt (essentially asphaltenes with residual oil)
is produced as a very viscous hot liquid, which forms glassy solids
when cooled. This viscous liquid must be heated to a high
temperature in order to be transportable, causing fouling and
plugging limitations.
[0018] Another technique for removal of asphaltenes involves
breaking a froth of extra heavy oil and water with heat and a
diluent solvent such as naphtha. In the case of paraffinic naphtha,
partial asphaltene removal results. However, only about 50% of the
asphaltenes may be readily removed with this treatment even with
multiple stages and complete removal of asphaltenes is thus not
practical. As a result, the resulting oils must still be processed
by capital intensive technology that is relatively tolerant to
asphaltenes.
[0019] Despite the development of the above mentioned froth and
solvent extraction processes, there remains a need for improved
systems and processes of extracting bitumen of higher quality, for
example, containing less water, less solids, less asphaltenes
and/or less diluent. It would be desirable if the enhanced systems
and processes would allow increased bitumen recovery, for example,
by reducing oil losses during asphaltene removal and/or reduced oil
losses in the tailings. There is also a need in the art for a
method of selectively and efficiently removing asphaltenic
contaminants from heavy oil, which mitigates the above-mentioned
difficulties of the prior art. It would be even further desirable
if the systems and processes would allow bitumen extraction and/or
asphaltene removal without requiring high solvent and/or
water-to-bitumen ratios, long residence times or numerous or
expensive processing units. Such systems and processes should
desirably facilitate recycle and thus economy of utilization of
process water and/or conditioning agents, such as base (e.g.,
caustic) and/or bicarbonate.
SUMMARY
[0020] Herein disclosed is a method of removing at least one
component from a feed comprising tailings, asphaltenic oil or a
combination thereof, the method comprising: subjecting the feed to
high shear in the presence of carbon dioxide to produce a high
shear-treated product; and separating the at least one component
from the high shear-treated product to produce a component-reduced
product. Subjecting the feed to high shear in the presence of
carbon dioxide may further comprise subjecting the feed to a shear
rate of at least 10,000 s.sup.-1. In embodiments, subjecting the
feed to high shear in the presence of carbon dioxide comprises a
shear rate of at least 20,000 s.sup.-1. In embodiments, subjecting
the feed to high shear comprises introducing the feed and carbon
dioxide into a high shear device comprising at least one rotor and
at least one complementarily-shaped stator. High shear may comprise
a shear rate of at least 10,000 s.sup.-1, wherein the shear rate is
defined as the tip speed divided by the shear gap, and wherein the
tip speed is defined as .pi.Dn, where D is the diameter of the at
least one rotor and n is the frequency of revolution. In
embodiments, high shear comprises a shear rate of at least 20,000
s.sup.-1. In embodiments, subjecting the feed to a shear rate of at
least 10,000 s.sup.-1 produces a local pressure of at least about
1034.2 MPa (150,000 psi) at a tip of the at least one rotor. In
embodiments, subjecting the feed to high shear comprises providing
a tip speed of the at least one rotor of at least about 23 m/sec,
wherein the tip speed is defined as .pi.Dn, where D is the diameter
of the at least one rotor and n is the frequency of revolution.
[0021] In embodiments, the high shear-treated product comprises a
dispersion of carbon dioxide bubbles. The carbon dioxide bubbles
may have an average bubble diameter of less than about 1 micron. In
embodiments, the carbon dioxide bubbles have an average bubble
diameter of less than about 0.5 micron.
[0022] In embodiments, the feed comprises tailings from a caustic
bitumen extraction process and the component-reduced product
comprises water having less than 10 wt % impurities. The method may
further comprise recycling at least a portion of the water to the
bitumen extraction process. Separating the at least one component
may comprise separating solids from the high shear-treated product
to produce a solids-reduced product and separating an oil phase
from the solids-reduced product to produce the component-reduced
product, wherein the component-reduced product comprises water. In
embodiments, the tailings are obtained from a tailings pond of a
bitumen extraction process. In embodiments, at least a portion of
the tailings are produced by: mixing tar sand and water in a
tumbler or a hydrotransport line to form a froth; introducing the
froth into a separation cell; and removing the at least a portion
of the tailings from the separation cell. In embodiments, at least
a portion of the tailings are produced by introducing a middlings
portion from a separation cell of a bitumen extraction process into
a secondary separation unit and extracting the at least a portion
of the tailings from the secondary separation cell.
[0023] In embodiments, at least a portion of the tailings are
produced by introducing a bitumen froth from a separation cell of a
bitumen extraction process into one or more centrifuge and
extracting the at least a portion of the tailings from the one or
more centrifuge. In embodiments, subjecting the feed comprising
tailings to high shear in the presence of carbon dioxide reduces
the pH to less than about 6. In embodiments, subjecting the feed to
high shear converts the caustic in the tailings to sodium
bicarbonate, enhancing the rate of separation of water from the
tailings relative to conventional tailings treatment processes.
[0024] In embodiments, the feed comprises asphaltenic oil, the at
least one product comprises asphaltenes and the component-reduced
product comprises asphaltene-reduced oil. The asphaltenic oil may
be selected from the group consisting of bitumen comprising at
least some percentage of asphaltenes, heavy crude oil comprising at
least some percentage of asphaltenes, and combinations thereof.
Separating the at least one component from the high shear-treated
product to produce a component-reduced product may comprise
introducing the high shear-treated product into a centrifuge
operated to separate asphaltenes from asphaltene-reduced product
oil.
[0025] In embodiments, the asphaltenic oil feed is subjected to
high shear in the presence of water. In embodiments, the feed has
an API gravity of less than about 10 and the asphaltene-reduced
product oil has an API gravity of greater than about 10. In
embodiments, the asphaltene-reduced product oil comprises at least
about 90 wt % bitumen. In embodiments, the asphaltene-reduced
product oil comprises less than about 10 wt % asphaltenes. In
embodiments, the asphaltene-reduced product oil comprises less than
about 5 wt % water, less than about 1 wt % solids, or both.
[0026] Also disclosed herein is a method of removing asphaltenes
from asphaltenic oil, the method comprising: subjecting the
asphaltenic oil to a shear rate of at least 10,000 s.sup.-1 in the
presence of carbon dioxide to produce a high shear-treated product;
and separating asphaltenes from the high shear-treated product to
produce an asphaltene-reduced product oil. In embodiments, the
asphaltenic oil is selected from bitumen and heavy crude oils. The
method may further comprise separating carbon dioxide from the high
shear-treated product and recycling the separated carbon dioxide to
the subjecting step. In embodiments, the asphaltene-reduced oil
product comprises less than about 10 wt % asphaltenes.
[0027] Also disclosed, is an improvement in an aqueous bitumen
extraction process comprising forming a bitumen froth by tumbling
tar sand with water and base in a tumbler or hydrotransporting tar
sand with water and base in a transport pipeline; and separating
the bitumen froth from tailings in a separation cell; the
improvement comprising: subjecting the tailings to high shear in
the presence of carbon dioxide to produce a high shear-treated
product; separating solids from the high shear treated product to
produce a solids-reduce product; separating water from the
solids-reduced product; and recycling the water to the froth
forming step. The water may comprise less than about 10, 5, 3, or 1
wt % impurities. Separating solids from the high shear treated
product to produce a solids-reduce product may be performed with at
least one centrifuge. Separating water from the solids-reduced
product may be performed with at least one settling tank. In
embodiments, an oil phase is removed from an upper portion of the
settling tank and the water from a lower portion of the settling
tank. In embodiments, subjecting the tailings to high shear in the
presence of carbon dioxide produces a high shear-treated product
having a pH of less than about 6.
[0028] Also disclosed is a system for removing at least one
component from a feed comprising tailings, asphaltenic oil or a
combination thereof, the system comprising: at least one high shear
device comprising at least one rotor and at least one
complementarily-shaped stator and configured to subject the feed to
high shear in the presence of carbon dioxide and produce a high
shear-treated product, wherein the at least one high shear device
is configured to subject the contents therein to a shear rate of at
least 10,000 s.sup.-1, wherein the shear rate is defined as the tip
speed divided by the shear gap, and wherein the tip speed is
defined as .pi.Dn, where D is the diameter of the at least one
rotor and n is the frequency of revolution; and at least one
separation unit configured to separate a component from the high
shear-treated product, providing a component-reduced product. In
embodiments, the at least one rotor is configured to provide a tip
speed of at least about 23 m/sec. In embodiments, the at least one
rotor is configured to provide a tip speed of at least about 40
m/sec. In embodiments, the at least one rotor is separated from the
at least one stator by a shear gap of less than about 5 .mu.m,
wherein the shear gap is the minimum distance between the at least
one rotor and the at least one stator.
[0029] In embodiments, the feed comprises tailings from a bitumen
extraction process, the at least one component comprises solids and
oil and the system comprises a first separation unit configured to
separate solids from the high shear-treated product producing a
solids-reduced product and a second separation unit configured to
separate oil from the solids-reduced product providing
substantially pure water as component-reduced product. The system
may further comprise a tailings pond from which the feed is
obtained. In embodiments, the first separation unit is a centrifuge
and the second separation unit is a settling tank. In embodiments,
the feed comprises asphaltenic oil, the at least one component
comprises asphaltenes, and the component-reduced product comprises
asphaltene-reduced oil. The feed may have an API gravity of less
than 10 and the asphaltene-reduced product may have an API gravity
of greater than 10. In embodiments, the asphaltene-reduced oil
comprises less than about 10 wt % asphaltenes. In embodiments, the
asphaltene-reduced oil further comprises less than about 5 wt %
solids, less than 5 wt % water or both.
[0030] According to embodiments of this disclosure, a high shear
device is used to improve the recovery and processing of heavy
crude bitumen. In one aspect of the present invention a high shear
device is used in combination with reactive gas (e.g. carbon
dioxide) to enhance the separation of clay and other inorganic
mineral solids from the bitumen once it is extracted from the
ground. In another aspect of the present invention a high shear
device is used in combination with carbon dioxide to enhance the
separation of asphaltenes and other undesirable elements of bitumen
following removal of inorganic contaminants, thus allowing for
easier transportation and downstream processing of the recovered
bitumen.
[0031] Certain embodiments of the above-described methods or
systems potentially provide overall cost reduction by reducing the
size and/or number of downstream purification apparatus/steps,
providing oil having reduced levels of impurities including, but
not limited to, asphaltenes, sand, silt, solids, sulfur and/or
other heavy metals, and/or water, permitting operation at low
temperature and/or pressure relative to conventional heavy crude
oil or bitumen processing, and/or reducing capital and/or operating
costs of bitumen extraction or heavy crude oil processing. These
and other embodiments and potential advantages will be apparent in
the following detailed description and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] For a more detailed description of the preferred embodiment
of the present invention, reference will now be made to the
accompanying drawings, wherein:
[0033] FIG. 1 is a schematic of a high shear system comprising an
external high shear mixer/disperser according to an embodiment of
the present disclosure.
[0034] FIG. 2 is a schematic of a high shear system comprising an
external high shear mixer/disperser according to another embodiment
of the present disclosure.
[0035] FIG. 3 is a schematic flow diagram of a prior art hot water
extraction process suitable for incorporation, as indicated, for
example, by arrows A and B, of one or more high shear devices
according to this disclosure.
[0036] FIG. 4 is a longitudinal cross-section view of a high shear
mixing device suitable for use in embodiments of the disclosed
system.
[0037] FIG. 5 is a box flow diagram of a method of removing a
component from a stream produced in heavy oil or bitumen recovery
and/or processing.
NOTATION OF NOMENCLATURE
[0038] As used herein, the phrase `asphaltenic oil` refers to any
oil containing at least some percentage of asphaltenes. The
`asphaltenic oil` may be, for example, bitumen comprising
asphaltenes, heavy crude oil comprising asphaltenes, and the
like.
[0039] As used herein, the term `dispersion` refers to a liquefied
mixture that contains at least two distinguishable substances (or
`phases`). As used herein, a `dispersion` comprises a `continuous`
phase (or `matrix`), which holds therein discontinuous droplets,
bubbles, and/or particles of the other phase or substance. The term
dispersion may thus refer to foams comprising gas bubbles suspended
in a liquid continuous phase, emulsions in which droplets of a
first liquid are dispersed throughout a continuous phase comprising
a second liquid with which the first liquid is immiscible, and
continuous liquid phases throughout which solid particles are
distributed. As used herein, the term "dispersion" encompasses
continuous liquid phases throughout which gas bubbles are
distributed, continuous liquid phases throughout which solid
particles are distributed, continuous phases of a first liquid
throughout which droplets of a second liquid that is substantially
insoluble in the continuous phase are distributed, and liquid
phases throughout which any one or a combination of solid
particles, immiscible liquid droplets, and gas bubbles is
distributed. Hence, a dispersion can exist as a homogeneous mixture
in some cases (e.g., liquid/liquid phase), or as a heterogeneous
mixture (e.g., gas/liquid, solid/liquid, or gas/solid/liquid),
depending on the nature of the materials selected for combination.
A dispersion may comprise, for example, bubbles of gas (e.g. carbon
dioxide) in a liquid (e.g. stream comprising tailings, bitumen
and/or heavy crude oil) and/or droplets of one fluid in a phase
with which it is immiscible.
[0040] Use of the phrase, `all or a portion of is used herein to
mean `all or a percentage of the whole` or `all or some components
of.`
DETAILED DESCRIPTION
[0041] Overview. Herein disclosed are systems and methods of
removing a component from a stream produced during recovery and/or
processing of heavy crude oil or bitumen (e.g. from tar sands). The
system and method are utilized, in embodiments, to precipitate
asphaltenes from bitumen or heavy crude oil. In embodiments, the
system and method are suitable for facilitating recovery of water
from slurries (comprising sediments/sand particles) that are
conventionally introduced into tailings ponds or recycled back to
the process. The system comprises an external high shear mechanical
device to provide rapid contact and mixing of reactants in a
controlled environment in the reactor/mixer device. In embodiments,
the system and method allow removal of asphaltenes at lower
temperatures and/or pressures than conventional methods or more
rapid and complete removal of asphaltenes. In embodiments, the
system and method allow extraction of bitumen from tar sands with
utilization of less water by facilitating removal of water from a
stream produced during extraction and recycle of removed water for
further extraction. A reactor assembly that comprises an external
high shear device (HSD) or mixer as described herein may decrease
mass transfer limitations and thereby allow faster precipitation
and/or removal of a desired component, such as precipitation and
removal of asphaltenes from oil, removal of solids from tailings,
and removal of water from tailings.
[0042] System for Removal of a Component from a Stream Produced
during Recovery and/or Processing of Heavy Crude Oil or Bitumen.
Herein disclosed is a system for removal of a component from a
stream produced during recovery and/or processing of heavy crude
oil or bitumen. In embodiments, the system is utilized for removal
of asphaltenes from asphaltenic heavy crude oil or bitumen. In
embodiments, the system is utilized to enhance extraction of
bitumen from tar sand and reduce water usage during extraction.
[0043] FIG. 1 is a schematic of a high shear system 100 according
to an embodiment of this disclosure. System 100 comprises high
shear device 140 and centrifuge 160. Although described herein as a
centrifuge, it is to be understood that unit 160 may be any gravity
metric separation device known to those experienced in the art can
also be used. FIG. 2 is a schematic of a high shear system 300
according to another embodiment of this disclosure. High shear
system 300 comprises a source 305 of material conventionally
introduced into a tailings pond and a settling tank 390 in addition
to high shear device 340 and centrifuge 360. Optionally the
bitumen/water mix may be introduced directly to the high shear
device from a tumbler extraction unit where the bitumen is
initially separated from the sand. Each of these components of high
shear systems 100/300 is described in more detail hereinbelow. One
or more lines are connected to the HSD for introducing feed mixture
thereto. As pure bitumen is rather thick and not readily pump-able
diluents might be added at any stage. Additionally, in order to
avoid having to dilute the bitumen, following separation of the
sand, the extracted water/bitumen mix (dilute bitumen) can be
subjected to CO.sub.2 and shear and the asphaltene dropped out, in
embodiments. The CO.sub.2 bitumen/water mix may be heated as
necessary following the shear.
[0044] In the embodiment of FIG. 1, lines 110, 120 and 130 are
fluidly connected with HSD 140 for the introduction of feed
comprising bitumen, heavy crude or streams conventionally sent to a
tailings pond; reactant gas (e.g. carbon dioxide); and (optionally)
water, respectively. In alternative embodiments, a single inlet
line is fluidly connected with the HSD and the feed (e.g.,
tailings, bitumen, water and/or heavy crude oil), reactant gas
(e.g. carbon dioxide), and optionally additional water are combined
prior to introduction into the HSD. For example, in the embodiment
of FIG. 2, tailings from source 305 (e.g. a tailings pond) is
combined in line 310 with reactant gas (e.g. carbon dioxide) in
line 320 prior to introduction into HSD 340. Water, either heated
or at ambient conditions can be added at any point in the process
to aid in flow to aid in the formation of carbonic acid and/or to
aid in the separation of unwanted elements from the product oil
(e.g. bitumen).
[0045] In addition to carbon dioxide, various other compounds can
be reacted with the asphaltenes to cause them to separate out
including SO.sub.3, NO.sub.2, and P.sub.2O.sub.5 as described in US
Patent App. No. 2008/0251418. In the case of reaction with
SO.sub.3, the asphaltene can be dimerized. Although description is
made primarily with respect to utilization of carbon dioxide as
reactant, it is to be understood that other reactions that
destabilize asphaltenes can also be accelerated via the
herein-disclosed utilization of high shear. For example, air or
O.sub.2 may also be introduced to aid in separation and/or to aid
in BOD/COD (biological oxygen demand, chemical oxygen demand)
reductions of the water.
[0046] Water, either heated or at ambient conditions can be added
at any point in the process to aid in flow, formation of carbonic
acid and aid in the separation of unwanted elements from the
bitumen.
[0047] Flow line 150/350 carries a high shear-treated stream out of
HSD 140. How line 150/350 is any line into which the high
shear-treated stream from HSD 140/340 (comprising a dispersion of
reactant gas in feed) flows. One or more dispersible gas lines
120/320 are configured to introduce gas into HSD 140/340. The
reactant gas may be selected from carbon-dioxide-containing gas
streams, or may be substantially pure carbon dioxide, in certain
applications. In embodiments, the reactant is any reactant known to
result in aromatic substitution, for example, as per U.S. Patent
App. No. 2008/0251418, which is hereby incorporated herein for all
purposes not contrary to this disclosure. Line(s) 120/320 may
introduce reactant gas into HSD 140/340 directly or may introduce
reactant gas into the HSD via line 110/310.
[0048] Centrifuge 160/360 is fluidly connected to HSD 140/340 via
high shear-treated product flow line 150/350. Centrifuge 160/360
may comprise one or more outlet lines. For example, in the
embodiment of FIG. 1, centrifuge 160 comprises heavy component
outlet line 170 and component-reduced (e.g., asphaltene-reduced)
product outlet line 180. A gas outlet line 175 may be fluidly
connected with the centrifuge for removal of reactant or product
gas. A recycle line may fluidly connect the gas outlet line with
reactant gas inlet line 120/320, for recycle of reactant gas to HSD
140/340. In the embodiment of FIG. 2, centrifuge 360 comprises a
heavy component outlet line 370 and a component-reduced (e.g.,
solids-reduced) product outlet line 380.
[0049] As mentioned hereinabove, the high shear system may further
comprise a feed source. For example, bitumen or heavy crude for
introduction into HSD 140 via line 110 may be produced using
apparatus known in the art and discussed further hereinbelow with
respect to FIG. 4. Feed introduced into HSD 340 via feed line 310
may comprise tailings conventionally introduced into a tailings
pond or recycled. The tailings may be produced using any means
known in the art, and high shear system 340 may comprise apparatus
for the production of such tailings. In instances, system 300 may
further comprise feed source 305 which may comprise, for example, a
tailings pond. In other embodiments, the tailings are produced
utilizing any combination of the apparatus disclosed in U.S. Pat.
No. 5,626,743. In embodiments, the disclosed system obviates the
need for a conventional tailings pond, and the use of the term
tailings is meant to indicate those streams conventionally
introduced into a tailings pond but does not require that the
tailings come from a tailings pond, per se.
[0050] The high shear system may also comprise downstream
processing apparatus. For example, high shear system 340 may
further comprise separation apparatus 390 adapted for separation of
a water phase from an oil phase. Separation apparatus 390 may
comprise a settling tank. Component-reduced product outlet line 380
fluidly connects centrifuge 360 with separation apparatus 390.
Separation apparatus 390 is configured to provide adequate
residence time for separation of an oil phase comprising oil (e.g.
bitumen) from an aqueous phase. The aqueous phase may comprise
bicarbonate.
[0051] A recycle line may fluidly connect separation apparatus 390
with a system for water extraction of bitumen from tar sands, such
that the recovered water from separation apparatus 390 may be
recycled for further extraction. Suitable systems for extraction of
bitumen from tar sands include hot water extraction systems, for
example, as disclosed in U.S. Pat. No. 5,626,743. FIG. 3 is a prior
art system for hot water extraction of bitumen from tar sands, as
described in U.S. Pat. No. 5,626,743. High shear system 100/300 may
be incorporated into an existing system for extraction of bitumen
from tar sands or may be incorporated into a system for the
processing of heavy crude oil. In embodiments, high shear system
100/300 further comprises a combination of the apparatus indicated
in FIG. 4, whereby the feed to HSD 140/340 is obtained. Thus, in
embodiments, high shear system 100/300 further comprises one or
more tumblers 18, one or more transport pipes adapted for
hydrotransport of feed whereby a bitumen froth is formed, one or
more separation cells 24, one or more tailings ponds 52, one or
more secondary separation units 28, or some combination
thereof.
[0052] Additional components or process steps can be incorporated
between HSD 140/340 and centrifuge 160/360 or ahead of HSD 140/340,
if desired, as will become apparent upon reading the description of
the high shear process hereinbelow.
[0053] High Shear Device 140. The high shear system comprises at
least one high shear device 140/340. External high shear device
(HSD) 140/340, also sometimes referred to as a high shear mixer, is
configured for receiving a feed stream, via line 110/310. As
mentioned above, HSD 140/340 may comprise one or more additional
inlet lines 120, 130 for introduction of reactant gas or water,
respectively. One or more line(s) 120 may be configured to
introduce reactant gas into HSD 140. The HSD may be configured for
receiving feed mixture and reactant gas via separate inlet lines
110 and 120, respectively, or the feed and reactant gas may be
combined prior to introduction into the HSD. Although only one HSD
is shown for contacting reactant gas and feed mixture in the
embodiments of FIGS. 1 and 2, it should be understood that some
embodiments of the system can comprise two or more HSDs for
contacting feed and reactant gas. The two or more HSDs can be
arranged in either series or parallel flow. In embodiments, high
shear system 100/300 comprises a single HSD.
[0054] HSD 140/340 is a mechanical device that utilizes one or more
generators comprising a rotor/stator combination, each of which has
a gap between the stator and rotor. The gap between the rotor and
the stator in each generator set may be fixed or may be adjustable.
HSD 140/340 is configured in such a way that it is capable of
effectively contacting the components therein at rotational
velocity. The HSD comprises an enclosure or housing so that the
pressure and temperature of the fluid therein may be
controlled.
[0055] High shear mixing devices are generally divided into three
general classes, based upon their ability to mix fluids. Mixing is
the process of reducing the size of particles or inhomogeneous
species within the fluid. One metric for the degree or thoroughness
of mixing is the energy density per unit volume that the mixing
device generates to disrupt the fluid particles. The classes are
distinguished based on delivered energy densities. Three classes of
industrial mixers having sufficient energy density to consistently
produce mixtures or emulsions with particle sizes in the range of
submicron to 50 microns include homogenization valve systems,
colloid mills and high speed mixers. In the first class of high
energy devices, referred to as homogenization valve systems, fluid
to be processed is pumped under very high pressure through a
narrow-gap valve into a lower pressure environment. The pressure
gradients across the valve and the resulting turbulence and
cavitation act to break-up any particles in the fluid. These valve
systems are most commonly used in milk homogenization and can yield
average particle sizes in the submicron to about 1 micron
range.
[0056] At the opposite end of the energy density spectrum is the
third class of devices referred to as low energy devices. These
systems usually have paddles or fluid rotors that turn at high
speed in a reservoir of fluid to be processed, which in many of the
more common applications is a food product. These low energy
systems are customarily used when average particle sizes of greater
than 20 microns are acceptable in the processed fluid.
[0057] Between the low energy devices and homogenization valve
systems, in terms of the mixing energy density delivered to the
fluid, are colloid mills and other high speed rotor-stator devices,
which are classified as intermediate energy devices. A typical
colloid mill configuration includes a conical or disk rotor that is
separated from a complementary, liquid-cooled stator by a
closely-controlled rotor-stator gap, which is commonly between
0.025 mm to 10 mm (0.001-0.40 inch). Rotors are usually driven by
an electric motor through a direct drive or belt mechanism. As the
rotor rotates at high rates, it pumps fluid between the outer
surface of the rotor and the inner surface of the stator, and shear
forces generated in the gap process the fluid. Many colloid mills
with proper adjustment achieve average particle sizes of 0.1 to 25
microns in the processed fluid. These capabilities render colloid
mills appropriate for a variety of applications including colloid
and oil/water-based emulsion processing such as that required for
cosmetics, mayonnaise, or silicone/silver amalgam formation, to
roofing-tar mixing.
[0058] The HSD comprises at least one revolving element that
creates the mechanical force applied to the reactants therein. The
HSD comprises at least one stator and at least one rotor separated
by a clearance. For example, the rotors can be conical or disk
shaped and can be separated from a complementarily-shaped stator.
In embodiments, both the rotor and stator comprise a plurality of
circumferentially-spaced rings having complementarily-shaped tips.
A ring may comprise a solitary surface or tip encircling the rotor
or the stator. In embodiments, both the rotor and stator comprise
more than 2 circumferentially-spaced rings, more than 3 rings, or
more than 4 rings. For example, in embodiments, each of three
generators comprises a rotor and stator each having 3 complementary
rings, whereby the material processed passes through 9 shear gaps
or stages upon traversing the HSD. Alternatively, each of three
generators may comprise four rings, whereby the processed material
passes through 12 shear gaps or stages upon passing through the
HSD. In some embodiments, the stator(s) are adjustable to obtain
the desired shear gap between the rotor and the stator of each
generator (rotor/stator set). Each generator may be driven by any
suitable drive system configured for providing the desired
rotation.
[0059] In some embodiments, the HSD comprises a single stage
dispersing chamber (i.e., a single rotor/stator combination; a
single high shear generator). In some embodiments, HSD 140/340 is a
multiple stage inline disperser and comprises a plurality of
generators. In certain embodiments, the HSD comprises at least two
generators. In other embodiments, HSD 140/340 comprises at least 3
generators. In some embodiments, HSD 140/340 is a multistage mixer
whereby the shear rate (which varies proportionately with tip speed
and inversely with rotor/stator gap width) varies with longitudinal
position along the flow pathway, as further described
hereinbelow.
[0060] According to this disclosure, at least one surface within
HSD 140/340 may be made of, impregnated with, or coated with a
catalyst that is suitable for assisting the desired component
extraction, for example converting caustic soda to sodium
bicarbonate. Further description is provided in U.S. patent
application Ser. No. 12/476,415, which is hereby incorporated
herein by reference for all purposes not contrary to this
disclosure.
[0061] In some embodiments, the minimum clearance (shear gap width)
between the stator and the rotor is in the range of from about
0.025 mm (0.001 inch) to about 3 mm (0.125 inch). The shear gap may
be in the range of from about 5 micrometers (0.0002 inch) and about
4 mm (0.016 inch). In embodiments, the shear gap is in the range of
5, 4, 3, 2 or 1 .mu.m. In some embodiments, the minimum clearance
(shear gap width) between the stator and the rotor is in the range
of from about 1 .mu.m (0.00004 inch) to about 3 mm (0.012 inch). In
some embodiments, the minimum clearance (shear gap width) between
the stator and the rotor is less than about 10 .mu.m (0.0004 inch),
less than about 50 .mu.m (0.002 inch), less than about 100 .mu.m
(0.004 inch), less than about 200 .mu.m (0.008 inch), less than
about 400 .mu.m (0.016 inch). In certain embodiments, the minimum
clearance (shear gap width) between the stator and rotor is about
1.5 mm (0.06 inch). In certain embodiments, the minimum clearance
(shear gap width) between the stator and rotor is about 0.2 mm
(0.008 inch). In certain configurations, the minimum clearance
(shear gap) between the rotor and stator is at least 1.7 mm (0.07
inch). The shear rate produced by the HSD may vary with
longitudinal position along the flow pathway. In some embodiments,
the rotor is set to rotate at a speed commensurate with the
diameter of the rotor and the desired tip speed. In some
embodiments, the HSD has a fixed clearance (shear gap width)
between the stator and rotor. Alternatively, the HSD has adjustable
clearance (shear gap width).
[0062] Tip speed is the circumferential distance traveled by the
tip of the rotor per unit of time. Tip speed is thus a function of
the rotor diameter and the rotational frequency. Tip speed (in
meters per minute, for example) may be calculated by multiplying
the circumferential distance transcribed by the rotor tip, 2.pi.R,
where R is the radius of the rotor (meters, for example) times the
frequency of revolution (for example revolutions per minute, rpm).
The frequency of revolution may be greater than 250 rpm, greater
than 500 rpm, greater than 1000 rpm, greater than 5000 rpm, greater
than 7500 rpm, greater than 10,000 rpm, greater than 13,000 rpm, or
greater than 15,000 rpm. The rotational frequency, flow rate, and
temperature may be adjusted to get a desired product profile. If
channeling should occur, and reaction is inadequate, the rotational
frequency may be increased to minimize undesirable channeling.
Alternatively or additionally, high shear-treated product may be
introduced into a second or subsequent HSD.
[0063] HSD 140/340 may provide a tip speed in excess of 22.9 m/s
(4500 ft/min) and may exceed 40 m/s (7900 ft/min), 50 m/s (9800
ft/min), 100 m/s (19,600 ft/min), 150 m/s (29,500 ft/min), 200 m/s
(39,300 ft/min), or even 225 m/s (44,300 ft/min) or greater in
certain applications. For the purpose of this disclosure, the term
`high shear` refers to mechanical rotor stator devices (e.g.,
colloid mills or rotor-stator dispersers) that are capable of tip
speeds in excess of 5.1 m/s (1000 ft/min) or those values provided
above and require an external mechanically driven power device to
drive energy into the stream of products to be reacted. By
contacting the reactants with the rotating members, which can be
made from, coated with, or impregnated with stationary catalyst,
significant energy is transferred to the reaction. The energy
consumption of the HSD 140/340 will generally be very low.
[0064] In some embodiments, HSD 140/340 is capable of delivering at
least 300 L/h at a tip speed of at least 22.9 m/s (4500 ft/min).
The power consumption may be about 1.5 kW. HSD 140/340 combines
high tip speed with a very small shear gap to produce significant
shear on the material being processed. The amount of shear will be
dependent on the viscosity of the fluid in the HSD. Accordingly, a
local region of elevated pressure and temperature is created at the
tip of the rotor during operation of HSD 140/340. In some cases the
locally elevated pressure is about 1034.2 MPa (150,000 psi). In
some cases the locally elevated temperature is about 500.degree. C.
In some cases, these local pressure and temperature elevations may
persist for nano- or pico-seconds.
[0065] An approximation of energy input into the fluid (kW/L/min)
can be estimated by measuring the motor energy (kW) and fluid
output (L/min). As mentioned above, tip speed is the velocity
(ft/min or m/s) associated with the end of the one or more
revolving elements that is creating the mechanical force applied to
the fluid. In embodiments, the energy expenditure is at least about
1000 W/m.sup.3, 5000 W/m.sup.3, 7500 W/m.sup.3, 1 kW/m.sup.3, 500
kW/m.sup.3, 1000 kW/m.sup.3, 5000 kW/m.sup.3, 7500 kW/m.sup.3, or
greater. In embodiments, the energy expenditure of HSD 140/340 is
greater than 1000 watts per cubic meter of fluid therein. In
embodiments, the energy expenditure of HSD 140/340 is in the range
of from about 3000 W/m.sup.3 to about 7500 kW/m.sup.3. In
embodiments, the energy expenditure of HSD 140/340 is in the range
of from about 3000 W/m.sup.3 to about 7500 W/m.sup.3. The actual
energy input needed is a function of what reactions are occurring
within the HSD, for example, endothermic and/or exothermic
reaction(s), as well as the mechanical energy required for
dispersing and mixing feedstock materials. In some applications,
the degree of exothermic reaction(s) occurring within the HSD
mitigates some or substantially all of the reaction energy needed
from the motor input. When dispersing a gas in a liquid, the energy
requirements are significantly less than when all reactants are
liquid.
[0066] The shear rate is the tip speed divided by the shear gap
width (minimal clearance between the rotor and stator). The shear
rate generated in HSD 140/340 may be greater than 20,000 s.sup.-1.
In some embodiments the shear rate is at least 30,000 s.sup.-1 or
at least 40,000 s.sup.-1. In some embodiments the shear rate is
greater than 30,000 s.sup.-1. In some embodiments the shear rate is
at least 100,000 s.sup.-1. In some embodiments the shear rate is at
least 500,000 s.sup.-1. In some embodiments the shear rate is at
least 1,000,000 s.sup.-1. In some embodiments the shear rate is at
least 1,600,000 s.sup.-1. In some embodiments the shear rate is at
least 3,000,000 s.sup.-1. In some embodiments the shear rate is at
least 5,000,000 s.sup.-1. In some embodiments the shear rate is at
least 7,000,000 s.sup.-1. In some embodiments the shear rate is at
least 9,000,000 s.sup.-1. In embodiments where the rotor has a
larger diameter, the shear rate may exceed about 9,000,000
s.sup.-1. In embodiments, the shear rate generated by HSD 140/340
is in the range of from 20,000 s.sup.-1 to 10,000,000 s.sup.-1. For
example, in one application the rotor tip speed is about 40 m/s
(7900 ft/min) and the shear gap width is 0.0254 mm (0.001 inch),
producing a shear rate of 1,600,000 s.sup.-1. In another
application the rotor tip speed is about 22.9 m/s (4500 ft/min) and
the shear gap width is 0.0254 mm (0.001 inch), producing a shear
rate of about 901,600 s.sup.-1.
[0067] In some embodiments, HSD 140/340 comprises a colloid mill.
Suitable colloidal mills are manufactured by IKA.RTM. Works, Inc.
Wilmington, N.C. and APV North America, Inc. Wilmington, Mass., for
example. In some instances, HSD 140/340 comprises the DISPAX
REACTOR.RTM. of IKA.RTM. Works, Inc.
[0068] In some embodiments, each stage of the external HSD has
interchangeable mixing tools, offering flexibility. For example,
the DR 2000/4 DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc.
Wilmington, N.C. and APV North America, Inc. Wilmington, Mass.,
comprises a three stage dispersing module. This module may comprise
up to three rotor/stator combinations (generators), with choice of
fine, medium, coarse, and super-fine for each stage. This allows
for variance of shear rate along the direction of flow. In some
embodiments, each of the stages is operated with super-fine
generator.
[0069] In embodiments, a scaled-up version of the DISPAX.RTM.
reactor is utilized For example, in embodiments HSD 140/340
comprises a SUPER DISPAX REACTOR.RTM. DRS 2000. The HSD unit may be
a DR 2000/50 unit, having a flow capacity of 125,000 liters per
hour, or a DRS 2000/50 having a flow capacity of 40,000
liters/hour. Because residence time is increased in the DRS unit,
the fluid therein is subjected to more shear. Referring now to FIG.
4, there is presented a longitudinal cross-section of a suitable
device HSD 200 for use as HSD 140/340. HSD 200 of FIG. 4 is a
dispersing device comprising three stages or rotor-stator
combinations, 220, 230, and 240. The rotor-stator combinations may
be known as generators 220, 230, 240 or stages without limitation.
Three rotor/stator sets or generators 220, 230, and 240 are aligned
in series along drive shaft 250.
[0070] First generator 220 comprises rotor 222 and stator 227.
Second generator 230 comprises rotor 223, and stator 228. Third
generator 240 comprises rotor 224 and stator 229. For each
generator the rotor is rotatably driven by input 250 and rotates
about axis 260 as indicated by arrow 265. The direction of rotation
may be opposite that shown by arrow 265 (e.g., clockwise or
counterclockwise about axis of rotation 260). Stators 227, 228, and
229 may be fixably coupled to the wall 255 of HSD 200. As mentioned
hereinabove, each rotor and stator may comprise rings of
complementarily-shaped tips, leading to several shear gaps within
each generator.
[0071] As mentioned hereinabove, each generator has a shear gap
width which is the minimum distance between the rotor and the
stator. In the embodiment of FIG. 4, first generator 220 comprises
a first shear gap 225; second generator 230 comprises a second
shear gap 235; and third generator 240 comprises a third shear gap
245. In embodiments, shear gaps 225, 235, 245 have widths in the
range of from about 0.025 mm to about 10 mm. Alternatively, the
process comprises utilization of an HSD 200 wherein the gaps 225,
235, 245 have a width in the range of from about 0.5 mm to about
2.5 mm. In certain instances the shear gap width is maintained at
about 1.5 mm. Alternatively, the width of shear gaps 225, 235, 245
are different for generators 220, 230, 240. In certain instances,
the width of shear gap 225 of first generator 220 is greater than
the width of shear gap 235 of second generator 230, which is in
turn greater than the width of shear gap 245 of third generator
240. As mentioned above, the generators of each stage may be
interchangeable, offering flexibility. HSD 200 may be configured so
that the shear rate remains the same or increases or decreases
stepwise longitudinally along the direction of the flow 260.
[0072] Generators 220, 230, and 240 may comprise a coarse, medium,
fine, and super-fine characterization, having different numbers of
complementary rings or stages on the rotors and complementary
stators. Rotors 222, 223, and 224 and stators 227, 228, and 229 may
be toothed designs. Each generator may comprise two or more sets of
complementary rotor-stator rings. In embodiments, rotors 222, 223,
and 224 comprise more than 3 sets of complementary rotor/stator
rings.
[0073] HSD 140/340 may be a large or small scale device. In
embodiments, system 100/300 is used to process from less than 100
gallons per minute to over 5000 gallons per minute. In embodiments,
one or more HSD 140/340 processes at least 100, 500, 750, 900,
1000, 2000, 3000, 4000, 5000 gpm or more. Large scale units may
produce 1000 gal/h (24 barrels/h). The inner diameter of the rotor
may be any size suitable for a desired application. In embodiments,
the inner diameter of the rotor is from about 12 cm (4 inch) to
about 40 cm (15 inch). In embodiments, the diameter of the rotor is
about 6 cm (2.4 inch). In embodiments, the outer diameter of the
stator is about 15 cm (5.9 inch). In embodiments, the diameter of
the stator is about 6.4 cm (2.5 inch). In some embodiments the
rotors are 60 cm (2.4 inch) and the stators are 6.4 cm (2.5 inch)
in diameter, providing a clearance of about 4 mm. In certain
embodiments, each of three stages is operated with a super-fine
generator comprising a number of sets of complementary rotor/stator
rings.
[0074] HSD 200 is configured for receiving at inlet 205 a feed
mixture from line 110/310. The feed comprises bitumen or heavy
crude oil in the case of asphaltene removal or tailings in the case
of water recovery. The feed may comprise reactant gas or reactant
gas may be separately introduced into the HSD. Feed stream entering
inlet 205 is pumped serially through generators 220, 230, and then
240, such that a dispersion is produced. High shear-treated product
exits HSD 200 via outlet 210 (and lines 150/160 of FIGS. 1/2). The
rotors 222, 223, 224 of each generator rotate at high speed
relative to the fixed stators 227, 228, 229, providing a high shear
rate. The rotation of the rotors pumps fluid, such as the feed
stream entering inlet 205, outwardly through the shear gaps (and,
if present, through the spaces between the rotor teeth and the
spaces between the stator teeth), creating a localized high shear
condition. High shear forces exerted on fluid in shear gaps 225,
235, and 245 (and, when present, in the gaps between the rotor
teeth and the stator teeth) through which fluid flows process the
fluid and create high shear product. The product comprises a high
shear mixture (e.g. a dispersion) of reactant gas and feed. High
shear-treated product exits HSD 200 via high shear outlet 210 (line
150/350 of FIGS. 1/2).
[0075] Without wishing to be limited by theory, it is believed that
the high shear product at 210 may comprise an abundance of free
radicals. The shear provided by the high velocity may generate
numerous micronized or submicronized globules. The high velocity,
associated surface phenomenon and other dissociating forces may
generate the free radicals in the product. This high shear-treated
product is highly reactive and may remain in a reactive state for
substantial time periods, e.g. 30 minutes or more in some
instances, even upon exiting the HSD.
[0076] As mentioned above, in certain instances, HSD 200 comprises
a DISPAX REACTOR.RTM. of IKA.RTM. Works, Inc. Wilmington, N.C. and
APV North America, Inc. Wilmington, Mass. Several models are
available having various inlet/outlet connections, horsepower, tip
speeds, output rpm, and flow rate. Selection of the HSD will depend
on throughput selection, for example. IKA.RTM. model DR 2000/4, for
example, comprises a belt drive, 4M generator, PTFE sealing ring,
inlet flange 25.4 mm (1 inch) sanitary clamp, outlet flange 19 mm
(3/4 inch) sanitary clamp, 2 HP power, output speed of 7900 rpm,
flow capacity (water) approximately 300-700 L/h (depending on
generator), a tip speed of from 9.4-41 m/s (1850 ft/min to 8070
ft/min). Scale up may be performed by using a plurality of HSDs, or
by utilizing larger HSDs. Scale-up using larger models is readily
performed, and results from larger HSD units may provide improved
efficiency in some instances relative to the efficiency of
lab-scale devices. The large scale unit may be a DISPAX.RTM.
2000/unit. For example, the DRS 2000/5 unit has an inlet size of 51
mm (2 inches) and an outlet of 38 mm (1.5 inches).
[0077] In embodiments HSD 140/340 or portions thereof are
manufactured from refractory/corrosion resistant materials. For
example, sintered metals, INCONEL.RTM. alloys, HASTELLOY.RTM.
materials may be used. For example, when the mixture is or
comprises caustic the rotors, stators, and/or other components of
the HSD may be manufactured of refractory materials (e.g. sintered
metal) in various applications.
[0078] Separation Apparatus 160/360. As discussed hereinabove, the
high shear system comprises a separation apparatus 160/360
configured to separate a component from the high shear-treated
product stream introduced thereto via high shear-treated product
stream outlet line 150/360. Separation units 160/360 may be
selected from centrifuges, settling tanks, filtration units, and
the like, as known in the art. In embodiments, separation unit
160/360 comprises one or more centrifuges. Separation apparatus
160/360 comprises an outlet 170/370 for removed component and an
outlet for component-reduced product 180/380. Separation apparatus
160 may further comprise a gas outlet line 175 for removal of gas
from separation apparatus 160. A recycle line may fluidly connect
the gas outlet line of the separation apparatus with the HSD.
[0079] Separation unit 160/360 may be operable continuously,
semi-continuously, or batchwise. Separation apparatus 160/360 may
comprise one or more unit(s) configured in series or in parallel.
For parallel operation, outlet line 150/350 may divide to introduce
high shear-treated product into multiple units 160/360.
[0080] Settling Tank 390. As indicated in FIG. 2 and discussed
hereinabove, the high shear system may further comprise an
additional separation unit, such as settling tank 390 in the
embodiment of FIG. 2. High shear system 100/300 may comprise one or
more settling tanks 390. Settling tank 390 is any suitable
apparatus configured to provide a suitable residence time for the
separation of an oil phase from an aqueous phase. Settling tank(s)
390 comprises an outlet 385 for an aqueous phase and an outlet 395
for an oil phase.
[0081] Feed Source 305. As indicated in the embodiment of FIG. 2,
the high shear system may further comprise feed source 305. Feed
source 305 may comprise apparatus suitable for providing bitumen or
heavy crude to HSD 140 in applications in which the high shear
system is to be utilized for removal of asphaltenes or apparatus
suitable for providing tailings to HSD 340 in applications in which
the high shear system is to be utilized for enhanced water
recovery/bitumen extraction. In embodiments, feed source 305
comprises apparatus suitable for providing tailings conventionally
introduced into a tailings pond. In embodiments, feed source 305
comprises a tailings pond. In applications, feed source apparatus
comprises a combination of the equipment shown in FIG. 3. The feed
source may comprise, for example, one or more separation cells 24,
one or more coarse centrifuges 40, one or more fine centrifuges 46,
one or more secondary separation units 28 or a combination thereof.
Feed source apparatus 305 may further comprise one or more tumblers
18, one or more hydrotransport lines and/or one or more froth
breakers 34.
[0082] Heat Transfer Devices. Internal or external heat transfer
devices are also contemplated in variations of the system. For
example, the reactants may be preheated via any method known to one
skilled in the art. Some suitable locations for one or more such
heat transfer devices are upstream of the HSD, between the HSD and
flow line 150/350, and within or subsequent separation apparatus
160/360. HSD 140/340 may comprise an inner shaft which may be
cooled, for example water-cooled, to partially or completely
control the temperature within the HSD. Some non-limiting examples
of such heat transfer devices are shell, tube, plate, and coil heat
exchangers, as are known in the art.
[0083] Pumps. The high shear system may comprise one or more pumps
configured for either continuous or semi-continuous operation, and
may be any suitable pumping device that is capable of providing
controlled flow through HSD 140/340 and high shear system 100/300.
In applications the one or more pump provides greater than 202.65
kPa (2 atm) pressure or greater than 303.97 kPa (3 atm) pressure.
The one or more pump may be a Roper Type 1 gear pump, Roper Pump
Company (Commerce Georgia) Dayton Pressure Booster Pump Model
2P372E, Dayton Electric Co (Niles, Ill.) is one suitable pump.
Preferably, all contact parts of the pump comprise stainless steel,
for example, 316 stainless steel. In some embodiments of the
system, the one or more pump is capable of pressures greater than
about 2026.5 kPa (20 atm).
[0084] In embodiments, a high shear system as described in the
embodiment of FIG. 1 is incorporated into a hot water extraction
system as depicted in FIG. 3. For example, one or more high shear
system(s) may be incorporated into a hot water extraction process
at locations indicated with arrows A, B, C, D and E, or elsewhere
throughout an extraction system. In such embodiments, asphaltene
removal may be provided by fluidly connecting a bitumen line, such
as on line 20 (before or after pump 21) as indicated by arrows C
and D, on line 30 as indicated by arrow E, 32, 38, 44, or 48 into
HSD 140. A high shear system 100 may be incorporated as indicated
at arrow B. In embodiments, a high shear system as described in the
embodiment of FIG. 2 is incorporated into a hot water extraction
system as depicted in FIG. 3. In such embodiments, water may be
recovered from the tailings by introducing tailings from tailings
pond 52 (feed source 305) into high shear system 300 as indicated
at arrow A. In this manner, water may be more rapidly recovered and
recycled to tumbler 18 and bitumen recovery may be enhanced. In
embodiments, a high shear system(s) is incorporated at arrow C, D,
and/or E. Each of the locations could optionally have addition of
CO.sub.2 and/or other compounds that cause the asphaltene to drop
out after reacting in the high shear unit. One or more diluents,
such as, but not limited to naphtha and propane, may be added along
with heat at any point in the system/process to reduce viscosity
and aid in transporting the bitumen. Such diluents may subsequently
be removed and reused.
[0085] High Shear Method for Removing a Component from a Stream
Produced During Recovery and/or Processing of Heavy Crude Oil or
Bitumen. A method of removing a component from a stream produced
during recovery and/or treatment of heavy crude oil or bitumen will
now be described with respect to FIG. 4 which is a schematic of a
high shear method 400 of removing a desired component from a feed
according to an embodiment of this disclosure. Method 400 comprises
intimately contacting feed and gas to form a high shear-treated
product at 410 and separating a component from the high
shear-treated product at 420. For ease of description, a method of
removing asphaltenes from asphaltenic bitumen or heavy crude oil
will now be made separately from description of a method of
improving bitumen extraction.
[0086] Method of Improving Bitumen Extraction from Tar Sands. In
embodiments, a high shear method is provided for improving bitumen
extraction from tar sands. This method may be utilized to enhance
bitumen separation from inorganic materials (mostly sand and clay)
following excavation or extraction from the ground.
[0087] For example, with reference now to FIG. 3, which depicts a
prior art hot water bitumen processing system, hot water and a
conditioning agent or base (usually caustic soda; i.e. sodium
hydroxide) are added to the bitumen to aid separation of the
bitumen from the inorganic components. Other bases, such as sodium
sesquicarbonate, may also be utilized. (See, for example, U.S. Pat.
App. No. 2002/0104799 by Humphreys et al.) Hot water processing is
usually performed in large tumblers 16 to aid in mixing. The slurry
from the tumblers 16 is screened through screen 22 to separate the
larger debris and passed to a separating cell 24 where settling
time is provided to allow the slurry to separate. As the slurry
settles, the bitumen froth rises to the surface and the sand
particles and sediments fall to the bottom. A middle viscous sludge
layer, termed middlings, contains dispersed clay particles and some
trapped bitumen which is not able to rise due to the viscosity of
the sludge. Once the slurry has settled, the froth is skimmed off
via line 30 for froth treatment and the sediment layer is passed
via line 27 to a tailings pond 52. The middlings 26 may be fed to a
second stage 28 of froth floatation for further bitumen froth
recovery. Tailings from secondary separation 28 may be sent via
line 51 to tailings pond 52.
[0088] In other embodiments, a modified hot water extraction
process termed the hydrotransport process is used to mix tar sand
with hot water and caustic at the mine site and the resultant
slurry is transported to the extraction unit 24 in a large pipe.
During the hydrotransport tar sand is conditioned and the bitumen
is aerated to form a froth. The hydrotransport system replaces the
manual or mechanical transport of the tar sands to the extraction
unit and eliminates the need for tumblers 16.
[0089] The bitumen froth in line 30 from either process contains
bitumen, solids and trapped water. The solids which are present in
the froth are in the form of clays, silt and some sand. From the
separating cell 24 the froth is passed via a line 30 to a defrother
vessel 34 where the froth is heated and broken to remove the air.
Naphtha is then added via line 33 to cause a reduction in the
density of the bitumen, facilitating separation of the bitumen from
the water by means of a subsequent centrifuge treatment. The
centrifuge treatment first includes a gross centrifuge separation
in coarse centrifuge 40 followed by fine centrifuge 46. The bitumen
collected from the centrifuge treatment 48 may contain less than 2%
water and solids and can be passed to the refinery for upgrading.
The water and solids released during the centrifuge treatment and
extracted from coarse centrifuge 40 via line 42 and extracted from
fine centrifuge 46 via line 50 may also be passed to the tailings
pond.
[0090] Typically, the tailings in a conventional tailing pond
comprise a sludge of caustic soda, sand and water with some
bitumen. During the initial years of residence time, some settling
takes place in the upper layer of the pond, releasing some of the
trapped water. The water released from the ponds can be recycled
back into the hot water process. The major portion of the tailings
remains as sludge indefinitely. The sludge contains some bitumen
and high percentages of solids, mainly in the form of suspended
silt and clay.
[0091] The tailings ponds are costly to build and maintain. The
size of the ponds and their characteristic caustic condition
creates serious environmental problems. In addition, environmental
concerns exist over the large quantity of water which is required
for extraction and which remains locked in the tailings pond after
use.
[0092] It is known that sludge is formed in the initial
conditioning of the tar sand, when the caustic soda attacks the
sand and clay particles. The caustic soda causes the clays to swell
and disburse into platelets which remain dispersed, inhibiting
settling. These platelets are held in suspension and form the
gel-like sludge. Such sludge inhibits the floatation of the bitumen
froth in the extraction process. Expanding-type clays such as the
montmorillanite clays are particularly susceptible to caustic
attack. Because of the problems caused by sludge formation and the
low bitumen recovery available from highly viscous sludges, lower
grade tar sands containing high levels of expanding-type clays
cannot be treated satisfactorily using the conventional hot water
extraction process.
[0093] The disclosed extraction process allows a reduction in the
production of sludge and therefore an increase in the water
available for recycling. Such a process provides the possibility of
increased bitumen recovery from lower grade ores. According to this
embodiment, intimately contacting a feed with gas to form a high
shear-treated product 410 comprises intimately contacting a feed
comprising tailings with carbon dioxide gas to form a high
shear-treated product. The high shear contacting of the tailings
with carbon dioxide transforms the caustic soda added to the
bitumen mix to sodium carbonate and then to sodium bicarbonate,
enhancing the settling rate and facilitating separation of
recyclable water. Settling aids may be added at any point in the
process where settling needs to be enhanced. Settling aids such as
polyacrylate and polyacrylamide polymers and alum and their
application are known to those experienced in the art.
[0094] The CO.sub.2 can be of any source and need not be pure.
CO.sub.2 can be sourced from combustion off-gas such as boiler and
petrochemical plants with the added benefit of sequestering a known
greenhouse gas. CO.sub.2 may optionally be mixed with air to aid in
flotation where a froth formation is desirable. Addition of
frothing aids, such as surface active agents, is also contemplated
if enhanced froth formation is desired. Froth formation may aid
separation of more dense from less dense compounds by attaching
bubbles to the insoluble compounds in the bitumen mix.
Lignisulfonate and sulfosuccinate are among the known surface
active agents used to aid in froth formation. Many other suitable
compounds are known to those experienced in the art.
[0095] As discussed above, the feed (e.g. tailings) may be obtained
by any means known in the art, for example as described hereinabove
with respect to the prior art hot water process of FIG. 3. In this
embodiment, intimately mixing at 410 comprises subjecting the feed
mixture (tailings), which may be introduced from tailings pond 305,
to high shear in the presence of carbon dioxide, which may be
introduced via reactant gas line 320 or may be introduced directly
into HSD 340, to produce a high shear-treated product. With respect
to FIG. 2, the high shear-treated stream exiting HSD 340 via line
350 may be in the form of a dispersion of carbon dioxide bubbles in
the tailings. The bubbles may have a mean diameter in the micron or
submicron range, may have a mean diameter of less than about 1
.mu.m, less than 0.5 .mu.m, or less than 0.4 .mu.m. In embodiments,
subjecting the feed mixture to high shear comprises subjecting to a
shear rate of at least 10,000 s.sup.-1, at least 20,000 s.sup.-1,
at least 30,000 s.sup.-1, or higher, as further discussed
herein.
[0096] As mentioned above, subjecting the feed mixture and carbon
dioxide to high shear may produce a dispersion comprising carbon
dioxide dispersed throughout a liquid phase comprising tailings. In
embodiments, a dispersion comprising nanobubbles and/or
microbubbles of the reactant gas is formed. In embodiments, the
bubbles in the dispersion have an average diameter of less than or
about 5, 4, 3, 2 or 1 .mu.m. In embodiments, the bubbles in the
dispersion have an average particle diameter in the nanometer
range, the micron range, or the submicron range.
[0097] Referring now to FIG. 2, intimately mixing the feed mixture
and reactant gas at 410 comprises introducing the feed mixture into
HSD 340. The feed mixture may be pumped into HSD 340. Carbon
dioxide may be introduced into HSD 340 via one or more dispersible
gas lines 320 or may be introduced directly into HSD 340. As
discussed above, the reactant gas may be any suitable and available
gas stream comprising carbon dioxide. In embodiments, the reactant
gas is substantially pure carbon dioxide. In embodiments, the
reactant gas further comprises air, for example, to aid in
flotation and separation of oil. Reactant gas may be introduced
into line 310 via line 320 or may be introduced elsewhere
throughout high shear system 300. In embodiments, reactant gas is
introduced into line 310 via line 320. In embodiments, reactant gas
and feed comprising tailings are separately introduced directly
into HSD 340. The feed mixture may be pumped through line 310, to
build pressure and feed HSD 340, providing a controlled flow
throughout HSD 340 and high shear system 300. In some embodiments,
the pressure of the HSD inlet stream in line 310 is increased to
greater than 200 kPa (2 atm) or greater than about 300 kPa (3
atmospheres). In this way, high shear system 300 may combine high
shear with pressure to enhance production of bicarbonate and
separation and recovery of water.
[0098] Within high shear device 340, the feed comprising tailings
is intimately contacted with carbon dioxide. The temperature, shear
rate and/or residence time within HSD 340 may be controlled to
effect desired reaction and provide a sufficient but not excessive
amount of carbon dioxide. Desirably, the amount of carbon dioxide
introduced into the HSD is sufficient such that the pH of the
solution drops to below 6. In embodiments, the feed has a pH of
about 10 and the pH of the high shear-treated stream is less than
about 6, such that solids and oil are easily removed from the water
via centrifuge 360 and settling tank 395, respectively. It is noted
that shearing in the presence of air (present in the system or
introduced thereto along with reactant carbon dioxide gas) may also
enhance the flotation of the oil in settling tank 390. In some
aspects of the present invention the high shear device will cause
formation of micelles due to the presence of surface active agents
in the bitumen mix. Micelle formation may aid in bitumen mix flow
and will be broken once water is removed.
[0099] In an exemplary embodiment, the high shear device comprises
a commercial disperser such as IKA.RTM. model DR 2000/4, a high
shear, three stage dispersing device configured with three rotors
in combination with stators, aligned in series, as described above.
The disperser is operated to subject the contents to high shear.
The rotor/stator sets may be configured as illustrated in FIG. 4,
for example. In such an embodiment, the feed comprising tailings
enters high shear device 340 via line 310 and enters a first stage
rotor/stator combination having circumferentially spaced first
stage shear openings. The coarse mixture exiting the first stage
enters the second rotor/stator stage, which has second stage shear
openings. The mixture emerging from the second stage enters the
third stage rotor/stator combination having third stage shear
openings. The rotors and stators of the generators may have
circumferentially spaced complementarily-shaped rings. A high
shear-treated product exits the high shear device via outlet 210
(line 350 in FIG. 2).
[0100] In some embodiments, the shear rate increases stepwise
longitudinally along the direction of the flow 260, or going from
an inner set of rings of one generator to an outer set of rings of
the same generator. In other embodiments, the shear rate decreases
stepwise longitudinally along the direction of the flow, 260, or
going from an inner set of rings of one generator to an outer set
of rings of the same generator (outward from axis 200). For
example, in some embodiments, the shear rate in the first
rotor/stator stage is greater than the shear rate in subsequent
stage(s). For example, in some embodiments, the shear rate in the
first rotor/stator stage is greater than or less than the shear
rate in a subsequent stage(s). In other embodiments, the shear rate
is substantially constant along the direction of the flow, with the
stage or stages being the same. If HSD 340 includes a PTFE seal,
for example, the seal may be cooled using any suitable technique
that is known in the art. The HSD may comprise a shaft in the
center which may be used to control the temperature within HSD
340.
[0101] The rotor(s) of HSD 340 may be set to rotate at a speed
commensurate with the diameter of the rotor and the desired tip
speed. As described above, the HSD (e.g., colloid mill or toothed
rim disperser) has either a fixed clearance between the stator and
rotor or has adjustable clearance.
[0102] In some embodiments, HSD 340 delivers at least 300 L/h at a
nominal tip speed of at least 22 m/s (4500 ft/min), 40 m/s (7900
ft/min), and which may exceed 225 m/s (45,000 ft/min) or greater.
The power consumption may be about 1.5 kW or higher as desired.
Although measurement of instantaneous temperature and pressure at
the tip of a rotating shear unit or revolving element in HSD 340 is
difficult, it is estimated that the localized temperature seen by
the intimately mixed reactants may be in excess of 500.degree. C.
and at pressures in excess of 500 kg/cm.sup.2 under high shear
conditions.
[0103] Conditions of temperature, pressure, space velocity, and/or
ratio of reactant gas to tailings may be adjusted to effect
substantially complete conversion of caustic in the tailings to
bicarbonate, enhancing subsequent component separation. The global
temperature and/or the temperature of the feed mixture introduced
into HSD 340 may be in the range of from about 5.degree. C. to
about 95.degree. C. In embodiments, the global temperature is
ambient temperature. In embodiments, the global operating
temperature is room temperature.
[0104] The residence time within HSD 340 is typically low. For
example, the residence time can be in the millisecond range, can be
about 10, 20, 30, 40, 50, 60, 70, 80, 90 or about 100 milliseconds,
can be about 100, 200, 300, 400, 500, 600, 700, 800, or about 900
milliseconds, can be in the range of seconds, or can be any range
thereamong.
[0105] As mentioned above, intimately mixing the feed mixture
comprising tailings with the carbon dioxide may comprise running
the feed mixture through one or more HSDs 340. Intimately mixing
the feed mixture with carbon dioxide at 410 may comprise running
the feed mixture through two or more HSDs 340, in series or in
parallel. Intimately mixing the feed mixture with carbon dioxide
may comprise running the feed mixture through three or more HSDs
340, in series and/or in parallel. Additional carbon dioxide may be
introduced into each subsequent HSD.
[0106] In this embodiment, separating a component from the high
shear-treated product at 420 comprises introducing the high
shear-treated stream into a centrifuge 360. Centrifuge 360 is
operated to separate solids from liquid. Solids are removed from
centrifuge 360 via solids outlet line 370. Separating a component
from the high shear-treated product at 420 further comprises
introducing the solids-reduced product into settling tank 390 via
line 380. Within settling tank 390, an aqueous phase 385 is
separated from an oil phase 395. The oil phase in line 395 may be
combined with product bitumen in line 30 or 48 of FIG. 3, for
example, when high shear system 300 is incorporated into such a hot
water caustic bitumen extraction process.
[0107] The high shear contacting of the tailings with carbon
dioxide reduces settling times for the sludge (tailings). When
carbon dioxide is added with shear, the caustic present in the
water from the tailings gets converted to sodium bicarbonate. As
disclosed in U.S. Pat. No. 5,626,743, which is hereby incorporated
herein by reference for all purposes not contrary to this
disclosure, the clay settles faster in the presence of bicarbonate
than caustic. The shear and carbon dioxide forces the oil out of
the clay. The oil may be floated to the top of settling tank 390
and removed, for example, skimmed off the surface. The presence of
air may aid in the flotation of oil in settling tank 390. The water
removed via line 385 may be sent for further treatment, for example
to a bio-pond, prior to discharge or may be recycled to the bitumen
extraction process, minimizing the amount of fresh water needed for
processing relative to conventional methods.
[0108] In embodiments, the water removed via line 385 comprises
less than 1 wt %, less than 0.5 wt %, or less than 0.1 wt % TSS.
This water may be aerated, treated and discharged or recycled back
to process.
[0109] Method of Removing Asphaltenes from Heavy Crude Oil/Bitumen.
The high shear method will now be described with reference to the
removal of asphaltenes from asphaltenic oil. The asphaltenic oil
may comprise heavy crude oil or bitumen. Description of this method
will now be provided with reference to FIGS. 1 and 3. Asphaltenes
are complex organic materials that are arranged in stacked,
multi-ring structures that posses very high boiling point
polyaromatic hydrocarbons. The exact molecular structure of
asphaltenes is not known because of the complexity of the
asphaltene molecules. Therefore, the definitions of asphaltenes are
based on their solubility. Generally, asphaltenes are the fraction
of oil that is insoluble in paraffinic solvents such as n-heptane
or n-pentane, and soluble in aromatic solvents such as benzene or
toluene. Asphaltenes contain nitrogen, sulfur and oxygen atoms in
addition to carbon and hydrogen atoms within the repeating unit.
Asphaltenes are not truly soluble in crude oil. They exist as 35-40
micron platelets that are maintained in suspension by materials
known as maltenes and resins. When stabilizing factors are altered,
the asphaltenes coalesce under certain pressure, temperature and
compositional conditions. It is generally understood that the API
gravity goes down with increasing asphaltene content.
[0110] The major destabilizing forces for asphaltenes, as described
in the book Asphaltene and Asphalts (Yen and Chilingar--1994),
include CO.sub.2 injection, miscible flooding, pH shift, mixing of
crude streams, and the presence of incomplete organic chemicals.
The role of carbon dioxide in destabilizing asphaltene-crude oil is
well-documented. Some degree of asphaltene precipitation is noted
in wells in every CO.sub.2 flooding operation, with the most
notable asphaltene precipitation being in the well-bore and the
pump regions. Miscible flooding causes asphaltene destabilization
because straight chain hydrocarbons have less affinity for
asphaltene ring structures. In analytical tests, heptane is
normally used in crude oil to reject asphaltene. A shift in pH can
be invoked by CO.sub.2, mineral acids or naturally occurring acids
and can destabilize asphaltenes. Asphaltene precipitation can also
be induced by high shear or perturbation caused by cavitations in
some pumps or mixing manifolds. Some chemicals, such as methyl
alcohol which does not have an aromatic ring, may selectively
attract or wet the maltenes or resins and cause agglomeration of
asphaltenes.
[0111] In this embodiment, the high shear method is utilized to
effect enhanced removal of asphaltenes from asphaltenic oil by
subjecting the asphaltenic oil to high shear in the presence of
carbon dioxide. In this embodiment, intimately contacting feed with
gas to form high shear-treated product 410 comprises intimately
mixing feed comprising asphaltenic heavy crude oil and/or bitumen
(i.e., heavy crude oil comprising asphaltenes and/or bitumen
comprising asphaltenes) with carbon dioxide. The intimate
contacting may be performed substantially as described above. With
reference to FIG. 1, bitumen or heavy crude oil is introduced into
HSD 140 along with carbon dioxide. Water may be added to HSD 140 in
some applications. High shear-treated product exits HSD 140 via HSD
outlet line 150.
[0112] Specifically, the feed (bitumen or heavy crude oil) may be
obtained by any means known in the art, for example a bitumen feed
may be obtained as described hereinabove with respect to the prior
art hot water bitumen extraction process of FIG. 3. In this
embodiment, intimately mixing at 410 comprises subjecting the feed
mixture (comprising bitumen or heavy crude oil) to high shear in
the presence of carbon dioxide, which may be introduced via
reactant gas line 120, may already be present in the feed, or may
be introduced into the feed prior to introduction of the feed into
HSD 140, to produce a high shear-treated product. As indicated in
FIG. 1, water may be introduced into HSD 140 via separate inlet
line 130 or may be combined with or present in feed 110. With
respect to FIG. 1, the high shear treated stream exiting HSD 140
via line 150 may be in the form of a dispersion of carbon dioxide
in the feed or feed/water mixture. In embodiments, subjecting the
feed mixture to high shear comprises subjecting to a shear rate of
at least 10,000 s.sup.-1, at least 20,000 s.sup.-1, at least 30,000
s.sup.-1, or higher, as further discussed herein.
[0113] Referring again to FIG. 1, intimately mixing the feed
mixture and reactant gas at 410 comprises introducing the feed
mixture into HSD 140. The feed mixture may be pumped into HSD 140.
Carbon dioxide may be introduced into HSD 140 via one or more
dispersible gas lines 120 or may be introduced directly into HSD
140, as indicated. As discussed above, the reactant gas may be any
suitable and available gas stream comprising carbon dioxide. In
embodiments, the reactant gas is substantially pure carbon dioxide.
Reactant gas may be introduced into line 110 or may be introduced
elsewhere throughout high shear system 100. In embodiments,
reactant gas is introduced into line 110 prior to introduction into
HSD 140. In embodiments, reactant gas and feed comprising
asphaltenic oil from which asphaltenes are to be removed are
separately introduced directly into HSD 140. The feed mixture may
be pumped through line 110, to build pressure and feed HSD 140,
providing a controlled flow throughout high shear device (HSD) 140
and high shear system 100. In some embodiments, the pressure of the
HSD inlet stream in line 110 is increased to greater than 200 kPa
(2 atm) or greater than about 300 kPa (3 atmospheres). In this way,
high shear system 100 may combine high shear with pressure to
enhance destabilization and subsequent separation of asphaltenes
from the feed oil.
[0114] Within high shear device 140, the feed comprising
asphaltenic oil is intimately mixed with carbon dioxide. The
temperature, shear rate and/or residence time within HSD 140 may be
controlled to effect desired asphaltene destabilization and provide
a sufficient but not excessive amount of carbon dioxide.
Experiments may be performed to determine the minimum amount of
carbon dioxide needed to effect a desired degree of asphaltene
removal.
[0115] Subjecting the feed mixture and carbon dioxide to high shear
may produce a dispersion comprising carbon dioxide dispersed
throughout a liquid phase. In embodiments, a dispersion comprising
nanobubbles and/or microbubbles of the reactant gas is formed. In
embodiments, the bubbles in the dispersion have an average diameter
of less than or about 5, 4, 3, 2 or 1 .mu.m. In embodiments, the
bubbles in the dispersion have an average particle diameter in the
nanometer range, the micron range, or the submicron range. In
embodiments, hydrogen is also introduced to the high shear device
to enable hydrogenation, in a manner similar to that provided in
U.S. Pat. App. No. 61/145,839, which is hereby incorporated herein
by reference. Addition of hydrogen may aid in reducing viscosity
and/or stabilizing the bitumen.
[0116] In an exemplary embodiment, the high shear device comprises
a commercial disperser such as IKA.RTM. model DR 2000/4, a high
shear, three stage dispersing device configured with three rotors
in combination with stators, aligned in series, as described above.
The disperser is operated to subject the contents to high shear.
The rotor/stator sets may be configured as illustrated in FIG. 4,
for example. In such an embodiment, the feed comprising asphaltenic
oil enters high shear device 140 via line 110 and enters a first
stage rotor/stator combination having circumferentially spaced
first stage shear openings. The coarse mixture exiting the first
stage enters the second rotor/stator stage, which has second stage
shear openings. The mixture emerging from the second stage enters
the third stage rotor/stator combination having third stage shear
openings. The rotors and stators of the generators may have
circumferentially spaced complementarily-shaped rings. A high
shear-treated product exits the high shear device via outlet 210
(line 150 in FIG. 1).
[0117] In some embodiments, the shear rate increases stepwise
longitudinally along the direction of the flow 260, or going from
an inner set of rings of one generator to an outer set of rings of
the same generator. In other embodiments, the shear rate decreases
stepwise longitudinally along the direction of the flow, 260, or
going from an inner set of rings of one generator to an outer set
of rings of the same generator (outward from axis 200). For
example, in some embodiments, the shear rate in the first
rotor/stator stage is greater than the shear rate in subsequent
stage(s). For example, in some embodiments, the shear rate in the
first rotor/stator stage is greater than or less than the shear
rate in a subsequent stage(s). In other embodiments, the shear rate
is substantially constant along the direction of the flow, with the
stage or stages being the same. If HSD 140 includes a PTFE seal,
for example, the seal may be cooled using any suitable technique
that is known in the art. The HSD may comprise a central shaft
which may be used to control the temperature within HSD 140.
[0118] The rotor(s) of HSD 140 may be set to rotate at a speed
commensurate with the diameter of the rotor and the desired tip
speed. As described above, the HSD (e.g., colloid mill or toothed
rim disperser) has either a fixed clearance between the stator and
rotor or has adjustable clearance.
[0119] In some embodiments, HSD 140 delivers at least 300 L/h at a
nominal tip speed of at least 22 m/s (4500 ft/min), 40 m/s (7900
ft/min), and which may exceed 225 m/s (45,000 ft/min) or greater.
The power consumption may be about 1.5 kW or higher as desired.
Although measurement of instantaneous temperature and pressure at
the tip of a rotating shear unit or revolving element in HSD 140 is
difficult, it is estimated that the localized temperature seen by
the intimately mixed reactants may be in excess of 500.degree. C.
and at pressures in excess of 500 kg/cm.sup.2 under high shear
conditions.
[0120] Conditions of temperature, pressure, space velocity, and/or
ratio of reactant gas to feed oil may be adjusted to effect
substantially complete destabilization and subsequent removal of
asphaltenes. The global temperature and/or the temperature of the
feed mixture introduced into HSD 140 may be in the range of from
about 10.degree. C. to about 200.degree. C. In embodiments, the
global temperature is ambient temperature. In embodiments, the
global operating temperature is room temperature.
[0121] The residence time within HSD 140 is typically low. For
example, the residence time can be in the millisecond range, can be
about 10, 20, 30, 40, 50, 60, 70, 80, 90 or about 100 milliseconds,
can be about 100, 200, 300, 400, 500, 600, 700, 800, or about 900
milliseconds, can be in the range of seconds, or can be any range
thereamong.
[0122] As mentioned above, intimately mixing the feed mixture
comprising asphaltenic oil with the carbon dioxide may comprise
running the feed mixture through one or more HSDs 140. Intimately
mixing the feed mixture with carbon dioxide at 410 may comprise
running the feed mixture through two or more HSDs 140, in series or
in parallel. Intimately mixing the feed mixture with carbon dioxide
may comprise running the feed mixture through three or more HSDs
140, in series and/or in parallel. Additional carbon dioxide may be
introduced into each subsequent HSD.
[0123] In this embodiment, separating a component from the high
shear-treated product 420 comprises introducing the high
shear-treated product in line 150 into centrifuge 160. The high
shear and the presence of CO.sub.2 destabilize the asphaltenes,
which are easily separated from the oil via operation of centrifuge
160. Asphaltenes are removed from centrifuge 160 via outlet line
170 and may be sent for further processing as known in the art. Oil
from which asphaltenes have been removed (i.e. lighter crude oil or
asphaltene-reduced bitumen) is removed from centrifuge 160 via line
180. Due to the removal of asphaltenes, the API gravity of the
product oil in line 180 is generally greater than the API gravity
of the feed oil (e.g. asphaltenic bitumen or heavy crude oil)
introduced into high shear system 100 via feed line 110. In
embodiments, the API gravity of the oil in line 180 is greater than
about 7, greater than about 12, greater than about 15, or greater
than about 17. In embodiments, the API gravity of the feed in line
110 is less than about 10, less than about 7 or less than about 5.
Transportation of the asphaltene-reduced oil removed from
centrifuge 160 via line 180 is thus facilitated relative to
transport of the heavy crude oil or asphaltic bitumen introduced
into high shear system 100 via line 110. Carbon dioxide may be
removed from centrifuge 160 via gas outlet line 175. The carbon
dioxide may be recycled to HSD 140.
[0124] Desirably, this process is performed subsequent removal of
the majority of the clay, sand and other inorganics from the tar
sands. For example, as indicated in FIG. 3, HSD 140 may be
positioned downstream of one or more tumblers 18, downstream of one
or more screens 22, downstream of one or more separation cells 24,
and/or downstream of one or more secondary separation cells 28.
[0125] In embodiments, the operating temperature and pressure for
asphaltene removal are mild. In embodiments, the operating
temperature throughout high shear system 300 and/or HSD 140 is in
the range of from about room temperature to about 100.degree. C. In
embodiments, the operating pressure is in the range if from about 0
to about 60 psig. The resulting liquid oil in product line 180 can
be easily transported in pipelines with or without diluents.
Advantages to this method of asphaltene removal may include: (1) a
reduction in distillation cost of conventionally-used diluent; (2)
a reduction in transportation cost of diluents; (3) removal of
sand, clay and other inorganic contaminants from feed (e.g. heavy
crude oil) along with removal of asphaltenes; (4) asphaltene
removal in situ; (5) concomitant reduction in heavy metals; (6)
reduction in pipeline fouling and cleaning costs due to sand
asphaltene precipitation; (7) partial sulfur removal; and (8)
operation in the presence or absence of water (as mentioned
hereinabove, conventional solvent deasphalting is intolerant to the
presence of water).
[0126] In embodiments, the product oil exiting the high shear
system comprises less than 10 wt %, 5 wt % , 3 wt %, or 1 wt % of
impurities selected from asphaltenes, sand, silt and other solids.
In embodiments, the product oil in line 180 comprises from about 95
to about 99 wt % bitumen, from about 5 wt % to about 1 wt % water,
and from about 2% to about 0.5 wt % solids. In embodiments, the
product oil in line 180 comprises less than 10 wt %, 3 wt %, or 1
wt % asphaltenes. In embodiments, the product oil in line 180
comprises less than 1 wt %, 0.5 wt %, or 0.1 wt % solids, such as
silt, sand, fines and other particulate matter (TDS). In
embodiments, the product oil in line 180 comprises less than 5 wt
%, 2 wt %, or 1 wt % water. In embodiments, the product oil has an
API gravity of greater than 8, 10, or 15. In embodiments, the feed
comprising bitumen or heavy crude oil introduced into HSD via feed
line 110 has an API gravity in the range of from about 7 to about
10, from about 10 to about 15, or from about 15 to about 25. In
embodiments, utilization of the disclosed system and method
provides at least about a 30, 40, 50, 60, 70, or 80% reduction in
the amount of impurities (e.g., asphaltenes, solids, water or heavy
metals) in the bitumen or heavy crude oil fed to HSD 140 via line
110. Concomitantly, utilization of the disclosed system and method
may provide a significant cost savings by providing for less
required downstream purification equipment, reduced-size equipment,
and/or reduced down-time for cleaning due to plugging, etc. The
system and method may be operable to provide greater than 5, 10, or
20 tons/h of component reduced oil in line 180, 380 and/or 395.
[0127] Multiple Pass Operation. In the embodiments shown in FIGS. 1
and 2, the systems are configured for single pass operation.
However, the output of HSD 140/340 may be run through a subsequent
HSD. In some embodiments, it may be desirable to pass the contents
of flow line 150/350, flow line 180/380 or a fraction thereof,
through HSD 140/340 during a second pass. In this case, at least a
portion of the contents of flow line 150/350 or 180/380 may be
recycled back into HSD 140/340. Additional reactant gas (e.g.,
carbon dioxide) may be injected via line 120/320 into line 110, or
may be added directly into the HSD. Due to the rapidity of the
interactions within the HSD, multiple pass operation may not be
necessary or desirable.
[0128] Multiple HSDs. In embodiments, high shear-treated product in
HSD outlet line 150/350 or centrifuge 160/360 product outlet line
180/380 is fed into a second HSD. In some embodiments, two or more
HSDs like HSD 140/340, or configured differently, are aligned in
series, and are used to promote further interaction. In
embodiments, the reactants pass through multiple HSDs 140/340 in
serial or parallel flow. In embodiments, a second HSD is positioned
upstream or downstream of centrifuge 160/360, whereby the high
shear-treated product exiting HSD 140/340 or exiting centrifuge
160/360 via product outlet line 180/380 is introduced into a
subsequent HSD for further treatment. When multiple HSDs are
operated in series, additional carbon dioxide-containing gas may be
injected into the inlet feedstream of each HSD. For example,
additional reactant gas may be introduced into a second or
subsequent HSD. In some embodiments, multiple HSDs are operated in
parallel, and the outlet products therefrom are introduced into one
or more flow lines 150/350.
[0129] Features. Without wishing to be limited to a particular
theory, it is believed that the level or degree of high shear
mixing may be sufficient to increase rates of mass transfer and
also produce localized non-ideal conditions (in terms of
thermodynamics) that enable reactions to occur that would not
otherwise be expected to occur based on Gibbs free energy
predictions and/or increase the rate or extent of expected
reactions. Localized non ideal conditions are believed to occur
within the HSD resulting in increased temperatures and pressures
with the most significant increase believed to be in localized
pressures. The increases in pressure and temperature within the HSD
are instantaneous and localized and quickly revert back to bulk or
average system conditions once exiting the HSD. Without wishing to
be limited by theory, in some cases, the HSD may induce cavitation
of sufficient intensity to dissociate one or more of the reactants
into free radicals, which may intensify a chemical reaction or
allow a reaction to take place at less stringent conditions than
might otherwise be required. Cavitation may also increase rates of
transport processes by producing local turbulence and liquid
micro-circulation (acoustic streaming). An overview of the
application of cavitation phenomenon in chemical/physical
processing applications is provided by Gogate et al., "Cavitation:
A technology on the horizon," Current Science 91 (No. 1): 35-46
(2006). The HSD of certain embodiments of the present system and
methods may induce cavitation whereby one or more reactant is
dissociated into free radicals, which then react. In embodiments,
the extreme pressure at the tips of the rotors/stators leads to
liquid phase reaction, and no cavitation is involved.
[0130] Various dimensions, sizes, quantities, volumes, rates, and
other numerical parameters and numbers have been used for purposes
of illustration and exemplification of the principles of the
invention, and are not intended to limit the invention to the
numerical parameters and numbers illustrated, described or
otherwise stated herein. Likewise, unless specifically stated, the
order of steps is not considered critical. The different teachings
of the embodiments discussed herein may be employed separately or
in any suitable combination to produce desired results.
[0131] While preferred embodiments of the invention have been shown
and described, modifications thereof can be made by one skilled in
the art without departing from the spirit and teachings of the
invention. The embodiments described herein are exemplary only, and
are not intended to be limiting. Many variations and modifications
of the invention disclosed herein are possible and are within the
scope of the invention. Where numerical ranges or limitations are
expressly stated, such express ranges or limitations should be
understood to include iterative ranges or limitations of like
magnitude falling within the expressly stated ranges or limitations
(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater
than 0.10 includes 0.11, 0.12, 0.13, and so forth). Use of the term
"optionally" with respect to any element of a claim is intended to
mean that the subject element is required, or alternatively, is not
required. Both alternatives are intended to be within the scope of
the claim. Use of broader terms such as comprises, includes,
having, etc. should be understood to provide support for narrower
terms such as consisting of, consisting essentially of, comprised
substantially of, and the like.
[0132] Accordingly, the scope of protection is not limited by the
description set out above but is only limited by the claims which
follow, that scope including all equivalents of the subject matter
of the claims. Each and every claim is incorporated into the
specification as an embodiment of the present invention. Thus, the
claims are a further description and are an addition to the
preferred embodiments of the present invention. The disclosures of
all patents, patent applications, and publications cited herein are
hereby incorporated by reference, to the extent they provide
exemplary, procedural or other details supplementary to those set
forth herein.
* * * * *