Note: Descriptions are shown in the official language in which they were submitted.
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PROCESS AND APPARATUS FOR TREATING A HEAVY HYDROCARBON
FEEDSTOCK
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates generally to hydrocarbon extraction and more
particularly to a process and apparatus for treating a heavy hydrocarbon
feedstock having a specific gravity differential between components of the
feedstock.
2. Description of Related Art
Heavy hydrocarbon feedstocks are generally viscous and may be entrained
with other components such as rock, sand, clay and other minerals. As a
result, heavy hydrocarbons require processing to separate useful hydrocarbon
products from residue before transport and refining.
One example of a heavy hydrocarbon ore deposit is the Northern Alberta oil
sands, which comprises about 70 to about 90 percent by weight of mineral
solids including sand and clay, about 1 to about 10 percent by weight of
water, and a bitumen or oil film. The bitumen may be present in amounts
ranging from a trace amount up to as much as 20 percent by weight. Due to
the highly viscous nature of bitumen, when excavated some of the ore may
remain as clumps of oversize ore that requires sizing to produce a sized ore
feed suitable for processing. The ore may also be frozen due to the northerly
geographic location of many oil sands deposits, making sizing of the ore more
difficult. The sized ore feed is typically processed by adding water to form a
slurry in a location proximate to the ore deposit, and the resulting slurry
hydro-
transported through a pipeline to a processing plant for separation of the
hydrocarbon products from the sand and other minerals.
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Low specific gravity hydrocarbons may be separated from sand and water, which
generally have higher specific gravity, by accumulating the feedstock in a
separation vessel and allowing gravity separation to occur. Such a separation
vessel may have a large diameter relative to side wall height and may include
a
conical bottom for sand removal. For adequate separation of hydrocarbons, the
relatively quiescent conditions of the accumulated feedstock may be required
in
the vessel, which has the adverse effect of allowing neutral density
asphaltene
mats to accumulate at an interface between the separated hydrocarbon products
and the water. These asphaltene mats accumulate as rag layers and may be
difficult to remove.
There remains a need for improved processes and apparatus for treating heavy
hydrocarbon feedstocks.
SUMMARY OF THE INVENTION
In accordance with one aspect of the invention there is provided an apparatus
for
treating a heavy hydrocarbon feedstock having a specific gravity differential
between components of the feedstock. The apparatus includes a treatment
vessel having an inlet for receiving the feedstock, a primary separation
container
located in the treatment vessel, the primary separation container being
operable
to accumulate the received feedstock to cause a low specific gravity portion
of the
feedstock to separate and rise to an upper surface of the accumulated
feedstock.
The apparatus also includes a first weir for collecting the low specific
gravity
portion from the surface of the accumulated feedstock in the primary
separation
container. The apparatus further includes a first outlet in the primary
separation
container, the first outlet being operably configured to receive settling
solids that
have separated from the feedstock that has accumulated in the primary
separation container and to produce a first discharge stream at the first
outlet.
The apparatus also includes a secondary separation container located in the
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treatment vessel to receive the collected low specific gravity portion, the
secondary separation container being operable to accumulate the collected low
specific gravity portion to cause hydrocarbon products to separate and rise to
an
upper surface of the accumulated low specific gravity portion of the
feedstock.
The apparatus further includes a product outlet for collecting hydrocarbon
products from the upper surface of the accumulated low specific gravity
portion to
produce a hydrocarbon product stream at the product outlet.
The apparatus may include a feed manifold operably configured to receive a
flow
of feedstock from the inlet and cause the feedstock to flow along the feed
manifold to the primary separation container for conditioning the feedstock
flow to
facilitate separation of the low specific gravity portion in the primary
separation
container.
The feed manifold may include a plurality of adjacently located open channels
extending between the inlet and the primary separation container, the open
channels being operable to reduce turbulence intensity in the feedstock flow.
The feed manifold may be operably configured to cause a feedstock flow into
the
primary separation container to have a Reynolds Number of about 20,000.
The primary separation container may include a downwardly inclined base
operably configured to direct settling solids in the accumulated feedstock
toward
the first outlet of the treatment vessel.
The downwardly inclined base defines a first portion of the primary separation
container and the primary separation container may further include a second
portion of the primary separation container located to receive the solids from
the
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downwardly inclined base, the first outlet being located at a low point in the
second portion of the primary separation container.
The secondary separation container may be located generally below the
downwardly inclined base of the primary separation container.
The first weir may include a catchment located behind the weir, the catchment
being operable to receive the collected low specific gravity portion and to
direct
the collected low specific gravity portion to the secondary separation
container.
The apparatus may include a conduit extending between the catchment and the
secondary separation container.
The first weir may include a weir having a J-shaped cross section.
The first weir may include a serpentine weir.
The first weir may be positioned partway along the primary separation
container
for collecting the low specific gravity portion from a first area of the upper
surface
of the accumulated feedstock in the primary separation container, the first
area
extending generally between the inlet and the first weir and the apparatus may
further include a second weir positioned in primary separation container
beyond
the first weir and defining a second area extending between the first weir and
the
second weir, the second weir being disposed to permit feedstock in the second
area from which a substantial portion of the low specific gravity portion has
been
collected to overflow to produce a second discharge stream at a second outlet.
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The apparatus may include a first launder box located to receive and
accumulate
overflowing feedstock from the second weir and the second outlet may be
located
at a low point in the first launder box.
The second discharge stream may include at least water and a fine solids
component.
The first discharge stream may include at least water and a coarse solids
component.
The first discharge stream may further include asphaltenes.
The apparatus may include a third outlet located in the secondary separation
container of the treatment vessel, the third outlet being located at a low
point in
the secondary separation container for producing a third discharge stream at
the
third outlet.
The third outlet may include a water boot disposed below the secondary
separation container, the water boot having an outlet for discharging the
third
discharge stream.
The product outlet may include a third weir located in the secondary
separation
container to cause the hydrocarbon products in the accumulated low specific
gravity portion to overflow to produce the hydrocarbon stream at the product
outlet.
The product outlet may include a second launder box located to receive and
accumulate the overflowing low specific gravity portion from the third weir
and the
product outlet may be located at a low point in the second launder box.
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The feedstock may include an added diluent and the hydrocarbon product may
include a hydrocarbon product portion and a diluent portion.
The added diluent may include one of a paraffinic diluent, and a naphthenic
diluent.
The feedstock may include at least about 60% diluent.
The treatment vessel may include a pressure containment vessel and may further
include at least one gas outlet operably configured to discharge gaseous
products
released from the feedstock during treatment.
The apparatus may include a regulator regulating an operating pressure in the
treatment vessel.
The regulator may be operably configured to regulate the operation pressure by
causing the at least one gas outlet to be activated to release gaseous
products
when the operating pressure in the treatment vessel is above pre-determined
maximum operating pressure, and introducing a supplementary pressurizing gas
when the operating pressure in the treatment vessel falls below a pre-
determined
minimum operating pressure.
In accordance with another aspect of the invention there is provided a process
for
treating a heavy hydrocarbon feedstock having a specific gravity differential
between components of the feedstock. The process involves receiving the
feedstock at an inlet of a treatment vessel, and accumulating feedstock in a
primary separation container in the treatment vessel to cause a low specific
gravity portion of the feedstock to separate and rise to an upper surface of
the
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accumulated feedstock. The process also involves collecting the low specific
gravity portion from the surface of the accumulated feedstock in the primary
separation container, and directing settling solids in the accumulated
feedstock
toward a first outlet of the treatment vessel to produce a first discharge
stream at
the first outlet. The process further involves accumulating the collected low
specific gravity portion in a secondary separation container in the treatment
vessel to cause hydrocarbon products to separate and rise to an upper surface
of
the accumulated low specific gravity portion, and collecting the hydrocarbon
products from the upper surface of the accumulated low specific gravity
portion to
produce a hydrocarbon product stream at a hydrocarbon product outlet of the
treatment vessel.
Receiving the feedstock may involve receiving a flow of feedstock at the inlet
and
causing the feedstock to flow along a feed manifold between the inlet and the
primary separation container for conditioning the feedstock flow to facilitate
separation of the low specific gravity portion in the primary separation
container.
Conditioning the feedstock flow may involve causing the feedstock to flow
along a
plurality of adjacently located open channels extending between the inlet and
the
primary separation container, the open channels being operable to reduce
turbulence intensity in the feedstock flow.
Causing the feedstock to flow along the feed manifold may involve causing a
feedstock flow into the primary separation container having a Reynolds Number
of
about 20,000, which is significantly higher than flow rates in conventional
API
separators.
Directing settling solids in the accumulated feedstock toward the first outlet
of the
treatment vessel may involve causing the solids to be directed along a
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downwardly inclined base of the primary separation container toward the first
outlet.
The downwardly inclined base may define a first portion of the primary
separation
container and the method may further involve receiving the settling solids in
a
second portion of the primary separation container located to receive the
solids
from the downwardly inclined base, the first outlet being located at a low
point in
the second portion of the primary separation container.
Accumulating the low specific gravity portion in the secondary separation
container may involve accumulating the low specific gravity portion in a
secondary
separation container located generally below the downwardly inclined base of
the
primary separation container.
Collecting the low specific gravity portion may involve overflowing the low
specific
gravity portion at a first weir disposed to receive an overflow stream from
the
primary separation container.
Collecting the low specific gravity portion may involve receiving the low
specific
gravity portion overflowing the first weir in a catchment located behind the
weir
and directing the collected low specific gravity portion to the secondary
separation
container.
Directing the collected low specific gravity portion to the secondary
separation
container may include causing the collected low specific gravity portion to
flow
through a conduit extending between the catchment and the secondary
separation container.
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Receiving the low specific gravity portion at the first weir may involve
receiving the
low specific gravity portion at a weir having a J-shaped cross section.
Receiving the low specific gravity portion at the first weir may involve
receiving the
low specific gravity portion at a serpentine weir.
Collecting the low specific gravity portion may involve collecting the low
specific
gravity portion from a first area of the upper surface of the accumulated
feedstock
and may further involve overflowing feedstock from a second area of the upper
surface from which a substantial portion of the low specific gravity portion
has
been collected to produce a second discharge stream at a second outlet of the
treatment vessel.
Overflowing feedstock from the second area of the upper surface may involve
causing the feedstock to overflow into a first launder box, the second outlet
being
located at a low point in the first launder box.
Producing the second discharge stream may involve producing a second
discharge stream including at least water and a fine solids component.
Producing the first discharge stream may involve producing a discharge stream
including at least water and a coarse solids component.
Producing the first discharge stream may involve producing a discharge stream
including asphaltenes.
The process may involve producing a third discharge stream at a third outlet
of
the treatment vessel, the third outlet being located at a low point of the
secondary
separation container.
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Producing the third discharge stream at the third outlet may involve causing
aqueous components to be collected in a water boot disposed below the
secondary separation container, the water boot having an outlet for
discharging
the third discharge stream.
Collecting the hydrocarbon products may involve overflowing the accumulated
low
specific gravity portion.
Overflowing the accumulated low specific gravity portion may involve causing
the
hydrocarbon products in the low specific gravity portion of the feedstock to
overflow into a second launder box, the product outlet being located at a low
point
in the second launder box.
The feedstock may include an added diluent, and collecting the hydrocarbon
products may involve collecting a hydrocarbon product portion and a diluent
portion.
The added diluent may include one of a paraffinic diluent, and a naphthenic
diluent.
The feedstock may include at least about 60% diluent.
The treatment vessel may include a pressure containment vessel and the method
may further involve causing gaseous products released from the feedstock
during
treatment to be discharged from the treatment vessel through at least one gas
outlet.
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The process may involve regulating an operating pressure in the treatment
vessel.
Regulating the operating pressure may involve causing the at least one gas
outlet
to be activated to release gaseous products when the operating pressure in the
treatment vessel is above a pre-determined maximum operating pressure, and
introducing a supplementary pressurizing gas when the operating pressure in
the
treatment vessel falls below a pre-determined minimum operating pressure.
In accordance with one aspect of the invention there is provided an apparatus
for
treating a heavy hydrocarbon feedstock having a specific gravity differential
between components of the feedstock. The apparatus includes a treatment
vessel having an inlet for receiving the feedstock, a primary separation
container
in the treatment vessel for accumulating feedstock received at the inlet to
cause a
low specific gravity portion of the feedstock to separate and rise to an upper
surface of the accumulated feedstock. The apparatus also includes provisions
for
collecting the low specific gravity portion from the surface of the
accumulated
feedstock in the primary separation container. The apparatus further includes
provisions for directing settling solids that have separated from the
accumulated
feedstock toward a first outlet of the treatment vessel to produce a first
discharge
stream at the first outlet. The apparatus also includes a secondary separation
container in the treatment vessel for accumulating the collected low specific
gravity portion to cause hydrocarbon products to separate and rise to an upper
surface of the accumulated low specific gravity portion. The apparatus further
includes provisions for collecting the hydrocarbon products from the upper
surface
of the accumulated low specific gravity portion to produce a hydrocarbon
product
stream at a hydrocarbon product outlet of the apparatus.
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In accordance with another aspect of the invention there is provided a process
for
treating a hydrocarbon feedstock having a specific gravity differential
between
components of the feedstock to produce a hydrocarbon product stream. The
process involves receiving the feedstock at an inlet of a treatment vessel,
and
directing the feedstock received from the inlet to flow along a downwardly
inclined
base of a primary separation container to cause solids in the feedstock to
settle to
facilitate discharging the settled solids from a first outlet of the treatment
vessel.
The process also involves accumulating the feedstock in the primary separation
container in the treatment vessel. A low specific gravity portion of the
feedstock
separates and rises toward an upper surface of the accumulated feedstock. The
process further involves collecting the low specific gravity portion from the
accumulated feedstock in the primary separation container. The process also
involves accumulating the collected low specific gravity portion in a
secondary
separation container in the treatment vessel. Hydrocarbon products separate
and
rise toward an upper surface of the accumulated low specific gravity portion.
The
process also involves collecting the hydrocarbon products from the accumulated
low specific gravity portion to produce the hydrocarbon product stream.
The process may involve in response to an operating pressure of the treatment
vessel rising above a pre-determined maximum operating pressure, causing at
least some gaseous products produced from the feedstock to be vented out of
the
treatment vessel to lower the operating pressure.
The process may involve in response to the operating pressure of the treatment
vessel falling below a pre-determined minimum operating pressure, introducing
pressurized gas to the treatment vessel, wherein the operating pressure in the
treatment vessel is raised.
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The downwardly inclined base may form a dividing wall between the primary
separation container and the secondary separation container.
At least a portion of the secondary separation container may be located below
the
downwardly inclined base of the primary separation container.
Collecting the hydrocarbon products may involve causing the hydrocarbon
products to overflow over a weir in the secondary separation container into a
launder box in communication with a product outlet of the treatment vessel.
The process may involve directing flow of feedstock from the inlet of the
treatment
vessel to a feed manifold operably configured to spread out the feedstock flow
to
reduce turbulence intensity and to provide a generally uniform feed of
feedstock
into the primary separation container.
The process may involve causing a flow rate of the feedstock to be slowed as
the
feedstock approaches a first weir of the primary separation container, the
first weir
being configured to collect the low specific gravity portion from the
accumulated
feedstock in the primary separation container.
The process may involve causing a portion of the feedstock to overflow at a
second weir downstream of the first weir to produce a discharge stream may
involve predominantly water and fine solids.
The process may involve discharging predominantly coarse solids, precipitated
asphaltenes and water from the primary separation container via the first
outlet of
the treatment vessel, and discharging predominantly fine solids and water from
the primary separation container via a second outlet of the treatment vessel.
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The process may involve discharging predominantly water from the secondary
separation container via a third outlet of the treatment vessel, and
discharging
predominantly hydrocarbon products from the secondary separation container via
a fourth outlet of the treatment vessel.
The feedstock may include heavy hydrocarbon products, water, solids, and
diluent in a proportion of 60-80% of the feedstock.
In accordance with another aspect of the invention there is provided a process
for
treating a hydrocarbon feedstock having a specific gravity differential
between
components of the feedstock to produce a hydrocarbon product stream. The
process involves receiving the feedstock into a treatment vessel containing
first
and second separation containers, and directing the feedstock received into
the
treatment vessel to flow along a downwardly inclined base of the first
separation
container to cause solids in the feedstock to settle to facilitate discharging
the
settled solids from a first outlet of the treatment vessel. The process also
involves
collecting a low specific gravity portion of the feedstock in the first
separation
container, and discharging the collected low specific gravity portion into the
second separation container. The process further involves accumulating the
collected low specific gravity portion of the feedstock in the second
separation
container. Hydrocarbon products separate and rise toward an upper surface of
the accumulated low specific gravity portion. The process also involves
discharging the separated hydrocarbon products to a product outlet of the
treatment vessel, to produce the hydrocarbon product stream at the product
outlet.
The process may involve maintaining an operating pressure of the treatment
vessel generally within a predetermined range.
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The process may involve in response to the operating pressure in the treatment
vessel rising above a pre-determined maximum operating pressure, causing at
least some gaseous products produced from the feedstock to be vented out of
the
treatment vessel to lower the operating pressure.
The process may involve in response to the operating pressure in the treatment
vessel falling below a pre-determined minimum operating pressure, causing
pressurized gas to enter the treatment vessel to raise the operating pressure
in
the treatment vessel.
The process may involve vertically stacking the treatment vessel and a second
stage treatment vessel, to treat the feedstock in stages, and configuring
interstage
feeding between the treatment vessel and the second stage treatment vessel to
occur via the force of gravity.
The process may involve receiving the hydrocarbon product stream from the
treatment vessel as an input feedstock to a second stage treatment vessel
operably configured to cause refined hydrocarbon products to be separated from
the input feedstock and discharged at a product outlet of the second stage
treatment vessel to produce a second stage hydrocarbon product stream.
In accordance with another aspect of the invention there is provided an
apparatus
for treating a hydrocarbon feedstock having a specific gravity differential
between
components of the feedstock. The apparatus includes a first treatment vessel
having a first feedstock inlet for receiving the feedstock. The apparatus also
includes a primary separation container having a downwardly inclined base,
disposed in the first treatment vessel and operably configured to receive the
feedstock from the first feedstock inlet of the first treatment vessel, to
collect a low
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specific gravity portion of the feedstock, and to discharge the collected low
specific gravity portion into a secondary separation container. The feedstock
received from the first feedstock inlet is directed to flow along the
downwardly
inclined base of the primary separation container to cause solids in the
received
feedstock to settle to facilitate discharging the settled solids from a first
outlet of
the first treatment vessel. The secondary separation container is operably
configured to accumulate the collected low specific gravity portion to cause
hydrocarbon products in the low specific gravity portion to separate and rise
toward an upper surface of the accumulated low specific gravity portion, and
to
discharge the separated hydrocarbon products via a first product outlet.
The apparatus may include a pressure regulator in communication with the first
treatment vessel, wherein the first treatment vessel includes a pressure
containment vessel.
The pressure regulator may be operably configured, in response to an operating
pressure in the first treatment vessel rising above a pre-determined maximum
operating pressure, to cause at least some gaseous products to be vented out
of
the first treatment vessel to reduce the operating pressure.
The pressure regulator may be operably configured, in response to an operating
pressure in the first treatment vessel falling below a pre-determined minimum
operating pressure, to cause pressurized gas to enter the first treatment
vessel to
raise the operating pressure.
The apparatus may include a second treatment vessel having a second feedstock
inlet for receiving a second feedstock, and a second product outlet for
discharging
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refined hydrocarbon products, the second treatment vessel being operably
configured to receive, as the second feedstock at the second feedstock inlet,
the
separated hydrocarbon products discharged from the first product outlet, the
second treatment vessel being operably configured to cause hydrocarbon
products in the second feedstock to be separated from the second feedstock and
to be discharged via the second product outlet as the refined hydrocarbon
products.
The first and second treatment vessels may be vertically stacked for treating
the
feedstock in stages, with interstage feeding between the first product outlet
and
the second feedstock inlet being configured to occur via the force of gravity.
The secondary separation container may include a weir operably configured to
collect the hydrocarbon products which rise toward the upper surface of the
accumulated low specific gravity portion.
The primary separation container may include a feed manifold operably
configured to receive a flow of the feedstock from the inlet, to spread out
the
feedstock flow to reduce turbulence intensity and provide a generally uniform
flow
of feedstock into the primary separation container, and also to facilitate
precipitation coalescence of asphaltenes in cases where the feedstock includes
a
paraffinic diluent.
An aspect ratio defined as the treatment vessel's length to the treatment
vessel's
diameter may be a ratio of about 20:7.
In accordance with another aspect of the invention there is provided a system
for
treating a hydrocarbon feedstock having a specific gravity differential
between
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components of the feedstock. The system includes a treatment vessel operably
configured for pressure containment, and having a feedstock inlet for
receiving
the feedstock, a product outlet for discharging hydrocarbon products and a
discharge stream outlet for discharging a stream includes water and solids.
The
system includes at least one separation container in the treatment vessel
operably configured to receive the feedstock from the feedstock inlet, to
accumulate a low specific gravity portion of the feedstock to cause
hydrocarbon
products in the low specific gravity portion to separate and rise toward an
upper
surface of the accumulated low specific gravity portion, and to discharge the
separated hydrocarbon products to the product outlet. The feedstock received
from the feedstock inlet is directed to flow along a downwardly inclined base
of
the at least one separation container to cause solids to settle and to
facilitate
discharging a stream includes the settled solids from the discharge stream
outlet.
The system also includes a pressure regulator in communication with the
treatment vessel and operable to regulate operating pressure within the
treatment
vessel to be within a desired range.
The at least one separation container in the treatment vessel may include a
primary separation vessel within the treatment vessel for separating out the
low
specific gravity portion from a remaining portion of the feedstock, and a
secondary
separation vessel within the treatment vessel for separating out the
hydrocarbon
products from a remaining portion of the low specific gravity portion, for
discharge
to the product outlet.
The system may include at least one of a recovery system in communication with
the pressure regulator and operable to receive and process vented gaseous
products from the treatment vessel if the operating pressure in the treatment
vessel exceeds a pre-determined maximum operating pressure, and a source of
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pressurized gas in communication with the pressure regulator and operable to
cooperate with the pressure regulator to supply gas to the treatment vessel if
the
operating pressure in the treatment vessel below a pre-determined minimum
operating pressure.
Other aspects and features of the present invention will become apparent to
those
ordinarily skilled in the art upon review of the following description of
specific
embodiments of the invention in conjunction with the accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
In drawings which illustrate embodiments of the invention,
Figure 1 is a partially cut-away perspective view of a treatment
vessel
apparatus in accordance with a first embodiment of the invention;
Figure 2 is a cross sectional view of the treatment vessel taken
along a line 2-2
in Figure 1;
Figure 3 is another cross sectional view of the treatment vessel
taken along a
line 3-3 in Figure 2; and
Figure 4 is further cross sectional view of the treatment vessel
taken along a
line 4-4 in Figure 2.
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DETAILED DESCRIPTION
Referring to Figure 1, an apparatus for treating a heavy hydrocarbon feedstock
according to a first embodiment of the invention is shown generally at 100.
The
apparatus 100 includes a treatment vessel 102 having an inlet 104 for
receiving
the feedstock. The feedstock has a specific gravity differential between
components of the feedstock.
In this embodiment the treatment vessel 102 includes a cylindrical portion 106
having first and second dome-shaped end walls 108 and 110. The cylindrical
section 106 may be fabricated from a carbon steel pipe section having a wall
thickness of about 12 mm. In other embodiments where the feedstock is
corrosive, the inside surfaces of the treatment vessel 102 may be treated to
resist
corrosion or a corrosion resistant metal may be used to fabricate the
treatment
vessel. In one embodiment the treatment vessel 102 may have a length of about
20 meters and a diameter of about 7 meters. Advantageously, fabrication of the
treatment vessel 102 may occur at an off-site location, since the aspect ratio
of the
cylindrical portion 100 would permit subsequent transport to the processing
location. In contrast, many prior art conical bottom separators must be
fabricated
on-site due to their large diameter.
The apparatus 100 also includes a primary separation container 112 located in
the
treatment vessel 102. The treatment vessel 102 is shown in cross-section in
Figure 2. Referring to Figure 2, the primary separation container 112 is
operable
to accumulate feedstock to cause low specific gravity portion of the feedstock
to
separate and rise to an upper surface 114 of the accumulated feedstock.
The primary separation container 112 also includes a first weir 116 and a
catchment 117 located behind the first weir for collecting the low specific
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gravity portion from the surface of the accumulated feedstock. The primary
separation container 112 further includes a first outlet 119 operably
configured
to receive settling solids in the accumulated feedstock and to produce a first
discharge stream at the first outlet.
The treatment vessel 102 further includes a secondary separation container
118. The secondary separation container 118 is located to receive the low
specific gravity portion collected at the catchment 117. Referring back to
Figure 1, in the embodiment shown the primary separation container 112
includes a conduit 120 having an inlet opening 122 in the catchment 117 for
receiving the collected low specific gravity portion and an outlet 124 for
discharging the collected low specific gravity portion into the secondary
separation container 118.
The secondary separation container 118 is operable to accumulate the
collected low specific gravity portion to cause hydrocarbon products to
separate and rise to an upper surface 126 of the accumulated low specific
gravity portion of the feedstock.
Referring back to Figure 2, the treatment vessel 102 further includes a
product outlet 128 for collecting the hydrocarbon products from the upper
surface 126 of the accumulated low specific gravity portion to produce a
hydrocarbon product stream at the product outlet. In this embodiment the
product outlet 128 is located in a second launder box 152 defined by a third
weir 150. The product outlet 128 is located at a low point in the second
launder box 152.
In this embodiment the treatment apparatus 102 includes a feed manifold 130,
which is operably configured to receive a flow of feedstock from the inlet 104
and to cause the feedstock to flow along the feed manifold to the primary
separation container 112. The feed manifold is operable to direct the
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feedstock flow to the primary separation container 112 while conditioning the
flow
to facilitate separation of the low specific gravity portion in the primary
separation
container.
The apparatus 100 is shown in cross section in Figure 3. Referring to Figure
3,
the feed manifold 130 includes a plurality of baffles 132 forming a plurality
of
channels 134, which receive a flow of feedstock from the inlet 104 and channel
the
feedstock flow to the primary separation container 112. In other embodiments,
the
feed manifold 130 may include a plurality of ridges for conditioning the
feedstock
flow (not shown) in place of the baffles 132.
Referring back to Figure 2, in this embodiment the primary separation
container
112 includes a downwardly inclined base 136 operably configured to direct
settling
solids in the accumulated feedstock toward the first outlet 119 of the
treatment
vessel 102. The downwardly inclined base 136 also forms a dividing wall
between
the primary separation container 112 and the secondary separation container
118.
In the embodiment shown, the first weir 116 has a generally J-shaped cross
section, which defines the catchment 117. In other embodiments apparatus 100
may include a serpentine weir. Serpentine weirs have increased length in the
path
of the flow, which increases a flow rate capacity of the weir.
The apparatus 100 also includes a second weir 142 positioned proximate the end
wall 108 and defining a first launder box 138 located to receive and
accumulate
feedstock overflowing from the second weir 142. The second weir 142 separates
the first launder box 138 from the primary separation container 112. The
apparatus 100 also includes a second outlet 146, which is located at a low
point in
the first launder box 138.
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The apparatus 100 also includes a third outlet 148 located at a low point of
the
secondary separation container 118. In one embodiment the third outlet 148
comprises a water boot.
In one embodiment the treatment vessel 102 is operably configured to operate
under a positive pressure, and the treatment vessel includes a gas outlet 154,
which is operable to discharge gaseous products released from the feedstock
during treatment. In this embodiment, the gas outlet 154 is in communication
with
first and second conduits 158 and 160 through a regulator 156 for regulating
operating pressure in the treatment vessel 102, as described later.
A further cross section through the secondary separation container 112 of the
apparatus 100 is shown in cross section in Figure 4. In Figure 4, a portion of
the
downwardly inclined base 136 is shown, and the container 118 extends from
under the downwardly inclined base to the third weir 150.
Operation
The operation of the treatment 102 is described in greater detail with
reference to
Figure 1, and Figure 2. Referring to Figure 2, a flow of heavy hydrocarbon
feedstock is received at the inlet 104 and directed to the feed manifold 130.
In
general, a flow rate of the feedstock flow may fluctuate over time.
In one embodiment the heavy hydrocarbon feedstock comprises heated and de-
aerated bitumen froth. An exemplary bitumen froth may comprise about 80%
hydrocarbon products, about 15% water, and about 5% solids. The solids may
include sand, minerals, and other fine solids. The bitumen froth may also have
an
added diluent. For example, the diluent may comprise napthenic or paraffinic
compounds, and may be present in a proportion of 60% ¨ 80% of the feedstock.
Advantageously, the configuration of the
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treatment vessel 102 provides relatively shallow accumulations in the primary
separation container 112 and the secondary separation container 118, thus
limiting the inventory of feedstock, and hence diluent, in the treatment
vessel.
Conventional diluents are generally of more value than the hydrocarbon
products being extracted and thus minimizing a diluent volume requirement is
desirable.
The feedstock components generally have a specific gravity differential that
is
sufficient to cause gravity separation under horizontal flow conditions
through
the primary separation container 112. The
hydrocarbon components
(including diluent, if added) will generally have a specific gravity of less
than
unity, while the sand and other minerals will generally have a specific
gravity
greater than unity. Fine solids, such as silt, may be largely suspended in the
water, which will have a specific gravity of close to unity.
Referring to Figure 3, the feedstock is separated into a plurality of separate
flows by the baffles 132 into the open channels 134, which spread out the
feedstock flow to provide a uniform feed into the primary separation container
112. The open channels 134 operate to reduce turbulence intensity and
.20 prevent formation of eddy currents in the feedstock flow, which would
tend to
disrupt or delay onset of gravity separation. For efficient operation of the
apparatus 100, the flow rate of the feedstock should be as high as possible,
without generating excessive turbulence in the primary separation container
112. Currents due to turbulence may work against upward movement and
separation of the low specific gravity portion of the feedstock. In one
exemplary embodiment the feedstock flow into the primary separation vessel
112 has a Reynolds number of about 20,000.
In embodiments where the feedstock includes a paraffinic diluent, the feed
manifold also conditions the stream by providing sufficient time to permit
precipitation coalescence of asphaltenes to occur.
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The feedstock entering the primary separation container 112 accumulates to a
level of the weir 116. In embodiments where the feedstock flow rate is very
high,
the weir 116 may be configured in a serpentine shape to increase a flow volume
over the lip into the catchment 117 for controlling accumulation level in the
primary
separation container 112.
Advantageously, the first weir 116 controls an
accumulation level of feedstock in the primary separation container 112,
despite
variations in feedstock flow rate at the inlet 104.
The lower specific gravity portion of the feedstock rises to the upper surface
114 of
the accumulated feedstock, while higher specific gravity sand and other
minerals
begin to settle out along the downwardly inclined base 136. The base 136 also
directs the solids along toward a portion 164 of the primary separation
container
112. In embodiments where precipitation of asphaltenes occurs, precipitated
asphaltenes are also directed along the base toward the portion 164 of the
primary
separation container 112. The a cylindrical portion 106 of the treatment
vessel
provides a rounded base in the container portion 164, which further aids in
directing solids and asphaltenes towards the first outlet 119, thus producing
a first
discharge stream as a slurry of predominantly coarse solids, asphaltenes, and
water. Advantageously, the downwardly inclined base 136 also serves to slow
down a cross sectional flow rate of the feedstock proximate the first weir
116.
The first weir 116 collects a substantial portion of low specific gravity
hydrocarbon
products in the catchment 117.
The collected low specific gravity portion is
received at the inlet 122 of the conduit 120 and directed to the secondary
separation container 118. The collected low specific gravity portion may
include
some proportion of water, since complete separation at the first weir 116 of
hydrocarbon products from water is not practically achievable due a under high
flow rate regimen.
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The first weir 116 thus collects a substantive portion of the low specific
gravity
portion of the feedstock from an area 140 between an end of the feed
manifold 130 and the first weir 116. The first weir 116 also presents a
barrier
to passage of the hydrocarbon products past the weir to an area 144 between
the first weir 116 and the second weir 142. Accordingly, the feedstock portion
overflows at the second weir 142 has relatively low hydrocarbon product
content and the first launder box 138 produces a second discharge stream
that comprises predominantly water and fine solids.
Advantageously, in this embodiment the primary separation container 112 has
a relatively shallow separation pool, which facilitates construction of the
secondary separation container 118 generally below the primary separation
container.
The low specific gravity portion collected at the first weir 116 is conducted
to
the secondary separation container 118 and accumulates to a level of the
third weir 150. As described above, the collected low specific gravity portion
comprises predominantly water and hydrocarbon product since a substantial
portion of the solids and asphaltenes are removed in the primary separation
container 112. However, mixing in the primary separation container due to
residual turbulence and a relatively short retention time under high flow
rates
may cause the collected low specific gravity portion to include at least some
proportion of water. The hydrocarbon products in the secondary separation
container 118 separate and rise to an upper surface 126 while aqueous
components are drawn off as a third discharge stream at the third outlet 148.
The third discharge stream thus predominantly comprises water, although
some sand, asphaltenes, and/or other hydrocarbon products may be
entrained in the third discharge stream.
As the collected low specific gravity portion continues to flow into the
secondary separation container 118, the hydrocarbon products will overflow at
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the weir 150 into the second launder box 152, where the hydrocarbon
products are discharged at the product outlet 128 as a hydrocarbon product
stream. The hydrocarbon product stream may comprise a significant
proportion of diluent, which may be recovered from the product stream for re-
use.
As disclosed earlier, during operation of the apparatus 100, gaseous products
may be released from the feedstock causing increased operating pressure in
the treatment vessel 102. High operating pressure may result in damage to
the treatment vessel while low operational pressure may result in the flashing
of feedstock components. The pressure regulator 156 and conduits 158 and
160 facilitate maintaining the operating pressure of the treatment vessel 102
within a desired safe range. The regulator 156 is in communication with a
source of pressurized gas (not shown) through the first conduit 158, and when
the operating pressure in the treatment vessel falls below a pre-determined
minimum operating pressure the regulator opens to allow the pressurized gas
to enter the vessel. The pressurized gas may be a relatively inert gas, such
as nitrogen, for example. Alternatively, should the operating pressure rise
above a pre-determined maximum operating pressure, the regulator 156
opens to vent gaseous products through the second conduit 160. The second
conduit may be in communication with a recovery system (not shown) for
recovering useful gaseous products or for safe disposal of the gaseous
products.
In one embodiment, two or more of the apparatus 100 may be vertically
stacked for treating the feedstock in stages, with interstage feeding
occurring
through forces of gravity.
Advantageously, the flow path through the treatment vessel 102 is free
flowing through all stages and thus the possibility of accumulating asphaltene
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mats, as described earlier, is limited by the relatively high flow rate
through
the vessel.
While specific embodiments of the invention have been described and
illustrated, such embodiments should be considered illustrative of the
invention only and not as limiting the invention as construed in accordance
with the accompanying claims.
