Note: Descriptions are shown in the official language in which they were submitted.
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HORIZONTAL-FLOW OIL SANDS SEPARATOR FOR A SOLVENT
EXTRACTION PROCESS
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the priority benefit of United States Patent
Application
62/067,279 filed October 22, 2014 entitled HORIZONTAL-FLOW OIL SANDS
SEPARATOR FOR A SOLVENT EXTRACTION PROCESS, the entirety of which is
incorporated by reference herein.
BACKGROUND
[0002] This section is intended to introduce various aspects of the art,
which may be
associated with the present disclosure. This discussion is believed to assist
in providing a
framework to facilitate a better understanding of particular aspects of the
present disclosure.
Accordingly, it should be understood that this section should be read in this
light, and not
necessarily as admissions of prior art.
[0003] Oil sands are sand deposits which in addition to sand comprise
clays, connate-
water and bitumen. Depending on the depth of the deposit, bitumen may be
recovered by
mining or in situ thermal methods. Oil sand ore in a mining and extraction
operation is
typically processed using mechanical means and chemicals addition to separate
the bitumen
from the sands. Recovering the highly viscous bitumen from the oil sand poses
numerous
challenges, particularly since large quantities of heat and water are required
to extract the
bitumen. Further, most oil sand deposits are located in remote areas (such as,
for example, in
northeastern Alberta, Canada), which can contribute to increased costs for
transportation and
processing, especially in harsh weather conditions. Because of these
challenges, obtaining a
good yield of bitumen product from the oil sands is desired in order to reduce
costs and
waste.
[0004] In conventional gravity separators, a slurry stream comprising
liquid and solid
particles is delivered to a vessel where the solid particles settle by gravity
and are removed
from the bottom of the vessel, while the clarified liquid is removed from the
top of the vessel.
In most processes, the solid particles are distributed in size, where the
large particles settle
more quickly and the small particles settle more slowly. Particles that have
settling velocities
smaller than the upward flux (superficial velocity) of the liquid may not
settle at all, but may
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instead be carried over with the clarified liquid. Conventional separators
generally achieve
their optimum separation efficiency by having a uniform upward velocity
distribution as this
determines the theoretical limit of the maximum particle size that can be
carried over.
Increasing the vessel size, for example, decreases the upward velocity and
thereby reduces
the size of the largest particles that carry-over, thereby increasing the
fraction of particles that
report to the underflow.
[0005] The water-based extraction process (WBE) is a commonly used
process to extract
bitumen from mined oil sands. In another technique, a non-water-based
extraction process
can be used to treat the strip or surface mined oil sands. The non-water-based
extraction
process may interchangeably be referred to as a solvent based extraction
process or an oil
sands solvent extraction process. The commercial application of a solvent
based extraction
process has, for various reasons, eluded the oil sands industry. A major
challenge associated
with the solvent based extraction process is the tendency of fine particles
within the oil sands
to hamper the separation of solids from the heavy oil extracted. The heavy oil
extracted may
interchangeably be referred to as bitumen extract. Fine particles may
interchangeably be
referred to as a fine solids stream or fines.
[0006] One proposed way to handle the challenge of fine particles is
described in
Canadian Patent No. 1,169,002 (Karnofsky). Karnofsky describes a process
wherein an oil
sands slurry is separated into a coarse solids stream and a fine solids stream
by gravity
separation. Bitumen extract is removed from the coarse solids stream by using
a series of
percolating beds. Bitumen extract is removed from the fines solids stream by
using a
complicated system of clarifiers, thickeners, and filters. Despite the process
described in
Karnofsky, solid-liquid separation of the fines solids stream remains a
challenge.
[0007] Another proposed way to handle the challenge of fine particles is
by using a solid
agglomeration process. The solid agglomeration process was coined Solvent
Extraction
Spherical Agglomeration (SESA). A description of the SESA process can be found
in Sparks
et al., Fuel 1992(71); pp 1349-1353. Previously described methodologies for
SESA have not
been commercially adopted. In general, the SESA process involves mixing oil
sands with a
hydrocarbon solvent to form an oil sands slurry, adding an aqueous bridging
liquid to the oil
sands slurry to form a mixture, agitating the mixture in a slow and controlled
manner to
nucleate particles, and continuing such agitation so as to permit these
nucleated particles to
form larger multi-particle spherical agglomerates for removal. The aqueous
bridging liquid
may be water or an aqueous solution since the solids of oil sands are mostly
hydrophilic and
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water is immiscible to hydrocarbon solvents. The aqueous bridging liquid
preferentially wets
the solids. With the right amount of the aqueous bridging liquid and suitable
agitation of the
slurry, the aqueous bridging liquid displaces the suspension liquid on the
surface of the
solids. As a result of interfacial forces among three phases (i.e. the aqueous
bridging liquid,
the suspension liquid, and the solids), fine particles within the solids
consolidate into larger,
compact agglomerates that are more readily separated from the suspension
liquid.
[0008] U.S. Patent No. 4,719,008 (Sparks) describes a process that
applies SESA using a
micro-agglomerate procedure. In Sparks, the SESA process occurs within a
slowly rotating
horizontal vessel. The conditions of the slowly rotating horizontal vessel are
that which favor
the formation of large agglomerates; however, a light milling action is used
to continuously
break down the agglomerates. The micro-agglomerates are formed by obtaining an
eventual
equilibrium between cohesive and destructive forces. Since rapid agglomeration
and
agglomerates of large size can lead to bitumen recovery losses owing to
entrapment of
bitumen extract within the agglomerated solids, the level of bridging liquid
is kept to as low
as possible commensurate with achieving economically viable solid-liquid
separations.
[0009] With the formation of micro-agglomerates, the process of solid-
liquid separation
using common separation devices is easier compared to a situation where fine
particles are
not micro-agglomerated. Applicable separation devices include at least one of
gravity
separators, centrifuges, cyclonic separation devices, screens and filters.
Although the
separation devices have been shown to be effective in separating agglomerates
from liquids,
they have disadvantages that may limit their application in an oil sands
solvent extraction
process. For example, gravity separators, such as clarifiers and incline plate
separators, can
result in a bitumen extract of low solids content; the underflow from the
gravity separators is
expected to have a substantial amount of bitumen extract entrained within the
underflow.
Because of this bitumen entrainment in the underflow, a significant amount of
wash solvent
and many wash stages is needed to separate the substantial amount of bitumen
extract ¨
interchangeably referred to as residual bitumen ¨ from the solids. Cyclonic
separation
devices, such as hydrocyclones, are compact and allow for rapid separation of
solids from
liquids. However, it is difficult to use cyclonic separation devices to
clarify the bitumen
extract and concentrate the solids stream to, say, greater than 50 wt.%
solids. In solid-liquid
separation processes, paste thickeners, centrifuges or filters are known to
produce solid
slurries of greater than 50 wt.%. The paste thickeners, centrifuges or filters
have moving
parts that may challenge their reliability in the high solids content and
hydrocarbon
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environment of the solvent extraction process.
[0010] Consequently, a need exists for an efficient oil sands separator
in an oil sands
solvent extraction process that reduces the space requirements at the site.
Further, a need
exists for an efficient oil sands separator for an oil sands solvent
extraction process that
reduces the difficulties and/or expenses associated with manufacture and/or
transportation to
remote sites.
[0011] Bitumen product cleaning generally refers to another stage within
the oil sands
process wherein solid separation is required. In a bitumen product cleaning
process, bitumen
extracted from the ore yet still containing varying amounts of water and
solids is subjected to
a deasphalting process, which forms asphaltene-rich aggregates that can be
removed with
residual solids and water via gravity settling. Conventional gravity settling
may generally
refer to techniques for separating a feed containing immiscible phases of
different densities,
e.g., settling of a feed in a vessel to obtain a heavier phase zone in the
vicinity of the base and
a lighter phase zone above an interface with the heavier phase zone. U.S.
patent publication
number 2012/014,653, titled "Apparatus and Method for Separating a Feed
Material
Containing Immiscible Phases of Different Densities," contains a
representative gravity
settling approach.
SUMMARY
[0012] One embodiment includes a system for recovering hydrocarbons from
a
bituminous feed in an oil sands solvent extraction process, comprising a
vessel comprising a
feed inlet on a proximate end of the vessel, a feed outlet on a distal end of
the vessel, a
bitumen outlet, and a plurality of hoppers, wherein each hopper comprises a
tailing outlet.
[0013] Another embodiment includes a method for recovering hydrocarbons
in an oil
sands solvent extraction process, comprising passing a bituminous feed through
an inlet of a
vessel, passing the bituminous feed across a plurality of hoppers disposed on
a lower end of
the vessel, separating the bituminous feed into a stream comprising bitumen
and a stream
comprising tailings, passing the stream comprising bitumen from the vessel,
and passing the
stream comprising tailings from the vessel.
[0014] Still another embodiment includes a system for separating a
bituminous feed in an
oil sands solvent extraction process, comprising a vessel, an inlet device
coupled to a vessel
and configured to receive the bituminous feed, an outlet device coupled the
vessel and
configured to discharge a tailings feed, a plurality of bitumen outlets
disposed on the vessel, a
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plurality of hoppers disposed on a lower end of the vessel, wherein each
hopper comprises a
tailing outlet, and a secondary extraction vessel operatively coupled to the
outlet device so as
to pass bitumen extracted in the secondary extraction vessel to the inlet
device in a counter-
current extraction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The advantages of the present techniques are better understood by
referring to the
following detailed description and the attached drawings, in which:
[0016] FIG. 1 is a schematic diagram of a separator system for separating
a bituminous
feed in an oil sands solvent extraction process.
[0017] FIG. 2 is a cross section of a horizontal-flow separator system for
recovering
hydrocarbons from a bituminous feed in an oil sands solvent extraction
process.
[0018] FIG. 3A is an inlet side view cross sectional diagram of a system
for recovering
hydrocarbons from a bituminous feed in an oil sands solvent extraction
process.
[0019] FIG. 3B is a perspective view of the system for recovering
hydrocarbons from a
bituminous feed in an oil sands solvent extraction process.
[0020] FIG. 4 is a block diagram describing a process for recovering
hydrocarbons from
a bituminous feed in an oil sands solvent extraction process.
[0021] FIG. 5 is a block diagram describing a continued process for
recovering
hydrocarbons from a bituminous feed in an oil sands solvent extraction
process.
[0022] FIG. 6 is an embodiment of system for recovering hydrocarbons from a
bituminous feed in an oil sands solvent extraction process.
DETAILED DESCRIPTION
[0023] In the following detailed description section, specific
embodiments of the present
techniques are described. However, to the extent that the following
description is specific to
a particular embodiment or a particular use of the present techniques, this is
intended to be
for exemplary purposes only and simply provides a description of the exemplary
embodiments. Accordingly, the techniques are not limited to the specific
embodiments
described herein, but rather, include all alternatives, modifications, and
equivalents falling
within the true spirit and scope of the appended claims.
[0024] Disclosed herein is a horizontal-flow separator for separating
bitumen/water/solids
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stream(s) in oil sands operations. Many configurations are possible, some
including small
diameter fingers to accomplish polishing of the solvent/bitumen prior to
further processing
and commercialization. For example, the primary separator vessel may be the
first stage
separator in a process, with the smaller fingers serving as the second stage
separator.
Alternately, both stages could simultaneously accomplish one step of
separation in the overall
process. Some embodiments place feeds or draws between these two parts of a
separation
system. Conical section(s) in the first and/or second stage separators may
have different base
angles and/or sizes depending on the various physical properties and/or
characteristics of the
liquids and solids being processed.
[0025] Horizontal-flow separators may be inherently better at remove
smaller particles
often found in oil sands tailings. Additionally, horizontal-flow separators
may allow
designers an additional degree of freedom in sizing the separator(s). Owing to
Stokes' Law,
vertical-flow separators depend on the upflow velocity to determine the
theoretical particle
cut-size obtainable with the separator. Both diameter (superficial fluid
velocity) and length
(residence time) can be adjusted for horizontal-flow separators to meet
product stream
specifications based upon Stokes' Law settling. However, disclosed horizontal-
flow designs
allow designers additional degrees-of-freedom in configuring the separator(s).
As the
disclosed separators include generally smaller diameter vessels (or even pipe
size fingers), it
is likely to facilitate manufacture and transport to remote sites, resulting
in capital savings
over the current separator technology. Labor costs to erect the separator
should also be
reduced in view of the above.
[0026] At the outset, for ease of reference, certain terms used in this
application and their
meanings as used in this context are set forth. To the extent a term used
herein is not defined
herein, it should be given the broadest definition persons in the pertinent
art have given that
term as reflected in at least one printed publication or issued patent.
Further, the present
techniques are not limited by the usage of the terms shown herein, as all
equivalents,
synonyms, new developments, and terms or techniques that serve the same or a
similar
purpose are considered to be within the scope of the present claims.
[0027] As used herein, the term "Bitumen" is a naturally occurring heavy
oil material.
Generally, it is the hydrocarbon component found in oil sands. Bitumen can
vary in
composition depending upon the degree of loss of more volatile components. It
can vary
from a very viscous, tar-like, semi-solid material to solid forms. The
hydrocarbon types
found in bitumen can include aliphatics, aromatics, resins, and asphaltenes. A
typical
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bitumen might be composed of:
19 weight (wt.) % aliphatics (which can range from 5 wt. % - 30 wt. %, or
higher);
19 wt. % asphaltenes (which can range from 5 wt. % - 30 wt. %, or higher);
30 wt. % aromatics (which can range from 15 wt. % - 50 wt. %, or higher);
32 wt. % resins (which can range from 15 wt. % - 50 wt. %, or higher); and
some amount of sulfur (which can range in excess of 7 wt. %).
In addition, bitumen can contain some water and nitrogen compounds ranging
from less than
0.4 wt. % to in excess of 0.7 wt. %. The percentage of the hydrocarbon found
in bitumen can
vary. The term "heavy oil" includes bitumen as well as lighter materials that
may be found in
a sand or carbonate reservoir.
[0028] As used herein, the term "bituminous feed" refers to a stream
derived from oil
sands that requires downstream processing in order to realize valuable bitumen
products or
fractions. The bituminous feed is one that comprises bitumen along with
undesirable
components. Such a bituminous feed may be derived directly from oil sands, and
may be, for
example, raw oil sands ore. Further, the bituminous feed may be a feed that
has already
realized some initial processing, e.g., non-aqueous extraction (NAE)
processing, solvent
extraction processing, etc., but nevertheless requires further processing.
Also, recycled
streams that comprise bitumen in combination with other components for removal
as
described herein can be included in the bituminous feed. A bituminous feed
need not be
derived directly from oil sands, but may arise from other processes. For
example, a waste
product from other processes which comprises bitumen that would otherwise not
have been
recovered, may be used as a bituminous feed. Such a bituminous feed may be
also derived
directly from oil shale oil, bearing diatomite or oil saturated sandstones.
[0029] As used herein, the phrase "fine particles" means those solids
having a size of less
than 44 microns (nm), that is, material that passes through a 325 mesh (44
micron). The
aforementioned range includes any number within the range.
[0030] As used herein, the phrase "coarse particles" means those solids
having a size of
greater than 44 microns (nm). The aforementioned range includes any number
within the
range.
[0031] As used herein, the phrase "Heavy oil" includes oils which are
classified by the
American Petroleum Institute ("API"), as heavy oils, extra heavy oils, or
bitumens. The term
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"heavy oil" includes bitumen. Heavy oil may have a viscosity of about 1,000
centipoise (cP)
or more, 10,000 cP or more, 100,000 cP or more, or 1,000,000 cP or more. In
general, a
heavy oil has an API gravity between 22.3 API (density of 920 kilograms per
meter cubed
(kg/m3) or 0.920 grams per centimeter cubed (g/cm3)) and 10.0 API (density of
1,000 kg/m3
or 1 g/cm3). An extra heavy oil, in general, has an API gravity of less than
10.0 API
(density greater than 1,000 kg/m3 or 1 g/cm3). For example, a source of heavy
oil includes oil
sand or bituminous sand, which is a combination of clay, sand, water and
bitumen. The
recovery of heavy oils is based on the viscosity decrease of fluids with
increasing temperature
or solvent concentration. Once the viscosity is reduced, the mobilization of
fluid by steam,
hot water flooding, or gravity is possible. The reduced viscosity makes the
drainage quicker
and therefore directly contributes to the recovery rate.
[0032] As used herein, the terms "bitumen", "bitumens", and "bituminous
feed" are used
interchangeably.
[0033] As used herein, the term "solvent" can refer to either a single
chemical
component, or a mixture of chemical components, to promote the dissolution of
other
chemical compounds.
[0034] As used herein, the terms "solvent extracted bitumen" and "solvent
diluted
bitumen" refer to bitumen that is dissolved into another hydrocarbon. This
other hydrocarbon
could refer to a solvent used to extract the bitumen to facilitate removal
from the other ore
components or alternatively could refer to a solvent that dissolves only a
portion of the
bitumen molecules.
[0035] As used herein, the term "hopper" means a container with a narrow
opening at
bottom. This definition is intended to encompass frustum-shaped hoppers, e.g.,
pyramidal
frustum, conical frustum, square frustum, pentagonal frustum, etc., as well as
various
prismatoids and other slant geometries that may be suitably be employed by
those of skill in
the art to practice the techniques described herein.
[0036] As used herein, the term "hydrocarbon" means an organic compound
that
primarily includes the elements of hydrogen and carbon, although nitrogen,
sulfur, oxygen,
metals, or any number of other elements may be present in small amounts.
Hydrocarbons
generally refer to components found in heavy oil or in oil sands. However, the
techniques
described are not limited to heavy oils but may also be used with any number
of other
reservoirs to improve gravity drainage of liquids. Hydrocarbon compounds may
be aliphatic
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or aromatic, and may be straight chained, branched, or partially or fully
cyclic.
[0037] As used herein, the term "macro-agglomeration" means the
consolidation of both
fine particles and coarse particles that make up the oil sands. Macro-
agglomerates may have
a mean diameter of 2 millimeters (mm) or greater.
[0038] As used herein, the term "micro-agglomeration" means the
consolidation of fine
particles that make up the oil sands. Micro-agglomerates may have a mean
diameter of less
than 2 millimeters (mm).
[0039] As used herein, the term "tailings" means an underflow material
remaining in a
mixture after bitumen is separated from an oil sands or a bituminous feed.
Tailings generally
comprise the refuse material comprising fine and/or coarse particles of sand
and/or clay,
traces of bitumen, asphaltenes, etc. remaining after the bitumen has been
extracted from the
bituminous feed.
[0040] As used herein, the phrase "product cleaning" refers to a process
wherein bitumen
is subjected to a process to reduce impurities (including, but not limited to,
water and solids)
to levels that allow for direct marketing to refineries or to match feed
requirements for other
conversion technologies focused on generating a synthetic crude oil or to meet
pipeline
product specifications.
[0041] As used herein, the phrases "solvent-based recovery process" or
"solvent
extraction process" include any type of hydrocarbon recovery process that uses
a solvent, at
least in part, to enhance the recovery, for example, by diluting or lowering a
viscosity of the
hydrocarbon. Solvent-based recovery processes may be used in combination with
other
recovery processes, such as, for example, thermal recovery processes. As used
herein, the
terms "a" and "an," mean one or more when applied to any feature in
embodiments of the
present inventions described in the specification and claims. The use of "a"
and "an" does
not limit the meaning to a single feature unless such a limit is specifically
stated.
[0042] As used herein, the term "about" means 10% of the subsequent
number, unless
otherwise stated.
[0043] As used herein, the terms "approximate," "approximately,"
"substantial," and
"substantially," mean a relative amount of a material or characteristic that
is sufficient to
provide the intended effect. The exact degree of deviation allowable in some
cases may
depend on the specific context. It should be understood by those of skill in
the art who
review this disclosure that these terms are intended to allow a description of
certain features
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described and claimed without restricting the scope of these features to the
precise numeral
ranges provided. Accordingly, these terms should be interpreted as indicating
that
insubstantial or inconsequential modifications or alterations of the subject
matter described
and are considered to be within the scope of the disclosure.
[0044] As used herein, the definite article "the" preceding singular or
plural nouns or
noun phrases denotes a particular specified feature or particular specified
features and may
have a singular or plural connotation depending upon the context in which it
is used.
[0045] FIG. 1 is a schematic diagram of a conventional separator system
100 for
separating a bituminous feed in an oil sands solvent extraction process. The
separator system
100 includes a deep cone settler 102 is depicted for receiving agglomerated
slurry 104 from
an agglomerator (not depicted). The deep cone settler 102 permits settling of
agglomerated
solids to the lower region 106, while a low solids bitumen extract 108 can be
drawn off as
overflow. A pump 110 is used to convey the overflow to further cleaning or
solvent removal
in a solvent recovery unit. A vent gas 112a and 112b is provided to and
removed from the
deep cone settler 102 to provide a low oxygen environment within the deep cone
settler 102.
One or more pumps 114 may be used to pump agglomerates 116 to a counter-
current washer
118, e.g., a belt filter or a rotary pan filter, for effecting recovery of
residual bitumen from
agglomerates.
[0046] FIG. 2 is a cross section of a horizontal-flow separator system
200 for recovering
hydrocarbons from a bituminous feed in an oil sands solvent extraction
process. The system
200 includes a vessel 202 having a feed inlet 204 on a proximate end 206 of
the vessel 202
and a feed outlet 208 on a distal end 210 of the vessel 202. The vessel 202
also has a
plurality of bitumen outlets 212 on an upper end 214 of the vessel 202 and
hoppers 216
having solvent and/or tailing outlets 218 on a lower end 221 of the vessel
202. The vessel
202 optionally houses a plurality of internal flow path obstructions or
baffles 220, e.g.,
perforated baffles, disposed across the internal surface of the vessel 202.
The bitumen outlets
212 optionally comprise outlet baffles 222, e.g., perforated baffles. While
shown at
approximately the midline of the top of the vessel 202, those of skill in the
art will recognize
that the bitumen outlets 212 may alternately or additionally be located
elsewhere on the upper
end 214 of the vessel 202, e.g., on or towards the distal end 210, within the
scope of this
disclosure. Similarly, while shown at approximately the centerline of the
vessel 202, those of
skill in the art will appreciate that a plurality of suitable locations exist
for placement of the
feed inlet 204 and the feed outlet 208, e.g., on the upper end 214, the lower
end 221, or a
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side, upper, or lower wall of the vessel 202 at the proximate end 206 or
distal end 210 of the
vessel 202. Such alternate placement may be based on a variety of
considerations, e.g.,
obtaining a desired flowpath into and/or out of the vessel 202, structural
limitations external
to the vessel 202, etc. The vessel 202 may optionally include one or more
injection inlets
(not depicted) for injecting water and/or solvent.
[0047] In operation, a bituminous feed may enter the vessel 202 through
the feed inlet
204. The feed may flow horizontally across the vessel 202 and the hoppers 216
to the feed
outlet 208. As feed flows across the hoppers 216, the angle of the wall(s) of
each hopper 216
and the upflow (rise) created by feed incidence against the wall(s) of each
hopper 216 may
cause separation according to known particle settling principles, e.g.,
Stokes' Law settling.
This process causes bitumen to float to the top of the vessel 202 where it may
be collected via
bitumen outlets 212. In some embodiments, the size, shape, and/or narrowing
angle of the
hopper (or incidence wall angle) of the hoppers 216 are varied from one hopper
216 to
another, e.g., to obtain bulk and fine settling, to alter the rate of rise
and/or settling, etc. In
some embodiments, separation may alternatively or be additionally accomplished
through
horizontal flow settling as in traditional three-phase separators. Thus,
hoppers 216 may
function to collect high solid component streams for ease of continuous
removal (e.g.,
separation may not necessarily be created by upflow caused by impedance
against hopper
walls).
[0048] The velocity of the bituminous feed flow may be altered by a variety
of techniques
known in the art, e.g., via pressurization, preliminary feed treatment,
additional pumps, etc.,
in order to obtain certain desired separation characteristics within the
vessel 202. Alternately
or additionally, as described above, baffles 220 and/or 222 may be optionally
added at
various points to impede or direct flow. Additionally, some embodiments may
inject water
and/or solvent into the feed stream via an injection inlet disposed on the
vessel 202 in order
to alter one or more characteristics of the feed, e.g., viscosity, separation,
disaggregation, etc.
As the feed separates, water and/or tailings, may pass through the solvent
and/or tailing
outlets 218 as bitumen is collected through the bitumen outlets 212. A feed
stream
comprising substantially unseparated bituminous feed may continue through the
feed outlet
208. In some embodiments, at least a portion of the discharge through the feed
outlet 208 is
recycled through the vessel 202. In some embodiments, at least a portion of
the discharge
through the feed outlet 208 is passed to a second vessel 202 to substantially
repeat the
process.
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[0049] FIG. 3A is an inlet side view cross sectional diagram of a system
300 for
recovering hydrocarbons from a bituminous feed in a solvent extraction
process. FIG. 3B is a
perspective view of the system 300 for recovering hydrocarbons from a
bituminous feed in a
solvent extraction process. The components of the system 300 may be
substantially the same
as the corresponding components of FIG. 2 unless otherwise noted. The system
300
comprises a secondary separator 302 commonly coupled to the tailing outlets
218. Some
embodiments may attach a secondary separator 302 to less than all of the
tailing outlets 218,
and other embodiments may attach separate secondary separators 302 to one or
more of the
tailing outlets 218. The secondary separator 302 has a water and/or solvent
injection inlet
303 for injecting water and/or solvent. Those of skill in the art will
appreciate that in some
embodiments the solvent injection inlet 303 may optionally comprise a common
injection
header spanning the length of a common secondary separator 302 or a plurality
of secondary
separators 302 (in suitable embodiments) for distributing the water and/or
solvent. The
secondary separator 302 has a plurality of secondary vessels 304, also
referred to herein as
"fingers" 304, having a plurality of secondary hoppers 306 with secondary
water and/or
tailings outlets 308. While depicted with a plurality of secondary hoppers
306, alternate
embodiments may have more, fewer, or even no secondary hoppers 306. Further,
different
fingers 304 may have differing numbers of secondary hoppers 306, and may
include differing
sizes, shapes, and/or narrowing angles of any of the secondary hoppers 306.
The fingers 304
each have a hydrocarbon or bitumen outlet 310 for passing hydrocarbons
therethrough.
Although not depicted, those of skill in the art will appreciate that a
plurality of baffles may
be optionally added in the secondary separator 302 as described above with
respect to the
baffles 220 and/or 222 in the vessel 202.
[0050] In operation, the vessel 202 portion of the system 300 may
function as described
above in connection with the system 200. Namely, a bituminous feed may enter
the vessel
202 through the feed inlet 204. The feed may flow horizontally across the
vessel 202 and the
hoppers 216 to the feed outlet 208. As feed flows across the hoppers 216, the
angle of the
wall(s) of each hopper 216 and the upflow (rise) created by feed incidence
against the wall(s)
of each hopper 216 causes separation according to known particle settling
principles. This
process causes bitumen to float to the top of the vessel 202 where
hydrocarbons may be
collected via bitumen outlets 212. As the feed separates, a stream comprising
substantially
unseparated bituminous feed may continue through the feed outlet 208 as
bitumen is
collected through the bitumen outlets 212. Solvent, tailings, and/or some
amount of
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bituminous feed (collectively, the "secondary bituminous feed") may pass
through the solvent
and/or tailing outlets 218 and into the secondary separator 302. Solvent may
be injected into
the secondary separator 302 at the solvent injection inlet 303 in order to
alter one or more
characteristics of the secondary bituminous feed, e.g., viscosity, separation,
disaggregation,
etc. It will be noted that a variety of locations are available for placing
the injection inlet 303,
including at each water and/or tailings outlet 218, and such alternate
embodiments are within
the scope of this disclosure. The secondary bituminous feed may be passed
through the
fingers 304 for secondary or second phase separation. Second phase separation
in each of the
fingers 304 may occur in substantially the same the same way as the initial or
first phase
separation in the vessel 202. Specifically, as the secondary bituminous feed
flows across the
secondary hoppers 306, the angle of the wall(s) of each hopper 306 and the
upflow (rise)
created by feed incidence against the wall(s) of each hopper 306 causes
separation according
to known particle settling principles. This process causes hydrocarbons or
bitumen to float to
the top of the fingers 304 where the hydrocarbons or bitumen may be collected
via bitumen
outlets 310. The remainder of the secondary bituminous feed, which may
comprise
substantially tailings, may be discharged through the secondary water and/or
tailings outlets
308. Following discharge, the remaining secondary bituminous feed may be
recirculated
and/or otherwise combined with the bituminous feed, may be sent for further
processing, may
be collected and disposed of as tailings, or may undergo another process as
optionally
determined according to the skill of those in the art.
[0051] FIG. 4 is a block diagram describing a process 400 for recovering
hydrocarbons in
a solvent extraction process. At block 402, the process 400 may pass a
bituminous feed
through an inlet, e.g., the feed inlet 204 of FIG. 2, of a vessel, e.g., the
vessel 202 of FIG. 2.
At block 404, the process 400 may flow the solvent extracted bitumen across a
plurality of
hoppers, e.g., the hoppers 216 of FIG. 2, disposed on a lower end of the
vessel. At block 406,
the process 400 may separate the solvent extracted bitumen to obtain bitumen
and tailings.
Separating the solvent extracted bitumen may include flowing the solvent
extracted bitumen
across the hoppers. In so doing, the angle of the wall(s) of each hopper and
the upflow (rise)
created by feed incidence against the wall(s) of each hopper may cause
separation according
to known particle settling principles, e.g., Stokes' Law settling. At block
408, the process
400 may remove the hydrocarbons and/or solvent extracted bitumen from the
vessel, e.g., via
bitumen outlets 212. At block 410, the process 400 may remove at least a
portion of the
tailings created from the separation process from the vessel. For example, the
tailings may be
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discharged through one or more solvent and/or tailing outlets, e.g., the
solvent and/or tailing
outlets 218 of FIG. 2. At block 412, the process 400 may pass at least a
portion of the solvent
extracted bitumen through an outlet, e.g., the feed outlet 208 of FIG. 2, of
the vessel.
[0052] FIG. 5 is a block diagram describing a continued process 500 for
recovering
hydrocarbons in a solvent extraction process. The process 500 may comprise the
process 400
and may begin after block 412 of FIG. 4. At block 502, the at least a portion
of the solvent
extracted bitumen, or secondary solvent extracted bitumen stream, is passed to
a secondary
separator, e.g., the secondary separator 302 of FIG. 3. At block 504, the
secondary solvent
extracted bitumen stream is fed to at least one secondary vessel finger, e.g.,
a finger 304 of
FIG. 3. At block 506, each finger may separate the secondary solvent extracted
bitumen
stream. For example, each finger may comprise at least one hopper, e.g., a
secondary hopper
306 of FIG. 3, and may flow the secondary solvent extracted bitumen across the
hopper to
obtain a desired settling of the secondary solvent extracted bitumen. At block
508,
hydrocarbons or bitumen may be collected through one or more finger outlets,
e.g., a bitumen
outlet 310, and the remainder of the secondary solvent extracted bitumen,
which may
comprise substantially tailings, may be discharged through one or more
outlets, e.g., solvent
and/or tailings outlets 308 of FIG. 3.
[0053] FIG. 6 is an embodiment of a system 600 for recovering
hydrocarbons from a
bituminous feed in a solvent extraction process. The components of the system
600 may be
substantially the same as the components of the system 300 of FIG. 3 except as
otherwise
noted. The bituminous feed input 602 into the system 600 is configured to
receive a
bituminous feed comprising substantially solvent-extracted bitumen having
agglomerated
solids. The system 600 includes two separator systems 604a and 604b, e.g.,
each a system
300 of FIG. 3, modified as noted herein, arranged in a counter-current
configuration. It will
be appreciated that the systems 604a and 604b each comprise a unitary outlet
for tailings,
e.g., lines 606a and 606b, respectively. The output stream of tailings passed
via line 606a is
passed to the system 604b, e.g., serving as the bituminous feed input into the
system 604b,
while the output stream of tailings from the system 604b passed via line 606b
is passed to a
solids desolventizer 608 in order to thereby pass a stream comprising dry
solids via line 610.
The solvent recovered by the desolventizer 608 may be returned via line 612 to
the stream of
tailings in line 606a for further processing via the system 604b. Bitumen may
exit the system
604a and be split into two lines, 614a and 614b. Line 606a may carry bitumen
to a solvent
recovery unit 616. The solvent recovery unit 616 may separate the received
feed into a
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stream comprising bitumen, passed via line 618, and a stream comprising "neat"
or "lean"
solvent, passed via line 620. The stream comprising neat solvent passed via
line 620 may
join the stream comprising solvent passed via line 612. Line 614b may return
at least a
portion of the bitumen to the inlet of the system 604a. To enable the counter-
current
configuration, rich solvent may exit the system 604b via line 614c and return
to join the
bituminous input feed 602. Although depicted with only two wash stages, i.e.,
the
configuration of systems 604a and 604b, the number of wash stages may be
optionally
extended, e.g., by passing the tailings stream to a series of wash stages
arranged in a counter-
current wash configuration, to meet a specified bitumen recovery requirement.
As will be
understood by those of skill in the art, in a counter-current configuration
neat solvent is
exposed to a solvent-diluted bitumen stream while rich solvent is exposed to a
bitumen
stream without or comprising comparatively less solvent than the solvent-
diluted bitumen,
e.g., the bituminous feed.
[0054] Fig. 6 provides another embodiment wherein the solvent extracted
bitumen is
subjected to a bitumen product cleaning stage. In this embodiment, solvent
extracted
bitumen enters at 602 and is contacted by paraffin-rich stream 614c to promote
partial
deasphalting, or precipitating a portion of the asphaltenes from the
bituminous feed. This
combined stream enters the system 604a to generate an overflow stream
comprising solvent
diluted bitumen 614a (i.e., comprising both solvent and bitumen) and an
underflow stream
containing precipitated asphaltenes, water, and solids passed via line 606a.
This underflow
stream is contacted by recycled paraffin-rich solvent, recycled via solvent
recovery process
desolventizer 608 and 616, and sent to another system 604b. The underflow from
the system
604b is subjected to solvent recovery process desolventizer 608 to generate a
tailings stream
610 containing asphaltenes. The overflow stream 614a from the initial system
604a is
subjected to solvent recovery 616, generating a solvent recycle stream 620 and
a bitumen
product stream 618.
[0055] While the present techniques may be susceptible to various
modifications and
alternative forms, the exemplary embodiments discussed herein have been shown
only by
way of example. However, it should again be understood that the techniques
disclosed herein
are not intended to be limited to the particular embodiments disclosed.
Indeed, the present
techniques include all alternatives, modifications, combinations,
permutations, and
equivalents falling within the scope of the disclosure and appended claims.
