Note: Descriptions are shown in the official language in which they were submitted.
AMINE CO2 SEPARATION PROCESS
INTEGRATED WITH HYDROCARBONS PROCESSING
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority to and the benefit of U.S. Application
No. 17/484,068
having a filing date of September 24, 2021, the disclosure of which is
incorporated herein by
reference in its entirety.
FIELD
[0002] This disclosure relates to processes for separating CO2 from a gas
mixture comprising
CO2 and processes for processing hydrocarbons. In particular, this disclosure
relates to an
amine CO2 separation process integrated with an olefins production plant.
BACKGROUND
[0003] Ethylene and propylene (light olefins) are two of the highest volume
petrochemical
products manufactured. The polymer products into which they are converted have
numerous
applications in society ranging from food wrap films that extend produce shelf
life to light-
weight automotive components that contribute to reduced fuel consumption. The
majority of
ethylene and propylene are manufactured from hydrocarbon feedstocks by the so-
called steam-
cracking process in an olefins product plant. In this process the hydrocarbon
feed, in the
presence of steam, is subjected to very high temperatures for very short
reaction times,
producing a mixed product stream rich in ethylene and propylene, but also
containing
molecules ranging from hydrogen to fuel-oil. This mixed product stream is then
immediately
cooled and separated to produce a process gas stream comprising Cl-C4
hydrocarbons
including ethylene and propylene. The process gas stream is then compressed to
a higher
pressure, cooled to a very low temperature in a chill chain, and separated in
distillation columns
to recover, among others, an ethylene product stream and a propylene product
stream. Steam
turbines are typically utilized in the olefins production plant. Other
hydrocarbon processing
plants, such as oil refineries, and the like, also utilizes steam turbines to
drive various rotary
equipment. Historically, to maximize shaft power production, such steam
turbines have been
routinely configured to exhaust a considerable amount of a condensable steam
stream at very
low pressure of below 100 kPa absolute, which is then condensed using a
surface condenser,
resulting in substantial amount of thermal energy released to the atmosphere.
[0004] CO2, a major greenhouse gas in the atmosphere, can be present in
industrial gas
mixtures, e.g., flue gas streams produced from combustion of hydrocarbon-
containing fuel
gases, intermediate gas streams in syngas production processes and H2
production processes.
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Date Recue/Date Received 2022-12-09
Separation and capture of CO2 from these industrial gas mixtures can be
desirable in order to
reduce CO2 emission to the atmosphere. The separated CO2 can be compressed,
liquefied,
transferred, sequestered, stored, or utilized to reduce its climate impact. A
widely used process
for separating CO2 from a CO2-containing gas mixture uses an amine to absorb
the CO2 from
the gas mixture to produce a CO2-rich amine stream, which is then heated in a
regeneration
step to separate CO2 from the amine, thereby producing a CO2 stream and a lean-
amine stream.
Significant volumes of low-pressure steam are generally consumed in the amine
regeneration
step. The lean-amine stream can be recycled to the absorption step.
[0005] There is a need to improve energy efficiency of a hydrocarbon
processing plant such
as an olefins production plant and of an amine CO2 separation process. This
disclosure satisfies
this and other needs.
SUMMARY
[0006] A process for recovering CO2 from a gas mixture comprising CO2 may
utilize an
amine to preferentially absorb the CO2 from the gas mixture to produce a CO2-
rich and amine-
rich mixture, which can be heated in a regeneration step to separate the CO2
from the amine.
In hydrocarbon processing plants, such as refineries and olefins production
plants, steam
turbines may be used to produce shaft power needed to drive certain equipment
such as
compressors and pumps. It has been found that an amine absorption/regeneration
process can
be advantageously integrated with a hydrocarbon processing plant by using
extraction turbine(s)
and/or back-pressure turbine(s) producing an exhaust steam stream and shaft
power. The
exhaust stream has sufficient pressure such that it can be advantageously
supplied to the amine
regeneration step to heat the CO2-rich and amine-rich mixture, and the shaft
power can be used
to drive equipment in the hydrocarbon processing plant. As a result, improved
energy
efficiency can be achieved than previous processes without such integration.
[0007] Thus, a first aspect of this disclosure relates to a process comprising
one or more of
the following: (i) obtaining an exhaust steam stream having an absolute
pressure from 200 kPa
to 1,050 kPa and shaft power from one or more extraction turbine(s) and/or
back-pressure
turbines, wherein the shaft power drives a device located in a hydrocarbon
processing plant;
(ii) providing a gas mixture stream comprising CO2; (iii) feeding the gas
mixture stream and a
lean-amine stream comprising an amine into an absorption column; (iv)
obtaining a CO2-rich
amine stream and a CO2-depleted residual gas stream from the absorption
column; (v) feeding
at least a portion of the CO2-rich amine stream into a separation column; (vi)
heating the at
least a portion of the CO2-rich amine stream in the separation column using
the exhaust steam
stream to produce an overhead stream rich in CO2 and a bottoms stream rich in
the amine; and
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Date Recue/Date Received 2022-12-09
(vii) recycling at least a portion of the bottoms stream to the absorption
column as at least a
portion of the lean-amine stream.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 schematically illustrates a steam supply/consumption system of
an olefins
production plant including one or more steam cracker furnaces.
[0009] FIG. 2 schematically illustrates an exemplary steam supply/consumption
system
integrating the olefins production plant shown in FIG. 1 and an amine CO2
recovery process.
[0010] FIG. 3 schematically illustrates a steam supply/consumption
configuration of a
comparative olefins production plant including multiple steam crackers.
[0011] FIG. 4 schematically illustrates an inventive steam supply/consumption
configuration
of an olefins production plant modified from the plant of FIG. 3 and steam-
integrated with an
SMR.
DETAILED DESCRIPTION
[0012] Various specific embodiments, versions and examples of the invention
will now be
described, including preferred embodiments and definitions that are adopted
herein for
purposes of understanding the claimed invention. While the following detailed
description
gives specific preferred embodiments, those skilled in the art will appreciate
that these
embodiments are exemplary only, and that the invention may be practiced in
other ways. For
purposes of determining infringement, the scope of the invention will refer to
any one or more
of the appended claims, including their equivalents, and elements or
limitations that are
equivalent to those that are recited. Any reference to the "invention" may
refer to one or more,
but not necessarily all, of the inventions defined by the claims.
[0013] In this disclosure, a process is described as comprising at least one
"step." It should
be understood that each step is an action or operation that may be carried out
once or multiple
times in the process, in a continuous or discontinuous fashion. Unless
specified to the contrary
or the context clearly indicates otherwise, multiple steps in a process may be
conducted
sequentially in the order as they are listed, with or without overlapping with
one or more other
steps, or in any other order, as the case may be. In addition, one or more or
even all steps may
be conducted simultaneously with regard to the same or different batch of
material. For
example, in a continuous process, while a first step in a process is being
conducted with respect
to a raw material just fed into the beginning of the process, a second step
may be carried out
simultaneously with respect to an intermediate material resulting from
treating the raw
materials fed into the process at an earlier time in the first step.
Preferably, the steps are
conducted in the order described.
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[0014] Unless otherwise indicated, all numbers indicating quantities in this
disclosure are to
be understood as being modified by the term "about" in all instances. It
should also be
understood that the precise numerical values used in the specification and
claims constitute
specific embodiments. Efforts have been made to ensure the accuracy of the
data in the
examples. However, it should be understood that any measured data inherently
contains a
certain level of error due to the limitation of the technique and/or equipment
used for acquiring
the measurement.
[0015] Certain embodiments and features are described herein using a set of
numerical upper
limits and a set of numerical lower limits. It should be appreciated that
ranges including the
combination of any two values, e.g., the combination of any lower value with
any upper value,
the combination of any two lower values, and/or the combination of any two
upper values are
contemplated unless otherwise indicated.
[0016] The indefinite article "a" or "an", as used herein, means "at least
one" unless specified
to the contrary or the context clearly indicates otherwise. Thus, embodiments
using "a reactor"
or "a conversion zone" include embodiments where one, two or more reactors or
conversion
zones are used, unless specified to the contrary or the context clearly
indicates that only one
reactor or conversion zone is used.
[0017] The term "hydrocarbon" means (i) any compound consisting of hydrogen
and carbon
atoms or (ii) any mixture of two or more such compounds in (i). The term "Cn
hydrocarbon,"
where n is a positive integer, means (i) any hydrocarbon compound comprising
carbon atom(s)
in its molecule at the total number of n, or (ii) any mixture of two or more
such hydrocarbon
compounds in (i). Thus, a C2 hydrocarbon can be ethane, ethylene, acetylene,
or mixtures of
at least two of these compounds at any proportion. A "Cm to Cn hydrocarbon" or
"Cm-Cn
hydrocarbon," where m and n are positive integers and m < n, means any of Cm,
Cm+1,
.. Cm+2, ..., Cn-1, Cn hydrocarbons, or any mixtures of two or more thereof.
Thus, a "C2 to C3
hydrocarbon" or "C2-C3 hydrocarbon" can be any of ethane, ethylene, acetylene,
propane,
propene, propyne, propadiene, cyclopropane, and any mixtures of two or more
thereof at any
proportion between and among the components. A "saturated C2-C3 hydrocarbon"
can be
ethane, propane, cyclopropane, or any mixture thereof of two or more thereof
at any proportion.
A "Cn+ hydrocarbon" means (i) any hydrocarbon compound comprising carbon
atom(s) in its
molecule at the total number of at least n, or (ii) any mixture of two or more
such hydrocarbon
compounds in (i). A "Cn- hydrocarbon" means (i) any hydrocarbon compound
comprising
carbon atoms in its molecule at the total number of at most n, or (ii) any
mixture of two or more
such hydrocarbon compounds in (i). A "Cm hydrocarbon stream" means a
hydrocarbon stream
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Date Recue/Date Received 2022-12-09
consisting essentially of Cm hydrocarbon(s). A "Cm-Cn hydrocarbon stream"
means a
hydrocarbon stream consisting essentially of Cm-Cn hydrocarbon(s).
[0018] "High-pressure steam" and "HPS" are used interchangeably to mean a
steam having
an absolute pressure of at least 4000 kilopascal ("kPa"). "Super-high-pressure
steam" and
"Super-HPS" are used interchangeably to mean a steam having an absolute
pressure of at least
8,370 kPa. Thus, a Super-HPS is an HPS. "Medium-pressure steam" and "MPS" are
used
interchangeably to mean a steam having an absolute pressure of at least 800
kPa but less than
4,000 kPa. "Low-pressure steam" and "LPS" are used interchangeably to mean a
steam having
an absolute pressure of at least 200 kPa but less than 800 kPa.
[0019] "Consisting essentially of' means comprising? 60 mol%, preferably > 75
mol%,
preferably? 80 mol%, preferably > 90 mol%, preferably > 95 mol%; preferably 98
mol%, of
a given material or compound, in a stream or mixture, based on the total moles
of molecules in
the stream or mixture.
[0020] A "back-pressure steam turbine" means a steam turbine receiving a steam
feed and
producing no steam stream having an absolute pressure below 100 kPa and
supplied to a surface
condenser. Depending on the pressure of the steam feed and its configuration,
a back-pressure
steam turbine may produce one or more exhaust streams, e.g., an HPS stream, an
MPS stream,
and LPS stream, and combinations thereof.
[0021] An "extraction steam turbine" means a steam turbine receiving a steam
feed and
producing at least two exhaust steam streams having differing pressures.
Depending on the
pressure of the steam feed and its configuration, an extraction steam turbine
may produce two
or more steam streams including one or more of, e.g., an HPS stream, an MPS
stream, an LPS
stream, and an condensable stream having an absolute pressure below 100 kPa
supplied to a
surface condenser.
[0022] For the purposes of this disclosure, the nomenclature of elements is
pursuant to the
version of the Periodic Table of Elements (under the new notation) as provided
in Hawley's
Condensed Chemical Dictionary, 16th Ed., John Wiley & Sons, Inc., (2016),
Appendix V.
I. Integration of Amine CO2 Separation with a Hydrocarbon Production Plant
[0023] A first aspect of this disclosure relates to a process comprising: (i)
obtaining an
exhaust steam stream having an absolute pressure from 200 kPa to 1,050 kPa and
shaft power
from one or more extraction turbine(s) and/or back-pressure turbine(s),
wherein the one or more
extraction turbine(s) and/or back-pressure turbine(s) drive a device located
in a hydrocarbon
processing plant; (ii) providing a gas mixture stream comprising CO2; (iii)
feeding the gas
mixture stream and a lean-amine stream comprising an amine into an absorption
column; (iv)
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Date Recue/Date Received 2022-12-09
obtaining a CO2-rich amine stream and a CO2-depleted residual gas stream from
the absorption
column; (v) feeding at least a portion of the CO2-rich amine stream into a
separation column;
(vi) heating the at least a portion of the CO2-rich amine stream in the
separation column using
the exhaust steam stream to produce an overhead stream rich in CO2 and a
bottoms stream rich
in the amine; and (vii) recycling at least a portion of the bottoms stream to
the absorption
column as at least a portion of the lean-amine stream.
[0024] The extraction turbine(s) and/or back-pressure turbine(s) in step (i)
are present in a
hydrocarbon processing plant, e.g., an oil refinery, an olefins production
plant, a biofuel
production plant, and the like. These plants typically include equipment
consuming shaft
power produced by steam turbines, e.g., gas compressors at various power
ratings, pumps,
electricity generators, and the like. In an olefins production plant including
one or more steam
crackers, a steam cracking feed (e.g., ethane, propane, butanes, naphthas, gas
oils, resids, crude
oil, and mixtures thereof) is fed into the convection section of the steam
cracker and preheated
therein, and then transferred to the radiant section of the steam cracker,
where it is subjected to
high temperature and a short residence time, thereby producing a steam cracker
effluent exiting
the steam cracker comprising H2, C1-C4 hydrocarbons including the desired C2-
C4 olefins,
and C5+ hydrocarbons. The steam cracker effluent is then immediately cooled
down by
quenching and/or indirect heat exchange to produce a cooled mixture, from
which a process
gas stream comprising H2 and C 1-C4 hydrocarbons including the desirable C2-C4
olefins is
separated. The process gas stream is then typically compressed, using multiple
compressor
stages typically driven by a steam turbine(s), and then cooled down to a very
low temperature
in a chill train, where desirable products such as ethylene, propylene,
butenes, and the like, can
be recovered via cryogenic distillation. In addition, steam turbines are
routinely used to drive
one or more of the propylene refrigeration compressor and the ethylene
refrigeration
compressor included in the chill train. As discussed above, to maximize shaft
power production,
historically these steam turbines located in hydrocarbon processing plants
(especially olefins
production plants) are routinely configured to produce an exhaust steam stream
having a very
low pressure, e.g., < 100 kPa, < 80 kPa, < 50 kPa, which is then supplied to
and condensed at
surface condensers with large duty ratings. Such condensing can result in
release of significant
amount of thermal energy into the atmosphere. In addition, surface condensers
having large
duty ratings are expensive to buy and operate. Therefore, it would be highly
desirable to reduce
the size of the surface condensers or eliminate at least some, preferably all,
of them without
causing problems to the operation of the devices driven by the steam turbines.
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[0025] We have found that the extraction turbine(s) and/or back-pressure
turbines in step
(i) of the processes of this disclosure can include advantageously any steam
turbines in the
hydrocarbon processing plant such as an olefins production plant receiving a
steam feed having
a pressure higher than the exhaust steam stream. Thus, the extraction
turbine(s) and/or back-
.. pressure turbine(s) may independently receive an HPS feed such as a Super-
HPS feed, or an
MPS feed, desirably superheated. Depending on the pressure of the steam feed
thereto, the
extraction turbine(s) may produce, in addition to the exhaust steam stream
having an absolute
pressure from 200 kPa to 1,050 kPa, one or more of: (i) an HPS stream; (ii) an
MPS stream;
and (iii) a condensable stream supplied to a surface condenser. Preferably, if
the extraction
turbine(s) produce (iii) a condensable stream, the condensable stream has a
quantity requiring
a reduced-size surface condenser, e.g., a surface condenser having a rating of
< 80 MW, < 60
MW, < 50 MW, < 40 MW, < 20 MW, < 10 MW, or even < 1 MW. Depending on the
pressure
of the steam feed thereto, the back-pressure turbine(s) may produce, in
addition to the exhaust
steam stream having an absolute pressure from 200 kPa to 1,050 kPa, one or
more of: (i) an
HPS stream; or (ii) an MPS stream. Preferably at least one, preferably all, of
the extraction
turbine and/or back-pressure turbine(s) do not produce (iii) a condensable
stream (e.g., a steam
stream having an absolute pressure < 100 kPa) supplied to a surface condenser.
In the case of
an olefins production plant, the extraction turbine(s) and/or the back-
pressure turbine(s) can
include one or more of: the steam turbines driving the process gas
compressors; the steam
turbine(s) driving the propylene refrigeration compressor(s); the steam
turbine(s) driving the
ethylene refrigeration compressor(s); the steam turbine(s) driving various air
compressors; the
steam turbine(s) driving various pumps; and the steam turbine(s) driving
electricity
generator(s), and combinations thereof.
[0026] The pressure of the exhaust steam stream having an absolute
pressure from 200 kPa
to 1,050 kPa may be produced by a single extraction turbine or back-pressure
turbine.
Alternatively, the exhaust steam stream can be a joint stream of several such
exhaust steam
streams having similar pressures produced from multiple extraction turbine(s)
and/or back-
pressure turbine(s). This pressure range is particularly advantageous for
supplying heat needed
in the regeneration step of an amine CO2 separation process. Thus, the exhaust
steam stream
can have an absolute pressure from, e.g., 200 kPa, 250 kPa, 300 kPa, 350 kPa,
400 kPa, 450
kPa, 500 kPa, to 550 kPa, 600 kPa, 650 kPa, 700 kPa, 750 kPa, 800 kPa, to 850
kPa, 900 kPa,
950 kPa, 1,000 kPa, or even 1,050 kPa. Preferably, the exhaust steam stream
has an absolute
pressure of no greater than 480 kPa.
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Date Recue/Date Received 2022-12-09
[0027] The gas mixture comprising CO2 can comprise CO2 at various molar
concentration
from, e.g., 1%, 2%, 4%, 5%, 6%, 8%, 10%, to 15%, 20%, 25%, 30%, to 35%, 40%,
50%, to
55%, 60%, 65%, 70%, 75%, to 80%, 85%, or even 90%, based on the total moles of
molecules
in the gas mixture. Preferably, the gas mixture comprises CO2 at a molar
concentration from
5% to 25%, based on the total moles of molecules in the gas mixture.
[0028] Non-limiting examples of the gas mixture comprising CO2 include
flue gases
produced from combusting: (i) a fuel comprising coal; (ii) a fuel gas
comprising a hydrocarbon
such as natural gas; (iii) a fuel oil comprising a hydrocarbon such as diesel,
kerosene, and the
like; or (iv) a fuel gas comprising CO. Additional non-limiting examples of
the gas mixture
comprising CO2 include exhaust gases and/or intermediate gas streams produced
in industrial
processes such as: (i) cement production; (ii) steel production; (iii) olefins
production; (iv)
electricity generation; (v) syngas production; and (v) hydrogen production.
The gas mixture
may be produced from a furnace combusting a fuel as described above. The gas
mixture may
be produced from a chemical reactor.
[0029] In preferred embodiments of the process of this disclosure, the gas
mixture stream
in step (ii) of the processes of this disclosure is produced by a syngas
producing process in a
syngas producing unit described in Section II below. For example, the gas
mixture stream may
be a stream of the first syngas, the second syngas, or the third syngas
described in Section II
below. In yet another preferred embodiment, the gas mixture stream in step
(ii) of the processes
of this disclosure is produced by the Hz-rich fuel gas producing process
described in Section
III below. For example, the gas mixture stream may be the crude gas mixture
stream comprising
CO2, H2, and optionally a hydrocarbon such as CH4 in the Hz-rich fuel gas
producing process
described in Section III below. Thus, the gas mixture stream may comprise,
consist essentially
of, or consist of H2 and CO2. The gas mixture stream may comprise, consist
essentially of, or
consist of H2, CO, and CO2. The gas mixture stream may comprise, consist
essentially of, or
consist of Hz, CO2, and H20. The gas mixture stream may comprise, consist
essentially of, or
consist of Hz, CO, CO2, and CH4. The gas mixture stream may comprise, consist
essentially of,
or consists of H2, CO, CO2, CH4, and H20.
[0030] In step (iii), the gas mixture stream and a lean-amine stream
comprising an amine
.. are fed into an absorption column. Any amine absorption column and amine
known to one
skilled in the art of CO2 separation may be used. Non-limiting examples of
useful amine
include: monoethanolamine ("MEA"), di ethanolamine ("DEA"),
methyldiethanolamine
("MDEA"), diisopropanolamine ("DIPA"), diglycolamine ("DGA"), and mixtures
thereof.
The most commonly used amines for CO2 separation and capture are DEA, MEA, and
MDEA.
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Date Recue/Date Received 2022-12-09
In a preferred embodiment, the lean-amine stream is supplied to the upper
section of the
absorption column, and the gas mixture is fed into a lower section of the
absorption column.
Counter-current contacting between the gas mixture and the amine in the
absorption column
results in producing a CO2-rich amine stream and a CO2-depelted residual gas
stream in step
(iv). Preferably the CO2-rich amine stream exits the absorption column from
the bottom and
the CO2-depleted residual gas stream from the top.
[0031] In step (v), at least a portion of the CO2-rich amine stream is
fed into a separation
column. Any design of the separation column known to one skilled in the art
may be used. The
separation column is sometimes also called a regeneration column in that the
amine is
regenerated from this column. In step (vi), at least a portion of the CO2-rich
amine stream is
heated in the separation column. Such heating can be effected by using a heat
exchanger. At
least a part, preferably? 30%, preferably 2 50%, preferably 60%, preferably
80%, preferably
> 90%, preferably the entirety, of the thermal energy used for the heating is
provided by the
exhaust steam stream produced in step (i). Upon being heated to a desirable
temperature, the
CO2 separates from the amine in the separation column, resulting in a CO2-rich
stream and a
stream rich in the amine. Preferably, the CO2-rich stream exits the separation
column at the
top, and the stream rich in the amine from the bottom. The stream rich in
amine can be at least
partly recycled to the absorption column as at least a portion of the lean-
amine stream in step
(vii). The CO2-rich stream can be compressed, liquefied, conducted away,
stored, sequestered,
or utilized in any suitable applications known to one skilled in the art. In
one embodiment, the
CO2¨rich stream, upon optional compression, can be conducted away in a CO2
pipeline. In
another embodiment, the CO2¨rich stream, upon optional compression and/or
liquefaction, can
be injected and stored in a geological formation. In yet another embodiment,
the CO2¨rich
stream, upon optional compression and/or liquefaction, can be used in
extracting hydrocarbons
present in a geological formation. Another exemplary use of the CO2¨rich
stream is in food
applications.
[0032] The exhaust steam stream produced from the extraction turbine(s)
and/or back-
pressure turbine(s) having an absolute pressure from 200 kPa to 1,050 kPa
(preferably no
greater than 800 kPa, preferably no greater than 700 kPa, preferably no
greater than 600 kPa,
preferably no greater than 500 kPa, preferably no greater than 480 kPa,
preferably no greater
than 380 kPa) is particularly suitable for supplying heat to the separation
column to effect the
separation of CO2 from the amine. One skilled in the art can extract the
suitable quantity of the
exhaust steam stream from the one or more extraction turbine(s) and/or back-
pressure
turbine(s), as illustrated below in this disclosure, to satisfy the heating
duty needed in the
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Date Recue/Date Received 2022-12-09
CO2/amine separation/regeneration column to effect the separation of any given
quantity of the
gas mixture with any CO2 concentration therein. By producing the exhaust steam
stream and
supplying the same to the separation column, residual thermal energy in the
exhaust steam
stream is utilized to perform useful work. This is in contrast to the prior
art of producing a
condensable steam stream further condensed in a surface condenser, where
residual thermal
energy in the condensable stream is released to the atmosphere and lost. When
a hydrocarbon
processing plant such as an olefins production plant including multiple large
steam turbines is
steam-integrated with an amine CO2-separation process according to the various
embodiments
of this disclosure, substantial improvement in energy efficiency can be
achieved, as
demonstrated by the Examples in this disclosure below. Moreover, extraction of
such exhaust
steam stream(s) can be carried out in one or more extraction turbine(s) and/or
back-pressure
turbine(s), such that each turbine can still produce sufficient amount of
shaft power for driving
the target equipment. In certain embodiments, it may be desirable to increase
steam feed to one
or more of the extraction turbine(s) and/or the back-pressure turbine(s) to
ensure the production
of both sufficient amount of shaft power and the exhaust steam stream. To that
end, in certain
specific embodiments, one may replace an existing steam turbine with an
electric motor, so
that the steam required that the replaced steam turbine can be supplied to an
extraction turbine
and/or a back-pressure turbine producing the exhaust steam stream and the
shaft power in
sufficient amount. In certain embodiments, the exhaust steam stream provides a
quantity of
.. energy to the at least a portion of the CO2-rich amine stream in step (vi);
and at least 30%
(preferably? 50%, preferably > 60%, preferably ? 70%) of the quantity of
energy would have
been lost to the atmosphere in a comparative process identical with the
process except the
extraction turbine or back-pressure turbine is substituted by an
extraction/condensing turbine
with the identical power rating.
II. The Syngas Production Process and the Syngas Producing Unit
[0033] In certain preferred embodiments, the gas mixture in step (ii) of
the processes of this
disclosure is produced by a syngas production process generally comprising the
following
steps: (A) supplying a hydrocarbon feed and a steam feed into a syngas
producing unit
comprising a reforming reactor under syngas producing conditions to produce a
reformed
stream exiting the reforming reactor, wherein the syngas producing conditions
include the
presence of a reforming catalyst, and the reformed stream comprises H2, CO,
and steam; (B)
cooling the reformed stream by using a waste heat boiler ("WHB") to produce a
cooled
reformed stream and to generate a high-pressure steam ("HPS") stream; (C)
heating the HPS
stream to obtain a super-heated high-pressure steam ("SH-HPS") stream, wherein
the SH-HPS
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Date Recue/Date Received 2022-12-09
stream has a pressure higher than the steam feed supplied to the syngas
producing unit in step
(A); (D) expanding at least a portion of the SH-HPS stream in at least one
stage of a steam
turbine to produce shaft power and an expanded steam stream having a pressure
equal to or
higher than the steam feed; and (E) supplying at least a portion of the
expanded steam stream
as the steam feed in step (A). The SH-HPS stream produced in step (C) may be
supplied to an
extraction turbine and/or a back-pressure turbine of step (i) of the process
of this disclosure
directly. Alternatively and additionally, a steam turbine may receive the SH-
HPS produced in
step (C) and produce an HPS or MPS stream, which can be supplied to an
extraction turbine
and/or a back-pressure turbine in step (i) of the process of this disclosure.
[0034] Step (A) of this process includes supplying a hydrocarbon feed and a
steam feed into
a syngas producing unit comprising a reforming reactor under syngas producing
conditions to
produce a reformed stream exiting the reforming reactor, wherein the syngas
producing
conditions include the presence of a reforming catalyst, and the reformed
stream comprises H2,
CO, and steam. The hydrocarbon feed can consist essentially of Cl-C4
hydrocarbons
(preferably saturated), preferably consists essentially of Cl-C3 hydrocarbons
(preferably
saturated), preferably consists essentially of C1-C2 hydrocarbons (preferably
saturated), and
preferably consists essentially of CH4. The hydrocarbon feed and the steam
feed may be
combined to form a joint stream before being fed into the syngas producing
unit. Alternatively,
they may be fed into the syngas producing unit as separate streams, in which
they admix with
each other to form a mixture. The feed stream(s) can be pre-heated by, e.g., a
furnace, a heat
exchanger, and the like, before being fed into the syngas producing unit. The
syngas producing
unit can comprise a pre-reformer first receiving the feed stream(s),
especially if the
hydrocarbon feed comprises significant amount of C2+ hydrocarbons. In a pre-
reformer, the
hydrocarbon feed/steam feed mixture contacts a pre-reforming catalyst under
conditions such
that the C2+ hydrocarbons are preferentially converted into CH4. The inclusion
of a pre-
reformer can reduce coking and fouling of the down-stream reforming reactor.
The
hydrocarbon feed may have a temperature from, e.g., 15 C, 20 C, 30 C, 40
C, to 50 C, 60
C, 70 C, 80 C, 90 C, to 95 C, 100 C, 110 C, 120 C, 130 C, 140 C, ,or
even 150 C,
and an absolute pressure from e.g., 1,300 kPa, 1,400 kPa, 1,500 kPa, 1,600
kPa, 1,700 kPa,
1,800 kPa, 1,900 kPa, 2,000 kPa, to 2,100 kPa, 2,200 kPa, 2,300 kPa, 2,400
kPa, 2,500 kPa,
2,600 kPa, 2,700 kPa, 2,800 kPa, 2,900 kPa, 3,000 kPa, to 3,000 kPa, 3,200
kPa, 3,400 kPa,
3,500 kPa, 3,600 kPa, 3,800 kPa, 4,000 kPa, to 4,200 kPa, 4,400 kPa, 4,500
kPa, 4,600 kPa,
4,800 kPa, or even 5,000 kPa. The steam feed may have a temperature from,
e.g., 250 C, 260
C, 270 C, 280 C, 290 C, 300 C, to 310 C, 320 C, 330 C, 340 C, 350 C,
360 C, 370
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Date Recue/Date Received 2022-12-09
C, 380 C, 390 C, to 400 C, 410 C, 420 C, 430 C, 440 C, or even 450 C,
and an
absolute pressure from e.g., 1,300 kPa, 1,400 kPa, 1,500 kPa, 1,600 kPa, 1,700
kPa, 1,800 kPa,
1,900 kPa, 2,000 kPa, to 2,100 kPa, 2,200 kPa, 2,300 kPa, 2,400 kPa, 2,500
kPa, 2,600 kPa,
2,700 kPa, 2,800 kPa, 2,900 kPa, 3,000 kPa, to 3,000 kPa, 3,200 kPa, 3,400
kPa, 3,500 kPa,
3,600 kPa, 3,800 kPa, 4,000 kPa, to 4,200 kPa, 4,400 kPa, 4,500 kPa, 4,600
kPa, 4,800 kPa, or
even 5,000 kPa. Preferably, the steam feed is a superheated steam.
10035] The effluent from the pre-reformer can be then fed into the
reforming reactor
operated under syngas producing conditions, wherein the forward reaction of
the following is
favored and desirably occurs in the presence of the reforming catalyst:
Reforming Catalyst
CH4 +H20 H20 . CO + 3 H2
(R-1)
[0036] The syngas producing condition can include a temperature of, e.g.,
from 750 C, 760
C, 780 C, 800 C, 850 C, 900 C, to 950 C, 1,000 C, 1,050 C, 1,100 C, to
1150 C, or
even 1200 C, and an absolute pressure of, e.g., from 700 kPa, 800 kPa, 900
kPa, 1,000 kPa,
to 1,500 kPa, 2,000 kPa, 2,500 kPa, 3,000 kPa, to 3,500 kPa, 4,000 kPa, 4,500
kPa, or even
5,000 kPa, in the reforming reactor, depending on the type of the reforming
reactor and the
syngas producing conditions. A lower pressure in the reformed stream, and
hence a lower
pressure in the reforming reactor, is conducive to a higher conversion of CH4
in reforming
reactor and hence a lower residual CH4 concentration in the reformed stream.
The reformed
stream exiting the reforming reactor therefore comprises CO, Hz, residual CH4
and H20, and
optionally CO2 at various concentrations depending on, among others, the type
of the reforming
reactor and the syngas producing conditions. The reformed stream can have a
temperature of,
e.g., from 750 C, 760 C, 780 C, 800 C, 850 C, 900 C, to 950 C, 1,000
C, 1,050 C,
1,100 C, to 1150 C, or even 1200 C, and an absolute pressure of, e.g., from
700 kPa, 800
kPa, 900 kPa, 1,000 kPa, to 1,500 kPa, 2,000 kPa, 2,500 kPa, 3,000 kPa, to
3,500 kPa, 4,000
kPa, 4,500 kPa, or even 5,000 kPa, depending on the type of the reforming
reactor and the
syngas producing conditions.
[0037] A preferred type of the reforming reactor in the syngas producing
unit is an SMR.
An SMR typically comprises one or more heated reforming tubes containing the
reforming
catalyst inside. The hydrocarbon/steam feed stream enters the tubes, heated to
a desired
elevated temperature, and passes through the reforming catalyst to effect the
desirable
reforming reaction mentioned above. While an SMR can have many different
designs, a
preferred SMR comprises a furnace enclosure, an upper convection section, a
lower radiant
section, and one or more burners located in the radiant section combusting a
fuel to produce a
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Date Recue/Date Received 2022-12-09
hot flue gas and supply thermal energy to heat the radiant section and the
convection section.
The hydrocarbon/steam feed stream enters the reforming tube at a location in
the convection
section, winds downwards through the convection section, whereby it is pre-
heated by the
ascending hot flue gas produced from fuel combustion at the burner(s), and
then enters the
radiant section proximate the burners combustion flames, whereby it contacts
the reforming
catalyst loaded in the reforming tube(s) in the radiant section, to produce a
reformed stream
exiting the SMR from a location in the radiant section. The syngas producing
conditions in the
reforming tube(s) in the radiant section can include a temperature of, e.g.,
from 750 C, 760
C, 780 C, 800 C, to 820 C, 840 C, 850 C, to 860 C, 880 C, or even 900
C, and an
.. absolute pressure of, e.g., from 700 kPa, 800 kPa, 800 kPa, 900 kPa, 1,000
kPa, to 1,500 kPa,
2,000 kPa, 2,500 kPa, 3,000 kPa, or even 3,500 kPa. To achieve a high CH4
conversion in the
SMR, and a low CH4 concentration in the Hz-rich stream produced from the
process, the syngas
producing conditions in the SMR preferably includes an absolute pressure of <
2,169 kPa (300
psig), more preferably < 1,825 kPa (250 psig). Description of an SMR can be
found in, e.g.,
The International Energy Agency Greenhouse Gas R&D Program ("IEAGHG"), "Techno-
Economic Evaluation of SMR Based Standalone (Merchant) Plant with CCS",
2017/02,
February 2017, the content of which is incorporated herein in its entirety.
[0038] The reforming reactor in the syngas producing unit may comprise an
autothermal
reformer ("ATR"). An ATR typically receives the hydrocarbon/steam feed(s) and
an 02 stream
into a reaction vessel, where a portion of the hydrocarbon combusts to produce
thermal energy,
whereby the mixture is heated to an elevated temperature and then allowed to
contact a bed of
reforming catalyst to effect the desirable reforming reaction and produce a
reformed stream
exiting the vessel. An ATR can be operated at a higher temperature and
pressure than an SMR.
The syngas producing conditions in the ATR and the reformed stream exiting an
ATR can have
a temperature of, e.g., from 800 C, 850 C, 900 C, to 950 C, 1,000 C, 1050
C, to 1,100 C,
1,150 C, or even 1,200 C, and an absolute pressure of, e.g., from 800 kPa,
900 kPa, 1,000
kPa, to 1,500 kPa, 2,000 kPa, 2,500 kPa, 3,000 kPa, to 3,500 kPa, 4,000 kPa,
4,500 kPa, or
even 5,000 kPa. Commercially available ATRs, such as the SyncorTm ATR
available from
Haldor Topso, having an address at Haldor Topsoes Alle 1, DK-2800, Kgs.
Lyngby, Denmark,
may be used in the process of this disclosure.
[0039] The syngas producing unit used in step (A) of the process of this
disclosure can
include one or more SMR only, one or more ATR only, or a combination of one or
more of
both.
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Date Recue/Date Received 2022-12-09
[0040] The reformed stream exiting the reforming reactor has a high
temperature and high
pressure as indicated above. It is highly desirable to capture the heat energy
contained therein.
Thus, in step (B), the reformed stream passes through a waste heat recovery
unit ("WHRU")
to produce a cooled reformed stream and to generate a high-pressure steam
("HPS") stream.
The cooled reformed stream can have a temperature from, e.g., 285 C, 290 C,
300 C, to 310
C, 320 C, 330 C, 340 C, 350 C, to 360 C, 370 C, 380 C, 390 C, or even
400 C. The
cooled reformed stream can have a pressure substantially the same as the
reformed stream
exiting the reforming reactor. The WHRU can include, e.g., one or more heat
exchanger and
one or more steam drum in fluid communication with the heat exchanger. The
steam drum
supplies a water stream to the heat exchanger, where it is heated and can be
then returned to
the steam drum, where steam is separated from liquid phase water. The HPS
stream can have
an absolute pressure from, e.g., 4,000 kPa, 5,000 kPa, 6,000 kPa, 7,000 kPa,
8,000 kPa, to
9,000 kPa, 10,000 kPa, 11,000 kPa, 12,000 kPa, 13,000 kPa, or even 14,000 kPa.
In certain
embodiments, the HPS stream is preferably a Super-HPS stream. The thus
produced HPS
stream is a saturated steam stream.
[0041] To make the HPS stream more useful, it may be further heated in
step (C) to produce
a superheated HPS ("SH-HPS") stream in, e.g., a furnace. In case the syngas
producing unit
comprises an SMR having a convection section as described above, the saturated
HPS stream
may be advantageously superheated in the convection section of the SMR and/or
in an auxiliary
furnace. In case the syngas producing unit comprises one or more ATR but no
SMR, the
saturated HPS stream can be superheated in an auxiliary furnace. The auxiliary
furnace can
include one or more burners combusting a fuel gas stream to supply the needed
thermal energy
as is known to one skilled in the art. The SH-HPS stream can have one or both
of: (i) a
temperature from, e.g., 350 C, 360 C, 370 C, 380 C, 390 C, 400 C, to 410
C, 420 C,
430 C, 440 C, 450 C, to 460 C, 470 C, 480 C, 490 C, 500 C, to 510 C,
520 C, 530
C, 540 C, or even 550 C; and (ii) an absolute pressure from, e.g., e.g.,
4,000 kPa, 5,000 kPa,
6,000 kPa, 7,000 kPa, 8,000 kPa, to 9,000 kPa, 10,000 kPa, 11,000 kPa, 12,000
kPa, 13,000
kPa, or even 14,000 kPa. Preferably the SH-HPS stream has a temperature of at
least 371 C
and the steam feed in step (A) has an absolute pressure of at least 1700 kPa.
The SH-HPS
stream has a pressure higher than that of the steam feed supplied to the
syngas producing unit
in step (A), so that the SH-HPS can be expanded to produce a steam stream
having a pressure
in the vicinity of the pressure of the steam feed, which can then be supplied
to the syngas
producing unit as at least a portion of the steam feed. Preferably the SH-HPS
stream has a
temperature of at least 482 C and an absolute pressure of at least 10,000
kPa, and the steam
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Date Recue/Date Received 2022-12-09
feed has an absolute pressure of at least 1,700 kPa (e.g., at least 2,500
kPa). In a preferred
embodiment, the SH-HPS stream may be supplied to an HPS header located in an
industrial
plant, such as an olefins production plant, supplying HPS to suitable
equipment consuming
SH-HPS. In another embodiment, the SH-HPS stream may be also a Super-HPS
stream, and
.. supplied to a Super-HPS header located in an industrial plant, such as an
olefins production
plant, supplying Super-HPS to suitable equipment consuming superheated Super-
HPS.
[0042] In step (D), at least a portion of the SH-HPS stream is expanded
in at least one stage
of a steam turbine to produce shaft power and an expanded steam stream having
a pressure
equal to or higher than that of the steam feed to the syngas producing unit.
The expanded steam
stream may have a temperature from, e.g., 260 C, 270 C, 280 C, 290 C, 300
C, to 310 C,
320 C, 330 C, 340 C, 350 C, to 360 C, 370 C, 380 C, 390 C, 400 C, or
even 405 C.
The expanded steam stream has a pressure lower than the SH-HPS stream, which
may range
from, e.g., 1,380 kPa, 1,400 kPa, 1,500 kPa, 1,600 kPa, 1,700 kPa, 1,800 kPa,
1,900 kPa, 2,000
kPa, to 2,200 kPa, 2,400 kPa, 2,500 kPa, 2,600 kPa, 2,800 kPa, 3,000 kPa, to
3,200 kPa, 3,400
kPa, 3,500 kPa, 3,600 kPa, 3,800 kPa, 4,000 kPa, to 4,200 kPa, 4,400 kPa, or
even 4,500 kPa.
The expanded steam stream may be an HPS stream, or an MPS stream. The steam
turbine may
produce multiple exhaust streams in certain embodiments, e.g., an HPS stream
and an LPS
stream; an HPS stream and a condensable stream supplied to a condenser; an MPS
stream and
an LPS stream; or an MPS stream and a condensable stream supplied to a
condenser.
[0043] Step (D) can advantageously include steam integration between a
syngas producing
unit and an olefins production plant including a steam cracker receiving a
hydrocarbon feed
and steam operated under steam cracking conditions to produce a steam cracker
effluent exiting
the steam cracker. The high-temperature steam cracker effluent is immediately
cooled by
quenching and/or an indirect heat exchanger, where a significant amount of
steam may be
.. generated, which can be subsequently superheated in the convection section
of the steam
cracker. The cooled steam cracker effluent can be then separated to produce,
among others, a
process gas stream comprising methane, ethane, C2-C4 olefins and dienes. To
recover the
olefins products from the process gas stream, it is typically first compressed
to an elevated
pressure, cooled in a chill train under cryogenic conditions, and then
separated in distillation
columns such as a demethanizer, a deethanizer, a depropanizer, a C2 splitter,
a C3 splitter, and
the like. To that end, at least three (3) large compressors: a process-gas
compressor, a propylene
refrigeration compressor and an ethylene refrigeration compressor may be used.
In a modern,
world scale olefins plant, the combined shaft power of these compressors can
exceed 100 MW
(134,000 hp). This very high shaft power demand is a characteristic of olefins
production
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Date Recue/Date Received 2022-12-09
plants, and differentiates them from most other petrochemical facilities.
Typically the large
compressors are driven by steam-turbines. The majority of the steam can be
generated by the
steam produced from cooling the steam cracker effluent as described above. If
necessary,
boilers are used to make-up the required steam volumes.
[0044] Because of the large shaft power requirements of the major
compressors, for
efficient olefin production it is important that the steam-power cycle be as
efficient as possible.
A multi-pressure-level steam system with the highest steam pressure level
being nominally 100
BarG (1500 psig, or 10.3 MPaG) or higher may be advantageously used. This
Super-HPS may
be superheated in order to maximize the specific power output (kW power/kg
steam consumed)
of the turbines. In addition to the large compressor steam turbines, smaller
turbine drivers may
be used for several services within the olefins production plant (e.g.:
cooling water pumps,
quench water pumps, boiler-feed water pumps, air compressors, etc.). These
turbines can
receive HPS, MPS, or LPS streams. In addition, process heating duties existing
in the olefins
recovery train may be satisfied by condensing one or more HPS, MPS, or LPS
stream(s).
[0045] In certain embodiments, a single stage of steam turbine is used in
step (D). In certain
other embodiments, multiple cascading stages of steam turbines may be used,
where an
expanded steam stream produced from an upstream stage, preferably an HPS
stream or an MPS
stream, is supplied to a downstream steam turbine, expanded therein to produce
a lower
pressure steam stream and additional shaft power. The shaft power produced by
the one or
more steam turbines in step (D) can be used to perform mechanical work such
as: driving a
generator to produce electrical power transmissible to local and/or distant
electrical equipment;
driving a compressor or pump located in an industrial plant, such as a process
gas compressor,
a propylene refrigeration compressor, an ethylene refrigeration compressor, an
air compressor,
and/or various pumps located in an olefins production plant. The expanded
steam stream may
be supplied to a steam header with the suitable pressure rating located in any
industrial plant
such as an olefins production plant. In certain embodiments, the SH-HPS stream
obtained in
step (C) may be supplied to an olefins production plant at a pressure no less
than the maximal
pressure required for the operation of any steam turbine having a power rating
of at least 1
megawatt (1 MW, or? 5 MW, or? 10 MW, or > 20 MW) in the olefins production
plant. In
certain preferred embodiments, the SH-HPS stream obtained from step (C) (which
may or not
be a Super-HPS stream) may be supplied to a first stage steam turbine that
drives a process gas
compressor in an olefins production plant, and the expanded steam stream from
the first stage
steam turbine, which may be an SH-HPS stream or an MPS stream, may be supplied
to a second
stage steam turbine producing a second expanded steam stream and shaft power
driving another
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Date Recue/Date Received 2022-12-09
process gas compressor, a propylene refrigeration compressor, an ethylene
refrigeration
compressor, an air compressor, and/or a pump in the olefins production plant.
In another
embodiment, the SH-HPS stream obtained from step (C) may be supplied to drive
one or more
process gas compressors, a propylene refrigeration compressor, and an ethylene
refrigeration
compressor, each producing an expanded steam stream having the same, similar,
or different
pressure. The expanded steam streams from the first stage and/or the second
stage can then be
used to provide process heat, or supplied to additional steam turbines,
depending on their
respective pressures. In addition, one or more of the steam turbines may
exhaust a condensable
steam stream fed to a condenser to produce a condensate water stream.
[0046] While the shaft power produced in step (D) may be used to drive an
electricity
generator in a power island, in preferred embodiments of this disclosure where
the shaft power
is used to drive compressors, pumps, and the like in an integrated olefins
production plant, such
power island can be eliminated or included at a smaller size, resulting in
considerable reduction
in capital and operational costs.
[0047] The cooled reformed stream obtained in step (B) of the reforming
process as
described above comprises H2, CO, and steam. It can be used for producing
syngas. By abating
steam from the cooled reformed gas, one can obtain a first syngas comprising
CO and H2.
Alternatively, one can further subject the cooled reformed stream in one or
more stages of shift
reactor to convert a portion of the CO and steam into CO2 and H2, followed by
steam abatement
to obtain a second syngas comprising CO, H2, and CO2. One may further recover
the CO2 from
the second syngas to produce a third syngas consisting essentially of CO, H2,
and optional
residual hydrocarbon, with various CO concentration. The first, second, and
third syngases
may be used for various applications, e.g., industrial heating, ammonia
production, and the
like. In a preferred embodiment, the third syngas may comprise CO at a very
low concentration
of, e.g., < 10 mol%, < 8 mol%, < 5 mol%, < 3 mol%, < 1 mol%, < 0.5 mol%, < 0.1
mol%,
based on the total moles of molecules in the third syngas, in which case the
third syngas is an
Hz-rich gas. Such Hz-rich gas can be advantageously used as a fuel gas, the
combustion of
which can produce a flue gas having low CO2 emission.
III. The Process for Producing a Hz-Rich Fuel Gas
[0048] A particularly advantageous process for producing Hz-rich fuel gas
comprises: (I)
supplying a hydrocarbon feed and a steam feed into a syngas producing unit
comprising a
reforming reactor under syngas producing conditions to produce a reformed
stream exiting the
reforming reactor, wherein the syngas producing conditions include the
presence of a reforming
catalyst, and the reformed stream comprises H2, CO, and steam; (II) cooling
the reformed
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Date Recue/Date Received 2022-12-09
stream by using a waste heat recovery unit ("WHRU") to produce a cooled
reformed stream
and to generate a high-pressure steam ("HPS") stream; (III) contacting the
cooled reformed
stream with a first shifting catalyst in a first shift reactor under a first
set of shifting conditions
to produce a first shifted stream exiting the first shift reactor, wherein the
first shifted stream
has a lower CO concentration and a higher CO2 concentration than the cooled
reformed stream;
(IV) cooling the first shifted stream to obtain a cooled first shifted stream;
(V) contacting the
cooled first shifted stream with a second shifting catalyst in a second shift
reactor under a
second set of shifting conditions to produce a second shifted stream exiting
the second shift
reactor, wherein the second shifted stream has a lower CO concentration and a
higher CO2
concentration than the cooled first shifted stream; (VI) abating steam present
in the second
shifted stream to produce a crude gas mixture stream comprising CO2 and Hz;
(VII) recovering
at least a portion of the CO2 present in the crude gas mixture stream to
produce a CO2 stream
and a Hz-rich stream, wherein the Hz-rich stream comprises H2 at a
concentration of at least 80
mol%, based on the total moles of molecules in the Hz-rich stream; and (VIII)
combusting a
portion of the Hz-rich stream in the presence of an oxidant to generate
thermal energy and to
produce a flue gas stream.
[0049] Steps (I) and (II) may be identical with steps (A) and (B) of the
syngas producing
process described above in Section II above.
[0050] In step (III) of the process, the cooled reformed stream contacts
a first shifting
catalyst in a first shift reactor under a first set of shifting conditions to
produce a first shifted
stream exiting the first shift reactor. The first set of shifting conditions
includes the presence
of a first shift catalyst. Any suitable shift catalyst known to one skilled in
the art may be used.
The forward reaction of the following preferentially occur in the first shift
reactor:
First Shift Catalyst
CO + H20 ¨ CO2 + H2
(R-2)
[0051] As such, the first shifted stream has a lower CO concentration and a
higher CO2
concentration than the cooled reformed stream. The forward reaction of (R-2)
is exothermic,
resulting in the first shifted stream having a temperature higher than the
cooled reformed stream
entering the first shift reactor. The first shifted stream exiting the first
shift reactor can have a
temperature from, e.g., 335 C, 340 C, 350 C, 360 C, to 370 C, 380 C, 400
C, 420 C, to
440 C, 450 C, 460 C, 480 C, or even 500 C. The first shifted stream can
have an absolute
pressure substantially the same as the cooled reformed stream.
[0052] While a single stage of shift reactor may convert sufficient
amount of CO in the
cooled reformed stream to CO2 resulting in a low CO concentration in the first
shifted stream,
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Date Recue/Date Received 2022-12-09
it is preferable to include at least two stages of shift reactors in the
processes of this disclosure
to achieve a high level of conversion of CO to CO2. and eventually to produce
a Hz-rich fuel
gas stream with low CO concentration. It is further preferred that a
subsequent stage, such as
the second shift reactor downstream of the first shift reactor is operated at
a temperature lower
than the first shift reactor, whereby additional amount of CO in the first
shifted stream is further
converted into CO2 and additional amount of Hz is produced. To that end, the
first shifted
stream is preferably first cooled down in step (IV) to produce a cooled first
shifted stream.
Such cooling can be effected by one or more heat exchangers using one or more
cooling streams
having a temperature lower than the first shifted stream. In one preferred
embodiment, the first
shifted stream can be cooled by the hydrocarbon stream or a split stream
thereof to be fed into
the syngas producing unit. Alternatively or additionally, the first shifted
stream can be cooled
by a boiler water feed stream to produce a heated boiler water stream, a steam
stream, and/or a
water/steam mixture stream. The thus heated boiler water stream can be heated
in a boiler to
produce steam at various pressure. The thus heated boiler water stream or
steam stream can be
further heated by another process stream in another heat exchanger to produce
steam. In one
preferred embodiment, the heated boiler water stream and/or steam stream can
be fed into the
steam drum of the WHRU extracting heat from the reformed stream as described
above, where
it is further heated to produce the HPS stream. The cooled first shifted
stream can have a
temperature from, e.g., 150 C, 160 C, 170 C, 180 C, 190 C, 200 C, to 210
C, 220 C,
230 C, 240 C, or even 250 C, and a pressure substantially the same as the
first shifted stream.
[0053] The cooled first shifted stream is then subjected to a low-
temperature shifting in a
second shift reactor under a second set of shifting conditions to produce a
second shifted
stream. The first set of shifting conditions includes the presence of a second
shift catalyst,
which may be the same or different from the first shift catalyst. Any suitable
shift catalyst
known to one skilled in the art may be used. The forward reaction of the
following
preferentially occur in the first shift reactor:
Second Shift Catalyst
CO + H20 . CO2 + H2
(R-3)
[0054] As such, the second shifted stream has a lower CO concentration
and a higher CO2
concentration than the cooled first shifted stream. The forward reaction of (R-
3) is exothermic,
.. resulting in the second shifted stream having a temperature higher than the
cooled first shifted
stream entering the second shift reactor. The second shifted stream exiting
the first shift reactor
can have a temperature from, e.g., e.g., 150 C, 160 C, 170 C, 180 C, 190
C, 200 C, to
210 C, 220 C, 230 C, 240 C, 250 C, to 260 C, 270 C, 280 C, 290 C, or
even 300 C.
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Date Recue/Date Received 2022-12-09
The second shifted stream can have an absolute pressure substantially the same
as the cooled
first shifted stream.
[0055] The second shifted stream comprises H2, CO2, CO, steam, and
optionally CH4. In
step (VI), steam is then abated from it by cooling and separation. Similar to
step (IV) of cooling
the first shifted stream, such cooling of the second shifted stream can be
effected by one or
more heat exchangers using one or more cooling streams having a temperature
lower than the
second shifted stream. In one preferred embodiment, the second shifted stream
can be cooled
by the hydrocarbon stream or a split stream thereof to be fed into the syngas
producing unit.
Alternatively or additionally, the first shifted stream can be cooled by a
boiler water feed stream
to produce a heated boiler water stream, a steam stream, and/or a water/steam
mixture stream.
The thus heated boiler water stream can be heated in a boiler to produce steam
at various
pressure. The thus heated boiler water stream or steam stream, can be further
heated by another
process stream in another heat exchanger to produce steam. In one preferred
embodiment, the
heated boiler water stream and/or steam stream can be fed into the steam drum
of the WHRU
.. extracting heat from the reformed stream as described above, where it is
further heated to
produce the HPS stream. The cooled second shifted stream can preferably
comprise water
condensate, which can be separated to produce a crude gas mixture stream
comprising steam
at a significantly lower concentration than the second shifted stream exiting
the second shift
reactor.
[0056] The crude gas mixture stream thus consists essentially of CO2, H2,
optionally CH4
at various amounts, and steam and CO as minor components. The crude gas
mixture stream
can have an absolute pressure from, e.g., 700 kPa, 800 kPa, 800 kPa, 900 kPa,
1,000 kPa, to
1,500 kPa, 2,000 kPa, 2,500 kPa, 3,000 kPa, to 3,500 kPa, 4,000 kPa, 4,500
kPa, or even 5,000
kPa In step (VII), one can recover a portion of the CO2 therein to produce a
CO2 stream and a
H2-rich stream. Any suitable CO2 recovery process known to one skilled in the
art may be used
in step (VII), including but not limited to: (i) amine absorption and
regeneration process; ; (ii)
a cryogenic CO2 separation process; (iii) a membrane separation process; (iv)
a physical
absorption and regeneration process; and (iv) any combination any of (i),
(ii), and (iii) above.
In a preferred embodiment, an amine absorption and regeneration process may be
used. Due to
the elevated pressure of the crude gas mixture stream, the size of the CO2
recovery equipment
can be much smaller than otherwise required to recover CO2 from a gas mixture
at atmospheric
pressure.
[0057] The CO2 stream preferably comprises CO2 at a molar concentration
of from, e.g.,
90%, 91%, 92%, 93%, 94%, to 95%, 96%, 97%, 98%, or even 99%, based on the
total moles
- 20 -
Date Recue/Date Received 2022-12-09
of molecules in the CO2 stream. The CO2 stream can comprise at least one and
preferably all
of, on a molar basis: (i) e.g., from 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%,
0.8%, 0.9%, to
1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.5%, or even 5.0% of CO; (ii) e.g., from
0.1%, 0.2%,
0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, to 1.0%, 1.5%, 2.0%, 2.5%, 3.0%,
3.5%, 4.5%,
5.0%, 5.5%, or even 6.0% of 1120; and (iii) e.g., from 0.1%, 0.2%, 0.3%, 0.4%,
0.5%, 0.6%,
0.7%, 0.8%, 0.9%, to 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.5%, or even 5.0% of
CH4. The
CO2 stream can have an absolute pressure from, e.g., 200 kPa, 300 kPa, 400
kPa, 500 kPa, 600
kPa, 700 kPa, 800 kPa, 800 kPa, 900 kPa, 1,000 kPa, to 1,500 kPa, 2,000 kPa,
2,500 kPa, 3,000
kPa, to 3,500 kPa, 4,000 kPa, 4,500 kPa, or even 5,000 kPa, depending on the
CO2 recovery
process and equipment used. In a
preferred embodiment, where an amine
absorption/regeneration CO2 recovery unit is utilized, the CO2 may have an
absolute pressure
from e.g., 200 kPa, 250 kPa, 300 kPa, 350 kPa, to 400 kPa, 450 kPa, 500 kPa,
550 kPa, 560
kPa, 570 kPa, 580 kPa, 590 kPa, or even 600 kPa. In such embodiments where an
amine CO2
separation unit is utilized, the heat needed in the CO2/amine separation
column may be
advantageously provided at least partly, preferably primarily, preferably
entirely by the exhaust
steam stream having a pressure from 200 kPa to 1,050 kPa produced from the
extraction turbine
and/or back-pressure turbine as described above. The CO2 stream can be
compressed, liquefied,
conducted away, stored, sequestered, or utilized in any suitable applications
known to one
skilled in the art. In one embodiment, the CO2 stream, upon optional
compression, can be
conducted away in a CO2 pipeline. In another embodiment, the CO2 stream, upon
optional
compression and/or liquefaction, can be injected and stored in a geological
formation. In yet
another embodiment, the CO2 stream, upon optional compression and/or
liquefaction, can be
used in extracting hydrocarbons present in a geological formation. Another
exemplary use of
the CO2 stream is in food applications.
[0058] The Hz-
rich stream can have an absolute pressure from, e.g., 700 kPa, 800 kPa, 800
kPa, 900 kPa, 1,000 kPa, to 1,500 kPa, 2,000 kPa, 2,500 kPa, 3,000 kPa, to
3,500 kPa, 4,000
kPa, 4,500 kPa, or even 5,000 kPa. The Hz-rich stream preferably comprises Hz
at a molar
concentration of from, e.g., 80%, 81%, 82%, 83%, 84%, 85%, to 86%, 87%, 88%,
89%, 90%,
to 91%, 92%, 93%, 94%, 95%, to 96%, 97%, or even 98%, based on the total moles
of
molecules in the Hz-rich stream. The Hz-rich stream can comprise at least one
and preferably
all of, on a molar basis: (i) e.g., from 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%,
0.7%, 0.8%, 0.9%,
to 1.0%, 1.5%, 2.0%, 2.5%, or even 3.0%, of CO; (ii) e.g., from 0.1%, 0.2%,
0.3%, 0.4%, 0.5%,
to 0.6%, 0.7%, 0.8%, 0.9%, or even 1.0%, of CO2; and (iii) e.g., from 0.1%,
0.2%, 0.3%, 0.4%,
0.5%, 0.6%, 0.7%, 0.8%, 0.9%, to 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.5%, or
even 5.0%
- 21 -
Date Recue/Date Received 2022-12-09
of CH4. One specific example of a Hz-rich stream that may be produced from the
process of
this disclosure has the following molar composition: 0.25% of CO2; 1.75% of
CO; 93.87% of
Hz; 0.23% of Nz; 3.63% of CH4; and 0.29% of 1120.
[0059] Where an even higher purity Hz stream is desired, a portion of the
Hz-rich stream
can be further purified by using processes and technologies known to one
skilled in the art,
e.g., pressure-swing-separation.
[0060] Preferably, however, the Hz-rich stream, notwithstanding the
optional low
concentrations of CO, CO2. and CH4, is used as a fuel gas stream without
further purification
to provide heating in step (VIII) of the process in, e.g., industrial
applications. Due to the low
.. combined concentrations of CO, CO2. and CH4 therein, the flue gas stream
produced from
combusting the Hz-rich stream can comprise CO2 at a very low concentration,
resulting in low
CO2 emission to the atmosphere. Thus, the flue gas stream can comprise CO2 at
a molar
concentration from, e.g., 0.01%, 0.05%, to 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%,
0.7%, 0.8%,
0.9%, to 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, to 11%, 12%, 13%, 14%, 15%,
16%,
17%, 18%, 19%, or 20%, preferably < 10%, preferably < 5%, preferably < 3%,
based on the
total moles of CO2 and 1-120 in the flue gas stream. The combustion may be in
the presence of,
e.g., air, 02-enhanced air, high-purity 02, and the like, depending on the
specific application.
[0061] For use as a fuel gas stream, the Hz-rich stream may preferably
has an absolute
pressure of < 1,135 kPa (150 psig), preferably < 790 kPa (100 psig). To
achieve such low
pressure of the Hz-rich stream, it is feasible to design a syngas producing
unit upstream
comprising an SMR and/or an ATR operating under syngas producing conditions
including a
relatively low pressure, e.g., an absolute pressure of < 2,169 kPa (300 psig),
preferably < 1,825
kPa (250 psig). As mentioned above, a lower pressure in the reforming reactor
results in a
higher CH4 conversion in the reforming reactor, and hence a low residual CH4
concentration
in the Hz-rich stream.
[0062] Preferably, the Hz-rich stream is supplied to at least one,
preferably a majority,
preferably all, of the combustion devices used in the process/system for
producing the Hz-rich
stream. Thus, where the syngas producing unit comprises a pre-reformer
including a furnace
heated by one or more burners combusting a fuel gas, preferably a portion of
the Hz-rich stream
is supplied as at least a portion, preferably a majority, preferably the
entirety, of the fuel gas to
such burners. Where the syngas producing unit includes an SMR comprising one
or more SMR
burners combusting a SMR fuel, it is highly desirable to supply a portion of
the Hz-rich stream
as at least a portion, preferably a majority, preferably the entirety, of the
SMR fuel. Where the
Hz-rich stream production process/system uses an additional boiler or
auxiliary furnace
- 22 -
Date Recue/Date Received 2022-12-09
combusting a fuel gas, it is desirable supply a portion of the Hz-rich stream
as at least a portion,
preferably a majority, preferably the entirety, of the fuel gas. By combusting
the Hz-rich stream
and capturing the CO2 stream, the Hz-rich stream production process/system of
this disclosure
can reach a very low overall level of CO2 emission to the atmosphere.
[0063] Compared to existing syngas and/or Hz-rich fuel gas producing
processes, especially
those combusting a hydrocarbon-containing fuel, the Hz-rich fuel gas
production process as
described above has at least one of the following advantages: (i) lower
capital investment and
production cost due to, e.g., an absence of a PSA unit, a small-size CO2
recovery unit, and
operating the syngas producing unit, the first shift reactor, and the second
shift gas reactor
under relatively low pressure; and (ii) lower CO2 emission if the CO2 stream
is captured, stored,
sequestered, and/or utilized.
[0064] This disclosure is further illustrated by the exemplary but non-
limiting embodiments
shown in the drawings, which are described below. In the drawings, the same
reference numeral
may have similar meaning. In the drawings illustrating an inventive
process/system, where
multiple initially separate streams are shown to form a joint stream supplied
to a next step or
device, it should be understood to further include, where appropriate, an
alternative where at
least one of such multiple separate streams is supplied to the next step or
device separately.
Where multiple initially separate streams having similar compositions and/or
use applications
(steam streams generated from differing devices) are shown to form a joint
stream supplied to
multiple next steps or devices, it should be understood to include, where
appropriate,
alternatives where at least one of the separate streams and the joint stream
is supplied to at least
one of the multiple next steps or devices. Thus, where a steam stream X and a
steam stream Y,
initially separate and generated from differing devices but with similar
applications, are shown
to form a joint stream Z supplied to two separate turbines A and B, it should
be understood to
include alternatives where at least one of X, Y, and Z is supplied to at least
one of A and B,
including but not limited to the following: (i) only stream Z is supplied to A
and B; (ii) both of
X and Y are supplied, separately, to at least one of A and B; (iii) both of X
and Z are supplied,
separately, to at least one of A and B; (iv) both of Y and Z are supplied,
separately, to at least
one of A and B; and (v) only one of X and Y is supplied to at least one of A
and B. The
drawings are only for the purpose of illustrating certain embodiments of this
disclosure, and
one skilled in the art appreciates that alternatives thereof may fall within
the scope of this
disclosure.
- 23 -
Date Recue/Date Received 2022-12-09
FIG. 1 (Comparative)
[0065] FIG. 1 schematically illustrates the steam supply/consumption system
101 of an
olefins production plant including one or more steam cracker furnaces. One or
more Super-
HPS stream(s) 107 are produced from one or more steam cracker furnace(s) 103.
One or more
Super-HPS stream(s) 109, if needed, are produced from one or more auxiliary
steam boiler(s)
105. Streams 107 and 109 may be optionally combined, as shown, at a Super-HPS
header, from
which the Super-HPS stream can be distributed to equipment consuming steam. As
shown in
FIG. 1, one or more Super-HPS stream(s) 113, one or more Super-HPS stream(s)
115, and one
or more Super-HPS stream(s) 117 are supplied to one or more steam turbine(s)
119, one or
more steam turbine(s) 129, and one or more steam turbine(s) 141, respectively.
Steam turbine(s)
119 can drive one or more process gas compressor(s). Steam turbine(s) 129 can
drive one or
more propylene refrigeration compressors. Steam turbine(s) 141 can drive one
or more ethylene
refrigeration compressors. Surplus Super-HPS steam may be supplied to other
facilities/equipment/process 111 for consumption. From steam turbine(s) 119,
one or more
HPS stream(s) 121 may be exhausted. Stream(s) 121 can be used to provide
process heat, e.g.,
to a stream 125 in the olefins production plant or other facilities, or
supplied to a steam turbine
125 receiving an HPS stream and exhausting a MPS stream, or supplied to a
steam turbine 125
receiving an HPS stream and exhausting an LPS stream, to produce additional
mechanical work
which can be used to drive another compressor, pumps, and the like. From steam
turbine(s)
119, one or more condensable stream(s) 123 may be exhausted, which can be
condensed at
condenser(s) 127 to produced one or more condensed water stream(s) 128. From
steam
turbine(s) 129, one or more MPS stream(s) 131 may be exhausted. Stream(s) 131
can be used
to provide process heat, e.g., to a stream 133 in the olefins production plant
or other facilities,
or supplied to a steam turbine 133 receiving a MPS stream and exhausting an
LPS stream, to
produce additional mechanical work which can be used to drive another
compressor, pumps,
and the like. From steam turbine(s) 129, one or more condensable stream(s) 135
may be
exhausted, which are then condensed at condenser(s) 137 to produced one or
more condensed
water stream(s) 139. From steam turbine(s) 141, one or more LPS stream(s) 143
may be
exhausted. Stream(s) 143 can be used to provide process heat, e.g., to a
stream 145 in the olefins
production plant or other facilities. From steam turbine(s) 141, one or more
condensable
stream(s) 147 may be exhausted, which are then condensed at condenser(s) 149
to produced
one or more condensed water stream(s) 151. Condensed water streams 128, 139,
and 151 may
- 24 -
Date Recue/Date Received 2022-12-09
be combined and processed together at location 353, which can be subsequently
reused in the
facility.
FIG. 2
[0066] FIG. 2 schematically illustrates an exemplary steam supply/consumption
system 201
integrating the olefins production plant shown in FIG. 1 and an amine CO2
separation process.
As shown, one or more Super-HPS stream(s) 107 are produced from one or more
steam cracker
furnace(s) 103. One or more Super-HPS stream(s) 109, if needed, are produced
from one or
more auxiliary steam boiler(s) 105. Streams 107 and 109 may be optionally
combined, as
shown, at a Super-HPS header, from which the Super-HPS stream can be
distributed to
equipment consuming steam. As shown in FIG. 2, one or more Super-HPS stream(s)
113, one
or more Super-HPS stream(s) 115, and one or more Super-HPS stream(s) 117 are
supplied to
one or more steam turbine(s) 119, one or more steam turbine(s) 129, and one or
more steam
turbine(s) 141, respectively. Surplus Super-HPS steam may be supplied to
other
facilities/equipment/process 111 for consumption. Steam turbine(s) 119 can
drive one or more
process gas compressor(s). Steam turbine(s) 129 can drive one or more
propylene refrigeration
compressors. Steam turbine(s) 141 can drive one or more ethylene refrigeration
compressors.
From steam turbine(s) 119, one or more HPS stream(s) 121 may be exhausted.
Stream(s) 121
can be used to provide process heat, e.g., to a stream 125 in the olefins
production plant or
other facilities, or supplied to a steam turbine 125 receiving an HPS stream
and exhausting a
.. MPS stream, or supplied to a steam turbine 125 receiving an HPS stream and
exhausting an
LPS stream, to produce additional mechanical work which can be used to drive
another process
gas compressor, pumps, and the like. From steam turbine(s) 119, instead of one
or more
condensable stream(s) 123 shown in FIG. 1, one or more LPS stream(s) 203 may
be exhausted.
From steam turbine(s) 129, one or more MPS stream(s) 131 may be exhausted.
Stream(s) 131
can be used to provide process heat, e.g., to a stream 133 in the olefins
production plant or
other facilities, or supplied to a steam turbine 133 receiving a MPS stream
and exhausting an
LPS stream, to produce additional mechanical work which can be used to drive
another
compressor, pumps, and the like. From steam turbine(s) 129, instead of one or
more
condensable stream(s) 135, one or more LPS stream(s) 205 may be exhausted.
From steam
turbine(s) 141, one or more LPS stream(s) 143 may be exhausted. The LPS
streams thus
exhausted from various steam turbines, such as stream(s) 203, 205, and 143 may
be combined
and used to provide process heat, e.g., to a stream 145 in the olefins
production plant or other
facilities, or to the amine regenerator of an amine CO2 separation process
207. From steam
turbine(s) 141, one or more condensable stream(s) 147 may be exhausted, which
are then
- 25 -
Date Recue/Date Received 2022-12-09
condensed at condenser(s) 149 to produced one or more condensed water
stream(s) 151, which
can be processed at location 153, and subsequently reused in the facility.
EXAMPLES
Example 1 (Comparative)
[0067] FIG. 3 schematically illustrates a steam supply/consumption
configuration 301 of a
comparative olefins production plant including multiple steam crackers. As
shown, the plant
supplies superheated steams through lines 303, 305, 307, and 309 at the
following temperature
and pressures, respectively: 930 F and 1500 psig (Super-HPS); 700 F and 660
psig (HPS);
570 F and 225 psig (MPS); and 450 F and 50 psig (LPS). 1560 kilo-pounds/hour
("klb/hr")
of Super-HPS in stream 317 produced by a gas turbine generator unit 311, 340
klb/hr of Super-
HPS in stream 319 produced by the multiple steam cracker furnaces 313, and 596
klb/hr of
Super-HPS in stream 321 produced by boilers 315 are supplied to line 303. From
line 303, the
Super-HPS streams 325, 327, 329, 331, and 333 are supplied to steam turbines
335, 337, 339,
341, and heat exchanger 343 at the following flow rates, respectively: 879
klb/hr; 710 klb/hr,
745 klb/hr, 301 klb/hr, and 3 klb/hr. From line 303, 58 klb/hr of the Super-
HPS is exported to
other users 323. Steam streams entering steam turbines are expanded therein to
produce one or
more extracted streams and shaft power. The shaft power can be used to drive
various
equipment in the olefins production plant, such as process gas compressors,
propylene
refrigeration compressors, and pumps, and the like.
[0068] Line 305 receives an imported HPS stream 304 at 30 klb/hr, an HPS
stream 345
extracted from steam turbine 335 at 700 klb/hr, an HPS stream 349 extracted
from steam
turbine 337 at 585 klb/hr, an HPS stream 357 extracted from steam turbine 341
at 100 klb/hr,
an HPS stream 367 from heat exchanger 343 at 3 klb/hr, and an HPS stream 365
from a steam
drum 363 at 10 klb/hr. All four steam turbines 335, 337, 339, and 341 also
produce a
condensable steam stream condensed at a surface condenser 347, 351, 355, and
361,
respectively, at the following flow rates, respectively: 179 klb/hr, 124
klb/hr, 79 klb/hr, and
149 klb/hr. From line 305, HPS streams 371, 373, and 320 are supplied to steam
turbines 375
and 377 and other on-site users 322 at the following flow rates, respectively:
540 klb/hr, 127
klb/hr, and 68 klb/hr. From line 305, 695 klb/hr of HPS is exported to other
users 369.
[0069] Line 307 receives an MPS stream 379 extracted from steam turbine 375 at
540 klb/hr,
and an MPS stream 357 extracted from steam turbine 338 at 667 klb/hr. Steam
turbine 375
does not produce a condensable stream supplied to a surface condenser. From
line 307, MPS
streams 385, 387 and 330 are supplied to steam turbine 389, on-site users 393,
and on-site users
- 26 -
Date Recue/Date Received 2022-12-09
332 at the following flow rates, respectively: 324 klb/hr, 206 klb/hr, and 306
klb/hr. From line
307, 330 klb/hr of MPS is exported to other users 383.
[0070] Line 309 receives an imported LPS stream 310 at a flow rate of 12
klb/hr, an LPS
stream 379 extracted from steam turbine 389 at 324 klb/hr, an LPS stream 381
extracted from
steam turbine 377 at 127 klb/hr, and an LPS stream 395 extracted from steam
drum 397 at a
flow rate of 70 klb/hr. Neither of steam turbines 389 and 377 produces a
condensable stream
supplied to a surface condenser. From line 309, LPS streams 340 and 350 are
supplied to on-
site users 342 and 352, respectively, at the following flow rates,
respectively: 261 klb/hr, and
207 klb/hr.
[0071] In this Example 1, from the four major steam-turbines 335, 337, 339,
and 341, a total
of 530 klb/hr of steam is condensed, giving a total condenser duty of 520
MBtu/hr (152MW).
Example 2 (Inventive)
[0072] FIG. 4 schematically illustrates an inventive steam supply/consumption
configuration
401 of an olefins production plant modified from the plant of FIG. 3 and steam-
integrated with
an SMR. As shown in FIG. 4, the plant supplies superheated steams through
lines 303, 305,
307, and 309 at the following temperature and pressures, respectively: 930 F
and 1500 psig
(Super-HPS); 700 F and 660 psig (HPS); 570 F and 225 psig (MPS); and 450 F
and 50 psig
(LPS), the same as in FIG. 3. 1560 klb/hr of Super-HPS in stream 317 produced
by a gas
turbine generator unit 311, 540 klb/hr of Super-HPS in stream 319 produced by
the multiple
steam cracker furnaces 313, 262 klb/hr of Super-HPS in stream 421 produced by
boilers 415,
and 905 klb/hr of Super-HPS in stream 404 produced by an SMR 403 are supplied
to line 303.
From line 303, the Super-HPS streams 425, 427, 279, 431, and 333 are supplied
to steam
turbines 335, 337, 339, 341, and heat exchanger 343 at the following rates,
respectively: 951
klb/hr; 808 klb/hr, 1073 klb/hr, 373 klb/hr, and 3 klb/hr. From line 303, 58
klb/hr of the Super-
HPS is exported to other users 323.
[0073] Line 305 receives an imported HPS stream 304 at 30 klb/hr, an HPS
stream 445
extracted from steam turbine 335 at 630 klb/hr, an HPS stream 449 extracted
from steam
turbine 337 at 700 klb/hr, an HPS stream 453 extracted from steam turbine 339
at 407 klb/hr,
an HPS stream 457 extracted from steam turbine 341 at 149 klb/hr, an HPS
stream 367 from
heat exchanger 343 at 3 klb/hr, and an HPS stream 365 from a steam drum 363 at
10 klb/hr.
Only steam turbines 337 and 341 also produce a condensable steam stream
condensed at a
surface condenser 351 and 461, respectively, at the following flow rates,
respectively: 108
klb/hr and 89 klb/hr. From line 305, HPS streams 371 and 373 are supplied to
steam turbines
375 and 377 and other on-site users 322 at the following flow rates,
respectively: 540 klb/hr,
- 27 -
Date Recue/Date Received 2022-12-09
127 klb/hr, and 68 klb/hr. From line 305, 595 klb/hr of HPS is exported to
other users 369.
Additionally, from line 305, an HPS stream 405 at a flow rate of 499 klb/hr is
supplied to SMR
403.
[0074] Line 307 receives an MPS stream 379 extracted from steam turbine 375 at
540 klb/hr,
and an MPS stream 357 extracted from steam turbine 338 at 567 klb/hr. Steam
turbine 375
does not produce a condensable stream supplied to a surface condenser. From
line 307, MPS
streams 385, 387 and 330 are supplied to steam turbine 389, on-site users 393,
and on-site users
332 at the following flow rates, respectively: 324 klb/hr, 206 klb/hr, and 306
klb/hr. From line
307, 360 klb/hr of MPS is exported to other users 383.
[0075] Line 309 receives an imported LPS stream 310 at a flow rate of 12
klb/hr, an LPS
stream 379 extracted from steam turbine 389 at 324 klb/hr, an LPS stream 381
extracted from
steam turbine 377 at 127 klb/hr, and an LPS stream 395 extracted from steam
drum 397 at a
flow rate of 70 klb/hr. Neither of steam turbines 389 and 377 produces a
condensable stream
supplied to a surface condenser. From line 309, LPS streams 340 and 350 are
supplied to on-
site users 342 and 352, respectively, at the following flow rates,
respectively: 261 klb/hr, and
207 klb/hr. Additionally, from line 309, an LPS stream 407 at a flow rate of
487 klb/hr is
supplied to the amine regenerator of the amine CO2 capture unit associated
with SMR 403.
[0076] Thus, in this inventive Example 2, compared to Example 1, the number of
condensing
turbines is reduced from 4 to 2, the total duty of surface condensers is
reduced by 96.6 MW,
corresponding to a reduction of thermal energy released to the atmosphere of
96.6 MW. The
ratio of the reduction of thermal energy released to the atmosphere to the
total LP steam made
available to the amine unit is 68%, a highly significant percentage. See TABLE
I below for
operation parameters.
TABLE I
Example 1
Example 2
Comparative
Inventive
Total Power of Turbines 335, 337, 339, and 341 MW 128.9 128.9
Number of Condensing Turbines 4 2
Total Super-HPS Steam to Turbines tph 1,195 1,454
Total Duty of Surface Condensers MW 152.3 55.7
Reduction of Energy Loss to Atmosphere (A) MW 96.6
LP Steam made available to Amine Unit tph - 220.9
LP Steam made available to Amine Unit (B) MW - 141.2
Ratio: A/B % 68
.. [0077] This disclosure can include the following non-limiting embodiments:
[0078] Al. A process comprising:
- 28 -
Date Recue/Date Received 2022-12-09
(i) obtaining an exhaust steam stream having an absolute pressure from 200 kPa
to
1,050 kPa and shaft power from one or more extraction turbines and/or back-
pressure turbines,
wherein the shaft power drives a device located in a hydrocarbon processing
plant;
(ii) providing a gas mixture stream comprising CO2;
(iii) feeding the gas mixture stream and a lean-amine stream comprising an
amine into
an absorption column;
(iv) obtaining a CO2-rich amine stream and a CO2-depleted residual gas stream
from
the absorption column;
(v) feeding at least a portion of the CO2-rich amine stream into a separation
column;
(vi) heating the at least a portion of the CO2-rich amine stream in the
separation column
using the exhaust steam stream to produce a stream rich in CO2 and a stream
rich in the amine;
and
(vii) recycling at least a portion of the bottoms stream to the absorption
column as at
least a portion of the lean-amine stream.
[0079] A2. The process of Al, wherein the exhaust steam stream has an absolute
pressure
no higher than 450 kPa.
[0080] A3. The process of Al or A2, wherein the gas mixture stream comprises
H2, CO,
and CO2.
[0081] A4. The process of any of Al to A3, wherein the one or more extraction
turbine(s)
and/or back-pressure turbine(s) is located in an olefins production plant
including a steam
cracker, and the one or more extraction turbine(s) back-pressure turbine
drives a compressor
located in the olefins production plant.
[0082] AS. The process of any of Al to A4, wherein at least one of the one or
more
extraction turbine(s) and/or back-pressure turbine(s) comprises a back-
pressure turbine.
[0083] A6. The process of AS, wherein all of the one or more extraction
turbines and/or
back-pressure turbines are back-pressure turbines.
[0084] A7. The process of AS, wherein:
the exhaust steam stream provides a quantity of energy to the at least a
portion of the
CO2-rich amine stream in step (vi); and
at least 30% of the quantity of energy would have been lost to the atmosphere
in a
comparative process identical with the process except the back-pressure
turbine is substituted
by an extraction/condensing turbine with the identical power rating.
[0085] A8. The process of A8, wherein at least 50% of the quantity of energy
would have
been lost to the atmosphere in the comparative process.
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Date Recue/Date Received 2022-12-09
[0086] A9. The process of A8, wherein at least 70% of the quantity of energy
would have
been lost to the atmosphere in the comparative process.
[0087] A10. The process of any of Al to A9, wherein the gas mixture stream is
produced by
a syngas producing process comprising:
(A) supplying a hydrocarbon feed and a steam feed into a syngas producing unit
comprising a reforming reactor under syngas producing conditions to produce a
reformed
stream exiting the reforming reactor, wherein the syngas producing conditions
include the
presence of a reforming catalyst, and the reformed stream comprises H2, CO,
and steam;
(B) cooling the reformed stream by using a waste heat boiler ("WHB") to
produce a
cooled reformed stream and to generate a high-pressure steam ("HPS") stream;
(C) contacting the cooled reformed stream with a first shifting catalyst in a
first shift
reactor under a first set of shifting conditions to produce a first shifted
stream exiting the first
shift reactor, wherein the first shifted stream has a lower CO concentration
and a higher CO2
concentration than the first cooled reforming reactor effluent stream; and
(D) obtaining the gas mixture stream from the first shifted stream.
[0088] All. The process of A10, wherein step (D) comprises:
(D1) cooling the first shifted stream to obtain a cooled first shifted stream;
(D2) contacting the cooled first shifted stream with a second shifting
catalyst in a
second shift reactor under a second set of shifting conditions to produce a
second shifted stream
exiting the second shift reactor, wherein the second shifted stream has a
lower CO
concentration and a higher CO2 concentration than the cooled first shifted
stream;
(D3) abating the steam present in the second shifted stream to produce the gas
mixture
stream comprising CO2 and H2-
[0089] Al2. The process of All or Al2, wherein the syngas producing unit
comprises a
steam-methane-reformer ("SMR"), and/or an autothermal reformer ("ATR").
[0090] A13. The process of Al2, wherein:
the reforming reactor comprises a SMR; and
the SMR comprises: a plurality of SMR burners where a SMR fuel combusts to
supply
thermal energy to SMR; a radiant section heated by the thermal energy in which
the
hydrocarbon feed and steam reacts under the syngas producing conditions; a
convection section
heated by the thermal energy in which the hydrocarbon feed and steam are
preheated before
entering the radiant section.
[0091] A14. The process of A13, wherein the reformed stream has a temperature
from 750
to 900 C.
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Date Recue/Date Received 2022-12-09
[0092] A15. The process of A13 or A14, wherein the syngas producing process
further
comprises:
(E) heating the HPS stream generated in step (B) in the convection section of
the SMR
and/or an auxiliary furnace to obtain a super-heated HPS ("SH-HPS") stream
having at least
one of the following: a temperature from 350 C to 550 C, and a pressure from
4,000 kPa to
14,000 kPa.
[0093] A16. The process of Al2, wherein:
the reforming reactor comprises an ATR;
an 02 stream is fed into the ATR;
the ATR comprises a reaction vessel into which the hydrocarbon feed, the steam
feed,
and the 02 stream are supplied;
the reforming conditions comprises the presence of an ATR catalyst in the
reaction
vessel; and
the reformed stream has at least one of the following: a temperature from 800
C to
1,100 C; and an absolute pressure from 2,000 kPa to 5,000 kPa.
[0094] A17. The process of A16, further comprising:
(E') heating the HPS stream generated in step (B) in an auxiliary furnace to
obtain a
super-heated HPS ("SH-HPS") stream having at least one of the following: a
temperature from
350 C to 550 C, and a pressure from 4,000 kPa to 14,000 kPa.
[0095] A18. The process of any of A15 to A17, wherein a portion of the SH-HPS
stream
generated in step (E) or step (E') is supplied to the one or more extraction
turbine(s) and/or
back-pressure turbine(s) in step (i).
[0096] A19. The process of any of A10 to A17, further comprising:
(F1) expanding the at least a portion of the SH-HPS stream produced in step
(E) and/or
step (E') in a first stage steam turbine to produce shaft power and an
intermediate steam stream;
and
(F2) expanding at least a portion of the intermediate steam stream in a second
stage
turbine to produce the exhaust steam stream, wherein the second stage turbine
is an extraction
turbine and/or a back-pressure turbine.
[0097] A20. The process of A19, wherein the first stage turbine and/or the
second stage
turbine is selected from: (i) one or more turbines driving one or more process-
gas compressors
located on the olefins production plant; (ii) one or more turbines driving one
or more propylene
refrigeration compressors located on the olefins production plant; and (iii)
one or more turbines
driving one or more ethylene refrigeration compressors located on the olefins
production plant.
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Date Recue/Date Received 2022-12-09
[0098] A21. The process of A19 or A20, wherein a portion of the SH-HPS stream
generated
in step (E) and/or step (E') is supplied to a turbine driving a pump located
on the olefins
production plant.
[0099] A22. A process comprising:
(i) obtaining an exhaust steam stream having an absolute pressure from 200 kPa
to
1,050 kPa exhausted from one or more extraction turbine(s) and/or back-
pressure turbine(s)
located in an olefins production plant, wherein the extraction turbine(s)
and/or back-pressure
turbine(s) drives one or more of the following: a process-gas compressor; a
refrigeration
compressor; and combinations thereof;
(ii) providing a gas mixture stream comprising CO2;
(iii) feeding the gas mixture stream and a lean-amine stream comprising an
amine into
an absorption column;
(iv) obtaining a CO2-rich amine stream and a CO2-depleted residual gas stream
from
the absorption column;
(v) feeding at least a portion of the CO2-rich amine stream into a separation
column;
(vi) heating the at least a portion of the CO2-rich amine stream in the
separation column
using the exhaust steam stream to produce an overhead stream rich in CO2 and a
bottoms stream
rich in the amine; and
(vii) recycling at least a portion of the bottoms stream to the absorption
column as at
least a portion of the lean-amine stream.
[0100] A23. The process of A22, wherein step (i) comprises:
(ia) providing a super-heated high-pressure steam (SH-HPS) stream;
(ib) expanding at least a portion of the SH-HPS stream in the at least one
extraction
turbine(s) and/or back-pressure turbine(s) to obtain the exhaust steam stream.
[0101] A24. The process of A22, wherein step (i) comprises:
(ia') providing a super-heated high-pressure steam (SH-HPS) stream;
(ib') expanding at least a portion of the SH-HPS stream in a first stage steam
turbine to
an intermediate steam stream; and
(ic') expanding the intermediate steam stream in a second stage turbine to
obtain the
exhaust steam stream, wherein the second stage turbine is an extraction
turbine or a back-
pressure turbine.
[0102] A25. The process of A23 or A24, wherein the gas mixture stream is
produced by a
syngas producing process comprising:
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Date Recue/Date Received 2022-12-09
(A) supplying a hydrocarbon feed and a steam feed into a syngas producing unit
comprising a reforming reactor under syngas producing conditions to produce a
reformed
stream exiting the reforming reactor, wherein the syngas producing conditions
include the
presence of a reforming catalyst, and the reformed stream comprises H2, CO,
and steam;
(B) cooling the reformed stream by using a waste heat boiler ("WHB") to
produce a
cooled reformed stream and to generate a high-pressure steam ("HPS") stream;
(C) contacting the cooled reformed stream with a first shifting catalyst in a
first shift
reactor under a first set of shifting conditions to produce a first shifted
stream exiting the first
shift reactor, wherein the first shifted stream has a lower CO concentration
and a higher CO2
concentration than the first cooled reforming reactor effluent stream;
(D) obtaining the gas mixture stream from the first shifted stream;
(E) cooling the first shifted stream to obtain a cooled first shifted stream;
(F) contacting the cooled first shifted stream with a second shifting catalyst
in a second
shift reactor under a second set of shifting conditions to produce a second
shifted stream exiting
the second shift reactor, wherein the second shifted stream has a lower CO
concentration and
a higher CO2 concentration than the cooled first shifted stream;
(G) abating the steam present in the second shifted stream to produce the gas
mixture
stream comprising CO2 and Hz; the process further comprises:
(viii) heating the HPS stream generated in step (B) to obtain the SH-HPS
stream,
wherein the SH-HPS stream has at least one of the following: a temperature
from 350 C to
550 C, and a pressure from 4,000 kPa to 14,000 kPa.
[0103]
Various terms have been defined above. To the extent a term used in a claim is
not
defined above, it should be given the broadest definition persons in the
pertinent art have given
that term as reflected in at least one printed publication or issued patent.
Furthermore, all
patents, test procedures, and other documents cited in this application are
fully incorporated by
reference to the extent such disclosure is not inconsistent with this
application and for all
jurisdictions in which such incorporation is permitted.
[0104] While the foregoing is directed to embodiments of the present
invention, other and
further embodiments of the invention may be devised without departing from the
basic scope
thereof, and the scope thereof is determined by the claims that follow.
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Date Recue/Date Received 2022-12-09
