Note: Descriptions are shown in the official language in which they were submitted.
HYDROCARBON REFORMING PROCESSES WITH SHAFT POWER PRODUCTION
HELD
[0001] This disclosure relates to hydrocarbon reforming processes such as
natural gas
reforming processes for producing syngas and/or Hz-rich fuel gas. hi
particular, this disclosure
relates to hydrocarbon reforming processes integrated with an olefins
production plant.
BACKGROUND
[0002] 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 steam 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. Superheated steam streams are
generated to supply the
steam turbines.
[0003] Syngas, a mixture comprising primarily H2 and CO, optionally CO2, and
optionally
CH4, with various purity levels may be produced by using hydrocarbon steam
reforming such
as methane reforming in a syngas producing unit. The reforming may occur in a
reforming
reactor such as steam-methane-reformer ("SMR") where methane and steam, upon
being heated
to a high temperature, react in the presence of a reforming catalyst to
produce a reformed stream
comprising Hz, CO, and steam exiting the SMR. Heat energy can be recovered
from the high-
temperature reformed stream to produce steam at various pressures and a cooled
reformed
stream. Upon steam abatement, a first syngas stream may be produced from the
cooled reformed
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Date Recue/Date Received 2022-12-07
stream. Alternatively or additionally, the cooled reformed stream may undergo
a shift reaction
in the presence of a shift catalyst to convert a portion of CO and steam
therein into CO2 and H2
and to produce a shifted stream comprising H2, CO, CO2, and H20. Upon steam
abatement, a
second syngas comprising H2, CO, and CO2 can be produced. Upon CO2 recovery
from the
second syngas, a third syngas comprising H2 and CO may be produced. If the
third syngas
comprises a low concentration of CO, the third syngas is a Hz-rich gas
suitable as a fuel gas
stream. An Hz-rich gas may be further purified to produce H2 product with
various levels of
purity by using, e.g., a pressure-swing unit.
[0004] There is a need to improve energy efficiency of an olefins production
plant and a
syngas production unit. This disclosure satisfies this and other needs.
SUMMARY
[0005] A process for producing syngas and/or an Hz-rich fuel gas typically
comprises feeding
a hydrocarbon feed (e.g., a natural gas stream) 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, followed by recovering heat from the
reformed stream by
using a waste-heat recovery unit to produce a reformed stream and generate a
high-pressure
steam ("HPS") stream. It has been found that, by superheating the HPS stream,
expanding the
thus obtained super-heated HPS ("SH-HPS") stream to produce an expanded steam
stream
having a pressure equal to or greater than that of the steam feed, and then
supplying at least a
portion of the expanded steam stream to the reforming reactor, useful shaft
power can be
generated and an improved energy efficiency compared to existing processes can
be achieved.
When the process is integrated with an olefin production plant, one can
achieve considerably
improved energy efficiency and appreciably reduced CO2 emission from the
olefins production
plant compared to running the olefins production plant separately.
[0006] Thus, a first aspect of this disclosure relates to a 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 Hz, 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
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steam ("HIPS") steam; (C) heating the HIPS stream to obtain a super-heated
high-pressure steam
("SH-HPS") stream, wherein the SH-HPS 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 steam turbine to produce shaft power and an
expanded steam stream
having a pressure equal to or higher than the steam feed, wherein the at least
one steam turbine
is located in a hydrocarbon production plant; and (E) supplying at least a
portion of the
expanded steam stream as the steam feed in step (A).
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 schematically illustrates certain processes and systems for
producing a Hz-rich
stream including an SMR according to certain embodiments of this disclosure.
[0008] FIG. 2 schematically illustrates certain processes and systems for
producing a Hz-rich
steam including an ATR according to certain embodiments of this disclosure.
[0009] FIG. 3 schematically illustrates a process/system with steam
integration between a
syngas producing unit and an olefins production plant.
[0010] FIG. 4 schematically illustrates a comparative SMR waste heat recovery
process in
which the HPS stream generated by a waste-heat recovery unit is directly fed
into the SMR.
[0011] FIGs. 5, 6, and 7 schematically illustrate inventive waste heat
recovery processes
according to certain embodiments of this disclosure.
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.
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[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.
[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,"
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Date Recue/Date Received 2022-12-07
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
consisting essentially of Cm hydrocarbon(s). A "Cm-Cn hydrocarbon stream"
means a
hydrocarbon stream consisting essentially of Cm-Cn hydrocarbon(s).
[0018] 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.
[0019] "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.
[0020] "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 steam or mixture.
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[0021] A turbine is a steam turbine in this disclosure unless the context
clearly indicates
otherwise. A "hydrocarbon production plant" is a facility in which a
hydrocarbon product is
produced. Non-limiting examples of hydrocarbon production plants include: an
olefins
production plant that produce at least one olefin product such as ethylene and
propylene; and a
refinery that produces at least one hydrocarbon product, e.g., a benzene
product, a gasoline
product, and the like.
I. The Hydrocarbon Reforming Process and the Syngas Producing Unit
[0022] A first aspect of this disclosure relates to a hydrocarbon reforming
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 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 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).
[0023] 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 C I -C4
hydrocarbons
(preferably saturated), preferably consists essentially of Cl -C3 hydrocarbons
(preferably
saturated), preferably consists essentially of C I -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
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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 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.
[0024] 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
CH 4 + H20 - CO +3 H2
(R-1)
[0025] 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
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Date Recue/Date Received 2022-12-07
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.
100261 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, a convection section (e.g., an upper convection section),
a radiant section
(e.g., a lower radiant section), and one or more burners located in the
radiant section combusting
a fuel to produce a 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.,
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Date Recue/Date Received 2022-12-07
The International Energy Agency Greenhouse Gas R&D Program ("IEAGHG"), "Techno-
Economic Evaluation of SMR Based Standalone (Merchant) Plant with CCS",
February 2017;
and IEAGHG, "Reference data and supporting literature Reviews for SMR based
Hydrogen
production with CCS", 2017-TR3, March 2017.
[0027] 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 Syncorlm ATR available
from Haldor
Topsoe, having an address at Haldor Topsoes Alle 1, DK-2800, Kgs. Lyngby,
Denmark
("Topsoe"), may be used in the process of this disclosure.
[0028] 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.
[0029] The reformed stream existing 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
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Date Recue/Date Received 2022-12-07
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
steam is preferably a Super-HPS steam. The thus produced HPS stream is a
saturated steam
stream.
[0030] To make the HPS stream more useful, it may be further heated in step
(C) to produce
a superheated HPS ("SH-HPS") steam 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 MR 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 of 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
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 steam 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.
[0031] The steam turbine(s) in step (D) are present in a hydrocarbon
production plant, e.g.,
an oil refinery, an olefins production plant, a biofuel production plant, and
the like. These plants
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Date Recue/Date Received 2022-12-07
typically include equipment consuming shaft power produced by steam turbines,
e.g., gas
compressors at various power ratings, pumps, electricity generators, and the
like.
[0032] In step (D), at least a portion of the SH-HPS stream is expanded in
at least one 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.
[0033] 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 ("PGC"), a
propylene refrigeration compressor ("PRC") and an ethylene refrigeration
compressor ("ERC")
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 plants, and differentiates them from most
other
- 11 -
Date Recue/Date Received 2022-12-07
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.
[0034] 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).
[0035] 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
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Date Recue/Date Received 2022-12-07
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
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.
[0036] 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
significant capital costs
and operation costs.
[0037] 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 Hz, 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 appreciably lower CO2 emission than combustion of
natural gas.
- 1 3 -
Date Recue/Date Received 2022-12-07
II. The Plant and Process for Producing a Hz-Rich Fuel Gas
[0038] 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 Hz, CO, and steam; (II) cooling
the reformed
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. A system for producing such an Hz-rich stream,
preferably using a
process including steps (I) to (VII) above, may be called an Hz-rich fuel gas
production plant
in this disclosure.
[0039] Steps (I) and (II) may be identical with steps (A) and (B) of the
reforming process
described above.
[0040] 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.
Non-limiting examples of suitable shift catalyst for the first shifting
catalyst are high
- 14 -
Date Recue/Date Received 2022-12-07
temperature shift catalysts available from, e.g., Topsoe. The forward reaction
of the following
preferentially occur in the first shift reactor:
First Shift Catalyst
CO + H20 - CO2 +H2
(R-2)
[0041] 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.
100421 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,
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 H2 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
the boiler feedwater can be sent to the WHRU exchanger for further heating,
and any steam
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Date Recue/Date Received 2022-12-07
separated in the steam drum can be further superheated. 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 steam.
[0043] 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 second 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. Non-limiting examples of suitable catalyst
for the second
shifting catalyst are low temperature shift catalysts available from, e.g.,
Topsoe. The forward
reaction of the following preferentially occur in the first shift reactor:
Second Shift Catalyst
CO + H20 - _______________________________ - __ CO2 + H2
(R-3)
[0044] As such, the second shifted stream has a lower CO concentration and
a higher CO2
concentration than the cooled first shifted steam. 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. The
second shifted steam can have an absolute pressure substantially the same as
the cooled first
shifted stream.
[0045] 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 steam 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
- 16 -
Date Recue/Date Received 2022-12-07
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 the boiler
feedwater can
be sent to the WHRU exchanger for further heating, and any steam separated in
the steam drum
can be further superheated. 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.
[0046] The crude gas mixture stream thus consists essentially of CO2, Hz,
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 Hz-
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.
[0047] 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
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 H2O; 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., 150 kPa, 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
- 17 -
Date Recue/Date Received 2022-12-07
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., 150 kPa, 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. 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.
[0048] 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%
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
H2; 0.23% of I=12; 3.63% of CH4; and 0.29% of H20.
[0049] Where an even higher purity H2 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.
[0050] 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., residential,
office, and/or industrial
applications, preferably industrial applications. Due to the considerably
reduced combined
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Date Recue/Date Received 2022-12-07
concentrations of CO, CO2, and CH4 therein compared to conventional fuel gases
such as
natural gas, the flue gas stream produced from combusting the Hz-rich stream
can comprise
CO2 at a considerably reduced concentration, resulting in appreciably lower
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 H20
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.
[0051] 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 Oa (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.
[0052] 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 steam
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
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 an appreciably reduced level of CO2 emission to the atmosphere than
conventional
H2 production processes combusting natural gas.
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Date Recue/Date Received 2022-12-07
[0053] Compared to existing syngas and/or H2-rich fuel gas producing
processes, especially
those combusting a hydrocarbon-containing fuel, the H2-rich fuel gas
production process of this
disclosure 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) considerably lower CO2 emission if the CO2
stream is captured,
stored, sequestered, and/or utilized.
[0054] This disclosure is further illustrated by the exemplary but non-
limiting embodiments
shown in the drawings, which are described below. 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 meanings. 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.
FIG. 1
[0055] FIG. 1 schematically illustrates processes/systems 101 including an SMR
for
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Date Recue/Date Received 2022-12-07
producing a H2-rich fuel stream. As shown, a hydrocarbon feed stream 103
(e.g., a natural gas
stream comprising primarily CH4), which may contain CH4, C2+ hydrocarbons at
various
concentrations, and sulfur-containing compounds at various concentrations, is
first fed into an
optional sulfur removal unit 105 to produce a sulfur-abated stream 107, to
prevent poisoning
catalysts used in the downstream process steps such as the catalyst used in
the SMR unit
described below. Upon optional preheating via, e.g., a heat exchanger or a
furnace (not shown),
stream 107 is combined with an HPS stream 179 to form a hydrocarbon/steam
mixture stream
109. Upon optional preheating via, e.g., a heat exchanger or a furnace (not
shown), stream 109
can be then fed into a pre-reformer 111 which can be an adiabatic reactor
containing a pre-
reforming catalyst therein. On contacting the pre-reforming catalyst, the
heavier C2+
hydrocarbons are preferentially converted into methane (thus preventing the
formation of coke
in the downstream primary reforming reactor) to produce a pre-reforming
effluent 113
comprising methane and steam. Stream 113 is then fed into a tube 120a in the
upper section
114, sometimes called convection section, of an SMR 115, where it is heated.
SMR 115
comprises a lower section 116, sometimes called radiant section, housing one
or more tube
120b which is in fluid communication with tube 120a receiving the stream 113
heated in tube
120a. As shown, in certain embodiments, a tube 120a may exit the convection
section to the
exterior of the SMR furnace, and then connect with tube(s) 220b, which re-
enter the SMR
furnace. Multiple tubes 220b may be connected with one tube 220a via one or
more manifold
(not shown) outside of the SMR furnace housing, though one tube 220b is shown.
SMR 115
comprises one or more burners 118 in the radiant section 116, where a SMR fuel
combusts to
supply energy to the radiant section 116 and then the convection section 114
of SMR 115. For
the convenience of illustration, tubes 120a and 120b in the SMR are shown as
comprising
multiple straight segments. In practice, certain portions of tubes 120a and
120b, particularly
tube 120a, may be curved, or even form serpentine windings.
[0056] A reforming catalyst is loaded in tube(s) 120b in the radiant section
116. Due to the
proximity to the burner(s) 118, the hydrocarbon feed and steam, and the
reforming catalyst in
tube(s) 120b are heated/maintained at an elevated temperature. The forward
reaction of the
following preferentially occurs under syngas producing conditions:
Reforming Catalyst
CH4 + H20 - ______________________________ - .. CO +3 H2
(R-1)
- 21 -
Date Recue/Date Received 2022-12-07
[0057] In addition, various amounts of CO2 may be produced in tube(s) 120b.
Thus, a
reformed stream 121 comprising CO, Hz, residual CH4, residual H20 and
optionally various
amount of CO2 exits the outlet of tube(s) 120b from the SMR at a temperature
of e.g., from
750 C to 900 C and an absolute pressure from, e.g., 700 kPa to 3,500 kPa.
Stream 121 is then
cooled at a waste heat recovery unit ("WHRU") including a waste heat boiler
("WHB") 123
and a steam drum 171 to produce a cooled reformed stream 125 and to generate
an HPS stream
167. As shown, a water stream 163 flows from steam drum 171 to WHB 123, and a
steam-
water mixture stream 165 flows from WHB 123 to steam drum 171.
[0058] Stream 167, preferentially a saturated steam stream, can be then heated
in the
convection section 114 of SMR 115 to produce a super-heated, high-pressure
steam ("SP-HP")
steam stream 169, which can be fed into a steam header and supplied to any
suitable equipment
or process step. For example, as shown and described above, a split stream 179
of stream 169
can be combined with the sulfur-abated hydrocarbon feed stream 107 to form a
combined
stream 109, which is then fed into the pre-reformer 111. For another example,
a split stream
177 of stream 169 can be fed into a steam turbine 173, where it is expanded to
produce an
exhaust steam stream 183 and shaft power. The shaft power can be transferred,
via shaft 181,
to any suitable equipment 175 to produce useful mechanical work. One example
of equipment
175 is an electricity generator, which converts the mechanical work into
electrical energy
transmissible to any suitable local or distant electrical equipment. Exhaust
steam stream 183
can have various residual pressure and temperature suitable for, e.g., driving
additional steam
turbines, heating other equipment and/or streams, and the like.
[0059] As shown in FIG. 1, the cooled reformed stream 125, comprising CO, H2,
H2O, and
optionally CO2, is then fed into a first shift reactor 127. The first shift
reactor can be operated
under a first set of shifting conditions comprising the presence of a first
shift catalyst loaded
therein. Due to the relatively high temperature in the first set of shifting
conditions, the first
shift reactor 127 is sometimes called a high-temperature shift reactor. On
contacting the first
shift catalyst under the first set of shifting conditions, the forward
reaction of the following
preferentially occurs:
First Shift Catalyst
CO + H20 - ________________________________ - CO2 +H-,
(R-2)
[0060] Thus, a first shifted stream 129 comprising CO at a lower concentration
than stream
- 22 -
Date Recue/Date Received 2022-12-07
125 and CO2 at a higher concentration than stream 125 exits the first shift
reactor 127. Because
the forward reaction above is exothermic, stream 129 has a higher temperature
than stream 125
assuming the first shift reactor 127 is an adiabatic reactor.
[0061] The first shifted stream 129 can then be further cooled down at heat
exchanger 131 by
any suitable stream having a temperature lower than stream 129. As shown in
FIG. 1, in a
preferred embodiment, a boiler feed water stream 134, supplied from a boiler
feed water
treatment unit 133, is used to cool down stream 129. The thus heated boiler
feed water stream
135 exiting the heat exchanger 131 can be supplied to steam drum 171 and at
least partly
supplied to the WHB 123, to produce high-pressure steam stream 167 as
described earlier, or
to any other suitable steam generator. Alternatively or additionally (not
shown), the
hydrocarbon feed stream 103, or a portion thereof, may be heated by stream 129
at heat
exchanger 131 or another heat exchanger upstream or downstream of heat
exchanger 131.
[0062] The cooled first shifted stream 136 exiting heat exchanger 131,
comprising CO, H2,
H20, and CO2, is then fed into a second shift reactor 137. The second shift
reactor can be
operated under a second set of shifting conditions comprising the presence of
a second shift
catalyst loaded therein and a temperature lower than in the first shift
reactor 127. Due to the
lower temperature, the second shift reactor 137 is sometimes called a low-
temperature shift
reactor. On contacting the second shift catalyst under the second set of
shifting conditions, the
forward reaction of the following preferentially occurs:
Second Shift Catalyst
CO + H20 - _______________________________ CO2 + H2
(R-3)
[0063] Thus, a second shifted stream 139 comprising CO at a lower
concentration than stream
136 and CO2 at a higher concentration than stream 136 exits the second shift
reactor 137.
Because the forward reaction above is exothermic, stream 139 has a higher
temperature than
stream 136 assuming the second shift reactor 137 is an adiabatic reactor.
[0064] The second shifted stream 139 can then be further cooled down at heat
exchanger 141
by any suitable stream having a temperature lower than stream 139. In a
preferred embodiment,
a boiler feed water stream (not shown) supplied from a boiler feed water
treatment unit (e.g.,
unit 133) can be advantageously used to cool down stream 139. The thus heated
boiler feed
water stream exiting the heat exchanger 141 can be supplied (not shown) to
steam drum 171
and at least partly supplied to the WHB 123, to produce high-pressure steam
stream 167 as
- 23 -
Date Recue/Date Received 2022-12-07
described earlier, or to any other suitable steam generator. Alternatively or
additionally (not
shown), the hydrocarbon feed stream 103, or a portion thereof, may be heated
by stream 139 at
heat exchanger 141 or another heat exchanger upstream or downstream of heat
exchanger 141.
100651 The cooled stream 143 exiting heat exchanger 141 can be further cooled
at heat
exchanger 145 by any suitable cooling medium having a lower temperature than
stream 143,
e.g., a cooling water stream, ambient air (using an air-fin cooler, e.g.), and
the like. Preferably,
a portion of the residual steam in stream 143 is condensed to liquid water in
stream 147, which
can be fed into a separator 149 to obtain a condensate stream 151 and a vapor
stream 153. The
steam-abated stream 153, a crude gas mixture, comprises primarily H2 and CO2,
and optionally
minor amount of residual CH4 and CO.
100661 Stream 153 can then be supplied into a CO2 recovery unit 155 to produce
a CO2 stream
157 and an Hz-rich stream 159. Any suitable CO2 recovery unit known in the art
may be used.
A preferred CO2 recovery unit is an amine absorption and regeneration unit,
where the crude
gas mixture stream 153 contacts a counter-current stream of amine which
absorbs the CO2,
which is subsequently released from the amine upon heating ("regeneration").
The CO2 stream
157 can be supplied to a CO2 pipeline and conducted away. The CO2 stream 157
can be
compressed, liquefied, stored, sequestered, or utilized in manners known to
one skilled in the
art.
100671 The 112-rich stream 159 can advantageously comprise Hz at a molar
concentration
from, e.g., 80%, 81%, 82%, 83%, 84%, 85%, to 86%, 87%, 88%, 89%, 90%, to 91%,
92%,
93%, 94%, 95%, to 96%, 97%, 98%, 99%, based on the total moles of molecules in
stream 159.
In addition to Hz, stream 159 may comprise: (i) CH4 at a molar concentration
thereof based on
the total moles of molecules in stream 159, from, e.g., 0.1%, 0.3%, 0.5%,
0.8%, to 1%, 2%, 3%,
4%, or 5%; (ii) CO at a molar concentration thereof based on the total moles
of molecules in
stream 159, from, e.g., 0.1%, 0.3%, 0.5%, 0.8%, to 1%, 2%, or 3%; and (iii)
CO2 at a molar
concentration thereof based on the total moles of molecules in stream 159,
from, e.g., 0.1%,
0.2%, 0.3%, 0.4%, 0.5%, to 0.6%, 0.7%, 0.8%, 0.9%, or 1%. Stream 159 can be
advantageously
used as a fuel gas for residential, office, and/or industrial heating,
preferably industrial heating.
Due to the high concentration of H2 and low concentration of carbon-containing
molecules
therein, the combustion of stream 159 in the presence of an oxidant such as
air, oxygen, and the
like, can produce a flue gas stream comprising CO2 at a low concentration. In
certain
- 24 -
Date Recue/Date Received 2022-12-07
embodiments, the flue gas stream can comprises CO2 at a molar concentration
based on the
total moles of H20 and CO2 in the flue gas stream of no greater than 20%
(e.g., from 0.1%,
0.2%, 0.4%, 0.5%, to 0.6%, 0.8%, 1%, to 2%, 4%, 5%, to 6%, 8%, 10%, to 12%,
14%, 15%, to
16%, 18 mol%, or 20%). The flue gas stream can be advantageously exhausted
into the
atmosphere without the need to separate and capture CO2 therefrom.
[0068] In a preferred embodiment, as shown in FIG. 1, a split stream 117 of
stream 159 can
be supplied to the SMR 115, where it is combusted in burner(s) 118 to supply
thermal energy
to the SMR 115 heating the lower radiant section 116 and tube(s) 120b therein
and the
convection section 114 and tube 120a therein. The flue gas stream 119 exiting
the SMR 115
comprises CO2 at a low concentration, and therefore can be exhausted into the
atmosphere
without the need to separate and capture CO2 therefrom.
FIG. 2
[0069] FIG. 2 schematically illustrates processes/systems 201 including an AIR
for
producing a H2-rich fuel stream. As shown, a hydrocarbon feed stream 203
(e.g., a natural gas
stream comprising primarily CH4), which may contain CH4, C2+ hydrocarbons at
various
concentrations, and sulfur-containing compounds at various concentrations, is
first fed into an
optional sulfur removal unit 205 to produce a sulfur-abated stream 206, to
prevent poisoning
catalysts used in the downstream process steps such as the catalyst used in
the pre-reformer and
the ATR unit described below. Upon optional preheating via, e.g., a heat
exchanger (not shown)
or a furnace 287 a heated stream 207 is produced. Stream 207 is then combined
with an HPS
steam 279 to form a hydrocarbon/steam mixture stream 209. Upon optional
preheating via,
e.g., a heat exchanger or a furnace (not shown), stream 209 can be then fed
into a pre-reformer
211 which can be an adiabatic reactor containing a pre-reforming catalyst
therein. On contacting
the pre-reforming catalyst, the heavier C2+ hydrocarbons are preferentially
converted into
methane (thus preventing the formation of coke in the downstream primary
reforming reactor)
to produce a pre-reforming effluent 213 comprising methane and steam. Upon
optional heating
in furnace 287, stream 213 becomes a heated stream 212, which is then fed into
an ATR 215,
an 02 stream 216, which may be produced by air separation, is also fed into
ATR 215.
[0070] A forming catalyst is loaded in ATR 215. On contacting the reforming
catalyst, the
forward reaction of the following preferentially occurs under syngas producing
conditions:
- 25 -
Date Recue/Date Received 2022-12-07
Reforming Catalyst
CH4+ H20 - CO + 3 H2
(R-1)
[0071] In addition, various amounts of CO2 may be produced in the ATR. Thus, a
reformed
stream 221 comprising CO, Hz, residual H20, optionally residual CH4 at various
concentrations,
and optionally various amount of CO2 exits ATR 115 at a temperature of e.g.,
from 800 C to
1200 C and an absolute pressure from 700 kPa to 5,000 kPa. Stream 221 is then
cooled at a
waste heat recovery unit ("WHRU") including a waste heat boiler ("WHB") 223
and a steam
drum 264 to produce a cooled reformed stream 225 and to generate an HPS stream
267. As
shown, a water stream 263 flows from steam drum 264 to WHB 223, and a steam-
water stream
265 flows from WHB 223 to steam drum 264.
[0072] Stream 267, preferentially a saturated steam stream, can be then heated
in an auxiliary
furnace 289 to produce a super-heated, high-pressure steam ("SH-HPS") stream
269, which can
be fed into a steam header and supplied to any suitable equipment or process
step. Furnace 289
may be the same furnace as furnace 287 or a separate furnace. For example, as
shown and
described above, a split stream 279 of stream 269 can be combined with the
sulfur-abated
hydrocarbon feed stream 207 to form a combined stream 209, which is then fed
into the pre-
reformer 211. For another example, a split stream 277 of stream 269 can be fed
into a steam
turbine 274, where it is expanded to produce an exhaust steam stream 283 and
shaft power. The
shaft power can be transferred, via shaft 281, to any suitable equipment 275
to produce useful
mechanical work. One example of equipment 275 is an electricity generator,
which converts
the mechanical work into electrical energy transmissible to any suitable local
or distant
electrical equipment. Exhaust steam stream 283 can have various residual
pressure and
temperature suitable for, e.g., driving additional steam turbines, heating
other equipment and/or
streams, and the like.
[0073] As shown in FIG. 2, the cooled reformed stream 225, comprising CO, Hz,
H2O, and
optionally CO2, is then fed into a first shift reactor 227. The first shift
reactor can be operated
under a first set of shifting conditions comprising the presence of a first
shift catalyst loaded
therein. Due to the relatively high temperature in the first set of shifting
conditions, the first
shift reactor 227 is sometimes called a high-temperature shift reactor. On
contacting the first
shift catalyst under the first set of shifting conditions, the forward
reaction of the following
preferentially occurs:
- 26 -
Date Recue/Date Received 2022-12-07
First Shift Catalyst
CO + H20 CO2 + H2
(R-2)
[0074] Thus, a first shifted stream 229 comprising CO at a lower concentration
than stream
225 and CO2 at a higher concentration than stream 225 exits the first shift
reactor 227. Because
the forward reaction above is exothermic, stream 229 has a higher temperature
than stream 225
assuming the first shift reactor 227 is an adiabatic reactor.
[0075] The first shifted stream 229 can then be further cooled down at heat
exchanger 231 by
any suitable stream having a temperature lower than stream 229. As shown in
FIG. 2, in a
preferred embodiment, a boiler feed water stream 234, supplied from a boiler
feed water
treatment unit 233, can be used to cool down stream 229. The thus heated
boiler feed water
stream 235 exiting the heat exchanger 231 can be supplied to steam drum 264
and at least partly
subsequently supplied to the WHB 223, to produce high-pressure steam stream
267 as described
earlier, or to any other suitable steam generator. Alternatively or
additionally (not shown), the
hydrocarbon feed stream 203, or a portion thereof, may be heated by stream 229
at heat
exchanger 231 or another heat exchanger upstream or downstream of heat
exchanger 231.
[0076] The cooled first shifted stream 235 exiting heat exchanger 231,
comprising CO, H2,
H20, and CO2, is then fed into a second shift reactor 237. The second shift
reactor can be
operated under a second set of shifting conditions comprising the presence of
a second shift
catalyst loaded therein and a temperature lower than in the first shift
reactor 227. Due to the
lower temperature, the second shift reactor 237 is sometimes called a low-
temperature shift
reactor. On contacting the second shift catalyst under the second set of
shifting conditions, the
forward reaction of the following preferentially occurs:
Second Shift Catalyst
CO + H20 - CO2 +H2
(R-3)
[0077] Thus, a second shifted stream 239 comprising CO at a lower
concentration than stream
235 and CO2 at a higher concentration than stream 235 exits the second shift
reactor 237.
Because the forward reaction above is exothermic, stream 239 has a higher
temperature than
stream 236 assuming the second shift reactor 237 is an adiabatic reactor.
100781 The second shifted stream 239 can then be further cooled down at heat
exchanger 241
by any suitable stream having a temperature lower than stream 239. In a
preferred embodiment,
a boiler feed water stream (not shown) supplied from a boiler feed water
treatment unit (e.g.,
- 27 -
Date Recue/Date Received 2022-12-07
unit 233) can be advantageously used to cool down stream 239. The thus heated
boiler feed
water stream exiting the heat exchanger 241 can be supplied (not shown) to
steam drum 264
and at least partly supplied to the WHB 223, to produce high-pressure steam
stream 267 as
described earlier, or to any other suitable steam generator. Alternatively or
additionally (not
shown), the hydrocarbon feed stream 203, or a portion thereof, may be heated
by stream 239 at
heat exchanger 241 or another heat exchanger upstream or downstream of heat
exchanger 241.
[0079] The cooled stream 243 exiting heat exchanger 241 can be further cooled
at heat
exchanger 245 by any suitable cooling medium having a lower temperature than
stream 243,
e.g., a cooling water stream, ambient air (using an air-fin cooler, e.g.), and
the like. Preferably,
a portion of the residual steam in stream 243 is condensed to liquid water in
stream 247, which
can be fed into a separator 249 to obtain a condensate stream 251 and a vapor
stream 253. The
steam-abated stream 253, a crude gas mixture stream, comprises primarily H2
and CO2, and
optionally minor amount of residual CH4 and CO.
[0080] Stream 253 can then be supplied into a CO2 recovery unit 255 to produce
a CO2 stream
257 and an Hz-rich stream 259. Any suitable CO2 recovery unit known in the art
may be used.
A preferred CO2 recovery unit is an amine absorption and regeneration unit,
where the crude
gas mixture stream 253 contacts a counter-current stream of amine which
absorbs the CO2,
which is subsequently released from the amine upon heating ("regeneration").
The CO2 stream
257 can be supplied to a CO2 pipeline and conducted away. The CO2 stream 257
can be
compressed, liquefied, stored, sequestered, or utilized in manners known to
one skilled in the
art.
[0081] The Hz-rich stream 259 can advantageously comprise H2 at a molar
concentration
from, e.g., 80%, 81%, 82%, 83%, 84%, 85%, to 86%, 87%, 88%, 89%, 90%, to 91%,
92%,
93%, 94%, 95%, to 96%, 97%, 98%, 99%, based on the total moles of molecules in
stream 259.
In addition to Hz, stream 259 may comprise: (i) CH4 at a molar concentration
thereof based on
the total moles of molecules in stream 259, from, e.g., 0.1%, 0.3%, 0.5%,
0.8%, to 1%, 2%, 3%,
4%, or 5%; (ii) CO at a molar concentration thereof based on the total moles
of molecules in
stream 259, from, e.g., 0.1%, 0.3%, 0.5%, 0.8%, to 1%, 2%, or 3%; and (iii)
CO2 at a molar
concentration thereof based on the total moles of molecules in stream 259,
from, e.g., 0.1%,
0.2%, 0.3%, 0.4%, 0.5%, to 0.6%, 0.7%, 0.8%, 0.9%, or 1%. Stream 259 can be
advantageously
used as a fuel gas for residential, office, and/or industrial heating. Due to
the high concentration
- 28 -
Date Recue/Date Received 2022-12-07
of H2 and low concentration of carbon-containing molecules therein, the
combustion of stream
259 in the presence of an oxidant such as air, oxygen, and the like, can
produce a flue gas stream
comprising CO2 at a low concentration. In certain embodiments, the flue gas
stream can
comprises CO2 at a molar concentration based on the total moles of H20 and CO2
in the flue
gas stream of no greater than 20% (e.g., from 0.1%, 0.2%, 0.4%, 0.5%, to 0.6%,
0.8%, 1%, to
2%, 4%, 5%, to 6%, 8%, 10%, to 12%, 14%, 15%, to 16%, 18 mol%, or 20%). The
flue gas
stream can be advantageously exhausted into the atmosphere without the need to
separate and
capture CO2 therefrom.
[0082] In a preferred embodiment, as shown in FIG. 2, a split stream 272 of
stream 262
(which is a split stream of stream 259) can be supplied to furnace 287, where
it is combusted to
preheat the de-sulfured hydrocarbon stream 206, and a split stream 271 of
stream 262 can be
supplied to furnace 289, where it is combusted to superheat steam stream 267.
The flue gas
streams 219 and 291 exiting furnaces 287 and 289 comprise CO2 at a low
concentration, and
therefore can be exhausted into the atmosphere without the need to separate
and capture CO2
therefrom.
FIG. 3
[0083] FIG. 3 schematically illustrates an inventive process/system 301 with
advantageous
steam integration between a syngas or Hz-rich fuel gas production unit and an
olefins production
plant including a stream cracker furnace. An SH-HPS stream (preferably a Super-
HPS stream)
307 is generated from the WHRU of a syngas and/or H2-rich fuel gas production
process 303
as described above. One or more SH-HPS stream(s) (preferably Super-HPS
stream(s)) 308 are
produced from one or more steam cracker furnace(s) 304. One or more SH-HPS
stream(s)
(preferably Super-HPS stream(s)) 309, if needed, are produced from one or more
auxiliary
steam boiler(s) 305. Streams 307, 308, and 309 may be optionally combined, as
shown, at an
HPS (preferably Super-HPS) header, from which the SH-HPS (preferably Super-
HPS) can be
distributed to equipment consuming steam. As shown in FIG. 3, one or more HPS
(preferably
Super-HPS) stream(s) 313, one or more HPS (preferably Super-HPS) stream(s)
315, and one
or more HPS (preferably Super-HPS) stream(s) 317 are supplied to one or more
steam turbine(s)
319, one or more steam turbine(s) 329, and one or more steam turbine(s) 341,
respectively.
Steam turbine(s) 319 can drive one or more process gas compressor(s). Steam
turbine(s) 329
can drive one or more propylene refrigeration compressors. Steam turbine(s)
341 can drive one
- 29 -
Date Recue/Date Received 2022-12-07
or more ethylene refrigeration compressors. From steam turbine(s) 319, one or
more HPS
stream(s) 321 may be exhausted. Stream(s) 321 can be used to provide process
heat, e.g., to a
steam 325 in the olefins production plant or other facilities, or supplied to
a steam turbine 325
receiving an HPS stream and exhausting a MPS stream, or supplied to a steam
turbine 325
receiving an HPS stream and exhausting a 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) 319, one or more condensable stream(s) 323 may be exhausted, which
can be
condensed at condenser(s) 327 to produced one or more condensed water steam(s)
328. From
steam turbine(s) 329, one or more MPS stream(s) 331 may be exhausted.
Stream(s) 331 can be
used to provide process heat, e.g., to a stream 333 in the olefins production
plant or other
facilities, or supplied to a steam turbine 333 receiving a MPS stream and
exhausting a LPS
stream, to produce additional mechanical work which can be used to drive
another compressor,
pumps, and the like. From steam turbine(s) 329, one or more condensable
stream(s) 335 may
be exhausted, which are then condensed at condenser(s) 337 to produced one or
more
condensed water stream(s) 339. From steam turbine(s) 341, one or more LPS
stream(s) 343
may be exhausted. Stream(s) 343 can be used to provide process heat, e.g., to
a stream 345 in
the olefins production plant or other facilities. From steam turbine(s) 341,
one or more
condensable stream(s) 347 may be exhausted, which are then condensed at
condenser(s) 349 to
produced one or more condensed water stream(s) 351. Condensed water streams
328, 339, and
351 may be combined and processed together at location 353, which can be
subsequently reused
in the facility. Without steam 307, to satisfy the steam consumption needs of
the various steam
turbines driving the various compressors, pumps, generators, and process
heating, boiler(s) 305
are required, which consume considerable amount of fuel and may produce
considerable
amount of CO2 emission if a hydrocarbon fuel is used. With stream 307 supplied
from a syngas
and/or Hz-rich fuel gas production unit 303 integrated into the
process/system, to satisfy the
steam consumption needs of the same steam turbines and process heating,
boiler(s) 305 is
required at a reduced size, or may be eliminated entirely, resulting in
reduced fuel consumption
in and reduced CO2 emission from the olefins production plant.
FIG. 4 (Comparative)
[0084] FIG. 4 schematically illustrates a comparative SMR waste heat recovery
process/system 401 in the prior art. A natural gas feed stream 403 at a flow
rate of 83.6 tons per
- 30 -
Date Recue/Date Received 2022-12-07
hour ("tph") and a steam stream 405 having a temperature of 378 C, an
absolute pressure of
3,500 kPa, and a flow rate of 238.9 tph are fed into an Hz-rich fuel gas
production unit 407.
Unit 407 comprises an SMR in which the natural gas/steam mixture is heated to
an elevated
temperature and reformed under syngas producing conditions to produce a
reformed stream
comprising H2, CO, and residual CH4, a waste-heat recovery unit ("WHRU")
cooling the
reformed stream and producing an HPS stream 421 with a flow rate of 435.8 tph
and an absolute
pressure of 3,500 kPa and temperature of 378 C, a shift reactor receiving the
cooled reformed
steam to convert a portion of the CO in the cooled reformed steam to CO2 and
to produce a
shifted stream, a steam abatement unit for removing H20 from the shifted
stream to produce a
crude gas mixture stream 413 comprising Hz, CO2, and CH4. Steam 413 is then
fed into a CO2
recovery unit 415 using an amine absorption/regeneration process, to produce a
CO2 stream
417 and a Hz-rich stream 419. A split stream 409 of stream 419 is fed into the
SMR and
combusted to heat the SMR and produce a flue gas having a low CO2
concentration. Another
split stream 411 of stream 419 can be supplied as fuel gas to other equipment
where it can be
combusted to provide heating. The CO2 stream 417 can be optionally compressed,
liquefied,
conducted away, stored, sequestered, or utilized.
[0085] A split stream 405 of HPS stream 421, with a flow rate of 238.9 tph, is
fed into the
SMR of unit 407. Another split stream 423 of stream 421, with a flow rate of
196.9 tph, is
supplied to a steam turbine 425 having an isentropic efficiency of 75%, where
it expands to
produce 18.6 megawatt ("MW") of shaft power, which can be used to drive a
generator, and an
LPS stream at a flow rate of 196.9 tph. The generator is sometimes called a
"power island" in
a SMR hydrogen plant. The LPS stream can be supplied to the CO2 recovery unit
415 to provide
heat needed to regenerate the amine.
FIG. 5
[0086] FIG. 5 schematically illustrates an inventive waste heat recovery
process/system 501
of this disclosure. A natural gas feed stream 503 at a flow rate of 83.6 tph
and a steam stream
505 having a temperature of 378 C, an absolute pressure of 3,500 kPa, and a
flow rate of 238.9
tph are fed into an Hz-rich fuel gas production unit 507, which is similar to
the unit 407 in FIG.
4. Unit 507 comprises an SMR in which the natural gas/steam mixture is heated
to an elevated
temperature and reformed under syngas producing conditions to produce a
reformed stream
comprising H2, CO, and residual CH4, a WHRU cooling the reformed stream and
producing an
- 31 -
Date Recue/Date Received 2022-12-07
Super-HPS stream 521 subsequently superheated to 520 C with a flow rate of
404.6 tph and
an absolute pressure of 12,100 kPa, a shift reactor receiving the cooled
reformed stream to
convert a portion of the CO in the cooled reformed stream to CO2 and to
produce a shifted
stream, a steam abatement unit for removing H20 from the shifted stream to
produce a crude
gas mixture stream 513 comprising Hz, CO2, and CH4. Stream 513 is then fed
into a CO2
recovery unit 515 using an amine absorption/regeneration process, to produce a
CO2 stream
517 and a Hz-rich stream 519. A split stream 509 of stream 519 is fed into the
SMR, and
combusted to heat the SMR and produce a flue gas having a low CO2
concentration. Another
split stream 511 of stream 519 can be supplied as fuel gas to other equipment
where it can be
combusted to provide heating. The CO2 stream 517 can be optionally compressed,
liquefied,
conducted away, stored, sequestered, or utilized.
100871 The superheated Super-HPS stream 521, with a flow rate of 404.6 tph, is
fed into a
steam turbine 525 having an isentropic efficiency of 75%, where it expands to
produce an HPS
steam 505 having the temperature and flow rate as described above, an LPS
stream 627, and
41.5 MW of shaft power rotating about shaft 529, an increase of 22.9 MW
(30,700 hp) over the
arrangement of FIG. 4 above. The increased shaft power can be advantageously
used to drive a
generator or a major compressor such as a process gas compressor, a propylene
refrigeration
compressor, and/or an ethylene refrigeration compressor in an olefins
production plant. Such
an arrangement requires a re-balancing of the extraction levels of the major
steam turbines in
the plant design. This activity of balancing the various steam levels of an
olefin plant multi-
pressure steam system is well known to those familiar with olefin plant
design. By generating
the additional 22.9 MW of shaft power from steam generated in the SMR, less
SHP steam is
required from the boilers on the olefins production plant, with a
corresponding saving in boiler
fuel consumption and reduction in boiler CO2 emissions. The HPS stream 505 is
fed into the
SMR as the steam feed. The LPS stream 527, at a flow rate of 165.7 tph, can be
supplied to the
CO2 recovery unit 515 to provide heat needed to regenerate the amine.
FIG. 6
[0088] FIG. 6 schematically illustrates an inventive waste heat recovery
process/system 601
of this disclosure. A natural gas feed stream 603 at a flow rate of 83.6 tph
and an MPS stream
605 having a temperature of 378 C, an absolute pressure of 1,600 kPa, and a
flow rate of 238.9
tph are fed into an Hz-rich fuel gas production unit 607, which is similar to
the unit 407 in FIG.
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Date Recue/Date Received 2022-12-07
4. Unit 607 comprises an SMR operated at a lower pressure than the SMR in the
process of FIG.
4 to produce a reformed stream at a lower pressure than in the process of FIG.
4 to increase CH4
conversion, a WHRU cooling the reformed stream and producing an Super-HPS
stream 621 at
12,446 kPa absolute pressure, subsequently superheated to 520 C with a flow
rate of 404.6 tph
and an absolute pressure of about 12,100 kPa, a shift reactor receiving the
cooled reformed
stream to convert a portion of the CO in the cooled reformed stream to CO2 and
to produce a
shifted stream, a steam abatement unit for removing H20 from the shifted
stream to produce a
crude gas mixture stream 613 comprising Hz, CO2, and CH4. Stream 613 is then
fed into a CO2
recovery unit 615 using an amine absorption/regeneration process, to produce a
CO2 stream
617 and a Hz-rich stream 619. A split stream 609 of stream 619 is fed into the
SMR, and
combusted to heat the SMR and produce a flue gas having a low CO2
concentration. Another
split stream 611 of stream 619 can be supplied as fuel gas to other equipment
where it can be
combusted to provide heating. The CO2 stream 617 can be optionally compressed,
liquefied,
conducted away, stored, sequestered, or utilized.
[0089] The Super-HPS stream 621, with a flow rate of 404.6 tph, is fed into a
steam turbine
625, where it expands to produce an MPS stream 605 having the temperature and
pressure and
flow rate described above, an LPS stream 627, and 52.9 MW of shaft power
rotating about shaft
629. The shaft power, 34.3 MW (46,000 hp) higher compared to the process of
FIG. 4, can be
advantageously used to drive a generator or a major compressor such as a
process gas
compressor, a propylene refrigeration compressor, and/or an ethylene
refrigeration compressor
in an olefins production plant. As such, less Super-HPS is required from the
boilers on the
olefins production plant for the steam turbines, saving fuels for the boilers
and reducing
corresponding CO2 emissions. The MPS stream 605 is fed into the SMR as the
steam feed.
The LPS stream 627, at a flow rate of 165.7 tph, is supplied to the CO2
recovery unit 615 to
provide heat needed to regenerate the amine.
FIG. 7
[0090] FIG. 7 schematically illustrates an inventive waste heat recovery
process/system 701
of this disclosure. A natural gas feed stream 703 at a flow rate of 83.6 tph
an MPS stream 705
having a temperature of 378 C, an absolute pressure of 1,600 kPa, and a flow
rate of 238.9 tph
are fed into an Hz-rich fuel gas production unit 707, which is similar to the
unit 407 in FIG. 4.
Unit 707 comprises an SMR in which the natural gas/steam mixture is heated to
an elevated
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Date Recue/Date Received 2022-12-07
temperature and reformed under syngas producing conditions to produce a
reformed stream
comprising H2, CO, and residual CH4, a WHRU cooling the reformed stream and
producing an
HPS steam 721 with a flow rate of 435.8 tph and an absolute pressure of about
4,300 kPa, a
shift reactor receiving the cooled reformed stream to convert a portion of the
CO in the cooled
reformed stream to CO2 and to produce a shifted stream, a steam abatement unit
for removing
H20 from the shifted stream to produce a crude gas mixture stream 713
comprising H2, CO2,
and CH4. Stream 713 is then fed into a CO2 recovery unit 715 using an amine
absorption/regeneration process, to produce a CO2 stream 717 and a Hz-rich
stream 719. A
split stream 709 of stream 719 is fed into the SMR, and combusted to heat the
SMR and produce
a flue gas having a low CO2 concentration. Another split stream 711 of stream
719 can be
supplied as fuel gas to other equipment where it can be combusted to provide
heating. The CO2
stream 717 can be optionally compressed, liquefied, conducted away, stored,
sequestered, or
utilized.
[0091] The HPS stream 721, with a flow rate of 435.8 tph, is fed into a steam
turbine 725,
where it expands to produce an MPS stream 705 having the temperature, pressure
and flow rate
described above, an LPS stream 727, and 30.1 MW of shaft power rotating about
shaft 729.
The shaft power, 11.5 MW (15,400 hp) higher compared to the process of FIG. 4,
can be used
to drive a generator or a major compressor such as a process gas compressor, a
propylene
refrigeration compressor, and/or an ethylene refrigeration compressor in an
olefins production
plant. As such, less Super-HPS is required from the boilers on the olefins
production plant for
the steam turbines, saving fuels for the boilers and reducing corresponding
CO2 emissions. The
MPS stream 705 is fed into the SMR as the steam feed. The LPS stream 527, at a
flow rate of
165.7 tph, is supplied to the CO2 recovery unit 715 to provide heat needed to
regenerate the
amine.
[0092] In addition to the energy savings described and illustrated above, we
have found that
significant capital investment savings may be realized by integrating a
reforming process with
the steam system of an olefins production plant.
[0093] An olefins production plant is generally equipped with a water
demineralization plant
to provide high quality water to the cracking furnace quench exchanger
systems, and to the
boilers and/or COGEN units associated with the plant. If a "stand-alone"
syngas producing unit
including an SMR and/or ATR is used to generate a syngas, a Hz-rich fuel gas
stream, or a high-
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Date Recue/Date Received 2022-12-07
purity hydrogen stream, then the syngas producing unit will have to be
equipped with its own
dedicated water demineralization plant. If a syngas producing unit is
integrated with the steam
system of an olefins production plant, not only does it reduce the boiler
firing required for the
olefins production plant, but the WHRU associated with the syngas producing
unit can draw
the high-quality boiler-feed water required from the olefins production
plant's water
demineralization plant.
[0094] Moreover, if a "stand-alone" hydrogen plant including a syngas
producing unit is used
to generate a syngas, or an H2-rich fuel gas stream, or a high-purity hydrogen
stream, then the
syngas producing unit will require its own dedicated "power island" comprising
a steam turbine
to expand the excess HP steam generated by the WHRU, electrical generator and,
if the steam
turbine operates on a condensing cycle, a surface condenser, cooling tower and
cooling water
circulation system. If a syngas producing unit is integrated with the olefins
production plant's
steam system, the steam generated in the WHRU can be expanded in the steam-
turbines in the
olefins production plant, thus enabling the investment of the "power island"
of the stand-alone
hydrogen plant to be saved.
[0095] This disclosure can further include the following non-limiting
embodiments:
[0096] Al. A 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 recovery unit ("WHRU")
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 stream has a pressure higher than a pressure of 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 steam
turbine to
produce shaft power and an expanded steam stream having a pressure equal to or
higher than
the steam feed, wherein the at least one steam turbine is located in a
hydrocarbon production
plant; and
(E) supplying at least a portion of the expanded steam stream as the steam
feed in step
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Date Recue/Date Received 2022-12-07
(A).
[0097] A2. The process of Al, wherein the syngas producing unit comprises a
steam-
methane-reformer ("SMR") and/or an autothermal reformer ("ATR").
[0098] A3. The process of A2, wherein:
the syngas producing unit comprises a SMR; and
the SMR comprises: a plurality of SMR burners where a SMR fuel combusts to
supply
thermal energy to the 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.
[0099] A4. The process of A3, wherein step (C) comprises:
heating the HPS stream generated in step (B) in the convection section of the
SMR
and/or an auxiliary furnace to obtain the SH-HPS stream, wherein the SH-HPS
stream obtained
in step (C) has at least one of the following: a temperature from 350 C to
550 C, and a pressure
from 4000 kPa to 14,000 kPa.
[0100] A5. The process of A2, wherein:
the syngas producing unit comprises an AYR;
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 fed;
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
1100 C; and an absolute pressure from 2,000 kPa to 5,000 kPa.
[0101] A6. The process of A5, wherein step (C) comprises:
heating the HPS stream generated in step (B) in an auxiliary furnace to obtain
the SH-
HPS stream, wherein the SH-HPS stream obtained in step (C) 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.
[0102] A7. The process of any of Al to A6, wherein the expanded steam stream
produced
in step (D) has at least one of the following: a temperature from 260 C to
405 C; and an
absolute pressure from 1,380 kPa to 4,500 kPa.
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Date Recue/Date Received 2022-12-07
[0103] A8. The process of any of Al to A7, wherein the shaft power produced in
step (D)
drives a compressor located in an olefins production plant including a steam
cracker therein
operated under steam cracking conditions to convert a steam cracker feed into
a steam cracker
effluent comprising olefins.
[0104] A9. The process of any of Al to A8, wherein in step (D), one stage of
the steam
turbine is used.
[0105] A10. The process of any of any of Al to A9, wherein the steam feed in
step (A) has
an absolute pressure of at least 1,700 kPa, and the SH-HPS stream obtained in
step (C) has a
temperature of at least 371 C and an absolute pressure of at least 4,000 kPa.
[0106] All. The process of any of Al to A10, wherein the steam feed in step
(A) has an
absolute pressure of at least 1700 kPa, and the SH-HPS stream obtained in step
(C) has a
temperature of at least 482 C and an absolute pressure of at least 10,000 Oa.
[0107] Al2. The process of All, wherein the steam feed in step (A) has an
absolute pressure
of at least 2,500 kPa.
[0108] A13. The process of any of Al to Al2, wherein step (D) comprises:
(D1) expanding the at least a portion of the SH-HPS stream in a first stage
steam turbine
to produce shaft power and an intermediate steam stream; and
(D2) expanding at least a portion of the intermediate steam stream in a second
stage
steam turbine to produce additional shaft power and the expanded steam stream.
[0109] A14. The process of any of Al to A13, wherein the SH-HPS stream
produced in step
(C) is supplied to a HPS header supplying steam to the steam turbine of step
(D).
[0110] A15. The process of any of Al to A14, wherein the SH-HPS stream
produced in step
(C) is a super-high-pressure steam ( "Super-HPS" ) stream having an absolute
pressure of
8,370 kPa, and the SH-HPS stream is supplied to a SUPER-HPS header supplying
steam to the
steam turbine of step (D).
[0111] A16. The process of A13, wherein the intermediate steam stream is
supplied to a HPS
header or a medium pressure steam ("MPS") header, depending on the pressure of
the
intermediate steam stream, supplying steam to the second stage steam turbine.
[0112] A17. The process of any of A13 to A16, wherein the first stage steam
turbine drives
a process gas compressor located in an olefins production plant having a steam
cracker therein.
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Date Recue/Date Received 2022-12-07
[0113] A18. The process of any of Al3 to A17, wherein the second stage steam
turbine drives
a process gas compressor, a refrigeration compressor, an air compressor,
and/or a pump located
in the olefins production plant.
[0114] A19. The process of A18, wherein the second stage steam turbine drives
a propylene
refrigeration compressor and/or an ethylene refrigeration compressor.
[0115] A20. A 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) heating the HPS stream to obtain a super-heated high-pressure steam ("SH-
HPS")
stream, wherein the SH-HPS 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 steam
turbine to
produce shaft power and an expanded steam stream having a pressure equal to or
higher than
the steam feed, wherein the at least one steam turbine is located in an
olefins production plant,
and the at least steam turbine drives a process gas compressor located in the
olefins production
plant; and
(E) supplying at least a portion of the expanded steam stream as the steam
feed in step
(A).
[0116] A21. The process of A20, wherein step (D) comprises:
(D1) expanding the at least a portion of the SH-HPS stream in a first stage
steam turbine
to produce shaft power that drives the processor gas compressor and an
intermediate steam
stream; and
(D2) expanding at least a portion of the intermediate steam stream in a second
stage
steam turbine to produce additional shaft power and the expanded stream.
[0117] A22. The process of A20 or A21, wherein the second stage steam turbine
drives a
process gas compressor, or a refrigeration compressor, located in the olefins
production plant.
[0118] A23. The process of A22, wherein the second stage steam turbine drives
a propylene
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Date Recue/Date Received 2022-12-07
refrigeration compressor and/or an ethylene refrigeration compressor.
[0119] 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.
[0120] 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 2022-12-07
