Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02942998 2016-09-23
A METHOD FOR IMPROVING PARAFFINIC FROTH TREATMENT PROCESS IN OIL
SANDS EXTRACTION
FIELD
The present disclosure relates generally to the field of oil sands processing.
More
particularly, the present disclosure relates to paraffinic froth treatment.
BACKGROUND
This section is intended to introduce various aspects of the art, which may be
associated with the present disclosure. This discussion is believed to assist
in providing a
framework to facilitate a better understanding of particular aspects of the
present disclosure.
Accordingly, it should be understood that this section should be read in this
light, and not
necessarily as admissions of prior art.
Separation of bitumen from oil sands causes the formation of a bitumen-aqueous
slurry (i.e. bitumen froth) which contains a significant amount of
contaminants, namely water
(20-50%) and mineral solids (10-30%). The bitumen froth is subjected to a
paraffinic froth
treatment (PFT) process, in which the bitumen froth is diluted with a
hydrocarbon solvent to
reduce the viscosity and density of the oil phase, thereby accelerating the
settling of the solid
and water impurities. Furthermore, the addition of the paraffinic solvent
destabilizes
asphaltenes in the bitumen, causing them to precipitate out as solids. These
precipitated
asphaltene solids agglomerate with the mineral solids and water in the slurry
to form large
flocs, which settle rapidly in gravity settlers. One example high temperature
PFT process is
designed to reject approximately 40-50 wt% of the asphaltenes in the bitumen
to yield a
clean and dry bitumen product with significantly low solids content.
At a high level, PFT serves to separate water and solids from the bitumen in a
bitumen froth. Most of the water and solids, along with precipitated
asphaltenes, end up in
the tailings from the PFT. The degree of bitumen recovery is therefore an
important
parameter in PFT.
Figure us a simplified flow diagram of a conventional paraffinic froth
treatment (PFT)
process. Bitumen froth (2) is pumped from a froth storage tank (FST) (30) by a
froth feed
pump (FFP) (40) .to a 1st stage froth settling unit (FSU1) (100) to produce a
1st stage
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hydrocarbon-rich overflow (240) and a 1st stage solids-rich underflow (110).
Solvent (4) is
removed from the 1st stage hydrocarbon-rich overflow (240) in a solvent
recovery unit (SRU)
(9) to produce a bitumen product (6).
The 1st stage solids-rich underflow (110) is mixed with a solvent stream (4)
from the
solvent recovery unit (SRU) (9) and is fed to a 2nd stage froth settling unit
(FSU2) (160). The
2nd stage froth settling unit (FSU2) (160) produces a 2nd stage hydrocarbon-
rich overflow
(250) and a 2nd stage solids-rich underflow (170). The 2nd stage hydrocarbon-
rich overflow
(250) is added to the 1st stage froth settling unit (FSU1) (100) as a solvent
source and may
be combined with the bitumen froth (2) and mixed via a 1st stage mixer (70) to
form an FSU
feedstream before its addition to the 1st stage froth settling unit (FSU1)
(100) via feed line
(80), as illustrated. The 2nd stage solids-rich underflow (170) is passed to a
tailings solvent
recovery unit (TSRU) (8). The TSRU (8) produces tailings (230) which are sent
to an external
tailings area (ETA) (246). Typically, there are only two froth settling unit
(FSU) stages as
illustrated with 1st stage froth settling unit (FSU1) (100) and 2nd stage
froth settling unit
(FSU2) (160), but optionally a 3rd stage froth settling unit (FSU3) may also
be utilized in
series and is also contemplated herein.
Upstream of the 1st stage froth settling unit (FSU1) (100), a debris filter
(60) is used to
restrict entry of large size debris (e.g., petrified wood, geotextile
materials, coal particles,
organic matter, etc.) coming into the PFT system with the bitumen froth (2)
from the mine
site. Due to the quantity of large debris in the bitumen froth (2), the debris
filter (60) tends to
fill up or become plugged frequently.
To clear the debris filter (60), the debris filter (60) is periodically shut-
in and
backwashed with a water stream (45) in a backwash cycle. The resulting
backwash stream
(245), containing the filtered debris, water, and residual bitumen froth and
solvent is mixed
with tailings (230) from the TSRU (8) and directed to the external tailings
area (ETA) (246).
As the debris filter (60) frequently fills up or becomes restricted/plugged, a
large
number of backwash cycles are required. The use of the conventional debris
filter (60), while
designed to protect plugging in the downstream equipment, results in
additional equipment
and maintenance as well as significant losses of valuable hydrocarbon rich
bitumen froth
from the system due to the bitumen froth entrained in the backwash cycles. An
additional
problem is that the backwash stream (245) created by this filtering process
contains these
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otherwise valuable hydrocarbons which now (as contaminants) need to be removed
from the
particulate matter in the backwash stream (245) to acceptable levels before
the solids in the
backwash stream (245) can be disposed of, preferably with the tailings (230)
from the PFT
process. Fig. 1 illustrates where the backwash stream (245) may be sent to a
flash drum
(290) or "pump box" wherein the light hydrocarbons in the backwash stream
(245) may be
disengaged and sent to a flare system (300). However, even after flashing off
these light
hydrocarbons, the bitumen and a fraction of the solvent in the backwash stream
(245) does
not vaporize and end up as undesired contaminants in the external tailings
area (ETA) (246).
In the simplified flow diagram of Fig. 1, only one stage of the TSRU (8) (a
1st stage
TSRU) is shown. Optionally, embodiments may include a 2nd stage TSRU between
the 1st
stage TSRU and the external tailings area (ETA) (246).
Therefore, there is a need in the industry for an alternative or improved
paraffinic froth
treatment (PFT) process to recover bitumen which eliminates the generation of
the backwash
stream (245) from the paraffinic treatment (PFT) process.
SUMMARY
It is an object of the present disclosure to provide a paraffinic froth
treatment (PFT)
process to recover bitumen with lower solvent losses and contaminated debris
handling.
Described is a filterless paraffinic froth treatment (PFT). Instead of
filtering the
bitumen froth, piping and vessel internals are enlarged to be tolerant of
large debris from the
inlet to the PFT to the TSRU tailings system. The inventors have found that
the SRU system
does not require any modifications, as any debris will leave the system via
the froth settling
unit (FSU) underflow due to the density of the overflow product in the froth
settling unit
(FSU).
The modifications may include replacing static mixers with dual plate open
style
mixing elements, removing and/or increasing flow passage sizes on FSU feed
inlet baffle
plates, increasing pump flow passage size, and revising control valve
internals to increase
the open flow passage size.
The debris typical of an oils sands mining operation reports to froth settling
unit
underflow due to density difference and gravity with the media and also
asphaltene
precipitation.
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In a first aspect, the present disclosure provides a method for improving a
paraffinic
froth treatment (PFT) of bitumen froth including identifying a flow path, from
a bitumen froth
storage tank (FST) outlet through a froth feed pump (FFP) flow passage, a
debris filter flow
passage, a mixer flow passage, and a froth settling unit (FSU) flow passage,
to a tailings
solvent recovery unit (TSRU) inlet passage, identifying a minimum flow passage
size in the
flow path, excluding the debris filter flow passage, enlarging the flow path
to at least the
minimum flow passage size, and removing the debris filter from the flow path,
wherein a
filterless PFT process is provided.
In an embodiment disclosed, the flow path further includes a TSRU column
chimney
opening and a TSRU underflow pump.
In an embodiment disclosed, enlarging the flow path includes enlarging the FSU
flow
passage and the TSRU inlet passage.
In an embodiment disclosed, the flow path includes associated pipes and
valves, and
the enlarging includes enlarging the associated pipes and valves to at least
the minimum
flow passage size.
[0001] In
an embodiment disclosed, the flow path includes associated control valves,
and the enlarging includes enlarging the associated control valves to at least
the minimum
flow passage size.
In an embodiment disclosed, the minimum flow passage size is the FFP flow
passage
size.
In an embodiment disclosed, enlarging the FSU flow passage includes removing a
baffle plate from a FSU feed barrel.
In an embodiment disclosed, enlarging the TSRU inlet passage includes
enlarging
TSRU inlet valve seat plate openings.
In an embodiment disclosed, enlarging the mixer flow passage includes
replacing
mixers with dual plate open geometry mixing elements.
In an embodiment disclosed, the dual plate open geometry mixing elements
comprise
SulzerTM (KVM Type) or KomaxTM mixers.
In an embodiment disclosed, the minimum flow passage size is between about
1.75
and about 3.75 inches.
In an embodiment disclosed, the minimum flow passage size is about 2.5 inch.
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In an embodiment disclosed, an accumulator is provided between the FSU and a
solvent recovery unit (SRU) and floating debris is skimmed from the
accumulator to remove
debris that did not report to a solids-rich underflow of the FSU.
In a further aspect, the present disclosure provides a paraffinic froth
treatment (PFT)
process for bitumen froth including conveying unfiltered bitumen froth from a
bitumen froth
storage tank (FST) to a froth settling unit (FSU), the unfiltered bitumen
froth containing large
debris, providing solvent to the FSU, separating by density in the FSU,
substantially all of the
large debris to a FSU underflow, and conveying the FSU underflow to a tailings
solvent
recovery unit (TSRU).
In an embodiment disclosed, the large debris includes petrified wood,
geotextile
material, coal particles, organic particulate matter, or a combination
thereof.
In an embodiment disclosed, at least 50% by volume of the large debris is less
than
about 2.5 inches in diameter.
In an embodiment disclosed, at least a portion of the large debris is greater
than
about 1/4 inches in diameter.
In an embodiment disclosed, the process includes separating, by precipitation
in the
FSU, asphaltenes to the FSU underflow.
In an embodiment disclosed, the process includes slipstream filtering overflow
from
the FSU, to remove floating debris from the FSU.
In an embodiment disclosed, the floating debris is removed by skimming.
In a further aspect, the present disclosure provides an unfiltered paraffinic
froth
treatment (PFT) system including a froth feed pump (FFP) having a FFP flow
passage, a
mixer having a mixer flow passage, a froth settling unit (FSU) having a FSU
flow passage, a
solvent recovery unit (SRU) having a SRU flow passage, and a tailings solvent
recovery unit
(TSRU) having a TSRU inlet passage, wherein the FFP flow passage, the mixer
flow
passage, the FSU flow passage, and the TSRU inlet passage are adapted to allow
the free
passage of debris.
In an embodiment disclosed, the debris includes petrified wood or geotextile
material,
coal particles, organic particulate matter, or a combination thereof.
In an embodiment disclosed, the debris is large debris, able to pass through a
2.5
inch mesh sieve.
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In an embodiment disclosed, the mixer includes dual plate open geometry mixing
elements.
In an embodiment disclosed, the mixer is a SulzerTM (KVM Type) or KomaxTM
mixer.
In an embodiment disclosed, each of the FFP flow passage, the mixer flow
passage,
the FSU flow passage, and the TSRU inlet passage is at least 2.5 inches.
In an embodiment disclosed, the FSU further includes a slipstream filter
downstream
of an overflow from the FSU, adapted to skim floating debris from the FSU.
Other aspects and features of the present disclosure will become apparent to
those
ordinarily skilled in the art upon review of the following description of
specific embodiments in
conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present disclosure will now be described, by way of example
only, with reference to the attached Figures.
Fig. 1 is a simplified flow diagram of a conventional paraffinic froth
treatment (PFT)
process.
Fig. 2 is a simplified flow diagram of a FSU, TSRU, and SRU of a PFT process.
Fig. 3 is a feed barrel of the present disclosure.
Fig. 4 is a detail of the feed barrel of Fig. 3 along the section 4-4 showing
details of
the feed barrel baffle plate.
Fig. 5 is an exemplary graph of pressure drop and bitumen production rate in
relation
to a SRU feed heat exchanger of the SRU of Fig. 2.
Fig. 6 is an exemplary illustration of debris observed during testing.
Fig. 7 is an exemplary graph of pressure drop between FSU1 and FSU2.
Fig. 8 is an exemplary visualization of a computer flow simulation of a feed
barrel with
baffle plate.
Fig. 9 is an exemplary visualization of a computer flow simulation of the feed
barrel of
Fig. 8, with the baffle plate removed.
Fig. 10 is an exemplary illustration of a control valve internal components.
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Fig. 11 is an exemplary illustration of the control valve internal components
of Fig. 10,
having a reduced number of enlarged orifices.
Fig. 12 is a simplified flow diagram of a FSU and TSRU of a filterless PFT
process of
the present disclosure.
DETAILED DESCRIPTION
For the purpose of promoting an understanding of the principles of the
disclosure,
reference will now be made to the features illustrated in the drawings and
specific language
will be used to describe the same. It will nevertheless be understood that no
limitation of the
scope of the disclosure is thereby intended. Any alterations and further
modifications, and
any further applications of the principles of the disclosure as described
herein are
contemplated as would normally occur to one skilled in the art to which the
disclosure
relates. It will be apparent to those skilled in the relevant art that some
features that are not
relevant to the present disclosure may not be shown in the drawings for the
sake of clarity.
The PFT process may comprise at least three units: Froth Separation Unit
(FSU),
Solvent Recovery Unit (SRU) and Tailings Solvent Recovery Unit (TSRU). Mixing
of the
solvent with the feed bitumen froth may be carried out counter-currently in
two stages in
separate froth separation units. The bitumen froth comprises bitumen, water,
and solids. A
typical composition of bitumen froth is about 60 wt.% bitumen, 30 wt.% water,
and 10 wt.%
solids. The paraffinic solvent is used to dilute the froth before separating
the product bitumen
by gravity. The foregoing is only an example of a PFT process and the values
are provided
by way of example only. An example of a PFT process is described in Canadian
Patent No.
2,587,166 to Sury.
At the outset, for ease of reference, certain terms used in this application
and their
meaning as used in this context are set forth below. To the extent a term used
herein is not
defined below, it should be given the broadest definition persons in the
pertinent art have
given that term as reflected in at least one printed publication or issued
patent. Further, the
present processes are not limited by the usage of the terms shown below, as
all equivalents,
synonyms, new developments and terms or processes that serve the same or a
similar
purpose are considered to be within the scope of the present disclosure.
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Throughout this disclosure, where a range is used, any number between or
inclusive
of the range is implied.
A "hydrocarbon" is an organic compound that primarily includes the elements of
hydrogen and carbon, although nitrogen, sulfur, oxygen, metals, or any number
of other
elements may be present in small amounts. Hydrocarbons generally refer to
components
found in heavy oil or in oil sand. However, the techniques described are not
limited to heavy
oils but may also be used with any number of other reservoirs to improve
gravity drainage of
liquids. Hydrocarbon compounds may be aliphatic or aromatic, and may be
straight chained,
branched, or partially or fully cyclic.
"Bitumen" is a naturally occurring heavy oil material. Generally, it is the
hydrocarbon
component found in oil sand. Bitumen can vary in composition depending upon
the degree of
loss of more volatile components. It can vary from a very viscous, tar-like,
semi solid material
to solid forms. The hydrocarbon types found in bitumen can include aliphatics,
aromatics,
resins, and asphaltenes. A typical bitumen might be composed of:
19 weight (wt.) % aliphatics (which can range from 5 wt. % - 30 wt. %, or
higher);
19 wt. % asphaltenes (which can range from 5 wt. % - 30 wt. %, or higher);
30 wt. % aromatics (which can range from 15 wt. % - 50 wt. %, or higher);
32 wt. % resins (which can range from 15 wt. % - 50 wt. %, or higher); and
some amount of sulfur (which can range in excess of 7 wt. %), the weight %
based
upon total weight of the bitumen.
In addition, bitumen can contain some water and nitrogen compounds ranging
from
less than 0.4 wt. % to in excess of 0.7 wt. %. The percentage of the
hydrocarbon found in
bitumen can vary. The term "heavy oil" includes bitumen as well as lighter
materials that may
be found in a sand or carbonate reservoir.
The term "solvent" as used in the present disclosure should be understood to
mean
either a single solvent, or a combination of solvents.
The term "paraffinic solvent" (also known as aliphatic) as used herein means
solvents
comprising normal paraffins, isoparaffins or blends thereof in amounts greater
than 50 wt. c/o.
Presence of other components such as olefins, aromatics or naphthenes may
counteract the
function of the paraffinic solvent and hence may be present in an amount of
only 1 to 20 wt.
% combined, for instance no more than 3 wt. %. The paraffinic solvent may be a
C4 to 020
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or C4 to 06 paraffinic hydrocarbon solvent or a combination of iso and normal
components
thereof. The paraffinic solvent may comprise pentane, iso-pentane, or a
combination thereof.
The paraffinic solvent may comprise about 60 wt. % pentane and about 40 wt. %
iso-
pentane, with none or less than 20 wt. % of the counteracting components
referred above.
The terms "approximately," "about," "substantially," and similar terms are
intended to
have a broad meaning in harmony with the common and accepted usage by those of
ordinary skill in the art to which the subject matter of this disclosure
pertains. It should be
understood by those of skill in the art who review this disclosure that these
terms are
intended to allow a description of certain features described and claimed
without restricting
the scope of these features to the precise numeral ranges provided.
Accordingly, these terms
should be interpreted as indicating that insubstantial or inconsequential
modifications or
alterations of the subject matter described and are considered to be within
the scope of the
disclosure.
The articles "the", "a" and "an" are not necessarily limited to mean only one,
but rather
are inclusive and open ended so as to include, optionally, multiple such
elements.
Figure 2 illustrates a simplified exemplary PFT process. One may identify a
flow path,
starting with a bitumen froth (2) from a bitumen froth storage tank, (FST)
(30), through a froth
feed pump, (FFP) (40), through a debris filter (60), through a 1st stage mixer
(70) and to a 1st
stage froth settling unit (FSU1) (100) via feed line (80). A 1st stage feed
barrel (90) (see Fig.
3) having a baffle plate (95) (see Fig. 4) is provided at the inlet of the
feed line (80) to the 1st
stage froth settling unit (FSU1) (100).
The flow path continues, in the 1st stage solids-rich underflow (110) from the
1st stage
froth settling unit (FSU1) (100) through the 1st stage underflow pump (120),
through a 2'd
stage mixer (130), to a 2nd stage froth settling unit (FSU2) (160) via feed
line (140). A 2nd
stage feed barrel (150) (see Fig. 3) having a baffle plate (155) (see Fig. 4)
is provided at the
inlet of the feed line (140) to the 2nd stage froth settling unit (FSU2)
(160).
The flow path continues, in the 2' stage solids-rich underflow (170) from the
2nd
stage froth settling unit (FSU2) (160), through a 1st stage tailings solvent
recovery unit
(TSRU) inlet valve (190) to a 1st stage tailings solvent recovery unit (TSRU)
column (195).
The flow path continues, through the 1st stage TSRU column chimney opening
(196)
and on to the 1st stage TSRU underflow (197) from the 1st stage TSRU column
(195) through
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a 1st stage TSRU underflow pump (200), through a 2nd stage TSRU inlet valve
(210) to a 2nd
stage TSRU column (215).
The flow path continues, through the 2nd stage TSRU column chimney opening
(216)
and on to the 2nd stage TSRU underflow (217) from the 2nd stage TSRU column
(215)
through a 2nd stage TSRU underflow pump (220), tailings (230) are conveyed to
an external
tailings area (246). It should be noted that while Figure 2 is illustrated for
purposes of
discussion with a TSRU comprising two stages, TSRU systems with only one stage
are also
contemplated in embodiments herein.
Returning to the 2nd stage froth settling unit (FSU2) (160), the 2nd stage
hydrocarbon-
rich overflow (250) flows through a 2nd stage accumulator (270), 2nd stage
accumulator
bottoms pump (275), and is added to the 1st stage froth settling unit (FSU1)
(100) as a
solvent source and may be combined with the bitumen froth (2) before its
addition to the 1st
stage froth settling unit (FSU) (100), as illustrated.
The 1st stage hydrocarbon-rich overflow (240) flows to solvent recovery unit
(SRU) (9)
through a 1st stage accumulator (260) via a 1st stage accumulator bottoms pump
(265).
The solvent recovery unit (SRU) (9) includes equipment known in the art to
recover
solvent from the 1st stage hydrocarbon-rich overflow (240) to provide bitumen
product (6),
which includes but is not limited to heaters, columns, condensers, etc. (not
shown). A major
concern for plugging is that in the first part of the flow system (not shown)
of the solvent
recovery unit (SRU) (9), the 1st stage hydrocarbon-rich overflow (240) passes
through one or
more SRU feed heat exchangers to heat the 1st stage hydrocarbon-rich overflow
(240) to aid
in the solvent recovery process. The SRU feed heat exchangers tend to have
tube side or
shell side minimum flow paths that are as small as 1/4 inch (particularly on
the shell side
passes).
In table form, the illustrated major components include:
Froth Feed Pump (FFP) (40)
1st Stage Mixer (70)
1st Stage Froth Settling Unit (FSU1) (100)
1st Stage Feed Barrel (90)! Baffle Plate (95)
1st Stage Underflow Pump (120)
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2nd Stage Mixer (130)
2nd Stage Froth Settling Unit (FSU2) (160)
2nd Stage Feed Barrel (150)! Baffle Plate (155)
2nd Stage Underflow Valve (180)
1st Stage TSRU Inlet Valve (190)
1st Stage TSRU Column (195)
Chimney Opening (196)
1st Stage TSRU Underflow Pump (200)
2nd Stage TSRU Inlet Valve (210)
2nd Stage TSRU Column (215)
Chimney Opening (216)
2nd Stage TSRU Underflow Pump (220)
1st Stage Accumulator (260)
1st Stage Accumulator Bottoms Pump (265)
2nd Stage Accumulator (270)
2nd Stage Accumulator Bottoms Pump (275)
SRU Feed Heat Exchangers (not shown in Figures)
To protect the PFT process equipment downstream from the froth feed pump (FFP)
(40) from debris, a debris filter (60) having an opening size is traditionally
provided. The SRU
(9) is particularly susceptible to debris, as the minimum flow passage of the
SRU feed heat
exchangers may be in the order of 1/4 inches. As the SRU (9) cannot tolerate
large debris, a
conventional PFT process may use the debris filter (60) having an opening size
no larger
than about 1/4 to about 1/ inches.
Due to the problems associated with the debris filter (60) operation as
described
above, the inventors enlarged the opening size of the debris filter (60) to 1
inch and
monitored the pressure drop across a number of components in the PFT process
and
conducted surveillance at a number of points in the PFT process.
Referring to Fig. 5, in the SRU (9), the pressure drop (400) across the SRU
feed heat
exchanger was monitored and found to be insignificant. As illustrated, the
maximum pressure
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drop (400) encountered was about 20 kPa. The pressure drop (400) trends with
the bitumen
production rate (410), and surveillance showed no indication of plugging.
The 1st stage froth settling unit (FSU1) (100) (see Fig. 2) was drained to
conduct
surveillance. Minimal debris was found. Referring to Fig. 6, an exemplary
sample of debris
(420) is illustrated, ranging in size from about 1/4 inch x 1/4 inch to 1 inch
by about 2.5 inch.
The debris (420) was observed to be generally pliable, fibrous, with orange-
colored fibers
visible.
Significantly, it was discovered that the debris in the system that made its
way to the
1st stage froth settling unit (FSU1) (100) was only observed in the underflow
of the vessels,
i.e. the 1st stage solids-rich underflow (110), and not observed in the
overflow of the vessel,
i.e. 1st stage hydrocarbon-rich overflow (240). Thus, it was discovered that
debris was
ending up in the FSU underflows destined for the TSRU (8), and not flowing to
the SRU (9).
Therefore, using a small opening size for the debris filter (60) to protect
the SRU (9) was
unnecessary. The inventors thus investigated the flow path between the froth
feed pump
(FFP) (40) and the ETA (246).
Referring to Fig. 7, in the FSU, the pressure drop (430) between the 1st stage
froth
settling unit (FSU1) (100) and the 2nd stage froth settling unit (FSU2) (160)
was monitored.
As illustrated, the pressure drop (430) reached a maximum of about 150 kPa.
Less than
about 5 kPa of frictional pressure drop (430) was expected based on hydraulic
calculations
and was observed when the equipment was in a new and clean condition,
indicating that the
2nd stage feed barrel (150) was plugging. Inspection of the 2nd stage feed
barrel (150)
confirmed that plugging was occurring primarily at the baffle plate (155).
Within the debris flow path of an exemplary PFT process, each component has an
open flow passage, for example:
Component Flow Passage
(Example)
Froth Feed Pump (FFP) (40) 2 inch
1st Stage Mixer (70) 1.5 inch
1st Stage Froth Settling Unit 1.5 inch
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(FSU1) (100)
1st Stage Feed Barrel (90)!
Baffle Plate (95)
1st Stage Underflow Pump 2 inch
(120)
2nd Stage Mixer (130) 1.5 inch
2nd Stage Froth Settling Unit 1.5 inch
(FSU2) (160)
2nd Stage Feed Barrel (150)!
(Baffle Plate (155)
1st Stage TSRU Inlet Valve 1.5 inch
(190)
1st Stage TSRU Column (195) 6 inch
Chimney Opening (196)
1st Stage TSRU Underflow 2 inch
Pump (200)
2nd Stage TSRU Inlet Valve 1.5 inch
(210)
2nd Stage TSRU Column (215) 6 inch
Chimney Opening (216)
2nd Stage TSRU Underflow 2 inch
Pump (220)
Referring to the above, during the testing with the debris filter (60) having
a 1 inch
opening, it was discovered that debris of less an about 1 inch should readily
move through
the flow path, as the smallest flow passage is 1.5 inch. However, within the
flow path, one
can establish a selected minimum flow passage. That is, each component in the
flow path
shall have or be modified to have a flow passage equal to or larger than the
selected
minimum flow passage. For example, if the selected minimum flow passage was
set at 2
inches, the flow passage for each of the 1st stage mixer (70), the 1st stage
feed barrel (90) /
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baffle plate (95), the 2nd stage mixer (130), the 2nd stage feed barrel (150)!
baffle plate (155),
the 1st stage TSRU inlet valve (190), and the second stage TSRU inlet valve
(210), would be
enlarged to at least 2 inches. In another example, if the selected minimum
flow passage was
set at 2.5 inches, the flow passage for each of the froth feed pump (40), 1st
stage mixer (70),
the 1st stage feed barrel (90) / baffle plate (95), the 1st stage underflow
pump (120), the 2nd
stage mixer (130), the 2nd stage feed barrel (150) / baffle plate (155), the
1st stage TSRU inlet
valve (190), the 1st stage TSRU underflow pump (200), the second stage TSRU
inlet valve
(210), and the 2nd stage TSRU underflow pump (220) would be enlarged to at
least 2.5
inches.
In an embodiment disclosed, the selected minimum flow passage size may be
selected based on one of the components in the flow path. As an example, the
selected
minimum flow passage above is 2 inch, based on the froth feed pump (FFP) (40)
having a
flow passage of 2 inch. Each flow passage of the other components in the flow
path is thus
enlarged (as necessary) to at least the minimum flow passage size and the
debris filter (60)
removed from the flow path.
Depending on the nature of the equipment and its flow passage, some flow
passages
may be enlarged by modification or replacement with larger components, some
flow
passages may be enlarged by removal of restrictive components, some flow
passages may
be enlarged by replacing the equipment with a different type or style, or some
flow passages
may be enlarged by one or more of the above or combinations thereof.
In relation to the 1st stage froth settling unit (FSU1) (100) and the 2nd
stage froth
settling unit (FSU2) (160), openings in the baffle plate (95) and baffle plate
(155) may be
enlarged or the flow passage may be enlarged through the removal of the baffle
plate (95)
and baffle plate (155). A computer simulation of the operation of the 1st
stage feed barrel (90)
and 2nd stage feed barrel (150) (see also Figs. 3 and 4) was performed. In
particular,
referring to Figs. 8 and 9, the computer simulation indicated that removal of
the baffle plates
(95) and (155) from the respective 1st stage feed barrel (90) and the 2nd
stage feed barrel
(150) would have little impact on the flow distribution. In the present
example, the baffle plate
(95) and the baffle plate (155) are removed.
In relation to static mixers, the 1st stage mixer (70), 2nd stage mixer (130),
or other
mixers may include plates that form open, intersecting channels in which the
flow is divided
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into many channels, for example a SulzerTM SMV type mixer. The flow passage
may be
enlarged by enlarging the channels, but one may elect to replace the 2nd stage
mixer (130)
with an alternate type of mixer to enlarge the flow passage. One suitable
alternate type of
mixer includes a vortex mixer or a dual plate mixer, typically having mixing
elements with an
opening between them (open geometry), for example a SulzerTM KVM or a KomaxTM
type
mixer. In an embodiment disclosed, the 1st stage mixer (70) is similarly
replaced.
In relation to control valves, the 1st stage TSRU inlet valve (190), 2nd stage
TSRU inlet
valve (210), or other control valves may include a valve seat plate (320)
typically having
several orifices (330) of a relatively small diameter (see Fig. 10). To
enlarge the flow
passage, one may replace or modify the control valve or at least the valve
seat plate (320) to
provide at least one larger orifice (340). To maintain the open area, fewer
orifices (340) may
be required than orifices (330). Referring to Figs. 10 and 11 as an example, a
valve seat
plate (320) having ten orifices (330) of about 1.5 inch diameter (17.67 square
inches open
area) could be replaced or modified to provide a valve seat plate (320) having
four orifices
(340) of about 2.5 inch diameter (19.64 square inches open area). Alternately,
one may elect
to replace the control valve with a different type of valve having a larger
flow passage.
Referring to Fig. 12, after enlargement, the flow path includes, for example:
Component Flow Passage
Froth Feed Pump (FFP) (40) 2.5 inch
Debris Filter (60) removed
1st Stage Mixer (70) 2.5 inch minimum
1st Stage Froth Settling Unit 2.5 inch minimum (Baffle Plate
(FSU1) (100) (95) removed)
1st Stage Feed Barrel (90)
1st Stage Froth Settling Unit 2.75 inch
Underflow Pump (120)
2nd Stage Mixer (130) 2.5 inch minimum
2nd Stage Froth Settling Unit 2.5 inch minimum (Baffle Plate
(FSU2) (160) (155) Removed)
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2nd Stage Feed Barrel (150)
1st Stage TSRU Inlet Valve 2.5 inch minimum
(190)
1st Stage TSRU Column (195) > 6 inch
Chimney Opening (196)
1st Stage TSRU Underflow 3.7 inch
Pump (200)
2nd Stage TSRU Inlet Valve 2.5 inch minimum
(210)
2nd Stage TSRU Column (215) > 6 inch
Chimney Opening (216)
2nd Stage TSRU Underflow 3.7 inch
Pump (220)
Within the flow path, the above equipment is connected by associated piping
and
valves, and while the major associated piping (e.g. feed line (80), feed line
(140)) and major
associated valves (e.g. 1st stage TSRU inlet valve (190), and 2nd stage TSRU
inlet valve
(210)) are shown, additional associated piping and valves are not shown, but
which are
similarly enlarged as necessary to at least the selected minimum flow passage
size (in the
above example, 2.5 inch).
As described above, the flow path is enlarged in a retrofit example, but
similar flow
path and flow passage analysis and selection may be done during initial design
or
construction of the PFT (10) from the outset.
In operation, the bitumen froth (2) may include large debris. In an embodiment
disclosed, the large debris may be, for example, about 1 inch to 2.5 inch
debris. The debris
may include petrified wood, geotextile material, coal particles, organic
particulate matter, or a
combination thereof. In an embodiment disclosed, at least 50% by volume of the
large debris
is less than about 2.5 inches in diameter. In an embodiment disclosed, at
least a portion of
the large debris is greater than about 1/4 inches in diameter.
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If the bitumen froth (2) contains large debris, e.g. in froth storage tank
(FST) (30), the
debris may pass unfiltered through the PFT (10) from the froth feed pump (FFP)
(40) through
the 1st stage mixer (70) to the 1st stage froth settling unit (FSU1) (100)
through the 1st stage
feed barrel (90).
The debris, separated by density or gravity or both in the 1st stage froth
settling unit
(FSU1) (100) will be conveyed substantially into the 1st stage solids-rich
underflow (110). The
debris in the 1st stage solids-rich underflow (110) may pass unfiltered to the
2nd stage froth
settling unit (FSU2) (160) through the 2nd stage mixer (130) and the 2nd stage
feed barrel
(150).
Again, the debris, separated by gravity or density or both in the 2nd stage
froth settling
unit (FSU2) (160) will be conveyed into the 2nd stage solids-rich underflow
(170), and on
through the 1st stage TSRU inlet valve (190), through the chimney opening
(196) of the 1st
stage TSRU column (195), through the 1st stage TSRU underflow pump (200),
through the
2nd stage TSRU inlet valve (210), through the chimney opening (216) of the 2nd
stage TSRU
column (215), through the 2nd stage TSRU underflow pump (220), and end up with
the
tailings (230) directed to the external tailing area (ETA) (246).
In the event that debris ends up in the 1st stage hydrocarbon-rich overflow
(240) from
the 1st stage froth settling unit (FSU1) (100), the present disclosure
provides for this
contingency by including the option to use a slip-stream filter downstream of
the 1st stage
hydrocarbon-rich overflow (240) from the 1st stage froth settling unit (FSU1)
(100). Floating
debris may be skimmed from the 1st stage accumulator (260) to remove debris
that did not
report to the 1st stage solids-rich underflow (110) of the 1st stage froth
settling unit (FSU1)
(100).
Similarly, an option to use a slip-stream filter downstream of the 2nd stage
hydrocarbon-rich overflow (250) from the 2nd stage froth settling unit (FSU2)
(160) is
contemplated. Floating debris may be skimmed from the 2nd stage accumulator
(270) to
remove debris that did not report to the 2nd stage solids-rich underflow (170)
of the 2nd stage
froth settling unit (FSU2) (160).
It should be understood that numerous changes, modifications, and alternatives
to
the preceding disclosure can be made without departing from the scope of the
disclosure.
The preceding description, therefore, is not meant to limit the scope of the
disclosure.
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Rather, the scope of the disclosure is to be determined only by the appended
claims and
their equivalents. It is also contemplated that structures and features in the
present examples
can be altered, rearranged, substituted, deleted, duplicated, combined, or
added to each
other.
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