U.S. patent application number 11/199127 was filed with the patent office on 2006-02-09 for process for producing fuel.
Invention is credited to Richard Gauthier.
Application Number | 20060027488 11/199127 |
Document ID | / |
Family ID | 35851931 |
Filed Date | 2006-02-09 |
United States Patent
Application |
20060027488 |
Kind Code |
A1 |
Gauthier; Richard |
February 9, 2006 |
Process for producing fuel
Abstract
A fuel is produced from bitumen by precipitating a substantial
portion of asphaltenes from bitumen by contacting the bitumen with
a lower alkane solvent. Suitable burners include a fluidized bed
boiler, a circulating fluidized bed boiler and a pitch boiler which
utilize either pre-combustion sulfur sorbents or post-combustion
flue gas desulfurization. The sulfur in emissions can be used to
produce sulfuric acid. The process uses a low cost fuel, generates
steam, power and sulfuric acid and meets all emission requirements
for SO.sub.2, NO.sub.x and PM.
Inventors: |
Gauthier; Richard;
(Longueuil, CA) |
Correspondence
Address: |
GEORGE A. SEABY;SEABY & ASSOCIATES
250 CITY CENTRE AVNUE
OTTAWA
ON
K1R6K7
CA
|
Family ID: |
35851931 |
Appl. No.: |
11/199127 |
Filed: |
August 9, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60599575 |
Aug 9, 2004 |
|
|
|
Current U.S.
Class: |
208/309 ; 208/39;
208/45 |
Current CPC
Class: |
C10L 5/00 20130101; C10L
5/363 20130101; C10G 1/04 20130101; C10G 21/003 20130101 |
Class at
Publication: |
208/309 ;
208/045; 208/039 |
International
Class: |
C10C 3/08 20060101
C10C003/08 |
Claims
1. A process for producing and using fuel from bitumen comprising
the steps of (a) precipitating a substantial portion of asphaltenes
from bitumen by contacting the bitumen with a lower alkane solvent;
(b) using precipitated asphaltenes as a fuel in a boiler to
generate high pressure steam and power; and (c) cleaning emissions
from the boiler to remove sulfur, NO.sub.x and PM therefrom.
2. The process of claim 1, wherein a gas and oil fraction of the
bitumen is flashed out prior to step (a).
3. The process of claim 1, wherein the bitumen is dehydrated and
desalted.
4. The process of claim 1, wherein the asphaltenes are liquid.
5. The process of claim 4, wherein the liquid asphaltenes are
pumpable.
6. The process of claim 1, wherein the lower alkane solvent is
selected from the group consisting of n-butane, n-pentane,
n-hexane, n-heptane and mixtures thereof.
7. The process of claim 6, wherein the lower alkane solvent is
n-butane.
8. The process of claim 6, wherein the lower alkane solvent is
n-pentane.
9. The process of claim 1, wherein the precipitated portion of
asphaltene is from 5 to 40% w/w of the bitumen.
10. The process of claim 8, wherein the precipitated asphaltene is
from 15 to 25% of w/w of the bitumen.
11. The process of claim 1, wherein a portion of a resin in the
bitumen is precipitated with the asphaltenes.
12. The process of claim 11, wherein the resin is less than 10% w/w
of the bitumen.
13. The process of claim 1, wherein the high pressure steam is used
to produce electricity and steam for use in an oil sands extraction
process.
14. The process of claim 13, wherein said oil sands extraction
process is a steam assisted gravity drainage, or a cyclic steam
stimulation process.
15. The process of claim 1, wherein the boiler is a fluidized bed
boiler.
16. The process of claim 15, wherein the boiler is a circulating
fluidized bed boiler.
17. The process of claim 16, wherein sulfur is removed from the
boiler emissions using limestone or lime as a sulfur absorbent
during combustion, by flue gas desulfurization or by a scrubber
during post-combustion sulfur removal.
18. The process of claim 15, wherein the boiler uses a device to
produce sulfuric acid to remove SO.sub.2 emissions.
19. The process of claim 2, wherein the flashed out gas and oil
fraction is mixed with de-asphalted oil obtained in step (a) to
yield an upgraded de-asphalted oil of a lower viscosity, and lower
density.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority on U.S. Provisional
Application 60/599,575 filed Aug. 9, 2004.
FIELD OF THE INVENTION
[0002] This invention relates to a process for producing fuel from
bitumen.
[0003] More specifically, the invention relates to an integrated
process in which heavy oil or bitumen produced from both "in situ"
or surface oil sands mines is solvent de-asphalted to yield a
de-asphalted oil and an asphaltene fraction, which is used as fuel
in a boiler to replace expensive natural gas, reduce energy costs
and reduce or obviate the need for diluents to make the
de-asphalted oil pipelinable. In particular the invention will
substantially reduce energy and diluent costs and improve the
economics of producing bitumen. In addition, produced de-asphalted
oil will be of higher quality, lower viscosity, reduce sulphur,
nitrogen, Conradson carbon, nickel and vanadium.
BACKGROUND OF THE INVENTION
[0004] Since Canadian conventional oil production is dwindling and
both synthetic crude and bitumen production are on the rise there
is a need to reduce the energy costs of bitumen production and the
use of expensive diluents for transporting bitumen to refineries by
pipeline.
[0005] As conventional oil deposits dwindle, upgradable fuel
derived therefrom has become increasingly more expensive to
produce. The search for inexpensive fuel sources is an on-going
problem. Bitumen or tar sand deposits (oil sands) found in areas of
Western Canada such as the Athabasca, Cold Lake and Peace River
areas of Alberta, and other places in the world (Venezuela, U.S.A.,
China, Russia) represent a largely unused source of raw crude oil,
typically in the form of bitumen. The bitumen is produced from
either oil sands (surface mines) or "in situ" by steam assisted
gravity drainage "SAGD", cyclic steam stimulation "CSS" and other
production techniques using steam. The bitumen from oil sands or in
situ production includes a mixture of maltenes, aromatics, resins
and asphaltene compounds in varying amounts, the least valuable
component being the asphaltenes. Extracting bitumen from oil sands
and other deposits is difficult and requires hot water or steam
injection to liquefy the high viscosity bitumen for transport to a
surface processing plant. The process of steam production requires
continuous use of often expensive fuels and thus an inexpensive,
readily available fuel is highly desirable.
[0006] Several processes have been described addressing the
above-identified problems including those described, e. g. in U.S.
Pat. Nos. 6,536,523; 6,524,469; 6,511,937; 6,357,526; 5,055,029;
4,755,278; 4,634,520; 4,283,231; 4,042,027 and 4,036,732.
[0007] The processes described in the prior art suffer from a
number of important drawbacks. The processes are complex, involving
multiple separate steps, which are not fully integrated. Moreover,
the processes involve pre-treating the bitumen which may be
expensive, requiring many reagents and diluents, specialized
equipment and prior manipulation of the crude bitumen. None of the
processes offers an affordable solution to the reduction of
production costs of heavy oil producers who rely on expensive fuel
such as natural gas to generate the high pressure steam needed to
extract the low viscosity bitumen found in different places such as
in the Athabasca region of Alberta, Canada. Existing processes do
not meet the need for reduced fuel and diluent dependency in the
production of a partially upgraded bitumen stream and a precipate
of asphaltenes. Asphaltenes are low value hydrocarbons useful as a
fuel in the field. The removal of the heavier portions of the
bitumen does improve the viscosity of the de-asphalted oil and
accordingly a much lower amount of expensive diluents is needed to
make the produced bitumen pipelinable to the market.
[0008] Thus there is a need for an improved process for generating
fuel from bitumen to reduce energy cost and use of expensive
diluents.
SUMMARY OF THE INVENTION
[0009] Accordingly, the present invention relates to a process for
producing fuel from bitumen comprising the step of: flashing the
gas oil fraction out of bitumen, de-asphalting the bitumen, and
precipitating a substantial portion of the asphaltenes from bitumen
by contacting the bitumen with a lower alkane solvent.
[0010] The inventor discovered that unprocessed bitumen (from both
from oil sands and "in situ"" processes can be efficiently
de-asphalted to produce higher quality de-asphalted oil and
asphaltenes which can be used as a liquid or solid fuel for
producing steam. The bitumen is merely dehydrated and desalted,
flashed to remove the gas oil fraction and then de-asphalted. The
process is cost effective and produces high quality fuel, that is
of higher BTU (British Thermal Unit) content than coal or pet coke
with lower amounts of ash than coal. These characteristics make
asphaltenes an ideal fuel to be transported in solid form as
granules, or in hot liquid form, or as a water slurry or as a water
or oil emulsion. Moreover, fluidized bed boiler, BFD (bubbling
fluidized bed), CFB circulating fluidized bed or OTSG (once through
boiler, CFB boilers) or OTSG boiler with FGD (flue gas
de-sulfuration) units burn asphaltenes in a clean manner and
generate much less emissions than coal. Alternatively the boilers
can be used either with a sulfuric acid plant or preferably with a
SNOX.TM. or WSA.TM. unit for cleaning emissions of SO.sub.2,
NO.sub.x and PM while producing commercial grade, sulfuric acid.
Removing SO.sub.2, NO.sub.x and PM in the gas phase after
combustion has additional benefits: reduced needs for sulfur
sorbents, reduced production of ashes and gypsum, improved thermal
efficiency of boiler. In addition the removal of polluants allows
for the production of sulfuric acid of commercial grade; the most
common and basic chemical.
[0011] Moreover, the process is fully integrated and can be used on
site without the need for additional processing units. Since the
process uses raw, unprocessed bitumen, it significantly decreases
costs by reducing the amount of pretreatment with organic solvents.
The process of the present invention significantly improves oil
quality, and significantly lowers oil viscosity thereby permitting
easier pumpability of the oil through standard pipelines. Organic
and inorganic contaminants are reduced in the oil which improves
the value of the de-asphalted oil.
[0012] In accordance with the present invention, there is provided
a process for producing fuel from crude bitumen including the steps
of precipitating a substantial portion of asphaltenes from bitumen
by contacting the bitumen with a lower alkane solvent to yield an
asphaltene fraction and a de-asphalted oil fraction essentially
free of asphaltenes which can be processed further, upgraded or
mixed with diluent for shipment to market.
[0013] The asphaltenes fraction can be injected while hot into a
fluidized bed boiler, preferably an OTSG CFB (once through
circulating fluidized bed boiler) where combustion occurs in the
presence of a sulfur absorbent such as limestone and/or lime to
remove sulfur.
[0014] The boiler is used to generate high pressure steam that will
first go through a steam turbine to generate electricity and steam
for an SAGD, CSS or low pressure oil sand process.
[0015] Once through the turbine, the steam can be extracted at a
back pressure needed for use in a SAGD, CSS or OILSANDS or other
steam extraction process which may be developed in the future.
[0016] The asphaltenes fraction can be used as a hot liquid in the
combustion process or alternatively can be pelletized for storage,
transport or use as a solid fuel in the combustion step.
Alternatively, hot liquid asphaltenes can be mixed with various
surfactants and solvents to obtain a liquid fuel similar to bunker
"C" fuel or residual fuel that can be stored, transported, pumped
and used in the combustion process. The process can use coal,
bottom of the barrel residues or petroleum coke stored on the site
of oil sands mines as fuels for boilers. Logistics and costs will
dictate which fuel or combination to be used, because fluidized bed
boilers are fuel flexible.
[0017] Fluidized bed boilers can be replaced by downshot boilers if
petroleum coke is used as fuel, or pitch boilers if the asphaltenes
stream is used as fuel. In both cases, a sulfuric acid plant to
remove SO.sub.2 and NO.sub.x will be required to meet emission
requirements.
[0018] Alternatively, steam can be used directly in SAGD, CSS pads
without the need to cogenerate power.
[0019] Alternatively, the CFB boiler can operate without the
addition of limestone or lime sorbent. Instead of producing gypsum
a sulfuric acid plant or SNOX.RTM. or other process know to the art
to remove sulfur can be used for the back end. The benefits will be
reduced cost for limestone, higher thermal efficiency and better
emissions, since 95-98% of both SO.sub.2 and NO.sub.x will be
removed. Prior processes failed to include the production of
sulfuric acid as an efficient way to meet emissions requirement for
SO.sub.2, NO.sub.x and PM. The use of a sulfuric acid plant at the
back end allows for higher thermal efficiency of the boiler,
reduced need for limestone and reduced production of gypsum. In
northern Alberta transportation costs are high, the use of
limestone is expensive and production of gypsum increase costs. The
production of marketable sulfuric acid disposes of sulfur in the
most economical and permanent manner. No stockpiles of sulfur or
gypsum will be created as a result of this invention. The use of a
sulfuric acid plant makes it possible to remove SO.sub.2 NOX and PM
without using water. The added benefit of not using limestone and
making sulfuric acid instead of gypsum makes the water chemistry
much simpler, because the pH of water is not affected by limestone
and other contaminants. The resulting ash from the sulfuric acid
process is water free and totally inert so that they can be
disposed of safely.
DETAILED DESCRIPTION OF THE INVENTION
[0020] As used herein, the term "lower alkane" when used in
connection with a solvent refers to a branched or straight chain
acyclic alkyl group containing four to about ten carbon atoms,
preferably four to about seven carbon atoms, and preferably five
carbon atoms. Examples of suitable solvents include n-butane,
iso-pentane, n-pentane, n-hexane, n-heptane, and mixtures
thereof.
[0021] Crude bitumen can come from many sources, examples of which
include in situ SAGD (steam assisted gravity drainage) pads,
surface mines. The present invention uses raw bitumen produced from
either SAGD pads or CSS (cyclic steam stimulation) steam flooding
or bitumen obtained from froth treatment at oil sands mines.
Alternalively the present invention uses coal, petroleum coke from
stored pads or existing or future cokers located at upgraders or
refinery sites.
[0022] It is well known by those skilled in the art that crude
bitumen removed from SAGD pads and the like contains water and salt
which must be removed before further processing. Many dehydration
and desalting processes are known, such as that disclosed U.S. Pat.
No. 6,536,523, the contents of which are hereby incorporated by
reference. The salt content post desalting is typically 0.01%
w/w.
[0023] The heavy oil or bitumen is flashed to remove the gas on
fraction that will be mix with the de-asphalted fraction. The
residue will enter the de-asphalting step, the lower alkane
solvents are mixed with the crude bitumen so that asphlatene
precipitates and separates from de-asphalted oil (DAO). Typically,
the solvents are used alone, but may be used as mixtures
thereof.
[0024] The lower alkane solvents iso-pentane, n-pentane and hexane
are usually selected, because during de-asphalting they are
efficient at removing a large portion of the asphaltene and small
portion of resin components, but do not remove all of the resin
components, which are typically found in suspension, together with
maltenes and aromatic compounds in the crude bitumen.
[0025] The portion of asphaltene separated is typically 10-20% w/w
of crude butimen, and the amount of precipitated resins is between
15 and 25% w/w of the total amount of the asphaltenes precipitated
or 5-10% of ww of the initial bitumen. Typically the amount of
precipitated asphaltene is 15-20% w/w of the bitumen and more than
90% of the asphaltenes present in the crude oil. A small amount of
resins will also be precipitated along with the asphaltenes.
[0026] For asphaltenes that are useful in roofing and the like, or
indeed for transportation, a small amount of resin in the
asphaltene is desirable. Therefore, a portion of the resin
component may be co-precipitated with the asphaltene. Typically,
the portion of the resin is less than 10% w/w. For co-precipitating
the resin component, n-butane is typically the chosen lower alkane
solvent, which is mixed with another of the lower alkane
solvents.
[0027] Typically, the precipitation step takes place in a
de-asphalting unit such as a ROSE.TM., SOLVAHL.TM., DEMEX.TM. or a
similar unit, the operation of which is known to those skilled in
the art.
[0028] The asphaltene exits the de-asphalting unit as a hot liquid
and is fed to a combustion unit. In order, to ease handlability,
the hot asphaltene can be pelletized or mixed with water to form an
emulsion. Alternatively, hot asphaltene can be mixed with
dispersants and solvents to yield an oil based emulsion.
[0029] The combustion unit can be a standard benson type boiler
such as a once-through steam generator boiler (OTSG). More
specialized combustion units include a circulating fluidized bed
boiler (CFB), a bubbling fluid bed boiler (BFB) a fluidized bed
boiler (FB) or an OTSG CFB boiler. Alternatively the combustion
units can be a standard drum type of boiler that will produce 100%
quality steam and cost less to purchase than OTSG (once through
steam generating units). Water quality will be an issue that will
be solved by using higher quality water treatments such as ZLD
(zero liquid discharge) or other techniques known to the art.
[0030] Depending upon which combustion unit is chosen, a number of
further processing steps can take place. With the Benson boiler,
burning the asphaltene produces toxic flue gases such as sulfur
dioxide. Typically, the Benson boiler or O.T.S.G. has a flue gas
desulfurization (FGD) unit attached thereto which mixes the sulfur
dioxide with hydrogen to produce less toxic hydrogen sulfide.
Alternatively a scrubber unit may be use to remove sulfur. With
fluidized bed boilers, limestone and lime may be added to produce
commercially useful gypsum. Typically, the combustion units use
available sources of fuel, such as petroleum coke or coal.
[0031] According to an alternative embodiment of the present
invention, de-asphalted oil is produced from crude bitumen by the
steps of:
[0032] (a) salt and water is removed through dehydratation &
water removal in process known by those skilled in the art.
[0033] (b) the dehydrated and desalted bitumen is flashed the
remove the gas oil fraction in process know by those skills in the
art.
[0034] (c) removing asphaltenes from bitumen by contacting the
bitumen with a lower alkane solvent; and
[0035] (d) removing a substantial portion of de-asphalted oil "DAO"
produced in step (c), the DAO oil being substantially free of
asphaltenes.
[0036] (e) Adding the flashed out gas oil fraction obtained in step
(B) to the DAO de-asphalted oil fraction of step D that will be of
lower viscosity, higher quality than the original bitumen.
[0037] The residual de-asphalted oil (DAO) may be further processed
by adding diluents such as natural gas liquid "NGL" or other liquid
diluant or synthetic crude which improves the pumpability of the
DAO and increases its accessibility to oil pipelines. As another
option, the DAO may be further upgraded by dewaxing and
deacidifcation (so called total acid number (TAN) removal). The
resulting upgraded DAO has substantially improved viscosity,
typically less than 350 cSt, which improves pumpability of the DAO
without the need of diluents. Table 1 summarizes the pipeline
specifications as of June 2004 for crude oil in Alberta.
TABLE-US-00001 TABLE 1 Density @ 15.degree. C. 940 kg/m.sup.3 (RVP)
Reid Vapor Pressure 103 kPa Viscosity @ 11.degree. C. 350
mm.sup.2/s or cSt (BS & W) Bottom Sediment & Water 0.5% v/v
Bromine number 10 gr BR.sub.2/100 gr Olefin content 1.0% v/v
[0038] An important aspect of the present invention is the low cost
generation of electricity for use on a site or for sale to the
electricity grid. To this end, the invention provides a process for
generating steam, which comprises feeding asphaltenes to a
fluidized bed boiler where it is burned in an upward flow of
combustion air. Fuel ash and unburned fuel carried from the furnace
are collected by a solids separator and returned to bottom of the
furnace. Limestone is used as a sulphur sorbent which is also fed
to the bottom of the furnace. Furnace temperature is maintained in
the range of 1500-1700 of using a suitable heat absorbing surface.
The combustion process allows for: [0039] fuel flexibility because
the relative low furnace temperatures are below the ash softening
temperature for nearly all fuels allowing a given furnace to handle
a wide range of fuels [0040] low SO.sub.2 emissions because
limestone is such an effective sulphur sorbent in the 1500-1700 of
temperature range, SO.sub.2 removal efficiency for CFB is 95% and
higher, [0041] low NO.sub.x emissions, because the low furnace
temperature and combustion temperature plus the staging of air feed
to the furnace produce very low NO.sub.x emissions, and [0042] high
combustion efficiency in the furnace because the long solids
residence time plus the vigorous solid gas contact and sanding
caused by the fluidized airflow result in a high combustion
efficiency even with fuels which are difficult to burn. [0043]
During the combustion of asphaltenes and the sulphur contained
therein the following reactions occur when limestone is injected
into the furnace. [0044] oxidation of sulphur S+O.sub.2=SO.sub.2
[0045] limestone is calcinated to form calcium oxide
CaCO.sub.3=CaO+CO.sub.2-425 Kcal/kg (of CO.sub.3) [0046] sulfur
dioxide reacts with solid CaO: SO.sub.2+1/2O.sub.2+CaO=CaSO.sub.4
(solid)+3740 Kcal/kg (ofs)
[0047] The resulting calcium-sulphate (gypsum) based ashes are
chemically stable and easily disposed. This ash can be used as a
raw material for cement manufacturing, soil stabilisation, or road
based or store in pads.
[0048] The steam produced can be fed into a steam turbine to
generate electricity to be sold to an electricity supplier.
Alternatively, the process may be circular such that the steam
generated may be fed back into the SAGD pads to aid removal of oil
sands therefrom.
[0049] Another lower cost alternative to limestone as sulfur
sorbent consists of using either standard boilers or fluidized bed
boilers to burn the high sulfur fuel in the most efficient manner,
and to connect the boiler to a sulfuric acid plant to clean up and
remove the SO.sub.2 and NO.sub.x in the gas phase. The inventor
discovered that removing the pollutants (SO.sub.2, NO.sub.x, PM)
following combustion provides more flexibility, reduce emissions of
SO.sub.2, NOx and PM, and increased boiler efficiency by 15-20%
compared to others technologies. The results of this alternative
combustion process: [0050] fuel flexibility because the relative
low furnace temperatures are below the ash softening temperature
for nearly all fuels allowing a given furnace to handle a wide
range of fuels [0051] low SO.sub.2 emissions because up to 98%-99%
of SO.sub.2 is removed. [0052] low NO.sub.x emissions because the
low furnace temperature and combustion temperature plus the staging
of air feed to the furnace produce very low NO.sub.x emissions. In
addition the denox step remove 95% of NO.sub.x [0053] high
combustion efficiency in the furnace because the long solids
residence time plus the vigorous solid gas contact and sanding
caused by the fluidized airflow result in a high combustion
efficiency even with fuels which are difficult to burn fuels.
[0054] High thermal efficiency as sulphuric acid production is
endothermic
[0055] As embodiment for this invention the combustion of
asphaltenes and the sulphur contain therein, the following reaction
occur when combustion of sulphur compound in a furnace equipped
with WSA/SNOX.TM. plant TABLE-US-00002 Combustion H.sub.2S + 3/2
0.sub.2 .fwdarw. H.sub.2O + SO.sub.2 + Kj/mole Decomposition
H.sub.2SO.sub.4(liq.) + "HC" + 0.sub.2 + q .sub..fwdarw. SO.sub.2 +
.sub.XCO.sub.2 + .sub.YH.sub.2O Oxidation SO.sub.2 + 1/2 0.sub.2
.fwdarw. SO.sub.3 + 99 kJ/mole Hydration SO.sub.3 + H.sub.2O
.sub..fwdarw. H.sub.2SO.sub.4 (gas) + 101 kJ/mole Condensation
H.sub.2SO.sub.4 (gas) + 0.17 H.sub.2O (gas) .sub..fwdarw.
H.sub.2SO.sub.4(liq.) + 69 kJ/mole DENOX NO + NH.sub.3 + 1/4
0.sub.2 .fwdarw. N.sub.2 + 3/2 H.sub.2O + 401 kJ/mole
The gas then enters the reactor, which contains one, two or more
catalyst beds, depending on the SO.sub.2 content and the desired
degree of conversion. Since reaction in the reactor is exothermal
the gas is cooled between the beds in order to favourize the
SO.sub.2/SO.sub.3 equilibrium. After the last conversion stage the
gas is cooled, whereby the SO.sub.3 reacts with the water vapour to
form gas phase sulphuric acid as shown above.
[0056] In Northern Alberta the distances make transportation of
limestone expensive and the production of gypsum and waste water
problematic from an environmental point of view.
[0057] This invention allows the use of low cost fuels, to burn in
the most efficient manner, producing steam and power and meeting
the most stringent emissions norms. A sulfuric acid plant helps
reduce SO.sub.2 by 99%, NO.sub.x by 95-97% and PM by 99%, and
improves thermal efficiency from 34-36% to 41-44%, because
production of sulfuric acid is endothermic.
[0058] Higher efficiency means reduced fuel use, and reduced
emissions since less fuel is burned. In addition, the use of water
is reduced to zero and the production of ashes and gypsum is
reduced by 60-80%. The ashes are inert and do not interfere with
the water chemistry of oil sands tailings.
[0059] An integrated system for carrying out the process of the
invention includes a dehydration/desalting unit for receiving the
crude bitumen from oil sands, and dehydrating and desalting the oil
sand before transporting to a de-asphalting unit. Optionally, if
the oil sand is received from oil sand plants, it may already be
dehydrated and desalted and thus may be fed directly into the
de-asphalting unit. Typically, the de-asphalting unit is a ROSE.TM.
unit or other known commercial apparatus for de-asphalting oil
using a lower alkane solvent or more typically a mixture of lower
alkane solvents for precipitating a substantial portion of
asphaltene from bitumen.
[0060] A combustion unit in the form of a boiler such as described
above burns the asphaltene to generate steam, which may be fed to a
steam turbine. The process is cyclical and permits the steam
turbine to pump steam directly into SAGD or CSS pads to remove
crude bitumen therefrom to begin the cycle again.
[0061] Another aspect of the present invention is a burnable fuel
composition produced by the process of the present invention. The
fuel composition comprises a liquid asphaltene substantially free
of de-asphalted oil and resins. The asphaltene oil composition has
the properties set out in Table 2. TABLE-US-00003 TABLE 2
Asphaltene DAO Steam properties Yield (% w/w) 5-40%, preferably
15-25% 60-95%, preferably and typically 19% 75-85% and typically
81% Specific gravity @ Preferably 1.05-1.20, Preferably 60.degree.
F. typically, 1.140 0.940-0.995, typically, 0.985 API* Gravity
Preferably -9--4, Preferably 13-22, typically, -7.4 typically 15.1
Nitrogen (% w/w) Preferably 0.30-1.0, Preferably 0.05-0.5,
typically, 0.61 typically, 0.19 Sulfur (% w/w) Preferably 5-10,
Preferably 1-5, typically, 7.0 typically, 3.6 Conradson Carbon
Preferably 30-60, Preferably 1-10, (% w/w) typically, 44 typically,
5.2 Nickel (wppm**) Preferably 200-800, Preferably 30-50,
typically, 560 typically, 40 Vanadium (wppm**) Preferably 200-800,
Preferably 25-50, typically, 670 typically, 35 Viscosity cSt @
210.degree. F. Preferably 20-40, typically, 31 cSt @ 275.degree. F.
Preferably 5-20, typically 9 cSt @ 400.degree. F. Preferably
30-49,000, typically 44,900 cSt @ 550.degree. F. Preferably
150-225, typically, 203 R&B (Ring & Ball) 350 Softening
Point (.degree. F.) *American Petroleum Institute **weight in parts
per million
[0062] In another aspect of the present invention, high quality
pumpable de-asphalted oil is produced. The high quality DAO is
asphaltene free and has the properties listed in Table 3.
[0063] Table 3 lists the ROSE.TM. yield and quantity from the
process of the invention using Whole Cold Lake bitumen, and
n-pentane as the de-asphalting solvent. TABLE-US-00004 TABLE 3
Feed.sup.1 Asphaltene DAO.sup.2 Steam properties Yield (% w/w) 100
19 81 Yield (% v/v) 100 17 83 Specific gravity @ 0.994 1.140 0.965
60.degree. F. API Gravity 10.9 -7.4 15.1 Nitrogen (% w/w) 0.27 0.61
0.19 Sulfur (% w/w) 4.3 7.0 3.6 Conradson 12.6 44 5.2 Carbon (%
w/w) Nickel (wppm) 137 560 40 Vanadium 155 670 35 (wppm) Viscosity
cSt @ 210.degree. F. 113 31 cSt @ 275.degree. F. 23 9 cSt @
400.degree. F. 44,900 cSt @ 550.degree. F. 203 R & B (Ring
& 350 Ball Softening Point (.degree. F.) .sup.1Crude bitumen
from Whole Cold Lake Source .sup.2De-asphalted oil
[0064] As is illustrated by Table 3, the process of the present
invention significantly improves the oil quality from 10.9.degree.
API to 15.1.degree. API (for typical Cold Lake bitumen.). Moreover,
the oil's viscosity is significantly improved, thereby permitting
easier pumpability of the oil through standard pipelines.
Contaminants such as nitrogen, sulfur, nickel, vanadium and
Conradson carbon are reduced in the oil, which improves the value
of the de-asphalted oil. De-asphalting the, dehydrated and desalted
bitumen significantly reduces the use of diluents and thus the
overall cost of processing is reduced. With this low cost carbon
rejection method, the economics of bitumen production are greatly
improved since both the use of expensive natural gas and expensive
diluant are reduced dramatically.
* * * * *