Note: Descriptions are shown in the official language in which they were submitted.
CA 02864780 2014-09-23
NS-51 6
SYSTEM AND METHOD FOR IMAGE-BASED ANALYSIS OF
A SLURRY AND CONTROL OF A SLURRY PROCESS
FIELD OF THE INVENTION
The present invention relates to analysis of slurries in a slurry process,
and more particularly to a system and method suitable for image-based analysis
of various oil sands extraction slurries produced or treated during a process
for
extracting bitumen oil sands ore and the control of such bitumen extraction
processes.
BACKGROUND OF THE INVENTION
Extraction of bitumen from mined oil sands ore has been practiced in
Alberta, Canada, for many years. Bitumen extraction processes can be water-
based processes, solvent-based processes or a combination of water-based and
solvent-based processes. In water-based bitumen extraction processes,
generally, the mined oil sands ore is crushed and mixed with heated water,
steam, and caustic (NaOH) to produce an oil sands slurry that is hydro-
transported in a pipeline to a primary separation station. During hydro-
transport,
turbulent flow of the slurry in the pipeline causes bitumen films surrounding
the
sand particles to begin to separate, attach to entrained air bubbles, and form
bitumen droplets. The primary separation station may comprise a primary
separation vessel (PSV) wherein the oil sands slurry is introduced to float
the
bitumen to the top of the PSV as a bitumen-rich froth, which is generally
referred
to as "primary bitumen froth", while middlings remain suspended in the PSV,
and
an underflow settles to the bottom of the PSV. The middlings, underflow and
tailings from the PSV may then be subjected to secondary flotation treatment
to
recover residual bitumen contained therein (generally referred to as
"secondary
bitumen froth"). The primary bitumen froth, secondary bitumen froth or both is
further treated with a diluent, such as naphtha or paraffin, and subjected to
gravitational or centrifugal separation to separate diluted bitumen from
tailings.
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Oil sands that are processed by bitumen extraction processes are highly
variable in their physical properties. Variations in the physical properties
of the oil
sands feed stock and the various oil sands slurries derived therefrom will
affect
the mechanical and chemical separation phenomena in the bitumen extraction or
tailings reclamation processes. When designing and optimizing bitumen
extraction and/or tailings reclamation processes, it can therefore be
difficult to
ascertain whether a change in process performance is caused by a deliberate
change to the process or to chance variation in the slurry/tailings processed
by
the process. Accordingly, analyzing the slurries, including tailings, to
determine
their physical properties can yield information that is valuable to predicting
and
optimizing bitumen extraction and tailings treatment processes, and diagnosing
problems in such processes. However, the complicated and heterogeneous
nature of oil sands extraction slurries presents unique practical obstacles
for
conventional analysis equipment. For example, sand grains and solid fines
suspended in the oil sands extraction slurries will tend to erode sensing
elements
placed directly in a slurry flow path. Further still, bitumen in oil sands
extraction
slurries tend to coalesce and interfere with the proper operation of sensing
equipment. While these challenges can be addressed to an extent by using a
sampling device to remove discrete samples of oil sands extraction slurries
from
a slurry transport line, repeated operation of a sampling device may wear and
cause failure of seals associated with the sampling device.
Accordingly, there is a need in the art for systems and methods of
analyzing slurries such as oil sands extraction slurries. Preferably, such
systems
and methods address the unique challenges posed by slurries such as oil sands
extraction slurries, permit continuous sampling of slurries from a slurry
transport
line, rapidly analyze the slurries for real-time control and monitoring of
bitumen
extraction and tailings treatment processes, and provide a tool that can be
used
for optimization of slurry process performance.
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SUMMARY OF THE INVENTION
The present invention is directed to computer-implemented, image-based
analysis of a slurry and control of a slurry process. In particular, the
invention
may be suitable for characterizing oil sands extraction slurries produced or
treated by oil sands extraction slurry processes, including bitumen extraction
processes, bitumen froth treatment processes, and tailings treatment
processes.
In one aspect, the present invention provides a system for characterizing a
slurry, the system comprising:
(a) a flow tube comprising at least one transparent viewing portion, a
slurry inlet, and a slurry outlet;
(b) at least one camera positioned to image the slurry flowing through
the viewing portion of the flow tube; and
(c) a computer comprising a processor operatively connected to the
camera, and a memory storing a set of instructions, wherein the
processor is responsive to the set of instructions to execute a
method comprising the steps of:
imaging the slurry flowing through the at least one viewing
portion of the flow tube to produce at least one digital image
of the slurry; and
(ii) analyzing the at
least one digital image to determine at least
one slurry characteristic.
In another aspect, the present invention provides a method for
characterizing a slurry, the method comprising the steps of:
(a) flowing the slurry through a flow tube comprising at least
one
transparent viewing portion;
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(b) imaging the slurry with at least one camera as the slurry flows
through the at least one viewing portion to produce at least one
digital image of the slurry; and
(c) analyzing the at least one digital image with a computer to
determine at least one slurry characteristic.
In another aspect, the present invention provides a method for online
control of a slurry process for processing a slurry, the method comprising the
steps of:
(a) flowing the slurry through a flow tube comprising at least one
transparent viewing portion;
(b) imaging the slurry with at least one camera as the slurry flows
through the at least one viewing portion to produce at least one
digital image of the slurry;
(c) analyzing the at least one digital image with a computer to
determine at least one slurry characteristic;
(d) determining a performance metric for the slurry process based on a
predictive relationship with the determined at least one slurry
characteristic; and
(e) based on the determined at least one slurry characteristic and the
determined performance metric, adjusting an operating parameter
of the slurry process to adjust the performance metric towards a
target value or range.
Other features will become apparent from the following detailed
description. It should be understood, however, that the detailed description
and
the specific embodiments, while indicating preferred embodiments of the
invention, are given by way of illustration only, since various changes and
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modifications will become apparent to those skilled in the art from this
detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
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
following figures. It is understood that the drawings provided herein are for
illustration purposes only and are not necessarily drawn to scale.
Fig. 1 is a schematic depiction of one embodiment of the system of the
present invention for analyzing oil sands extraction slurries.
Fig. 2 is a functional block diagram of one embodiment of a computer of
the system of the present invention for analyzing oil sands extraction
slurries.
Fig. 3 is a flow chart of the steps of one embodiment of the method of the
present invention for analyzing oil sands extraction slurries.
Fig. 4a and Fig. 4b are representations of digital images of an oil sands
extraction slurry created by one embodiment of the system of the present
invention, imaged at a first time instance and a second time instance,
respectively. Fig. 4c is a superposition of the digital images of Fig. 4a and
Fig.
4b.
Fig. 5a is graphical representation of an exemplary distribution of bitumen
droplet rise velocity in an oil sands extraction slurry. Fig. 5b is a
graphical
representation of an exemplary predictive relationship between bitumen droplet
rise velocity and bitumen recovery in an oil sands extraction slurry for a
hot/warm
water bitumen extraction process.
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CA 02864780 2016-07-26
Fig. 6 is a representation of a digital image of an oil sands extraction
slurry created by one embodiment of the system of the present invention, with
the colors in negative.
DESCRIPTION OF THE PREFERRED EMBODIMENT
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.
The present invention relates generally to a system and method for image-
based analysis of a slurry and control of a slurry process. When describing
the
present invention, all terms not defined herein have their common art-
recognized
meanings. To the extent that the following description is of a specific
embodiment
or a particular use of the invention, it is intended to be illustrative only,
and not
limiting of the claimed invention.
As used herein, the term "slurry" refers a mixture of a liquid and particulate
objects, which may be an immiscible second liquid, gas or solid. As used
herein,
the term "oil sands extraction slurry" refers to a slurry produced during any
step
of a process for extracting bitumen from oil sands, with such steps including
water, solvent or solvent/ water extraction of bitumen, bitumen froth
treatment,
and tailings treatment. Without limitation, "oil sands extraction slurry"
includes
slurries of the following types: any slurry comprising mined oil sands and
water
(i.e., an "oil sands slurry") that is conventionally fed into a primary
separation
vessel (PSV) in hot/warm water bitumen extraction from oil sands ores; any
=
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slurry in bitumen froth, middlings, underflow and tailings streams produced
during
the hot/warm water bitumen extraction process; any slurry streams produced
during a bitumen froth treatment process, for example, froth treatment
tailings;
any slurry streams produced during oil sand tailings treatment; and, any
slurry
that is produced during solvent or solvent/water extraction of bitumen from
oil
sands. An oil sands extraction slurry may contain particulate objects such as
bitumen droplets, sand grains, entrained air bubbles, and other solid fine
particles.
As used herein "slurry process" means any process that either produces a
slurry or treats a slurry or both. Without limitation, a "slurry process"
includes a
"oil sands extraction slurry process", which may be any slurry process that
operates on an oil sands extraction slurry, such as a hot/warm water bitumen
extraction process, a solvent or solvent/water bitumen extraction process, a
bitumen froth treatment process, or a tailings treatment process.
Fig. 1 provides a schematic depiction of one embodiment of the system
10 of the present invention. In general, the system 10 includes a flow tube 20
with a transparent viewing portion 22, a camera 60, and a computer 70
operatively connected to the camera 60. In Fig. 1, the dashed lines represent
operative connections between two components, which connections may be
either wired or wireless connections, or a combination of wired and wireless
connections.
By way of illustration, the embodiment shown in Fig. 1 will be further
described with reference to oil sands extraction slurries, and more
particularly
with reference to an oil sands slurry that is fed from a slurry hydro
transport
pipeline 30 into a primary separation vessel (PSV) (not shown) in a hot/warm
water bitumen extraction process represented by reference numeral 31.
However, it will be understood that reference numeral 31 can generally be any
slurry process. Further, the slurry transport line 30 can be a line that feeds
a
different type of oil sands extraction slurry at a different step of an oil
sands
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CA 02864780 2014-09-23
extraction slurry process. Accordingly, the present invention is not limited
by the
immediate source of the slurry in the slurry transport line 30. In other
examples,
the slurry transport line 30 may be lines that transport middlings, underflow
or
tailings from various steps of the oil sands extraction slurry process 31,
which
may be a solvent or solvent/water based bitumen extraction process, a bitumen
froth treatment process, or a tailings treatment process.
The flow tube 20 provides a conduit for controlled flow of the slurry in the
viewing portion 22, between a slurry inlet 24 to a slurry outlet 26. As used
herein, the term "upstream" in describing the relative position of a first
element
associated with the flow tube 20 to a second element associated with the flow
tube 20 means that the first element is located, relative to the second
element, in
the flow direction from the slurry outlet 26 towards the slurry inlet 24.
Conversely,
the term "downstream" in describing the relative position of a first element
associated with the flow tube 20 to the second element associated with the
flow
tube 20 means that the first element is located, relative to the second
element, in
the flow direction from the slurry inlet 24 towards the slurry outlet 26.
In the embodiment shown in Fig. 1, the flow tube 20 comprises a
generally cylindrical tube, made of colourless, transparent glass. The tube is
oriented vertically lengthwise and measures about 1.8 meters in length, with a
circular cross section with a diameter of about 5 centimeters. In other
embodiments (not shown), the flow tube 20 may have a different cross sectional
shape, orientation, and size. Further, portions of the flow tube 20 other than
the
viewing portion 22 may be opaque.
The slurry inlet 24 allows for inflow of the slurry into the flow tube 20, so
that it can be imaged in the viewing portion 22. In the embodiment shown in
Fig.
1, the slurry inlet 24 is formed in the side wall of the tube, and is in fluid
communication, via slurry inlet line 28, with a slurry transport line 30. The
slurry
inlet line 28 includes a slurry inlet valve 32 to selectively open and close
the
slurry inlet 24 of the flow tube 20. The slurry inlet line 28 may have a
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CA 02864780 2014-09-23
considerable length so that the flow tube 20, camera 60 and computer 70 can be
located at any desired distance away from the slurry transport line 30. In
embodiments, for example, the slurry inlet line 28 may transport the slurry
over a
significant distance of more than 1 meter, 5 meters, 10 meters, or 20 meters
from
the slurry transport line to the slurry inlet 24 of the flow tube 20. This
facilitates
physically configuring the components of the system 10, as appropriate for a
particular environment, and allows flow tubes 20 of multiple systems 10 to be
located near a common shared computer 70.
The slurry outlet 26 allows for discharge of the slurry from the flow tube
20. In the embodiment shown in Fig. 1, the oil sands slurry flows primarily in
an
upwards direction from the slurry inlet 24 to the slurry outlet 26 formed at
the top
of the flow tube 20. The slurry outlet 26 is formed into an overflow weir that
discharges the slurry into an open reservoir 34, maintained at atmospheric
pressure. The overflow weir allows the slurry passing through slurry outlet 26
to
overflow smoothly into the open reservoir 34, so as to avoid jetting the
slurry out
of the flow tube 20 in a fountain-like manner, and recirculation of the slurry
back
into the flow tube 20. The discharged slurry in the reservoir 34 may be
collected
for chemical analysis if desired.
The transparent viewing portion 22 of the flow tube 20 exposes the oil
sands slurry within the flow tube 20 for imaging by the camera 60. In the
embodiment shown in Fig. 1, the viewing portion 22 of the flow tube 20 is
formed
by two opposed planar surfaces about 20 centimeters in length, and separated
by a narrow gap, so that the viewing portion 22 is laminar in form. The flow
tube
20 and its viewing portion 22 may be manufactured by glassblowing a single
tubular section of molten glass tubing and flattening the tubing to form the
viewing portion. Alternatively, the viewing portion 22 may be constructed from
two discrete pieces of glass plate that are placed opposite each other, and
connected by couplers in a fluid tight manner to the adjacent portions of the
flow
tube 20 immediately above and below the plates. The size of the gap, measured
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in the direction of the central viewing angle of the camera 60, is preferably
sufficiently small so that the particulate objects pass through the viewing
portion
in a single layer (i.e., without overlapping each other) so that their
boundaries
can be readily delineated. At the same time, the gap is preferably
sufficiently
large to avoid unduly impeding the flow of the slurry or a causing a build up
of
particulate objects in the slurry. In the embodiment shown in Fig. 1, the gap
between the inside surfaces of the plate-like surfaces is about 2 millimeters,
whereas the adjacent upstream and downstream portions of the flow tube 20
have a diameter of about 5 centimeters. It has been found that this thickness
of
gap allows upward passage of bitumen droplets in an oil sands slurry where the
bitumen droplets range in size from about 100 pm to about 600 pm while
avoiding agglomeration of the bitumen droplets. The person skilled in the art
will
be able to select different sizes of gaps to suit particular slurry
compositions and
flow rates through the viewing portion.
In other embodiments (not shown) the viewing portion 22 may have a
different configuration and size. The viewing portion 22 may be configured so
that the flow of the slurry through the viewing portion 22 is substantially
non-
turbulent for a given flow condition and slurry composition. Except for the
narrowing of the flow tube 20 to form the viewing portion 22, it is preferable
that
convergences and divergences in the cross-section of the flow tube 20 be
minimized or avoided, as they may trap bitumen droplets, or cause
recirculation
zones that interfere with the flow of the slurry through the flow tube 20.
Embodiments of the flow tube 20 may also include a carrier fluid inlet 36 to
allow inflow of a carrier fluid into the flow tube 20, upstream of the viewing
portion
22. The carrier fluid may assist the upward flow of the slurry through the
viewing
portion 22 of the flow tube 20, and prevent buildup of slower moving
particulate
objects upstream of the viewing portion 22. In addition, the carrier fluid,
being
relatively free of particulate objects, allows for more precise control over
the flow
rate of the slurry through the viewing portion 22 of the flow tube 20. In the
CA 02864780 2014-09-23
embodiment shown in Fig. 1, the carrier fluid inlet 36 is positioned
downstream of
the slurry inlet 24, but upstream of the viewing portion 22. A carrier fluid
line 38
provides fluid communication between a carrier fluid source, such as water
vessel 40, and the carrier fluid inlet 36. The carrier fluid line includes
carrier fluid
valve 42 to selectively open and close the carrier fluid inlet 36. Embodiments
of
the flow tube 20 may also include a bottom outlet 44 with a bottom valve 46,
which may be used in conjunction with the carrier fluid inlet 36 for flushing
the
flow tube 20 as will be described below.
Embodiments of the flow tube 20 may include a transparent second
viewing portion 23 to expose the slurry to imaging by a second camera 62. In
the
embodiment shown in Fig. 1, the second viewing portion 23 is formed in a
similar
manner as the viewing portion 22, by a narrowing of the side walls of the flow
tube 20, but is shorter in length than viewing portion 22 measuring about 10
centimeters in length. The flow tube 20 may comprise an upper part 25 that
includes viewing portion 22, and a separately formed lower part 27 that
includes
the second viewing portion 23. The lower end of the upper part 25 may be
coupled in a fluid tight manner to the upper end of the lower part 27 using
suitable fittings as are known in the art. The second viewing portion 23 may
be
positioned downstream of the slurry inlet 24 and the carrier inlet 36, at a
sufficient
distance away from the immediate zone of influence inflowing slurry and
carrier
fluid, near the bottom of the flow tube 20. This positioning of the second
viewing
portion 23 allows for imaging of the underflow in the flow tube 20 ¨ i.e.,
that
portion of the slurry that is not carried upwards through the viewing portion
22.
Embodiments of the system 10 may include a dilution means for diluting
the slurry prior to entering the flow tube 20. Dilution of the slurry may be
necessary to reduce the spatial density of particulate objects in the slurry
so that
they can be clearly delineated when imaged by the camera 60. In the
embodiment shown in Fig. 1, for example, the dilution means include a dilution
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CA 02864780 2014-09-23
fluid line 48 that provides fluid communication between the water vessel 40
and
the slurry inlet line 28, upstream of the slurry inlet 24.
Embodiments of the system 10 may also include a temperature control
means for controlling the temperature of the slurry flowed through the flow
tube
20. In the case of an oil sands extraction slurry, varying the temperature of
the
slurry may help prevent bitumen droplets from coalescing with each other, so
as
to improve the accuracy and reliability of the image-based analysis,
especially
where the slurry characteristic to be determined is bitumen droplet size. It
may
also be used to control the viscosity of the oil sands extraction slurry, and
allow
for controlled experimentation on the effect of temperature on slurry
properties. In
the embodiment shown in Fig. 1, for example, the temperature control means
includes a heat exchanger 50 associated with the fluid vessel to control the
temperature of the water that is discharged from the water vessel 40 into the
dilution fluid line 44 or the carrier fluid line 38. In one embodiment, the
temperature of the water is controlled at about 10 to 25 degrees Celsius. In
other
embodiments (not shown), the temperature control means may include other
suitable devices known in the art for heating or cooling one or more of the
slurry,
the dilution fluid, or the carrier fluid, and controlling their temperature.
The camera 60 images the slurry as it passes through the viewing portion
22 of the flow tube 20 to produce a digital image of the slurry. The camera 60
may comprise any device that digitally encodes a still image or a video image
of
the slurry. Digital camera 60 technology is known by persons skilled in the
art
and does not itself constitute part of the present invention. The digital
image may
comprise any numeric representation of an image of the slurry. As is known by
persons skilled in the art, digital images may assume one of several format
types. One known format type is a raster format in which the digital image is
represented by a notional array of pixels, with each pixel representing a
unique
spatial position within the image, and with each pixel having one or more
associated numerical values representing the brightness of one or more colors.
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In one embodiment, the camera 60 is configured to resolve a particular
object in the slurry having a size of about 600 pm or smaller, and more
particularly 100 pm or smaller. As is known by persons skilled in the art,
such
resolution may be achieved with a camera 60 equipped with a suitable
combination of optical lens, and digital image sensor. As used in this
context, the
term "resolve" means that the digital image produced by the camera 60 encodes
information that makes it possible to distinguish between two objects
separated
by the specified object size, at the angular distance formed by the camera 60
and
the viewing portion 22 of the flow tube 20. In one embodiment, the camera 60
is
a high speed video camera capable of capturing images at a frequency of about
500 frames per second. In one embodiment, the camera 60 may be configured
with optical or computerized equipment to selectively filter certain light
wavelengths corresponding to certain colors to enhance the contrast of certain
colors encoded by the digital images to facilitate their analysis.
Embodiments of the system 10 may include multiple cameras 60, 62
positioned to image the slurry as it flows the viewing portion 22 and second
viewing portion 23, respectively, of the flow tube 20. As will be appreciated,
when
a camera 60 is placed sufficiently close to viewing portion 22, its field of
view
may be too limited to simultaneously capture both viewing portions 22 and 23.
The use of multiple cameras 60, 62 allows for greater spatial coverage of the
flow
tube 20, while preserving a desired resolution. In the embodiment shown in
Fig.
1, for example, a first camera 60 is positioned to capture an image of the
slurry in
viewing portion 22 of the flow tube 20, while a second camera 62 is positioned
to
capture an image of the slurry in second viewing portion 23 of the flow tube
20. In
other embodiments (not shown) multiple cameras may be used to image different
parts within the same viewing portion 22, or second viewing portion 23.
The computer 70 analyzes the digital image to determine one or more
slurry characteristics. In embodiments, the computer 70 may also control the
actuation of the various components of the system 10 such as the valves, the
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temperature control means, and the camera 60. It will be appreciated that a
computer 70 is practically needed to analyze the digital images because of the
large amount of information encoded by digital images (e.g., a single, high
resolution, digital image in raster format may have millions of pixels, each
associated with multiple color values), and the volume of digital images that
could be generated by high frequency, intermittent or continuous analysis of a
slurry diverted from a slurry process over an extended operating time.
The computer 70 may comprise a general purpose computer, a special
purpose computer, a microcomputer, an integrated circuit, a programmable logic
device or any other type of computing technology known in the art that is
capable
of analyzing the information encoded by the digital images. It will further be
understood that the computer 70 may comprise computerized components of the
camera 60. In the embodiment shown in Fig. 1, the computer 70 includes a
general purpose computing device having a processor, a memory, buses
associated with the processor to operatively connect the processor to the
memory and the camera 60, and a display output. In embodiments, the
processor may also be operatively connected to other components of the system
10 or of the slurry process 31 to control their actuation. The memory stores a
set
of instructions which are executed by the processor to analyze the digital
image
and perform the control functions.
Fig. 2 shows a functional block diagram of an embodiment of a computer
70 used in the present invention for analyzing oil sands extraction slurries.
A
camera interface / image acquisition module 72 controls the acquisition of
digital
images from the camera 60, and may also control the camera 60 to determine
when the camera 60 captures images of the oil sands extraction slurries and
settings (e.g., shutter speed, focal length, magnification, color filtration,
etc.)
associated with the camera 60. The image analysis module or modules 74
control the analysis of the digital images to determine one or more slurry
characteristics. Without limitation, these type of slurry characteristics in
the case
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of an oil sands extraction slurry may include bitumen droplet size and shape,
bitumen droplet rise or settling velocity, bitumen droplet shape, slurry
color, slurry
turbidity, sand grain particle shape, slurry conditioning, slurry turbidity,
predicted
bitumen recovery rate, fines concentration, gelation, predicted froth quality,
aeration, agglomeration rate, and blending. The particular algorithm used to
analyze the digital image will depend on the slurry characteristic to be
determined. Further, it will be appreciated that image analysis modules 74 may
directly determine some of the slurry characteristics by processing of the
digital
images, while indirectly determining other slurry characteristics based on pre-
determined predictive relationships with directly determined slurry
properties. The
display output module 76 controls an output device (e.g., a display monitor,
an
audible signal, a printer) operatively connected to the computer 70 to
generate
an output of the determined slurry characteristics. The process control module
76
controls one or more components of the slurry process 31 to adjust the slurry
characteristics.
The use and operation of one embodiment of the system 10 is now
described in a non-limiting example, with reference to the steps of method 100
shown in the flow chart of Fig. 3, to analyze an oil sands extraction slurry
such as
an oil sands slurry from a bitumen extraction process.
The system 10 is set up as shown in Fig. 1 with the slurry input line 28
connected to the slurry transport line 30 which feeds an oil sands slurry to a
PSV
(step 110). It will be understood that the present invention is not limited by
the
immediate source of the slurry in the slurry transport line 30. In other
embodiments of the method, the slurry transport line 30 may be lines that
transport middlings, underflow or tailings from parts of the slurry process 31
involved in the hot/warm water bitumen extraction process, including bitumen
froth treatment and tailings treatment.
Where the flow tube 20 is made of glass, it has been found that wetting
the flow tube 20 with water before flowing an oil sands slurry through the
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CA 02864780 2014-09-23
tube 20 helps prevent a build up of bitumen droplets in the flow tube 20,
which
can foul the flow tube 20. This water wetting process may be achieved by
immersing the flow tube 20 in water for a few days prior to being installed
into the
system 10.
The dilution fluid line 48 feeds water from the water vessel 40 into the
slurry inlet line 28 (step 120), such that the diluted oil sands slurry flows
through
the slurry inlet into and into the flow tube 20 at a flow rate of about 5
liters per
second. At the same time, the carrier fluid valve is opened so that the
carrier
fluid line feeds water from the water vessel 40 through the carrier fluid line
38
and into the flow tube 20 at a flow rate of about 1 liter per second.
In the flow tube 20, the combination of the diluted oil sands slurry entering
through slurry inlet 24 and water entering through the carrier fluid inlet 36
flow
upwards within the flow tube 20 (step 130). The majority of the oil sands
slurry
flows upwards through the viewing portion 22 of the flow tube 20 for imaging
by
the camera 60, and ultimately through the slurry outlet 26 into reservoir 34.
However, some of the slower moving particulate solids in the oil sands slurry
may
settle downwards in the flow tube 20 through the second viewing portion 23.
In order to prevent the particulate objects from re-circulating or
agglomerating in the flow tube 20 and interfering with the imaging process,
the
computer 70 controls the valves to periodically flush the flow tube 20. This
may
be accomplished by temporarily closing slurry inlet line 28, while opening the
carrier fluid valve 42 and bottom valve 46. As the carrier fluid line 38
discharges
water into the flow tube 20, any particulate objects are flushed either
through the
bottom valve 46 or the slurry outlet 26 at the top of the flow tube 20.
The camera 60 images the oil sands slurry as it flows through viewing
portion 22 of the flow tube 20 (step 140). Meanwhile, camera 62 images a
portion
of the oil sands slurry as it settles downwards through the second viewing
portion
23 of the flow tube 20. As an example, the camera 62 and second viewing
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portion 23 may be used to diagnose problems such as poor aeration, liberation
or
solids attachment of bitumen droplets, which may be responsible for these
bitumen droplets settling in the PSV and being recovered as underflow rather
than floating to the top of the PSV and being recovered as primary bitumen
froth.
In one non-limiting example, the computer 70 actuates the camera 60 to
produce a first digital image of the oil sands slurry at a first time
instance, t1, as
shown in Fig. 4a, and a second digital image of the oil sans slurry at a later
second time instance, t2, as shown in Fig. 4b. The time elapsed from the first
time instance to the second time instance is sufficiently small so that at
least
some of the same particulate objects are visible in both of the images. As an
alternative, a first camera 60 and a second camera may be used to capture the
same particulate objects in two disjoint parts of the viewing portion 22. The
person skilled in the art will be able to select an appropriate time interval
between
the successive digital images, based on the flow rate of the oil sands slurry
through the viewing portion 22 of the flow tube 20, and the field of view of
the
camera 60. In yet another alternative, the computer 70 actuates the camera 60
so that the exposure time of the camera 60 is sufficiently long to produce a
streaked image of the particulate object as the particulate object moves
through
the field of view of the camera 60. The person skilled in the art will be able
to
select an appropriate exposure time based on the flow rate of the oil sands
slurry
through the viewing portion 22 of the flow tube 20 to produce a streak having
a
length within a desired range. Also, it will be understood that the computer
70
may actuate the camera 60 to continuously take images at certain time
intervals,
or that the camera 60 may take a video image of the oil sands slurry.
The computer 70 acquires the digital images produced by the camera 60
and analyzes them to determine one or more slurry characteristics (step 150).
Although the analysis of the digital images are described in the following
examples in notional terms, the person skilled in the art will appreciate that
the
analysis is actually implemented through algorithms that operate
mathematically
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on the values that numerically define the digital image to extract meaningful
information about the slurry characteristics.
In one analysis example, the computer 70 predicts bitumen recovery rate
for the oil sands slurry in a PSV by determining the rise velocity of bitumen
droplets through the viewing portion 22 of the flow tube 20. The rise velocity
of
bitumen droplets can be determined in accordance with a variety of methods. In
one method, the computer 70 compares a first digital image as shown in Fig. 4a
with a second digital image as shown in Fig. 4b. As shown in Fig. 4c, the
first
and second images are super-imposed, and the contrast is adjusted to filter
out
lighter colour particulate objects representing sands grains, and better
discern
the darker colour bitumen droplets. The computer 70 analyzes the super-
imposed image to determine the geometry (size and shape) of bitumen droplets
and identify pairs of particulate objects having sufficiently similar geometry
that
can be assumed to represent the same object at the first instance, t1, and at
the
second time instance, t2. As an example, this comparison may be performed by
identifying clusters of pixels having similar color values and adjacency to
other
pixels. In Fig. 4c, for example, the computer 70 may identify bitumen droplets
80
and 80', as being the same bitumen droplet moving from a first position at
time
instance t1 to a second position at time instance t2. The computer 70 may
calculate the displacement of the bitumen droplet 80, 80' over the time
interval
between time instance t1 and t2 to determine the rise (or settling) velocity
of the
bitumen droplet.
In another method, the computer 70 identifies a dark colour streak in a
single digital image representing the path of the bitumen droplet as it rises
through the field of view of the camera 60. As an example, the streak may be
identified by pixels within a certain colour range that are adjacent to each
other
so as to form a continuous elongate region with a length greater than a
specified
threshold length. The computer 70 determines the vertical distance between the
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top and bottom of the streak and compares it to the exposure time used to
capture the digital image, to determine the bitumen droplet's rise velocity.
Whichever method is used to determine the rise velocity of bitumen
droplets, the same process can be performed for bitumen droplets 82 and 82',
and a multitude of other droplets in the same pair of digital images or other
pairs
of digital images. As a result, the computer 70 determines a distribution of
bitumen droplet rise velocities in the oil sands slurry, as may be graphically
represented in Fig. 5a. The computer 70 can then predict a bitumen recovery
rate for the oil sands slurry in the PSV, by correlating the determined
bitumen
droplet rise velocities to a pre-determined predictive relationship as shown
graphically in the grade curve of Fig. 5b. In this example relationship,
bitumen
droplets having higher rise velocities indicative of larger sizes and good
aeration
are generally correlated with desirable froth formation in the PSV, and hence
higher bitumen recovery rates.
In another analysis example, the computer 70 determines the
concentration of different particulate objects in the oil sands slurry by
analyzing
information in the digital image concerning the color of the oil sands slurry.
An
example of such a digital image is shown in Fig. 6 with the colors in negative
(i.e., colors are reversed into their respective complementary colors), so
that the
water appears black, bitumen droplets appear yellow, sand grains appear green,
and other fine particles appear red or orange. The computer 70 may determine
the portion of pixels that have numerical color values associated with a range
of
red or orange tones to determine the concentration of fines in the oil sands
slurry,
or with blue tones to determine the aeration of the oil sands slurry. This
information can also be used to predict bitumen recovery rate by using pre-
determined predictive relationships.
After the computer 70 has determined the oil sands slurry characteristics,
the computer 70 may output the information to a visual display for an operator
of
the bitumen extraction process (step 160). The operator may use this
information
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to make appropriate adjustments to the process parameters to optimize bitumen
recovery or any other performance metric, to troubleshoot suboptimal bitumen
recovery, or to understand the impact of operating parameters on bitumen
recovery.
Alternatively or additionally, the computer 70 may further control one or
more components of the slurry process 31 to automatically adjust the slurry
process (step 170). For example, the computer 70 may compare the determined
slurry characteristics associated with the predicted bitumen recovery rate or
other
performance metric, to target slurry characteristics required to achieve a
target
value or range of bitumen recovery rate or other performance metric, as
determined from the a pre-determined predictive relationship. Based on this
comparison, the computer 70 may actuate components (e.g., valves, pumps,
sensors, heaters, and the like) of the oil sands extraction process to adjust
process parameters (e.g., slurry composition, flow rate, temperature) towards
the
target slurry characteristics. By using a computer 70 to rapidly analyze
images of
the oil sands slurry diverted directly from the slurry transport line, it may
be
possible to continuously adjust the process parameters in real-time response
to
changing oil sands slurry characteristics.
In addition, more than one system 10 as previously described may be
used to monitor and correlate a characteristic of an "input slurry" to a
characteristic of an "output slurry". It will be understood that the terms
"input
slurry" and "output slurry" denote slurries at relative upstream and
downstream
steps, respectively, of a process. As an example of this application, the
operator
of a PSV may wish to determine the effect of a change in feedwell design on
the
bitumen recovery rate of a PSV. However, the bitumen recovery rate depends on
the bitumen droplet rise velocity of the input slurry, which can vary with the
oil
sands feed stock. As such, unless it can be assumed that the input slurry
characteristics are the same before and after the change in the feedwell
design
(which is unlikely in practical application), the operator cannot confidently
CA 02864780 2016-07-26
attribute differences in PSV performance before and after the change in
feedwell
design to the change in feedwell design. In order to overcome this problem, a
first system 10 may be used to characterize the bitumen droplet rise velocity
of
the input slurry that is fed into the PSV, while a second system 10 is used to
characterize the bitumen content of the output slurry produced by the PSV. The
first system 10 and second system 10 may share certain components such as a
common computer 70, and may communicate with each other to correlate the
characteristic of the input slurry to the characteristic of the output slurry,
since the
effect of the input slurry on the output slurry will not necessarily be
instantaneous. Before changing the feedwell design, the first and second
systems 10 are used to monitor the characteristics of the input slurry and
output
slurry, respectively, over a range of bitumen droplet rise velocities to
generate a
first grade curve such as shown in Fig. 6b. After changing the feedwell
design,
the process is repeated to generate a second grade curve, The operator can
then quantify the change in PSV performance that is attributable to the change
in
feedwell design by comparing the first and second grade curves, for an input
slurry characterized by a given bitumen droplet rise velocity.
The previous description of the disclosed embodiments is provided to
enable any person skilled in the art to make or use the present invention.
Various modifications to those embodiments will be readily apparent to those
skilled in the art, and the generic principles defined herein may be applied
to
other embodiments. Thus, the present invention is not intended to be limited
to
the embodiments shown herein, but is to be accorded the full scope consistent
with the claims, wherein reference to an element in the singular, such as by
use
of the article "a" or "an" is not intended to mean "one and only one" unless
specifically so stated, but rather "one or more". All structural and
functional
equivalents to the elements of the various embodiments described throughout
the disclosure that are known or later come to be known to those of ordinary
skill
in the art are intended to be encompassed by the elements of the claims.
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Moreover, nothing disclosed herein is intended to be dedicated to the public
regardless of whether such disclosure is explicitly recited in the claims.
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