U.S. patent application number 12/970105 was filed with the patent office on 2011-06-23 for integrated enhanced oil recovery process.
This patent application is currently assigned to GREATPOINT ENERGY, INC.. Invention is credited to Andrew Perlman.
Application Number | 20110146978 12/970105 |
Document ID | / |
Family ID | 44060927 |
Filed Date | 2011-06-23 |
United States Patent
Application |
20110146978 |
Kind Code |
A1 |
Perlman; Andrew |
June 23, 2011 |
INTEGRATED ENHANCED OIL RECOVERY PROCESS
Abstract
The present invention relates to an enhanced oil recovery
process that is integrated with a synthesis gas generation process,
such as gasification or reforming, and an air separation process
for generating (i) an oxygen stream for use, for example, in the
syngas process or a combustion process, and (ii) a nitrogen stream
for EOR use.
Inventors: |
Perlman; Andrew; (Chicago,
IL) |
Assignee: |
GREATPOINT ENERGY, INC.
Cambridge
MA
|
Family ID: |
44060927 |
Appl. No.: |
12/970105 |
Filed: |
December 16, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61287571 |
Dec 17, 2009 |
|
|
|
Current U.S.
Class: |
166/266 ;
166/90.1 |
Current CPC
Class: |
C01B 3/34 20130101; C01B
2203/84 20130101; C10J 2300/0986 20130101; F25J 3/04569 20130101;
F25J 2260/80 20130101; C01B 2203/0415 20130101; C01B 2203/0445
20130101; Y02P 30/00 20151101; C01B 2203/0233 20130101; C10L 3/101
20130101; C01B 2203/043 20130101; E21B 43/166 20130101; Y02E 20/18
20130101; C01B 3/48 20130101; C10J 2300/0916 20130101; C10J
2300/1662 20130101; E21B 43/164 20130101; C10J 2300/0959 20130101;
C01B 2203/0255 20130101; C01B 2203/0485 20130101; C01B 2203/147
20130101; Y02P 20/145 20151101; C10J 2300/093 20130101; Y02P 30/30
20151101; C01B 2203/0894 20130101; C10L 3/08 20130101; C01B
2203/0283 20130101; C10J 3/00 20130101; C10J 2300/0943 20130101;
C10K 1/005 20130101; F25J 3/04539 20130101; C01B 2203/0495
20130101; F25J 3/04545 20130101; C10J 2300/1653 20130101; C10J
2300/1678 20130101; F25J 3/04533 20130101; C01B 2203/0244 20130101;
C01B 2203/0475 20130101; C10J 2300/0976 20130101 |
Class at
Publication: |
166/266 ;
166/90.1 |
International
Class: |
E21B 43/34 20060101
E21B043/34; E21B 43/25 20060101 E21B043/25 |
Claims
1. An integrated process to (i) produce an acid gas-depleted
product gas stream, (ii) produce an oxygen-rich gas stream, (iii)
produce a hydrocarbon-containing fluid from an underground
hydrocarbon reservoir via a hydrocarbon production well, and (iv)
enhance production of the hydrocarbon-containing fluid from the
underground hydrocarbon reservoir, the process comprising the steps
of: (1) injecting a pressurized nitrogen stream into the
underground hydrocarbon reservoir to enhance production of the
hydrocarbon-containing fluid from the underground hydrocarbon
reservoir via the hydrocarbon production well; (2) recovering the
hydrocarbon-containing fluid produced from the hydrocarbon
production well; (3) separating the hydrocarbon-containing fluid
into (a) a liquid hydrocarbon product stream and (b) a gaseous
hydrocarbon product stream; (4) producing a synthesis gas stream
from a carbonaceous feedstock, the synthesis gas stream comprising
(a) carbon dioxide, and (b) at least one of hydrogen and methane;
(5) treating the synthesis gas stream in an acid gas removal unit
to produce the acid gas-depleted synthesis gas stream and a carbon
dioxide-rich stream; (6) optionally treating the gaseous
hydrocarbon product stream in the acid gas removal unit to produce
an acid-gas depleted gaseous hydrocarbon product stream; (7)
optionally combusting at least a portion of one or more of the acid
gas-depleted synthesis gas stream, the gaseous hydrocarbon product
stream and the acid-gas depleted gaseous hydrocarbon product
stream; (8) separating an air stream into the oxygen-rich stream
and a nitrogen-rich stream; and (9) pressurizing the nitrogen-rich
stream to generate the pressurized nitrogen stream, wherein at
least a portion of the oxygen-rich stream is used in one or both of
steps (4) and (7).
2. The process of claim 1, wherein at least a portion of one or
more of the acid gas-depleted synthesis gas stream, the gaseous
hydrocarbon product stream and the acid-gas depleted gaseous
hydrocarbon product stream is combusted, and at least a portion of
the oxygen-rich stream is used for the combustion.
3. The process of claim 1, wherein at least a portion of the
oxygen-rich stream is used to produce the synthesis gas stream.
4. The process of claim 1, wherein the synthesis gas stream is
produced by a catalytic steam methane reforming process utilizing a
methane-containing stream as the carbonaceous feedstock.
5. The process of claim 1, wherein the synthesis gas stream is
produced by a non-catalytic gaseous partial oxidation process
utilizing a methane-containing stream as the carbonaceous
feedstock.
6. The process of claim 1, wherein the synthesis gas stream is
produced by a catalytic autothermal reforming process utilizing a
methane-containing stream as the carbonaceous feedstock.
7. The process of claim 1, wherein the synthesis gas stream is
produced by a non-catalytic thermal gasification process utilizing
a non-gaseous carbonaceous material as the carbonaceous
feedstock.
8. The process of claim 1, wherein the synthesis gas stream
comprises hydrogen and one or both of carbon monoxide and carbon
dioxide.
9. The process of claim 1, wherein the synthesis gas stream is
produced by a catalytic hydromethanation process utilizing a
non-gaseous carbonaceous material as the carbonaceous
feedstock.
10. The process of claim 1, wherein the synthesis gas stream
comprises methane, hydrogen and carbon dioxide, and optionally
carbon monoxide.
11. The process of claim 1, wherein at least a portion of the
synthesis gas stream is subject to a sour shift to generate a
hydrogen-enriched stream.
12. The process of claim 1, wherein the acid-gas depleted product
gas stream comprises hydrogen, and at least a portion of the
hydrogen is separated to generate a hydrogen product stream and a
hydrogen-depleted gas stream.
13. The process of claim 1, wherein the gaseous hydrocarbon product
stream is treated in the acid gas removal unit.
14. The process of claim 13, wherein the acid gas-depleted product
gas stream comprises an acid gas-depleted gaseous hydrocarbon
product stream and an acid gas-depleted synthesis gas stream.
15. The process of claim 1, wherein the carbon dioxide-rich stream
generated from acid gas removal is pressurized to generate a
pressurized carbon dioxide stream, at least a portion of which is
injected into the underground hydrocarbon reservoir.
16. A process to enhance production of a hydrocarbon-containing
fluid from an underground hydrocarbon reservoir via a hydrocarbon
production well, by injecting a pressurized nitrogen stream into
the underground hydrocarbon reservoir, wherein the pressurized
nitrogen stream is generated by a process comprising the steps of:
(I) recovering the hydrocarbon-containing fluid produced from the
hydrocarbon production well; (II) separating the
hydrocarbon-containing fluid into (a) a liquid hydrocarbon product
stream and (b) a gaseous hydrocarbon product stream; (III)
producing a synthesis gas stream from a carbonaceous feedstock, the
synthesis gas stream comprising (a) carbon dioxide, and (b) at
least one of hydrogen and methane; (IV) treating the synthesis gas
stream in an acid gas removal unit to produce an acid gas-depleted
synthesis gas stream and a carbon dioxide-rich stream; (V)
optionally treating the gaseous hydrocarbon product stream in the
acid gas removal unit to produce an acid-gas depleted gaseous
hydrocarbon product stream; (VI) optionally combusting at least a
portion of one or more of the acid gas-depleted synthesis gas
stream, the gaseous hydrocarbon product stream and the acid-gas
depleted gaseous hydrocarbon product stream; (VII) separating an
air stream into an oxygen-rich stream and a nitrogen-rich stream;
and (VIII) pressurizing the nitrogen-rich stream to generate the
pressurized nitrogen stream, wherein at least a portion of the
oxygen-rich stream is used in one or both of steps (III) and
(VI).
17. An apparatus for producing a hydrocarbon-containing fluid, an
acid gas-depleted product gas stream and an oxygen-rich stream, the
apparatus comprising: (A) a synthesis gas production system adapted
to produce a synthesis gas from a carbonaceous feedstock, the
synthesis gas comprising (i) carbon dioxide and (ii) at least one
of hydrogen and methane; (B) an injection well in fluid
communication with an underground hydrocarbon reservoir comprising
a hydrocarbon-containing fluid, the injection well adapted to
inject a pressurized nitrogen stream into the underground
hydrocarbon reservoir for enhanced oil recovery; (C) a hydrocarbon
production well in fluid communication with the underground
hydrocarbon reservoir, the hydrocarbon production well adapted to
remove hydrocarbon-containing fluid from the underground
hydrocarbon reservoir; (D) a separation device in fluid
communication with the hydrocarbon production well, the separation
device adapted (i) to receive the hydrocarbon fluid from the
hydrocarbon production well, and (ii) to separate the hydrocarbon
fluid into a liquid hydrocarbon product stream and a gaseous
hydrocarbon product stream; (E) an acid gas removal unit in fluid
communication with the synthesis gas generation system, the acid
gas removal unit adapted to (i) receive the synthesis gas from the
synthesis gas generation system, and (ii) treat the synthesis gas
to remove acid gases and produce the acid gas-depleted product gas
stream and a carbon dioxide-rich stream; (F) an air separation unit
adapted to (i) receive an air stream and (ii) separate the air
stream into an oxygen-rich stream and a nitrogen-rich recycle
stream; and (G) a compressor unit in fluid communication with the
air separation unit and the injection well, the compressor unit
adapted to (i) receive the nitrogen-rich recycle stream, and (ii)
compress the nitrogen-rich recycle stream to generate the
pressurized nitrogen stream, and (iii) provide the pressurized
nitrogen stream to the injection well.
18. The apparatus of claim 17, wherein the injection well is
further adapted to inject a pressurized carbon dioxide stream into
the underground hydrocarbon reservoir, and the apparatus further
comprises a compressor unit in fluid communication with the acid
gas removal unit and the injection well, the compressor unit
adapted to (i) receive the carbon dioxide-rich stream, and (ii)
compress the carbon dioxide recycle stream to generate the
pressurized carbon dioxide stream, and (iii) provide the
pressurized carbon dioxide stream to the injection well.
19. The apparatus of claim 17, wherein the acid gas removal unit is
adapted to receive a combined stream of the synthesis gas and the
gaseous hydrocarbon product stream, and treat the combined stream
to remove acid gases and produce an acid gas-depleted product gas
stream and a carbon dioxide-rich stream.
20. The apparatus of claim 17, wherein the acid gas removal unit is
also adapted to receive the gaseous hydrocarbon product stream from
the separation device, and treat the gaseous hydrocarbon product
stream to remove acid gases and produce an acid gas-depleted
gaseous hydrocarbon product stream.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application claims priority under 35 U.S.C. .sctn.119
from U.S. Provisional Application Ser. No. 61/287,571 (filed 17
Dec. 2009), the disclosure of which is incorporated by reference
herein for all purposes as if fully set forth.
[0002] This application is related to commonly-owned U.S. patent
applications Ser. Nos. 12/906,552 (attorney docket no. FN-0055 US
NP1, entitled INTEGRATED ENHANCED OIL RECOVERY PROCESS) and
12/906,547 (attorney docket no. FN-0056 US NP1, entitled INTEGRATED
ENHANCED OIL RECOVERY PROCESS), both of which were filed 18 Oct.
2010; and ______ (attorney docket no. FN-0058 US NP1, entitled
INTEGRATED ENHANCED OIL RECOVERY PROCESS), filed concurrently
herewith.
FIELD OF THE INVENTION
[0003] The present invention relates to an enhanced oil recovery
process that is integrated with a synthesis gas generation process,
such as gasification or reforming, and an air separation process
for generating (i) an oxygen stream for use, for example, in the
syngas process or a combustion process, and (ii) a nitrogen stream
for EOR use.
BACKGROUND OF THE INVENTION
[0004] In view of dwindling supplies of crude oil, enhanced oil
recovery (EOR) techniques are receiving renewed attention.
[0005] Typically, oil is produced using the natural pressure of an
oil reservoir to drive the crude into the well bore from where it
is brought to the surface with conventional pumps. After some
period of production, the natural pressure of the oil reservoir
decreases and production dwindles. In the 1940s, producers
incorporated secondary recovery by utilizing injected water, steam
and/or natural gas to drive the crude to the well bore prior to
pumping it to the surface.
[0006] Once the easily extracted oil already has been recovered,
producers may turn to tertiary or enhanced oil recovery (EOR)
techniques. One known such EOR technique is high-pressure nitrogen
injection, which helps to repressurize the oil reservoir.
[0007] EOR based on high pressure nitrogen injection can also
involve other techniques such as CO.sub.2 injection/flood, which
may be done concurrently and/or consecutively with the nitrogen
injection.
[0008] CO.sub.2 injection also helps to repressurize the oil
reservoir. The high-pressure CO.sub.2 also acts as a solvent,
dissolving the residual oil, thereby reducing its viscosity and
improving its flow characteristics, allowing it to be pumped out of
an aging reservoir.
[0009] One difficulty with the use of nitrogen and optionally
CO.sub.2 to increase oil production is that it requires large
quantities of both gases, and the availability of such large
quantities is limited.
[0010] Nitrogen is generally available from air separation
processes, but it is not considered economical to utilize air
separation processes solely for the generation of nitrogen for
EOR.
[0011] CO.sub.2 from natural sources can be utilized, but generally
requires the natural source to be in the proximity of the oil
reservoir to avoid the construction and use of pipelines, which
could make such use uneconomical.
[0012] Use of CO.sub.2 from combustion sources (such as power
plants) has also been considered (see, for example, U.S. Pat. No.
7,299,868 and publications cited therein), but the separation of
CO.sub.2 from the combustion gases is difficult and generally not
considered economical.
[0013] More recently, CO.sub.2 from synthesis gas production
operations has been considered for use in EOR. See, for example,
U.S. Pat. No. 7,481,275. Synthesis gas production operations
include, for example, catalytic gasification and hydromethanation
processes, non-catalytic gasification processes and methane
reforming processes. These processes typically produce one or more
of methane, hydrogen and/or syngas (a mixture of hydrogen and
carbon monoxide) as a raw gas product, which can be processed and
ultimately used for power generation and/or other industrial
applications. These processes also produce CO.sub.2, which is
removed via acid gas removal processes, as is generally known to
those of ordinary skill in the relevant art. Historically, this
CO.sub.2 has simply been vented to the atmosphere but, in view of
environmental concerns, capture and sequestration/use of this
CO.sub.2 is becoming a necessity. EOR is thus a logical outlet for
CO.sub.2 streams from synthesis gas production operations.
[0014] At least one such synthesis gas production operation which
utilizes a CO.sub.2 by-product stream for EOR currently exists at
the Great Plains Synfuels Plant (near Beulah, N. Dak. USA). At this
facility, coal/lignite is gasified to a synthesis gas stream
containing carbon dioxide, which is separated via a solvent-based
acid gas removal technique. The resulting CO.sub.2 stream (which is
greater than 95% pure) is compressed and transported via a 205-mile
supercritical CO.sub.2 pipeline to oil fields in Canada for use in
EOR operations. This operation is described in more detail in Perry
and Eliason, "CO.sub.2 Recovery and Sequestration at Dakota
Gasification Company" (October 2004) (available from
www.gasification.org), and on the Dakota Gasification Company
website (www.dakotagas.com).
[0015] A disadvantage in this operation is the pipeline, as
supercritical CO.sub.2 is considered a hazardous material. The
construction, permitting, operation and maintenance of a
supercritical CO.sub.2 pipeline, particularly one as long as 205
miles, is expensive. A more advantageous way to get the CO.sub.2
from the synthesis gas operation to the EOR site would, therefore,
be highly desirable.
[0016] Another disadvantage to the use of CO.sub.2 for EOR is that,
as more CO.sub.2 is pumped into an oil reservoir, more CO.sub.2 is
also produced along with the other liquids and gases that come out
of the well. Traditionally, CO.sub.2 that is co-produced with oil
is separated and vented to the atmosphere; however, as with
synthesis gas production operations, environmental concerns make
this CO.sub.2 venting undesirable.
[0017] It would, therefore, be highly desirable to integrate EOR
processes with both synthesis gas production processes and air
separation processes in a way that minimizes the release of
CO.sub.2 into the atmosphere (maximizes capture and sequestration
of CO.sub.2), reduces the need for long nitrogen (and CO.sub.2 when
utilized) transport pipelines, and improves the overall
integration, efficiency and economics of the individual processes.
The present invention provides such an integration.
SUMMARY OF THE INVENTION
[0018] In a first aspect, the present invention provides an
integrated process to (i) produce an acid gas-depleted product gas
stream, (ii) produce an oxygen-rich gas stream, (iii) produce a
hydrocarbon-containing fluid from an underground hydrocarbon
reservoir via a hydrocarbon production well, and (iv) enhance
production of the hydrocarbon-containing fluid from the underground
hydrocarbon reservoir, the process comprising the steps of:
[0019] (1) injecting a pressurized nitrogen stream into the
underground hydrocarbon reservoir to enhance production of the
hydrocarbon-containing fluid from the underground hydrocarbon
reservoir via the hydrocarbon production well;
[0020] (2) recovering the hydrocarbon-containing fluid produced
from the hydrocarbon production well;
[0021] (3) separating the hydrocarbon-containing fluid into (a) a
liquid hydrocarbon product stream and (b) a gaseous hydrocarbon
product stream;
[0022] (4) producing a synthesis gas stream from a carbonaceous
feedstock, the synthesis gas stream comprising (a) carbon dioxide,
and (b) at least one of hydrogen and methane;
[0023] (5) treating the synthesis gas stream in an acid gas removal
unit to produce the acid gas-depleted product gas stream and a
carbon dioxide-rich stream;
[0024] (6) optionally treating the gaseous hydrocarbon product
stream in the acid gas removal unit to produce an acid-gas depleted
gaseous hydrocarbon product stream;
[0025] (7) optionally combusting at least a portion of one or more
of the acid gas-depleted synthesis gas stream, the gaseous
hydrocarbon product stream and the acid-gas depleted gaseous
hydrocarbon product stream;
[0026] (8) separating an air stream into the oxygen-rich stream and
a nitrogen-rich stream; and
[0027] (9) pressurizing the nitrogen-rich stream to generate the
pressurized nitrogen stream,
[0028] wherein at least a portion of the oxygen-rich stream is used
in one or both of steps (4) and (7).
[0029] In a second aspect, the present invention provides a process
to enhance production of a hydrocarbon-containing fluid from an
underground hydrocarbon reservoir via a hydrocarbon production
well, by injecting a pressurized nitrogen stream into the
underground hydrocarbon reservoir, wherein the pressurized nitrogen
stream is generated by a process comprising the steps of:
[0030] (I) recovering the hydrocarbon-containing fluid produced
from the hydrocarbon production well;
[0031] (II) separating the hydrocarbon-containing fluid into (a) a
liquid hydrocarbon product stream and (b) a gaseous hydrocarbon
product stream;
[0032] (III) producing a synthesis gas stream from a carbonaceous
feedstock, the synthesis gas stream comprising (a) carbon dioxide,
and (b) at least one of hydrogen and methane;
[0033] (IV) treating the synthesis gas stream in an acid gas
removal unit to produce an acid gas-depleted synthesis gas stream
and a carbon dioxide-rich stream;
[0034] (V) optionally treating the gaseous hydrocarbon product
stream in the acid gas removal unit to produce an acid-gas depleted
gaseous hydrocarbon product stream;
[0035] (VI) optionally combusting at least a portion of one or more
of the acid gas-depleted synthesis gas stream, the gaseous
hydrocarbon product stream and the acid-gas depleted gaseous
hydrocarbon product stream;
[0036] (VII) separating an air stream into an oxygen-rich stream
and a nitrogen-rich stream; and
[0037] (VIII) pressurizing the nitrogen-rich stream to generate the
pressurized nitrogen stream,
[0038] wherein at least a portion of the oxygen-rich stream is used
in one or both of steps (III) and (VI).
[0039] In a specific embodiment of the first and second aspects,
the carbon dioxide-rich stream generated from acid gas removal is
pressurized to generate a pressurized carbon dioxide stream, at
least a portion of which is injected into the underground
hydrocarbon reservoir.
[0040] In another specific embodiment of the first and second
aspects, steps (7) and (VI) are present, and the combustion is used
to produce energy (for example, mechanical and/or electrical
energy) that is used at least in part for the air separation step
(steps (8) and (VII)) and/or pressurization (compression) steps
(steps (9) and (VIII), and/or CO.sub.2 compression).
[0041] In a third aspect, the invention provides an apparatus for
producing a hydrocarbon-containing fluid, an acid gas-depleted
product gas stream and an oxygen-rich stream, the apparatus
comprising:
[0042] (A) a synthesis gas production system adapted to produce a
synthesis gas from a carbonaceous feedstock, the synthesis gas
comprising (i) carbon dioxide and (ii) at least one of hydrogen and
methane;
[0043] (B) an injection well in fluid communication with an
underground hydrocarbon reservoir comprising a
hydrocarbon-containing fluid, the injection well adapted to inject
a pressurized nitrogen stream into the underground hydrocarbon
reservoir for enhanced oil recovery;
[0044] (C) a hydrocarbon production well in fluid communication
with the underground hydrocarbon reservoir, the hydrocarbon
production well adapted to remove hydrocarbon-containing fluid from
the underground hydrocarbon reservoir;
[0045] (D) a separation device in fluid communication with the
hydrocarbon production well, the separation device adapted (i) to
receive the hydrocarbon fluid from the hydrocarbon production well,
and (ii) to separate the hydrocarbon fluid into a liquid
hydrocarbon product stream and a gaseous hydrocarbon product
stream;
[0046] (E) an acid gas removal unit in fluid communication with the
synthesis gas generation system, the acid gas removal unit adapted
to (i) receive the synthesis gas from the synthesis gas generation
system, and (ii) treat the synthesis gas to remove acid gases and
produce the acid gas-depleted product gas stream and a carbon
dioxide-rich stream;
[0047] (F) an air separation unit adapted to (i) receive an air
stream and (ii) separate the air stream into an oxygen-rich stream
and a nitrogen-rich recycle stream; and
[0048] (G) a compressor unit in fluid communication with the air
separation unit and the injection well, the compressor unit adapted
to (i) receive the nitrogen-rich recycle stream, and (ii) compress
the nitrogen-rich recycle stream to generate the pressurized
nitrogen stream, and (iii) provide the pressurized nitrogen stream
to the injection well.
[0049] In a specific embodiment of the third aspect, the injection
well is further adapted to inject a pressurized carbon dioxide
stream into the underground hydrocarbon reservoir, and the
apparatus further comprises a compressor unit in fluid
communication with the acid gas removal unit and the injection
well, the compressor unit adapted to (i) receive the carbon
dioxide-rich stream, and (ii) compress the carbon dioxide recycle
stream to generate the pressurized carbon dioxide stream, and (iii)
provide the pressurized carbon dioxide stream to the injection
well.
[0050] In another specific embodiment of the third aspect, the acid
gas removal unit is adapted to receive a combined stream of the
synthesis gas and the gaseous hydrocarbon product stream, and treat
the combined stream to remove acid gases and produce an acid
gas-depleted product gas stream and a carbon dioxide-rich
stream.
[0051] In another specific embodiment of the third aspect, the acid
gas removal unit is also adapted to receive the gaseous hydrocarbon
product stream from the separation device, and treat the gaseous
hydrocarbon product stream to remove acid gases and produce an acid
gas-depleted gaseous hydrocarbon product stream. In such a case,
the acid gas-depleted product gas stream will comprise both the
acid gas-depleted gaseous hydrocarbon product stream and an acid
gas-depleted synthesis gas stream (separate or combined).
[0052] These and other embodiments, features and advantages of the
present invention will be more readily understood by those of
ordinary skill in the art from a reading of the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0053] FIG. 1 is a diagram of an embodiment of an integrated
process in accordance with the present invention.
[0054] FIG. 2 is a diagram of a first specific embodiment of the
integrated process in accordance with the present invention.
[0055] FIG. 3 is a diagram of an embodiment of the gas processing
portion of the integrated process of FIG. 2.
[0056] FIG. 4 is a diagram of a second specific embodiment of the
integrated process in accordance with the present invention.
[0057] FIG. 5 is a diagram of an embodiment of the gas processing
portion of the integrated process of FIG. 4.
[0058] FIG. 6 is a diagram of an electrical power block suitable
for use in conjunction with the present invention.
DETAILED DESCRIPTION
[0059] The present disclosure relates to integrating synthesis gas
production processes and air separation processes with enhanced oil
recovery processes. Further details are provided below.
[0060] In the context of the present description, all publications,
patent applications, patents and other references mentioned herein,
if not otherwise indicated, are explicitly incorporated by
reference herein in their entirety for all purposes as if fully set
forth.
[0061] Unless otherwise defined, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which this disclosure belongs. In case
of conflict, the present specification, including definitions, will
control.
[0062] Except where expressly noted, trademarks are shown in upper
case.
[0063] Although methods and materials similar or equivalent to
those described herein can be used in the practice or testing of
the present disclosure, suitable methods and materials are
described herein.
[0064] Unless stated otherwise, all percentages, parts, ratios,
etc., are by weight.
[0065] Unless stated otherwise, pressures expressed in psi units
are gauge, and pressures expressed in kPa units are absolute.
[0066] When an amount, concentration, or other value or parameter
is given as a range, or a list of upper and lower values, this is
to be understood as specifically disclosing all ranges formed from
any pair of any upper and lower range limits, regardless of whether
ranges are separately disclosed. Where a range of numerical values
is recited herein, unless otherwise stated, the range is intended
to include the endpoints thereof, and all integers and fractions
within the range. It is not intended that the scope of the present
disclosure be limited to the specific values recited when defining
a range.
[0067] When the term "about" is used in describing a value or an
end-point of a range, the disclosure should be understood to
include the specific value or end-point referred to.
[0068] As used herein, the terms "comprises," "comprising,"
"includes," "including," "has," "having" or any other variation
thereof, are intended to cover a non-exclusive inclusion. For
example, a process, method, article, or apparatus that comprises a
list of elements is not necessarily limited to only those elements
but can include other elements not expressly listed or inherent to
such process, method, article, or apparatus. Further, unless
expressly stated to the contrary, "or" refers to an inclusive or
and not to an exclusive or. For example, a condition A or B is
satisfied by any one of the following: A is true (or present) and B
is false (or not present), A is false (or not present) and B is
true (or present), and both A and B are true (or present).
[0069] The use of "a" or "an" to describe the various elements and
components herein is merely for convenience and to give a general
sense of the disclosure. This description should be read to include
one or at least one and the singular also includes the plural
unless it is obvious that it is meant otherwise.
[0070] The term "substantial portion", as used herein, unless
otherwise defined herein, means that greater than about 90% of the
referenced material, preferably greater than about 95% of the
referenced material, and more preferably greater than about 97% of
the referenced material. The percent is on a molar basis when
reference is made to a molecule (such as methane, carbon dioxide,
carbon monoxide and hydrogen sulfide), and otherwise is on a weight
basis (such as the liquid component of the hydrocarbon-containing
fluid).
[0071] The term "predominant portion", as used herein, unless
otherwise defined herein, means that greater than about 50% of the
referenced material. The percent is on a molar basis when reference
is made to a molecule (such as hydrogen, methane, carbon dioxide,
carbon monoxide and hydrogen sulfide), and otherwise is on a weight
basis (such as the liquid component of the hydrocarbon-containing
fluid).
[0072] The term "hydrocarbon-containing fluid", as used herein,
means a fluid comprising any hydrocarbon liquid and/or gas. A
hydrocarbon-containing fluid may also comprise solid particles.
Oil, gas-condensate and the like, and also their mixtures with
other liquids such as water, may be examples of a liquid contained
in a hydrocarbon-containing fluid. Any gaseous hydrocarbon (for
example, methane, ethane, propane, propylene, butane or the like),
and mixtures of gaseous hydrocarbons, may be contained in a
hydrocarbon-containing fluid. In the context of the present
invention, the hydrocarbon-containing fluid is recovered from an
underground hydrocarbon reservoir, such as an oil-bearing
formation, a gas-condensate reservoir, a natural gas reservoir and
the like.
[0073] The term "carbonaceous" as used herein is synonymous with
hydrocarbon.
[0074] The term "carbonaceous material" as used herein is a
material containing organic hydrocarbon content. Carbonaceous
materials can be classified as biomass or non-biomass materials as
defined herein.
[0075] The term "biomass" as used herein refers to carbonaceous
materials derived from recently (for example, within the past 100
years) living organisms, including plant-based biomass and
animal-based biomass. For clarification, biomass does not include
fossil-based carbonaceous materials, such as coal. For example, see
US2009/0217575A1 and US2009/0217587A1.
[0076] The term "plant-based biomass" as used herein means
materials derived from green plants, crops, algae, and trees, such
as, but not limited to, sweet sorghum, bagasse, sugarcane, bamboo,
hybrid poplar, hybrid willow, albizia trees, eucalyptus, alfalfa,
clover, oil palm, switchgrass, sudangrass, millet, jatropha, and
miscanthus (e.g., Miscanthus x giganteus). Biomass further include
wastes from agricultural cultivation, processing, and/or
degradation such as corn cobs and husks, corn stover, straw, nut
shells, vegetable oils, canola oil, rapeseed oil, biodiesels, tree
bark, wood chips, sawdust, and yard wastes.
[0077] The term "animal-based biomass" as used herein means wastes
generated from animal cultivation and/or utilization. For example,
biomass includes, but is not limited to, wastes from livestock
cultivation and processing such as animal manure, guano, poultry
litter, animal fats, and municipal solid wastes (e.g., sewage).
[0078] The term "non-biomass", as used herein, means those
carbonaceous materials which are not encompassed by the term
"biomass" as defined herein. For example, non-biomass include, but
is not limited to, anthracite, bituminous coal, sub-bituminous
coal, lignite, petroleum coke, asphaltenes, liquid petroleum
residues or mixtures thereof. For example, see US2009/0166588A1,
US2009/0165379A1, US2009/0165380A1, US2009/0165361A1,
US2009/0217590A1 and US2009/0217586A1.
[0079] The terms "petroleum coke" and "petcoke" as used here
include both (i) the solid thermal decomposition product of
high-boiling hydrocarbon fractions obtained in petroleum processing
(heavy residues--"resid petcoke"); and (ii) the solid thermal
decomposition product of processing tar sands (bituminous sands or
oil sands--"tar sands petcoke"). Such carbonization products
include, for example, green, calcined, needle and fluidized bed
petcoke.
[0080] Resid petcoke can also be derived from a crude oil, for
example, by coking processes used for upgrading heavy-gravity
residual crude oil, which petcoke contains ash as a minor
component, typically about 1.0 wt % or less, and more typically
about 0.5 wt % of less, based on the weight of the coke. Typically,
the ash in such lower-ash cokes comprises metals such as nickel and
vanadium.
[0081] Tar sands petcoke can be derived from an oil sand, for
example, by coking processes used for upgrading oil sand. Tar sands
petcoke contains ash as a minor component, typically in the range
of about 2 wt % to about 12 wt %, and more typically in the range
of about 4 wt % to about 12 wt %, based on the overall weight of
the tar sands petcoke. Typically, the ash in such higher-ash cokes
comprises materials such as silica and/or alumina.
[0082] Petroleum coke has an inherently low moisture content,
typically, in the range of from about 0.2 to about 2 wt % (based on
total petroleum coke weight); it also typically has a very low
water soaking capacity to allow for conventional catalyst
impregnation methods. The resulting particulate compositions
contain, for example, a lower average moisture content which
increases the efficiency of downstream drying operation versus
conventional drying operations.
[0083] The petroleum coke can comprise at least about 70 wt %
carbon, at least about 80 wt % carbon, or at least about 90 wt %
carbon, based on the total weight of the petroleum coke. Typically,
the petroleum coke comprises less than about 20 wt % inorganic
compounds, based on the weight of the petroleum coke.
[0084] The term "asphaltene" as used herein is an aromatic
carbonaceous solid at room temperature, and can be derived, for
example, from the processing of crude oil and crude oil tar
sands.
[0085] The term "coal" as used herein means peat, lignite,
sub-bituminous coal, bituminous coal, anthracite, or mixtures
thereof. In certain embodiments, the coal has a carbon content of
less than about 85%, or less than about 80%, or less than about
75%, or less than about 70%, or less than about 65%, or less than
about 60%, or less than about 55%, or less than about 50% by
weight, based on the total coal weight. In other embodiments, the
coal has a carbon content ranging up to about 85%, or up to about
80%, or up to about 75% by weight, based on the total coal weight.
Examples of useful coal include, but are not limited to, Illinois
#6, Pittsburgh #8, Beulah (N. Dak.), Utah Blind Canyon, and Powder
River Basin (PRB) coals. Anthracite, bituminous coal,
sub-bituminous coal, and lignite coal may contain about 10 wt %,
from about 5 to about 7 wt %, from about 4 to about 8 wt %, and
from about 9 to about 11 wt %, ash by total weight of the coal on a
dry basis, respectively. However, the ash content of any particular
coal source will depend on the rank and source of the coal, as is
familiar to those skilled in the art. See, for example, "Coal Data:
A Reference", Energy Information Administration, Office of Coal,
Nuclear, Electric and Alternate Fuels, U.S. Department of Energy,
DOE/EIA-0064(93), February 1995.
[0086] The ash produced from combustion of a coal typically
comprises both a fly ash and a bottom ash, as are familiar to those
skilled in the art. The fly ash from a bituminous coal can comprise
from about 20 to about 60 wt % silica and from about 5 to about 35
wt % alumina, based on the total weight of the fly ash. The fly ash
from a sub-bituminous coal can comprise from about 40 to about 60
wt % silica and from about 20 to about 30 wt % alumina, based on
the total weight of the fly ash. The fly ash from a lignite coal
can comprise from about 15 to about 45 wt % silica and from about
20 to about 25 wt % alumina, based on the total weight of the fly
ash. See, for example, Meyers, et al. "Fly Ash. A Highway
Construction Material," Federal Highway Administration, Report No.
FHWA-IP-76-16, Washington, DC, 1976.
[0087] The bottom ash from a bituminous coal can comprise from
about 40 to about 60 wt % silica and from about 20 to about 30 wt %
alumina, based on the total weight of the bottom ash. The bottom
ash from a sub-bituminous coal can comprise from about 40 to about
50 wt % silica and from about 15 to about 25 wt % alumina, based on
the total weight of the bottom ash. The bottom ash from a lignite
coal can comprise from about 30 to about 80 wt % silica and from
about 10 to about 20 wt % alumina, based on the total weight of the
bottom ash. See, for example, Moulton, Lyle K. "Bottom Ash and
Boiler Slag," Proceedings of the Third International Ash
Utilization Symposium, U.S. Bureau of Mines, Information Circular
No. 8640, Washington, DC, 1973.
[0088] A carbonaceous material such as methane can be biomass or
non-biomass under the above definitions depending on its source of
origin.
[0089] The term "unit" refers to a unit operation. When more than
one "unit" is described as being present, those units are operated
in a parallel fashion. A single "unit", however, may comprise more
than one of the units in series, or in parallel, depending on the
context. For example, an acid gas removal unit may comprise a
hydrogen sulfide removal unit followed in series by a carbon
dioxide removal unit. As another example, a contaminant removal
unit may comprise a first removal unit for a first contaminant
followed in series by a second removal unit for a second
contaminant. As yet another example, a compressor may comprise a
first compressor to compress a stream to a first pressure, followed
in series by a second compressor to further compress the stream to
a second (higher) pressure.
[0090] The materials, methods, and examples herein are illustrative
only and, except as specifically stated, are not intended to be
limiting.
General Process Information
[0091] In one embodiment of the invention, an acid gas-depleted
product gas steam (38), an oxygen-rich stream (14) and a
hydrocarbon-containing fluid (82) are produced in an integrated
EOR, air separation and synthesis gas production process as
illustrated in FIGS. 1-6.
[0092] In order to facilitate the integration, in one embodiment
the synthesis gas production system (facility) and air separation
units are both proximate to the EOR location (field), such as on
the same or an adjoining land parcel.
Enhanced Oil Recovery
[0093] Referring to FIG. 1, the EOR portion of the process involves
injecting a pressurized nitrogen stream (19), and optionally a
pressurized carbon dioxide stream (89), via an injection well (500)
(one or more) into an underground hydrocarbon reservoir (20)
utilizing techniques well known to those of ordinary skill in the
relevant art.
[0094] As indicated above, the pressurized nitrogen stream (19)
assists in the repressurization of the underground reservoir.
Typically, the pressurized nitrogen stream (19) will be injected
into the underground reservoir at a pressure of at least about 1200
psig (about 8375 kPa), or at least about 1500 psig (about 10444
kPa), or at least about 2000 psig (about 13891 kPa).
[0095] As also indicated above, the pressurized carbon dioxide
stream (89), which will typically be in a supercritical fluid
state, serves to enhance production of a hydrocarbon fluid (82)
from a production well (600) through a combination of mechanisms
typically involving a repressurization of the underground reservoir
and a viscosity reduction of the trapped hydrocarbon (improving
flow properties). Typically, the pressurized carbon dioxide stream
(89) will also be injected into the underground reservoir at a
pressure of at least about 1200 psig (about 8375 kPa), or at least
about 1500 psig (about 10444 kPa), or at least about 2000 psig
(about 13891 kPa).
[0096] As is well-known to those of ordinary skill in the relevant
art, EOR using carbon dioxide and nitrogen can utilize co-injection
(both at the same time in the same location), concurrent injection
(both at the same time at different locations), consecutive
injection (one followed by the other in the same or separate
locations) or some combination of these various techniques.
[0097] As is also well-known to those of ordinary skill in the art,
EOR can also involve co-injection, concurrent injection or
consecutive injection of pressurized water, steam and other fluids.
The actual carbon dioxide/nitrogen-based EOR process utilized is
not critical to the present invention in its broadest sense.
[0098] The resulting hydrocarbon-containing fluid (82) is produced
and recovered through a hydrocarbon production well (600) (one or
more). The produced hydrocarbon-containing fluid (82) will
typically contain liquid and gas hydrocarbon components, as well as
other liquid and gaseous components depending on the hydrocarbon
reservoir and EOR conditions. The liquid hydrocarbon component can
generally be considered as a crude oil, while the gaseous
hydrocarbon component will typically comprise hydrocarbons that are
gases at ambient conditions, such as methane, ethane, propane,
propylene and butane (typical components of natural gas). Other
typical liquid components include water or brine. The
hydrocarbon-containing fluid (82) may also comprise carbon dioxide,
and may comprise other gaseous components such as hydrogen sulfide
(from a sour well) and nitrogen. The hydrocarbon-containing fluid
(82) may also include solid carbon and mineral matter.
[0099] The produced hydrocarbon-containing fluid (82) is passed to
a separation device (300) to separate the gaseous components from
the liquid/solid components to generate a gaseous hydrocarbon
product stream (84), a liquid hydrocarbon product stream (85) and,
optionally, a stream (86) containing solids components from the
hydrocarbon-containing fluid (82). The solids may also optionally
be carried with the liquid hydrocarbon product stream (85) for
later separation, or separated out prior to separation device
(300), by well-known techniques such as settling, centrifugation
and/or filtration. In one embodiment, larger/denser solids are
separated in conjunction with separation device (300), and finer
solids that may become entrained in liquid hydrocarbon product
stream (85) are separated subsequently through well-known
techniques such as filtration.
[0100] Suitable separation devices for use as separation device
(300) are well known to those of ordinary skill in the art and
include, for example, single and multistage horizontal separators
and cyclones. The actual separation device utilized is not critical
to the present invention in its broadest sense.
[0101] The liquid hydrocarbon product stream (85), consequently,
will typically comprise at least a predominant portion (or a
substantial portion, or substantially all) of the liquid components
from the hydrocarbon-containing fluid (82) including, for example,
crude oil and water/brine. The liquid hydrocarbon product stream
(85) can subsequently be processed to separate out the water and
other contaminants, then further processed (e.g., refined) to a
variety of end products or for a variety of end uses, as is
well-known to those or ordinary skill in the relevant art.
[0102] If a stream (86) containing solids components is present,
that will typically be removed from separation device (300) as a
concentrated slurry or with some portion of the liquid content of
the hydrocarbon-containing fluid (82). Oil that may be withdrawn
with the solids in stream (86) can be recovered from the solids via
washing or other techniques well-known to those of ordinary skill
in the relevant art.
[0103] The resulting gaseous hydrocarbon product stream (84)
exiting separation device (300) typically comprises at least a
substantial portion (or substantially all) of the gaseous
components from the hydrocarbon-containing fluid (82), including at
least a substantial portion (or substantially all) of the gaseous
hydrocarbons (and carbon dioxide to the extent present) from the
hydrocarbon-containing fluid (82). The gaseous hydrocarbon product
stream (84) may also comprise minor amounts of water vapor (which
should be substantially removed prior to further treatment, for
example, in acid gas removal unit (200) as discussed below) as well
as other contaminants if present, such as hydrogen sulfide.
[0104] If the hydrocarbon-containing fluid (82) contains, e.g.,
more than contaminant amounts of acid gases such as carbon dioxide,
the resulting gaseous hydrocarbon stream (84) will contain a
substantial portion (or substantially all) of the acid gases, and
in one embodiment will be subject to acid gas removal to remove and
recover the acid gases.
[0105] All or a portion of the gaseous hydrocarbon product stream
(84) exiting separation device (300) may be combined with a
synthesis gas stream (50), or otherwise co-processed with synthesis
gas stream (50) in an acid gas removal unit (200) as discussed
below. Prior to combination with synthesis gas stream (50) or
co-processing in acid gas removal unit (200), gaseous hydrocarbon
product stream (84) may optionally be compressed or heated (not
depicted) to temperature and pressure conditions suitable for
combination or other downstream processing as further described
below.
[0106] All or a portion of the gaseous hydrocarbon product stream
(84) may, in addition or alternatively, be combusted in a power
block (760a), for example, for electrical power (79a) and/or steam
generation. An oxygen-rich gas stream (14c) that comprises at least
a portion of oxygen-rich stream (14) from air separation unit (800)
may be utilized in power block (760a) as discussed below.
Synthesis Gas Generation (100)
[0107] Synthesis gas stream (50) contains (i) carbon dioxide, and
(ii) at least one of hydrogen and methane. The actual composition
of synthesis gas stream (50) will depend on the synthesis gas
process and carbonaceous feedstock utilized to generate the stream,
including any gas processing that may occur before acid gas removal
unit (200) or optional combination with gaseous hydrocarbon stream
(84).
[0108] In one embodiment, synthesis gas stream (50) comprises
carbon dioxide and hydrogen. In another embodiment, synthesis gas
stream (50) comprises carbon dioxide and methane. In another
embodiment, synthesis gas stream (50) comprises carbon dioxide,
methane and hydrogen. The synthesis gas stream (50) may also
contain other gaseous components such as, for example, carbon
monoxide, hydrogen sulfide, steam and other gaseous hydrocarbons
again depending on the synthesis gas production process and
carbonaceous feedstock.
[0109] Synthesis gas stream (50) is generated in a synthesis gas
production system (100). Any synthesis gas generating process can
be utilized in the context of the present invention, so long as the
synthesis gas generating process (including gas processing prior to
optional combination with gaseous hydrocarbon stream (84) or prior
to acid gas removal unit (200)) results in a synthesis gas stream
as required in the context of the present invention. Suitable
synthesis gas processes are generally known to those of ordinary
skill in the relevant art, and many applicable technologies are
commercially available.
[0110] An oxygen-rich gas stream (14a) that comprises at least a
portion of oxygen-rich stream (14) from air separation unit (800)
may optionally be utilized in the synthesis gas production system
(100) as described below.
[0111] Non-limiting examples of different types of suitable
synthesis gas generation processes are discussed below. These may
be used individually or in combination. All synthesis gas
generation process will involve a reactor, which is generically
depicted as (110) in FIGS. 3 and 5, where a carbonaceous feedstock
(10) will be processed to produce synthesis gases, which may be
further treated prior to optional combination with gaseous
hydrocarbon stream (84) and/or prior to acid gas removal unit
(200). General reference can be made to FIGS. 3 and 5 in the
context of the various synthesis gas generating processes described
below.
[0112] Gas-Based Methane Reforming/Partial Oxidation
[0113] In one embodiment, the synthesis gas generating process is
based on a gas-fed methane partial oxidation/reforming process,
such as non-catalytic gaseous partial oxidation, catalytic
authothermal reforming or catalytic stream-methane reforming
process. These processes are generally well-known in the relevant
art. See, for example, Rice and Mann, "Autothermal Reforming of
Natural Gas to Synthesis Gas, Reference: KBR Paper #2031," Sandia
National Laboratory Publication No. SAND2007-2331 (2007); and
Bogdan, "Reactor Modeling and Process Analysis for Partial
Oxidation of Natural Gas", printed by Febodruk, B. V., ISBN:
90-365-2100-9 (2004).
[0114] Technologies and reactors potentially suitable for use in
conjunction with the present invention are commercially available
from Royal Dutch Shell plc, Siemens AG, General Electric Company,
Lurgi AG, Haldor Topsoe A/S, Uhde AG, KBR Inc. and others.
[0115] Referring to FIGS. 3 and 5, these gas-based processes
convert a gaseous methane-containing stream as a carbonaceous
feedstock (10), in a reactor (110) into a syngas (hydrogen plus
carbon monoxide) as synthesis gas stream (50) which, depending on
the specific process, will have differing ratios of hydrogen:carbon
monoxide, will generally contain minor amounts of carbon dioxide,
and may contain minor amounts of other gaseous components such as
steam.
[0116] The methane-containing stream useful in these processes
comprises methane in a predominant amount, and may comprise other
gaseous hydrocarbon and components. Examples of commonly used
methane-containing streams include natural gas and synthetic
natural gas.
[0117] In non-catalytic gaseous partial oxidation and autothermal
reforming, an oxygen-rich gas stream (14a) is fed into the reactor
(110) along with carbonaceous feedstock (10). Optionally, steam
(16) may also be fed into the reactor (110). In steam-methane
reforming, steam (16) is fed into the reactor along with the
carbonaceous feedstock (10). In some cases, minor amounts of other
gases such as carbon dioxide, hydrogen and/or nitrogen may also be
fed in the reactor (110).
[0118] Reaction and other operating conditions, and equipment and
configurations, of the various reactors and technologies are in a
general sense known to those of ordinary skill in the relevant art,
and are not critical to the present invention in its broadest
sense.
[0119] Solids/Liquids-Based Gasification to Syngas
[0120] In another embodiment, the synthesis gas generating process
is based on a non-catalytic thermal gasification process, such as a
partial oxidation gasification process (like an oxygen-blown
gasifier), where a non-gaseous (liquid, semi-solid and/or solid)
hydrocarbon is utilized as the carbonaceous feedstock (10). A wide
variety of biomass and non-biomass materials (as described above)
can be utilized as the carbonaceous feedstock (10) in these
processes.
[0121] Oxygen-blown solids/liquids gasifiers potentially suitable
for use in conjunction with the present invention are, in a general
sense, known to those of ordinary skill in the relevant art and
include, for example, those based on technologies available from
Royal Dutch Shell plc, ConocoPhillips Company, Siemens AG, Lurgi AG
(Sasol), General Electric Company and others. Other potentially
suitable syngas generators are disclosed, for example, in
US2009/0018222A1, US2007/0205092A1 and U.S. Pat. No. 6,863,878.
[0122] These processes convert a solid, semi-solid and/or liquid
carbonaceous feedstock (10), in a reactor (110) such as an
oxygen-blown gasifier, into a syngas (hydrogen plus carbon
monoxide) as synthesis gas stream (50) which, depending on the
specific process and carbonaceous feedstock, will have differing
ratios of hydrogen:carbon monoxide, will generally contain minor
amounts of carbon dioxide, and may contain minor amounts of other
gaseous components such as methane, steam, hydrogen sulfide, sulfur
oxides and nitrogen oxides.
[0123] In certain of these processes, an oxygen-rich gas stream
(14a) is fed into the reactor (110) along with the carbonaceous
feedstock (10). Optionally, steam (16) may also be fed into the
reactor (110), as well as other gases such as carbon dioxide,
hydrogen, methane and/or nitrogen.
[0124] In certain of these processes, steam (16) may be utilized as
an oxidant at elevated temperatures in place of all or a part of
the oxygen-rich gas stream (14a).
[0125] The gasification in the reactor (110) will typically occur
in a fluidized bed of the carbonaceous feedstock (10) that is
fluidized by the flow of the oxygen-rich gas stream (14a), steam
(16) and/or other fluidizing gases (like carbon dioxide and/or
nitrogen) that may be fed to reactor (110).
[0126] Typically, thermal gasification is a non-catalytic process,
so no gasification catalyst needs to be added to the carbonaceous
feedstock (10) or into the reactor (110); however, a catalyst that
promotes syngas formation may be utilized.
[0127] These thermal gasification processes are typically operated
under high temperature and pressure conditions, and may run under
slagging or non-slagging operating conditions depending on the
process and carbonaceous feedstock.
[0128] Reaction and other operating conditions, and equipment and
configurations, of the various reactors and technologies are in a
general sense known to those of ordinary skill in the relevant art,
and are not critical to the present invention in its broadest
sense.
[0129] Catalytic Gasification/Hydromethanation to a
Methane-Enriched Gas
[0130] In another alternative embodiment, the synthesis gas
generating process is a catalytic gasification/hydromethanation
process, in which gasification of a non-gaseous carbonaceous
feedstock (10) takes place in a reactor (110) in the presence of
steam and a catalyst to result in a methane-enriched gas stream as
the synthesis gas stream (50), which typically comprises methane,
hydrogen, carbon monoxide, carbon dioxide and steam.
[0131] The hydromethanation of a carbon source to methane typically
involves four concurrent reactions:
Steam carbon: C+H.sub.2O.fwdarw.CO+H.sub.2 (I)
Water-gas shift: CO+H.sub.2O.fwdarw.H.sub.2+CO.sub.2 (II)
CO Methanation: CO+3H.sub.2.fwdarw.CH.sub.4+H.sub.2O (III)
Hydro-gasification: 2H.sub.2+C.fwdarw.CH.sub.4 (IV)
[0132] In the hydromethanation reaction, the first three reactions
(I-III) predominate to result in the following overall
reaction:
2C+2H.sub.2O.fwdarw.CH.sub.4+CO.sub.2 (V).
[0133] The overall reaction is essentially thermally balanced;
however, due to process heat losses and other energy requirements
(such as required for evaporation of moisture entering the reactor
with the feedstock), some heat must be added to maintain the
thermal balance.
[0134] The reactions are also essentially syngas (hydrogen and
carbon monoxide) balanced (syngas is produced and consumed);
therefore, as carbon monoxide and hydrogen are withdrawn with the
product gases, carbon monoxide and hydrogen need to be added to the
reaction as required to avoid a deficiency.
[0135] In order to maintain the net heat of reaction as close to
neutral as possible (only slightly exothermic or endothermic), and
maintain the syngas balance, a superheated gas stream of steam (16)
and syngas (12) (carbon monoxide and hydrogen) is often fed to the
reactor (110) (separately or in combination). Frequently, the
carbon monoxide and hydrogen streams are recycle streams separated
from the product gas, and/or are provided by reforming a portion of
the product methane. Optionally, all or a portion of the syngas can
be generated in situ by feeding an oxygen-rich stream (14a)
directly into reactor (110).
[0136] The carbonaceous feedstocks useful in these processes
include, for example, a wide variety of biomass and non-biomass
materials.
[0137] Catalysts utilized in these processes include, for example,
alkali metals, alkaline earth metals and transition metals, and
compounds, mixtures and complexes thereof.
[0138] The temperature and pressure operating conditions in a
catalytic gasification/hydromethanation process are typically
milder (lower temperature and pressure) than a non-catalytic
gasification process, which can sometimes have advantages in terms
of cost and efficiency.
[0139] Catalytic gasification/hydromethanation processes and
conditions are disclosed, for example, in U.S. Pat. No. 3,828,474,
U.S. Pat. No. 3,998,607, U.S. Pat. No. 4,057,512, U.S. Pat. No.
4,092,125, U.S. Pat. No. 4,094,650, U.S. Pat. No. 4,204,843, U.S.
Pat. No. 4,468,231, U.S. Pat. No. 4,500,323, U.S. Pat. No.
4,541,841, U.S. Pat. No. 4,551,155, U.S. Pat. No. 4,558,027, U.S.
Pat. No. 4,606,105, U.S. Pat. No. 4,617,027, U.S. Pat. No.
4,609,456, U.S. Pat. No. 5,017,282, U.S. Pat. No. 5,055,181, U.S.
Pat. No. 6,187,465, U.S. Pat. No. 6,790,430, U.S. Pat. No.
6,8941,83, U.S. Pat. No. 6,955,695, US2003/0167961A1 and
US2006/0265953A1, as well as in commonly owned US2007/0000177A1,
US2007/0083072A1, US2007/0277437A1, US2009/0048476A1,
US2009/0090056A1, US2009/0090055A1, US2009/0165383A1,
US2009/0166588A1, US2009/0165379A1, US2009/0170968A1,
US2009/0165380A1, US2009/0165381A1, US2009/0165361A1,
US2009/0165382A1, US2009/0169449A1, US2009/0169448A1,
US2009/0165376A1, US2009/0165384A1, US2009/0217582A1,
US2009/0220406A1, US2009/0217590A1, US2009/0217586A1,
US2009/0217588A1, US2009/0218424A1, US2009/0217589A1,
US2009/0217575A1, US2009/0229182A1, US2009/0217587A1,
US2009/0246120A1, US2009/0259080A1, US2009/0260287A1,
US2009/0324458A1, US2009/0324459A1, US2009/0324460A1,
US2009/0324461A1, US2009/0324462A1, US2010/0121125A1,
US2010/0120926A1, US2010/0071262A1, US2010/0076235A1,
US2010/0179232A1, US2010/0120926A1, US2010/0071262A1,
US2010/0076235A1, US2010/0179232A1, US2010/0168495A1 and
US2010/0168494A1; U.S. patent application Ser. Nos. 12/778,538
(attorney docket no. FN-0047 US NP1, entitled PROCESS FOR
HYDROMETHANATION OF A CARBONACEOUS FEEDSTOCK), 12/778,548 (attorney
docket no. FN-0048 US NP1, entitled PROCESSES FOR HYDROMETHANATION
OF A CARBONACEOUS FEEDSTOCK) and 12/778,552 (attorney docket no.
FN-0049 US NP1, entitled PROCESSES FOR HYDROMETHANATION OF A
CARBONACEOUS FEEDSTOCK), each of which was filed 12 May 2010; U.S.
patent application Ser. Nos. 12/851,864 (attorney docket no.
FN-0050 US NP1, entitled PROCESS FOR HYDROMETHANATION OF A
CARBONACEOUS FEEDSTOCK), which was filed 6 Aug. 2010; and U.S.
patent applications Ser. Nos. 12/882,415 (attorney docket no.
FN-0051 US NP1, entitled PROCESS FOR HYDROMETHANATION OF A
CARBONACEOUS FEEDSTOCK), 12/882,412 (attorney docket no. FN-0052 US
NP1, entitled INTEGRATED HYDROMETHANATION COMBINED CYCLE PROCESS),
12/882,408 (attorney docket no. FN-0053 US NP1, entitled INTEGRATED
HYDROMETHANATION COMBINED CYCLE PROCESS) and 12/882,417 (attorney
docket no. FN-0054 US NP1, entitled PROCESS FOR HYDROMETHANATION OF
A CARBONACEOUS FEEDSTOCK), each of which was filed 15 Sep.
2010.
[0140] General reaction and other operating conditions of the
various catalytic gasification/hydromethanation reactors and
technologies can be found from the above references, and are not
critical to the present invention in its broadest sense.
Heat Exchange (140)
[0141] All of the above described synthesis gas generation
processes typically will generate a synthesis gas stream (50) of a
temperature higher than suitable for feeding downstream gas
processes (including acid gas removal unit (200)) and/or combining
with gaseous hydrocarbon stream (84), so upon exit from reactor
(110) the synthesis gas stream (50) is typically passed through a
heat exchanger unit (140) to remove heat energy and generate a
cooled synthesis gas stream (52).
[0142] The heat energy recovered in heat exchanger unit (140) can
be used, for example, to generate steam and/or superheat various
process streams, as will be recognized by a person of ordinary
skill in the art. Any steam generated can be used, for example, for
internal process requirements and/or to generate electrical
power.
[0143] In one embodiment, the resulting cooled synthesis gas stream
(52) will typically exit heat exchanger unit (140) at a temperature
ranging from about 450.degree. F. (about 232.degree. C.) to about
1100.degree. F. (about 593.degree. C.), more typically from about
550.degree. F. (about 288.degree. C.) to about 950.degree. F.
(about 510.degree. C.), and at a pressure suitable for subsequent
acid gas removal processing (taking into account any intermediate
processing). Typically, this pressure will be from about 50 psig
(about 446 kPa) to about 800 psig (about 5617 kPa), more typically
from about 400 psig (about 2860 kPa) to about 600 psig (about 4238
kPa).
Gas Treatment Prior to Acid Gas Removal
[0144] Synthesis gas stream (50) and gaseous hydrocarbon stream
(84) may be processed separately, or may optionally be combined at
various points and individually or co-processed in various
treatment processes, or optionally combined and co-treated at or in
acid gas removal unit (200). Specific embodiments where synthesis
gas stream (50) and gaseous hydrocarbon stream (84) are combined
and/or co-processed are depicted in FIGS. 2-5. The combination
point and processing variations will be primarily dependent on the
composition, temperature and pressure of the two streams, and any
desired end products.
[0145] Processing options prior to acid gas removal typically
include, for example, one or more of sour shift (700) (water gas
shift), contaminant removal (710) and dehydration (720). While
these intermediate processing steps can occur in any order,
dehydration (720) will usually occur just prior to acid gas removal
(last in the series), as a substantial portion of any water in
synthesis gas stream (50) and gaseous hydrocarbon stream (84)
desirably should be removed prior to treatment in acid gas removal
unit (200).
[0146] In one embodiment as depicted in FIGS. 2 and 3, synthesis
gas stream (50) and gaseous hydrocarbon stream (84) are combined
prior to acid gas removal unit (200) to generate a combined gas
stream (60). In one specific embodiment, synthesis gas stream (50)
and gaseous hydrocarbon stream (84) are combined prior to
dehydration (720). In another specific embodiment, synthesis gas
stream (50) and gaseous hydrocarbon stream (84) are separately
dehydrated (720 and 720a) and combined before or during acid gas
removal.
[0147] Combination of the two streams may also require compression
or expansion of one or both of the streams. Typically, the gaseous
hydrocarbon stream (84) will require at least some compression
prior to combination with synthesis gas stream (50).
[0148] In another embodiment as depicted in FIGS. 4 and 5,
synthesis gas stream (50) and gaseous hydrocarbon stream (84) are
co-processed within acid gas removal unit (200), as discussed in
more detail below.
Sour Shift (700)
[0149] In certain embodiments, particularly where a stream contains
appreciable amounts of carbon monoxide, and it is desired to
maximize hydrogen and/or carbon dioxide production, all or a part
of such stream (such as synthesis gas stream (50)) can be supplied
to a sour shift reactor (700).
[0150] In sour shift reactor (700), the gases undergo a sour shift
reaction (also known as a water-gas shift reaction, see formula
(II) above) in the presence of an aqueous medium (such as steam) to
convert at least a predominant portion (or a substantial portion,
or substantially all) of the CO to CO.sub.2, which also increases
the fraction of H.sub.2 in order to produce a hydrogen-enriched
stream (54).
[0151] A sour shift process is described in detail, for example, in
U.S. Pat. No. 7,074,373. The process involves adding water, or
using water contained in the gas, and reacting the resulting
water-gas mixture adiabatically over a steam reforming catalyst.
Typical steam reforming catalysts include one or more Group VIII
metals on a heat-resistant support.
[0152] Methods and reactors for performing the sour gas shift
reaction on a CO-containing gas stream are well known to those of
skill in the art. Suitable reaction conditions and suitable
reactors can vary depending on the amount of CO that must be
depleted from the gas stream. In some embodiments, the sour gas
shift can be performed in a single stage within a temperature range
from about 100.degree. C., or from about 150.degree. C., or from
about 200.degree. C., to about 250.degree. C., or to about
300.degree. C., or to about 350.degree. C. In these embodiments,
the shift reaction can be catalyzed by any suitable catalyst known
to those of skill in the art. Such catalysts include, but are not
limited to, Fe.sub.2O.sub.3-based catalysts, such as
Fe.sub.2O.sub.3--Cr.sub.2O.sub.3 catalysts, and other transition
metal-based and transition metal oxide-based catalysts. In other
embodiments, the sour gas shift can be performed in multiple
stages. In one particular embodiment, the sour gas shift is
performed in two stages. This two-stage process uses a
high-temperature sequence followed by a low-temperature sequence.
The gas temperature for the high-temperature shift reaction ranges
from about 350.degree. C. to about 1050.degree. C. Typical
high-temperature catalysts include, but are not limited to, iron
oxide optionally combined with lesser amounts of chromium oxide.
The gas temperature for the low-temperature shift ranges from about
150.degree. C. to about 300.degree. C., or from about 200.degree.
C. to about 250.degree. C. Low-temperature shift catalysts include,
but are not limited to, copper oxides that may be supported on zinc
oxide or alumina. Suitable methods for the sour shift process are
described in previously incorporated US2009/0246120A1.
[0153] The sour shift reaction is exothermic, so it is often
carried out with a heat exchanger (not depicted) to permit the
efficient use of heat energy. Shift reactors employing these
features are well known to those of skill in the art. Recovered
heat energy can be used, for example, to generate steam, superheat
various process streams and/or preheat boiler feed water for use in
other steam generating operations. An example of a suitable shift
reactor is illustrated in previously incorporated U.S. Pat. No.
7,074,373, although other designs known to those of skill in the
art are also effective.
[0154] If sour shift is present and it is desired to retain some
carbon monoxide content, a portion of the stream can be split off
to bypass sour shift reactor (700) and be combined with
hydrogen-enriched stream (54) at some point prior to acid gas
removal unit (200). This is particularly useful when it is desired
to recover a separate methane by-product, as the retained carbon
monoxide can be subsequently methanated as discussed below.
Contaminant Removal (710)
[0155] As is familiar to those skilled in the art, the
contamination levels of synthesis gas stream (50) will depend on
the nature of the carbonaceous feedstock and the synthesis gas
generation conditions. For example, petcoke and certain coals can
have high sulfur contents, leading to higher sulfur oxide (SOx),
H.sub.2S and/or COS contamination. Certain coals can contain
significant levels of mercury which can be volatilized during the
synthesis gas generation. Other feedstocks can be high in nitrogen
content, leading to ammonia, nitrogen oxides (NOx) and/or
cyanides.
[0156] Some of these contaminants are typically removed in acid gas
removal unit (200), such as H.sub.2S and COS. Others such as
ammonia and mercury, typically require removal prior to acid gas
removal unit (200).
[0157] When present, contaminant removal of a particular
contaminant should remove at least a substantial portion (or
substantially all) of that contaminant from the so-treated cleaned
gas stream (56), typically to levels at or lower than the
specification limits for the desired acid gas removal unit (200),
or the desired end product.
[0158] While in FIG. 3 it is shown that gaseous hydrocarbon stream
(84) and cooled synthesis gas stream (54) can be combined
subsequent to contaminant removal unit (700), this is only shown
for exemplification, as the two streams may be combined prior to
contaminant removal unit (710), or treated separately for
contaminant removal as needed and subsequently combined.
[0159] Contaminant removal process are in a general sense well know
to those of ordinary skill in the relevant art, as exemplified in
many of the previously-incorporated references.
Dehydration (720)
[0160] In addition, prior to the acid gas removal unit (200), the
synthesis gas stream (50) and gaseous hydrocarbon stream (84),
individually or in combination, should be treated to reduce
residual water content via a dehydration unit (720) (and (720a) if
present) to produce a dehydrated stream (58) (and (58a) if
dehydration unit (720a) is present).
[0161] Examples of suitable dehydration units include a knock-out
drum or similar water separation device, and/or water absorption
processes such as glycol treatment.
[0162] Such dehydration units and processes again are in a general
sense well known to those of ordinary skill in the relevant
art.
Acid Gas Removal (200)
[0163] In accordance with the present invention, at least the
synthesis gas stream (50) (or a derivative stream resulting from
intermediate treatment) is processed in an acid gas removal unit
(200) to remove carbon dioxide and other acid gases (such as
hydrogen sulfide if present), and generate a carbon dioxide-rich
stream (87) and an acid gas-depleted synthesis gas stream as the
acid gas-depleted product gas stream (38).
[0164] Optionally, the synthesis gas stream (50) and the gaseous
hydrocarbon product stream (84) (or derivative streams resulting
from intermediate treatment) are co-processed in an acid gas
removal unit (200) to remove carbon dioxide and other acid gases
(such as hydrogen sulfide if present), and generate the acid
gas-depleted product gas steam (38), which can be a single stream
generated from a combination of, or individual stream derived from,
the synthesis gas stream (50) and the gaseous hydrocarbon product
stream (84) (or derivative streams resulting from intermediate
treatment). See, for example, previously incorporated U.S. patent
application Ser. Nos. 12/906,552 and 12/906,547.
[0165] As set forth in FIGS. 2 and 3, and discussed further below,
synthesis gas stream (50) and the gaseous hydrocarbon product
stream (84) are co-processed to generate a carbon dioxide-rich
stream (87) and a combined acid-gas depleted gaseous hydrocarbon
product stream (80) (as acid gas-depleted product gas steam
(38)).
[0166] As set forth in FIGS. 4 and 5, and discussed further below,
synthesis gas stream (50) and the gaseous hydrocarbon product
stream (84) are co-processed to generate a carbon dioxide-rich
stream (87), and an individual acid gas-depleted gaseous
hydrocarbon product stream (31) and an individual acid gas-depleted
synthesis gas stream (30) (acid gas-depleted product gas steam
(38)).
[0167] Acid gas removal processes typically involve contacting a
gas stream with a solvent such as monoethanolamine, diethanolamine,
methyldiethanolamine, diisopropylamine, diglycolamine, a solution
of sodium salts of amino acids, methanol, hot potassium carbonate
or the like to generate CO.sub.2 and/or H.sub.2S laden absorbers.
One method can involve the use of Selexol.RTM. (UOP LLC, Des
Plaines, Ill. USA) or Rectisol.RTM. (Lurgi AG, Frankfurt am Main,
Germany) solvent having two trains; each train containing an
H.sub.2S absorber and a CO.sub.2 absorber.
[0168] One method for removing acid gases is described in
previously incorporated US2009/0220406A1.
[0169] At least a substantial portion (e.g., substantially all) of
the CO.sub.2 and/or H.sub.2S (and other remaining trace
contaminants) should be removed via the acid gas removal processes.
"Substantial" removal in the context of acid gas removal means
removal of a high enough percentage of the component such that a
desired end product can be generated. The actual amounts of removal
may thus vary from component to component. Desirably, only trace
amounts (at most) of H.sub.2S should be present in the acid
gas-depleted product stream, although higher amounts of CO.sub.2
may be tolerable depending on the desired end product.
[0170] Typically, at least about 85%, or at least about 90%, or at
least about 92%, of the CO.sub.2, and at least about 95%, or at
least about 98%, or at least about 99.5%, of the H.sub.2S, should
be removed, based on the amount of those components contained in
the streams fed to the acid gas removal unit (200).
[0171] Any recovered H.sub.2S (88) from the acid gas removal can be
converted to elemental sulfur by any method known to those skilled
in the art, including the Claus process. Sulfur can be recovered as
a molten liquid.
[0172] It is, however, not necessary for EOR purposes to separate
CO.sub.2 and H.sub.2S. In one embodiment, consequently, the carbon
dioxide-rich stream (87) resulting from acid gas removal is a sour
CO.sub.2 stream, as disclosed in previously incorporated U.S.
patent application Ser. No. ______ (attorney docket no. FN-0058 US
NP1, entitled INTEGRATED ENHANCED OIL RECOVERY PROCESS), filed
concurrently herewith.
Embodiment of FIGS. 2 and 3
[0173] In this embodiment, as indicated previously, the synthesis
gas stream (50) and the gaseous hydrocarbon stream (84) may be
combined at various stages prior to the acid gas removal unit (200)
to create a combined gas stream (60) which is fed into acid gas
removal unit (200), or the two streams may be combined at some
point in the acid gas removal unit (200) and co-processed.
[0174] The resulting acid gas-depleted gaseous hydrocarbon product
stream (80) will generally comprise one or both of CH.sub.4 and
H.sub.2, other gaseous hydrocarbons from the gaseous hydrocarbon
stream (84), and optionally CO (for the downstream methanation),
and typically no more than contaminant amounts of CO.sub.2,
H.sub.2O, H.sub.2S and other contaminants.
[0175] A carbon dioxide-rich stream (87) is also generated
containing a substantial portion of carbon dioxide from both
synthesis gas stream (50) and gaseous hydrocarbon stream (84). If
one or both of synthesis gas stream (50) and gaseous hydrocarbon
stream (84) contain other acid gas contaminants, such as hydrogen
sulfide, then an additional stream may be generated, such as
hydrogen sulfide stream (88).
[0176] Alternatively, as mentioned above, other acid gases can
remain in carbon dioxide-rich stream (87), particularly in the case
where carbon dioxide-rich stream (87) is used for EOR, in which
case carbon dioxide-rich stream (87) will be a sour CO.sub.2
stream.
Embodiment of FIGS. 4 and 5
[0177] In this embodiment, the synthesis gas stream (50) and the
gaseous hydrocarbon stream (84) (or derivative streams resulting
from intermediate treatment) are co-processed in an acid gas
removal unit to remove carbon dioxide and other acid gases (such as
hydrogen sulfide if present), and generate a carbon dioxide-rich
stream (87), an acid gas-depleted gaseous hydrocarbon product
stream (31) and an acid gas-depleted synthesis gas stream (30).
[0178] In the acid gas removal unit, the synthesis gas stream (50)
and the gaseous hydrocarbon stream (84) are first individually
treated in a second acid gas absorber unit (210) and a first acid
gas absorber unit (230), respectively, to generate a separate acid
gas-depleted synthesis gas stream (30) and second acid gas-rich
absorber stream (35), and a separate acid gas-depleted gaseous
hydrocarbon product stream (31) and first acid gas-rich absorber
stream (36).
[0179] The resulting acid gas-depleted gaseous hydrocarbon product
stream (31) will generally comprise CH.sub.4 and other gaseous
hydrocarbons from the gaseous hydrocarbon stream (84), and
typically no more than contaminant amounts of CO.sub.2, H.sub.2O,
H.sub.2S and other contaminants. The resulting acid gas-depleted
synthesis gas stream (30) will generally comprise one or both of
CH.sub.4 and H.sub.2, and optionally CO (for the downstream
methanation), and typically no more than contaminant amounts of
CO.sub.2, H.sub.2O, H.sub.2S and other contaminants.
[0180] The resulting acid gas-depleted gaseous hydrocarbon product
stream (31) and an acid gas-depleted synthesis gas stream (30) may
be co-processed or separately processed as described further
below.
[0181] The resulting first acid gas-rich absorber stream (36) and
second acid gas-rich absorber stream (35) are co-processed in an
absorber regeneration unit (250) to ultimately result in an acid
gas stream containing the combined acid gases (and other
contaminants) removed from both synthesis gas stream (50) and
gaseous hydrocarbon stream (84). First acid gas-rich absorber
stream (36) and second acid gas-rich absorber stream (35) may be
combined prior to or within absorber regeneration unit (250) for
co-processing. An acid gas-lean absorber stream (70) is generated,
which can be recycled back to one or both of first acid gas
absorber unit (230) and second acid gas absorber unit (210) along
with make-up absorber as required.
[0182] A carbon dioxide-rich stream (87) is also generated
containing a substantial portion of carbon dioxide from both
synthesis gas stream (50) and gaseous hydrocarbon stream (84). If
one or both of synthesis gas stream (50) and gaseous hydrocarbon
stream (84) contain other acid gas contaminants, such as hydrogen
sulfide, then an additional stream may be generated, such as
hydrogen sulfide stream (88).
[0183] Alternatively, as mentioned above, other acid gases can
remain in carbon dioxide-rich stream (87), particularly in the case
where carbon dioxide-rich stream (87) is used for EOR, in which
case carbon dioxide-rich stream (87) will be a sour CO.sub.2
stream.
Use of Carbon Dioxide-Rich Stream (87) for EOR
[0184] In one embodiment, carbon dioxide-rich stream (87) is used
for EOR.
[0185] In such embodiment, the recovered carbon dioxide-rich
recycle stream (87) is in whole or in part compressed via
compressor (400) to generate pressurized carbon dioxide stream (89)
for the EOR portion of the process. A CO.sub.2 product stream (90)
can also optionally be split off of pressurized carbon dioxide
stream (89).
[0186] Suitable compressors for compressing carbon dioxide-rich
recycle stream (87) to appropriate pressures and conditions for EOR
are in a general sense well-known to those of ordinary skill in the
relevant art.
Optional Further Processing of Acid Gas-Depleted Product
Streams
[0187] All or a portion the of the acid gas-depleted product gas
steam (38) (FIG. 1), acid gas-depleted gaseous hydrocarbon product
stream (80) (FIGS. 2 and 3), or the acid gas-depleted synthesis gas
stream (30) and acid gas-depleted gaseous hydrocarbon product
stream (31) (FIGS. 4 and 5) (individually, or combined in whole or
in part), may be processed to end products and/or for end uses as
are well known to those of ordinary skill in the relevant art.
[0188] Non-limiting options are discussed below in reference to
FIGS. 3 and 5. Although FIGS. 3 and 5 only depict some of the
options as applied to acid gas-depleted gaseous hydrocarbon product
stream (80) and acid gas-depleted synthesis gas stream (30), these
options (and others) may be applied to acid gas-depleted gaseous
hydrocarbon product stream (31) (or a combined stream) where
appropriate.
[0189] Hydrogen Separation (730)
[0190] Hydrogen may be separated from all or a portion of the acid
gas-depleted gaseous hydrocarbon product stream (80) or acid
gas-depleted synthesis gas stream (30) according to methods known
to those skilled in the art, such as cryogenic distillation, the
use of molecular sieves, gas separation (e.g., ceramic or
polymeric) membranes, and/or pressure swing adsorption (PSA)
techniques.
[0191] In one embodiment, a PSA device is utilized for hydrogen
separation. PSA technology for separation of hydrogen from gas
mixtures containing methane (and optionally carbon monoxide) is in
general well-known to those of ordinary skill in the relevant art
as disclosed, for example, in U.S. Pat. No. 6,379,645 (and other
citations referenced therein). PSA devices are generally
commercially available, for example, based on technologies
available from Air Products and Chemicals Inc. (Allentown, Pa.),
UOP LLC (Des Plaines, Ill.) and others.
[0192] In another embodiment, a hydrogen membrane separator can be
used followed by a PSA device.
[0193] Such separation provides a high-purity hydrogen product
stream (72) and a hydrogen-depleted gas stream (74).
[0194] The recovered hydrogen product stream (72) preferably has a
purity of at least about 99 mole %, or at least 99.5 mole %, or at
least about 99.9 mole %.
[0195] The recovered hydrogen can be used, for example, as an
energy source and/or as a reactant. For example, the hydrogen can
be used as an energy source for hydrogen-based fuel cells, or for
power and/or steam generation, for example, in power block (760).
The hydrogen can also be used as a reactant in various
hydrogenation processes, such as found in the chemical and
petroleum refining industries.
[0196] The hydrogen-depleted gas stream (74) will substantially
comprise light hydrocarbons, such as methane, with optional minor
amounts of carbon monoxide (depending primarily on the extent of
the sour shift reaction and bypass), carbon dioxide (depending
primarily on the effectiveness of the acid gas removal process) and
hydrogen (depending primarily on the extent and effectiveness of
the hydrogen separation technology), and can be further
processed/utilized as described below.
[0197] Methanation (740)
[0198] If the acid gas-depleted gaseous hydrocarbon product stream
(80) or the acid gas-depleted synthesis gas stream (30) (or the
hydrogen-depleted sweetened gas stream (74)) contains carbon
monoxide and hydrogen, all or part of the stream may be fed to a
(trim) methanation unit (740) to generate additional methane from
the carbon monoxide and hydrogen (see formula (III) above),
resulting in a methane-enriched gas stream (75).
[0199] The methanation reaction can be carried out in any suitable
reactor, e.g., a single-stage methanation reactor, a series of
single-stage methanation reactors or a multistage reactor.
Methanation reactors include, without limitation, fixed bed, moving
bed or fluidized bed reactors. See, for instance, U.S. Pat. No.
3,958,957, U.S. Pat. No. 4,252,771, U.S. Pat. No. 3,996,014 and
U.S. Pat. No. 4,235,044. Methanation reactors and catalysts are
generally commercially available. The catalyst used in the
methanation, and methanation conditions, are generally known to
those of ordinary skill in the relevant art, and will depend, for
example, on the temperature, pressure, flow rate and composition of
the incoming gas stream.
[0200] As the methanation reaction is exothermic, the
methane-enriched gas stream (75) may be, for example, further
provided to a heat exchanger unit (750). While the heat exchanger
unit (750) is depicted as a separate unit, it can exist as such
and/or be integrated into methanation unit (740), thus being
capable of cooling the methanation unit (740) and removing at least
a portion of the heat energy from the methane-enriched stream (75)
to reduce the temperature and generate a cooled methane-enriched
stream (76). The recovered heat energy can be utilized, for
example, to generate a process steam stream from a water and/or
steam source.
[0201] All or part of the methane-enriched stream (75) can be
recovered as a methane product stream (77) or, it can be further
processed, when necessary, to separate and recover CH.sub.4 by any
suitable gas separation method known to those skilled in the art
including, but not limited to, cryogenic distillation and the use
of molecular sieves or gas separation (e.g., ceramic)
membranes.
Pipeline-Quality Natural Gas
[0202] In certain embodiments, the acid gas-depleted hydrocarbon
stream (80), or the acid gas-depleted synthesis gas stream (30), or
the acid gas-depleted gaseous hydrocarbon product stream (31), or a
combination of the acid gas-depleted synthesis gas stream (30) and
the acid gas-depleted gaseous hydrocarbon product stream (31), or
the hydrogen-depleted gas stream (74), and/or the methane-enriched
gas stream (75), are "pipeline-quality natural gas". A
"pipeline-quality natural gas" typically refers to a natural gas
that is (1) within .+-.5% of the heating value of pure methane
(whose heating value is 1010 btu/ft.sup.3 under standard
atmospheric conditions), (2) substantially free of water (typically
a dew point of about -40.degree. C. or less), and (3) substantially
free of toxic or corrosive contaminants.
Uses of Gaseous Hydrocarbon Product Streams
[0203] All or a portion of the aforementioned streams can, for
example, be utilized for combustion and/or steam generation, for
example, in a power generation block (760) to produce electrical
power (79) which may be either utilized within the plant or can be
sold onto the power grid.
[0204] All or a portion of these streams can also be used as a
recycle hydrocarbon stream (78), for example, for use as
carbonaceous feedstock (10) in a gaseous partial oxidation/methane
reforming process, or for the generation of syngas feed stream (12)
for use in a hydromethanation process (in, for example, a gaseous
partial oxidation/methane reforming process). Both of these uses
can, for example, ultimately result in an optimized production of
hydrogen product stream (72), and carbon dioxide-rich stream
(87).
Power Generation Block (760, 760a)
[0205] The present process, as discussed in detail above, can be
integrated with a power generation block (760, 760a) for the
production of electrical power (79, 79a) as a product of the
integrated process. The power generation block (760, 760a) can be
of a configuration similar to that generally utilized in integrated
gasification combined cycle (IGCC) applications.
[0206] Particularly, the power generation block (760, 760a) can
comprise an air separation unit (800a) for use in generating
oxygen-rich stream (14) and nitrogen-rich stream (17) from an air
stream (18).
[0207] An example of a power generation block suitable for use in
connection with the present invention is depicted in FIG. 6.
Reference is made to power generation block (760) in FIG. 6 and
below, but the discussion is also applicable to power generation
block (760a) as well.
[0208] A combustible gas stream (81) is fed into power generation
block (760). Combustible gas stream (81) is typically a
methane-rich and/or hydrogen-rich gas stream, such as a natural or
synthetic natural gas stream. In various embodiments, combustible
gas stream (81) can comprise all or a portion of one or more of (i)
acid-gas depleted product gas stream (38); (ii) acid-gas depleted
gaseous hydrocarbon product stream (31), (iii) acid gas-depleted
hydrocarbon product stream (80); and/or (iv) a downstream
derivative of (i), (ii) and/or (iii), such as hydrogen product
stream (72), hydrogen-depleted gas stream (74) and/or
methane-enriched gas stream (76).
[0209] As depicted in FIG. 1, one or both of power generation
blocks (760) and (760a) can be present. When power generation block
(760a) is present, the combustible gas stream (81) is gaseous
hydrocarbon stream (84). Power generation block (760a) if present
can have the same or different configuration as power generation
block (760).
[0210] Depending on the pressure of combustible gas stream (81), it
can initially be fed to an expander (987), which can be a first
turbine generator. A first electrical power stream (79b) can be
generated as a result of this decompression.
[0211] The decompressed combustible gas stream can then be fed to a
combustor (980) along with a compressed air stream (not depicted)
or a compressed oxygen-rich stream (14b), where it is combusted to
produce combustion gases (83) at an elevated temperature and
pressure. In one embodiment, compressed oxygen-rich stream (14b)
comprises at least a portion of oxygen-rich stream (14). Suitable
combustors are generally well-known to those of ordinary skill in
the relevant art.
[0212] The resulting combustion gases (83) are fed to a second
turbine generator (982) where a second electrical power stream
(79c) is generated.
[0213] The second turbine generator (982) can be coupled
(mechanically and/or electrically) to a compressor for compressing,
for example, an air stream (18) to generate compressed air stream
for use in combustor (980). In one embodiment, as depicted in FIG.
6, compressor is air separation unit (800a) into which air stream
(18) is fed, and oxygen-rich stream (14) and nitrogen-rich stream
(17) are generated. In another embodiment, air separation unit
(800) is operated utilizing electrical power (79) generated in
power generation block (760).
[0214] Combustion gases (83), after passing through second turbine
generator (982), still comprise significant heat energy, and can be
passed to a heat recovery steam generator (984) before exiting the
power generation block (760) as a stack gas stream (96).
[0215] If combustor (980) is fed with substantially pure oxygen as
compressed oxygen-rich stream (14b) and combustible gas stream (81)
is a methane-rich stream, then stack gas stream (96) will comprise
substantially CO.sub.2 and can optionally be processed via acid gas
removal unit (200) to capture the carbon dioxide, or directly
provided to a compressor (such as compressor (400)) for EOR
use.
[0216] A steam stream (91) generated in heat recovery steam
generator (985) can be passed to a third turbine generator (985)
where a third electrical power stream (79d) is generated. A
steam/water stream (98) from third turbine generator (985) is then
passed back to heat recovery steam generator (984) for reheating
and reuse.
[0217] If combustor (980) is fed with substantially pure oxygen as
compressed oxygen-rich stream (14b) and combustible gas stream (81)
is a hydrogen-rich stream, then stack gas stream (96) will comprise
substantially steam which can be recovered and utilized in the
process, for example, directly fed to third turbine generator (985)
for the generation of electrical power.
Air Separation Unit (800)
[0218] Air separation units suitable for use as air separation unit
(800) and (800a) are in general well-known to those of ordinary
skill in the relevant art. Well-know air separation technologies
include, for example, cryogenic distillation, ambient temperature
adsorption and membrane separations.
[0219] Operating conditions, and equipment and configurations, of
the various technologies in order to achieve the desired
oxygen-rich stream (14) and nitrogen-rich stream (17) from air
stream (18) are in a general sense known to those of ordinary skill
in the relevant art, and are not critical to the present invention
in its broadest sense.
[0220] The nitrogen-rich stream (17) is in whole or in part
compressed via compressor (410) to generate pressurized nitrogen
stream (19) for the EOR portion of the process. Suitable
compressors for compressing nitrogen-rich stream (17) to
appropriate pressures and conditions for EOR are in a general sense
well-known to those of ordinary skill in the relevant art.
Examples of Additional Specific Embodiments
[0221] In one embodiment, the synthesis gas stream is produced by a
catalytic steam methane reforming process utilizing a
methane-containing stream as the carbonaceous feedstock.
[0222] In another embodiment, the synthesis gas stream is produced
by a non-catalytic (thermal) gaseous partial oxidation process
utilizing a methane-containing stream as the carbonaceous
feedstock.
[0223] In another embodiment, the synthesis gas stream is produced
by a catalytic autothermal reforming process utilizing a
methane-containing stream as the carbonaceous feedstock.
[0224] The methane-containing stream for use in these processes may
be a natural gas stream, a synthetic natural gas stream or a
combination thereof In one embodiment, the methane-containing
stream comprises all or a portion of the acid gas-depleted gaseous
hydrocarbon product stream (or a derivative of this stream after
downstream processing).
[0225] The resulting synthesis gas stream from these processes will
comprise at least hydrogen and one or both of carbon monoxide and
carbon dioxide, depending on gas processing prior to acid gas
removal.
[0226] In another embodiment, the synthesis gas stream is produced
by a non-catalytic thermal gasification process utilizing a
non-gaseous carbonaceous material as the carbonaceous feedstock,
such as coal, petcoke, biomass and mixtures thereof.
[0227] The resulting synthesis gas stream from this process will
comprise at least hydrogen and one or both of carbon monoxide and
carbon dioxide, depending on gas processing prior to acid gas
removal.
[0228] In another embodiment, the synthesis gas stream is produced
by a catalytic hydromethanation process utilizing a non-gaseous
carbonaceous material as the carbonaceous feedstock, such as coal,
petcoke, biomass and mixtures thereof.
[0229] The resulting synthesis gas stream from this process will
comprise at least methane, hydrogen and carbon dioxide, and
optionally carbon monoxide, depending on gas processing prior to
acid gas removal.
* * * * *
References