Note: Descriptions are shown in the official language in which they were submitted.
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INTEGRATED XTL AND OPEN PIT OIL SANDS MINING PROCESSES
FIELD OF THE INVENTION
[0001] The invention relates to integration of processes for producing
hydrocarbon products. More particularly, the invention relates to integration
of
an XTL process for producing hydrocarbons with an open pit oil sands mining
process, and/or a bitumen treatment/upgrading process. The integration
includes one or more of steam integration, process water integration, water
treatment system integration, nitrogen integration, and integrated use of
carbon-
containing products or by-products from one process in another process.
BACKGROUND
[0002] The large deposits of oil sands found in parts of western Canada
are
important sources of heavy crude oil and/or bitumen. There are two primary
methods for recovering oil from oil sands: (a) by open pit surface mining, and
(b) in-situ extraction whereby steam and/or solvents are injected into
underground reservoirs to reduce the viscosity of the bitumen and allow it to
be
pumped to the surface for processing. An example of an in-situ extraction
method is SAGD (steam-assisted gravity drainage), in which steam is injected
into the reservoir to reduce the viscosity of the bitumen. In-situ extraction
methods are discussed in greater detail in commonly assigned Canadian Patent
Application No. 2,806,044.
[0003] In open pit surface mining of oil sands, the ore is mined and is
subsequently crushed for size reduction. Large amounts of hot water are then
added to the ore to form a slurry, and the slurry is transported to a vessel
where
the bitumen is at least partially separated from tailings by a flotation or
"froth
treatment" process whereby bitumen froth is recovered from the flotation
process.
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[0004] Once the bitumen is recovered, it undergoes various processing
and/or upgrading steps in a plant. For example, a diluent may be added to the
bitumen to enable it to be transported by pipeline. The bitumen may also
undergo further processing on-site, for example to convert it to SCO
(synthetic
crude oil). After upgrading, one or more product streams from the upgraded oil
product are transported via pipeline to another location, such as a remotely
located oil refinery.
[0005] As will be appreciated, open pit mining of oil sands is performed
in
remote areas. Large amounts of energy are consumed in producing steam to
heat water for preparation of the slurry of oil sands. Large amounts of fresh
water are also required to generate steam and the water needed for slurry
formation. Also, the diluents, solvents and other inputs required for
viscosity
reduction, dilution and/or upgrading the recovered product are typically
transported across great distances to the extraction site. In addition, the
transport of certain carbonaceous by-products of the bitumen upgrading
processes to off-site locations may not be practical or economically feasible.
Therefore, these by-products, which include asphaltene and coke, are either
stockpiled or disposed of.
[0006] The acronym XTL ("X"-to-liquid) is used to describe a group of
processes by which various carbon-containing materials are converted to
hydrocarbon products such as LPG, naphtha and diesel. XTL processes may
produce significant quantities of pressurized steam and water as by-products.
[0007] The carbonaceous feed material of the XTL process can include
coal,
coke (also referred to as "pet coke"), biomass, natural gas or any combination
of
these. Where natural gas is used as the feed material, the process may be
referred to as GTL (gas-to-liquid). The XTL process includes a first step in
which
the feed material is converted to a syngas comprising carbon monoxide and
hydrogen, a second step whereby the syngas is converted to the liquid
hydrocarbon product(s) by a F-T (Fischer-Tropsch) process, and a third step
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whereby the FT liquid product is converted to saleable hydrocarbon products
like
= diesel. It will be appreciated that this description of XTL is
oversimplified and
that the syngas generation and the F-T process steps may themselves include
multiple steps. Some of these additional steps are described in the detailed
description which follows below.
[0008] The inventors are not aware of any successful integration
of XTL
processes with open pit mining of oil sands and/or bitumen treatment/upgrading
processes, despite the fact that sources of XTL feed materials such as natural
gas
reservoirs are often located in close proximity to oil sands deposits, and
despite
the fact that products or by-products of one process can be utilized in a
different
process.
SUMMARY
[0009] In an embodiment, there is provided an integrated process
for
producing at least two hydrocarbon product streams. The integrated process
comprises: (a) converting a carbon-containing feed stream to a first
hydrocarbon product stream by an XTL process, wherein waste water is produced
by said XTL process; (b) diverting at least a portion of the waste water
produced
by said XTL process to an open pit oil sands mining process; (c) mixing the
waste water with oil sands ore produced by said open pit oil sands mining
process to form a slurry; (c) recovering said oil product from the slurry; and
(d)
converting said oil product to a second hydrocarbon product stream.
[0010] In an embodiment, the XTL process may comprise the steps
of: (i)
generating a syngas comprising carbon monoxide and hydrogen from a carbon-
containing feed stream, wherein the step of generating a syngas produces a
first
portion of the waste water; (ii) converting at least a portion of said syngas
to a
first hydrocarbon product stream by a Fischer-Tropsch (F-T) process, wherein
said F-T process produces a second portion of the waste water.
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[0011] In an embodiment, the waste water may be heated before it is
mixed with the oil sands ore. Where steam is produced by the XTL process, at
least a portion of the steam produced by the XTL process may be used to heat
the waste water before it is mixed with the oil sands ore. Furthermore, a
portion
of the steam produced by the XTL process may be used to generate power for
both the open pit oil sands mining process and the XTL process.
[0012] In an embodiment, a froth containing the oil product is extracted
from the slurry, and the oil product is recovered from the froth by a high
temperature froth treatment process. At least a portion of the steam produced
by the XTL process may be used in the high temperature froth treatment
process.
[0013] In an embodiment, the first hydrocarbon product stream produced
by the XTL process includes a solvent which is used in the high temperature
froth
treatment process.
[0014] In an embodiment, the first hydrocarbon product stream comprises
one or more liquid or gaseous hydrocarbon products. For example, the liquid or
gaseous hydrocarbon products may be selected from one or more members of
the group comprising liquefied petroleum gas (LPG), diesel, naphtha, and
mixtures of any two or more thereof.
[0015] In an embodiment, a portion of the first hydrocarbon product
stream is diverted to the open pit oil sands mining process. The diverted
portion
of the first hydrocarbon product stream may be mixed with the waste water and
the oil sands ore to form a slurry where, for example, the oil product is
extracted
from the oil sands ore by a solvent-water process. The diverted portion of the
first hydrocarbon product stream may comprise a light hydrocarbon fraction
comprised predominantly of C5 hydrocarbons.
[0016] In an embodiment, the oil product is bitumen or heavy crude oil.
Where the oil product comprises bitumen, the integrated process may further
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comprise diluting the bitumen with a sufficient amount of a diluent such that
the
diluted bitumen is transportable by a pipeline. The diluent may comprise
naphtha produced by the XTL process. Also, the step of converting the oil
product to a second hydrocarbon product may comprise a bitumen upgrading
process, with a carbon-containing by-product of said bitumen upgrading process
comprising coke.
[0017] In an embodiment, the integrated process further comprises
separation of air into an oxygen stream and a nitrogen stream, wherein the
oxygen stream is reacted with said carbon-containing feed stream in the
conversion of the carbon-containing feed stream to said syngas. The nitrogen
stream may be used for providing an inert atmosphere in process equipment
used in the XTL process, the open pit oil sands mining process, and/or the
conversion of the oil product to the second hydrocarbon product stream.
[0018] In an embodiment, the XTL process and the open pit oil sands
mining process are co-located in close proximity to one another.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described, by way of example only, with reference to
the attached drawings, in which:
[0019] Figure 1 illustrates an integrated process and system for
production
of first and second hydrocarbon product streams according to a first
embodiment
of the invention;
[0020] Figure 2 illustrates an integrated process and system for
production
of first and second hydrocarbon product streams according to a second
embodiment of the invention; and
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[0021] Figure 3 illustrates an integrated process and system for
production
of first and second hydrocarbon product streams according to a third
embodiment of the invention.
DETAILED DESCRIPTION
[0022] The following is a detailed description of various embodiments of
the invention, each of which integrates an XTL process and an open pit oil
sands
mining process for recovery of bitumen or heavy crude oil. Where the oil
product
is bitumen, there may also be integration of the XTL process with one or more
bitumen treatment/upgrading steps. In each embodiment, the integration
includes one or more of steam integration, process water integration, water
treatment system integration, nitrogen integration, and integrated use of
carbon-
containing products or by-products from one process in another. In the
embodiments described herein, the plants for performing the XTL process and,
where applicable, the bitumen upgrading process, are co-located with or in
close
proximity to the oil sands deposit from which the bitumen is recovered by open
pit mining.
[0023] Unless indicated otherwise below, conduits and components shown
in dashed lines (except for the boxes labelled "XTL", "Open Pit Mining Oil
Sands",
"Bitumen Processing", "Froth Processing" and "Bitumen Upgrading") are to be
understood as being optional.
[0024] Figure 1 illustrates an integrated process and system 100 for
production of first (XTL) and second (open pit oil sands mining) hydrocarbon
product streams according to a first embodiment of the invention. In system
100, the first hydrocarbon product stream comprises one or more XTL products
which are produced from a carbon-containing feed stream in the XTL process. In
this embodiment, the carbon-containing feed stream comprises natural gas
obtained from a natural gas source 12 such as a natural gas reservoir. The
natural gas is transported from source 12 through conduit 14 to a syngas
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generation unit 16 where it is converted to a synthesis gas (hereinafter
referred
to as "syngas").
[0025] The term "syngas" as used herein refers to a gas mixture
containing
varying amounts of carbon monoxide and hydrogen. A syngas may be produced
by steam reforming, partial oxidation, and/or autothermal reforming,
separately
or in combination, of natural gas; by gasification/co-gasification of a solid
or
liquid carbonaceous material; or any combinations of these gaseous, liquid and
solid materials. The reforming/gasification reaction consumes water (as steam)
and/or oxygen.
[0026] The syngas generation unit 16 in the first embodiment may
comprise a reforming unit wherein natural gas (predominantly methane) is
converted to syngas by one or more steps, with inputs of steam and molecular
oxygen. As shown in Figure 1, the oxygen input is provided by an air
separation
unit (ASU) 18 which separates oxygen from air, and steam is provided by a
steam and condensate system 19, which is further described below. Hydrogen
for natural gas desulfurization is provided by a hydrogen separation unit 20
which may separate a portion of the hydrogen from the syngas. Figure 1 shows
an oxygen conduit 62 extending from ASU 18 to syngas generation unit 16, a
steam conduit 64 between the steam and condensate system 19 and syngas
generation unit 16, and a hydrogen conduit 66 between the hydrogen separation
unit 20 and syngas generation unit 16.
[0027] The overall syngas generation reaction is exothermic and is cooled
by water, more specifically by boiling feed water (BFW) fed to the syngas
generation unit 16 through BFW conduit 68. The BFW is heated by the syngas to
generate steam which may be at high pressure, typically about 70-120 bar, and
high temperature. Steam and liquid waste water are removed from the syngas
generation unit 16 through one or more conduits, shown in Figure 1 as syngas
unit process water conduit 22 and syngas unit steam conduit 24.
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[0028] The syngas is transported from syngas generation unit 16 to
an F-T
= (Fischer-Tropsch) unit 26 through syngas conduit 28. In the F-T unit 26
the
syngas undergoes an F-T reaction whereby the syngas is catalytically converted
to a hydrocarbon product stream, typically a mixture of liquid and/or gaseous
hydrocarbons. Steam and liquid water are by-products of the F-T process, and
are removed from the F-T unit 26 through one or more conduits, shown in Figure
1 as F-T unit process water conduit 32 and F-T unit steam conduit 34. It can
be
seen that a portion of the process water from syngas generation unit 16 and F-
T
unit 26 is fed to water treatment unit 46 through process water conduit 70 in
which the water is treated to produce BFW, wherein the process water conduit
70
receives the process water through the water conduits 22 and 32 mentioned
above.
[0029] System 100 also includes an acid removal unit 108 which
removes
carbon dioxide and sulfur from the syngas produced by unit 16. The carbon
dioxide produced by unit 108 may be exhausted, however, it is possible to
achieve further integration by using this carbon dioxide in the open pit oil
sands
mining process, as discussed further below.
[0030] The composition of the hydrocarbon product stream produced
by F-
T unit 26 is variable, and depends at least partly on the F-T reaction
temperature, the reaction pressure, the type of catalyst (typically cobalt- or
iron-
based), and the composition of the syngas. The specific F-T process shown in
Figure 1 favours synthesis of long-chain hydrocarbons, and the XTL process
includes the step of converting the long-chain hydrocarbons to shorter-chain
hydrocarbon products in an F-T product upgrading unit 30, which receives the F-
T product through conduit 72. The shorter-chain hydrocarbons may be
separated into different fractions to provide two or more hydrocarbon products
such as liquefied petroleum gas (LPG), diesel and naphtha. For example, proper
hydrocracking of the FT product can yield winter diesel fuel with the required
specification for arctic conditions. The hydrocarbon products produced by the
F-
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T upgrading unit 30 are collectively referred to herein as the "first
hydrocarbon
product stream".
[0031] As shown in Figure 1, the ASU 18, syngas generation unit 16,
hydrogen separation unit 20, F-T unit 26 and F-T product upgrading unit 30 are
all included within the box labelled "XTL", indicating that the reactions
conducted
in these reaction units are part of the overall XTL process.
[0032] Turning now to the open pit oil sands mining process, Figure 1
illustrates the process steps and the system components involved in extracting
a
highly viscous oil product, such as heavy crude oil or bitumen, from an oil
sands
deposit by open pit mining. The steps and apparatus for recovering the bitumen-
containing ore from the pit and reducing it in size, for example by crushing,
are
schematically indicated in Figure 1 by box 130 labelled "Mining".
[0033] After the ore is recovered and crushed during the open pit mining
process 130, it is mixed with a large volume of hot water at a temperature of
about 50-80 C to form a pumpable slurry, the temperature of the slurry being
about 40-60 C, the slurry formation step and apparatus being schematically
illustrated in Figure 1 by box 132. In the system 100 of Figure 1, at least a
portion of the process water used for slurry formation at 132 comprises waste
(process) water recovered from the syngas generation unit 16 and the F-T unit
26. Accordingly, Figure 1 illustrates that a portion of the process water in
conduit 70, which receives the waste water from units 16 and 26, is diverted
toward the slurry formation process and apparatus through conduit 134.
Therefore, the system 100 of Figure 1 provides process water integration
between the XTL process and the open pit oil sands mining process, reducing
the
amount of fresh water which is consumed by the open pit oil sands mining
process.
[0034] The process water for slurry formation is typically heated to a
temperature of about 50-80 C before it contacts the recovered ore, and
therefore Figure 1 shows that the process water diverted from process water
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conduit 70 is passed through a heat exchanger 136, in which the process water
is heated by steam, and the heated process water flows from heat exchanger
136 to the slurry formation apparatus 132 through a hot water conduit 142. In
the system 100 of Figure 1, at least a portion of the steam required for
heating
the process water for slurry formation is provided by the steam and condensate
system 19 which, as mentioned above, receives waste steam produced by the
syngas generation unit 16 and the F-T unit 26. As shown in Figure 1, steam
from steam and condensate system 19 may be provided to the heat exchanger
136 through a steam conduit 138, and condensate produced by cooling the
steam in heat exchanger 136 may be returned to the steam and condensate
system 19 through condensate conduit 140. Therefore, the system 100 of Figure
1 provides steam integration between the XTL process and the open pit oil
sands
mining process, reducing the amount of steam which must be generated for the
open pit oil sands mining process, reducing the amount of energy which must be
generated to heat water for the open pit oil sands mining process. This
results in
energy saving and a reduction in the amount of water which must be treated.
[0035] It can be seen that Figure 1 also includes an auxiliary boiler 31
which may be regarded as belonging to the XTL process, and which is primarily
used during start-up of the XTL process, for example to drive the ASU 18
turbine. The auxiliary boiler 31 generates pressurized steam from BFW received
from water treatment unit 46 through BFW conduit 78, using heat from the
combustion of natural gas obtained from the natural gas source 12, and
optionally from off gases recovered from the XTL process and/or bitumen
recovery. Figure 1 shows a conduit 80for feeding natural gas from source 12 to
the auxiliary boiler 31. The steam produced by auxiliary boiler 31 is fed to
the
steam and condensate system 19 through steam conduit 82.
[0036] As shown in Figure 1, the steam and condensate system 19 also
provides steam to, and receives condensate from, a power generation unit 33
through respective conduits 84 and 86, wherein the power generation unit 33
produces power for the XTL process and/or the open pit mining process.
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[0037] Once the slurry of ore is produced at 132, it undergoes a bitumen
extraction step whereby bitumen is at least partially separated from the other
components of the slurry. In the system 100 of Figure 1, the slurry is pumped
through conduit 144 to a bitumen extraction unit, and the bitumen extraction
step and apparatus are schematically illustrated in Figure 1 by box 146, and
the
bitumen extraction step is considered part of the overall open pit mining
process.
The bitumen is recovered from the slurry as bitumen froth, the froth typically
comprising about 60 wt.% bitumen, 30 wt.% water and 10 wt.% solids. The
tailings separated during the bitumen extraction step 146 primarily comprise
sand and water.
[0038] Following extraction of bitumen froth from the oil sands slurry,
the
tailings from the bitumen extraction unit 146 may be processed so as to
recover
process water therefrom. In the system of Figure 1, the tailings management
step and apparatus are schematically illustrated in Figure 1 by box 148. The
process water recovered from the tailings is fed back into the process water
system, for example through water conduit 150. For example, the recovered
process water may be fed through conduit 150 directly to the water treatment
unit 46 or to the process water conduit 70. Therefore, the system 100 of
Figure
1 provides process water integration between the XTL process and the open pit
oil sands mining process, reducing the amount of fresh water which is consumed
by the open pit oil sands mining process and the XTL process.
[0039] As shown in Figure 1, carbon dioxide may be separated from the
tail
gas of the F-T unit 26, for example as by the SelexolTM process, in a CO2
removal
unit 152. A portion of the tail gas treated by the CO2 removal unit 152 may be
combusted, for example in auxiliary boiler 31, to which it may be fed through
conduit 168. The combustion of the tail gas helps to generate steam for the
steam and condensate system 19. Another portion of the tail gas from CO2
removal unit 152 may be fed to the sygas generation unit 16, for example to
adjust the H2:CO ratio of the syngas leaving the syngas generation unit 16.
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[0040] The CO2 separated from the tail gas may be fed to the tailings
management unit 148 through CO2 conduit 154. In addition, the CO2 separated
from the syngas by acid removal unit 108 may also be fed to the tailings
management unit 148 through a CO2 conduit 162. Research has shown that
injection of CO2 into the tailings can help the tailings settle out faster. As
indicated by the use of dotted lines in Figure 1, the removal of CO2 from the
syngas and/or the FT tail gas and the transfer of the recovered CO2 to the
tailings management unit 148 are optional. Therefore, the system 100 of Figure
1 provides CO2 integration between the XTL process and the open pit oil sands
mining process, reducing the amount of CO2 which must be supplied from off-
site.
[0041] The bitumen froth produced by the bitumen extraction unit 146
contains bitumen, fine clays and water, and undergoes a high temperature froth
treatment process (HTFT) in order to purify and recover bitumen contained in
the
froth. HTFT typically involves cleaning froth generated in extraction by
adding a
paraffinic solvent consisting of light alkanes, without aromatics, with the
primary
component of the solvent being pentanes, with less than about 5% butanes and
hexanes by mass. A typical paraffinic solvent may comprise about 0.44%
hexane, 1.22% cyclopentane, 77.95% n-pentane, 19.82% isopentane, and
0.57%butane by mass. When an amount of the paraffinic solvent is combined
with bitumen froth, a clean, diluted bitumen product (dilbit) is produced, the
dilbit containing less than about 0.5% sediment and water by mass. The solvent
also precipitates a quantity of asphaltene which, when the solvent is
distilled off,
produces a quantity of dry bitumen.
[0042] The HTFT step and apparatus are schematically illustrated in
Figure
1 by box 156, and Figure 1 shows that the froth from bitumen extraction unit
146 is transferred through conduit 158 to HTFT unit 156. In the HTFT unit, the
bitumen froth is treated with solvents to purify the bitumen and remove water,
fine sand and clay. In the system 100 of Figure 1, the steam for the HTFT
process is supplied through a steam conduit 160 from the steam and condensate
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system 19, which receives waste steam from the syngas generation unit 16 and
the F-T unit 26. Furthermore, the HTFT process is supplied with a paraffinic
solvent of variable composition from the FT product upgrading unit 30 which
may
have a composition as described above, the paraffinic solvent being supplied
through conduit 112. At least a portion of the tailings of the HTFT process
may
be processed in the tailings management apparatus 148 and/or the asphaltene in
the tailings may be incorporated into the carbon-containing feed stream fed to
the syngas generation unit 16, either on its own or in combination with
natural
gas, as disclosed in Canadian Patent Application No. 2,806,044 mentioned
above.
[0043] Therefore, the system 100 of Figure 1 provides steam integration
and solvent integration between the XTL process and the froth treatment
process, reducing the amount of steam which must be generated, and reducing
or eliminating the supply of paraffinic solvents from outside sources.
[0044] To reduce the viscosity of the purified bitumen to a sufficient
level
that it can be transported by a pipeline, a diluent is added to the bitumen.
In the
process and system of Figure 1, the diluent is added to the bitumen through
conduit 92 and comprises paraffinic diluents such as naphtha produced by the
XTL process, in the FT product upgrading step. The diluted bitumen product is
referred to as "Di!bit" in Figure 1. The use of naphtha produced by the XTL
process co-located with the SAGD process saves considerable costs in
transporting naphtha to the SAGD process location.
[0045] As mentioned above, steam and water are by-products of both
steps of the XTL process, i.e. the syngas generation process and the F-T
process.
The condensed water (process water) by-products from the syngas generation
process and the F-T process enter the integrated water treatment system shown
in Figure 1 through conduits 22 and 32, leading to water treatment unit 46
through process water conduit 94, where it is treated in water treatment unit
46.
However, these two process water streams 22 and 32 are not of the same
quality. The water separated from the syngas stream is usually clean water
which can be sent directly to a demineralization unit (DM) to produce BFW.
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However, the process water from the F-T unit 26 is contaminated with organic
acids and alcohols and typically requires biological treatment.
[0046] As mentioned above, process water separated by bitumen
extraction unit 146 is sent to the water treatment unit 46 through water
conduit
96 for treatment. Therefore, it can be seen that the water treatment unit 46,
serves both the XTL process and the open pit oil sands mining process. The
integration of the water treatment saves costs due to the fact that one water
treatment unit 46 serves both processes.
[0047] In addition, the amount of water processed by the water treatment
unit 46 may be less than the amount which would be processed if the two
processes were operated separately. In this regard, the XTL process is a net
producer of water, and open pit oil sands mining consumes water. Thus,
integration of water treatment saves energy in that less water needs to be
treated, reduces or eliminates the need to import fresh water, and also saves
capital costs in that a single water treatment unit serves both the XTL and
open
pit oil sands mining processes.
[0048] With regard to the steam by-products of the syngas generation unit
16 and the F-T unit 26, the steam conduits 24 and 34 transfer the steam to the
open pit oil sands mining process, ASU unit 18, and power generation unit 33
through the steam and condensate system 19, in which steam is conditioned,
separated from condensate, and distributed to users. As shown in Figure 1, the
steam and condensate system 19 may also provide steam and receive
condensate from steam condensation at a number of steps in the process.
Although not shown in the drawings, the steam from steam and condensate unit
19 could be utilized in the water treatment unit 46 where evaporative water
treatment is used.
[0049] The steam produced by syngas cooling in the syngas generation unit
16 is a high pressure (HP) steam (about 70-120 bar) which, along with the F-T
steam from the F-T unit 26, is sent to the steam and condensate system 19.
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From the steam and condensate unit, the HP steam may be used to heat water
for the open pit oil sands mining process. However, all or part of the HP
steam
may be sent to the ASU 18 through steam conduit 98 to drive the extraction
turbine (not shown in Figure 1), and the resulting intermediate pressure (IP)
steam may be extracted from the steam extraction turbine and then, along with
the turbine condensate, is sent to steam and condensate system 19 through
conduit 102.
[0050] On the other hand, steam produced by the F-T unit 26 may not be
directly usable to heat water for the open pit oil sands mining process. In
this
regard, F-T steam generated by a low temperature F-T process has a pressure of
about 10-20 bar, and at least a portion of this steam may instead be used for
power generation or process heating. The power generated by the F-T steam
may be consumed in both the XTL and open pit oil sands mining processes.
However, where a high temperature F-T process is conducted in the F-T unit,
the
F-T steam could be used to heat water for the open pit oil sands mining
process.
[0051] Further integration of the processes is possible. For example, as
noted above, the air separation unit 18 separates oxygen from air. The air
separation unit produces a nitrogen fraction which can be used for providing
an
inert atmosphere in one or more process vessels in the integrated system 100,
for example to purge a system for routine maintenance procedures. This
reduces the amount of nitrogen which must be transported to the site from a
remote location.
[0052] Figure 2 illustrates an integrated process and system 200 for
production of first and second hydrocarbon product streams according to a
second embodiment of the invention. Integrated system 200 includes many of
the same elements as integrated system 100, and like reference numerals are
used to show like elements of systems 100 and 200.
[0053] It can be seen that system 200 shares many elements with system
100, and includes the production of a first hydrocarbon product stream by an
XTL
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process and a second hydrocarbon stream by an open pit oil sands mining
process. The primary difference between systems 100 and 200 is that system
200 includes a bitumen upgrading process conducted in bitumen upgrading unit
52. The presence of a bitumen upgrading process and unit in system 200 allows
for additional process integration.
[0054] The bitumen upgrading unit 52 receives bitumen, which may be
diluted with a paraffinic solvent from the XTL process, through conduit 104
from
the HTFT unit 156 of the open pit oil sands mining process. The bitumen
upgrading unit 52 converts the bitumen to products such as diesel, naphtha and
gasoil, either as separate product streams or as a blended product stream, the
blended product being shown in Figure 2 as "SCO (synthetic crude oil). The
individual or blended products may be transported to another location for
further
processing, typically by pipeline. Alternatively, the individual products
produced
by the bitumen upgrading unit may be blended with products produced by the
XTL process.
[0055] For example, the relatively low quality diesel produced by the
bitumen upgrading unit 52 may be blended with the higher quality diesel
produced by the XTL process. The XTL diesel has a high cetane number, almost
zero sulfur, low density, but poor cold flow properties. On the other hand,
the
bitumen upgrader diesel has a low cetane number, relatively high sulfur
content,
higher density, and better cold flow properties. The XTL and bitumen upgrader
diesel streams can be blended to produce a diesel which can meet on-road
specifications, even for arctic conditions.
[0056] Similarly, the XTL naphtha and bitumen upgrader naphtha streams
can be blended and sold to the bitumen dilution market. Alternatively, the
bitumen upgrader naphtha can be mixed with gasoline, and/or the highly
paraffinic XTL naphtha could be used as a solvent in the HTFT or for bitumen
dilution.
CA 02822455 2014-06-03
17
[0057] The gasoil stream from the bitumen upgrading unit 52 may be sold
to refineries or can be converted to gasoline by adding a fluid catalytic
cracker
(FCC) unit to the bitumen upgrading unit 52.
[0058] Rather than undergoing complete bitumen upgrading in unit 52, the
bitumen may be only partially upgraded to provide a partially upgraded bitumen
having an API (American Petroleum Institute) gravity less than 20 API,
normally
considered the minimum density for transport by pipeline. A pipelinable blend
may be produced by blending the partially upgraded bitumen with XTL naphtha.
[0059] Therefore, it can be seen that the present process is capable of
producing a variety of product streams, and also provides integration of the
product streams from the XTL and open pit oil sands mining processes.
[0060] The bitumen upgrading process increases the relatively low H:C
ratio of the bitumen by a process referred to as "coke rejection", or by
hydrogen
addition, and both of these alternatives are shown as options in Figure 2.
[0061] Where the bitumen upgrading process comprises coke rejection, the
coke by-product generated by bitumen upgrading is typically considered a waste
product and may be stockpiled or landfilled. However, in the integrated
process
and system 200 according to Figure 2, the coke is incorporated into the carbon-
containing feed stream which is fed to the syngas generation unit 16 of the
XTL
process through a conduit (not shown), either on its own or in combination
with
natural gas, similar to the manner disclosed in above-mentioned Canadian
Patent
Application No. 2,806,044. In this regard, the natural gas conduit 14 is shown
in
dotted lines in Figure 2 to show that natural gas is optionally not included
in the
carbon-containing feed stream containing coke. It will be appreciated that the
syngas generation unit 16 of this embodiment may include both a reforming unit
to convert natural gas to syngas and a gasification unit in order to convert
the
coke to syngas. The co-gasification of carbon- containing materials in one
unit
could also be considered.
CA 02822455 2014-06-03
18
[0062] The coke is fed to the syngas generation unit 16 as an aqueous
slurry. The slurry may be prepared by combining process water with the coke in
a wet mill (not shown), and feeding the slurry to the syngas generation unit
16
where it is gasified or co-gasified (where natural gas is present), and
converted
to syngas by reaction with steam and oxygen.
[0063] Rather than upgrading bitumen by coke rejection, system 200 also
includes the option of upgrading the bitumen by hydrogen addition in the
bitumen upgrading unit 52. Bitumen upgrading by hydrogen addition also
increases the H:C ratio of the bitumen and converts the bitumen to SCO.
System 200 produces additional process integration in that a portion of the
hydrogen separated from the syngas by the hydrogen separation unit 20 is
diverted through hydrogen conduit 56 and is used in the bitumen upgrading unit
52.
[0064] Figure 3 illustrates an integrated process and system 300 for
production of first and second hydrocarbon product streams according to a
third
embodiment of the invention. Integrated system 300 includes many of the same
elements as integrated systems 100 and 200, and like reference numerals are
used to show like elements of systems 100, 200 and 300.
[0065] System 300 also includes the production of a first hydrocarbon
product stream by an XTL process and a second hydrocarbon stream by an open
pit oil sands mining process. The primary difference between system 300 and
system 100 is that system 300 uses a "solvent-water" process to extract the
bitumen from the oil sands ore in the slurry formation step and apparatus 132.
According to the solvent-water process, the ore is combined with process water
and solvent which may or may not be mixed together prior to contacting the
ore.
According to this system 300, the process water and solvent do not need to be
heated before contacting the oil sands ore, and therefore system 300 does not
include a heat exchanger 136.
CA 02822455 2013-08-01
19
[0066] As in system 100, the process water for slurry formation in system
300 includes waste water produced by the syngas generation unit 16 and the F-T
unit, thereby providing process water integration and reducing the amount of
fresh water consumed by the system 300.
[0067] The solvent for slurry formation in system 300 is a paraffinic
solvent
produced by the F-T product upgrading unit 30, and may be predominantly
comprised of a light hydrocarbon fraction, such as a C5 hydrocarbon fraction.
This fraction may be fed to the slurry formation apparatus through a solvent
conduit 164. Therefore, the system 300 provides both process water integration
and solvent or product integration since the process water and a paraffinic
solvent produced by the XTL process are utilized to form the slurry of ore in
the
open pit oil sands mining process.
[0068] The system 300 includes a bitumen extraction step and apparatus
146 by which the bitumen is separated from the tailings, and the tailings may
be
processed in the tailings management apparatus 148 as discussed above. In the
system 300 the extracted bitumen is not in the form of a froth, and therefore
no
high temperature froth treatment apparatus is provided in system 300.
However, the system 300 may include a solvent recovery unit 166 in which at
least a portion of the paraffinic solvent is recovered from the bitumen. The
recovered solvent may be recycled for use in the slurry formation step, for
example by entering conduit 164.
[0069] Although a number of the processes described above utilize natural
gas as a feed material for the XTL process, it will be appreciated that the
carbon-
containing feed material can include other carbon sources, such as coal and/or
biomass, either in addition to or instead of natural gas.
[0070] Although the word "conduit" is used in the above description to
describe means for transferring gases, liquids and solids between various
system
components, the use of the word "conduit" does not limit the means by which
gases, liquids and solids are transferred between system components. In some
CA 02822455 2014-06-03
cases, the conduits may be process piping, but this is not necessarily the
case.
For example, solids are generally transferred by means other than process
piping.
[0071] Furthermore, because the drawings illustrate the systems and
processes of the invention in a schematic manner, the routing of conduits, the
connections between two or more conduits, and the connections between the
conduits and system components, is not necessarily as shown in the drawings.
[0072] The scope of the claims should not be limited by the specific
embodiments set forth in the description, but should be given the broadest
interpretation consistent with the description as a whole.
