Patent Description:
This disclosure relates to hydrocarbon reforming processes such as natural gas reforming processes for producing syngas and/or H<NUM>-rich fuel gas. In particular, this disclosure relates to hydrocarbon reforming processes integrated with an olefins production plant.

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 lightweight 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 C1-C4 hydrocarbons including ethylene and propylene. The process gas stream is then compressed to a higher pressure, cooled to a very low temperature in a chill chain, and separated in distillation columns to recover, among others, an ethylene product stream and a propylene product stream. Steam turbines are typically utilized in the olefins production plant. Superheated steam streams are generated to supply the steam turbines.

Syngas, a mixture comprising primarily H<NUM> and CO, optionally CO<NUM>, and optionally CH<NUM>, 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 H<NUM>, 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 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 CO<NUM> and H<NUM> and to produce a shifted stream comprising H<NUM>, CO, CO<NUM>, and H<NUM>O. Upon steam abatement, a second syngas comprising H<NUM>, CO, and CO<NUM> can be produced. Upon CO<NUM> recovery from the second syngas, a third syngas comprising H<NUM> and CO may be produced. If the third syngas comprises a low concentration of CO, the third syngas is a H<NUM>-rich gas suitable as a fuel gas stream. An H<NUM>-rich gas may be further purified to produce H<NUM> product with various levels of purity by using, e.g., a pressure-swing unit. <CIT> discloses a process for steam reforming of a hydrocarbon gas feed stream wherein waste heat is recovered from a secondary reformer effluent gas and from primary reforming combustion products by (i) heating a high pressure saturated steam in a first steam superheating zone by indirect heat exchange with at least a portion of said secondary reformer effluent gas to form a first superheated steam stream; and (ii) further heating said first superheated steam in a second steam superheating zone by indirect heat exchange with at least a portion of said primary reformer hot combustion gases to form a second superheated steam stream. <CIT> discloses a process for the production of carbon dioxide in concentrated form and electricity from a hydrocarbon feedstock.

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.

A process for producing syngas and/or an H<NUM>-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 CO<NUM> emission from the olefins production plant compared to running the olefins production plant separately.

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 H<NUM>, 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 a hydrocarbon production plant, wherein the hydrocarbon production plant is an olefins production plant and the shaft power produced in step (D) drives an equipment 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).

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. Any reference to the "invention" may refer to one or more, but not necessarily all, of the inventions defined by the claims.

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.

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.

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.

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.

The term "hydrocarbon" means (i) any compound consisting of hydrogen and carbon atoms or (ii) any mixture of two or more such compounds in (i). The term "Cn hydrocarbon," where n is a positive integer, means (i) any hydrocarbon compound comprising carbon atom(s) in its molecule at the total number of n, or (ii) any mixture of two or more such hydrocarbon compounds in (i). Thus, a C2 hydrocarbon can be ethane, ethylene, acetylene, or mixtures of at least two of these compounds at any proportion. A "Cm to Cn hydrocarbon" or "Cm-Cn hydrocarbon," where m and n are positive integers and m < n, means any of Cm, Cm+<NUM>, Cm+<NUM>,. , Cn-<NUM>, 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).

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 <NPL>.

"High-pressure steam" and "HPS" are used interchangeably to mean a steam having an absolute pressure of at least <NUM> kilopascal ("kPa"). "Super-high-pressure steam" and "Super-HPS" are used interchangeably to mean a steam having an absolute pressure of at least <NUM>,<NUM> 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 <NUM> kPa but less than <NUM>,<NUM> kPa. "Low-pressure steam" and "LPS" are used interchangeably to mean a steam having an absolute pressure of at least <NUM> kPa but less than <NUM> kPa.

"Consisting essentially of" means comprising ≥ <NUM> mol%, preferably ≥ <NUM> mol%, preferably ≥ <NUM> mol%, preferably ≥ <NUM> mol%, preferably ≥ <NUM> mol%; preferably <NUM> mol%, of a given material or compound, in a stream or mixture, based on the total moles of molecules in the stream or mixture.

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.

A first aspect of this disclosure relates to a hydrocarbon reforming process 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 H<NUM>, 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 hydrocarbon production plant is an olefins production plant and the shaft power produced in step (D) drives an equipment located in the olefines production plant; and (E) supplying at least a portion of the expanded steam stream as the steam feed in step (A).

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 H<NUM>, CO, and steam. The hydrocarbon feed can consist essentially of C1-C4 hydrocarbons (preferably saturated), preferably consists essentially of C1-C3 hydrocarbons (preferably saturated), preferably consists essentially of C1-C2 hydrocarbons (preferably saturated), and preferably consists essentially of CH<NUM>. The hydrocarbon feed and the steam feed may be combined to form a joint stream before being fed into the syngas producing unit. Alternatively, they may be fed into the syngas producing unit as separate streams, in which they admix with each other to form a mixture. The feed stream(s) can be pre-heated by, e.g., a furnace, a heat exchanger, and the like, before being fed into the syngas producing unit. The syngas producing unit can comprise a pre-reformer first receiving the feed stream(s), especially if the hydrocarbon feed comprises significant amount of C2+ hydrocarbons. In a pre-reformer, the hydrocarbon feed/steam feed mixture contacts a pre-reforming catalyst under conditions such that the C2+ hydrocarbons are preferentially converted into CH<NUM>. 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., <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>, and an absolute pressure from e.g., <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. The steam feed may have a temperature from, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or even __450_ °C, and an absolute pressure from e.g., <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. Preferably, the steam feed is a superheated steam.

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:
<CHM>.

The syngas producing condition can include a temperature of, e.g., from <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, to <NUM>, or even <NUM>, and an absolute pressure of, e.g., from <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa, in the reforming reactor, depending on the type of the reforming reactor and the syngas producing conditions. A lower pressure in the reformed stream, and hence a lower pressure in the reforming reactor, is conducive to a higher conversion of CH<NUM> in reforming reactor and hence a lower residual CH<NUM> concentration in the reformed stream. The reformed stream exiting the reforming reactor therefore comprises CO, H<NUM>, residual CH<NUM> and H<NUM>O, and optionally CO<NUM> 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 <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, to <NUM>, or even <NUM>, and an absolute pressure of, e.g., from <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa, depending on the type of the reforming reactor and the syngas producing conditions.

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 <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, or even <NUM>, and an absolute pressure of, e.g., from <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. To achieve a high CH<NUM> conversion in the SMR, and a low CH<NUM> concentration in the H<NUM>-rich stream produced from the process, the syngas producing conditions in the SMR preferably includes an absolute pressure of ≤ <NUM>,<NUM> kPa (<NUM> psig), more preferably ≤ <NUM>,<NUM> kPa (<NUM> psig). Description of an SMR can be found in, e.g., The International Energy Agency Greenhouse Gas R&D Program ("IEAGHG"), "Techno-Economic Evaluation of SMR Based Standalone (Merchant) Plant with CCS", February <NUM>; and IEAGHG, "Reference data and supporting literature Reviews for SMR based Hydrogen production with CCS", <NUM>-TR3, March <NUM>, the contents of which are incorporated herein in their entirety.

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 O<NUM> 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 <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>,<NUM>, <NUM>, to <NUM>,<NUM>, <NUM>,<NUM>, or even <NUM>,<NUM>, and an absolute pressure of, e.g., from <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. Commercially available ATRs, such as the Syncor™ ATR available from Haldor Topsoe, having an address at Haldor Topsøes Allé <NUM>, DK-<NUM>, Kgs. Lyngby, Denmark ("Topsoe"), may be used in the process of this disclosure.

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.

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., <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>. The cooled reformed stream can have a pressure substantially the same as the reformed stream exiting the reforming reactor. The WHRU can include, e.g., one or more heat exchanger and one or more steam drum in fluid communication with the heat exchanger. The steam drum supplies a water stream to the heat exchanger, where it is heated and can be then returned to the steam drum, where steam is separated from liquid phase water. The HPS stream can have an absolute pressure from, e.g., <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. In certain embodiments, the HPS stream is preferably a Super-HPS stream. The thus produced HPS stream is a saturated steam stream.

To make the HPS stream more useful, it is further heated in step (C) to produce a superheated HPS ("SH-HPS") stream in, e.g., a furnace. In case the syngas producing unit comprises an SMR having a convection section as described above, the saturated HPS stream may be advantageously superheated in the convection section of the SMR and/or in an auxiliary furnace. In case the syngas producing unit comprises one or more ATR but no SMR, the saturated HPS stream can be superheated in an auxiliary furnace. The auxiliary furnace can include one or more burners combusting a fuel gas stream to supply the needed thermal energy as is known to one skilled in the art. The SH-HPS stream can have one of both of: (i) a temperature from, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>; and (ii) an absolute pressure from, e.g., e.g., <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. Preferably the SH-HPS stream has a temperature of at least <NUM> and the steam feed in step (A) has an absolute pressure of at least <NUM> 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 is then 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 <NUM> and an absolute pressure of at least <NUM>,<NUM> kPa, and the steam feed has an absolute pressure of at least <NUM>,<NUM> kPa (e.g., at least <NUM>,<NUM> kPa). In a preferred embodiment, the SH-HPS stream may be supplied to an HPS header located in an industrial plant, such as an olefins production plant, supplying HPS to suitable equipment consuming SH-HPS. In another embodiment, the SH-HPS stream may be also a Super-HPS stream, and supplied to a Super-HPS header located in an industrial plant, such as an olefins production plant, supplying Super-HPS to suitable equipment consuming superheated Super-HPS.

The steam turbine(s) in step (D) are present in a hydrocarbon production plant wherein the hydrocarbon production plant is an olefins production plant. These plants typically include equipment consuming shaft power produced by steam turbines, e.g., gas compressors at various power ratings, pumps, electricity generators, and the like.

In 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., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>. The expanded steam stream has a pressure lower than the SH-HPS stream, which may range from, e.g., <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> 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.

Step (D) advantageously includes steam integration between a syngas producing unit and an olefins production plant which can include 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 (<NUM>) 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 <NUM> MW (<NUM>,<NUM> hp). This very high shaft power demand is a characteristic of olefins production plants, and differentiates them from most other petrochemical facilities. Typically the large compressors are driven by steam-turbines. The majority of the steam can be generated by the steam produced from cooling the steam cracker effluent as described above. If necessary, boilers are used to make-up the required steam volumes.

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 <NUM> BarG (<NUM> psig, or <NUM> 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).

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 <NUM> megawatt (<NUM> MW, or ≥ <NUM> MW, or ≥ <NUM> MW, or ≥ <NUM> MW) in the olefins production plant. In certain preferred embodiments, the SH-HPS stream obtained from step (C) (which may or not be a Super-HPS stream) may be supplied to a first stage steam turbine that drives a process gas compressor in an olefins production plant, and the expanded steam stream from the first stage steam turbine, which may be an SH-HPS stream or an MPS stream, may be supplied to a second stage steam turbine producing a second expanded steam stream and shaft power driving another 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.

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.

The cooled reformed stream obtained in step (B) of the reforming process as described above comprises H<NUM>, 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 H<NUM>. 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 CO<NUM> and H<NUM>, followed by steam abatement to obtain a second syngas comprising CO, H<NUM>, and CO<NUM>. One may further recover the CO<NUM> from the second syngas to produce a third syngas consisting essentially of CO, H<NUM>, 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., ≤ <NUM> mol%, ≤ <NUM> mol%, ≤ <NUM> mol%, ≤ <NUM> mol%, ≤ <NUM> mol%, ≤ <NUM> mol%, ≤ <NUM> mol%, based on the total moles of molecules in the third syngas, in which case the third syngas is an H<NUM>-rich gas. Such H<NUM>-rich gas can be advantageously used as a fuel gas, the combustion of which can produce a flue gas having appreciably lower CO<NUM> emission than combustion of natural gas.

A particularly advantageous process for producing H<NUM>-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 H<NUM>, 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 CO<NUM> 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 CO<NUM> concentration than the cooled first shifted stream; (VI) abating steam present in the second shifted stream to produce a crude gas mixture stream comprising CO<NUM> and H<NUM>; (VII) recovering at least a portion of the CO<NUM> present in the crude gas mixture stream to produce a CO<NUM> stream and a H<NUM>-rich stream, wherein the H<NUM>-rich stream comprises H<NUM> at a concentration of at least <NUM> mol%, based on the total moles of molecules in the H<NUM>-rich stream; and (VIII) combusting a portion of the H<NUM>-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 H<NUM>-rich stream, preferably using a process including steps (I) to (VII) above, may be called an H<NUM>-rich fuel gas production plant in this disclosure.

Steps (I) and (II) are identical with steps (A) and (B) of the reforming process described above.

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 temperature shift catalysts available from, e.g., Topsoe. The forward reaction of the following preferentially occur in the first shift reactor:
<CHM>.

As such, the first shifted stream has a lower CO concentration and a higher CO<NUM> concentration than the cooled reformed stream. The forward reaction of (R-<NUM>) 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., <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>. The first shifted stream can have an absolute pressure substantially the same as the cooled reformed stream.

While a single stage of shift reactor may convert sufficient amount of CO in the cooled reformed stream to CO<NUM> 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 CO<NUM>, and eventually to produce a H<NUM>-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 CO<NUM> and additional amount of H<NUM> 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 separated in the steam drum can be further superheated. The cooled first shifted stream can have a temperature from, e.g., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>, and a pressure substantially the same as the first shifted stream.

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:
<CHM>.

As such, the second shifted stream has a lower CO concentration and a higher CO<NUM> concentration than the cooled first shifted stream. The forward reaction of (R-<NUM>) 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., <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, to <NUM>, <NUM>, <NUM>, <NUM>, or even <NUM>. The second shifted stream can have an absolute pressure substantially the same as the cooled first shifted stream.

The second shifted stream comprises H<NUM>, CO<NUM>, CO, steam, and optionally CH<NUM>. In step (VI), steam is then abated from it by cooling and separation. Similar to step (IV) of cooling the first shifted stream, such cooling of the second shifted stream can be effected by one or more heat exchangers using one or more cooling streams having a temperature lower than the second shifted stream. In one preferred embodiment, the second shifted stream can be cooled by the hydrocarbon stream or a split stream thereof to be fed into the syngas producing unit. Alternatively or additionally, the first shifted stream can be cooled by a boiler water feed stream to produce a heated boiler water stream, a steam stream, and/or a water/steam mixture stream. The thus heated boiler water stream can be heated in a boiler to produce steam at various pressure. The thus heated boiler water stream or steam stream can be further heated by another process stream in another heat exchanger to produce steam. In one preferred embodiment, the heated boiler water stream and/or steam stream can be fed into the steam drum of the WHRU extracting heat from the reformed stream as described above, where 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.

The crude gas mixture stream thus consists essentially of CO<NUM>, H<NUM>, optionally CH<NUM> at various amounts, and steam and CO as minor components. The crude gas mixture stream can have an absolute pressure from, e.g., <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. In step (VII), one can recover a portion of the CO<NUM> therein to produce a CO<NUM> stream and a H<NUM>-rich stream. Any suitable CO<NUM> 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 CO<NUM> 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 CO<NUM> recovery equipment can be much smaller than otherwise required to recover CO<NUM> from a gas mixture at atmospheric pressure.

The CO<NUM> stream preferably comprises CO<NUM> at a molar concentration of from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>%, based on the total moles of molecules in the CO<NUM> stream. The CO<NUM> stream can comprise at least one and preferably all of, on a molar basis: (i) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>% of CO; (ii) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>% of H<NUM>O; and (iii) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>% of CH<NUM>. The CO<NUM> stream can have an absolute pressure from, e.g., <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa, depending on the CO<NUM> recovery process and equipment used. In a preferred embodiment, where an amine absorption/regeneration CO<NUM> recovery unit is utilized, the CO<NUM> may have an absolute pressure from e.g., <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, to <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, or even <NUM> kPa. The CO<NUM> 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 CO<NUM> stream, upon optional compression, can be conducted away in a CO<NUM> pipeline. In another embodiment, the CO<NUM> stream, upon optional compression and/or liquefaction, can be injected and stored in a geological formation. In yet another embodiment, the CO<NUM> stream, upon optional compression and/or liquefaction, can be used in extracting hydrocarbons present in a geological formation. Another exemplary use of the CO<NUM> stream is in food applications.

The H<NUM>-rich stream can have an absolute pressure from, e.g., <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, to <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, <NUM>,<NUM> kPa, or even <NUM>,<NUM> kPa. The H<NUM>-rich stream preferably comprises H<NUM> at a molar concentration of from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, or even <NUM>%, based on the total moles of molecules in the H<NUM>-rich stream. The H<NUM>-rich stream can comprise at least one and preferably all of, on a molar basis: (i) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>%, of CO; (ii) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>%, of CO<NUM>; and (iii) e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or even <NUM>% of CH<NUM>. One specific example of a H<NUM>-rich stream that may be produced from the process of this disclosure has the following molar composition: <NUM>% of CO<NUM>; <NUM>% of CO; <NUM>% of H<NUM>; <NUM>% of N<NUM>; <NUM>% of CH<NUM>; and <NUM>% of H<NUM>O.

Where an even higher purity H<NUM> stream is desired, a portion of the H<NUM>-rich stream can be further purified by using processes and technologies known to one skilled in the art, e.g., pressure-swing-separation.

Preferably, however, the H<NUM>-rich stream, notwithstanding the optional low concentrations of CO, CO<NUM>, and CH<NUM>, 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 concentrations of CO, CO<NUM>, and CH<NUM> therein compared to conventional fuel gases such as natural gas, the flue gas stream produced from combusting the H<NUM>-rich stream can comprise CO<NUM> at a considerably reduced concentration, resulting in appreciably lower CO<NUM> emission to the atmosphere. Thus, the flue gas stream can comprise CO<NUM> at a molar concentration from, e.g., <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%, preferably ≤ <NUM>%, preferably ≤ <NUM>%, preferably ≤ <NUM>%, based on the total moles of CO<NUM> and H<NUM>O in the flue gas stream. The combustion may be in the presence of, e.g., air, O<NUM>-enhanced air, high-purity O<NUM>, and the like, depending on the specific application.

For use as a fuel gas stream, the H<NUM>-rich stream may preferably has an absolute pressure of ≤ <NUM>,<NUM> kPa (<NUM> psig), preferably ≤ <NUM> kPa (<NUM> psig). To achieve such low pressure of the H<NUM>-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 ≤ <NUM>,<NUM> kPa (<NUM> psig), preferably ≤ <NUM>,<NUM> kPa (<NUM> psig). As mentioned above, a lower pressure in the reforming reactor results in a higher CH<NUM> conversion in the reforming reactor, and hence a low residual CH<NUM> concentration in the H<NUM>-rich stream.

Preferably, the H<NUM>-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 H<NUM>-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 H<NUM>-rich stream is supplied as at least a portion, preferably a majority, preferably the entirety, of the fuel gas to such burners. Where the syngas producing unit includes an SMR comprising one or more SMR burners combusting a SMR fuel, it is highly desirable to supply a portion of the H<NUM>-rich stream as at least a portion, preferably a majority, preferably the entirety, of the SMR fuel. Where the H<NUM>-rich stream production process/system uses an additional boiler or auxiliary furnace combusting a fuel gas, it is desirable supply a portion of the H<NUM>-rich stream as at least a portion, preferably a majority, preferably the entirety, of the fuel gas. By combusting the H<NUM>-rich stream and capturing the CO<NUM> stream, the H<NUM>-rich stream production process/system of this disclosure can reach an appreciably reduced level of CO<NUM> emission to the atmosphere than conventional H<NUM> production processes combusting natural gas.

Compared to existing syngas and/or H<NUM>-rich fuel gas producing processes, especially those combusting a hydrocarbon-containing fuel, the H<NUM>-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 CO<NUM> 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 CO<NUM> emission if the CO<NUM> stream is captured, stored, sequestered, and/or utilized.

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> schematically illustrates processes/systems <NUM> including an SMR for producing a H<NUM>-rich fuel stream. As shown, a hydrocarbon feed stream <NUM> (e.g., a natural gas stream comprising primarily CH<NUM>), which may contain CH<NUM>, C2+ hydrocarbons at various concentrations, and sulfur-containing compounds at various concentrations, is first fed into an optional sulfur removal unit <NUM> to produce a sulfur-abated stream <NUM>, 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 <NUM> is combined with an HPS stream <NUM> to form a hydrocarbon/steam mixture stream <NUM>. Upon optional preheating via, e.g., a heat exchanger or a furnace (not shown), stream <NUM> can be then fed into a pre-reformer <NUM> 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 <NUM> comprising methane and steam. Stream <NUM> is then fed into a tube 120a in the upper section <NUM>, sometimes called convection section, of an SMR <NUM>, where it is heated. SMR <NUM> comprises a lower section <NUM>, sometimes called radiant section, housing one or more tube 120b which is in fluid communication with tube 120a receiving the stream <NUM> 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 <NUM> comprises one or more burners <NUM> in the radiant section <NUM>, where a SMR fuel combusts to supply energy to the radiant section <NUM> and then the convection section <NUM> of SMR <NUM>. 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.

A reforming catalyst is loaded in tube(s) 120b in the radiant section <NUM>. Due to the proximity to the burner(s) <NUM>, 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:
<CHM>.

In addition, various amounts of CO<NUM> may be produced in tube(s) 120b. Thus, a reformed stream <NUM> comprising CO, H<NUM>, residual CH<NUM>, residual H<NUM>O and optionally various amount of CO<NUM> exits the outlet of tube(s) 120b from the SMR at a temperature of e.g., from <NUM> to <NUM> and an absolute pressure from, e.g., <NUM> kPa to <NUM>,<NUM> kPa. Stream <NUM> is then cooled at a waste heat recovery unit ("WHRU") including a waste heat boiler ("WHB") <NUM> and a steam drum <NUM> to produce a cooled reformed stream <NUM> and to generate an HPS stream <NUM>. As shown, a water stream <NUM> flows from steam drum <NUM> to WHB <NUM>, and a steam-water mixture stream <NUM> flows from WHB <NUM> to steam drum <NUM>.

Stream <NUM>, preferentially a saturated steam stream, is then heated in the convection section <NUM> of SMR <NUM> to produce a super-heated, high-pressure steam ("SP-HP") steam stream <NUM>, which is fed into a steam header and supplied to any suitable equipment or process step. For example, as shown and described above, a split stream <NUM> of stream <NUM> can be combined with the sulfur-abated hydrocarbon feed stream <NUM> to form a combined stream <NUM>, which is then fed into the pre-reformer <NUM>. A split stream <NUM> of stream <NUM> is fed into a steam turbine <NUM>, where it is expanded to produce an exhaust steam stream <NUM> and shaft power. The shaft power can be transferred, via shaft <NUM>, to any suitable equipment <NUM> to produce useful mechanical work. One example of equipment <NUM> is an electricity generator, which converts the mechanical work into electrical energy transmissible to any suitable local or distant electrical equipment. Exhaust steam stream <NUM> can have various residual pressure and temperature suitable for, e.g., driving additional steam turbines, heating other equipment and/or streams, and the like.

As shown in <FIG>, the cooled reformed stream <NUM>, comprising CO, H<NUM>, H<NUM>O, and optionally CO<NUM>, is then fed into a first shift reactor <NUM>. 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 <NUM> 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:
<CHM>.

Thus, a first shifted stream <NUM> comprising CO at a lower concentration than stream <NUM> and CO<NUM> at a higher concentration than stream <NUM> exits the first shift reactor <NUM>. Because the forward reaction above is exothermic, stream <NUM> has a higher temperature than stream <NUM> assuming the first shift reactor <NUM> is an adiabatic reactor.

The first shifted stream <NUM> can then be further cooled down at heat exchanger <NUM> by any suitable stream having a temperature lower than stream <NUM>. As shown in <FIG>, in a preferred embodiment, a boiler feed water stream <NUM>, supplied from a boiler feed water treatment unit <NUM>, is used to cool down stream <NUM>. The thus heated boiler feed water stream <NUM> exiting the heat exchanger <NUM> can be supplied to steam drum <NUM> and at least partly supplied to the WHB <NUM>, to produce high-pressure steam stream <NUM> as described earlier, or to any other suitable steam generator. Alternatively or additionally (not shown), the hydrocarbon feed stream <NUM>, or a portion thereof, may be heated by stream <NUM> at heat exchanger <NUM> or another heat exchanger upstream or downstream of heat exchanger <NUM>.

The cooled first shifted stream <NUM> exiting heat exchanger <NUM>, comprising CO, H<NUM>, H<NUM>O, and CO<NUM>, is then fed into a second shift reactor <NUM>. 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 <NUM>. Due to the lower temperature, the second shift reactor <NUM> 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:
<CHM>.

Thus, a second shifted stream <NUM> comprising CO at a lower concentration than stream <NUM> and CO<NUM> at a higher concentration than stream <NUM> exits the second shift reactor <NUM>. Because the forward reaction above is exothermic, stream <NUM> has a higher temperature than stream <NUM> assuming the second shift reactor <NUM> is an adiabatic reactor.

The second shifted stream <NUM> can then be further cooled down at heat exchanger <NUM> by any suitable stream having a temperature lower than stream <NUM>. In a preferred embodiment, a boiler feed water stream (not shown) supplied from a boiler feed water treatment unit (e.g., unit <NUM>) can be advantageously used to cool down stream <NUM>. The thus heated boiler feed water stream exiting the heat exchanger <NUM> can be supplied (not shown) to steam drum <NUM> and at least partly supplied to the WHB <NUM>, to produce high-pressure steam stream <NUM> as described earlier, or to any other suitable steam generator. Alternatively or additionally (not shown), the hydrocarbon feed stream <NUM>, or a portion thereof, may be heated by stream <NUM> at heat exchanger <NUM> or another heat exchanger upstream or downstream of heat exchanger <NUM>.

The cooled stream <NUM> exiting heat exchanger <NUM> can be further cooled at heat exchanger <NUM> by any suitable cooling medium having a lower temperature than stream <NUM>, 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 <NUM> is condensed to liquid water in stream <NUM>, which can be fed into a separator <NUM> to obtain a condensate stream <NUM> and a vapor stream <NUM>. The steam-abated stream <NUM>, a crude gas mixture, comprises primarily H<NUM> and CO<NUM>, and optionally minor amount of residual CH<NUM> and CO.

Stream <NUM> can then be supplied into a CO<NUM> recovery unit <NUM> to produce a CO<NUM> stream <NUM> and an H<NUM>-rich stream <NUM>. Any suitable CO<NUM> recovery unit known in the art may be used. A preferred CO<NUM> recovery unit is an amine absorption and regeneration unit, where the crude gas mixture stream <NUM> contacts a counter-current stream of amine which absorbs the CO<NUM>, which is subsequently released from the amine upon heating ("regeneration"). The CO<NUM> stream <NUM> can be supplied to a CO<NUM> pipeline and conducted away. The CO<NUM> stream <NUM> can be compressed, liquefied, stored, sequestered, or utilized in manners known to one skilled in the art.

The H<NUM>-rich stream <NUM> can advantageously comprise H<NUM> at a molar concentration from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, based on the total moles of molecules in stream <NUM>. In addition to H<NUM>, stream <NUM> may comprise: (i) CH<NUM> at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%; (ii) CO at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, or <NUM>%; and (iii) CO<NUM> at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%. Stream <NUM> can be advantageously used as a fuel gas for residential, office, and/or industrial heating, preferably industrial heating. Due to the high concentration of H<NUM> and low concentration of carbon-containing molecules therein, the combustion of stream <NUM> in the presence of an oxidant such as air, oxygen, and the like, can produce a flue gas stream comprising CO<NUM> at a low concentration. In certain embodiments, the flue gas stream can comprises CO<NUM> at a molar concentration based on the total moles of H<NUM>O and CO<NUM> in the flue gas stream of no greater than <NUM>% (e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM> mol%, or <NUM>%). The flue gas stream can be advantageously exhausted into the atmosphere without the need to separate and capture CO<NUM> therefrom.

In a preferred embodiment, as shown in <FIG>, a split stream <NUM> of stream <NUM> can be supplied to the SMR <NUM>, where it is combusted in burner(s) <NUM> to supply thermal energy to the SMR <NUM> heating the lower radiant section <NUM> and tube(s) 120b therein and the convection section <NUM> and tube 120a therein. The flue gas stream <NUM> exiting the SMR <NUM> comprises CO<NUM> at a low concentration, and therefore can be exhausted into the atmosphere without the need to separate and capture CO<NUM> therefrom.

<FIG> schematically illustrates processes/systems <NUM> including an ATR for producing a H<NUM>-rich fuel stream. As shown, a hydrocarbon feed stream <NUM> (e.g., a natural gas stream comprising primarily CH<NUM>), which may contain CH<NUM>, C2+ hydrocarbons at various concentrations, and sulfur-containing compounds at various concentrations, is first fed into an optional sulfur removal unit <NUM> to produce a sulfur-abated stream <NUM>, 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 <NUM> a heated stream <NUM> is produced. Stream <NUM> is then combined with an HPS stream <NUM> to form a hydrocarbon/steam mixture stream <NUM>. Upon optional preheating via, e.g., a heat exchanger or a furnace (not shown), stream <NUM> can be then fed into a pre-reformer <NUM> 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 <NUM> comprising methane and steam. Upon optional heating in furnace <NUM>, stream <NUM> becomes a heated stream <NUM>, which is then fed into an ATR <NUM>, an O<NUM> stream <NUM>, which may be produced by air separation, is also fed into ATR <NUM>.

A forming catalyst is loaded in ATR <NUM>. On contacting the reforming catalyst, the forward reaction of the following preferentially occurs under syngas producing conditions:
<CHM>.

In addition, various amounts of CO<NUM> may be produced in the ATR. Thus, a reformed stream <NUM> comprising CO, H<NUM>, residual H<NUM>O, optionally residual CH<NUM> at various concentrations, and optionally various amount of CO<NUM> exits ATR <NUM> at a temperature of e.g., from <NUM> to <NUM> and an absolute pressure from <NUM> kPa to <NUM>,<NUM> kPa. Stream <NUM> is then cooled at a waste heat recovery unit ("WHRU") including a waste heat boiler ("WHB") <NUM> and a steam drum <NUM> to produce a cooled reformed stream <NUM> and to generate an HPS stream <NUM>. As shown, a water stream <NUM> flows from steam drum <NUM> to WHB <NUM>, and a steam-water stream <NUM> flows from WHB <NUM> to steam drum <NUM>.

Stream <NUM>, preferentially a saturated steam stream, is then heated in an auxiliary furnace <NUM> to produce a super-heated, high-pressure steam ("SH-HPS") stream <NUM>, which is fed into a steam header and supplied to any suitable equipment or process step. Furnace <NUM> may be the same furnace as furnace <NUM> or a separate furnace. For example, as shown and described above, a split stream <NUM> of stream <NUM> can be combined with the sulfur-abated hydrocarbon feed stream <NUM> to form a combined stream <NUM>, which is then fed into the pre-reformer <NUM>. Split stream <NUM> of stream <NUM> isfed into a steam turbine <NUM>, where it is expanded to produce an exhaust steam stream <NUM> and shaft power. The shaft power can be transferred, via shaft <NUM>, to any suitable equipment <NUM> to produce useful mechanical work. One example of equipment <NUM> is an electricity generator, which converts the mechanical work into electrical energy transmissible to any suitable local or distant electrical equipment. Exhaust steam stream <NUM> can have various residual pressure and temperature suitable for, e.g., driving additional steam turbines, heating other equipment and/or streams, and the like.

The first shifted stream <NUM> can then be further cooled down at heat exchanger <NUM> by any suitable stream having a temperature lower than stream <NUM>. As shown in <FIG>, in a preferred embodiment, a boiler feed water stream <NUM>, supplied from a boiler feed water treatment unit <NUM>, can be used to cool down stream <NUM>. The thus heated boiler feed water stream <NUM> exiting the heat exchanger <NUM> can be supplied to steam drum <NUM> and at least partly subsequently supplied to the WHB <NUM>, to produce high-pressure steam stream <NUM> as described earlier, or to any other suitable steam generator. Alternatively or additionally (not shown), the hydrocarbon feed stream <NUM>, or a portion thereof, may be heated by stream <NUM> at heat exchanger <NUM> or another heat exchanger upstream or downstream of heat exchanger <NUM>.

The cooled stream <NUM> exiting heat exchanger <NUM> can be further cooled at heat exchanger <NUM> by any suitable cooling medium having a lower temperature than stream <NUM>, 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 <NUM> is condensed to liquid water in stream <NUM>, which can be fed into a separator <NUM> to obtain a condensate stream <NUM> and a vapor stream <NUM>. The steam-abated stream <NUM>, a crude gas mixture stream, comprises primarily H<NUM> and CO<NUM>, and optionally minor amount of residual CH<NUM> and CO.

The H<NUM>-rich stream <NUM> can advantageously comprise H<NUM> at a molar concentration from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, based on the total moles of molecules in stream <NUM>. In addition to H<NUM>, stream <NUM> may comprise: (i) CH<NUM> at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%; (ii) CO at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, or <NUM>%; and (iii) CO<NUM> at a molar concentration thereof based on the total moles of molecules in stream <NUM>, from, e.g., <NUM>%, <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, <NUM>%, or <NUM>%. Stream <NUM> can be advantageously used as a fuel gas for residential, office, and/or industrial heating. Due to the high concentration of H<NUM> and low concentration of carbon-containing molecules therein, the combustion of stream <NUM> in the presence of an oxidant such as air, oxygen, and the like, can produce a flue gas stream comprising CO<NUM> at a low concentration. In certain embodiments, the flue gas stream can comprises CO<NUM> at a molar concentration based on the total moles of H<NUM>O and CO<NUM> in the flue gas stream of no greater than <NUM>% (e.g., from <NUM>%, <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM>%, <NUM>%, to <NUM>%, <NUM> mol%, or <NUM>%). The flue gas stream can be advantageously exhausted into the atmosphere without the need to separate and capture CO<NUM> therefrom.

In a preferred embodiment, as shown in <FIG>, a split stream <NUM> of stream <NUM> (which is a split stream of stream <NUM>) can be supplied to furnace <NUM>, where it is combusted to preheat the de-sulfured hydrocarbon stream <NUM>, and a split stream <NUM> of stream <NUM> can be supplied to furnace <NUM>, where it is combusted to superheat steam stream <NUM>. The flue gas streams <NUM> and <NUM> exiting furnaces <NUM> and <NUM> comprise CO<NUM> at a low concentration, and therefore can be exhausted into the atmosphere without the need to separate and capture CO<NUM> therefrom.

<FIG> schematically illustrates an inventive process/system <NUM> with advantageous steam integration between a syngas or H<NUM>-rich fuel gas production unit and an olefins production plant including a stream cracker furnace. An SH-HPS stream (preferably a Super-HPS stream) <NUM> is generated from the WHRU of a syngas and/or H<NUM>-rich fuel gas production process <NUM> as described above. One or more SH-HPS stream(s) (preferably Super-HPS stream(s)) <NUM> are produced from one or more steam cracker furnace(s) <NUM>. One or more SH-HPS stream(s) (preferably Super-HPS stream(s)) <NUM>, if needed, are produced from one or more auxiliary steam boiler(s) <NUM>. Streams <NUM>, <NUM>, and <NUM> 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>, one or more HPS (preferably Super-HPS) stream(s) <NUM>, one or more HPS (preferably Super-HPS) stream(s) <NUM>, and one or more HPS (preferably Super-HPS) stream(s) <NUM> are supplied to one or more steam turbine(s) <NUM>, one or more steam turbine(s) <NUM>, and one or more steam turbine(s) <NUM>, respectively. Steam turbine(s) <NUM> can drive one or more process gas compressor(s). Steam turbine(s) <NUM> can drive one or more propylene refrigeration compressors. Steam turbine(s) <NUM> can drive one or more ethylene refrigeration compressors. From steam turbine(s) <NUM>, one or more HPS stream(s) <NUM> may be exhausted. Stream(s) <NUM> can be used to provide process heat, e.g., to a stream <NUM> in the olefins production plant or other facilities, or supplied to a steam turbine <NUM> receiving an HPS stream and exhausting a MPS stream, or supplied to a steam turbine <NUM> 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) <NUM>, one or more condensable stream(s) <NUM> may be exhausted, which can be condensed at condenser(s) <NUM> to produced one or more condensed water stream(s) <NUM>. From steam turbine(s) <NUM>, one or more MPS stream(s) <NUM> may be exhausted. Stream(s) <NUM> can be used to provide process heat, e.g., to a stream <NUM> in the olefins production plant or other facilities, or supplied to a steam turbine <NUM> 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) <NUM>, one or more condensable stream(s) <NUM> may be exhausted, which are then condensed at condenser(s) <NUM> to produced one or more condensed water stream(s) <NUM>. From steam turbine(s) <NUM>, one or more LPS stream(s) <NUM> may be exhausted. Stream(s) <NUM> can be used to provide process heat, e.g., to a stream <NUM> in the olefins production plant or other facilities. From steam turbine(s) <NUM>, one or more condensable stream(s) <NUM> may be exhausted, which are then condensed at condenser(s) <NUM> to produced one or more condensed water stream(s) <NUM>. Condensed water streams <NUM>, <NUM>, and <NUM> may be combined and processed together at location <NUM>, which can be subsequently reused in the facility. Without stream <NUM>, to satisfy the steam consumption needs of the various steam turbines driving the various compressors, pumps, generators, and process heating, boiler(s) <NUM> are required, which consume considerable amount of fuel and may produce considerable amount of CO<NUM> emission if a hydrocarbon fuel is used. With stream <NUM> supplied from a syngas and/or H<NUM>-rich fuel gas production unit <NUM> integrated into the process/system, to satisfy the steam consumption needs of the same steam turbines and process heating, boiler(s) <NUM> is required at a reduced size, or may be eliminated entirely, resulting in reduced fuel consumption in and reduced CO<NUM> emission from the olefins production plant.

<FIG> schematically illustrates a comparative SMR waste heat recovery process/system <NUM> in the prior art. A natural gas feed stream <NUM> at a flow rate of <NUM> tons per hour ("tph") and a steam stream <NUM> having a temperature of <NUM>, an absolute pressure of <NUM>,<NUM> kPa, and a flow rate of <NUM> tph are fed into an H<NUM>-rich fuel gas production unit <NUM>. Unit <NUM> 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 H<NUM>, CO, and residual CH<NUM>, a waste-heat recovery unit ("WHRU") cooling the reformed stream and producing an HPS stream <NUM> with a flow rate of <NUM> tph and an absolute pressure of <NUM>,<NUM> kPa and temperature of <NUM>, a shift reactor receiving the cooled reformed stream to convert a portion of the CO in the cooled reformed stream to CO<NUM> and to produce a shifted stream, a steam abatement unit for removing H<NUM>O from the shifted stream to produce a crude gas mixture stream <NUM> comprising H<NUM>, CO<NUM>, and CH<NUM>. Stream <NUM> is then fed into a CO<NUM> recovery unit <NUM> using an amine absorption/regeneration process, to produce a CO<NUM> stream <NUM> and a H<NUM>-rich stream <NUM>. A split stream <NUM> of stream <NUM> is fed into the SMR and combusted to heat the SMR and produce a flue gas having a low CO<NUM> concentration. Another split stream <NUM> of stream <NUM> can be supplied as fuel gas to other equipment where it can be combusted to provide heating. The CO<NUM> stream <NUM> can be optionally compressed, liquefied, conducted away, stored, sequestered, or utilized.

A split stream <NUM> of HPS stream <NUM>, with a flow rate of <NUM> tph, is fed into the SMR of unit <NUM>. Another split stream <NUM> of stream <NUM>, with a flow rate of <NUM> tph, is supplied to a steam turbine <NUM> having an isentropic efficiency of <NUM>%, where it expands to produce <NUM> megawatt ("MW") of shaft power, which can be used to drive a generator, and an LPS stream at a flow rate of <NUM> tph. The generator is sometimes called a "power island" in a SMR hydrogen plant. The LPS stream can be supplied to the CO<NUM> recovery unit <NUM> to provide heat needed to regenerate the amine.

<FIG> schematically illustrates an inventive waste heat recovery process/system <NUM> of this disclosure. A natural gas feed stream <NUM> at a flow rate of <NUM> tph and a steam stream <NUM> having a temperature of <NUM>, an absolute pressure of <NUM>,<NUM> kPa, and a flow rate of <NUM> tph are fed into an H<NUM>-rich fuel gas production unit <NUM>, which is similar to the unit <NUM> in <FIG>. Unit <NUM> 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 H<NUM>, CO, and residual CH<NUM>, a WHRU cooling the reformed stream and producing an Super-HPS stream <NUM> subsequently superheated to <NUM> with a flow rate of <NUM> tph and an absolute pressure of <NUM>,<NUM> kPa, a shift reactor receiving the cooled reformed stream to convert a portion of the CO in the cooled reformed stream to CO<NUM> and to produce a shifted stream, a steam abatement unit for removing H<NUM>O from the shifted stream to produce a crude gas mixture stream <NUM> comprising H<NUM>, CO<NUM>, and CH<NUM>. Stream <NUM> is then fed into a CO<NUM> recovery unit <NUM> using an amine absorption/regeneration process, to produce a CO<NUM> stream <NUM> and a H<NUM>-rich stream <NUM>. A split stream <NUM> of stream <NUM> is fed into the SMR, and combusted to heat the SMR and produce a flue gas having a low CO<NUM> concentration. Another split stream <NUM> of stream <NUM> can be supplied as fuel gas to other equipment where it can be combusted to provide heating. The CO<NUM> stream <NUM> can be optionally compressed, liquefied, conducted away, stored, sequestered, or utilized.

The superheated Super-HPS stream <NUM>, with a flow rate of <NUM> tph, is fed into a steam turbine <NUM> having an isentropic efficiency of <NUM>%, where it expands to produce an HPS stream <NUM> having the temperature and flow rate as described above, an LPS stream <NUM>, and <NUM> MW of shaft power rotating about shaft <NUM>, an increase of <NUM> MW (<NUM>,<NUM> hp) over the arrangement of <FIG> 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 <NUM> 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 CO<NUM> emissions. The HPS stream <NUM> is fed into the SMR as the steam feed. The LPS stream <NUM>, at a flow rate of <NUM> tph, can be supplied to the CO<NUM> recovery unit <NUM> to provide heat needed to regenerate the amine.

<FIG> schematically illustrates an inventive waste heat recovery process/system <NUM> of this disclosure. A natural gas feed stream <NUM> at a flow rate of <NUM> tph and an MPS stream <NUM> having a temperature of <NUM>, an absolute pressure of <NUM>,<NUM> kPa, and a flow rate of <NUM> tph are fed into an H<NUM>-rich fuel gas production unit <NUM>, which is similar to the unit <NUM> in <FIG>. Unit <NUM> comprises an SMR operated at a lower pressure than the SMR in the process of <FIG> to produce a reformed stream at a lower pressure than in the process of <FIG> to increase CH<NUM> conversion, a WHRU cooling the reformed stream and producing an Super-HPS stream <NUM> at <NUM>,<NUM> kPa absolute pressure, subsequently superheated to <NUM> with a flow rate of <NUM> tph and an absolute pressure of about <NUM>,<NUM> kPa, a shift reactor receiving the cooled reformed stream to convert a portion of the CO in the cooled reformed stream to CO<NUM> and to produce a shifted stream, a steam abatement unit for removing H<NUM>O from the shifted stream to produce a crude gas mixture stream <NUM> comprising H<NUM>, CO<NUM>, and CH<NUM>. Stream <NUM> is then fed into a CO<NUM> recovery unit <NUM> using an amine absorption/regeneration process, to produce a CO<NUM> stream <NUM> and a H<NUM>-rich stream <NUM>. A split stream <NUM> of stream <NUM> is fed into the SMR, and combusted to heat the SMR and produce a flue gas having a low CO<NUM> concentration. Another split stream <NUM> of stream <NUM> can be supplied as fuel gas to other equipment where it can be combusted to provide heating. The CO<NUM> stream <NUM> can be optionally compressed, liquefied, conducted away, stored, sequestered, or utilized.

The Super-HPS stream <NUM>, with a flow rate of <NUM> tph, is fed into a steam turbine <NUM>, where it expands to produce an MPS stream <NUM> having the temperature and pressure and flow rate described above, an LPS stream <NUM>, and <NUM> MW of shaft power rotating about shaft <NUM>. The shaft power, <NUM> MW (<NUM>,<NUM> hp) higher compared to the process of <FIG>, 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 CO<NUM> emissions. The MPS stream <NUM> is fed into the SMR as the steam feed. The LPS stream <NUM>, at a flow rate of <NUM> tph, is supplied to the CO<NUM> recovery unit <NUM> to provide heat needed to regenerate the amine.

<FIG> schematically illustrates an inventive waste heat recovery process/system <NUM> of this disclosure. A natural gas feed stream <NUM> at a flow rate of <NUM> tph an MPS stream <NUM> having a temperature of <NUM>, an absolute pressure of <NUM>,<NUM> kPa, and a flow rate of <NUM> tph are fed into an H<NUM>-rich fuel gas production unit <NUM>, which is similar to the unit <NUM> in <FIG>. Unit <NUM> 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 H<NUM>, CO, and residual CH<NUM>, a WHRU cooling the reformed stream and producing an HPS stream <NUM> with a flow rate of <NUM> tph and an absolute pressure of about <NUM>,<NUM> kPa, a shift reactor receiving the cooled reformed stream to convert a portion of the CO in the cooled reformed stream to CO<NUM> and to produce a shifted stream, a steam abatement unit for removing H<NUM>O from the shifted stream to produce a crude gas mixture stream <NUM> comprising H<NUM>, CO<NUM>, and CH<NUM>. Stream <NUM> is then fed into a CO<NUM> recovery unit <NUM> using an amine absorption/regeneration process, to produce a CO<NUM> stream <NUM> and a H<NUM>-rich stream <NUM>. A split stream <NUM> of stream <NUM> is fed into the SMR, and combusted to heat the SMR and produce a flue gas having a low CO<NUM> concentration. Another split stream <NUM> of stream <NUM> can be supplied as fuel gas to other equipment where it can be combusted to provide heating. The CO<NUM> stream <NUM> can be optionally compressed, liquefied, conducted away, stored, sequestered, or utilized.

The HPS stream <NUM>, with a flow rate of <NUM> tph, is fed into a steam turbine <NUM>, where it expands to produce an MPS stream <NUM> having the temperature, pressure and flow rate described above, an LPS stream <NUM>, and <NUM> MW of shaft power rotating about shaft <NUM>. The shaft power, <NUM> MW (<NUM>,<NUM> hp) higher compared to the process of <FIG>, 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 CO<NUM> emissions. The MPS stream <NUM> is fed into the SMR as the steam feed. The LPS stream <NUM>, at a flow rate of <NUM> tph, is supplied to the CO<NUM> recovery unit <NUM> to provide heat needed to regenerate the amine.

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.

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 H<NUM>-rich fuel gas stream, or a high-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.

Moreover, if a "stand-alone" hydrogen plant including a syngas producing unit is used to generate a syngas, or an H<NUM>-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.

Claim 1:
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 H<NUM>, 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, wherein the hydrocarbon production plant is an olefins production plant and the shaft power produced in step (D) drives an equipment 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).