Note: Descriptions are shown in the official language in which they were submitted.
CA 02760896 2011-12-05
METHODS OF UPGRADING ASPHALTENE COMPOSITIONS
BACKGROUND
Pyrolysis is the chemical decomposition of organic substances carried out by
heating the
organic substances in the absence of air or oxygen. Pyrolysis reactions
typically produce three
classes of products: off gas having low heating value, potentially unstable
liquid product, and
char or residual carbon material having only a small content of hydrogen. Of
these three classes
of products, the liquid product is of the greatest value, as it can include
low-weight hydrocarbon
material that is useful as fuel or as an intermediate in the production of
fuel.
Pyrolysis technology is currently used to process various materials, including
biomass,
coal, and certain waste materials, such as spent tires. However, none of these
materials produce
a significant amount of valuable liquid material when pyrolzed. Pyrolysis of
biomass generally
produces predominantly off gas and char, with very little or no liquid
product. Pyrolysis of coal
can result in the production of about 25% liquid product, and pyrolysis of
waste materials such
as tires can produce up to 45% liquid product, neither of which is a generally
considered to be a
favorable yield.
Another common problem with pyrolysis processes used to upgrade material into
more
useful products is the tendency of the pyrolysis machinery to overly soften or
melt the material
as it enters the pyrolysis machinery. Over-softening of material being
processed through
pyrolysis machinery becomes problematic when the softened material begins to
interfere with or
jam moving parts inside of pyrolysis machinery. For example, as shown in U.S.
Pat. No.
4,439,209, a typical pyrolysis unit may comprise a rotary drum 2 into which
material to be
pyrolyzed is fed, and baffles 29 for providing satisfactory flow of the
material inside the rotary
1
CA 02760896 2011-12-05
drum 2. If excessive material softening occurs, the material may jam the
rotary drum 2, the
baffles 29, and any other moving components of the pyrolysis unit, thereby
leading the pyrolysis
unit to malfunction and break down.
SUMMARY
Disclosed below are representative embodiments that are not intended to be
limiting in
any way. Instead, the present disclosure is directed toward novel and
nonobvious features,
aspects, and equivalents of the embodiments of the methods of use described
below. The
disclosed features and aspects of the embodiments can be used alone or in
various novel and
nonobvious combinations and sub-combinations with one another.
Methods for upgrading asphaltene compositions through pyrolysis are described
herein.
In some embodiments, a method of upgrading asphaltene compositions includes a
step of
providing an asphaltene composition and a step of pyrolyzing the asphaltene
composition. The
asphaltene composition includes from 50 wt% to 90 wt% asphaltene and from 10
wt% to 50 wt%
inert material. The methods of these embodiments can lead to increased
conversion of
asphaltene molecules into valuable liquid product. The methods also tend to
avoid or mitigate
the issue of hydrocarbon over-softening within a pyrolysis unit. Additionally,
the method
provides for the upgrading of asphaltene compositions that have previously
been disposed of as
waste material, such as asphaltene recovered from by products of oil sand
processing (e.g.,
TSRU tailings).
In some embodiments, a method for upgrading asphaltene compositions includes a
step
of providing an asphaltene composition, a step of forming asphaltene pellets
from the asphaltene
composition, and a step of pyrolyzing the asphaltene pellets. The asphaltene
composition
2
CA 02760896 2011-12-05
includes from 50 wt% to 90 wt% asphaltene and from 10 wt% to 50 wt% inert
material. As with
the previous embodiments, the method results in improved conversion rates,
elimination or
mitigation of asphaltene over-softening issues, and provides methods for
upgrading asphaltene
compositions that have previously been treated as waste material.
In some embodiments, a method of preparing asphaltene pellets for use in
pyrolysis,
combustion, and other processes includes a step of providing an asphaltene
material, a step of
preparing a mixture comprising the asphaltene material and a first organic
binding agent, and a
step of extruding the mixture. In some embodiments, the first organic binding
agent is a highly
aromatic hydrocarbon, such as Aromatic 100 and Aromatic 150. In some
embodiments, the
organic binding agent is biodiesel or a fuel oil. In some embodiments the
binding agent is oil
produced from pyrolysis of the asphaltenes, thereby making a combined
pelletization and
pyrolysis process self sustaining. Asphaltene pellets formed by this method
can have good
structure retention, can be readily handled, and can serve to sufficiently
slow the softening of the
asphaltene material undergoing a pyrolysis process. Additionally, use of the
first organic
binding agent can repel water content from the asphaltene material. Without
the first organic
binding agent, attempts to remove water content from asphaltene material by
pressing the
material will can be frustrated by the asphaltene immediately reabsorbing any
repelled water.
In some embodiments, a method of preparing asphaltene pellets for use in
pyrolysis,
combustion, and other processes includes a step of providing an asphaltene
material, a step of
feeding the asphaltene material into a disc pelletizer, a step of rotating the
disc pelletizer, a step
of feeding a first organic binding agent into the disc pelletizer while the
disc pelletizer rotates,
and a step of removing asphaltene pellets from the disc pelletizer. Asphaltene
pellets formed by
this method can have good structure retention, can be readily handled, and can
serve to
3
CA 02760896 2011-12-05
sufficiently slow the softening of the asphaltene material undergoing a
pyrolysis process.
Additionally, use of the first organic binding agent can repel water content
from the asphaltene
material. Without the first organic binding agent, attempts to remove water
content from
asphaltene material by pressing the material can be frustrated by the
asphaltene immediately
reabsorbing any repelled water.
In some embodiments, a method of preparing asphaltene pellets for use in
pyrolysis,
combustion, and other processes includes a step of providing an asphaltene
material, a step of
mixing the asphaltene material with a first organic binding agent to form a
mixture, a step of
feeding the mixture into a balling drum, a step of operating the balling drum,
and a step of
removing asphaltene pellets from the balling drum. Asphaltene pellets formed
by this method
can have good structure retention, can be readily handled, and can serve to
sufficiently slow the
softening of the asphaltene material undergoing a pyrolysis process.
Additionally, use of the first
organic binding agent can repel water content from the asphaltene material.
Without the first
organic binding agent, attempts to remove water content from asphaltene
material by pressing
the material can be frustrated by the asphaltene immediately reabsorbing any
repelled water.
In some embodiments, a method of preparing asphaltene pellets for use in
pyrolysis,
combustion, and other processes includes a step of providing an asphaltene
material, a step of
mixing the asphaltene material with a first organic binding agent to form a
mixture, a step of
feeding the mixture into a briquette press, a step of operating the briquette
press, and a step of
discharging asphaltene pellets from the briquette press. The asphaltene
pellets formed by this
method can also be referred to as asphaltene briquettes. Asphaltene briquettes
formed by this
method can have good structure retention, can be readily handled, and can
serve to sufficiently
slow the softening of the asphaltene material undergoing a pyrolysis process.
Additionally, use
4
CA 02760896 2011-12-05
of the first organic binding agent can repel water content from the asphaltene
material. Without
the first organic binding agent, attempts to remove water content from
asphaltene material by
pressing the material can be frustrated by the asphaltene immediately
reabsorbing any repelled
water.
The foregoing and other features and advantages of the present application
will become
apparent from the following detailed description, which proceeds with
reference to the
accompanying figures. It is thus to be understood that the scope of the
invention is to be
determined by the claims as issued and not by whether a claim includes any or
all features or
advantages recited in this Brief Summary or addresses any issue identified in
the Background.
BRIEF DESCRIPTION OF THE DRAWINGS
The preferred and other embodiments are disclosed in association with the
accompanying
drawings in which:
Figure 1 is a flow chart detailing a method for upgrading hydrocarbon residue
as
disclosed herein;
Figure 2 is a flow chart detailing a method for pelletizing asphaltene
material as disclosed
herein;
Figure 3 is a flow chart detailing a method for pelletizing asphaltene
material as disclosed
herein;
Figure 4 is a flow chart detailing a method for pelletizing asphaltene
material as disclosed
herein; and
Figure 5 is a flow chart detailing a method for pelletizing asphaltene
material as disclosed
herein.
5
CA 02760896 2011-12-05
DETAILED DESCRIPTION
With reference to Figure 1, some embodiments of a method for upgrading
asphaltene
compositions include a step 100 of providing an asphaltene compositions and a
step 110 of
pyrolyzing the asphaltene composition.
Step 100 of providing an asphaltene composition can be achieved in a variety
of ways.
For example, the asphaltene composition can be provided by purchasing the
asphaltene
compositions from a third party. Additionally, the asphaltene composition can
be prepared by
separately acquiring the components of the asphaltene composition and mixing
the components
together in proportions described in greater detail below. In some
embodiments, the asphaltene
composition is provided by performing various refinement processes that result
in the production
of asphaltene compositions.
The asphaltene composition provided in step 100 includes an asphaltene
component and
an inert material component. Other materials may also be included in the
asphaltene
compositions, although the asphaltene component and the inert material
component will typically
make up a majority of the asphaltene composition. Additional other components
that can be
included in the asphaltene composition include sulfur scavengers and
catalysts, and are discussed
in greater detail below.
In some embodiments, the asphaltene component is substantially the only
hydrocarbon
compound included in the asphaltene composition. In such embodiments, the
asphaltene
composition can still include inert material, sulfur scavengers, catalysts,
and other materials, but
the only hydrocarbon material present in the composition is the asphaltene
component. More
specifically, the asphaltene composition can include less than 1 wt% of non-
asphaltene
hydrocarbons. This is especially true where the asphaltenes have been
precipitated from a
hydrocarbon extraction or upgrading process.
6
CA 02760896 2011-12-05
In some embodiments, the asphaltene composition includes other naturally
occurring
solid (non-toluene soluble) hydrocarbon sources, such as lignite or coal. In
some embodiments,
the solid hydrocarbon fraction is up to about 50% of the asphaltene
composition.
In some embodiments, the asphaltene composition includes from 50 wt% to 90 wt%
asphaltene and from 10 wt% to 50 wt% inert materials. When the asphaltene
composition
contains asphaltene and inert materials in this amount, the asphaltene
composition is better suited
for being subjected to pyrolysis in order to upgrade the asphaltene material
into lighter
hydrocarbon material. The presence of the inert material in these amounts
helps to ensure that
the asphaltenes do not melt when subjected to the pyrolysis process. Melting
of the asphaltene
both prevents upgrading of the asphaltene into lighter hydrocarbon molecules
and potentially
leads to the jamming or interfering of moving parts within the pyrolysis unit.
As mentioned above, suitable asphaltene compositions for use in the methods
described
herein can be obtained by performing certain refinement processes. One such
refinement process
that can produce a suitable asphaltene composition is the separation of
asphaltene material from
tailings. The tailings can be any tailings that include asphaltene material,
solvent, and inert
material. In some embodiments, the tailings are the tailings produced when
performing certain
bitumen extraction processes on tar sands and the like. In one specific
example, the tailings are
the tailings produced when performing a hot water froth treatment on tar sands
to extract
bitumen.
Separation of asphaltenes from tailings can be carried out by any known method
for
separating asphaltenes from tailings. In some embodiments, the tailings are
sent to a tailings
recovery solvent unit (TSRU), which in addition to separating solvent from the
tailings, is also
capable of separating the precipitated asphaltenes from the tailings.
Exemplary TSRU processes
7
CA 02760896 2011-12-05
are disclosed in U.S. Patent No. 7,585,407 and U.S. Published Application No.
20080156702,
both of which are hereby incorporated by reference in their entirety. The TSRU
processes can
produce a concentrated asphaltene material that includes asphaltenes and inert
materials in the
proportions described above for the asphaltene composition suitable for use in
the methods
described herein. In some embodiments, the TSRU process can be specifically
tailored to
produce a separated asphaltene composition having inert material in the
desired amount. Even to
the extent the concentrated asphaltene material produced by the TRSU does not
include
asphaltene or inert material in the desired proportion, additional asphaltenes
or inert material can
be added to the asphaltene separated during the TSRU process to reach the
desired proportion for
an asphaltene composition.
Another manner in which the asphaltene composition for the methods described
herein
can be obtained includes collecting asphaltene-containing bottoms from any of
a variety of
refinement process. In some embodiments, the refinement process is a
distillation process, such
as an atmospheric distillation process or a vacuum distillation, both of which
are processes that
produce bottoms containing asphaltene material. In some embodiments, the
bottoms produced
will require adding additional inert material or asphaltene material in order
to reach the desired
proportions for the asphaltene composition suitable for us in the methods
described herein.
The inert material present in the asphaltene composition is not limited to any
specific type or
class of inert material. Typical inert materials that can be present in the
asphaltene composition
include sand (e.g., clays quartz- and aluminosilicates), dirt, and various
types of clay, such as
kaolinite and illite.
As discussed above, the asphaltene composition can include inert material due
to the
manner in which the asphaltene composition is provided (e.g., when the
asphaltene composition
8
CA 02760896 2011-12-05
is obtained by separating asphaltene material from tailings). Alternatively or
in combination, the
inert material can be added to asphaltene material to arrive at an asphaltene
composition having
the desired percentage of each component (e.g., when certain refinery bottoms
are used as the
asphaltene component of the asphaltene composition).
The presence of the inert material helps to ensure the asphaltene material is
in a favorable
form to undergo pyrolysis inside of a pyrolysis unit. Typically, the extreme
heat used in
pyrolysis tends to soften asphaltenes. If the asphaltenes excessively soften
during the pyrolysis
step (i.e., before the end of the residency time inside the pyrolysis unit),
the asphaltene material
can begin to melt, at which point the asphaltene material may be inhibited
from breaking down
into lighter weight hydrocarbon molecules. Additionally, the softening
asphaltenes can begin to
interfere with and jam the pyrolysis unit.
The presence of inert material in the asphaltene composition can slow down the
softening
of the asphaltenes enough to prevent the asphaltenes from jamming or
interfering with the
pyrolysis unit, while at the same time not interfering with the thermal
decomposition of the
asphaltenes to produce light oil and other pyrolysis products.
As mentioned above, additional components can be present in the asphaltene
composition
besides asphaltenes and inert material. In some embodiments, sulfur scavengers
are present in
the asphaltene composition. The sulfur scavenger can be added to the
asphaltene composition
prior to pyrolysis in situations where the asphaltene composition provided by
any of the manners
described above does not include sulfur scavengers or the desired amount of
sulfur scavenger.
The sulfur scavenger can be added to the asphaltene composition to capture
hydrogen sulfide
generated during the pyrolysis reaction. Any suitable sulfur scavenger may be
added to the
asphaltene composition. Exemplary sulfur scavengers include limestone and
other alkali and
9
CA 02760896 2011-12-05
earth alkali compounds. The sulfur scavenger can be added to the asphaltene
composition in any
suitable amount. In some embodiments, the sulfur scavenger is mixed with the
asphaltene
composition at a sulfur scavenger:asphaltene composition ratio of from 1:1 to
100:1 on a weight
basis.
In some embodiments, catalyst is present in the asphaltene composition.
Catalyst can be
added to the asphaltene composition prior to pyrolysis in situations where the
asphaltene
composition provided by any of the manners described above does not include
catalysts or the
desired amount of catalysts. In some embodiments the catalyst can be naturally
occurring and
can be naturally present in some or all of the desired quantity. The catalyst
can function to
increase the rate at which the asphaltene thermally degrades into lighter
hydrocarbons during the
pyrolysis step. Any catalyst suitable for increasing the thermal degradation
of the asphaltenes
can be added to the asphaltene composition. Suitable catalysts include iron,
iron oxide, titanium
dioxide, iron titanium oxide (ilmenite), calcium titanate (perovskite), and
manganese
compounds. The catalyst can be added to the asphaltene composition in any
suitable amount. In
some embodiments, the catalyst is mixed with the asphaltene composition at a
catalyst:asphaltene composition ratio of from 1:1 to 500:1 on a weight basis.
Both sulfur scavenger and the catalyst can be included in the asphaltene
composition at
the same time. Alternatively, only one of the catalyst and the sulfur
scavenger is added to the
hydrocarbon residue.
In step 110, the asphaltene composition is pyrolyzed to form pyrolysis
products.
Pyrolyzing includes thermally degrading material in an oxygen free
environment, or in an
environment in which the oxygen content is too low for combustion or
gasification to take place.
The pyrolysis of step 110 can take place in any suitable pyrolysis unit,
including screw
CA 02760896 2011-12-05
conveyors adapted for carrying out pyrolysis. The dimensions of the pyrolysis
unit are not
limited, and can be adjusted based on the amount of material to be processed
inside the pyrolysis
unit. Other suitable pyrolysis units include, but are not limited to, a rotary
kiln, a rotary hearth
unit, and a fluidized bed unit. Specific pyrolysis units that can be used to
carry out the method
are described in U.S. Pat. Nos. 4,439,209, 4,374,704, and 4,308,103, and U.S.
Pub. App. No.
2008/0053813, each of which is herein incorporated by reference in its
entirety.
The operating conditions of the pyrolysis unit are not limited and can be
adjusted
according to the makeup of the asphaltene composition pyrolyzed therein. In
some
embodiments, the pyrolysis step is conducted at an operating temperature above
315 C (600 F),
and more specifically, within a temperature range between 350 C and 525 C. In
some
embodiments, the asphaltene composition is quickly heated to a temperature
within this range,
rather than slowly heating the asphaltene composition to a temperature within
this range. Fast
heating of the asphaltene composition can tend to result in greater liquid
product production. In
some embodiments, the asphaltene composition is heated to within the desired
temperature range
in from 400 C to 475 C.
Any suitable pressure under which pyrolysis can take place can be used inside
the
pyrolysis unit. In some embodiments, the pyrolysis step 110 is carried out in
a vacuum. When
pyrolysis step 110 is carried out in a vacuum, the pressure inside the
pyrolysis unit can range
from 1 to 100 millibar.
The residence time of the asphaltene composition inside the pyrolysis unit is
not limited,
and may be freely adjusted to accomplish higher rates of reaction. As
discussed above, the
presence of the inert material in the asphaltene composition can allow the
asphaltene
composition to remain within the pyrolysis unit for a longer period of time
because the
11
CA 02760896 2011-12-05
asphaltene composition is less likely to overly soften or melt. In some
embodiments, the
pyrolyzing step 110 is carried out for between 5 minutes and 4 hours.
The step 110 of pyrolyzing the asphaltene composition produces pyrolysis
products.
Pyrolysis products are the result of the thermal degradation of the asphaltene
material. In some
embodiments, the pyrolysis products include a liquid hydrocarbon product, a
gaseous product,
and a residual carbon product.
In some embodiments, the liquid hydrocarbon product produced by the pyrolysis
reaction
is light oil. The light oil is generally defined as hydrocarbon molecules
having a molecular
weight lower than that of the asphaltene material. In some embodiments, the
light oil produced
by the pyrolysis of the asphaltene composition has a specific gravity of less
than 0.95.
Exemplary light oils include but are not limited to naphthalene, limonene,
toluene, benzene. The
light oil can be useful as a refinery feed stock or as a feed stock to produce
various organic
chemicals and solvents.
The gaseous product that can result from the pyrolysis reaction can include an
off gas.
Exemplary off gas that can be produced by pyrolysis of the asphaltene
composition includes
hydrogen and various alkanes and alkenes, such as methane, ethane, propane,
butane, ethylene,
propylene, and butylene. In some embodiments, the off gas or gases produced by
the pyrolysis
step can be used to help generate the heat needed to drive the pyrolysis step.
For example, the
off gas can be used to generate the heat applied indirectly through the walls
of a pyrolysis unit.
In some embodiments, the off gas can be used as a natural gas additive (after
clean up).
Off gas produced by the pyrolysis reaction can also be used to produce
superheated
steam. The superheated steam produced by using the off gas can then be used in
several
additional processing steps following the pyrolysis reaction and discussed in
greater detail
12
CA 02760896 2011-12-05
below. Superheated steam is created by burning the off gas in a boiler, which
thereby produces
steam. The steam can then be sent to a processing unit where the steam is
burned and the water
vapor is superheated to a desired temperature and pressure. The superheated
steam can then be
used in any of the manners described below.
The residual carbon resulting from the pyrolysis reaction can include carbon
black. The
carbon black product can be adhered to inert material of the asphaltene
compositions. In some
embodiments, amounts of the residual carbon can be reduced and converted into
light oil
products described above through a reaction with superheated steam, such as
the superheated
steam produced using the off gas as described above. The superheated steam can
produce
hydrogen radicals which are then used to adjust the C:H ratio of the residual
carbon and form
light oil. This hydrotreating of the residual carbon will also produce
additional heat that, like the
off gas produced by the pyrolysis step, may be used to drive the pyrolysis
step.
The residual carbon can also be converted into hydrogen and carbon dioxide
using the
superheated steam. Hydrogen and carbon dioxide are formed from the reaction
between residual
carbon and superheated steam at 450 C according to the following equation:
C + 2H20 --* 2H2 + CO2 (1)
Still another use of superheated steam, whether produced using the off gas or
obtained in
another fashion, is the in situ hydrotreatment of the hydrocarbon
liquid/vapor. The in situ
hydrotreating works in part because of catalysts that are reduced in the
reductive environment in
which the pyrolysis is carried out. The superheated steam reacts with the
catalyst to re-oxidize
the catalyst, which thereby produces hydrogen. For example, when iron oxide
catalysts are
13
CA 02760896 2011-12-05
present in the asphaltene composition, the reduced iron oxide is re-oxidized
by the superheated
steam according to the following equation:
FeO(n) + H2O -> FeO(n+1) + 2H radicals (2)
The hydrogen radicals will react with broken bonds formed as a result of the
thermal degradation
of the asphaltenes and provide in situ hydrotreating.
The residual carbon produced by the pyrolysis reaction can also include inert
materials.
The residual carbon can be upgraded into a high grade carbon product through
such unit
operations as mineral flotation. In mineral flotation, the carbon reports to
the minerals
concentrate while the inert material will make up a tailings phase, which in
itself can be reused to
form more asphaltene pellets of the correct composition.
In some embodiments, the pyrolysis step 110 includes removing the gaseous
product
from the pyrolysis unit as it produced. It can be beneficial to remove the
gaseous product as it is
produced because the presence of the gaseous product in the pyrolysis unit
tends to impede
formation of liquid product. Any suitable manner of removing the gasesous
product can be used.
In some embodiments, the gaseous product is swept from the pyrolysis unit by
introducing a
steam or nitrogen purge into the pyrolysis unit. When steam is used as the
purge gas, the steam
can participate in the pyrolysis process and result in the production of more
paraffinic
components.
The method described above can further includes steps to separate certain
components
from the pyrolysis products. More specifically, the inert material, sulfur
scavenger, and/or
catalyst can all be separated from the pryolysis products. The separation
steps can be carried out
14
CA 02760896 2011-12-05
using any suitable separation methods and any suitable separation apparatus
known to those of
ordinary skill in the art. In some embodiments, the inert material is
separated from the pyrolysis
products by feeding the pyrolysis products to an attritioning and fine
screening unit operation. In
some embodiments, the catalyst is separated from the pyrolysis products by
feeding the pyrolysis
products to a magnetic or electrostatic separator. In some embodiments, the
sulfur scavenger is
separated from the pyrolysis products by feeding the pyrolysis products to a
sulfide flotation
unit. Any of the materials separated from the pyrolysis products can be reused
in the method
described herein, such as adding any of these materials to further asphaltene
compositions yet to
undergo pyrolysis.
In some embodiments, the method of upgrading asphaltenes through pyrolysis
includes
forming the aphaltene material into solid shapes, such as pellets, prior to
conducting a pyrolysis
step. Forming solid shapes of the asphaltenes prior to pyrolysis aids
transport into the pyrolysis
unit and can further prevent the asphaltenes from over-softening during
pyrolysis and possibly
jamming the pyrolysis unit. As discussed above, asphaltenes fed into a
pyrolysis unit can soften
during the pyrolysis step. If the asphaltenes soften too much, it can jam the
moving parts of the
pyrolysis unit. Accordingly, steps can be taken to alter the form of the
asphaltenes prior to its
introduction into a pyrolysis unit to thereby avoid over softening of the
asphaltene.
In some embodiments, the step of forming solid shapes of the asphaltenes prior
to
pyrolysis includes pelletizing the asphaltenes to form asphaltene pellets. The
process of forming
asphaltene pellets can be carried out using the asphaltene compositions as
described above, but
can also be carried out using asphaltenes that are not mixed with inert
material. Regardless of
whether the asphaltene composition is used in the pelletizing method,
pelletizing the asphaltenes
creates heat transfer limitations that will slow the softening of the
asphaltenes and avoid the
CA 02760896 2011-12-05
jamming of moving parts of a pyrolysis unit by the asphaltenes. However, the
pelletized
asphaltene will still be capable of thermally degrading into pyrolysis
product.
Pelletization of the asphaltenes can be accomplished according to any suitable
method for
making pellets from asphaltenes. In some embodiments, the asphaltenes are
formed into pellets
by adding water to the asphaltenes and forming a slurry, shaping the slurry
into balls or other
shapes, and drying the material. In some embodiments, the asphaltenes are
formed into pellets
by using an extrusion press or die mold to condense and shape the material
into individual units.
In some embodiments, asphaltene pellets can be produced by utilizing a
briquetting process.
Birquetting processes typically utilize two rollers with indents that material
is dropped into as the
rollers rotate in a confluent direction. In each of the above-described
methods of producing
asphaltene pellets, the size of the pellets can be manipulated and controlled
to provide the correct
size for feeding and controlling the rate of reaction in the pyrolysis unit.
In some preferred embodiments, methods of pelletizing the asphaltenes include
mixing
the asphaltenes and an organic binding agent in preparation for creating
asphaltene pellets. As
shown in Figure 2, methods of pelletizing that utilize organic binding agent
can generally include
a step 200 of providing asphaltenes, a step 210 of preparing a mixture of
asphaltenes and organic
binding agent, and a step 220 of extruding the mixture to form individual
asphaltene pellets.
In step 200, asphaltenes are provided. Any suitable asphaltenes can be used
and the
asphaltenes can be derived from any of a number of sources. In some
embodiments, the
asphaltenes are derived from oil sands or tar sands, and more specifically,
from the bitumen
content of the oil sands or tar sands. As discussed above, the asphaltenes can
also be part of the
asphaltene composition that includes inert material.
16
CA 02760896 2011-12-05
In some embodiments, the asphaltenes are asphaltenes obtained from the low
grade
bitumen product produced by solvent extraction processing performed on
bituminous material
such as oil sands. During solvent extraction, solvent is added to bituminous
material to create a
slurry. Various ratios of solvent to bitumen content in the bituminous
material (i.e., the S:B
ratio) can be used. At certain S:B ratios, asphaltene in the bituminous
material will precipitate.
The slurry produced in the solvent extraction processing can be subjected to
separation
processing to separate low grade product from high grade product. In some
embodiments, the
separation is carried out via gravity separation. The high value product
typically includes less
than 400 ppmw of solid or sediment material and less than 0.5 wt% water and
solids. This high
value product is sent into the pipelines because it has a quality
specification of water and solids
that exceeds downstream processing and pipeline transportation requirements.
The low grade
product is rich in precipitated asphaltene. In some embodiments, the low grade
product is from
90 to 95% asphaltene. The low grade product also includes a high solid (i.e.,
fines) content. As
a result, this low grade product is well suited as a source of asphaltene
material to be used in the
methods described herein.
In some embodiments, the asphaltenes are obtained from performing a
deasphalting
process on a hydrocarbon material such as bitumen. Any deasphalting process
known to those or
ordinary skill in the art can be used to obtain the asphaltenes. An exemplary
deasphalting
process includes the Residuum Oil Supercritical Extraction (ROSE) process.
In step 210, a mixture is prepared that includes the solid asphaltenes and one
or more
organic binding agents. Any suitable organic binding agents can be used to
create the mixture.
In some embodiments, the organic binding agent is a light aromatic compound.
The light
aromatic compound can be an aromatic compound having a boiling point
temperature less than
17
CA 02760896 2011-12-05
about 400 C at atmospheric pressure. In some embodiments, the light aromatic
compound used
in step 110 is an aromatic having a boiling point temperature in the range of
from about 75 C to
about 350 C at atmospheric pressure, and more specifically, in the range of
from about 100 C to
about 250 C at atmospheric pressure. In some embodiments, the light aromatic
compound has a
boiling temperature less than about 200 C.
It should be appreciated that the organic binding agent mixed with the
asphaltenes need
not be 100% organic binding agent. For example, in embodiments where the
organic binding
agent comprises one or more light aromatic compounds, the organic binding
agent can include a
mixture of aromatic and non-aromatic compounds. For example, the organic
binding agent can
include greater than zero to about 100 wt% aromatic compounds, such as
approximately 10 wt%
to 100 wt% aromatic compounds, or approximately 20 wt% to 100 wt% aromatic
compounds.
Any of a number of suitable aromatic compounds can be used as the organic
binding
agent. Examples of aromatic compounds that can be used as the organic binding
agent include,
but are not limited to, benzene, toluene, xylene, aromatic alcohols and
combinations and
derivatives thereof. The organic binding agent can also include compositions,
such as kerosene,
diesel (including biodiesel), light gas oil, light distillate, commercial
aromatic solvents such as
Aromatic 100, Aromatic 150, and Aromatic 200 (manufactured by ExxonMobil),
oxygenated
hydrocarbons, and/or naphtha. In some embodiments, the organic binding agent
is fuel oil. In
some embodiments, the binding agent is oil produced from the pyrolysis of
asphaltene pellets. In
such embodiments, a combined pelletization and pyrolysis process can be self
sustaining after
initial start up by virtue of the binding agent necessary for the
pelletization being produced from
the pyrolysis of previously formed asphaltene pellets. In some embodiments,
the organic
binding agent has a boiling point temperature of approximately 75 C to 375
C.
18
CA 02760896 2011-12-05
Any manner of preparing the mixture of organic binding agent and asphaltenes
can be
used. In some embodiments, the organic binding agent is mixed together with
the asphaltenes in
a vessel. The organic binding agent and the asphaltenes can be added into the
vessel in any
order, including simultaneously. Physical mixing of the organic binding agent
and the
asphaltenes can be carried out manually or automatedly, such as through a
motorized stirring rod
or blades. In some embodiments, the organic binder is applied as a fine spray
that partially
covers the surface of the asphaltenes as it is charged to a mixing device or
as it is rotating in a
mixing or pelletizing device.
The amount of organic binding agent and asphaltenes used when preparing the
mixture
can be any suitable amount for preparing a mixture of the two materials. In
some embodiments,
the ratio of organic binding agent to asphaltenes used when preparing the
mixture ranges from
about 1:200 to about 40:200 on a weight basis. Utilizing organic binding agent
and asphaltenes
in these ratios can help to ensure that the prepared mixture has a proper
consistency for extruding
the material and forming asphaltene pellets.
Additional materials can also be included in the mixture prepared in step 210.
One
specific example is the inclusion of inert material such that organic binding
agent is mixed with
the asphaltene composition described in greater detail above. Any of the inert
materials
described above can be mixed with the asphaltenes and organic binding agent.
In some
embodiments, the inert material is sand.
Additional materials that can be added to the asphaltenes and organic binding
agent
include, but are not limited to, catalysts and sulfur scavengers. The
additional materials can be
added to the mixture by adding the additional materials into the vessel in
which the organic
binding agent and asphaltenes are being mixed together.
19
CA 02760896 2011-12-05
Any suitable sulfur scavenger may be added to the mixture. Exemplary sulfur
scavengers
include, but are not limited to, limestone and other alkali and earth alkali
compounds. The sulfur
scavenger can be added to the mixture in any suitable amount. In some
embodiments, the sulfur
scavenger is added to the mixture at a sulfur scavenger:asphaltenes ratio of
from 5:100 to 30:100
on a weight basis.
Any suitable catalyst can be added to the mixture. Exemplary catalysts
include, but are
not limited to, iron, iron oxide, titanium dioxide, iron titanium oxide
(ilmenite), calcium titanate
(perovskite), and manganese compounds. Catalysts can be added to the mixture
in any suitable
amount. In some embodiments, the ratio of catalyst to asphaltenes ranges in
the mixture from
about 1:100 to about 5:100 on a weight basis.
Fillers may also be added to the mixture. The filler material added to the
mixture can aid
in controlling and limiting the rate of reaction. Specific examples of fillers
that can be used in
the mixture include wax and fly ash. These fillers can be added to the mixture
in any suitable
amount depending on the desired effect on the rate of reaction.
Wax can be added as a filler and/or a binder. The wax will typically be added
to the
mixture as a liquid and can serve to beneficially repel water from the
asphaltene pellets. The
wax can also aid the pyrolyzation process by adding H2 and H2-deficient
products, which thereby
reduces olefins and improves product stability. In some embodiments, the wax
is produced from
known processes that convert natural gas to liquids.
Fly ash or ground granulated blast furnace slag (GGBFS) fillers store large
amounts of
heat and also provides a large surface area for heat transfer during the
pyrolysis process. The fly
ash filler can also have a catalytic effect during the pyrolysis process. Fly
ash can include silica,
CA 02760896 2011-12-05
alumina, iron oxide, lime, and carbon. When pozzolanic fly ash is used, the
fly ash filler can
also add to the strength of the pellets.
In step 220, an extrusion process is carried out to extrude the mixture
prepared in step
210. Any suitable extrusion process that will condense and compact the mixture
can be used.
Similarly, any suitable extrusion apparatus that will produce a condensed and
compacted
extrudate can be used to carry out step 120. Where the extrusion apparatus
includes a die, the
shape of die used in the extrusion process is not limited, and can include
conventional shapes
such as circles, ovals, and rectangles, or non-conventional shapes. The shape
of the die will
generally dictate the cross section of the asphaltene pellets being formed by
the processes
disclosed herein. In some embodiments, the extrusion process is carried out a
temperature in the
range of from 10 C to 90 C.
The extruded material leaving the extrusion apparatus is generally in the form
of a rope
having a uniform cross section similar or equal to the shape of the die used
in the extrusion
apparatus. In some embodiments, this rope of extruded material is cut along
its length into
shorter segments which can ultimately serve as the asphaltene pellets. The
length of each
segment is not limited, and the rope can be cut or allowed to naturally break
into pieces of
uniform or varying length. Any suitable manner of cutting the rope along its
length can also be
used. In some embodiments, the rope has a circular cross section, and the rope
is cut along its
length at an interval that is smaller than the diameter of the circular cross
section to thereby
create disc-shaped pellets.
As mentioned above, the individual segments created after cutting the rope of
extruded
material along its length generally make up the asphaltene pellets that can
then be subjected to
upgrading, such as by pyrolysis. The shape and size of the pellets in not
limited. In some
21
CA 02760896 2011-12-05
embodiments, the die of the extrusion apparatus has a circular shape, thereby
allowing for the
formation of cylindrical asphaltene pellets. In some embodiments, the diameter
of the asphaltene
pellets is in the range of from about 0.5 to about 4 inches and the height of
the asphaltene pellets
is in the range of from about 0.25 to about 4 inches.
In some embodiments, asphaltene pellets are formed using a disc pelletizer.
More
specifically and as shown in Figure 3, the method for forming the asphaltene
pellets can include
a step 300 of providing asphaltenes, a step 310 of feeding the asphaltenes
into a disc pelletizer, a
step 320 of rotating the disc pelletizer, a step 330 of feeding a first
organic binding agent into the
disc pelletizer while the disc pelletizer rotates, and a step 340 of removing
asphaltene pellets
from the disc pelletizer.
The step 300 of providing asphaltenes can be similar or identical to the step
200
described in greater detail above. Asphaltenes can be any suitable asphaltenes
and can be
obtained from any suitable process, such as by separating precipitated
asphaltenes from tailings
produced during froth treatment of bitumen material or by deasphalting a
bitumen material. The
provided asphaltenes can also be the asphaltene composition described in
greater detail above.
In step 310, the asphaltenes are fed into a disc pelletizer. Any disc
pelletizer capable of
agglomerating material and forming pellets can be used. Generally speaking,
the disc pelletizer
will include a large pan that is positioned at an angle. The large pan is
connected to a
mechanism that is capable of rotating the pan. The disc pelletizer further
includes a port for the
continuous addition of material to be pelletized and a port where binding
agent can be introduced
into the pan. The size of the pan, the angle of inclination of the pan, and
the speed at which the
pan is rotated are all variables that can be adjusted to effect the size of
pellets formed. In some
22
CA 02760896 2011-12-05
embodiments, these variables can be adjusted during the process to alter the
type of pellet being
formed.
The asphaltenes can be fed into the disc pelletizer at any suitable location
on the disc
pelletizer for adding material into the disc pelletizer. As mentioned above,
the disc pelletizer
will preferably include a port which allows for the introduction of material
into the pan. In some
embodiments, the disc pelletizer is operated continuously, and as such, the
asphaltenes can be
added into the disc pelletizer continuously.
After the asphaltenes are fed into the disc pelletizer and the pelletizer
begins to rotate,
step 330 includes feeding an organic binding agent into the disc pelletizer.
The organic binding
agent is fed into the disc pelletizer to aid in the agglomeration of the
asphaltenes and the eventual
formation of asphaltene pellets.
The organic binding agent can be similar or identical to the organic binding
agent
described in greater detail above. Accordingly, in some embodiments, the
organic binding agent
includes an aromatic compound having a boiling point temperature in the range
of approximately
75 C to 375 C. In preferred embodiments, the organic binding agent is
Aromatic 100,
Aromatic 150, fuel oil, biodiesel, or a combination thereof.
In some embodiments, the organic binding agent is fed into the rotating disc
pelletizer by
spraying the organic binding agent into the pan. The spray of organic binding
agent can aid in
the uniform distribution of the organic binding agent throughout the pan and
improve asphaltene
agglomeration.
Any suitable amount of organic binding agent can be fed into the disc
pelletizer. In some
embodiments, the organic binding agent:asphaltenes ratio used ranges from
1:200 to 40:200 on a
weight basis.
23
CA 02760896 2011-12-05
Additional material may also be added into the disc pelletizer, either with
the asphaltenes
or as a separate feed added to the disc pelletizer. For example, a sulfur
scavenger or a catalyst
may be added to the asphaltenes. Any suitable sulfur scavenger can be used,
including, but not
limited to, limestone, alkali compounds, and earth alkali compounds. Any
suitable amount of
sulfur scavenger can be added. In some embodiments, the ratio of sulfur
scavenger to
asphaltenes ranges from about 5:100 to about 25:100 on a weight basis.
Similarly, any suitable
catalyst can be used. In some embodiments, the catalyst is selected from iron,
iron oxide,
titanium dioxide, iron titanium oxide (ilmenite), calcium titanate
(perovskite), and manganese
compounds. Any suitable amount of catalyst can be added. In some embodiments,
the ratio of
catalyst to asphaltenes ranges from about 1:100 to about 10:100 on a weight
basis.
Once the necessary materials have been added to the disc pelletizer, the
rotation of the
disc pelletizer begins to work on the material to agglomerate and form
asphaltene pellets. As
discussed above, variables such as the rotational speed of the pan, the angle
of inclination of the
pan, and the residence time can all factor into the formation of the
asphaltene pellets.
In step 340, the asphaltene pellets formed in the disc pelletizer are removed
from the disc
pelletizer. The disc pelletizer can include an exit port out of which
asphaltene pellets can be
removed. In a continuous operation (i.e., where asphaltenes and organic
binding agent are
continuously added to the rotating pan), the pellets may be removed on a
continuous basis. The
configuration of the disc pelletizer may allow for this continuous removal, as
the formed pellets
are channeled towards the exit. The exit may contain a mesh screen or device
for sizing the
pellets, so that only pellets of the required size exit the disc pelletizer.
In some embodiments, asphaltene pellets are formed using a balling drum. More
specifically and as shown in Figure 4, the method for forming the asphaltene
pellets can include
24
CA 02760896 2011-12-05
a step 400 of providing asphaltenes, a step 410 of mixing the asphaltenes with
an organic binding
agent to form a mixture, a step 420 of feeding the mixture into the balling
drum, a step 430 of
operating the ballling drum, and a step 440 of removing asphaltene pellets
from the balling drum.
The step 400 of providing asphaltenes can be similar or identical to the step
200
described in greater detail above. Asphaltenes can be any suitable asphaltenes
and can be
obtained from any suitable process, such as by separating precipitated
asphaltenes from tailings
produced during froth treatment of bitumen material or by deasphalting a
bitumen material. The
asphaltenes provided in step 400 can also be the asphaltene composition
described in greater
detail above.
In step 410, the asphaltenes are mixed with an organic binding agent to form a
mixture.
The manner of mixing the asphaltenes and the organic binding agent can be
similar or identical
to step 210 described in greater detail above. Similarly, the organic binding
agent can be similar
or identical to the organic binding agent used in step 210. Additionally, as
described in greater
detail above, the mixture can include further materials, such as sulfur
scavengers or catalysts.
After formation of the mixture in step 410, the mixture is fed into the
balling drum in step
420. Any balling drum capable of agglomerating material and forming pellets
can be used.
Generally speaking, the balling drum will include a hollow drum that is
connected to a
mechanism capable of rotating the drum about its axis. The balling drum can be
aligned
horizontally or may be inclined at an angle. The balling drum further includes
a port for the
continuous addition of material to be pelletized and a port where pellets
formed therein can exit
the balling drum.
The mixture can be fed into the balling drum according to any suitable
location on the
balling drum for adding material into the balling drum. As mentioned above,
the balling drum
CA 02760896 2011-12-05
will preferably include a port which allows for the introduction of material
into the drum. In
some embodiments, the balling drum is operated continuously, and as such, the
mixture can be
added into the balling drum continuously.
After the mixture is fed into the balling drum, the balling drum is operated
in step 430.
Operation of the balling drum generally includes rotating the drum about its
axis with the
mixture contained therein. The balling drum can begin to rotate after the
mixture is fed into the
drum, although in preferred embodiments, the drum is rotating as the mixture
is fed into the
drum.
Operation of the balling drum causes the mixture to begin to form nuclei of
asphaltene
pellets. These nuclei are small asphaltene pellets that begin to grow larger
and larger as the
balling drum continues to operate and cause interaction between the nuclei and
the free mixture
that has not yet formed into a pellet. Unlike the disc pelletizer, the balling
drum generally uses
fixed operating conditions, such as rotational speed of the drum, and will
result in a fixed size
distribution of asphaltene pellets (but not in a fixed size of pellets).
After asphaltene pellets are formed in the balling drum, a step 440 of
removing
asphaltene pellets from the drum is performed. The balling drum can include an
exit port out of
which asphaltene pellets can be removed. In a continuous operation (i.e.,
where the mixture is
continuously added to drum), the pellets may be removed on a continuous basis.
In some
embodiments, the balling drum can include a spiral screen which helps to
remove the pellets
from the drum. The mesh size of the spiral screen allows pellets of a
sufficient size to move to
the hollow shaft at the center of the spiral screen, where they are then
diverted out of the drum.
In some embodiments, the balling drum may also include a screening mechanism
for
removing small fines or undersized pellets that exit the drum with formed
product pellets. The
26
CA 02760896 2011-12-05
small fines or undersized pellets separated from the product pellets can then
be recycled back
into the drum. The screening mechanism can also separate pellets that are too
large. The
oversized pellets can then be crushed and the resulting material can be
recycled back into the
drum.
In some embodiments, asphaltene pellets are formed using a briquette press.
More
specifically and as shown in Figure 5, the method for forming the asphaltene
pellets can include
a step 500 of providing asphaltenes, a step 510 of mixing the asphaltenes with
an organic binding
agent to form a mixture, a step 520 of feeding the mixture into the briquette
press, a step 530 of
operating the briquette press, and a step 540 of removing asphaltene pellets
from the briquette
press. Asphaltene pellets formed using the above described method are also
referred to as
asphaltene briquettes.
The step 500 of providing asphaltenes can be similar or identical to the step
200
described in greater detail above. Asphaltenes can be any suitable asphaltenes
and can be
obtained from any suitable process, such as by separating precipitated
asphaltenes from tailings
produced during froth treatment of bitumen material or by deasphalting a
bitumen material. The
asphaltenes provided in step 500 can also be the asphaltene composition
described in greater
detail above.
In step 510, the asphaltenes are mixed with an organic binding agent to form a
mixture.
The manner of mixing the asphaltenes and the organic binding agent can be
similar or identical
to step 210 described in greater detail above. Similarly, the organic binding
agent can be similar
or identical to the organic binding agent used in step 210. Additionally, as
described in greater
detail above, the mixture can include further materials, such as sulfur
scavengers or catalysts.
27
CA 02760896 2011-12-05
After formation of the mixture in step 510, the mixture is fed into the
briquette press in
step 520. Any briquette press capable of forming briquettes can be used.
Generally speaking,
the briquette press will include at least two rollers with indents that rotate
in a confluent
direction. The mixture formed in step 510 is dropped into the rollers as they
rotate in a confluent
direction. The mixture can be fed into the briquette press according to any
suitable location on
the briquette press for adding material into the briquette press. Typical
briquette presses include
a funnel into which the mixture can be poured and that will guide the mixture
into the rollers. In
some embodiments, the briquette press is operated continuously, and as such,
the mixture can be
added into the briquette press continuously.
The briquette press is operated in step 530 as the mixture is fed into the
briquette press.
Operation of the briquette press generally includes rotating the rollers in a
confluent direction.
The added mixture travels between the rollers rotating in a confluent
direction and into the
indents in the rollers, which thereby compress the material into a briquette
shape.
After asphaltene pellets (i.e., briquettes) are formed in the briquette press,
a step 540 of
removing asphaltene pellets from the press is performed. In some embodiments,
the asphaltene
pellets pass through the rollers and collect in a collection area. In a
vertical configuration, the
mixture is added above the rollers, and the formed asphaltenes pellets fall
from rollers after
having passed therethrough into a collection area. The asphaltene pellets can
then be removed
from the briquette press by removing the pellets from the collection area.
Once formed, the asphaltene pellets formed by any of the methods described
herein may
be subjected to a pyrolysis process as described in greater detail above. In
some embodiments,
the above described method is modified only in that asphaltene pellets are
introduced into the
pyrolysis unit rather then introducing non-pelletized asphaltene composition
into the pyrolysis
28
CA 02760896 2011-12-05
unit. In some embodiments, additional sand or other inert material is added
into the pyrolysis
unit with the asphaltene pellets.
In some embodiments the asphaltene pellets are subjected to drying prior to
introduction
to the pyrolysis unit to reduce any residual moisture content and improve
pyrolysis. Drying of
asphaltene pellets can be by any suitable drying method, including heating or
natural solar drying
or evaporative drying through an appropriate manner of storage. In some
embodiments the
drying stage is incorporated into and part of the pyrolysis unit and the
evaporated water provides
an internal source of steam in the pyrolysis unit.
As described in greater detail above, the pyrolysis step leads to the
asphaltenes
endothermically degrading into lighter hydrocarbon products. Use of the
asphaltene pellets can
reduce or eliminate concerns of the asphaltenes quickly softening within the
pyrolysis oven and
interfering with moving parts of the pyrolysis unit. This is especially true
as the pellets formed
by the methods described herein still contain some residual moisture content
that can only be
gradually removed from the pellets as they are heating up to the oven
operating temperature.
In each of the methods described herein, the use of the organic binding agents
advantageously allows for easier water removal from the pellets prior to being
heated in a
pyrolysis unit. Traditionally, moisture content of asphaltene pellets can run
as high as 40% due
to the very open card-house structure of the asphaltene agglomerates. The
surface of these
pellets is hydrophilic, meaning that even when water is pushed out of the
pellets, the water can
be taken back up by the pellets and little to no moisture reduction will be
realized. However,
when the organic binding agents as disclosed herein are used in the formation
of the asphaltene
pellets, the asphaltene surfaces become hydrophobic and will push water away.
Consequently,
29
CA 02760896 2011-12-05
moisture removal is more easily accomplished. Specific examples of the water
expulsion
phenomenon are described in the Examples section below.
The size and shape of the pellets formed by the pelletization step are not
limited. The
shape of the pellets may be any suitable shape, including spheres, cubes, and
rods. The size of
the pellets may be any suitable size and may be selected based on the size of
the pyrolysis unit
into which the asphaltene pellets are fed.
While asphaltene pellets formed according to any of the above described
methods can be
subjected to pyrolysis processing to upgrade the asphaltene pellets, the
asphaltene pellets can
also be used in other processes. In some embodiments, the asphaltene pellets
are combusted to
produce both power and steam. Combustion of the asphaltene pellets can take
place in any
suitable combustion unit, and in some embodiments, the asphaltene pellets are
combusted in a
boiler. Any suitable type of boiler capable of combusting the asphaltene
pellets can be used. In
some embodiments, the boiler is either a pulverized fuel (PF) boiler or a
circulating fluidized bed
(CFB) boiler. Asphaltene pellets are suitable for use in these types of
boilers for similar reasons
as described above with respect to the use of asphaltene pellets in pyrolysis
units. That is to say,
the asphaltene pellets help to ensure that the asphaltenes being subjected to
combustion do not
overly soften or melt to the point that the asphaltenes plug feed tubes into
the boilers. The
asphaltene pellets, having a lower moisture content, are less likely to soften
and melt and can
therefore enter into the combustion area of the boilers and undergo combustion
for the
production of power and steam. The asphaltene pellets having lower moisture
content have a
higher heating value (BTU/lb) and lower boiling off gas requirements, thus
producing more
power per unit of asphaltene pellet and reducing the size requirement to
achieve a specified MW
power production and reducing off gas handling.
CA 02760896 2011-12-05
In some embodiments, the asphaltene pellets are subjected to drying prior to
introduction
to the boiler. The drying can be similar or identical to the drying prior to
introduction into a
pyrolysis unit as discussed in greater detail above. Drying can reduce any
residual moisture
content and improve heating value (BTU/lb). Drying of asphaltene pellets can
be by heating or
natural solar drying or evaporative drying through an appropriate manner of
storage.
When a CFB boiler is used, the asphaltene pellets preferably include limestone
as
discussed in greater detail above. The presence of limestone in the asphaltene
pellets helps to
achieve boiler fixation of sulfur as a means for flue gas desulfurization.
Examples
Example 1
360 lbs of asphaltene concentrate recovered from tailings produced during the
aliphatic
froth treatment of Athabasca tar sands is mixed together with 360 lbs of inert
sand. The mixture
of asphaltene and sand, plus 36 lbs of steam, are fed into a pyrolysis oven
operating at 450 C.
The mixture of asphaltene, sand and steam is maintained in the pyrolysis oven
for 18 minutes.
The output stream of the pyrolysis oven includes 122 lbs of gas oil, 562 lbs
of carbon black and
sand, 66 lbs of water, and 6 lbs of off gases. Sand is separated from the
output stream by feeding
the pyrolysis products to a crusher and flotation circuit.
Example 2
918 lbs of asphaltene concentrate recovered from tailings produced during the
aliphatic
froth treatment of Athabasca tar sands is mixed together with 1,000 lbs of
sand, 95 lbs of sulfur
scavenger, and 10 lbs of a silica-alumina catalyst. The mixture is fed into a
pyrolysis oven
31
CA 02760896 2011-12-05
operating at 420 C. The mixture of asphaltene and sand is maintained in the
pyrolysis oven for
17 minutes. The output stream of the pyrolysis oven includes 325 lbs of gas
oil, 1,688 lbs of
carbon black, and 10 lbs of off gases. The sand, catalyst, and sulfur
scavenger are separated
from the output stream by feeding the pyrolysis products to a crusher and
flotation circuit.
Example 3 - Extrusion Process
50 kg of asphaltene recovered from tailings produced during the aliphatic
froth treatment
of Athabasca tar sands is mixed together with 1500 cc of Aromatic 150 in a
conventional
industrial cement mixer. The Aromatic 150 is added to the asphaltene material
progressively
over a course of 5 minutes. The mixing of the Aromatic 150 and the asphaltene
material in the
cement mixer is carried out for 20 minutes to eventually produce a mixture.
The mixture is then
transported to an extrusion apparatus. The mixture is fed through the
extrusion apparatus, which
has a circular shaped die with a diameter of 1.375 inches. The extrusion
process produces a rope
of hardened and compressed material. The rope is cut along its length every
0.75 inches to
ultimately produce a plurality of disc-shaped asphaltene pellets having a
length of 0.75 inches
and a diameter of 1.375 inches.
Example 4 - Extrusion Process with Limestone
Example 3 is repeated, with the exception that a quantity of limestone is
added into the
cement mixer with the asphaltene material and the Aromatic 150. 7 kg of
limestone is added into
the cement mixer prior to the addition of the Aromatic 150. The resulting
mixture is transported
to the extrusion apparatus and disc-shaped asphaltene pellets are produced in
the same manner as
described in Example 3.
32
CA 02760896 2011-12-05
Example 5 - Disc Pelletizer
A feed material of asphaltene concentrate is provided. The asphaltene
concentrate has an
original moisture content of about 35-40%, with dried feed showing a loss upon
ignition of
-70% (at 800 C). The ash fraction (-30 wt%) of the concentrate is primarily
quartz sand and
some aluminosilicate clays. Dry concentrate contains approximately 5% sulfur,
about half as
pyrite and half as organic sulfur.
The concentrate is fed into an operating 3-ft disc pelletizer. Organic binder
is also added
into the 3-ft disc pelletizer. In one run, the organic binder is Aromatic 150.
In a second run, the
organic binder is biodiesel. The concentrate is continuously fed into the disc
pelletizer while a
fine mist of organic binder is sprayed over the concentrate as it enters the
disc pelletizer. Small
balls in the disc pelletizer are wetted by the organic binder and become
enlarged as new
concentrate added into the disc pelletizer coats the surface of the balls.
Large balls are
eventually formed, having diameters ranging from about 3/8 inches to 1 inch.
The larger balls
tend to stay on top of the smaller balls and the unballed concentrate that
remains at the bottom of
the disc pelletizer. Once the balls reach their critical size (as determined
by the disc pelletizer
speed and angle), an essentially constant pellet size is discharged over the
lip of the disc
pelletizer.
In both runs, the ratio of organic binder to moist asphaltene concentrate is
about 25:1.
Because the moist concentrate contains only about 44% LOI components at the
time of
pelletization, the ratio of organic binder to asphaltene organics is about
1:11.
While pellet feed material contained about 35-40% moisture, "wet" pellets have
a
significantly reduced moisture content of 22%, and upon further standing, the
pellets will readily
33
CA 02760896 2011-12-05
lose most of their moisture (down to <4% moisture) at ambient temperature
given dry conditions
and sufficient time.
Example 6
2,315 lbs of asphaltene concentrate recovered from tailings produced during
the aliphatic
froth treatment of Athabasca tar sands is mixed together with 100 lbs of
Aromatic 150 and then
used to make asphaltene pellets as described in Example 5. The asphaltene
pellets are allowed to
dry in ambient conditions for 24 hours. The pellets and 320 lbs of inert sand
are then fed into a
pyrolysis oven operating at 425 C. The pellets are maintained in the pyrolysis
oven for 17
minutes. The output stream of the pyrolysis oven includes 1,043 lbs of gas
oil, 1,579 lbs of
carbon black mixed with sand, and 113 lbs of off gases. The sand is separated
from the pyrolysis
products by feeding the pyrolysis products to a crusher and flotation circuit.
Example 7
In an example of water expulsion in asphaltene pellets formed by the methods
described
above, a visual inspection of the asphaltenes being sprayed with organic
binding agent in a disc
pelletizer reveals that water is being expelled from the pellets forming
therein. While the water
stays on top of the pellet surface and thereby gives the appearance of wet
material, the interior of
the pellets is, in fact, very dry. After the surface moisture is allowed to
evaporate off of the
pellets, the pellets become hard and the moisture content drops to less then
20% (as compared to
an original moisture content of more than 40%). The reduced moisture content
in the pellets
34
CA 02760896 2011-12-05
means that additional water removal steps do not need to be carried out,
resulting in a significant
cost savings.
Example 8
When carrying out the extrusion process disclosed herein, water from the feed
material
(initially about 40% moisture content) is readily expelled and a pool of water
forms on top of the
press. When the expelled water is removed from the press and a small amount of
biodiesel is
added, a very dry and solid pellet is produced having a moisture content of
around 15%. As a
contrast, the same extrusion process performed without the use of the organic
binding agent
results in most of the expelled water being sucked back into the pellet. The
result is a wet
compact that was still solid, but that includes an estimated moisture content
of about 35%.
In view of the many possible embodiments to which the principles of the
disclosed
invention may be applied, it should be recognized that the illustrated
embodiments are only
preferred examples of the invention and should not be taken as limiting the
scope of the
invention. Rather, the scope of the invention is defined by the following
claims. We therefore
claim as our invention all that comes within the scope and spirit of these
claims.
