U.S. patent application number 14/180136 was filed with the patent office on 2014-08-21 for method and apparatus for extracting bitumen from an oil sand stream.
This patent application is currently assigned to SHELL CANADA ENERGY. The applicant listed for this patent is SHELL CANADA ENERGY. Invention is credited to Gerhardus Willem COLENBRANDER, Julian Robert KIFT, Ingmar Hubertus Josephina PLOEMEN, Whip Clinton Galen THOMPSON.
Application Number | 20140231312 14/180136 |
Document ID | / |
Family ID | 51350386 |
Filed Date | 2014-08-21 |
United States Patent
Application |
20140231312 |
Kind Code |
A1 |
COLENBRANDER; Gerhardus Willem ;
et al. |
August 21, 2014 |
METHOD AND APPARATUS FOR EXTRACTING BITUMEN FROM AN OIL SAND
STREAM
Abstract
The present invention provides a method for extracting bitumen
from an oil sand stream, the method including the steps of: (a)
providing an oil sand stream; (b) contacting the oil sand stream
with a solvent thereby obtaining a first solvent-diluted oil sand
slurry; (c) screening the first solvent-diluted oil sand slurry,
thereby obtaining a first oversized material and a first undersized
material; (d) contacting the first oversized material with a
solvent thereby obtaining a second solvent-diluted oil sand slurry;
(e) screening the second solvent-diluted oil sand slurry, thereby
obtaining a second oversized material and a second undersized
material; (f) optionally filtering the first undersized material
obtained in step (c), thereby obtaining a solids-depleted stream
and a solids-enriched stream; (g) optionally removing solvent from
the solids-depleted stream obtained in step (f) thereby obtaining a
bitumen-enriched stream.
Inventors: |
COLENBRANDER; Gerhardus Willem;
(Amsterdam, NL) ; KIFT; Julian Robert; (Reno,
NV) ; PLOEMEN; Ingmar Hubertus Josephina; (Amsterdam,
NL) ; THOMPSON; Whip Clinton Galen; (Sparks,
NV) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL CANADA ENERGY |
Calgary |
|
CA |
|
|
Assignee: |
SHELL CANADA ENERGY
Calgary
CA
|
Family ID: |
51350386 |
Appl. No.: |
14/180136 |
Filed: |
February 13, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61766015 |
Feb 18, 2013 |
|
|
|
Current U.S.
Class: |
208/390 ;
196/14.52 |
Current CPC
Class: |
C10G 1/045 20130101 |
Class at
Publication: |
208/390 ;
196/14.52 |
International
Class: |
C10G 1/04 20060101
C10G001/04 |
Claims
1. A method for extracting bitumen from an oil sand stream, the
method comprising at least the steps of: (a) providing an oil sand
stream; (b) contacting the oil sand stream with a solvent thereby
obtaining a first solvent-diluted oil sand slurry; (c) screening
the first solvent-diluted oil sand slurry, thereby obtaining a
first oversized material and a first undersized material; (d)
contacting the first oversized material with a solvent thereby
obtaining a second solvent-diluted oil sand slurry; (e) screening
the second solvent-diluted oil sand slurry, thereby obtaining a
second oversized material and a second undersized material; (f)
optionally filtering the first undersized material obtained in step
(c), thereby obtaining a solids-depleted stream and a
solids-enriched stream; (g) optionally removing solvent from the
solids-depleted stream obtained in step (f) thereby obtaining a
bitumen-enriched stream.
2. The method according to claim 1, wherein the solvent in step (b)
comprises a non-aqueous solvent.
3. The method according to claim 1, wherein the solvent in step (d)
comprises a non-aqueous solvent.
4. The method according to claim 1, wherein the first undersized
material obtained in step (c) is combined with the second
undersized material obtained in step (e), before being filtered in
step (f).
5. An apparatus for performing the method according to claim 1, at
least comprising: a housing containing a first section, a second
section, a third section and a fourth section; the first section
having a first inlet for oil sand, a second inlet for a solvent and
an outlet for a first solvent-diluted oil sand slurry; the second
section having an inlet for the first solvent-diluted oil sand
slurry, a screen allowing a first undersized material to pass and
an outlet for a first oversized material; and the third section
having a first inlet for the first oversized material, a second
inlet for a solvent and an outlet for a second solvent-diluted oil
sand slurry; the fourth section having an inlet for the second
solvent-diluted oil sand slurry, a screen allowing a second
undersized material to pass and an outlet for a second oversized
material; wherein the first section, the second section, the third
section and the fourth section can rotate during use around a
common rotation axis (A-A').
6. The apparatus according to claim 5, wherein the screen of the
second section and the housing define an annular pathway arranged
around the screen for removing the first undersized material passed
through the screen.
7. The apparatus according to claim 5, wherein the screen of the
fourth section and the housing define an annular pathway arranged
around the screen for removing the second undersized material
passed through the screen.
8. The apparatus according to claim 6, wherein the annular pathway
is fluidly connected to an inlet of a filtration unit.
9. The apparatus according to claim 5, comprising a threshold
between the first section and second section.
10. The apparatus according to claim 5, comprising a threshold
between the third section and fourth section.
11. The apparatus according to claim 5, comprising an inner screen
which is concentrically arranged with respect to the screen of the
second section and the screen of the fourth section.
12. The apparatus according to claim 11, wherein the inner screen
connects the outlet of the first section to the outlet of the
fourth section.
Description
RELATED APPLICATIONS
[0001] This application claims the benefit of US Provisional
Application No. 61/766,015 filed Feb. 18, 2013, which is
incorporated herein by reference.
BACKGROUND
[0002] The present invention relates to a method for extracting
bitumen from an oil sand stream.
[0003] Various methods have been proposed in the past for the
recovery of bitumen (sometimes referred to as "tar" or "bituminous
material") from oil sands as found in various locations throughout
the world and in particular in Canada such as in the Athabasca
district in Alberta and in the United States such as in the Utah
oil sands. Typically, oil sand (also known as "bituminous sand" or
"tar sand") comprises a mixture of bitumen (in this context also
known as "crude bitumen", a semi-solid form of crude oil; also
known as "extremely heavy crude oil"), sand, clay minerals and
water. Usually, oil sand contains about 5 to 25 wt. % bitumen (as
meant according to the present invention), about 1 to 13 wt. %
water, the remainder being sand and clay particles.
[0004] As an example, it has been proposed and practiced at
commercial scale to recover the bitumen content from the oil sand
by mixing the oil sand with water and separating the sand from the
aqueous phase of the slurry formed.
[0005] Other methods have proposed non-aqueous extraction processes
to reduce the need for large quantities of process water.
[0006] A problem of known methods of extraction of bitumen from oil
sand is the handling of oil sand ore, in particular the bitumen
lumps being present therein. The breaking down of such bitumen
lumps takes a lot of time and requires long overall residence time
and large equipment.
[0007] It is an object of the present invention to improve the
handling of oil sand ore.
[0008] It is a further object of the present invention to provide a
more efficient handling of oil sand ore in an oil sand stream, in
particular when bitumen is to be extracted from the oil sand stream
using a non-aqueous solvent.
[0009] One or more of the above or other objects may be achieved
according to the present invention by providing a method for
extracting bitumen from an oil sand stream, the method comprising
at least the steps of: [0010] (a) providing an oil sand stream;
[0011] (b) contacting the oil sand stream with a solvent thereby
obtaining a first solvent-diluted oil sand slurry; [0012] (c)
screening the first solvent-diluted oil sand slurry, thereby
obtaining a first oversized material and a first undersized
material; [0013] (d) contacting the first oversized material with a
solvent thereby obtaining a second solvent-diluted oil sand slurry;
[0014] (e) screening the second solvent-diluted oil sand slurry,
thereby obtaining a second oversized material and a second
undersized material; [0015] (f) optionally filtering the first
undersized material obtained in step (c), thereby obtaining a
solids-depleted stream and a solids-enriched stream; [0016] (g)
optionally removing solvent from the solids-depleted stream
obtained in step (f) thereby obtaining a bitumen-enriched
stream.
[0017] The method according to the present invention provides a
surprisingly simple and elegant manner to handle oil sands ore in
an oil sand stream. It has surprisingly been found according to the
present invention that a large proportion of the bitumen lumps
break down quickly and can pass the screen in step (c) after only a
short contacting time in step (b). The remaining bitumen lumps are
subjected to further mixing and screening and, as the size of this
stream has been significantly reduced, smaller equipment can be
used.
[0018] An important advantage of the present invention is that it
allows a reduction in overall size requirement, and, in some
embodiments, in particular where the contacting and screening steps
are integrated in one device, a reduction in the number of rotary
seals and a reduction in the number of drive assemblies, when
compared to performing the mixing, screening operations in separate
devices.
[0019] A further advantage according to the present invention is
that coarse solids as present in the oil sand do not require to be
transported between separate devices for mixing, screening and
drying/solvent removal. The handling of such coarse solids is
already a challenge in conventional oil sand processes, but much
more difficult in case a non-aqueous solvent (which typically
comprises a volatile hydrocarbon) is to be used for extracting
bitumen from the oil sand.
[0020] According to the present invention, the providing of the oil
sand stream in step (a) can be done in various ways. Typically, oil
sand is reduced in size, e.g. by crushing, breaking and/or
grinding, to below a desired size upper limit Preferably, the oil
sand provided in step (a) has a particle size of less than 20 inch,
preferably less than 16 inch, more preferably less than 12 inch.
Also, the oil sand stream provided in step (a) is typically
subjected to a deoxygenation step; this is of particular relevance
if the solvent as used in step (b) is a flammable solvent.
[0021] In step (b), the oil sand is contacted with a solvent in the
first section thereby obtaining a first solvent-diluted oil sand
slurry. The person skilled in the art will understand that, in
particular when the solvent is recycled from a downstream point in
the process, it may contain some bitumen.
[0022] The solvent as used in the method of the present invention
may be selected from a wide variety of solvents, including water,
aromatic hydrocarbon solvents and saturated or unsaturated
aliphatic (i.e. non-aromatic) hydrocarbon solvents; aliphatic
hydrocarbon solvents may include linear, branched or cyclic alkanes
and alkenes and mixtures thereof. Preferably, the solvent in step
(b) comprises a non-aqueous solvent. Preferably, the solvent in
step (b) comprises an aliphatic hydrocarbon having from 3 to 9
carbon atoms per molecule, more preferably from 4 to 7 carbons per
molecule, or a combination thereof. Especially suitable solvents
are saturated aliphatic hydrocarbons such as propane, butane,
pentane, hexane, heptane, octane and nonane (including isomers
thereof), in particular butane, pentane, hexane and heptane. It is
preferred that the solvent in step (b) comprises at least 90 wt. %
of the aliphatic hydrocarbon having from 3 to 9 carbon atoms per
molecule, preferably at least 95 wt. %. Also, it is preferred that
in step (b) substantially no aromatic solvent (such as toluene or
benzene) is present, i.e. less than 5 wt. %, preferably less than 1
wt. %. Further it is preferred that a single solvent is used as
this avoids the need for a distillation unit or the like to
separate solvents. Also, it is preferred that the solvent has a
boiling point lower than that of the bitumen to facilitate easy
separation and recovery.
[0023] Furthermore, if desired, additional process fluids may be
added, such as water and/or agglomeration agents, for example to
aid in achieving desired slurry properties through agglomeration of
fine particles.
[0024] In step (c), the first solvent-diluted oil sand slurry is
screened, thereby obtaining a first oversized material and a first
undersized material. Typically, the first solvent-diluted oil sand
slurry screened or reduced in size to have a diameter below 5.0 cm,
preferably below 2.0 cm, more preferably below 1.0 cm. If the
screening is performed in the presence of non-aqueous solvent, this
helps breaking down the larger (bitumen-containing) lumps and
dissolving the bitumen.
[0025] In step (d), the first oversized material is contacted with
a solvent thereby obtaining a second solvent-diluted oil sand
slurry. Preferably, the solvent in step (d) comprises a non-aqueous
solvent. It is even more preferred that the solvent as used in
steps (b) and (d) is the same.
[0026] In step (e), the second solvent-diluted oil sand slurry is
screened, thereby obtaining a second oversized material and a
second undersized material. If desired, solvent may be removed from
the second oversized material thereby obtaining solvent-depleted
oversized material (the "rejects"). Although the removal of solvent
may be performed in various ways, it usually includes heating and
preferably the use of a purge gas, such as N.sub.2 or steam. The
second undersized material may be processed separately and e.g.
sent to a filter, but is typically combined with the first
undersized material as mentioned below.
[0027] In optional step (f), the first undersized material obtained
in step (c) is filtered, thereby obtaining a solids-depleted stream
and a solids-enriched stream. This filtration step is not limited
in any way. As the person skilled in the art is familiar with how
to perform such a filtration step, this is not further discussed
here in detail. According to an especially preferred embodiment,
the first undersized material obtained in step (c) is combined with
the second undersized material obtained in step (e), before being
filtered in step (f).
[0028] In optional step (g), solvent is removed from the
solids-depleted stream obtained in step (f) thereby obtaining a
bitumen-enriched stream. This bitumen-enriched stream may be sent
to a refinery or the like for further processing. As the person
skilled in the art is familiar with how to remove the solvent and
process the bitumen-enriched stream, this is not further discussed
here in detail.
[0029] In a further aspect the present invention provides a an
apparatus for performing the method according to the present
invention, at least comprising: [0030] a housing containing a first
section, a second section, a third section and a fourth section;
[0031] the first section having a first inlet for oil sand, a
second inlet for a solvent and an outlet for a first
solvent-diluted oil sand slurry; [0032] the second section having
an inlet for the first solvent-diluted oil sand slurry, a screen
allowing a first undersized material to pass and an outlet for a
first oversized material; and [0033] the third section having a
first inlet for the first oversized material, a second inlet for a
solvent and an outlet for a second solvent-diluted oil sand slurry;
[0034] the fourth section having an inlet for the second
solvent-diluted oil sand slurry, a screen allowing a second
undersized material to pass and an outlet for a second oversized
material;
[0035] wherein the first section, the second section, the third
section and the fourth section can rotate (as a single rotating
device) during use around a common rotation axis.
[0036] An advantage of the apparatus according to the present
invention is that the oil sand stream can be handled in a
surprisingly simple and elegant manner by providing a two-stage
mixing and screening operation in a single rotating drum.
[0037] The housing and first, second, third and fourth sections as
used in the apparatus according to the present invention are not
limited in any way. There may be more sections present than the
first, second, third and fourth sections (thereby creating further
contacting and screening areas). The housing typically surrounds
the first, second, third and fourth (and optional further) sections
and ensures that no undesired leakage of vapours to the environment
occurs; this is of particular relevance if a non-aqueous solvent is
used in the first and/or third sections. The housing may be formed
by the outer walls of the first, second, third and fourth sections
and hence does not need to be a separate element. The housing does
not necessarily (but preferably will) co-rotate during use with the
first, second, third and fourth sections. Preferably, the first
inlet of the first section, the inlet of the second section, the
first inlet of the third section and the inlet of the fourth
section are axial inlets; also it is preferred that the outlet of
the first section, the outlet of the second section, the outlet of
the third section and the outlet of the fourth section are axial
outlets. It goes without saying that further inlets and outlets may
be present (which may be axial or not).
[0038] The screens of the second and fourth (and any further)
sections may be partly integrated with the housing of the
respective sections, for example through a discharge grate which
may form part of the (typically vertical) wall near the outlet of
the respective section. As discharge grates are known in the art,
these are not further discussed here.
[0039] During use of the apparatus according to the present
invention, in the first section, oil sand is contacted with
solvent, preferably a non-aqueous solvent (and typically, if the
solvent is recycled from a downstream point of the process with
some dissolved bitumen as well) thereby obtaining a first
solvent-diluted oil sand slurry. In the second section, the first
solvent-diluted oil sand slurry is screened to allow a first
undersized material to pass; a first oversized material is
transferred to the third section. In the third section the first
oversized material is contacted with solvent thereby obtaining a
second solvent-diluted oil sand slurry. The second solvent-diluted
oil sand slurry is transferred to the fourth section and screened
therein, thereby obtaining a second oversized material and a second
undersized material. Whilst the oil sand is passing through the
first, second, third and fourth sections, these sections rotate
around a common rotation axis (i.e. as a single rotating drum).
[0040] Solvent is typically removed from the second oversized
material thereby obtaining solvent-depleted oversized material;
this solvent-depleted oversized material ("rejects") is typically
discharged for disposal after the solvent has been removed. Care is
taken that substantially no solvent vapour escapes from the
contained processing environment in the housing and hence also no
solvent vapour escapes with the solvent-depleted oversized
material.
[0041] The first and second undersized materials are typically
further processed. Preferably, the first and second undersized
materials are sent to a filter as mentioned above.
[0042] The first section, the second section, the third section and
the fourth section can rotate during use around a common rotation
axis. Typically, the first, second, third and fourth sections (and
preferably the housing as well) can co-rotate around the common
rotation axis as one single rotation assembly (i.e. in the same
direction and at the same speed).
[0043] The progression of the oil sand, slurry and other solids
containing streams through the apparatus may be aided by inclining
the first, second, third and fourth sections a few degrees from
horizontal (wherein the first section is at a higher point than the
second section, the second section at a higher point than the third
section and the third section at a higher point than the fourth
section), e.g. as done in a calcining kiln. In addition or
alternatively, lifters and/or flutes may be placed in such a way to
mechanically aid the progression of the solid containing streams or
retain it in one area for a longer time. The use of lifters also
aids in the agitation and contact of bitumen and solvent in the
first section and hence accelerates the bitumen dissolution
process, although agitation should not be so great as to break up
significant clay lumps which can hinder downstream processing.
Balls or rods may be present in the first section and/or third
section to promote the disintegration of relatively big
bitumen-containing lumps.
[0044] Preferably, the screen of the second section and the housing
define an annular pathway arranged around the screen for removing
the first undersized material passed through the screen. As
mentioned above, the housing may be formed by the outer walls of
the first, second, third and fourth sections and does not need to
be a separate element. In the case wherein the screen of the second
section and the housing define an annular pathway arranged around
the screen, the outer wall of the second section and the housing
may coincide. Preferably, the annular pathway at least partially
surrounds the third section; in this case the wall of the housing
does not coincide with the wall of the third section but is a
separate element.
[0045] It is also preferred that--similar to the screen of the
second section--the screen of the fourth section and the housing
define an annular pathway arranged around the screen for removing
the second undersized material passed through the screen.
Preferably, both an annular pathway around the screen of the second
section and around the screen of the fourth section are present,
both pathways being connected, preferably aligned.
[0046] Further it is preferred that the annular pathway (either
around the screen of the second section, around the screen of the
fourth section or both) is fluidly connected to an inlet of a
filtration unit. Preferably, the undersized material removed via
the annular pathway is thickened (i.e. made denser) prior to
feeding to the filtration unit. To that end, the apparatus
preferably comprises a thickener between the annular pathway and
the inlet of the filtration unit, typically in the form of a
hydrocyclone or the like.
[0047] Preferably, the apparatus comprises a threshold between the
first section and second section. Similarly, it is preferred that
the apparatus comprises a threshold between the third section and
fourth section. Such threshold(s) may be created in various manners
and allow that the residence time in the first and third section(s)
is increased. One example of such a threshold would be the use of
an inward facing ring between the respective sections. Preferably a
threshold is created by having a reduced diameter for the second
(and/or fourth) section (where screening takes place) relative to
the preceding first (and/or third section). The person skilled in
the art will readily understand that further thresholds may be
present in case the apparatus comprises further sections for
contacting and screening; in such case the threshold(s) is (are)
preferably located at the inlet of a further screening section.
[0048] According to a preferred embodiment of the apparatus
according to the present invention, the apparatus comprises an
inner screen which is concentrically arranged with respect to the
screen of the second section and the screen of the fourth section.
In the second section and the fourth section the inner screen is
surrounded (at a predetermined distance) by the respective screens.
Such an inner screen helps to keep the larger rocks away from the
more fragile screens of the second and fourth section,
respectively. Preferably, the inner screen connects the outlet of
the first section to the outlet of the fourth section; in the
latter case, the inner screen runs through the second, third and
fourth section. In case the apparatus comprises more than two
screening sections (such as the second and fourth sections), the
inner screen may be surrounded by the screen of such further
screening sections.
[0049] The apparatus may comprise one or more outlets for solvent
vapour. The outlet for solvent vapour may be located at various
places (such as in any of the first to fourth section), but is
preferably located in the fourth section. Preferably, the outlet
for solvent vapour is connected to an inlet of a solvent recovery
unit. Furthermore, the apparatus according to the present invention
typically comprises an inlet for a purge gas, such as N.sub.2 or
steam. Preferably, the outlet for solvent vapour as mentioned above
also functions as an outlet for the purge gas.
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] Hereinafter the invention will be further illustrated by the
following non-limiting drawings. Herein shows:
[0051] FIG. 1 schematically a first non-limiting embodiment of an
apparatus in accordance with the present invention; FIG. 2 a
cross-section through the apparatus of FIG. 1 at line B-B' to
illustrate the annular pathway 7A;
[0052] FIGS. 3-6 schematically a part of further non-limiting
embodiments of an apparatus in accordance with the present
invention; and
[0053] FIG. 7 a cross-section through the apparatus of FIG. 6 at
line C-C' to illustrate the relative position of the annular inner
screen 23.
DETAILED DESCRIPTION OF THE DRAWINGS
[0054] For the purpose of this description, a single reference
number will be assigned to a line as well as a stream carried in
that line.
[0055] FIG. 1 schematically shows a simplified apparatus according
to the present invention for removing rejects from an oil sand
stream, from which subsequently bitumen is to be extracted. The
apparatus is generally referred to with reference numeral 1. The
apparatus 1 comprises a cylindrical housing 2 that rotates during
use around the axis A-A'. Housing 2 comprises a first section 3
(for mixing/contacting), a second section 4 (for screening), a
third section 5 (for mixing/contacting) and a fourth section 6 (for
screening) contained therein. Further shown is a filtration unit 8,
a VRU (vapour recovery unit) 9, a solvent source 11, a deoxygenator
12, rotating seals 13, a pumpbox 14, a conveyor belt 15, a
clarifier 16, a drier 17 and a hydrocyclone 18.
[0056] The first section 3 has a first (axial) inlet 31 for oil
sand, a second inlet 32 for solvent (which may feed into the
second, third and fourth sections as well) and an (axial) outlet 33
for a first solvent-diluted oil sand slurry. Also, the first
section 3 has tapering guide plates 34 for guiding the
solvent-diluted oil sand slurry towards the (axial) outlet 33/inlet
41.
[0057] The second section 4 has an (axial) inlet 41 for the first
solvent-diluted oil sand slurry (which inlet 41 corresponds to the
outlet 33 of the first section 3), a(n annular) screen 42 allowing
a first undersized material to pass and an (axial) outlet 43 for a
first oversized material.
[0058] The third section 5 has a first (axial) inlet 51 for the
first oversized material (which first inlet 51 corresponds to the
outlet 43 of the second section 4), a second inlet 52 for a solvent
and an (axial) outlet 53 for a second solvent-depleted oil sand
slurry.
[0059] The fourth section 6 has an (axial) inlet 61 for the second
solvent-diluted oil sand slurry, a(n annular) screen 62 allowing a
second undersized material to pass and an outlet 63 for a second
oversized material. Also, the fourth section 6 has an inlet 64 for
a purge gas, such as N.sub.2 or steam. The purge gas inlet 64 may
also be located in one of the other sections; also, there may be
two or more of such purge inlets. The fourth section 6 may further
comprise an outlet 65 for solvent vapour and/or purge gas. In the
embodiment of FIG. 1, outlet 65 is connected to an inlet of a
solvent recovery unit 9.
[0060] In the embodiment of FIG. 1, the screen 42 of the second
section 4 and the housing 2 (which in the embodiment of FIG. 1
coincides with the outer wall of the second section 4) define an
annular pathway 7A arranged around the screen 42 (and in the
embodiment of FIG. 1 also around third section 5) for removing the
first undersized material passed through the screen 42. Similarly,
the screen 62 of the fourth section 6 and the housing 2 define an
annular pathway 7B arranged around the screen 62 for removing the
second undersized material passed through the screen 62. The
annular pathways 7A and 7B are connected and (in the embodiment of
FIG. 1) aligned. The annular pathways 7A and 7B are fluidly
connected to the inlet 81 of the filtration unit 8, via the pumpbox
14 and the hydrocyclone 18.
[0061] The first section 3, the second section 4, the third section
5 and the fourth section 6 can co-rotate during use as one single
rotation assembly (preferably also including the housing 2) around
the common rotation axis A-A'. Typically, the axis A-A' is at a
slight angle (up to 3.degree.) with the horizontal to assist the
(slightly downwards) flow from the first section 3 into the second
section 4 and then into the third section 5 and fourth section 6.
For the sake of simplicity no driver has been shown for achieving
the rotation of the first section 3, the second section 4, the
third section 5 and the fourth section 6; the person skilled in the
art will readily understand that this driver is not limited in any
way. Preferably, (and as shown in FIGS. 3-5) there are thresholds
(e.g. by using reduced diameters for the second and fourth
sections) between the first section 3 and second section 4 and
between the third section 5 and fourth section 6 to increase the
residence time in the first section 3 and the third section 5 for
enhanced mixing.
[0062] As shown in the embodiment of FIG. 1, the housing 2 is
preceded by a deoxygenation unit 12.
[0063] During use of the apparatus 1 as embodied in FIG. 1, a
crushed oil sand stream 10 is sent to a de-oxygenation unit 12 to
remove oxygen. Subsequently, the deoxygenated oil sand is passed as
stream 20 to and fed into the first section 3 (for mixing) for
contacting the oil sand stream with a solvent such as pentane
thereby obtaining a first solvent-diluted oil sand slurry. The
solvent may be obtained as stream 80 from solvent source 11 (fed
via inlet 32), and/or recycled from a point downstream in the
process (e.g. stream 100; although in FIG. 1, stream 100 is fed
just upstream of the first section 3). Balls or rods may be added
to the first section 3 (and/or third section 5) to promote the
disintegration of relatively big bitumen-containing lumps.
[0064] The first solvent-diluted oil sand slurry is screened in the
second section 4 (for screening) using the screen 42, thereby
obtaining a first oversized material and a first undersized
material. The first oversized material is passed to the third
section 5 (for mixing) to be contacted with solvent (fed via inlet
52), thereby obtaining a second solvent-diluted oil sand slurry.
The second solvent-diluted oil sand slurry is screened in fourth
section 6 (for screening), thereby obtaining a second oversized
material and a second undersized material.
[0065] The second oversized material (or "rejects") 70 is removed
via e.g. a conveyor belt 15 (alternatively, lifters or the like may
be used instead of a conveyor belt). The rejects 70 can be used
e.g. for land reclamation or simply disposed, possibly after
further solvent removal.
[0066] The first undersized material as obtained in the second
section 4 and the second undersized material as obtained in the
fourth section 6 flow through the annular pathway 7A defined by the
screen 42 and the housing 2 and the pathway 7B as defined by the
screen 62 and the housing 2 to the pumpbox 14. Then, it is pumped
as stream 30 to hydrocyclone 18 for thickening. The thickened
undersized material is subsequently sent as stream 35 to the inlet
81 of the filtration unit 8 and filtered thereby obtaining a
solids-depleted stream 40 and a solids-enriched stream 50 (if
desired, using solvent stream 90 from the solvent source 11).
Solvent is removed from the solids-enriched stream 50 in drier 17
thereby obtaining a dried solids-enriched stream 60 which is often
referred to as "tailings". The solids-depleted stream 40 is
relatively bitumen-rich and is further processed (as stream 40A) to
recover the bitumen which may be further upgraded in a refinery
(not shown) or the like; usually, the solids-depleted stream 40A is
first sent to a clarifier 16. As shown in FIG. 1 part 40B of the
solids-depleted stream 40 may be reused in the process, e.g. as
solvent to be used for the contacting in the first section 3 and/or
third section 5. Also, solids-depleted stream 100 recovered from
stream 30 in hydrocyclone 18 may be combined with the deoxygenated
oil sand stream 20.
[0067] FIG. 2 shows a cross-section through the apparatus 1 of FIG.
1 at line B-B' (through second section 4) to further illustrate the
annular pathway 7A defined by the screen 42 and the housing 2
(coinciding with the outer wall of the second section 4).
[0068] FIGS. 3-6 schematically show a part of further non-limiting
embodiments of an apparatus 1 in accordance with the present
invention. Not all lines and components have been shown in FIGS.
3-6. The embodiments of FIGS. 3-6 all have thresholds between the
first section 3 and second section 4 and between the third section
5 and fourth section 6 (and between the fifth section 21 and sixth
section 22) to increase the residence time in the first section 3
and the third section 5 (and fifth section 21) for enhanced mixing.
The threshold is created by a reduced diameter for the second
section 4 and fourth section 6 (and sixth section 22), when
compared with the diameter for the first section 3 and third
section 5 (and fifth section 21), respectively.
[0069] Further, FIGS. 3-4 show that the undersized material from
the screens of sections 4 and 6 may be removed in other ways than
through the annular pathway 7A,7B as shown in FIG. 1.
[0070] In the embodiment of FIG. 5, the apparatus comprises a fifth
section 21 and sixth section 22; hence, the embodiment of FIG. 5
has 3 stages of contacting/mixing and screening. The screen 25 of
the sixth section 6 and the housing 2 define an annular pathway 7C
arranged around the screen 25 for removing the second undersized
material passed through the screen 25. Annular pathway 7C is
aligned with annular pathways 7A and 7B.
[0071] In the embodiment of FIG. 6 (again comprising a fifth
section 21 and a sixth section 22), an additional (annular) inner
screen 23 is included. The inner screen 23 connects the outlet 33
of the first section 3 to (the outlet 63 of the fourth section 6
and) the outlet 24 of the sixth section 22 and hence passes through
second section 4, third section 5, fourth section 6, fifth section
21 and sixth section 22. The inner screen 23 is relatively
`coarse`, i.e. allows more material to pass than the screens
42,62,25 do. Such an inner screen 23 helps to keep the larger rocks
away from the more fragile screens 42,62,25.
[0072] FIG. 7 shows a cross-section through the apparatus 1 of FIG.
6 at line C-C' (through second section 4) to further illustrate the
annular pathway 7A defined by the screen 42 and the housing 2, and
the relative position of the (annular) inner screen 23 with respect
to the screen 42. As can be seen in FIG. 7, the inner screen is
concentrically arranged with respect to screen 42 of the second
section 4 (and similarly with respect to screen 62 of the fourth
section 6 and screen 25 of the sixth section 22).
[0073] The person skilled in the art will readily understand that
many modifications may be made without departing from the scope of
the invention. Further, the person skilled in the art will readily
understand that, while the present invention in some instances may
have been illustrated making reference to a specific combination of
features and measures, many of those features and measures are
functionally independent from other features and measures given in
the respective embodiment(s) such that they can be equally or
similarly applied independently in other embodiments.
* * * * *