Note: Descriptions are shown in the official language in which they were submitted.
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1 "HIGH RATE FROTH SETTLING UNITS"
2
3 FIELD
4 Embodiments disclosed herein relate to froth separation vessels,
and
more particularly, to froth separation vessels capable of high rate
throughput.
6
7 BACKGROUND
8 Gravity separation vessels are well known in a variety of
industries.
9 Mixtures of liquids, including water and hydrocarbons having different
densities, as
well as solids, generally associated with the water portion, are separated by
gravity
11 in one or more separation vessels.
12 In the case of extraction of bitumen from mined oil sands, the oil
sand
13 is typically mixed with water, which may be hot, for forming a slurry.
The slurry is
14 conditioned and delivered to a primary settling cell (PSC). Droplets of
bitumen
separate from the majority of the solids therein which settle by gravity; the
bitumen
16 rising to the top of the PSC as a froth. Typically about 10% of the
slurry feedstream
17 becomes froth. The froth typically comprises about 55 wt% bitumen, 35
wt% water
18 and 10 wt% fine solids. The froth is thereafter removed from the PSC for
further
19 treatment to remove the water and the fine solids. As is well understood
in the
industry, the froth is diluted with a solvent, naphthenic or paraffinic, and
is separated
21 in a froth separation unit (FSU) to produce diluted bitumen as the
product stream.
22 The FSU is generally a cylindrical vessel having a conical bottom. The
solvent-
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1 diluted froth feed is fed to the vessel intermediate the cylindrical
portion. Typically,
2 about 80% of the feedstream to the FSU becomes diluted bitumen.
3 It is known by those skilled in the art that, in paraffinic froth
treatment,
4 the asphaltenes are partially precipitated and form aggregates or
agglomerates
prior to the FSU, which may trap some of the fine solids therein. The
negatively
6 buoyant agglomerates, as well as the coarser solids and water, settle
within the
7 FSU and are removed from the bottom of the FSU. The cleaned, solvent-
diluted
8 bitumen product (dilbit) is removed from the top of the FSU.
9 The FSU vessel typically comprises a turbulent zone having violent
upward and downward flux therein at the same time. The turbulent zone is
formed
11 about the feed discharge to the vessel. A clarification zone forms above
the feed
12 discharge. Less dense components, such as diluted bitumen, rise in the
clarification
13 zone and are discharged from the vessel at a product outlet at the top
of the vessel.
14 More dense components, such as water, solids, asphaltene agglomerates
and any
solvent and bitumen associated therewith, settle to form a tailings zone below
the
16 turbulent zone. Water droplets comprising solids and the like may be
carried upward
17 into the clarification zone as a result of the turbulent discharge zone.
The water
18 droplets typically coalesce and the coalesced droplets and solids
associated
19 therewith pass downwardly through the turbulent zone to settle to the
bottom of the
FSU. Solvent and diluted bitumen, carried into the tailings zone as a result
of the
21 violent downward flux, pass upwardly through the turbulent zone to enter
the
22 clarification zone. Some solvent and bitumen in the tailings zone,
largely associated
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1 with the asphaltene agglomerates, may be discharged from a tailings
outlet at the
2 bottom of the vessel with the water and solids and can be lost to the
tailings.
3 As one of skill will appreciate, the rate at which the FSU can be
4 operated is largely limited by the turbulent zone. If the vessel is
operated at too high
a rate, a portion of the feed entering the vessel breaks through the
clarification zone
6 and is carried over with the diluted bitumen and solvent at the product
outlet
7 resulting in poor separation. Consequently, asphaltene agglomerates,
solids and
8 water which would normally report to the underflow, report to the
overflow product
9 stream. Such a product will be off-spec and may be unsuitable for use
without
further separation. Further, all of the downstream apparatus, such as solvent
11 recovery units (SRU) and heat exchangers, as well as piping and other
equipment,
12 can require a periodic major cleanup which will result in shutdowns and
loss of
13 productivity with significant cost associated therewith.
14 In conventional paraffinic froth treatment operations, two stages
of
FSUs are generally used to achieve separation of the froth feed. An underflow
from
16 a first stage FSU, comprising a major portion of water, solids,
asphaltene
17 agglomerates from the froth as well as any residual bitumen, is fed to a
second
18 FSU. Typically, additional solvent is added to the underflow to aid in
diluting the
19 residual bitumen and forming additional asphaltene agglomerates which
carry at
least a portion of any remaining water therewith. The overflow from the second
FSU
21 is returned to the first FSU, such as by mixing with the froth
feedstream. The
22 overflow from the first FSU is the product diluted bitumen. As one can
appreciate,
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1 throughput rates must be sufficiently low to avoid breakthrough occurring
therein
2 and affecting separation.
3 Further, lower throughput rates have conventionally resulted in
the
4 need for large diameter FSU vessels or additional FSU vessels which also
increases the overall footprint of the froth settling apparatus. Further, the
overall
6 cost is increased as a result of the manufacture and installation of the
FSUs. Where
7 there are two or more FSUs, the vessels are generally spaced apart for
fire safety
8 reasons to avoid catastrophic loss of additional vessels should the
flammable
9 components in one vessel ignite. Thus, the footprint is even larger.
Further, such
large vessels can typically only be assembled in the field as they are too
large to be
11 fabricated off-site and transported. Assembly of the vessel on-site adds
to the
12 overall cost.
13 Clearly there is a desire for FSU vessels that are capable of
higher
14 flow rates so as to minimize the number of vessels, minimize the overall
footprint
and to reduce the costs of manufacture and installation.
16
17 SUMMARY
18 Embodiments of a froth settling (FSU) system are capable of being
19 operated at flux rates exceeding those in a conventional FSU system as a
result of
the pre-classification of a paraffinic solvent-diluted froth feedstream. Less
dense
21 components of the froth, largely bitumen and solvent, and denser
components,
22 largely water, solids and asphaltene agglomerates, are discharged to
discrete
23 locations within the FSU, forming a substantially non-turbulent interface
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1 therebetween. Residual, minor amounts of less dense components in the
underflow
2 and denser components in the overflow rise and fall substantially
unimpeded
3 through the interface to report with the product overflow and underflow
respectively.
4 As the risk of breakthrough is minimized, the FSU can be operated at higher
than
conventional flux rates.
6 In one broad aspect, a method for producing a solvent diluted
bitumen
7 product from a paraffinic solvent-diluted froth feedstream comprises
classifying the
8 solvent-diluted froth feedstream into a less dense stream having a
majority of
9 solvent and diluted bitumen therein and a more dense stream having a
majority of
water, solids and asphaltene agglomerates therein. The less dense stream is
11 discharged into a froth settling vessel (FSU). The more dense stream, is
discharged
12 spaced below the less dense components, forming an interface therebetween.
13 Solvent and diluted bitumen overflow are removed from a top of the FSU as
the
14 solvent diluted bitumen product. At least water, solids and asphaltene
agglomerates
are removed from a bottom of the FSU as an underflow stream.
16 In another broad aspect, a system for producing a solvent diluted
17 bitumen product from a paraffinic solvent-diluted froth feedstream
comprises a froth
18 settling vessel (FSU) configured for separating the feedstream, by
gravity, into less
19 dense solvent and diluted bitumen, which report as the product to a
product outlet at
a top of the FSU, from more dense water, solids and asphaltene agglomerates,
21 which report as an underflow to an underflow outlet at a bottom of the
FSU. One or
22 more classifier feedwells, positioned upstream from the FSU, receive and
classify
23 the feedstream into a classifier overflow comprising a majority of the
solvent and
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1 diluted bitumen and a classifier underflow comprising a majority of the
water, solids
2 and asphaltene agglomerates. The classifier overflow and underflow are
delivered
3 to discrete, axially spaced apart locations in the FSU for minimizing
turbulence in an
4 interface formed therebetween. A minority of solvent and bitumen in the
classifier
underflow and a minority of water, solids and asphaltenes in the classifier
overflow
6 rise and fall by gravity substantially unimpeded by turbulence through
the interface.
7 In embodiments, the FSU further comprises an upper cylindrical
8 portion having a classifier overflow inlet for receiving the classifier
overflow and a
9 classifier underflow inlet spaced axially therebelow for receiving the
classifier
underflow. The interface forms therebetween. A clarification zone forms above
the
11 classifier overflow inlet for separating the minor amount of water,
solids and
12 asphaltene agglomerates from the classifier overflow therein by gravity.
A tailings
13 zone forms therein below the classifier underflow inlet, for separating
the minor
14 amount of solvent and bitumen from the classifier underflow therein by
gravity. A
lower conical portion had the tailings zone therein and the underflow outlet.
16 In embodiments, the FSU is a first FSU and the underflow is a
first
17 underflow. The system further comprises a second FSU for receiving the
first
18 underflow for separating by gravity therein and forming a second
overflow
19 comprising at least used solvent; and a second underflow comprising
water, solids
and asphaltene agglomerates which are discharged from an underflow outlet from
21 the second FSU.
22 The second overflow, which comprises largely solvent, is recycled
to
23 mix with a bitumen-containing froth for forming the solvent diluted
froth feedstream.
6
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1 In embodiments, a single FSU vessel is used which eliminates the
2 requirement for a second FSU vessel. Advantageously, the single vessel at
a
3 minimum reduces the overall footprint, solvent requirements and solvent
inventory
4 which reduces the overall costs.
In another broad aspect, the FSU vessel is a single FSU vessel
6 comprising an upper portion and a lower portion. A divider is positioned
7 intermediate the upper and lower portion for forming a primary recovery
section
8 thereabove and a secondary recovery section therebelow. The paraffinic
solvent-
9 diluted froth feedstream is fed into the primary recovery section.
Solvent and diluted
bitumen is separated from at least water, solids and asphaltene agglomerates
by
11 gravity in the primary recovery section. The solvent and diluted bitumen
is removed
12 from a top of the primary recovery section as a product overflow stream.
The at
13 least water, solids and asphaltene agglomerates is settled and recovered
as a
14 primary underflow stream at the sloped divider. Shear is applied to the
primary
underflow stream. The sheared primary underflow stream is introduced to the
16 secondary recovery section in the single vessel. Residual solvent and
bitumen is
17 separated from the at least water, solids and asphaltene agglomerates in
the
18 secondary recovery section. The residual solvent and bitumen is removed
from a
19 top of the secondary recovery section as a secondary overflow stream which
is
recycled to a froth feedstream for forming the solvent-diluted froth
feedstream. The
21 at least water, solids and asphaltene agglomerates is removed from a
bottom of the
22 secondary recovery section as a secondary underflow stream.
7
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1 The single vessel is particularly advantageous when combined with
2 one or more classifier feedwells for pre-classifying the solvent diluted
froth
3 feedstream into a less dense classifier overflow and a more dense
classifier
4 underflow for introduction to discrete locations in the primary recovery
section of the
single vessel forming a non-turbulent interface therebetween.
6 Accordingly in another broad aspect, the primary recovery section
has
7 a classifier overflow inlet for receiving the classifier overflow from
the one or more
8 classifier feedwells. A classifier underflow inlet, spaced axially
therebelow, receives
9 the classifier underflow from the one or more classifier feedwells, the
interface being
formed therebetween. A primary clarification zone forms above the classifier
11 overflow inlet for separating the minor amount of water, solids and
asphaltene
12 agglomerates from the classifier overflow rising therethrough. A primary
tailings
13 zone forms below the classifier underflow inlet and above the divider
for separating
14 the minor amount of solvent and bitumen from the classifier underflow
falling
therethrough. A shear loop is fluidly connected to the divider for receiving a
primary
16 underflow from the primary recovery section and mixing with a second volume
of
17 solvent for diluting residual maltenes therein. The primary underflow is
reintroduced
18 as a feed to the secondary recovery section for separation therein.
Residual solvent
19 and bitumen rise through a secondary clarification zone as a secondary
overflow to
a secondary overflow outlet. Water, solids and asphaltenes fall to form a
secondary
21 tailings zone therebelow for discharge therefrom.
22 The secondary overflow is recycled to mix with a bitumen-
containing
23 froth feedstream for forming the solvent-diluted froth feedstream.
8
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1 In another broad method aspect wherein the single high rate FSU is
a
2 single vessel having a primary recovery section, a secondary recovery
section and
3 a divider inserted therebetween, the method, following classifying the
solvent-
4 diluted froth feedstream further comprises discharging the less dense
stream into
the primary recovery section. The more dense stream is discharged into the
primary
6 recovery section, at a position spaced below the discharge of the less
dense
7 components. An interface forms therebetween. The solvent and diluted bitumen
8 separated from the at least water, solids and asphaltene agglomerates by
gravity in
9 the primary recovery section. The solvent and diluted bitumen is removed
from a
top of the primary recovery section as the solvent-diluted bitumen product.
The at
11 least water, solids and asphaltene agglomerates settle at the divider
and are
12 discharged as a primary underflow stream from the primary recovery
section at the
13 divider. The primary underflow stream is sheared and introduced to the
secondary
14 recovery section. Residual solvent and bitumen is separated from the at
least water,
solids and asphaltene agglomerates in the secondary recovery section. The
16 residual solvent and bitumen is removed from a top of the secondary
recovery
17 section as a secondary overflow stream, which is recycled to the froth
feedstream
18 for forming the solvent diluted froth feedstream. The at least water,
solids and
19 asphaltene agglomerates is removed from a bottom of the secondary recovery
section as a secondary underflow stream.
21 In embodiments of the FSU systems taught herein, solvent is
22 recovered from the product in a solvent recovery unit (SRU) and from the
underflow
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1 in a tailings solvent recovery unit (TSRU). Recovered solvent is recycled
for use in
2 the systems.
3 While classifiers capable of imparting sufficient acceleration to
the
4 solvent-diluted froth feedstream for classifying the feedstream into a
less dense
overflow and a more dense underflow can be used, a classifier which permits
the
6 asphaltene to slide along the walls directed to the outlet and which is
capable of
7 flushing an underflow outlet with at least solvent is particularly
advantageous.
8 In embodiments taught herein, the classifier is configured to
permit the
9 asphaltene agglomerates to slide along tapered walls to the outlet and is
operated
such that a split-ratio of the overflow and underflow is controlled to provide
sufficient
11 solvent and bitumen in the underflow to flush asphaltene agglomerates
from the
12 underflow outlet.
13 Accordingly in another broad aspect of the invention, a classifier
for
14 classifying a solvent-diluted bitumen froth feedstream comprises a
classifier
chamber having an outer wall which tapers to a top of the chamber and which
16 tapers to a bottom thereof. An inlet, intermediate the classifier
chamber, feeds the
17 feedstream tangentially thereto. An overflow outlet is at the top of the
chamber. An
18 underflow outlet is at the bottom of the chamber. Acceleration of the
feedsteam
19 within the chamber causes less dense components of the feedstream to rise
through a center of the chamber, as an overflow, to the overflow outlet. More
dense
21 components of the feedstream are thrown toward the outer wall for
sliding
22 therealong, as an underflow, to the underflow outlet.
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1 In yet another broad method aspect, a method for operating the
2 classifier for classifying a solvent diluted froth feedstream into a
classifier overflow
3 comprising a majority of solvent and diluted bitumen therein and a
classifier
4 underflow comprising a majority of at least water, solids and asphaltene
agglomerates therein, comprises: discharging the classifier underflow, sliding
6 downwardly along walls of a chamber, from the underflow outlet, with a
minor
7 amount of solvent and diluted bitumen controlled therein so as to flush
the solids
8 and asphaltene agglomerates from adjacent and within the underflow outlet
for
9 minimizing plugging thereat.
11
12 BRIEF DESCRIPTION OF THE DRAWINGS
13 Figure 1A is a schematic illustrating the flow paths in a
conventional
14 arrangement of first and second froth separation vessels used for prior
art paraffinic
froth treatment processes;
16 Figure 1B is a sectional view of a prior art FSU vessel
illustrative of a
17 turbulent zone formed about a feed discharge to the vessel;
18 Figure 2A is a sectional view of a separation system having an FSU
19 vessel and an upstream classifier feedwell, positioned outside the FSU
according to
embodiments taught herein;
21 Figure 2B is a schematic illustrating an FSU system having primary
22 and secondary FSU vessel according to Fig. 2A
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1 Figure
3 is a sectional view according to Fig. 2A illustrating a valve
2 controlling a classifier overflow to the FSU;
3 Figure
4 is a sectional view according to Fig. 3, illustrating an optional
4 second
addition of paraffinic solvent to the overflow from the classifier prior to
the
FSU vessel;
6 Figure
5 is a sectional view of an embodiment of the separation
7 system according to Fig. 2A, wherein the classifier is positioned inside
the FSU;
8 Figure
6A is a sectional view of a single FSU vessel having an
9
elongate cylindrical portion and a sloped insert positioned intermediate
therein
according to an embodiment;
11 Figure
6B is a sectional view illustrating an alternate configuration for
12 the sloped insert according to Fig. 6A;
13 Figure
7 is a sectional view of a vessel according to Fig. 6A, a
14
classifier being incorporated upstream and outside the vessel, forming a high-
rate
single FSU vessel;
16 Figure
8 is a sectional view according to Fig. 6A, a classifier being
17
incorporated upstream and inside the vessel, forming a high-rate single FSU
vessel;
18 Figure
9A is a sectional view of an embodiment of a classifier suitable
19 for use
with conventional FSU vessels and with single, high rate vessels according
to the embodiments of Figs. 6A to 8 taught herein, for increasing the vessel
21 throughput;
22 Figure
9B is a sectional view of another embodiment of a classifier
23
suitable for use with conventional FSU vessels and with single high rate
vessels
12
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1 according to the embodiments of Figs. 6A to 8 taught herein, for
increasing the
2 vessel throughput;
3 Figure 10 is a schematic of an FSU system according to an
4 embodiment, a continuous water phase being injected into the classifier
overflow
prior to delivery to the FSU vessel;
6 Figure 11 is a schematic of an FSU system according to an
7 embodiment incorporating an electrostatic coalescer operative connected
to the
8 classifier overflow prior to delivery to the FSU vessel for coalescing
water droplets
9 therein; and
Figure 12 is a graph illustrating flux rates at varying solvent-to-bitumen
11 ratios for conventional FSU compared to a single, high-rate FSU
according to an
12 embodiment taught herein.
13
14 DETAILED DESCRIPTION OF EMBODIMENTS
Prior Art
16 Having reference to Fig. 1A, in a conventional paraffinic froth
17 treatment, separation of diluted bitumen and solvent, commonly referred
to as dilbit,
18 from water, solids and asphaltenes typically comprises an arrangement of
a first
19 FSU 10 and a second FSU 12. Froth F diluted with solvent S forms a
solvent diluted
froth feed 14, in which the asphaltenes are partially precipitated. The
solvent diluted
21 froth feed 14 is directed to the first FSU 10. Dilbit separates from the
feed 14 and
22 reports to a top 16 of the first FSU 10, as an overflow product stream
OF1
23 therefrom. Water, fine solids, asphaltene agglomerates and residual
bitumen
13
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1 generally report to a conical bottom 18 of the first FSU 10 and are
directed
2 therefrom through a discharge outlet 19 as an underflow UF1 which forms an
3 influent 20 to the second FSU 12.
4 A second volume of fresh solvent SF2 is typically added to the
underflow stream UF1 to dissolve at least a portion of the residual bitumen.
6 Applicant believes that an additional about 4-5% of bitumen, is dissolved
in the
7 influent 20 to the second FSU 12. "Fresh" solvent can be obtained from a
solvent
8 recovery unit (SRU), a tailings solvent recovery unit (TSRU), a vapor
recovery unit
9 (VRU) or can be purchased.
The product overflow OF2 from the second FSU 12, which is largely
11 used solvent Su, is recycled to the first FSU 10, generally by mixing
with the froth F
12 for diluting the froth F therein and for precipitating a controlled
amount of
13 asphaltenes in the froth F. The product overflow OF2 from the second FSU
12 can
14 be stored in a storage tank prior to recycle to the first FSU.
The product overflow OF1 from the first FSU 10 is directed to a solvent
16 recovery unit (SRU) for removal of solvent therefrom resulting in a
bitumen product
17 stream (not shown). The first FSU overflow OF1 can be stored in a
storage vessel
18 prior to deliver to the SRU.
19 An underflow UF2 from the second FSU 12 is a tailings waste stream
which is directed to one or more tailings solvent recovery units (TSRU) for
recovery
21 of at least residual solvent S therefrom.
22 As noted in the background and illustrated in Fig. 1 B, a prior
art FSU
23 typically comprises a turbulent discharge zone 22, having violent upward
and
14
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1 downward flux occurring at the same time therein. The turbulent discharge
zone 22
2 is formed about a feed discharge 24 into the FSU. A hydrocarbon-rich
clarification
3 zone 26 forms above the feed discharge 24 and turbulent zone 22. Less dense
4 components, such as solvent and diluted bitumen, rise in the
clarification zone 26
and are discharged as an overflow OF at an outlet 28 at the top 16 of the FSU.
6 More dense components, such as water, solids, asphaltene agglomerates and
any
7 solvent and bitumen associated therewith, settle to form a tailings zone
30 below
8 the turbulent zone 22. The settled tailings are discharged from the FSU
as an
9 underflow UF stream.
Less dense constituents of the solvent-diluted froth 14, which are
11 drawn below the turbulent discharge zone 22, and more dense components
of the
12 froth F, which are drawn above the turbulent discharge zone 22 as a
result of the
13 violent upward and downward fluxes therein, pass therethrough during the
settling
14 and clarification process. Thus, the turbulence therein negatively
affects the
separation which occurs in the FSU and affects the rate at which the FSU can
be
16 operated. If the rate is too fast, separation may be minimal, if at all,
resulting in
17 partially separated feed breaking through the clarification zone 26 and
reporting at
18 the top 16 of the FSU. The prior art has typically reduced the
throughput rates and
19 increased the size of the FSU to avoid breakthrough.
21 Current Embodiments
22 Embodiments taught herein minimize the turbulence in the discharge
23 zone 22 in the FSU vessel V to minimize barriers to gravity separation
based upon
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1 density of constituents therein. Further, embodiments herein permit
increased
2 throughput rates, an overall reduced size of the vessel V, reduced
solvent
3 requirements, reduced solvent storage requirements and reduced
manufacturing
4 and installations costs.
Having reference to Figs. 2A to 11, in embodiments, one or more
6 classifier feedwells, referred to herein as classifiers 40, are used to
classify the
7 diluted froth feedstream 14 into less dense and more dense components
prior to
8 delivery to the FSU vessel V.
9 Generally, the classifiers 40 utilize a centrifugal force
sufficiently high
to deliver at least a portion and, in embodiments, a majority, of solids,
water and
11 asphaltenes in the solvent diluted froth 14 to a classifier underflow 42
and at least a
12 portion, again a majority, of diluted bitumen and solvent therein to an
overflow 44.
13 The classifier overflow 44 and underflow 42 report to discrete, axially
spaced-apart
14 locations in the vessel V for forming an interface 54 therebeween having
minimal
turbulence therein, unlike the discharge zone 22 in the prior art vessel V.
16 In embodiments, the classifier 40 accelerates the feed 14 therein
17 greater than 1-G and typically greater than 100-G.
18
19 Conventional FSU vessel system with classifier feedwell
In an embodiment, as shown in Fig. 2A, the one or more classifiers 40
21 classify the feed 14 into a hydrocarbon-rich classifier overflow 44 and
a dense
22 classifier underflow 42, which comprises primarily the water, solids and
23 asphaltenes. The overflow 44 and underflow 42 are then delivered to a
primary or
16
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1 first FSU vessel V1, which is a conventional FSU vessel generally
comprising an
2 upper cylindrical portion 46 and a lower conical portion 48.
3 The classifier overflow 44, which comprises primarily diluted
bitumen
4 and solvent, is introduced at one or more classifier overflow inlets 50
to the
cylindrical portion 46 of the first FSU vessel V1. The clarification zone 26
is formed
6 thereabove. The classifier underflow 42 is introduced into the
cylindrical portion 46
7 of the first vessel V1 through one or more classifier underflow inlets
52, spaced
8 below the overflow inlets 50. The classifier underflow 42 forms the
tailings zone 30
9 below the overflow inlets 50.
The relatively non-turbulent interface 54, between the classifier
11 overflow 44 and the classifier underflow 42, forms between the axially
spaced
12 classifier overflow and underflow inlets 50,52 and between the
clarification zone 26
13 and the tailings zone 30. As a result of the classification of the
feedstream 14 and
14 spaced overflow and underflow discharges to the vessel A, the interface 54
is
sufficiently calm that a majority of the classifier overflow 44 remains
thereabove and
16 a majority of the classifier underflow 42 remains therebelow. Any
residual or minor
17 amounts of solvent and diluted bitumen which report to the tailings zone
30
18 therebelow rise and pass through the interface 54, largely unimpeded,
toward the
19 top 16 of the first vessel V1. Similarly, any residual or minor amounts
of water, fine
solids and asphaltene agglomerates which report to the clarification zone 26
settle
21 under gravity and pass through the interface 54, largely unimpeded,
toward the
22 conical bottom portion 48 of the first vessel V1 for discharge therefrom
at underflow
23 outlet 19.
17
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1 Initial classification of the feed 14 using the one or more
classifiers 40
2 and introduction of the classifier underflow and overflow 42,44 into
discrete portions
3 of the first FSU vessel V1 minimizes the turbulence in the interface 54
within the first
4 FSU V1. This permits the first FSU V1 to be operated at high rates as the
risk of
breakthrough is also minimized.
6 Further, use of the one or more classifiers 40 in combination with
the
7 first FSU vessel V1 increases the capacity of the vessel V, otherwise
having
8 conventional sizing, or alternatively permits the same capacity
throughput to be
9 achieved in a smaller diameter vessel. Where a smaller vessel is used,
further cost
savings are realized as the weight of the vessel is reduced resulting in
reduced
11 support structures and platform and reduced requirements for storage
during
12 maintenance of the vessels. Additionally, vessels can be spaced in
closer proximity
13 as the amount of flammable solvent contained therein is reduced which
permits a
14 reduced footprint and platform associated therewith.
Having reference to Fig. 2B, as in a conventional FSU system, the
16 product overflow OF1 is removed from the outlet 28 at the top 16 of the
first FSU
17 vessel V1. The underflow UF1 discharged from the underflow outlet 19
from the first
18 FSU vessel V1 is delivered to the second FSU vessel V2 for removal of
any residual
19 bitumen and solvent therein. Additional fresh solvent SF is added to the
underflow
stream UF1 prior to introduction to the second FSU vessel V2 for stripping
remaining
21 maltenes therefrom and forming the influent 20 to the second FSU vessel
V2. The
22 underflow UF2 from the second FSU vessel V2 reports to a tailings
solvent recovery
23 unit (TSRU) for recovery of any remaining solvent therein. The overflow
OF2 from
18
CA 02981593 2017-10-03
WO 2015/149181 PCT/CA2015/050265
1 the second FSU vessel V2, which typically contains about 90% used solvent
Su, is
2 recycled into the froth stream F for forming the diluted froth stream 14
prior to the
3 one or more classifiers 40. Asphaltenes precipitating therein as a result
of the
4 solvent addition form asphaltene agglomerates. The asphaltene agglomerates
attract fine solids thereto and are generally associated with at least some
water.
6 Rejection of the asphaltene agglomerates thus aids in improving the
quality of the
7 final diluted bitumen product by removing water and solids therewith.
8 In the embodiment shown in Fig. 3, the classifier 40 is positioned
9 upstream and outside of the first FSU vessel V1. A split-ratio between
hydrocarbon-
rich classifier overflow 44 and more dense classifier underflow 42 can be
controlled
11 by providing one or more valves 56 between the classifier 40 and the
first FSU
12 vessel V1. While valves 56 can be provided for both the classifier
overflow 44 and
13 the classifier underflow 42 to control the percentage of each which
reports to the
14 first FSU vessel V1, in an embodiment, a single valve 56 is used on the
classifier
overflow 44, to effectively control both the overflow 44 and underflow 42. In
16 embodiments, a sensor 58 can be used to monitor a water cut in the
classifier
17 overflow 44.
18 Optionally, as shown in Fig. 4, a second volume 60 of paraffinic
19 solvent S is added to the classifier overflow 44 prior to introduction
to the first FSU
vessel V1. The second addition of solvent 60 acts to reject more asphaltene
from
21 the hydrocarbon-rich classifier overflow stream 44. The rejected
asphaltenes
22 generally agglomerate and capture residual water and solids therewith.
The
23 resulting larger and heavier agglomerates settle rapidly under gravity
in the vessel
19
CA 02981593 2017-10-03
WO 2015/149181 PCT/CA2015/050265
1 V1
These larger, heavier agglomerates settle more readily than asphaltene
2 agglomerates, droplets of water and solids in the classifier overflow 44
that have not
3 had the added second volume of solvent 60. In embodiments, this second
volume
4 of solvent 60 can be fresh solvent SF. Alternatively, and more cost
effective, the
second volume of solvent 60 can be a slipstream of the second FSU vessel
6 overflow OF2, which comprises about 90% used solvent Su or greater.
7 In the
embodiment shown in Fig. 5, the one or more classifiers 40 are
8 positioned within the first FSU vessel V1 environment or interface 54,
yet upstream
9 thereof. The one or more classifiers 40 act therein as a feedwell to
deliver the
classifier overflow 44 into the first FSU vessel V1 adjacent the clarification
zone 26.
11 The underflow 42 is introduced into the first FSU vessel V1, spaced
below the
12 overflow 44 and adjacent the tailings zone 30, the interface 54 forming
13 therebetween. No valves are provided to control the split-ratio.
Instead, the
14 positioning of the one or more classifiers 40, relative to the non-
turbulent interface
54 between the hydrocarbon-rich clarification zone 26 and the tailings zone
30, can
16 be used to determine and affect the efficiency of the classifier 40. In
embodiments,
17 a sensor 58 can be used to monitor a water cut in the classifier
overflow 44.
18 In the
embodiments discussed with respect to Figs. 2A to 5, the
19 overflow OF1 from the first FSU vessel V1 is directed to a solvent
recovery unit
(SRU) for removal of solvent from the diluted bitumen, resulting in a bitumen
21 product having less than 0.5% water by weight.
22
23
CA 02981593 2017-10-03
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1 Single FSU vessel for primary and secondary bitumen recovery
2 Alternatively, as shown in Figs. 6A to 8, embodiments of a single
FSU
3 vessel VS, described in greater detail below, eliminates the need for a
second FSU
4 vessel V2. Thus, the overall cost and footprint can be reduced.
Having reference to Fig. 6A, an embodiment of a single FSU vessel
6 VS comprises a cylindrical portion 70 and a conical bottom portion 72.
The single
7 vessel VS further comprises an internal divider or insert 74 which
effectively divides
8 the single FSU vessel VS into primary 76 and secondary 78 recovery sections
9 within the single FSU vessel VS. The insert 74 is positioned intermediate
the
cylindrical portion 70, forming the primary recovery section 76 thereabove and
the
11 secondary recovery section 78 therebelow. The insert 74 is sloped to aid
in
12 collecting the primary underflow UF1, being the solids, water, asphaltene
13 agglomerates and unrecovered maltene therein for delivery to a shear
loop 80.
14 As shown in Figs. 6A and 6B, the sloped insert 74 can have
alternate
shapes, including, but not limited to, a multi-cone insert (Fig. 6A) having
conical
16 sloped walls and an angled planar insert (Fig. 6B). Primary tailings
underflow UF1 is
17 collected along the insert 74 and is discharged from an outlet 82, at a
lowest
18 elevation or elevations thereof, to the shear loop 80.
19 The multi-cone insert 74 is advantageous in that each cone 84 of
the
multi-cone insert 74 is shallower than would be a single cone or sloped planar
insert
21 and thus, the multi-cones 84 provide a greater height within the
secondary recovery
22 section 78 therebelow for a secondary clarification zone 26b.
Alternatively, use of
23 the multi-cone insert 74 permits the overall vessel height to be
reduced. A further
21
CA 02981593 2017-10-03
WO 2015/149181 PCT/CA2015/050265
1 advantage to the multi-cone insert 74 is that should the outlet 82 to the
shear loop
2 80 at a bottom 86 of one of the cones 84 plug, the collected primary
underflow UF1
3 above the insert 74 can still be delivered to the shear loop 80 through
the outlets 82
4 in the other of the cones 84.
Where there is a desire to simplify the construction of the single FSU
6 vessel VS and to reduce the cost thereof, Applicant believes that a
single cone or
7 planar insert 74 can also be used.
8 Separation of the feed 14 in the primary recovery section 76
occurs
9 basically as in a prior art FSU vessel, as described herein. The less
dense solvent
and diluted bitumen rise from the interface 54 through the primary
clarification zone
11 26a to a top 88 of the single FSU vessel VS for discharge at an outlet
90 as the
12 primary overflow OFi. The primary overflow OF1 is typically discharged
to a surge or
13 overflow drum 92 and then to a solvent recovery unit (SRU). A primary
vapor space
14 94 is provided in the spherical top 88 of the primary recovery section
76. The
denser components, being largely water, solids and asphaltene agglomerates,
16 settle to the sloped insert 74 under the influence of gravity forming
the primary
17 tailings zone 30a thereabove for discharge from the single vessel VS as
the
18 primary, dense underflow UF1.
19 The primary underflow UF1 is collected by the insert 74 and
removed
from the outlet 82 at the bottom 86 of the insert 74, such as through piping
96, and
21 is re-introduced to the single vessel VS into the secondary recovery
section 78
22 below the insert 74 and above the conical bottom 72.
22
1
Separation occurs within the secondary clarification zone 26b in the
2
secondary recovery section 78 of the single vessel VS wherein residual solvent
and
3 diluted bitumen rise therein forming the secondary overflow OF2 which is
4
discharged from a top 98 of the secondary clarification zone 26b, typically to
the
overflow drum 92 and SRU. A relatively small secondary vapor space 100, when
6
compared to the primary vapor space 94, is formed thereabove. The pressure of
the
7
primary separation zone 76 and weight of fluid therein acting above the insert
74 is
8
sufficient to maintain vessel integrity without the need for a larger
secondary vapor
9
space 100. The water, solids and asphaltene agglomerates settle by gravity to
the
conical bottom 72 of the single FSU vessel VS forming a secondary tailings
zone
11 30b
thereabove. The dense, secondary tailings underflow UF2 is discharged from
12 an
underflow outlet 102, typically to the tailings solvent recovery unit (TSRU),
for
13 recovery of residual solvent therefrom.
14 As
will be appreciated by those of skill in the art, the secondary
clarification zone 26b occupies a smaller volume, the displacement of the
sloped
16
insert 74 reducing the cross-sectional area thereabout. The primary underflow
feed
17 UF1
therein comprises primarily solvent with relatively small amounts of bitumen
18
therein and thus, rises quickly at a higher upward flux therein. The secondary
19 tailings zone 30b however, occupies about the same volume as in the
previously
described FSU vessels and in the primary recovery section 76 and thus, there
is
21
substantially no change in the downward flux therein. The secondary overflow
OF2
22 is
removed from the secondary recovery section 78 for reintroduction into the
23
primary recovery section 76, largely as diluent for the froth F, the secondary
23
Date Recue/Date Received 2021-09-22
1 overflow OF2 being largely used solvent Su, such as greater than about
90% used
2 solvent Su, the balance being water, solids and residual bitumen and
asphaltene
3 agglomerates, generally associated with the water.
4 In embodiments, a secondary volume of fresh paraffinic solvent SF2
is
added to the primary underflow UF1, prior to reintroduction to the secondary
6 recovery section 78 of the single FSU vessel VS. An inline mixer 104, in
the shear
7 loop 80, to which the fresh solvent SF2 and primary underflow UF1 are
directed,
8 provides sufficient shear to ensure residual maltenes are dissolved
therein prior to
9 the reintroduction from the shear loop 80 into the secondary recovery
section 78.
The primary overflow OF1 and secondary overflow OF2 can be
11 delivered and stored in separate overflow drums 92 or can be delivered
to a single
12 overflow drum 92 having a weir 106 therein. The segregated, secondary
overflow
13 OF2 can be recycled back into the primary recovery section 76 in the
event an upset
14 in the secondary recovery section 78 occurs. The primary overflow OF1 is
delivered
from the overflow drum 92 to the SRU.
16 In embodiments, an in-line mixer 108 is provided in a feed line
110 to
17 the primary recovery section 76 for mixing the froth F with the secondary
overflow
18 OF2 from the overflow drum 92. The mixer 108 also provides sufficient shear
to
19 ensure residual maltenes in the asphaltene agglomerates are dissolved
therein.
In embodiments, the vapor space 94 in the primary recovery section
21 76, the vapor space 100 in the secondary recovery section 78 and the
overflow
22 drum 92 are fluidly connected to allow for pressure equalization
therebetween.
24
Date Recue/Date Received 2021-09-22
1 In embodiments of the single FSU vessel VS, a height of the
2 cylindrical portion 70 can be elongated compared to that of a prior art
FSU vessel.
3 However, the height, even when the diameter is the same as that of a
conventional
4 FSU vessel, is not increased to the equivalent of the two conventional
FSU vessels
commonly used to achieve the same, or enhanced performance of the single FSU
6 vessel VS.
7 By way of example, for a conventional FSU system having two
8 conventional FSU vessels, each having a diameter of 16m, a vapor space of
8m in
9 height and a conical bottom of about 14m in height, the total height is
about 38m for
each vessel for a total height of about 76m for the system. The total volume
of each
11 vessel is therefore about 4145 m3 and the total volume for the system is
about 8290
12 m3.
13 In an embodiment of the single FSU vessel VS with the insert 74,
as
14 taught herein, where the diameter is also 16m and the upper vapor space
is 8m in
height, the total height of the single vessel VS need only be about 46m, about
a
16 40% reduction in height, to obtain the same throughput as the conventional
two-
17 vessel system. The total volume of the single FSU vessel VS with insert
74 is about
18 5754 m3, which is about a 30% reduction on overall volume.
19
Single, high-rate FSU vessel with classifier feedwell
21 Having reference to Figs. 7 and 8, in embodiments, one or more
22 classifier feedwells 40 are used to classify the feed 14, prior to
delivery to single
23 FSU vessel VS taught herein. As a result of the use of the one or more
classifiers
Date Recue/Date Received 2021-09-22
1 40, the single FSU vessel VS is capable of higher throughputs and thus,
is termed
2 herein a single, high-rate FSU vessel VH.
3 As previously described, examples of classifiers 40 are shown in
Figs.
4 9A and 9B. Classifier overflows 44 and underflows 42 are delivered to the
primary
recovery section 76 of the high-rate FSU vessel VH above the sloped insert 74.
The
6 one or more classifiers 40 are effectively upstream of the primary
recovery section
7 76 and can be positioned outside the vessel (Fig. 7) or inside the vessel
(Fig. 8) as
8 described above.
9 The classifier overflow 44 is introduced to the primary recovery
section
76 through one or more primary overflow inlets 120a to the cylindrical portion
70 of
11 the high-rate FSU vessel VH above the sloped insert 74. The classifier
underflow 42
12 is introduced to the primary recovery section 76 through one or more
primary
13 underflow inlets 121a spaced below the primary overflow inlets 120a and
forming a
14 primary interface 122a therebetween. The primary clarification zone 26a
is formed
above the primary interface 122a and a primary tailings zone 30a is formed
below
16 the primary interface 122a.
17 As is understood in the art, product quality remains relatively
18 consistent as the throughput rate in a conventional FSU increases.
However, as the
19 rate continues to increase it will result in water and solids reporting
to the overflow
or product outlet 28. The introduction of the solids in particular will plug
downstream
21 apparatus, such as heat exchangers in the SRU. The point at which the
water and
22 solids appear in the product is known as the breakthrough flux rate.
Operators of
23 conventional FSU must therefore operate and control the rate at a safe
margin
26
Date Recue/Date Received 2021-09-22
1 below the breakthrough flux rate or risk the increased maintenance costs
and
2 downtime losses which would result from breakthrough.
3 Applicant believes that use of the one or more classifiers 40,
such as
4 cyclones, to pre-classify the feedstream 14 prior to either a
conventional FSU
vessel V or the single FSU vessel VS, with introduction of the classifier
overflow 44
6 and underflow 42 to discrete locations in the FSU V, VS, minimizes or
substantially
7 eliminates breakthrough. Breakthroughs typically result in shut down of
the
8 operation. In the primary recovery zone 76, the majority of the solids
and water in
9 the feed 14 are introduced below the solvent and diluted bitumen and thus,
the
water and solids are not exposed to the upward flux rate which occurs therein.
11 Minor amounts of water and solids which might report to the classifier
overflow 44
12 are sufficiently low so as not to result in plugging and shutdown of the
operation, if
13 the water and solids were to carry over to the product overflow stream OFi.
14 Subsequent settling of the water and solids in the clarification zones
26, 26a,
substantially unimpeded through the interface 54, 122a between the
clarification
16 zones 26, 26a and the tailings zones 30, 30a, further reduces the
potential for
17 breakthrough.
18 Thus, as a result of use of the one or more classifier feedwells
40, the
19 operation of the FSU can be controlled at a throughput rate higher than
that of a
conventional FSU. The one or more classifiers 40 can be high gravitational
force
21 classifiers 40 as shown in Figs. 9A and 9B. The classifier 40 is
operated at relatively
22 high acceleration rates. The higher the rotation and resulting
acceleration within the
23 classifier 40, the more efficiently the classifier 40 performs.
27
Date Recue/Date Received 2021-09-22
1 By way of example, if the breakthrough rate of a conventional FSU
is
2 400 mm/min, a conventional FSU would typically be operated at about 300-320
3 mm/min to avoid breakthough. In embodiments taught herein, the high-rate FSU
4 vessel VH can be operated in excess of the conventional 400 mm/min local
flux
rates during operation without breakthrough. Applicant believes that if
embodiments
6 of vessels taught herein are operated near a breakthrough rate for the
vessel, only
7 small amounts of solids, less than that which would plug the downstream
8 operations, if any, would carry over to the product stream.
9 As one of skill will appreciate, the quality of the secondary
overflow
OF2 is not critical to the overall system as the secondary overflow OF2 is
returned to
11 the primary recovery section 76 for removal of residual water, fine
solids and
12 asphaltenes therefrom.
13 As shown in Fig. 7, in an embodiment of the high rate FSU VH,
where
14 the one or more classifiers 40 are positioned outside the single FSU
vessel VS, a
further or third volume of solvent S3 can optionally be added to the
classifier
16 overflow 44 and mixed in the piping feeding the overflow 44 to the
primary recovery
17 section 76 of the high-rate FSU vessel VH for precipitating additional
asphaltenes
18 and forming agglomerates therefrom, prior to introduction to the primary
recovery
19 section 76 of the high-rate FSU vessel VH. Optionally, a mixer 124 can
be
incorporated for mixing the third volume of solvent S3 with the classifier
overflow 44
21 to ensure asphaltenes agglomerates increase in size prior to the
introduction to the
22 high-rate FSU vessel VH.
28
Date Recue/Date Received 2021-09-22
1 As
shown in Fig. 8, in the embodiment where the one or more
2
classifiers 40 are located within the primary recovery section 76 of the high-
rate
3 FSU
vessel VH, the third volume of solvent S3 can also be added to the classifier
4
overflow 44. The mixer 124 is added to an overflow discharge line 126 from the
one
or more classifiers 40 to ensure sufficient shear is provided to dissolve
maltenes
6
therein prior to discharging the overflow 44 directly into the primary
clarification
7 zone 26a of the primary recovery section 76 of the high-rate FSU vessel
VH.
8 The
third volume of solvent S3 can be clean or fresh solvent SF
9
however, to improve the economics of the system, the third volume of solvent
S3 is
a slipstream of the secondary overflow OF2 from the secondary recovery section
78.
11 The
secondary underflow OF2 comprises greater than about 90% used solvent Su,
12 the balance being water, solids, residual bitumen and asphaltene.
13
Again, in embodiments, the vapor space 94 in the primary recovery
14 section 76, the vapor space 100 in the secondary recovery section 78 and
the
overflow drum 92 are fluidly connected to allow for pressure equalization
16 therebetween.
17 In
embodiments, a total height of the cylindrical portion 46,70 of the
18
vessel, whether a conventional FSU vessel V or a single vessel VS, is relative
to the
19
vessel's diameter. When the diameter can be reduced, such as by use of the one
or
more classifiers 40 to increase the throughput, the overall height of the FSU
vessel
21
V,VS can also be reduced. Thus, significant savings can be realized as not
only is
22 the
vessel V, VS smaller, the amount of solvent S required is less, the solvent
29
Date Recue/Date Received 2021-09-22
1 storage capacity required onsite is reduced and the weight is reduced
allowing
2 support structures and the like to be reduced.
3 By way of example, a single high-rate vessel VH, which includes
the
4 one or more classifiers 40 increases the throughput by about 30%. In this
example,
the diameter of the vessel VH can be reduced by 16%. Thus, a 16m diameter
single
6 vessel VH can be reduced in diameter to about 13.5m, permitting a
reduction in the
7 overall height of the single vessel VH from about 46m to about 38.5m to
obtain the
8 same throughput as a conventional two-vessel FSU system. The total volume
of the
9 single vessel VH is therefore only about 3410 m3.
11 Classifier Feedwell
12 Having reference to Figs. 9A and 9B, embodiments of the classifier
13 feedwell 40, according to embodiments taught herein, apply a centrifugal
force to
14 the solvent diluted froth feed 14 sufficient to generate the classifier
overflow 44
which comprises at least a major portion of the diluted bitumen Bmj and
solvent Smj
16 in the feed 14 and a classifier underflow 42, which comprises at least a
major
17 portion of the water W, fine solids C and asphaltenes A in the feed. As
previously
18 stated, classifiers 40 according to embodiments taught herein create
acceleration of
19 the feed therein above 1-G, and typically above 100-G.
In embodiments, the classifier 40 comprises a generally elongate
21 chamber 130 to which the diluted froth stream 14 is fed. The feed 14 is
delivered
22 tangentially to the classifier chamber 130 at feed inlets 132 which are
intermediate
23 the chamber 130, spaced from an overflow outlet 134 at a top 136 of the
classifier
Date Recue/Date Received 2021-09-22
1 40 and an underflow outlet 138 at a bottom 140 of the classifier 40. An
outer wall
2 142 of the chamber 130 tapers inwardly toward the overflow outlet 134 and
also
3 tapers inwardly toward the underflow outlet 138, forming classifier
chamber 130
4 having a cross-section that is generally diamond or hexagonal-shaped. As
the feed
14 is rotated in the classifier chamber 130, angular acceleration causes
separation
6 of the less dense and more dense components therein. The more dense
solids C
7 and asphaltenes A are caused to be "thrown" to the outer wall 142 of the
chamber
8 130 and slide therealong toward the underflow outlet 138 at the bottom
140.
9 Applicant believes that the size of the asphaltene agglomerates A may be
increased
as a result. The less dense clarified diluted bitumen Bmj and solvent Smj
rises in a
11 center of the chamber 130 for discharge at the overflow outlet 134.
12 In the embodiment shown in Fig. 9B, a cylindrical baffle 144 is
13 positioned about the overflow outlet 134 and extends downward therefrom
into the
14 chamber 130. An angle e between the cylindrical baffle 144 and an
adjacent angled
wall 142 of the classifier chamber 130 is such that solids C, which may reach
the
16 wall 142 in an upper portion of the chamber 130, are obstructed from being
17 discharged through the overflow outlet 134.
18 In embodiments, the split-ratio of the classifier 40 is controlled
as
19 discussed earlier herein. Either the valve 56 is operatively connected
to the
classifier overflow 44 or the classifier 40 is positioned within the vessel
V,VS,
21 relative to the interface 54, 122a, so that the majority of the diluted
bitumen Bmj and
22 solvent Smj reports to the classifier overflow 44. In embodiments, a
minor amount of
23 the diluted bitumen Bmn and solvent Smn is designed to report to the
classifier
31
Date Recue/Date Received 2021-09-22
1 underflow 42 so as to wash or flush asphaltene agglomerates A and solids
C
2 associated therewith from adjacent and within the underflow outlet 138 to
prevent
3 plugging therein. In embodiments, the sensor 58 can be used to monitor a
water cut
4 in the classifier overflow 44.
The minor amount of diluted bitumen Bmn and solvent Smn when
6 delivered to the FSU vessel V,VS, as described herein, separates from the
7 remainder of the underflow 42 and rises substantially unimpeded through
the
8 interface 54,122a therein to report to the vessel's product outlet 28.
9 As will be appreciated, the amount of solvent injected, the type
of
solvent used and the temperature and pressure of the classifier 40 determine
the
11 viscosity of the diluted bitumen. The viscosity and density of the
diluted bitumen
12 determines the magnitude of the centrifugal force required in the
classifier 40 to
13 effectively separate the feed 14 as described herein.
14 In the case where less solvent is used, the temperature can be
increased to reduce the viscosity. Where temperature is increased, pressure is
also
16 increased. As one of skill will appreciate, design of the classifier 40
can take into
17 consideration the total, installed cost of the system, the operating
costs and the
18 desired product quality when determining the optimum pressure and
temperatures
19 conditions, as well as the amount of solvent to be used.
By way of example, for pentane, a solvent-to-bitumen (S:B) ratio can
21 be selected between 0.9 to 1.75 with a temperature range of between 60
to 175 C.
22 Applicant believes that a conventional hydrocyclone, which is
23 designed with an underflow discharge rate, sufficient flush the
underflow outlet 138
32
Date Recue/Date Received 2021-09-22
1 to prevent plugging therein, may also be used as a classifier 40 in
embodiments
2 taught herein.
3
4 Use of a continuous water phase with classifier overflow
A minor amount of oil-wet solids Cm,, which may appear in the
6 classifier overflow 44, are typically aggregated with a minor amount of
asphaltene
7 .. agglomerates Am, therein, increasing the size of the agglomerates A which
aids in
8 .. gravity separation within the FSU vessel V, VS, VH.
9 Asphaltenes are generally described as having hydrophilic
functional
groups embedded in a hydrophobic hydrocarbon structure. Asphaltenes are
surface
11 .. active and it is known that water can associate with the asphaltene
agglomerates A
12 for rejection therewith.
13 Having reference to Fig. 10, in an embodiment, a continuous phase
of
14 .. water W having a low solids content, typically less than 2% solids, is
injected into
.. the classifier overflow 44 prior to discharge into the FSU vessel VS,VH.
The
16 continuous water phase W forms an envelope about the minor amounts of
17 aggregated asphaltene agglomerates Am,, solids Cm, and water VVm, in the
classifier
18 overflow 44, acting to increase the size of the agglomerates A for enhanced
19 separation in the FSU vessel VS, VH. Once discharged into the FSU vessel
VS,VH,
.. the water-enhanced asphaltene agglomerates, report to the tailings zone 30,
30a, in
21 the FSU vessel VS,VH.
22 As shown in Fig. 11, in another embodiment, water W with low
solids
23 content, typically less than about 2%, is injected to the classifier
overflow 44, at a
33
Date Recue/Date Received 2021-09-22
1 minimum as droplets D which are not capable of forming a continuous film
or
2 envelope about the asphaltene agglomerates A. The droplets D act to
initiate an
3 increase in the size of the asphaltene agglomerates A. An electrostatic
coalescer
4 150 is operatively connected to the classifier overflow 44, downstream of
the water
injection for coalescing the water droplets D for forming the film or envelope
around
6 the asphaltene agglomerates A and associated solids S and water W.
7 While embodiments are shown in Figs. 10 and 11 for classifiers 40
8 which are positioned outside the FSU vessel VS,VH, one of skill in the
art will
9 .. appreciate that the concepts are also applicable to systems where the
classifier 40
is positioned within the FSU vessel VS,VH.
11
12 Example of mass balance for a single, high rate FSU vessel
13
14 In a single, high-rate FSU vessel VH, according to an embodiment
taught herein, the mass balance data for three separate examples was modelled.
16 Regardless the dimensions of the vessel VH, the mass balance remains
relatively
17 constant. As one of skill will appreciate, only the throughput changes
with vessel
18 size. The results are shown in Tables A-C below.
19
34
Date Recue/Date Received 2021-09-22
1 Table A
2 Example 1
t/hr Froth Solvent Product Tailings
Maltene 45.1 0 44.4 0.7
Asphaltene 9.9 0 3.5 6.4
Water 35 Trace* Trace* 35.0
Solids 0 0 Trace* 10.0
Solvent 0 100 92.0 8.0
3 *Trace - less than 0.5% of total stream
Solvent/Bitumen Ratio 1.818182
Solvent/Asphaltene Ratio 10.10101
Solid/Bitumen Ratio 0.181818
Water/Asphaltene Ratio 3.535354
Bitumen Recovery 87%
Performance coefficient 3.030469
4
Table B
6 Example 2
t/hr Froth Solvent Product Tailings
Maltene 45.1 0 44.8 0.3
Asphaltene 9.9 0 7.0 2.9
Water 35 Trace* Trace* 35.0
Solids 0 0 Trace* 10.0
Solvent 0 76 69.9 6.1
7 *Trace - less than 0.5% of total stream
8 ___________________________________________
Solvent/Bitumen Ratio 1.381818
Solvent/Asphaltene Ratio 7.676768
Solid/Bitumen Ratio 0.181818
Water/Asphaltene Ratio 3.535354
Bitumen Recovery 94%
Performance coefficient 7.152389
9
35
Date Recue/Date Received 2021-09-22
1 Table C
2 Example 3
t/hr Froth Solvent Product Tailings
Maltene 28.7 0 18.3 0.4
Asphaltene 6.3 0 3.8 2.5
Water 53 Trace* Trace* 53.0
Solids 12 0 Trace* 12.0
Solvent 0 50 44.0 6.0
3 *Trace ¨ less than 0.5% of total stream
Solvent/Bitumen Ratio 1.428571
Solvent/Asphaltene Ratio 7.936508
Solid/Bitumen Ratio 0.342857
Water/Asphaltene Ratio 8.412698
Bitumen Recovery 92%
Performance coefficient 7.085
4
As one of skill will appreciate, the performance of the single, high-rate
6 FSU vessel VH is at least comparable to that of a conventional froth
treatment
7 system having two, conventional FSU's V and operated according to Fig.
1A.
8 Further, Applicant believes, based on testing apparatus as taught
9 herein, that the performance of the single high rate vessel VH exceeds
that of a
conventional two-vessel froth treatment system. As described above, savings in
11 weight, footprint and expense are achieved.
12 By way of example, side-by-side testing of a conventional FSU
vessel
13 V and a single vessel VS incorporating the classifier 40 within the vessel
VS was
14 carried out. The operating conditions, including but not limited to, S:B
ratio of the
FSU product, pressure and temperature, were substantially the same.
16 As one of skill will appreciate the upward velocity of the bitumen
B in
17 the clarification zone 26, 26a, 26b, known generally as flux rate
(mm/min), is
36
Date Recue/Date Received 2021-09-22
1 indicative of the throughput of an FSU vessel. The conventional settler
was able to
2 handle only about 450 mm/min upward flux rate, prior to breakthough which
3 resulted in a catastrophic change in product quality. For such
conventional systems,
4 a 20% design margin is normally considered during scale-up to avoid the
possibility
of such a breakthrough in commercial size units.
6 In contradistinction however, the single high rate FSU vessel VH,
7 according to embodiments taught herein, was capable of handling an upward
flux
8 rate in excess of 600 mm/min, without visual indication of breakthrough.
The
9 product quality was maintained at visually acceptable levels throughout.
Applicant believes that the results support the concept that the faster
11 the classifier 40 is operated, the better it enhances the separation of
the feed due to
12 increased rotational speed inside the classifier 40. The increased
rotational speed
13 results in higher acceleration and enhanced separation of dense media
from lighter
14 diluted bitumen B therein.
As will be appreciated, based upon results from testing, one may
16 design a commercial scale operation at even higher rates than 600 mm/mm.
17 Having reference to Fig. 12, pilot testing was performed to
compare
18 the flux rates of a conventional FSU vessel with those possible using an
19 embodiment of the single high-rate FSU as taught herein, the classifier
40 being
positioned internal to the single FSU vessel VS.
21 As can be seen in the graph, flux rates at which the high-rate FSU
can
22 be operated are significantly higher than the maximum flux rates for
conventional
23 FSU, across the entire range of S:B ratios tested.
37
Date Recue/Date Received 2021-09-22
1 As one of skill will appreciate, the test results are
illustrative of the
2 ability to operate the high-rate FSU at flux rates which are
significantly higher than
3 those of conventional FSU without catastrophic breakthrough, but are in no
way
4 intended to demonstrate an upper limit for the flux rate possible using
such a novel
and inventive high-rate FSU.
6
38
Date Recue/Date Received 2021-09-22
