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Patent 2614669 Summary

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(12) Patent: (11) CA 2614669
(54) English Title: AN IMPROVED PROCESS FOR RECOVERING SOLVENT FROM ASPHALTENE CONTAINING TAILINGS RESULTING FROM A SEPARATION PROCESS
(54) French Title: PROCESSUS AMELIORE PERMETTANT DE RECUPERER UN SOLVANT D'ASPHALTENE CONTENANT UN REFUS RESULTANT D'UN PROCEDE DE SEPARATION
Status: Granted
Bibliographic Data
(51) International Patent Classification (IPC):
  • C10C 3/00 (2006.01)
  • B03B 9/02 (2006.01)
(72) Inventors :
  • SURY, KEN (Canada)
(73) Owners :
  • IMPERIAL OIL RESOURCES LIMITED (Canada)
(71) Applicants :
  • IMPERIAL OIL RESOURCES LIMITED (Canada)
(74) Agent: BORDEN LADNER GERVAIS LLP
(74) Associate agent:
(45) Issued: 2008-12-30
(22) Filed Date: 2007-05-03
(41) Open to Public Inspection: 2007-09-30
Examination requested: 2007-11-30
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): No

(30) Application Priority Data: None

Abstracts

English Abstract

A process for recovering paraffinic solvent from tailings produced in the treatment of bitumen froth comprising introducing the tailings into a tailings solvent recovery unit (TSRU), the TSRU having internals, and distributing the tailings over the internals. An inert gas or steam is then introduced below the internals and above the liquid pool for enhancing the vaporization of the contained solvent. Solvent is vaporized from asphaltene agglomerates. In one embodiment, the process is effected in the absence of mechanical means used to substantially break up asphaltene agglomerates or to prevent the agglomeration of asphaltene. In another aspect, the process comprises introducing the tailings into a first TSRU as described above and then into a second TSRU operated at a lower pressure. In another aspect, internals are optionally present and steam or inert gas is injected in the liquid pool.


French Abstract

Procédé permettant de récupérer un solvant paraffinique à partir des queues de distillation issues du traitement de l'écume de bitume; le procédé consiste à introduire les queues de distillation dans une unité de récupération du solvant des queues de distillation (URSQ), cette URSQ renfermant des fractions internes, et distribuant les queues de distillation dans celles-ci. Un gaz inerte ou une vapeur est alors introduit(e) sous les fractions internes et au-dessus du pool de liquide afin d'améliorer la vaporisation du solvant. Le solvant est vaporisé à partir des agglomérats d'asphaltène. Selon un mode de réalisation, le procédé est effectué en l'absence d'un moyen mécanique pour fractionner substantiellement les agglomérats d'asphaltène ou pour prévenir l'agglomération de l'asphaltène. Dans un autre mode de réalisation, le procédé consiste à introduire les queues de distillation dans une première URSQ, comme on le décrit précédemment, mais sous une pression plus faible. Dans un autre mode de réalisation, les fractions internes sont présentes de manière facultative, et une vapeur ou un gaz inerte est injecté(e) dans le pool de liquide.

Claims

Note: Claims are shown in the official language in which they were submitted.





CLAIMS:

1. A process for recovering paraffinic solvent from froth treatment tailings
produced in the
treatment of bitumen froth comprising:
introducing the froth treatment tailings into a first tailings solvent
recovery unit (TSRU),
the first TSRU having internals;
distributing the froth treatment tailings over the internals to increase the
surface area of the
froth treatment tailings;
introducing inert gas or steam below the internals so that it flows counter
currently to the
froth treatment tailings and heats the froth treatment tailings to vaporize at
least a portion of the
paraffinic solvent;
removing the vaporized solvent from the first TSRU;
feeding tailings from the first TSRU into a second TSRU maintained at an
absolute
pressure that is lower than the pressure of the first TSRU, the second TSRU
having internals;
distributing the tailings from the first TSRU over the internals of the second
TSRU to
increase the surface area of the tailings from the first TSRU;
introducing inert gas or steam below the internals of the second TSRU so that
it flows
counter currently to the tailings from the first TSRU and heats the tailings
from the first TSRU to
vaporize at least a portion of the paraffinic solvent; and
removing the vaporized solvent from the second TSRU.


2. The process of claim 1, wherein the first TSRU has an absolute pressure of
about 100 and
200 kPa and the second TSRU has an absolute pressure of 20 to 200 kPa.


3. The process of claim 1 or 2, wherein the internals comprise interior,
vertically spaced shed
decks.


4. The process of any one of claims 1 to 3, wherein the inert gas or steam
introduced below
the internals is introduced above a liquid level in the first and second
TSRU's.


5. The process of any one of claims 1 to 4, wherein the paraffinic solvent is
a C4 to C6
paraffinic hydrocarbon solvent.


6. The process of any one of claims 1 to 5, wherein the paraffinic solvent is
pentane, iso-
pentane, or a combination thereof.



-14-




7. The process of any one of claims 1 to 6, wherein the second TSRU has an
absolute
pressure of about 20kPa to less than 170 kPa.


8. The process of any one of claims 1 to 7, wherein the second TSRU has an
absolute
pressure of about 35 kPa to about 125 kPa.


9. The process of any one of claims 1 to 8, wherein the second TSRU has an
absolute
pressure of about 35 kPa to about 100 kPa.


10. The process of any one of claims 1 to 9, wherein the temperature of the
second TSRU is
about 75 to about 100°C.



-15-

Description

Note: Descriptions are shown in the official language in which they were submitted.



CA 02614669 2007-11-30

AN IMPROVED PROCESS FOR RECOVERING SOLVENT FROM ASPHALTENE
CONTAINING TAILINGS RESULTING FROM A SEPARATION PROCESS

This application is a divisional application of co-pending application Serial
No.
2,587,166, filed May 3, 2007.

FIELD OF THE INVENTION

[0001] The present invention relates generally to an improved process for
recovering
solvent from asphaltene containing tailings resulting from a separation
process. More particularly,
the invention relates to recovering paraffinic solvent from such tailings.

BACKGROUND OF THE INVENTION

[0002] The extraction of bitumen from mined oil sands involves the liberation
and
separation of bitumen from the associated sands in a form that is suitable for
further processing to
produce a marketable product. Among several processes for bitumen extraction,
the Clark Hot
Water Extraction (CHWE) process represents a well-developed commercial
recovery technique. In
the CHWE process, mined oil sands are mixed with hot water to create slurry
suitable for
extraction. Caustic is added to adjust the slurry pH to a desired level and
thereby enhance the
efficiency of the separation of bitumen. Recent industry developments have
shown the feasibility
of operating at lower temperatures and without caustic addition in the
slurrying process.

[0003] Regardless of the type of water based oil sand extraction process
employed, the
extraction process will typically result in the production of a bitumen froth
product stream
comprising bitumen, water and fine solids (also referred to as mineral matter)
and a tailings stream
consisting of essentially coarse solids and some fine solids and water. A
typical composition of
bitumen froth is about 60 wt% bitumen, 30 wt% water and 10 wt% solids, with
some variations to
account for the extraction processing conditions. The water and solids in the
froth are considered
as contaminants and must be either essentially eliminated or reduced to a
level suitable for feed to
an oil refinery or an upgrading facility, respectively. The contaminants
rejection process is known
as a froth treatment process and is achieved by diluting the bitumen froth
with a sufficient quantity
of an organic solvent such as naphtha. There are two commercial approaches to
reject the froth
contaminants, namely naphtha based and paraffinic solvent based. Solvent
addition (dilution)
increases the density differential between bitumen and water and solids and as
well enable the
contaminants rejection using multi-stage gravity settling units. The
separation schemes generally
result in a bitumen diluted product and another tailings stream, commonly
referred to as the froth
treatment tailings, containing residual bitumen, residual solvent, solids and
water. The froth
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CA 02614669 2007-11-30

treatment tailings stream must be processed further to recover the residual
solvent and be suitable
for disposal. Residual solvent recovery is dictated by both environmental and
economic reasons.
This recovery operation is referred to as a tailings solvent recovery process.

[0004] In the naphtha based separation, the resulting bitumen product contains
1 to 3 wt%
water and < 1.0 wt% solids and is not suitable for transporting through a
common pipeline carrier.
The addition of sufficient amounts of paraffinic solvent results in asphaltene
precipitation,
formation of aggregates with the contaminants (entrained water and carryover
solids in the froth)
and a rapid settling to provide a solids free dry bitumen product suitable for
transportation in a
conunon carrier and to refmeries.

[0005] The addition of paraffinic solvent to bitumen froth and the resulting
benefits are
described in Canadian Patents Nos. 2,149,737 and 2,217,300. According to
Canadian Patent No.
2,149,737, the efficiency (rate and extent) of removal of water and solids
generally increases as (i)
the carbon number or molecular weight of the paraffinic solvent decreases,
(ii) the solvent to froth
ratio increases, and (iii) the amount of aromatic and napthene impurities in
the paraffinic solvent
decreases. The inventors further demonstrated that the separation of water and
solids from the
bitumen is achieved at temperatures above 30 C. The effect of temperature on
bitumen recovery
and bitumen product quality obtainable in this separation process was studied
in a scale up pilot
using natural gas condensate (NGC) which contains about 83% paraffin. While
bitumen recovery
was higher (97.6 vs. 83.8 wt%) if the run was conducted at 117 C, the product
quality obtained
was significantly lower (99.2 vs. 90.6 wt%) than obtained at 50 C. In
accordance with the one of
the discoveries stated above, the inventors used a relatively high
solventlfroth ratio to obtain a
better product quality with NGC in a continuous process but this test was done
at 50 C. Although
the inventors obtained a satisfactory product quality using pure paraffinic
solvents at laboratory
conditions and up to 80 C, it was not obvious such a result would be
duplicated at a pilot scale
continuous test unit due to uncertain hydrodynamics as well as increasing
solubility of water in
hydrocarbon at higher temperatures. In general, in a continuous separation,
product quality and
yield are inter-related and judicious fine-tuning of process parameters is
required to establish
optimum quality for a given yield. As discussed above, the froth treatment
process must have a
reliable and economic technique for solvent recovery from the tailings.
However, the unique
nature of the solvent-containing tailings makes solvent removal a challenge to
the industry.
Various processes have been devised for recovering solvent from solvent-
containing tailings, some
of which will now be described.

[0006] Canadian Patent No. 1,027,501 describes a process for treatment of
tailings to
recover naphtha. The process comprises introducing the tailings into a
distributor at the upper end
of the chamber of a vacuum flash vessel or tower maintained at 35 kPa, in
order to flash the
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CA 02614669 2007-11-30

naphtha present in the tailings. The vessel is also equipped with a stack of
internal shed decks for
enhancing contact between stripping steam and the tailings feed. The steam is
introduced at a point
above the liquid pool in the vessel and below the stack of shed decks. The
steam is intended to heat
the flashed tailings as they pass down through the shed decks, to vaporize
contained solvent and
some water, for recovery as an overhead stream. In practice, however, this
process results in only
60 to 65% recovery of the solvent; hence, a large amount of solvent is still
being released to the
environment.

[0007] Canadian Patent No. 2,272,045 describes a method for recovery of
hydrocarbon
solvent from tailings produced in a bitumen froth treatment plant comprising
introducing the
tailings into a steam stripping vessel maintained at near atmospheric
pressure, the vessel having a
plurality of interior, vertically spaced shed decks, and distributing the
tailings over said shed
decks. Steam is introduced below the shed decks for vaporizing the major
portion of the contained
solvent and some water. However, the tailings are free of asphaltenes
according to page 4, lines 11
to 13. Canadian Patent No. 2,272,035 describes a process for recovery of
hydrocarbon solvent
from tailings produced in a bitumen froth treatment plant comprising
introducing the tailings into a
vacuum flash vessel maintained at a sufficiently low sub-atmospheric pressure
to vaporize the
major portion of the contained solvent and some water. The residuals then pool
near the bottom of
the flash vessel. Steam is then introduced into the tailings pool for
vaporizing residual solvent and
some water. However, as with Canadian Patent No. 2,272,045, discussed above,
the tailings are
free of asphaltenes according to page 4, lines 12 to 15. Thus, the inventors
of these two patents did
not have to contend with the challenges associated with having asphaltenes in
the tailings. Certain
of such challenges are discussed below with reference to Canadian Patent No.
2,353,109 and
Canadian Patent Application No. 2,454,942.

[0008] Canadian Patent No. 2,353,109 describes a process for treating an
underflow
stream (or tailings) containing water, solvent, asphaltenes and solids, from
one of the last
separation steps in a paraffinic solvent process for separating bitumen from
an oil sands froth,
wherein a) the stream is introduced to a solvent recovery vessel that is
substantially free of
internals wherein the temperature and pressure are such that the solvent is
normally a vapor; b) a
pool of liquid and solids is maintained in the lower part of the vessel at a
controlled level for
sufficient time to allow the solvent to vaporize; c) the pool is agitated to
the point where the
asphaltenes are dispersed, submerged and prevented from re-agglomerating and
the solids are
maintained in suspension; d) the solvent is recovered as an overhead vapor
stream; and e) the
solvent depleted remainder of the stream is removed from the bottom of the
vessel as a liquid
slurry. Agitation is preferably effected by means of an impeller. An alternate
agitation means is a
pump-around circuit to pump the slurry from the top of the liquid pool to the
lower part of the
-3-


CA 02614669 2007-11-30

liquid pool or vice versa. The typical composition of this underflow stream is
described as about
40 to 60 wt% water, about 15 to 35 wt% mineral solids (sand and clay), about 5
to 15 wt%
entrained solvent, and about 10 to 15 wt% asphaltenes and unrecovered bitumen.
Page 3, second
full paragraph of that patent describes (a) that conventional solvent
technology employs vessels
with internals such as trays, packing and baffles; (b) that such internals
provide the residence time
required for the necessary solvent vaporization to take place; (c) that
vessels with such internals
are not practical for an underflow stream having the aforementioned
composition; (d) that the
aforementioned conventional approach is unworkable because of the accumulation
of inorganic
and organic solids and the fouling or plugging of vessel internals, lines and
valves; and (e) that in
that invention, the necessary residence time is achieved by having a liquid
pool form in the lower
part of the vessel. The invention teaches that agitation must be provided in
or around the solvent
recovery unit primarily to disperse or prevent the growth of aggregates of
precipitated asphaltenes
thereby enhancing the release of solvent from the precipitated asphaltenes to
the vapor phase. In
one embodiment, first and second stage solvent recovery vessels are used,
where the second stage
vessel is typically operated at a reduced pressure relative to the first stage
vessel to reduce any
amount of foam that may still be associated with the liquid slurry removed
from the bottom of the
first stage vessel. The second stage vessel is mechanically identical to the
first stage vessel.
[0009] Canadian Patent Application No. 2,454,942 describes a process for
solvent
recovery from froth treatment tailings comprising water, particulate solids,
and precipitated
asphaltenes. According to the inventors, recycling a pre-determined portion of
the solvent
recovered tailings stream to the solvent recovery apparatus is necessary to
maintain downward flux
in the apparatus which inhibits accumulation of asphaltene mat in the solvent
recovery unit and
suppress the formation of foam. Furthermore, shearing conditions (provided by
pumps, mixers or
another apparatus) is preferably provided in the recycle circuit first, to
break up asphaltene
flocs/aggregates and second, to enhance recovery of solvent from the tailings.
There is no
introduction of steam or inert gas to vaporize solvent from the asphaltenes.

[0010] Thus, Canadian Patents Nos. 2,272,045 and 2,272,035 deal with solvent
recovery
from tailings that are free of asphaltenes. Canadian Patent No. 2,353,109
deals with solvent
recovery without the use of internals. Canadian Patent Application No.
2,454,942 deals with
solvent recovery without the introduction of steam or inert gas to vaporize
solvent from the
asphaltenes. Both of Canadian Patent No. 2,353,109 and Canadian Patent
Application No.
2,454,942 deal with solvent recovery from tailings containing asphaltenes
using agitation or
shearing in or around the recovery vessel, so that the asphaltenes are
dispersed, submerged and
prevented from re-agglomerating.

-4-


CA 02614669 2007-11-30
SUMMARY OF THE INVENTION

[0011] It is an object of the present invention to obviate or mitigate at
least one
disadvantage of previous processes.

[0012] In a first aspect, the present invention provides a process for
recovering paraffinic
solvent from froth treatment tailings produced in the treatment of bitumen
froth comprising:
introducing the froth treatment tailings into a tailings solvent recovery unit
(TSRU), the TSRU
having internals, and distributing the froth treatment tailings over the
internals to increase the
surface area of the froth treatment tailings; introducing inert gas or steam
below the internals so
that it flows counter currently to the froth treatment tailings and heats the
froth treatment tailings to
vaporize at least a portion of the paraffinic solvent; and removing the
vaporized solvent from the
TSRU; wherein the froth treatment tailings contain asphaltenes; and wherein
the at least a portion
of the solvent is vaporized from asphaltene agglomerates.

[0013] Within this first aspect, the following embodiments may be included.
The process
may be effected in the absence of inechanical means used to substantially
break up asphaltene
agglomerates or to prevent the agglomeration of asphaltene. The TSRU may have
an absolute
pressure of about 100 and about 200 kPa. The internals may comprise a
plurality of interior,
vertically spaced shed decks. The internals may be coated with an asphaltene
fouling resistant
coating to mitigate fouling or plugging in the TSRU. The froth treatment
tailings may contain at
least 1.0 wt% asphaltenes, or at least 5.0 wt% asphaltenes. The inert gas or
steam introduced
below the internals may be introduced above a liquid level that forms in the
bottom of the TSRU.
The paraffinic solvent may be a C4 to C6 paraffinic hydrocarbon solvent. The
paraffinic solvent
may be pentane, iso-pentane, or a combination thereof. The temperature of the
TSRU may be
about 75 to about 100 C. The TSRU may have an absolute pressure of about 120
to about 170
kPa. The inert gas may be nitrogen, methane, carbon dioxide, argon, steam or
any other inert gas
that is not reactive under process conditions. The inert gas or steam to froth
treatment tailings
mass ratio may be about 1:1 to about 10:1. The process may further comprise:
feeding tailings
from the TSRU into a second TSRU maintained at an absolute pressure that is
lower than the
pressure of the TSRU recited above, the second TSRU having internals, and
distributing the
tailings from the TSRU over the internals to increase the surface area of the
tailings from the
TSRU; introducing inert gas or steam below the internals of the second TSRU so
that it flows
counter currently to the tailings from the TSRU and heats the tailings from
the TSRU to vaporize
at least a portion of the paraffinic solvent; and removing the vaporized
solvent from the second
TSRU. The second TSRU may have an absolute pressure of about 20 to about 200
kPa. The
internals of the second TSRU may comprise a plurality of interior, vertically
spaced shed decks.
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CA 02614669 2007-11-30

The inert gas or steam introduced below the internals in the second TSRU may
be introduced
above a liquid level that forms in the bottom of the second TSRU. The second
TSRU may have an
absolute pressure of about 35 kPa to about 125 kPa, or about 35 kPa to about
100 kPa. The
temperature of the second TSRU may be about 75 to about 100 C.

[0014] In a second aspect, the present invention provides a process for
recovering
paraffinic solvent from froth treatment tailings produced in the treatment of
bitumen froth
comprising: introducing the froth treatment tailings into a first tailings
solvent recovery unit
(TSRU), the first TSRU having internals; distributing the froth treatment
tailings over the internals
to increase the surface area of the froth treatment tailings; introducing
inert gas or steam below the
internals so that it flows counter currently to the froth treatment tailings
and heats the froth
treatment tailings to vaporize at least a portion of the paraffinic solvent;
removing the vaporized
solvent from the first TSRU; feeding tailings from the first TSRU into a
second TSRU maintained
at an absolute pressure that is lower than the pressure of the first TSRU, the
second TSRU having
internals; distributing the tailings from the first TSRU over the internals of
the second TSRU to
increase the surface area of the tailings from the first TSRU; introducing
inert gas or steam below
the internals of the second TSRU so that it flows counter currently to the
tailings from the first
TSRU and heats the tailings from the first TSRU to vaporize at least a portion
of the paraffinic
solvent; and removing the vaporized solvent from the second TSRU.

[0015] Within this second aspect, the following embodiments may be included.
The
TSRU may have an absolute pressure of about 100 and 200 kPa and the second
TSRU may have
an absolute pressure of 20 to 200 kPa. The internals may comprise interior,
vertically spaced shed
decks. The insert gas or steam introduced below the internals may be
introduced above a liquid
level in the first and second TSRU's. The froth treatment tailings may contain
asphaltenes, at least
a portion of the solvent may be vaporized from asphaltene agglomerates, and
the process may be
effected in the absence of mechanical means used to substantially break up
asphaltene
agglomerates or to prevent the agglomeration of asphaltene. The froth
treatment tailings may
contain at least 1.0 wt% asphaltenes, or at least 5.0 wt% asphaltenes. The
paraffinic solvent may
be a C4 to C6 paraffinic hydrocarbon solvent. The paraffinic solvent may be
pentane, iso-pentane,
or a combination thereof.

[0016] In a third aspect, the present invention provides a process for
recovering paraffinic
solvent from froth treatment tailings produced in the treatment of bitumen
froth comprising:
introducing the froth treatment tailings into a tailings solvent recovery unit
(TSRU); introducing
inert gas or steam into a liquid pool formed in the bottom of the TSRU to
vaporize at least a
portion of the paraffinic solvent; and removing the vaporized solvent from the
TSRU; wherein the
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CA 02614669 2007-11-30

froth treatment tailings contain asphaltenes; and wherein the at least a
portion of the solvent is
vaporized from asphaltene agglomerates.

[0017] Within this third aspect, the following embodiments may be included.
The TSRU
may be substantially free of internals. The process may be effected in the
absence of mechanical
means used to substantially break up asphaltene agglomerates or to prevent the
agglomeration of
asphaltene. The froth treatment tailings may contain at least 1.0 wt%
asphaltenes, or at least 5.0
wt% asphaltenes. The TSRU may have an absolute pressure of about 20 and about
200 kPa. The
paraffinic solvent may be a C4 to C6 paraffmic hydrocarbon solvent. The
paraffinic solvent may be
pentane, iso-pentane, or a combination thereof. The temperature of the TSRU
may be about 75 to
about 100 C. The process of may further comprise feeding tailings from the
TSRU into a second
TSRU maintained at an absolute pressure that is lower than the pressure of the
TSRU recited
above.

[0018] Other aspects and features of the present invention will become
apparent to those
ordinarily skilled in the art upon review of the following description of
specific embodiments of
the invention in conjunction with the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the present invention will now be described, by way of
example
only, with reference to the attached Figure, wherein:
[0020] Fig. 1 is a schematic of a diluted bitumen froth treatment process,
including a
tailings solvent recovery process according to an embodiment of the present
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS

[0021] Generally, the present invention provides, in one aspect, a process for
recovering
paraffinic solvent from tailings produced in the treatment of bitumen froth
comprising introducing
the tailings into a tailings solvent recovery unit (TSRU), the TSRU having
internals, and
distributing the tailings over the internals. An inert gas or steam is then
introduced below the
internals for enhancing the vaporization of the contained solvent. Solvent is
vaporized from
asphaltene agglomerates. In one embodiment, the process is effected in the
absence of inechanical
means used to substantially break up asphaltene agglomerates or to prevent the
agglomeration of
asphaltene. In another aspect, the process comprises introducing the tailings
into a first TSRU as
described above and then into a second TSRU operated at a lower pressure.

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CA 02614669 2007-11-30

[0022] It has been shown that prior art methods of agitation or use of
shearing devices in
the recovery of solvent from diluted tailings containing asphaltene
agglomerates actually results in
significant increase in operability problems such as plugging and fouling as
well as lower solvent
recovery.
[0023] Figure 1 is a schematic of a diluted bitumen froth treatment process,
including a
tailings solvent recovery process according to an embodiment of the present
invention. The
paraffinic solvent diluted bitumen froth (2) enters froth separation unit FSU
(4).

[0024] The diluted bitumen froth (2) may be produced in a number of ways known
in the
art and comprises bitumen, asphaltenes, mineral solids, water, and a
paraffinic solvent.

[0025] The diluted bitumen froth (2) contains a paraffinic solvent because
such a solvent
has been added to a bitumen froth to induce precipitation of a portion of the
asphaltenes present in
bitumen, aggregation with water droplets and solids present in froth and
settling rapidly in a
gravity settler (FSU).

[0026] The term "paraffinic solvent" (also known as aliphatic) as used herein
means
solvents containing normal paraffins, isoparaffins and blends thereof in
amounts greater than 50
wt%. Presence of other components such as olefins, aromatics or naphthenes
counteract the
function of the paraffinic solvent and hence should not be present more than 1
to 20 wt%
combined and preferably, no more than 3 wt% is present. The paraffinic solvent
may be a C4 to C20
paraffinic hydrocarbon solvent or any combination of iso and normal components
thereof. In one
embodiment, the paraffinic solvent comprises pentane, iso-pentane, or a
combination thereof. In
one embodiment, the paraffinic solvent comprises about 60 wt% pentane and
about 40 wt% iso-
pentane, with none or less than 20 wt% of the counteracting components
referred above.

[0027] By using a blend of pure paraffins and operating at a temperature range
of 70 to
90 C in a continuous separation unit as shown in Fig 1, it is possible to
achieve both a high quality
(containing <0.01 wt%, or at least <0.5 wt. %, water+solids) and a high yield
(98 wt%) bitumen
product.

[0028] With the addition of a sufficient amount of paraffinic solvent, and by
way of
gravity settling, the diluted bitumen froth (2) separates in FSU (4) into a
diluted bitumen
component (6) comprising bitumen and solvent and a froth treatment tailings
component (8)
comprising mainly of water, mineral matter, precipitated asphaltenes, solvent,
and very small
amounts of unrecovered bitumen. The tailings stream (8) may be withdrawn from
the bottom of
FSU (4), which may be conical. In one embodiment, FSU (4) operates at a
temperature of about
60 C to about 80 C, or about 70 C. In one embodiment, FSU (4) operates at a
pressure of about
700 to about 900 kPa, or about 800 kPa.

-8-


CA 02614669 2008-04-29

[0029] Diluted bitumen component (6) is passed through a solvent recovery
unit, SRU
(10), such as a conventional fractionation vessel or other suitable apparatus
in which the solvent
(12) is flashed off and condensed in a condenser associated with the solvent
flashing apparatus and
recycled/reused in the process. The solvent free bitumen product (14) is then
stored or transported
for further processing in a manner well known in the art.

[0030] Froth treatment tailings component (8) may be passed directly to the
tailings
solvent recovery unit, TSRU, (16) or may, as shown in Figure 1, first be
passed to a second FSU
(18). Diluted tailings component (8) may typically comprise approximately 50
to 70 wt% water,
to 25 wt% mineral solids, and 5 to 25 wt% hydrocarbons. The hydrocarbons
comprise
10 asphaltenes (for example 2.0 to 12 wt% or 9 wt% of the tailings), bitumen
(for example about 7.0
wt% of the tailings), and solvent (for example about 8.0 wt% of the tailings).
In further
embodiments, the tailings comprise greater than 1.0, greater than 2.0, greater
than 3.0, greater than
4.0, greater than 5.0, or greater than 10.0 wt% asphaltenes.

[00311 Tailings component (8) is a tailings stream generated in a paraffinic-
based
15 bitumen froth treatment process or other separation process and while
certain means resulting in a
froth treatment tailings component have been described above, the present
invention is not limited
thereby.

[0032] FSU (18) performs generally the same function as FSU (4). The operating
temperature of FSU (18) may be higher than that of FSU (4) and may be between
about 80 C and
about 100 C, or about 90 C. In one embodiment, FSU (18) operates at a pressure
of about 700 to
about 900 kPa, or about 800 kPa. A diluted bitumen component stream (20)
comprising bitumen
and solvent is removed from FSU (18) and is either sent to FSU (4) feed for
use as solvent to
induce asphaltene separation or is passed to SRU (10), or to an another SRU,
for treatment in the
same way as the diluted bitumen component (6). The ratio of solvent: bitumen
in diluted bitumen
component (20) may be, for instance, 1.4 to 30:1, or about 20:1 in the
configuration shown in Fig
1. Alternatively, diluted bitumen component (20) may be partially passed to
FSU (4) and partially
passed to SRU (10), or to another SRU. Solvent (12) from SRU 10 may be
combined with the
diluted tailing stream (8) into FSU (18), shown as stream (22), or returned to
a solvent storage tank
(not shown) from where it is recycled to make the diluted bitumen froth stream
(2), Thus, streams
(20) and (22) show recycling. In the art, solvent or diluted froth recycling
steps are known such as
described in Canadian Patent No. 2,021,185.

[0033] The froth treatment tailings (8) or tailings component (24) (with a
composition
similar to underflow stream (8) but having less bitumen and solvent), is
combined with dilution
water (25) to form diluted tailings component (26) and is sent to TSRU (16).
The dilution water
-9-


CA 02614669 2008-04-29

may be at about 70 C to about 95 C, or about 90 C and the addition rate may
vary between 0.5 to
2.0 times the mass of the tailings stream (8) or (24). Diluted tailings
component (26) may be
pumped from the FSU (18) or FSU (4) (for a single stage FSU configuration) to
TSRU (16) at the
same temperature and pressure in FSU (18) or FSU (4), as the case may be. A
backpressure control
valve may be used before an inlet into TSRU (16) to prevent solvent flashing
prematurely in the
transfer line between FSU (18) and TSRU (16). The operation of TSRU (16) is
discussed in more
detail below.

[0034] Flashed solvent vapor and steam (together 27) is sent from TSRU (16) to
a
condenser (28) for condensing both water (30) and solvent (32). Recovered
solvent (32) may be
reused in bitumen froth treatment. Tailings component (34) may be sent
directly from TSRU (16)
to a tailings storage area for future reclamation or, as shown in Figure 1,
may be sent to TSRU
(36). Tailings component (34) contains mainly water, asphaltenes, mineral
matter, and small
amount of solvent as well as unrecovered bitumen. Solvent vapor and steam
(together 38) are sent
from TSRU (36) to a condenser (40). Water (42) and solvent are condensed in
the condenser (40)
resulting in recovered solvent (44). As with recovered solvent (32), recovered
solvent (44) may be
reused in the same manner as stream (32). Tailings (47) from TSRU (36) may be
further treated or
may be sent to a tailings storage area for future reclamation.

[0035] TSRU (16) and TSRU (36) will now be discussed in further detail. TSRU
(16) is a
flash vessel or drum maintained at an absolute pressure of about 100 to about
200 kPa (or about
120 to about 170 kPa, or about 140 kPa). This TSRU may be operated at a
temperature of about
75 C to about 100 C, and has internals 46. In Figure 1, the internals (46) are
illustrated as a
plurality of interior, vertically spaced shed decks. Internals (46) (and
internals (50) described
below) may alternatively be trays, packing, baffles or other such internals
known in the art. The
diluted tailings component (26) is distributed over the internals (46) to
increase the surface area of
the diluted tailings component (26). Below the internals (46) is a ring (not
shown) having a
plurality of openings for the release of inert gas or steam (48). The inert
gas or steam (48) counter
currently contacts the downward flowing diluted tailings component (26)
distributed over the
internals (46) and provide both the necessary heat for vaporizing the solvent
and a driving force for
the vaporized solvent to the vapor phase. The internals (46) ensure that the
diluted tailings stream
is spread relatively unifornly over a large surface area that can be
subsequently exposed to inert
gas or steam. A distributor (not shown), having a plurality of openings, may
be used to evenly
distribute diluted tailings component (26) over the internals (46). The,
surface of the internals (46)
may be covered with a suitable coating, such as an asphaltene fouling
resistant coating, to mitigate
or eliminate fouling and plugging.

-10-


CA 02614669 2008-04-29

[0036] An inert gas or steam (48) is introduced below the internals (46), and
above a
tailings liquids pool in the bottom of TSRU (16), so that it flows counter
currently diluted tailings
component (26) and heats diluted tailings component (26) to vaporize the
paraffinic solvent and
some water. The mass of inert gas or steam addition rate may vary between I to
10 times the mass
of the solvent depleted tailings flow from TSRU (16). Vaporized solvent and
steam (together 27) is
removed from the TSRU (16) as discussed above.

[0037] As the solvent depleted slurry leaves the last layer of internals (46),
it is collected
in a conical section of TSRU (16) to allow for pumping from the bottom of TSRU
(16) at a steady
flow rate to either a final disposal area or to TSRU (36) for additional
solvent recovery. The
conical arrangement creates a pool of liquid slurry. The slurry is removed
from the TSRU, as
tailings component (34), using a pump in a conventional manner to the final
disposal area or
TSRU (36). Tailings component (34) may have about the same composition of
diluted tailings
component (26) minus the solvent recovered (32).

[0038] TSRU (36) operates in generally the same manner as TSRU (16) but is
maintained
at an absolute pressure of about 20 to about 200 kPa (or about 35 to about 125
kPa, or about 35 to
about 100 kPa, or about 50 kPa). The operating pressure of TSRU (36) is lower
than the pressure
of TSRU (16). That is, TSRU (36) may be operated below atmospheric pressure.
TSRU (36) may
be operated at about 75 C to about 100 C, or about 82 C to about 90 C, or
about 85 C to about
90 C, or about 90 C. Because TSRU (36) may be operated at lower pressures and
at below
atmospheric pressure, TSRU (36) may be operated at lower temperatures, for
instance about 65 C
to about 80 C, or about 70 C. As with TSRU (16), the internals (50) of TSRU
(36) are illustrated
as a plurality of interior, vertically spaced shed decks. Inert gas or steam
(52) may be introduced
below the internals (50), and above a tailings pool in the bottom of TSRU
(36).

[0039] A third TSRU could also be used in series and, in each subsequent
stage, the
operating pressure may be lower than the previous one to achieve additional
solvent recovery. In
fact, more than three TSRU's could be used.

[0040] In one embodiment, one, two, or more than two TSRU's are used where the
froth
treatment tailings solvent recovery is effected in the absence of "mechanical
means used to
substantially break up asphaltene agglomerates or to prevent the agglomeration
of asphaltene".
The term "agglomerates" as used herein is not limited by shape and includes
flocs and aggregates.
The term "substantially" is used here to exclude means that does not, to a
substantial extent,
mechanically break up asphaltene agglomerates or prevent the agglomeration of
asphaltene. Non-
limiting examples of "mechanical means used to substantially break up
asphaltene agglomerates or
to prevent the agglomeration of asphaltene" are the agitation means described
Canadian Patent No.
-11-


CA 02614669 2008-04-29

2,353,109 where the tailings pool is agitated to the point where the
asphaltenes are dispersed,
submerged and prevented from re-agglomerating and the solids are maintained in
suspension. In
that patent, agitation may be effected by a mechanical impeller, or an
altemate agitation means,
such as a pump-around circuit to pump the slurry from the top of the liquid
pool to the lower part
of the liquid pool or vice versa. Another non-limiting example of such means
are the shearing
conditions provided by pumps, mixers or other apparatuses, described in
Canadian Patent
Application No. 2,454,942, which are said to be preferably provided in the
recycle circuit first, to
break up asphaltene flocs/aggregates and second, to enhance recovery of
solvent from the tailings.
The "mechanical means used to substantially break up asphaltene agglomerates
or to prevent the
agglomeration of asphaltene" does not include means, the purpose of which is
unrelated to
breaking up asphaltene agglomerates or to preventing agglomeration of
asphaltenes, such as a
pump disposed before or after the TSRU as shown herein.

[0041] Water may be recovered from the solvent depleted tailings stream (34 or
47)
downstream of the slurry pump and may be recycled for re-use upstream of the
tailing solvent
recovery unit in order to recover valuable heat contained in the water, thus
reducing the energy
requirements of the process. For example, recovered water may be combined with
the dilution
water (25) upstream of the tailings solvent recovery unit but this is not to
provide additional
agitation to the unit.

[0042] Example 1

[0043] In a small scale pilot test, a run was operated at about atmospheric
pressure
without shearing or agitation in or around TSRU (16) with internals (46) and
successfully resulted
in solvent loss of less than 2.8 bbl per thousand barrels of bitumen product
(6). The addition of
steam resulted in a further reduction to less than 1.0 bbl of solvent loss per
thousand barrels of
bitumen product. A typical TSRU (16) tailings (34) sample was then subjected
laboratory scale
vacuum separation tests to simulate the performance of the second stage TSRU
(36). These results
are shown in Table 1.

[0044] Table 1: Solvent Recovery Performance

Pressure Average solvent Solvent Loss (bbl /
(atm.abs) content (wt%) 1000bbls of bitumen)
1.00 0.028 1.18
0.79 0.024 0.97
0.59 0.015 0.63

-12-


CA 02614669 2007-11-30

[0045] Pumps are used to maintain a specified level in each TSRU and the
vessels are
sized to maintain a high downward velocity of the slurry.

[0046] As discussed herein, it has been discovered that recovery of solvent
from
asphaltene agglomerates in a TSRU is effective without agitation in or around
the TSRU. Thus,
mechanical means used to substantially physically break up asphaltene
agglomerates or to prevent
the agglomeration of asphaltene may be omitted. In addition to the embodiments
discussed herein
using internals, in another embodiment, there is provided a process for
recovering paraffinic
solvent from froth treatment tailings produced in the treatment of bitumen
froth comprising:
introducing the froth treatment tailings into a tailings solvent recovery unit
(TSRU) (which may or
may not have internals); introducing inert gas or steam into a liquid pool
formed in the bottom of
the TSRU to vaporize at least a portion of the paraffinic solvent; and
removing the vaporized
solvent from the TSRU; wherein the froth treatment tailings contain
asphaltenes; and wherein the
at least a portion of the solvent is vaporized from asphaltene agglomerates.
In one embodiment,
the process is effected in the absence of mechanical means used to
substantially physically break
up asphaltene agglomerates or to prevent the agglomeration of asphaltene.

[0047] The phrase "to vaporize at least a portion of the paraffinic solvent"
is used herein
to make clear that not all of the solvent is necessarily vaporized. In certain
embodiments, the
percentage, by volume, of solvent that is vaporized is: at least 70%, at least
80%, at least 90%, at
least 95%, at least 98%, at least 99%, at least 99.5%, at least 99.9%, or at
least 99.9%.

[0048] In the preceding description, for purposes of explanation, numerous
details are set
forth in order to provide a thorough understanding of the embodiments of the
invention. However,
it will be apparent to one skilled in the art that these specific details are
not required in order to
practice the invention

[0049] The above-described embodiments of the invention are intended to be
examples
only. Alterations, modifications and variations can be effected to the
particular embodiments by
those of skill in the art without departing from the scope of the invention,
which is defined solely
by the claims appended hereto.

-13-

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

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Administrative Status

Title Date
Forecasted Issue Date 2008-12-30
(22) Filed 2007-05-03
(41) Open to Public Inspection 2007-09-30
Examination Requested 2007-11-30
(45) Issued 2008-12-30

Abandonment History

There is no abandonment history.

Maintenance Fee

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Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Advance an application for a patent out of its routine order $500.00 2007-11-30
Request for Examination $800.00 2007-11-30
Application Fee $400.00 2007-11-30
Final Fee $300.00 2008-10-07
Maintenance Fee - Patent - New Act 2 2009-05-04 $100.00 2009-04-07
Maintenance Fee - Patent - New Act 3 2010-05-03 $100.00 2010-04-07
Maintenance Fee - Patent - New Act 4 2011-05-03 $100.00 2011-04-18
Maintenance Fee - Patent - New Act 5 2012-05-03 $200.00 2012-04-16
Maintenance Fee - Patent - New Act 6 2013-05-03 $200.00 2013-04-15
Maintenance Fee - Patent - New Act 7 2014-05-05 $200.00 2014-04-15
Maintenance Fee - Patent - New Act 8 2015-05-04 $200.00 2015-04-13
Maintenance Fee - Patent - New Act 9 2016-05-03 $200.00 2016-04-12
Maintenance Fee - Patent - New Act 10 2017-05-03 $250.00 2017-04-13
Maintenance Fee - Patent - New Act 11 2018-05-03 $250.00 2018-04-12
Maintenance Fee - Patent - New Act 12 2019-05-03 $250.00 2019-04-15
Maintenance Fee - Patent - New Act 13 2020-05-04 $250.00 2020-04-21
Maintenance Fee - Patent - New Act 14 2021-05-03 $255.00 2021-04-13
Maintenance Fee - Patent - New Act 15 2022-05-03 $458.08 2022-04-20
Maintenance Fee - Patent - New Act 16 2023-05-03 $473.65 2023-04-19
Maintenance Fee - Patent - New Act 17 2024-05-03 $473.65 2023-11-17
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
IMPERIAL OIL RESOURCES LIMITED
Past Owners on Record
SURY, KEN
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Cover Page 2008-02-28 2 49
Representative Drawing 2008-12-08 1 11
Cover Page 2008-12-08 2 49
Abstract 2007-11-30 1 20
Description 2007-11-30 13 809
Claims 2007-11-30 2 55
Drawings 2007-11-30 1 16
Representative Drawing 2008-02-06 1 10
Description 2008-04-29 13 813
Claims 2008-04-29 2 54
Drawings 2008-04-29 1 15
Correspondence 2008-01-30 1 26
Correspondence 2007-01-31 1 37
Assignment 2007-11-30 2 86
Prosecution-Amendment 2008-02-06 1 14
Prosecution-Amendment 2008-02-21 2 83
Correspondence 2008-02-12 2 65
Prosecution-Amendment 2008-04-29 10 422
Assignment 2007-11-30 4 150
Correspondence 2008-10-07 1 36