U.S. patent application number 14/268918 was filed with the patent office on 2015-11-05 for demulsifier injection system for froth treatment product quality enhancement.
This patent application is currently assigned to SYNCRUDE CANADA LTD. in trust for the owners of the syncrude Project, as such owners exist now and. The applicant listed for this patent is SYNCRUDE CANADA LTD. in trust for the owners of the syncrude Project, as such owners exist now and. Invention is credited to SUJIT BHATTACHARYA, YONG GU, BRIAN KNAPPER, YIN MING SAMSON NG.
Application Number | 20150315477 14/268918 |
Document ID | / |
Family ID | 54354793 |
Filed Date | 2015-11-05 |
United States Patent
Application |
20150315477 |
Kind Code |
A1 |
NG; YIN MING SAMSON ; et
al. |
November 5, 2015 |
DEMULSIFIER INJECTION SYSTEM FOR FROTH TREATMENT PRODUCT QUALITY
ENHANCEMENT
Abstract
A method of improving the quality of diluted bitumen product in
a bitumen froth treatment process is provided comprising: adding a
demulsifier to bitumen froth to produce a mixture of bitumen froth
and demulsifier, wherein the demulsifier is added at a dosage
sufficient to reduce bitumen water content in the diluted bitumen
product; subjecting the mixture of bitumen froth and demulsifier to
a mixing energy input of greater than about 100 J/kg; adding a
hydrocarbon diluent to the mixed mixture of bitumen froth and
demulsifier to produce a diluent diluted bitumen froth; and
subjecting the diluent diluted bitumen froth to a separation
process to produce the diluted bitumen product. In one embodiment,
demulsifier is first added to naphtha to form a demulsifier-diluent
mixture which is then added to bitumen froth to form a diluted
bitumen froth prior to subjecting the diluted bitumen froth to a
mixing energy input of greater than about 100 J/kg.
Inventors: |
NG; YIN MING SAMSON;
(Sherwood Park, CA) ; KNAPPER; BRIAN; (Edmonton,
CA) ; BHATTACHARYA; SUJIT; (Edmonton, CA) ;
GU; YONG; (Edmonton, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SYNCRUDE CANADA LTD. in trust for the owners of the syncrude
Project, as such owners exist now and |
Fort McMurrey |
|
CA |
|
|
Assignee: |
SYNCRUDE CANADA LTD. in trust for
the owners of the syncrude Project, as such owners exist now
and
Fort McMurray
CA
|
Family ID: |
54354793 |
Appl. No.: |
14/268918 |
Filed: |
May 2, 2014 |
Current U.S.
Class: |
208/390 |
Current CPC
Class: |
C10G 33/04 20130101;
C10G 1/04 20130101; C10G 1/002 20130101 |
International
Class: |
C10G 1/00 20060101
C10G001/00 |
Claims
1. A method of improving the quality of diluted bitumen product in
a bitumen froth treatment process comprising: adding a demulsifier
to bitumen froth to produce a mixture of bitumen froth and
demulsifier, wherein the demulsifier is added at a dosage
sufficient to reduce water content in the diluted bitumen product;
subjecting the mixture of bitumen froth and demulsifier to a mixing
energy input of greater than about 100 J/kg; adding a hydrocarbon
diluent to the mixed mixture of bitumen froth and demulsifier to
produce a diluent diluted bitumen froth; and subjecting the diluent
diluted bitumen froth to a separation process to produce the
diluted bitumen product.
2. The method of claim 1, wherein the active chemical concentration
of the demulsifier is about 35%.
3. The method of claim 2, wherein the dosage of the demulsifier
ranges from about 1 ppm to about 50 ppm.
4. The method of claim 1, wherein the demulsifier comprises a
polyglycol, a polyglycol ester, an ethoxylated alcohol or amine, an
ethoxylated resin, an ethoxylated phenol formaldehyde resin, an
ethoxylated nonylphenol, a polyhydric alcohol, ethylene oxide, a
propylene oxide block copolymer fatty acid, a fatty alcohol, a
fatty amine, a quaternary, or a sulfonic acid salt.
5. The method of claim 1, wherein mixing energy input is provided
by adding the demulsifier to the bitumen froth at a suction side of
a pump.
6. The method of claim 1, wherein mixing energy input is about 300
J/kg.
7. The method of claim 1, wherein the diluted bitumen water content
is less than about 5 wt %.
8. The method of claim 1, wherein the hydrocarbon diluent is
naphtha.
9. The method of claim 8, wherein naphtha is added in an amount
such that the naphtha to bitumen ratio of the diluent diluted
bitumen froth is in the range of about 0.5 to about 1.0.
10. The method of claim 9, wherein naphtha is added in an amount
such that the naphtha to bitumen ratio of the diluent diluted
bitumen froth is about 0.7.
11. The method of claim 1, wherein the separation process involves
the use of at least one gravity settler, at least one centrifuge,
at least one filtration system or a combination thereof.
12. The method of claim 1, wherein the separation process involves
the use of a series of centrifuges.
13. The method of claim 12, wherein at least one centrifuge in
series is a scroll centrifuge and at least one centrifuge in series
is a disc centrifuge.
14. The method of claim 1, wherein the separation process involves
the use of at least one gravity separator.
15. The method of claim 14, wherein the at least one gravity
separator is an inclined plate settler.
16. A method of improving the quality of diluted bitumen product in
a bitumen froth treatment process, comprising: adding a demulsifier
to a hydrocarbon diluent to form a demulsifier-diluent mixture;
adding the demulsifier-diluent mixture to bitumen froth to produce
a diluted bitumen froth and subjecting the diluted bitumen froth to
a mixing energy input of greater than about 100 J/kg; and
subjecting the mixed diluted bitumen froth to a separation process
to produce the diluted bitumen product.
17. The method of claim 16, wherein the active chemical
concentration of the demulsifier is about 35%.
18. The method of claim 17, wherein the dosage of the demulsifier
ranges from about 1 ppm to about 50 ppm.
19. The method of claim 16, wherein the demulsifier comprises a
polyglycol, a polyglycol ester, an ethoxylated alcohol or amine, an
ethoxylated resin, an ethoxylated phenol formaldehyde resin, an
ethoxylated nonylphenol, a polyhydric alcohol, ethylene oxide, a
propylene oxide block copolymer fatty acid, a fatty alcohol, a
fatty amine, a quaternary, or a sulfonic acid salt.
20. The method of claim 16, wherein mixing energy input is provided
by adding the demulsifier-diluent mixture to the bitumen froth at a
suction side of a pump.
21. The method of claim 16, wherein mixing energy input is about
300 J/kg.
22. The method of claim 16, wherein the diluted bitumen water
content is less than about 5 wt %.
23. The method of claim 16, wherein the hydrocarbon diluent is
naphtha.
24. The method of claim 23, wherein the naphtha concentration in
the demulsifier-diluent mixture is such that the naphtha to bitumen
ratio of the diluted bitumen froth is in the range of about 0.5 to
about 1.0.
25. The method of claim 24, wherein naphtha concentration in the
demulsifier-diluent mixture is such that the naphtha to bitumen
ratio of the diluted bitumen froth is about 0.7.
26. The method of claim 16, wherein the separation process involves
the use of at least one gravity settler, at least one centrifuge,
at least one filter or a combination thereof.
27. The method of claim 16, wherein the separation process involves
the use of a series of centrifuges.
28. The method of claim 27, wherein at least one centrifuge in
series is a scroll centrifuge and at least one centrifuge in series
is a disc centrifuge.
29. The method of claim 16, wherein the separation process involves
the use of at least one gravity separator.
30. The method of claim 29, wherein the at least one gravity
separator is an inclined plate settler.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a method of
improving the quality of diluted bitumen product through better
mixing by adding demulsifier at a specific treatment location and
dosage in a gravity-based or centrifuge-based bitumen froth
treatment process.
BACKGROUND OF THE INVENTION
[0002] Oil sand deposits such as those found in the Athabasca
Region of Alberta, Canada, generally comprise water-wet sand grains
held together by a matrix of viscous heavy oil or bitumen. Bitumen
is a complex and viscous mixture of large or heavy hydrocarbon
molecules which contain a significant amount of sulfur, nitrogen
and oxygen. Oil sands processing involves extraction of bitumen as
froth and bitumen froth treatment to produce diluted bitumen which
is further processed to produce synthetic crude oil and other
valuable commodities.
[0003] Extraction is typically conducted by mixing the oil sand in
hot/warm water and aerating the resultant slurry to promote the
attachment of bitumen to air bubbles, creating a lower-density
bitumen froth which floats and can be recovered in a primary
separation vessel or "PSV" (generally referred to as primary
bitumen froth). Sand grains sink and are concentrated in the bottom
of the PSV. They leave the bottom of the vessel as a wet tailings
stream containing a small amount of bitumen. Middlings, a watery
mixture containing fine solids and bitumen, extend between the
froth and sand layers. The wet tailings and middlings are
separately withdrawn, combined and sent to a secondary flotation
process. This secondary flotation process is commonly carried out
in a deep cone vessel (a "TOR" vessel) wherein air is sparged into
the vessel to assist with flotation. The bitumen recovered by
flotation in the TOR vessel is generally recycled to the PSV. The
middlings from the deep cone vessel are further processed in
induced air flotation cells to recover contained bitumen as
secondary bitumen froth.
[0004] Froth treatment is the process of reducing water and solids
contents from the bitumen froths produced by the PSV and other
secondary flotation processes to produce a clean bitumen product
(i.e., "diluted bitumen") for downstream upgrading processes. It
has been conventional to dilute this bitumen froth with a light
hydrocarbon diluent, for example, with naphtha, to increase the
difference in specific gravity between the bitumen and water and to
reduce the bitumen viscosity, to thereby aid in the separation of
the water and solids from the bitumen. This diluent diluted bitumen
froth is commonly referred to as "dilfroth." It is desirable to
"clean" dilfroth, as both the water and solids pose fouling and
corrosion problems in upgrading refineries. By way of example, the
composition of naphtha-diluted bitumen froth typically might have a
naphtha/bitumen ratio of 0.65 and contain 20% water and 7% solids.
It is desirable to reduce the water and solids content to below
about 3% and about 1%, respectively.
[0005] Separation of the bitumen from water and solids may be done
by treating the dilfroth in a series of scroll and/or disc
centrifuges. Alternatively, the dilfroth may be subjected to
gravity separation in a series of inclined plate separators ("IPS")
in conjunction with countercurrent solvent extraction using added
light hydrocarbon diluent. However, these treatment processes still
result in bitumen product often containing undesirable amounts of
solids and water. Product solids lead to increased wear of
downstream equipment, higher maintenance costs, and unplanned
capacity losses and outages. Since the contents of the product
solids and water are related, reducing water is a means of removing
solids. Chemical demulsification is an effective means of reducing
product water (and hence also product solids) from diluted
bitumen.
[0006] In a gravity-based process, demulsifier is generally added
after naphtha is injected into bitumen froth prior to transport to
the IPS. The dosage of demulsifier is generally constant at about
35 ppm. However, it was observed that increasing the dosage from 35
to 50 ppm does not impact the product water content. In a
centrifuge-based process, an increase in demulsifier dosage also
has no impact on product water content. An inline mixer may be
added to improve the mixing of the demulsifier and dilfroth,
however, it was hypothesized that better demulsifier mixing may
still be required.
[0007] Accordingly, there is a need to develop a better mixing
method for enhancing the demulsifier performance to improve the
quality of diluted bitumen product in bitumen froth treatment
processes.
SUMMARY OF THE INVENTION
[0008] The current application is directed to a method of improving
the quality of diluted bitumen product (i.e., reducing the water
and solids content) by adding demulsifier at a specific treatment
location and dosage in a gravity- or centrifuge-based bitumen froth
treatment process. It was surprisingly discovered that by
conducting the method of the present invention, one or more of the
following benefits may be realized:
[0009] (1) The effectiveness of demulsifier to reduce diluted
bitumen water content is significantly enhanced by sufficient
mixing.
[0010] (2) With sufficient mixing, demulsifier is more effective in
reducing diluted bitumen water content when added directly to
naphtha or froth rather than to diluted froth.
[0011] (3) In a gravity-based process, sufficient mixing occurs
when demulsifier is added to the froth just prior to the froth
entering a pumping apparatus which is used to transport the bitumen
froth (i.e., at the suction or inlet side of a froth pump).
[0012] (4) In a centrifuge-based process, sufficient mixing occurs
when demulsifier is added to the froth at the suction of froth feed
pump.
[0013] (5) At the suction side of the froth feed pump, the energy
input is on the order of 300 J/kg which is an order of magnitude
higher than the energy input at conventional locations where
demulsifier is typically injected. This level of energy input is
found to be effective to enhance the demulsifier performance.
Addition of demulsifier at the pump suction is optimal for mixing
and does not require any capital investment on mixing
equipment.
[0014] (6) Increasing the dosage of demulsifier further decreases
the diluted bitumen water content.
[0015] Use of the present invention improves the performance of
demulsifier to reduce bitumen water and solids content, thereby in
turn improving bitumen product (i.e., diluted bitumen or "dilbit")
quality. Reduction of solids content minimizes wear of downstream
equipment, maintenance costs, and unplanned capacity losses and
outages.
[0016] Thus, broadly stated, in one aspect of the invention, a
method of improving the quality of diluted bitumen product in a
bitumen froth treatment process is provided, comprising: [0017]
adding demulsifier to bitumen froth to produce a mixture of bitumen
froth and demulsifier, wherein demulsifier is added at a dosage
sufficient to reduce bitumen water content in the diluted bitumen
product; [0018] subjecting the mixture of bitumen froth and
demulsifier to a mixing energy input of greater than about 100
J/kg; [0019] adding a hydrocarbon diluent to the sufficiently mixed
mixture of bitumen froth and demulsifier to produce a diluent
diluted bitumen froth; and [0020] subjecting the diluent diluted
bitumen froth to a separation process to produce the diluted
bitumen product.
[0021] In one embodiment, the separation process involves the use
of at least one gravity settler, at least one centrifuge, at least
one filter, or any combination thereof. In one embodiment, the
energy input is between about 200 J/kg to about 350 J/kg. In one
embodiment, the dosage of demulsifier ranges up to about 50 ppm. In
one embodiment, the demulsifier content is in the range of about 1
ppm to about 50 ppm. In one embodiment, the mixing energy is
provided by adding the demulsifier to the bitumen froth at a
suction side of a pump.
[0022] In another aspect of the invention, a method of improving
the quality of diluted bitumen product in a bitumen froth treatment
process is provided, comprising: [0023] adding a demulsifier to a
hydrocarbon diluent to form a demulsifier-diluent mixture; [0024]
adding the demulsifier-diluent mixture to bitumen froth to produce
a diluted bitumen froth and subjecting the diluted bitumen froth to
a mixing energy input of greater than about 100 J/kg; and [0025]
subjecting the mixed diluted bitumen froth to a separation process
to produce the diluted bitumen product.
[0026] In one embodiment, the separation process involves the use
of at least one gravity settler, at least one centrifuge, at least
one filter, or any combination thereof. in one embodiment, the
energy input is between about 200 J/kg to about 350 J/kg. In one
embodiment, the amount of demulsifier-diluent mixture added to
bitumen froth results in the diluted bitumen froth having a naphtha
to bitumen ratio of about 0.5 to about 1.0 and a demulsifier
content of up to about 50 ppm. In one embodiment, the demulsifier
content is in the range of about 1 ppm to about 50 ppm. In one
embodiment, the mixing energy is provided by adding the demulsifier
to the bitumen froth at a suction side of a pump.
DESCRIPTION OF THE DRAWINGS
[0027] Referring to the drawings wherein like reference numerals
indicate similar parts throughout the several views, several
aspects of the present invention are illustrated by way of example,
and not by way of limitation, in detail in the figures,
wherein:
[0028] FIG. 1 is a diagram showing, in general, a prior art froth
treatment process.
[0029] FIG. 2 is a diagram showing, in general, one embodiment of a
froth treatment process of the present invention.
[0030] FIG. 3 is a diagram showing, in general, another embodiment
of a froth treatment process of the present invention.
[0031] FIG. 4 is a graph showing the effect of improved mixing on
diluted bitumen water content (%) over settling time (min).
[0032] FIG. 5 is a graph showing the effect of adding demulsifier
to diluted froth, naphtha, and froth with sufficient mixing on
diluted bitumen water content (%) over settling time (min).
[0033] FIG. 6 is a diagram showing the demulsifier addition to the
suction of froth feed pump feeding IPS.
[0034] FIG. 7 is a graph showing the effect of adding demulsifier
(20 ppm) to froth at the suction side of the froth pump versus
addition to naphtha diluted froth after the froth pump (base case
or prior art) on diluted bitumen water content for IPS unit.
[0035] FIG. 8 is a graph showing the effect of adding demulsifier
(50 ppm) to froth at the suction side of the froth pump versus
addition to naphtha diluted froth after the froth pump (base case
or prior art) on diluted bitumen water content for IPS unit.
[0036] FIG. 9 is a diagram showing the demulsifier addition to the
suction of froth feed pump feeding the centrifuges.
[0037] FIG. 10 is a graph showing the effect of adding different
demulsifier dosages (20 and 35 ppm) to froth on diluted bitumen
water content for centrifuge unit.
[0038] FIG. 11 is a graph showing the effect of adding demulsifier
(50 ppm) to froth at the suction side of the froth pump versus
addition to naphtha diluted froth after the froth pump (base case
or prior art) on diluted bitumen water content for centrifuge
unit.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0039] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
embodiments of the present invention and is not intended to
represent the only embodiments contemplated by the inventor. The
detailed description includes specific details for the purpose of
providing a comprehensive understanding of the present invention.
However, it will be apparent to those skilled in the art that the
present invention may be practiced without these specific
details.
[0040] The present invention relates generally to a method of
improving the quality of diluted bitumen product by adding
demulsifier at a specific treatment location and dosage in a
gravity- or centrifuge-based froth treatment process.
Demulsification is an effective means of removing water from
diluted bitumen. As used herein, the term "demulsifier" refers to
an agent which breaks emulsions or causes water droplets either to
coalesce and settle, or to flocculate and settle in flocs.
Demulsifiers are commonly formulated from the following types of
chemistries: polyglycols and polyglycol esters, ethoxylated
alcohols and amines, ethoxylated resin, ethoxylated phenol
formaldehyde resins, ethoxylated nonylphenols, polyhydric alcohols,
ethylene oxide, propylene oxide block copolymer fatty acids, fatty
alcohols, fatty amine and quaternaries and sulfonic acid salts.
[0041] FIG. 1 is a general schematic of a conventional
gravity-based froth treatment process using gravity settlers. As
used herein, the term "gravity-based" process refers to an
operation in which diluted bitumen is separated from water and
solids using gravity, and is therefore distinguished from other
separation operations such as molecular sieve processes, absorption
processes, adsorption processes, magnetic processes, electrical
processes, and the like. As used herein, the term "gravity settler"
refers to any suitable apparatus which facilitates gravity settling
including, but not limited to, a gravity settling vessel and an
inclined plate separator ("IPS"). As used herein, the term "IPS"
refers to an apparatus comprising a plurality of stacked inclined
plates onto which a mixture to be separated may be introduced so
that the mixture passes along the plates in order to achieve
separation of components of the mixture.
[0042] Bitumen froth 10 is initially received from an extraction
facility which extracts bitumen from oil sand using a water
extraction process known in the art. The bitumen froth 10, as
received, typically comprises about 60% bitumen, about 30% water
and about 10% solids. The bitumen froth 10 is pumped via froth pump
12 into line 14. A hydrocarbon diluent 16 is mixed with bitumen
froth 10 as it moves through line 14 to provide diluent-diluted
bitumen froth (dilfroth). In one embodiment, the hydrocarbon
diluent 16 is naphtha (N). The naphtha is supplied in an amount
such that the naphtha to bitumen ratio of the dilfroth is
preferably in the range of 0.5 to 1.0, most preferably about
0.7.
[0043] Demulsifier (D) 18 is then added to the dilfroth as it
continues to move through line 14 towards the inclined plate
settler ("IPS") 20. Demulsifier 18 is typically added at a dosage
of about 35 ppm. The dilfroth and demulsifier can be mixed using an
inline mixer 22 prior to feeding the dilfroth to inclined plate
settler 20. As an example, with the inline mixer 22 bypassed,
energy input for mixing is about 20 J/kg. With the inline mixer 22
online, the energy input increases to about 50 J/kg. However, it
was discovered that an energy input of 50 J/kg was not sufficient
and that the energy input required for adequate mixing of
demulsifier with froth feed should be greater than 100 J/kg,
preferably on the order of about 300 J/kg.
[0044] FIG. 2 is a general schematic of one embodiment of a froth
treatment process of the present invention using gravity settlers.
It is understood, however, that centrifuges can replace gravity
settlers. As used herein, the term "centrifuge-based" process
refers to an operation in which bitumen is separated from water and
solids using centrifugal acceleration or centripetal acceleration
resulting from rotational movement of a suitable apparatus
including, but not limited to, a scroll centrifuge, disc
centrifuge, hydrocyclone, propelled vortex separator, and the
like.
[0045] Having discovered that a mixing energy of 50 J/kg was not
sufficient, it was determined that demulsifier (D) 18 could be
added at the suction side of the froth pump 12 to mix with the
bitumen froth 10 as it is pumped via the froth pump 12 into line
14. Adding demulsifier 18 to the froth 10 and then pumping the
mixture through froth pump 12 resulted in about 250 J/kg of mixing
energy. In one embodiment, the concentration of demulsifier was
about 35% based on active ingredient. A sufficient amount of
demulsifier is added to yield the desired dosage. In one
embodiment, the dosage of demulsifier ranges up to about 50
ppm.
[0046] A hydrocarbon diluent 16 is then added to the mixture of
bitumen froth 10 and demulsifier 18 as it moves through line 14 to
provide diluent-diluted bitumen froth-demulsifier. In one
embodiment, the hydrocarbon diluent 16 is naphtha (N). The
diluent-diluted bitumen froth-demulsifier may then bypass or,
optionally, pass through the inline mixer 22 for additional mixing
before being subjected to separation in the gravity settler 20. In
one embodiment, the gravity settler 20 is an IPS. In one case, when
demulsifier 18 is added at the suction side of the froth pump 12,
the energy input for mixing is about 250 J/kg with the inline mixer
bypassed and about 280 J/kg with the inline mixer online. The
energy input thus approximates 300 J/kg which results in sufficient
mixing of bitumen froth 10 and demulsifier 18. With proper mixing,
demulsifier is more effective in reducing diluted bitumen water
content. In one embodiment, the diluted bitumen water content is
less than about 5 wt %.
[0047] FIG. 3 is a general schematic of another embodiment of a
froth treatment process of the present invention using gravity
settlers. It is understood, however, that alternatives such as
centrifugation and filtration can replace gravity settlers. In this
embodiment, demulsifier (D) is added to a hydrocarbon diluent such
as naphtha (N) to give a demulsifier/diluents mixture 19 (D+N). The
demulsifier/diluent mixture 19 is then added to froth 10 at the
suction side of the froth pump 12 to mix with the bitumen froth 10
as it is pumped via the froth pump 12 into line 14. Adding
demulsifier/diluent mixture 19 to the froth 10 and then pumping the
mixture through froth pump 12 results in about 250 J/kg of mixing
energy. In one embodiment, the concentration of demulsifier was
about 35% based on active ingredient. A sufficient amount of
demulsifier is added to yield the desired dosage. In one
embodiment, the dosage of demulsifier ranges up to about 50
ppm.
[0048] The diluent-diluted bitumen froth-demulsifier may then
bypass or, optionally, pass through the inline mixer 22 for
additional mixing before being subjected to separation in the
gravity settler 20. In one embodiment, the gravity settler 20 is an
IPS. With the inline mixer online, about 280 J/kg of energy is
input.
[0049] Exemplary embodiments of the present invention are described
in the following Examples, which are set forth to aid in the
understanding of the invention, and should not be construed to
limit in any way the scope of the invention as defined in the
claims which follow thereafter.
Example 1
[0050] Batch tests were conducted to determine whether ineffective
demulsifier performance in the prior art froth treatment operation
may be caused by inadequate mixing of the demulsifier into the
naphtha diluted froth. A shaker table was used to simulate the
energy input of the existing system (prior art) shown in FIG. 1. As
can be seen in FIG. 4, when lower mixing energy is used, after 60
minutes settling time, the diluted bitumen water content was about
1.5%. An impeller and baffles were used to simulate a higher energy
input for mixing other than pipe mixing. Improved mixing enhanced
the effectiveness of demulsifier as indicated by the decrease in
diluted bitumen water content, i.e., after 60 minutes settling
time, the water content in the diluted bitumen was reduced to about
1.0%.
[0051] FIG. 5 shows that, with sufficient mixing, demulsifier was
even more effective in decreasing diluted bitumen water content
when added to naphtha or froth rather than to diluted froth. The
results suggest that both sufficient mixing and the location of
demulsifier addition are significant.
Example 2
[0052] Based on the results obtained in Example 1, a field
demonstration was initiated using a gravity-based process (i.e., an
inclined plate settler unit). The test system is shown in FIG. 6.
Froth tank 200 fed froth 210 via line 211 to froth pump 212.
Demulsifier 218 was added to the suction side of the froth pump 212
via line 217. This location provides sufficient mixing energy
without significant changes to the operating system. A conservative
estimate of the mixing energy input is around 250 J/kg with the
inline mixer bypassed and about 30 J/kg higher with an inline mixer
online, as shown in FIG. 2. This energy input is an order of
magnitude higher than that of the original location of demulsifier
addition (prior art). For comparison, in some runs, demulsifier was
added at the original location shown in FIG. 1, i.e., after the
froth pump.
[0053] Demulsifier 218 was shipped in totes 234 and provided a 35
wt % active injection concentrations (Emulsotron product #X2105,
NALCO Champion An EcoLab Company). A progressive cavity chemical
pump 230 maintained stable flow. A variable frequency drive (VFD)
controller 232 installed on the pump skid controlled the pump
speed. Using a VFD controller 232 and flowmeter 236, the
demulsifier flow rate was set at a desired level to achieve a
target dosage. The flowmeter 236 was calibrated to ensure stability
and accuracy of the demulsifier flow rate. The measured froth flow
rate was used to determine the demulsifier flow rate based on the
target dosage. A pressure relief valve 238 was installed on the
pump discharge line to open and divert flow back to the pump
suction in response to overpressure. A check valve on the tied-in
location prevented froth from entering the chemical system, thereby
avoiding line plugging or contamination of the demulsifier. The
demulsifier 218 was introduced into the froth pump suction through
a 3/4'' injection quill located 31/4'' from the wall inside a 24''
froth suction pipe. The discharge end of the quill was reduced to
3/8'' and fed the demulsifier at 45.degree. in the direction of the
flow.
[0054] i) IPS ON/OFF Test at a Demulsifier Dosage of 20 ppm
[0055] An ON/OFF test was conducted to determine the effect of
adding demulsifier at an injection concentration of 35% to either
naphtha diluted froth (i.e., after the froth pump), or to froth at
the suction side of the froth pump. The diluted bitumen water
content was measured using a water cut meter at the IPS product
line. In FIG. 7, the step change shows the injection location and
the dosage is constant at 20 ppm. The high setting refers to
addition of demulsifier at the original location (prior art), and
the low setting refers to the addition of demulsifier to the froth
pump suction. The jagged line indicates the product water content.
Before start-up, the demulsifier dosage to the IPS was set to 20
ppm for more than three hours (i.e., at least three times of the
IPS residence time) and the IPS was stable. When the existing
system was shut down, the test system was started immediately.
There was a time delay between when the test system was started up
and the time that demulsifier actually arrived in the IPS. When the
test system was shut down, the original system was started up back
to a dosage of 20 ppm. FIG. 7 shows a consistent pattern over the
one hour interval of ON/OFF. When addition of the demulsifier
switched from the original location to the froth pump suction, the
water content in the IPS product dropped significantly from
.about.2.4% to .about.1.4%. When demulsifier was added at the
original location, the water content in IPS product increased. This
example demonstrated that enhanced demulsifier mixing significantly
reduced diluted bitumen product water.
[0056] ii) IPS ON/OFF Test at the Demulsifier Dosage of 50 ppm
[0057] The effect of demulsifier injection location at a dosage of
50 ppm was determined. FIG. 8 shows a similar trend of IPS product
water content when switching demulsifier addition between the
original (prior art) and test locations. Again, consistent with the
results for the demulsifier dosage of 20 ppm, the diluted bitumen
water reduction was also observed using the 50 ppm dosage through
enhanced mixing in the suction of froth feed pump. In this case,
the diluted bitumen water content significantly decreased down to
0.45%.
Example 3
[0058] A field demonstration was performed using two different
units of centrifuges. Each unit comprises a series of centrifuges.
The test system is shown in FIG. 9. Froth tank 300 feeds froth 310
via lines 311a and 311b to froth pumps 312a and 312b, respectively.
Demulsifier 318 is added to the suction side of the froth pumps
312a and 312b via lines 317a and 317b, respectively. This location
provides sufficient mixing energy without significant changes to
the operating system. Historically, when using a centrifuge-based
process, demulsifier is added after the first stage centrifuge.
[0059] As with FIG. 6, demulsifier 318 was shipped in totes 334 and
provided a 35 wt % active injection concentrations (Emulsotron
product #X2105, NALCO Champion An EcoLab Company). A progressive
cavity chemical pump 330 maintained stable flow. A variable
frequency drive (VFD) controller 332 installed on the pump skid
controlled the pump speed. Using a VFD controller 332 and flowmeter
336, the demulsifier flow rate was set at a desired level to
achieve a target dosage. The flowmeter 336 was calibrated to ensure
stability and accuracy of the demulsifier flow rate. The measured
froth flow rate was used to determine the demulsifier flow rate
based on the target dosage. A pressure relief valve 338 was
installed on the pump discharge line to open and divert flow back
to the pump suction in response to overpressure. The demulsifier
was introduced into the froth pumps 312a and 312b suctions through
a 1/4'' injection quill located 31/4'' from the wall inside a 24''
froth suction pipe. The discharge end of the quill was reduced to
3/8'' and fed the demulsifier at 45.degree. in the direction of the
flow.
[0060] i) Centrifuge Demulsifier Dosage Test
[0061] When demulsifier is added at the original location (i.e.,
after the first stage centrifuge, prior art), the product water
content does not correlate with demulsifier dosage, and a change in
demulsifier dosage does not affect product quality. The effects of
different demulsifier dosages added at the test location (i.e., the
suction side of the froth feed pumps) on product water content was
determined (FIG. 10). Demulsifier dosage was calculated based on
fresh froth feed rate. The rectangular-shaped step-change line
labeled "demulsifier" indicates the demulsifier dosage and
location. The jagged line labeled "water" indicates the product
water content of the centrifuges. Prior to 11:00, demulsifier was
added after the first stage centrifuge at a dosage of 35 ppm using
the demulsifier active injection concentration of 35 wt %. The
product water content was stable and constant before switching to
the test system. When the test system was started, there was an
initial product water content increase. This was due to the time
delay between shut-down of the original system and start-up of the
test system. The demulsifier active injection concentration
remained at 35% with dosage starting at 20 ppm at the suction of
the froth pump. The product water content decreased as the
demulsifier dosage increased. This trend occurs up to 50 ppm.
Similar to the tests in IPS units, enhanced mixing and increase
demulsifier dosage resulted in a lower diluted bitumen water
content.
[0062] ii) Centrifuge ON/OFF Test at the Demulsifier Dosage of 50
ppm
[0063] A test was conducted to assess demulsifier effectiveness at
the original location (prior art) and at the froth feed pump
suction. FIG. 11 shows the demulsifier performance results as a
function of injection location. The rectangular-shaped step-change
line labeled "demulsifier" indicates the demulsifier dosage and
location. The jagged line labeled "water" is the product water
content. The high setting represents the original location and the
low setting is for the froth pump suction. The dosage was constant
at 50 ppm. Before start-up, the demulsifier dosage was set at 50
ppm and production was relatively stable. When the test system was
started, there was an initial product water content increase. This
was due to the time delay between shut-down of the original system
and start-up of the test system resulting in no demulsifier. The
product water content thus increased until the demulsifier reached
the target dosage in the feed to the centrifuge, leading to a
decrease in water content. When the demulsifier injected from the
test system arrived at the centrifuges, the product water contents
dropped immediately to a level much lower than that through the
original system. When the test system was shut down and the
original system was back online, the water content returned to a
level higher than that through the test system. This on/off test
again supported the concept of enhanced mixing improved the
demulsifier effectiveness in diluted bitumen product water
reduction
[0064] From the foregoing description, one skilled in the art can
easily ascertain the essential characteristics of this invention.
However, the scope of the claims should not be limited by the
preferred embodiments set forth in the examples, but should be
given the broadest interpretation consistent with the description
as a whole.
* * * * *