EP4638827A1 - Use of co2-rich gas as a sweeping gas in a chemical plant - Google Patents

Use of co2-rich gas as a sweeping gas in a chemical plant

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Publication number
EP4638827A1
EP4638827A1 EP23828751.0A EP23828751A EP4638827A1 EP 4638827 A1 EP4638827 A1 EP 4638827A1 EP 23828751 A EP23828751 A EP 23828751A EP 4638827 A1 EP4638827 A1 EP 4638827A1
Authority
EP
European Patent Office
Prior art keywords
stream
rich
feed
oxygen
electrolysis
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP23828751.0A
Other languages
German (de)
French (fr)
Inventor
Steffen Spangsberg Christensen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Topsoe AS
Original Assignee
Haldor Topsoe AS
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Filing date
Publication date
Application filed by Haldor Topsoe AS filed Critical Haldor Topsoe AS
Publication of EP4638827A1 publication Critical patent/EP4638827A1/en
Pending legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/02—Hydrogen or oxygen
    • C25B1/04—Hydrogen or oxygen by electrolysis of water
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/32—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air
    • C01B3/34—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/32—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air
    • C01B3/34—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents
    • C01B3/38—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents using catalysts
    • C01B3/382—Processes with two or more reaction steps, of which at least one is catalytic, e.g. steam reforming and partial oxidation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen; Reversible storage of hydrogen
    • C01B3/02—Production of hydrogen; Production of gaseous mixtures containing hydrogen
    • C01B3/32—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air
    • C01B3/34—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents
    • C01B3/48—Production of hydrogen; Production of gaseous mixtures containing hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide or air by reaction of hydrocarbons with gasifying agents followed by reaction of water vapour with carbon monoxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B1/00—Electrolytic production of inorganic compounds or non-metals
    • C25B1/01—Products
    • C25B1/23—Carbon monoxide or syngas
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B15/00—Operating or servicing cells
    • C25B15/08—Supplying or removing reactants or electrolytes; Regeneration of electrolytes
    • C25B15/083—Separating products
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B3/00—Electrolytic production of organic compounds
    • C25B3/20—Processes
    • C25B3/25—Reduction
    • C25B3/26—Reduction of carbon dioxide
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
    • C25B9/00—Cells or assemblies of cells; Constructional parts of cells; Assemblies of constructional parts, e.g. electrode-diaphragm assemblies; Process-related cell features
    • C25B9/70—Assemblies comprising two or more cells

Definitions

  • a plant e.g. a syngas plant or hydrogen plant, or a combined syngas and hydrogen plant.
  • the plant comprises a reforming section, a CO 2 -removal section and a first electrolysis unit.
  • a first portion of a first CO 2 -rich stream outputted from the CO 2 -removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas for oxygen product gas.
  • Certain streams, downstream the first electrolysis unit are arranged to be fed to the reforming section as at least a portion of an oxygen-rich feed.
  • Various processes are also provided for the production of hydrogen and/or syngas in the plant.
  • An autothermal reformer is used to provide a synthesis gas (syngas) stream from a hydrocarbon-rich stream.
  • An ATR typically comprises a burner, a combustion chamber, and a catalyst bed contained within a refractory lined pressure shell.
  • ATR partial combustion of hydrocarbons by sub-stoichiometric amounts of oxygen is followed by steam reforming. ATRs therefore require a co-feed of oxygen for combustion in a burner.
  • This oxygen stream is typically provided by an air separation unit (ASU).
  • ASU air separation unit
  • Oxygen streams from industrial-scale electrolysis processes such as those which take place in a solid oxide electrolyzer cells (SOEC), is often considered as a waste product, and is simply vented to the atmosphere.
  • SOEC solid oxide electrolyzer cells
  • a so-called "sweeping gas” or “sweep gas” is typically employed.
  • the sweeping gas is passed into the anode-side of the electrolyser, where it mixes with the oxygen produced at the anode.
  • the resulting combined gas stream containing oxygen is then outputted from the electrolyser.
  • Use of a sweeping gas provides a combined gas stream at a pressure higher than that of the oxygen stream produced in the electrolyser, and can be used e.g.
  • Atmospheric air has typically been used as sweeping gas, and has the advantage of being readily-available.
  • atmospheric air can lead to a build-up of inert nitrogen, if recycled to other parts of a chemical plant (e.g. an ATR).
  • US8496908 describes a steam methane reforming process for producing a hydrogen product while capturing CO 2 from the process.
  • WO2021/156457 describes a method for supplying oxygen-enriched gas to an oxygenconsuming process.
  • the present invention requires CO 2 as a reagent in the oxygen-rich feed to the reforming section - not simply a by-product.
  • CO 2 is thus a carbon feedstock in the reforming reaction, to make best use of carbon. Excess CO 2 is removed downstream the reforming section and recycled.
  • a plant and process have been developed which reduce energy consumption and the cost of producing an O 2 -rich stream to an ATR.
  • the plant may be a hydrogen plant, a syngas plant, or a combined hydrogen and syngas plant.
  • the present invention relates to a plant, said plant comprising a combined feed of steam and hydrocarbons; a reforming section comprising an autothermal reformer, said reforming section being arranged to receive said combined feed and an oxygen-rich feed and provide a first syngas stream; a CO 2 -removal section, arranged to receive first syngas stream and provide a first hydrogen-rich stream and a first CO 2 -rich stream; a first electrolysis unit comprising an anode and a cathode; a first electrolysis feed to said first electrolysis unit; wherein said first electrolysis unit is arranged to electrolyse the first electrolysis feed into at least an oxygen product gas and a cathode product gas stream; and wherein at least a first portion of said first CO 2 -rich stream from the CO 2 -removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and
  • a process for the production of hydrogen and/or syngas in the plant of the invention comprising the steps of: providing a plant according to the invention; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream to the CO 2 -removal section, so as to provide a first hydrogen-rich stream and a first CC>2-rich stream; feeding the first electrolysis feed to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream; supplying at least a first portion of said first CO 2 -rich stream from the CO 2 - removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; optionally, where the plant comprises a first water-removal section and a CO 2 separation unit, o feeding at least
  • the present invention is based on the recognition that it is possible to use CO 2 recycled from a CO 2 -removal section placed downstream of the autothermal reformer as sweeping gas in the anode side of an electrolyser in order to sweep oxygen formed therein.
  • the present invention is further based on the recognition that when using CO 2 as a sweeping gas, purification of the combined oxygen and sweeping gas stream before use in the autothermal reformer may be avoided, since CO 2 unlike e.g. nitrogen of atmospheric air is not an undesired component in the autothermal reformer.
  • the present invention is further based on the recognition that the said recycling of CO 2 optimizes the carbon mass balance of the plant of the invention in that all carbon fed to the plant may be utilized to form a syngas product.
  • oxygen originating from the anode side of an electrolyser does not comprise any contaminants, such as argon, nitrogen and helium, which needs to be separated off before use in the autothermal reformer.
  • Fig. 1 illustrates a general layout of the plant.
  • Figs. 2A and 2B illustrate variations of a hydrogen plant
  • Fig. 3 illustrates a syngas plant
  • Fig. 4 illustrates a general layout of the plant, based on the layout of Figure 1.
  • any given percentages for gas content are % by volume.
  • synthesis gas (abbreviated to “syngas”) is meant to denote a gas comprising hydrogen, carbon monoxide, carbon dioxide, steam and small amounts of other gasses, such as argon, nitrogen, methane, etc.
  • sweeping gas means a gas supplied to the electrolysis unit for use as a carrier for carrying 02 out from the electrolysis unit, and the chemical components of the sweeping gas are not subjected to any chemical reaction or conversion during passage through the electrolysis unit.
  • a plant which comprises, in general terms: a combined feed of steam and hydrocarbons; a reforming section comprising an autothermal reformer; a CO 2 -removal section; a first electrolysis unit comprising an anode and a cathode; a first electrolysis feed to the first electrolysis unit; optionally, a first water-removal section and a C0 2 separation unit.
  • a combined feed of steam and hydrocarbons is provided.
  • the combined feed is typically provided by mixing a steam feed and a hydrocarbon feed.
  • the hydrocarbon feed may suitably be a feed of natural gas, LPG, naphtha and various hydrocarbon containing off-gasses from other plants/processes.
  • the hydrocarbon feed is suitably methane-rich, e.g. it comprises more than 90% methane, such as more than 95% methane, and preferably more than 98% methane.
  • the combined feed is fed to the reforming section - specifically to the ATR - where it is converted to a first syngas stream.
  • the reforming section comprises an autothermal reformer (ATR).
  • ATR autothermal reformer
  • the reforming section is arranged to receive the combined feed and an oxygen-rich feed and provide a first syngas stream.
  • An ATR typically comprises a burner, a combustion chamber, and a catalyst bed contained within a refractory lined pressure shell.
  • partial combustion of hydrocarbons by sub-stoichiometric amounts of oxygen is followed by steam reforming - i.e., the reverse of reaction (1) and (2) - of the partially combusted hydrocarbons in a fixed bed of steam reforming catalyst.
  • the gas is at or close to equilibrium at the outlet of the reactor with respect to steam reforming and water gas shift reactions. More details of ATR and a full description can be found in the art such as "Studies in Surface Science and Catalysis, Vol. 152,” Synthesis gas production for FT synthesis”; Chapter 4, p.258-352, 2004”"
  • the first syngas stream suitably has a composition as follows:
  • the oxygen-rich feed provides the required oxygen to the ATR burner.
  • the oxygen-rich feed suitably comprises more than 50% oxygen, such as more than 60% oxygen, preferably more than 90% oxygen and preferably more than 99% oxygen.
  • the oxygen-rich feed suitably comprises up to 50% CO 2 , such as up to 30% CO 2 , preferably up to 20% CO 2 , and preferably up to 10% CO 2 .
  • the oxygen-rich feed to the reforming section is generated by one or more other components of the plant, as set out below. Other components of this oxygen-rich feed may include H 2 O and CO 2 .
  • the reforming section may further comprise a prereformer, arranged upstream the autothermal reformer, and arranged to prereform the combined feed to form a pre-reformed combined feed, and arranged to feed the prereformed combined feed to the autothermal reformer.
  • a prereformer the higher hydrocarbons contained in the natural gas feed are converted into methane, thus reducing the formation of coke in the primary reformer.
  • the CO 2 -removal section is arranged to receive the first syngas stream and provide a first hydrogen-rich stream and a first CO 2 -rich stream.
  • Removal of CO 2 provides a hydrogen-rich stream with as a low CO 2 -content, such as below 2% 1%, preferably below 0.5%, more preferably below 0.1% on dry gas basis.
  • the CO2-rich stream typically comprises at least 99% (e.g. 99.8) dry% CO 2 and below 1 dry% (e.g. 0.2 dry%) H 2 .
  • the main impurity in the CO 2 -rich stream is H 2 .
  • Other impurities include Ar, CH 4 , CO, N 2 which may be present at (insignificant) ppm levels.
  • the CO 2 -removal section is located upstream a PSA unit, it is suitably a solvent-based unit such as an amine wash unit. If the CO 2 -removal section is located downstream a PSA unit it is suitably a cryogenic unit.
  • a first electrolysis feed is provided to the first electrolysis unit.
  • the first electrolysis unit is arranged to electrolyse the first electrolysis feed into at least an oxygen product gas and a cathode product gas stream.
  • the first electrolysis unit comprises an anode and a cathode.
  • the first electrolysis unit is one or more solid oxide electrolyzer cells (SOECs). SOEC design and construction is known e.g. from WO2013/164172, the contents of which are incorporated by reference.
  • the first electrolysis unit of the plant of the invention may be an alkaline eletrolyzer or a proton exchange membrane (PEM) electrolyser.
  • PEM proton exchange membrane
  • the first electrolysis feed may be a water-rich feed or a CO 2 -rich feed, depending on the desired outcome.
  • the first electrolysis feed is a water-rich feed and the first electrolysis unit is arranged to electrolyse the first electrolysis feed into oxygen as anode product gas and hydrogen as cathode product gas.
  • the first electrolysis feed is a CO 2 -rich feed and the first electrolysis unit is arranged to electrolyse the first electrolysis feed into oxygen as anode product gas and carbon monoxide as cathode product gas.
  • the first electrolysis feed may be a CO 2 -rich feed, and may additionally comprise water.
  • At least a first portion of the first CO 2 -rich stream from the CO 2 -removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas (also known as "flushing gas") for the oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit.
  • a sweeping gas also known as "flushing gas”
  • Use of CO 2 as sweeping gas in this manner reduces the build-up of inerts such as nitrogen, which would otherwise be present if atmospheric air were used as a sweeping gas.
  • the swept stream leaving the electrolysis plant will only contain 02 and CO2, typically 50% of each.
  • the sweeping gas can be used directly in the ATR burner or can be mixed with additional 02 e.g., from an air separating unit (ASU). Using this sweeping gas stream will reduce energy consumption and the cost of ASU.
  • the CO 2 may be recycled in the process and can be captured in a downstream CO 2 removal unit.
  • the CO 2 in the sweeping gas exiting SOEC can be removed, such as condensed out, to obtain a clean O 2 stream for the ATR burner and a clean CO 2 stream, which can be recycled back to the SOEC.
  • a portion of the combined gas stream from the first electrolysis unit maybe arranged to be fed (i.e. directly fed) to the reforming section as at least a portion of said oxygen-rich feed.
  • the plant may further comprise a first water-removal section and a CO 2 separation unit.
  • the first water-removal section and a CO 2 separation unit are arranged in series, to purify the combined gas stream.
  • the first water-removal section - if present - is arranged to receive at least a portion of the first combined gas stream from the first electrolysis unit and provide at least a first waterrich stream and a second combined gas stream.
  • the CO 2 separation unit - if present - is arranged to receive at least a portion of the second combined gas stream from the first water-removal section and provide at least a second CO 2 -rich stream and an oxygen-rich stream.
  • one or more oxygen-containing streams may be used as the oxygen-rich feed to the reforming section.
  • the plant comprises first water-removal section and CO 2 separation unit as specified, and that at least a portion of the oxygen-rich stream from the CO 2 separation unit, is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
  • the oxygen content of the oxygen-rich feed to the reforming section depends on the origin of the stream from which it is comprised. If the oxygen-rich feed is supplied from the first electrolysis unit (i.e. it is at least a portion of the combined gas stream from the first electrolysis unit) it comprises O 2 , CO 2 and water.
  • the oxygen-rich feed is supplied from the first water-removal section (i.e. it is at least a portion of the second combined gas stream from the first water-removal section) it may have a higher oxygen content than that outputted from the first electrolysis unit, the remainder of this stream being primarily CO 2 .
  • the oxygen-rich feed is supplied from the first water-removal section (i.e. it is at least a portion of the oxygen-rich stream from the CO 2 separation unit) it may have an oxygen content of more than 99%.
  • At least a portion of the first water-rich stream from the first water-removal section is provided as a portion of the first water-rich feed to the first electrolysis unit.
  • Additional oxygen feed may be supplied as at least a portion of the oxygen-rich feed, e.g. during startup.
  • a portion of the oxygen-rich feed may be provided from a different source, e.g., an ASU.
  • the plant of the invention may be a hydrogen plant, and may therefore further comprise a shift section arranged to receive the first syngas stream from the reforming section, and provide a shifted first syngas stream to the CO 2 -removal section. Hydrogen production is thus promoted.
  • the first electrolysis feed is a water-rich feed, and the first electrolysis unit is thus arranged to electrolyse the first electrolysis feed into oxygen product gas.
  • the cathode product gas stream being a hydrogen-rich product stream.
  • the hydrogen plant comprises a first water-removal section and a CO 2 separation unit, arranged as above. At least a portion of the oxygen-rich stream (from the CO 2 separation unit) is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
  • the first hydrogen-rich stream from the CO 2 -removal section may be provided from the hydrogen plant as a raw hydrogen stream.
  • the hydrogen plant may further comprise a pressure-swing absorption (PSA) unit, said PSA unit being arranged to receive the first hydrogen-rich stream from the CO 2 -removal section, and provide a purified hydrogen stream and a PSA off-gas stream.
  • PSA off-gas (mostly comprising H 2 and CH 4 ) may be used as feed or fuel elsewhere in the plant, or exported from the plant.
  • the PSA unit is located between shift section and the CO 2 -removal section.
  • the PSA unit is arranged to receive the shifted first syngas stream from the shift section and provide a purified hydrogen stream and a PSA offgas stream, and feed the PSA off-gas stream to the CO 2 -removal section.
  • the CO 2 removal section removes CO 2 from the PSA off-gas stream to a first CO 2 -rich stream (which is fed to the electrolysis section, as above) and a CO 2 removal section off-gas stream.
  • a condensate stream is also provided, comprising mostly water.
  • the off-gas stream from the CO 2 removal section may be used as feed for the reformer or as fuel for a fired heater, as required.
  • the hydrogen plant comprises a second water-removal section arranged to receive at least a first portion of the hydrogen-rich product stream from the first electrolysis unit and provide at least a second water-rich stream and a second purified hydrogen stream.
  • the second purified hydrogen stream can be outputted from the hydrogen plant, as a supplement to the first hydrogen-rich stream.
  • the second purified hydrogen stream may be passed to the PSA unit.
  • at least a second portion of the hydrogen-rich product stream from the first electrolysis unit may be arranged to be fed to the inlet of the PSA unit, typically in admixture with the first hydrogen-rich stream from the CO 2 -removal section.
  • the plant may be a syngas plant.
  • the first electrolysis feed is a waterrich feed
  • the first electrolysis unit is arranged to electrolyse the first electrolysis feed into a cathode product gas stream being a syngas product stream.
  • the oxygen-rich feed to the reforming section need not have a high oxygen content. Therefore, at least a portion of the combined gas stream from the first electrolysis unit is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
  • the first CC>2-rich stream from the CO 2 -removal section may have additional uses; namely, as feed to the first electrolysis unit.
  • the first electrolysis feed may comprise a second portion of the first CO 2 -rich stream from the CO 2 - removal section.
  • the CO 2 used as feed to the electrolysis unit may also be derived from the CO 2 separation unit.
  • the first electrolysis feed comprises at least a portion of the second CO 2 - rich stream from the CO 2 separation unit.
  • the syngas plant may further comprise a second water-removal section.
  • the second waterremoval section may be arranged to receive at least a portion of the first hydrogen-rich stream and provide at least a second water-rich stream and a second combined gas stream.
  • the plant may further comprise a second electrolysis unit.
  • the second electrolysis unit allows flexibility in terms of the input streams to the plant.
  • the second electrolysis unit may comprise one or more solid oxide electrolyzer cells (SOECs).
  • SOECs solid oxide electrolyzer cells
  • the second electrolysis unit of the plant of the invention may be an alkaline eletrolyzer or a proton exchange membrane (PEM) electrolyser.
  • PEM proton exchange membrane
  • a second portion of the first CO 2 -rich stream from the CO 2 -removal section may be arranged to be supplied as electrolysis feed to the second electrolysis unit.
  • the second electrolysis unit is arranged to electrolyse the second portion of the first CO 2 -rich stream into an oxygen product gas and a CO-containing stream.
  • a third portion of the first CC>2-rich stream from the CC>2-removal section is arranged to be supplied to the anode of the second electrolysis unit as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and oxygen from said second electrolysis unit.
  • a water feed may be arranged to be mixed with the second portion of the of the first CO 2 -rich stream, upstream the second electrolysis unit.
  • the co-electrolysis of water with the CO 2 -rich stream will produce H 2 .
  • the electrolysis product (CO-containing stream) will be a mixture of CO and H 2 which is a syngas that can be used for methanol production or other chemical production.
  • the second electrolysis unit allows H 2 production in the main line and the second electrolysis unit making syngas by CO 2 electrolysis. Likewise, a syngas production can take place in the main line and the second electrolysis unit could provide H 2 by water electrolysis.
  • the plant may comprise a second water-removal section arranged to receive at least a first portion of the hydrogen-rich product stream from said first electrolysis unit and provide at least a second water-rich stream and a second purified hydrogen stream.
  • This second purified hydrogen stream may be exported from the plant as hydrogen product, optionally together with the first hydrogen stream.
  • At least a portion of the second water-rich stream outputted from the second water-removal section is provided as a portion of the first water-rich feed to the first electrolysis unit.
  • the plant may further comprise a second water-removal section, the second water-removal section, being arranged to receive at least a portion of said first hydrogen-rich stream and provide at least a second water-rich stream and a second combined gas stream.
  • the invention also provides a number of processes in the plants described above.
  • a process for the production of hydrogen and/or syngas in the plant described herein comprises the steps of: providing a plant as described herein; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream to the CO 2 -removal section, so as to provide a first hydrogen-rich stream and a first CO 2 -rich stream; feeding the first electrolysis feed to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream; supplying at least a first portion of said first CO 2 -rich stream from the CO 2 - removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; optionally, where the plant comprises a first water-removal section and a CO 2 separation unit, o feeding at least a
  • a process for the production of hydrogen is also provided, in a hydrogen plant described herein.
  • This process comprises the steps of: providing a hydrogen plant according to the invention; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed , to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream from the reforming section to the shift section, so as to provide a shifted first syngas stream to the CO 2 -removal section, feeding the shifted first syngas stream to the CO 2 -removal section , so as to provide a first hydrogen-rich stream and a first CO 2 -rich stream; feeding the first electrolysis feed , being a water-rich feed, to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream being a hydrogen-rich product stream; supplying at least a first portion of said first CO 2 -rich stream from the CO 2 - removal section to the anode of the first electrolysis unit
  • a process for the production of syngas is also provided, in a syngas plant described herein.
  • This process comprises the steps of: providing a syngas plant as described herein; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream from the reforming section to the shift section, so as to provide a shifted first syngas stream to the CO 2 -removal section, feeding the shifted first syngas stream to the CO 2 -removal section, so as to provide a first hydrogen-rich stream and a first CO 2 -rich stream; feeding the first electrolysis feed, being a water-rich feed, to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream being a syngas product stream; supplying at least a first portion of said first CO 2 -rich stream from the CO 2 - removal section to the anode of the first electrolysis unit as
  • the process according to this embodiment may further comprising a step of feeding a second portion of said first CO 2 -rich stream from the CO 2 -removal section to the first electrolysis unit as at least a portion of the first electrolysis feed.
  • Fig. 1 illustrates a general layout of the plant (100).
  • Combined feed (3) of steam (2) and hydrocarbons (1) is fed to the reforming section (10) together with an oxygen-rich feed (4) so as to provide a first syngas stream (11).
  • the first syngas stream (11) is fed to the CO 2 - removal section (30), and a first hydrogen-rich stream (31) and a first CO 2 -rich stream (32) are provided.
  • First electrolysis feed (9), e.g. water or CO2, or a mixture thereof, is provided to the first electrolysis unit (40), where it is electrolysed into at least an oxygen product gas and a cathode product gas stream (45).
  • a first portion (32a) of the first CO 2 -rich stream (32) from the CO 2 -removal section (30) is supplied to the anode of the first electrolysis unit (40) as a sweeping gas for the oxygen product gas.
  • Another portion (32d) of the first CO 2 -rich stream (32) from the CO 2 -removal section (30) may be exported, as it may not be necessary that all of this stream is recycled through the electrolysis unit (40).
  • a first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40) is outputted from the first electrolysis unit (40).
  • Figure 1 also shows, a first water-removal section (50) and a CO 2 separation unit (60), both of which are optional.
  • the first water-removal section (50) is arranged to receive at least a portion (41a) of the first combined gas stream (41) from the first electrolysis unit (40) and provide at least a first water-rich stream (51) and a second combined gas stream (52).
  • the CO 2 separation unit (60) is arranged to receive at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) and provide at least a second CO 2 -rich stream (61) and an oxygen-rich stream (62).
  • one or more streams is/are arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
  • feeds are selected from: at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40), a second portion (52b) of said second combined gas stream (52), if present, and at least a portion of said oxygen-rich stream (62), if present.
  • Additional oxygen feed (6) may be supplied as at least a portion of the oxygen-rich feed, e.g. during startup.
  • a steam feed (5) may be supplied to the reforming section (10).
  • Figs. 2A and 2B illustrate variations of a hydrogen plant, based on the layout of Figure 1.
  • These figures comprise the same elements as Figure 1, with the addition of: shift section (20), PSA unit (70), which generates purified hydrogen stream (71) and a PSA off-gas stream (72), and second water-removal section (80), which provides a second water-rich stream (81) and a second purified hydrogen stream (82).
  • the PSA unit is located downstream the CC>2-removal section (30), while in figure 2B, the PSA unit is located upstream the CO 2 -removal section (30).
  • Purified hydrogen stream (71) is exported from the plant.
  • the first electrolysis feed (9) is a water-rich feed.
  • Fig. 3 illustrates a syngas plant, based on the layout of Figure 1.
  • Figure 3 comprises the same elements as Figure 1.
  • the first electrolysis feed (9) is a waterrich feed, which may comprise a portion of the first CO 2 -rich stream (32) from the CO 2 - removal section (30).
  • the cathode product gas stream (45) from the first electrolysis unit (40) is a syngas product stream (43), which is exported from the plant.
  • Fig. 4 illustrates a general layout of the plant, based on the layout of Figure 1.
  • This layout includes a second electrolysis unit (140).
  • a second portion (32b) of the first CO 2 -rich stream (32) from the CO 2 -removal section (30) is arranged to be supplied as electrolysis feed to the second electrolysis unit (140).
  • the second electrolysis unit (140) electrolyses the second portion (32b) of the first CO 2 -rich stream (32) into an oxygen product gas and a CO- containing stream (142).
  • a third portion (32c) of the first CO 2 -rich stream (32) from the CO 2 -removal section (30) is supplied to the anode of the second electrolysis unit (140) as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream (141) comprising carbon dioxide and oxygen from said second electrolysis unit (140).

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Abstract

A plant, e.g. a syngas plant or hydrogen plant, or a combined syngas and hydrogen plant is provided. The plant comprises a reforming section, a CO2-removal section and a first electrolysis unit. A first portion of a first CO2-rich stream outputted from the CO2-removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas for oxygen product gas. Certain streams, downstream the first electrolysis unit are arranged to be fed to the reforming section as at least a portion of an oxygen-rich feed. Various processes are also provided for the production of hydrogen and/or syngas in the plant.

Description

USE OF CO2-RICH GAS AS A SWEEPING GAS IN A CHEMICAL PLANT
TECHNICAL FIELD
A plant, e.g. a syngas plant or hydrogen plant, or a combined syngas and hydrogen plant is provided. The plant comprises a reforming section, a CO2-removal section and a first electrolysis unit. A first portion of a first CO2-rich stream outputted from the CO2-removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas for oxygen product gas. Certain streams, downstream the first electrolysis unit are arranged to be fed to the reforming section as at least a portion of an oxygen-rich feed. Various processes are also provided for the production of hydrogen and/or syngas in the plant.
BACKGROUND
There is increasing interest in the use of electrolysis in industrial chemical plants and processes, to produce gas streams such as oxygen or hydrogen, especially in view of environmental concerns, and the increasing opportunities for using electricity from renewable sources.
An autothermal reformer (ATR) is used to provide a synthesis gas (syngas) stream from a hydrocarbon-rich stream. An ATR typically comprises a burner, a combustion chamber, and a catalyst bed contained within a refractory lined pressure shell. In an ATR, partial combustion of hydrocarbons by sub-stoichiometric amounts of oxygen is followed by steam reforming. ATRs therefore require a co-feed of oxygen for combustion in a burner. This oxygen stream is typically provided by an air separation unit (ASU). Such ASUs are expensive
Oxygen streams from industrial-scale electrolysis processes, such as those which take place in a solid oxide electrolyzer cells (SOEC), is often considered as a waste product, and is simply vented to the atmosphere. If oxygen streams from such industrial-scale electrolysis processes are to be effectively used, a so-called "sweeping gas" or "sweep gas" is typically employed. The sweeping gas is passed into the anode-side of the electrolyser, where it mixes with the oxygen produced at the anode. The resulting combined gas stream containing oxygen is then outputted from the electrolyser. Use of a sweeping gas provides a combined gas stream at a pressure higher than that of the oxygen stream produced in the electrolyser, and can be used e.g. to adjust the chemical and physical composition of the oxygen stream, for a particular use. Atmospheric air has typically been used as sweeping gas, and has the advantage of being readily-available. However, the use of atmospheric air as sweeping gas can lead to a build-up of inert nitrogen, if recycled to other parts of a chemical plant (e.g. an ATR).
US8496908 describes a steam methane reforming process for producing a hydrogen product while capturing CO2 from the process.
WO2021/156457 describes a method for supplying oxygen-enriched gas to an oxygenconsuming process. In contrast, the present invention requires CO2 as a reagent in the oxygen-rich feed to the reforming section - not simply a by-product. CO2 is thus a carbon feedstock in the reforming reaction, to make best use of carbon. Excess CO2 is removed downstream the reforming section and recycled.
There remains a need for an energy-effective source of oxygen for an ATR in a chemical plant. There is also a need to make good use of waste streams in chemical plants. These, and other objects, are addressed by the present technology.
SUMMARY
A plant and process have been developed which reduce energy consumption and the cost of producing an O2-rich stream to an ATR. The plant may be a hydrogen plant, a syngas plant, or a combined hydrogen and syngas plant.
So, in a first aspect the present invention relates to a plant, said plant comprising a combined feed of steam and hydrocarbons; a reforming section comprising an autothermal reformer, said reforming section being arranged to receive said combined feed and an oxygen-rich feed and provide a first syngas stream; a CO2-removal section, arranged to receive first syngas stream and provide a first hydrogen-rich stream and a first CO2-rich stream; a first electrolysis unit comprising an anode and a cathode; a first electrolysis feed to said first electrolysis unit; wherein said first electrolysis unit is arranged to electrolyse the first electrolysis feed into at least an oxygen product gas and a cathode product gas stream; and wherein at least a first portion of said first CO2-rich stream from the CO2-removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; optionally, a first water-removal section and a CO2 separation unit, wherein the first water-removal section is arranged to receive at least a portion of said first combined gas stream from said first electrolysis unit and provide at least a first water-rich stream and a second combined gas stream; and wherein said CO2 separation unit is arranged to receive at least a portion of the second combined gas stream from the first water-removal section and provide at least a second CC>2-rich stream and an oxygen-rich stream; and wherein one or more streams selected from: o at least a portion of the combined gas stream from the first electrolysis unit, o a second portion of said second combined gas stream, if present, and o at least a portion of said oxygen-rich stream, if present, is/are arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
A process for the production of hydrogen and/or syngas in the plant of the invention is also provided, said process comprising the steps of: providing a plant according to the invention; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream to the CO2-removal section, so as to provide a first hydrogen-rich stream and a first CC>2-rich stream; feeding the first electrolysis feed to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream; supplying at least a first portion of said first CO2-rich stream from the CO2- removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; optionally, where the plant comprises a first water-removal section and a CO2 separation unit, o feeding at least a portion of said first combined gas stream from the first electrolysis unit to the first water-removal section so as to provide at least a first water-rich stream and a second combined gas stream; and o feeding at least a portion of the second combined gas stream from the first water-removal section to the CO2 separation unit and providing at least a second CO2-rich stream and an oxygen-rich stream; said process comprising the additional step of feeding one or more streams selected from: o at least a portion of the combined gas stream from the first electrolysis unit, o a second portion of said second combined gas stream, if present, and o at least a portion of said oxygen-rich stream, if present, to the reforming section as at least a portion of said oxygen-rich feed.
Further details of the technology are to be found in the accompanying figures, claims and description text.
The present invention is based on the recognition that it is possible to use CO2 recycled from a CO2-removal section placed downstream of the autothermal reformer as sweeping gas in the anode side of an electrolyser in order to sweep oxygen formed therein. The present invention is further based on the recognition that when using CO2 as a sweeping gas, purification of the combined oxygen and sweeping gas stream before use in the autothermal reformer may be avoided, since CO2 unlike e.g. nitrogen of atmospheric air is not an undesired component in the autothermal reformer. The present invention is further based on the recognition that the said recycling of CO2 optimizes the carbon mass balance of the plant of the invention in that all carbon fed to the plant may be utilized to form a syngas product.
Finally, as compared to using an oxygen feed for the autothermal reformer formed in an Air Separation Unit (ASU), oxygen originating from the anode side of an electrolyser does not comprise any contaminants, such as argon, nitrogen and helium, which needs to be separated off before use in the autothermal reformer.
LEGENDS
The following schematic figures are provided, in which: Fig. 1 illustrates a general layout of the plant.
Figs. 2A and 2B illustrate variations of a hydrogen plant
Fig. 3 illustrates a syngas plant.
Fig. 4 illustrates a general layout of the plant, based on the layout of Figure 1.
DETAILED DISCLOSURE
Unless otherwise specified, any given percentages for gas content are % by volume.
The term "synthesis gas" (abbreviated to "syngas") is meant to denote a gas comprising hydrogen, carbon monoxide, carbon dioxide, steam and small amounts of other gasses, such as argon, nitrogen, methane, etc.
The term "sweeping gas" means a gas supplied to the electrolysis unit for use as a carrier for carrying 02 out from the electrolysis unit, and the chemical components of the sweeping gas are not subjected to any chemical reaction or conversion during passage through the electrolysis unit.
A plant is provided, which comprises, in general terms: a combined feed of steam and hydrocarbons; a reforming section comprising an autothermal reformer; a CO2-removal section; a first electrolysis unit comprising an anode and a cathode; a first electrolysis feed to the first electrolysis unit; optionally, a first water-removal section and a C02 separation unit.
Combined feed
A combined feed of steam and hydrocarbons is provided. The combined feed is typically provided by mixing a steam feed and a hydrocarbon feed. The hydrocarbon feed may suitably be a feed of natural gas, LPG, naphtha and various hydrocarbon containing off-gasses from other plants/processes. The hydrocarbon feed is suitably methane-rich, e.g. it comprises more than 90% methane, such as more than 95% methane, and preferably more than 98% methane. The combined feed is fed to the reforming section - specifically to the ATR - where it is converted to a first syngas stream.
Reforming section
The reforming section comprises an autothermal reformer (ATR). The reforming section is arranged to receive the combined feed and an oxygen-rich feed and provide a first syngas stream.
An ATR typically comprises a burner, a combustion chamber, and a catalyst bed contained within a refractory lined pressure shell. In an ATR, partial combustion of hydrocarbons by sub-stoichiometric amounts of oxygen is followed by steam reforming - i.e., the reverse of reaction (1) and (2) - of the partially combusted hydrocarbons in a fixed bed of steam reforming catalyst.
CO (g) + 3H2 (g) CH4 (g) + H2O (g) (1)
CO2 (g) + 4H2 (g) CH4 (g) + 2H2O (g) (2)
Typically, the gas is at or close to equilibrium at the outlet of the reactor with respect to steam reforming and water gas shift reactions. More details of ATR and a full description can be found in the art such as "Studies in Surface Science and Catalysis, Vol. 152," Synthesis gas production for FT synthesis"; Chapter 4, p.258-352, 2004""
The first syngas stream suitably has a composition as follows:
- H2 65-75 dry%,
- CO 15-30 dry%,
- CO2 4-8 dry%,
- CH4 1.5-6 dry%
The oxygen-rich feed provides the required oxygen to the ATR burner. The oxygen-rich feed suitably comprises more than 50% oxygen, such as more than 60% oxygen, preferably more than 90% oxygen and preferably more than 99% oxygen.
The oxygen-rich feed suitably comprises up to 50% CO2, such as up to 30% CO2, preferably up to 20% CO2, and preferably up to 10% CO2. The oxygen-rich feed to the reforming section is generated by one or more other components of the plant, as set out below. Other components of this oxygen-rich feed may include H2O and CO2.
The reforming section may further comprise a prereformer, arranged upstream the autothermal reformer, and arranged to prereform the combined feed to form a pre-reformed combined feed, and arranged to feed the prereformed combined feed to the autothermal reformer. In the prereformer, the higher hydrocarbons contained in the natural gas feed are converted into methane, thus reducing the formation of coke in the primary reformer.
CO2-removal section
The CO2-removal section is arranged to receive the first syngas stream and provide a first hydrogen-rich stream and a first CO2-rich stream.
Removal of CO2 provides a hydrogen-rich stream with as a low CO2-content, such as below 2% 1%, preferably below 0.5%, more preferably below 0.1% on dry gas basis.
The CO2-rich stream typically comprises at least 99% (e.g. 99.8) dry% CO2 and below 1 dry% (e.g. 0.2 dry%) H2. The main impurity in the CO2-rich stream is H2. Other impurities include Ar, CH4, CO, N2 which may be present at (insignificant) ppm levels.
If the CO2-removal section is located upstream a PSA unit, it is suitably a solvent-based unit such as an amine wash unit. If the CO2-removal section is located downstream a PSA unit it is suitably a cryogenic unit.
First electrolysis unit
A first electrolysis feed is provided to the first electrolysis unit. The first electrolysis unit is arranged to electrolyse the first electrolysis feed into at least an oxygen product gas and a cathode product gas stream. The first electrolysis unit comprises an anode and a cathode. Preferably, the first electrolysis unit is one or more solid oxide electrolyzer cells (SOECs). SOEC design and construction is known e.g. from WO2013/164172, the contents of which are incorporated by reference. Alternatively, the first electrolysis unit of the plant of the invention may be an alkaline eletrolyzer or a proton exchange membrane (PEM) electrolyser.
The first electrolysis feed may be a water-rich feed or a CO2-rich feed, depending on the desired outcome. In one aspect, the first electrolysis feed is a water-rich feed and the first electrolysis unit is arranged to electrolyse the first electrolysis feed into oxygen as anode product gas and hydrogen as cathode product gas. In another aspect, the first electrolysis feed is a CO2-rich feed and the first electrolysis unit is arranged to electrolyse the first electrolysis feed into oxygen as anode product gas and carbon monoxide as cathode product gas. In a further aspect, the first electrolysis feed may be a CO2-rich feed, and may additionally comprise water.
At least a first portion of the first CO2-rich stream from the CO2-removal section is arranged to be supplied to the anode of the first electrolysis unit as a sweeping gas (also known as "flushing gas") for the oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit. Use of CO2 as sweeping gas in this manner reduces the build-up of inerts such as nitrogen, which would otherwise be present if atmospheric air were used as a sweeping gas.
When using CO2 as the sweeping gas, the swept stream leaving the electrolysis plant will only contain 02 and CO2, typically 50% of each. The sweeping gas can be used directly in the ATR burner or can be mixed with additional 02 e.g., from an air separating unit (ASU). Using this sweeping gas stream will reduce energy consumption and the cost of ASU. The CO2 may be recycled in the process and can be captured in a downstream CO2 removal unit. Alternatively, the CO2 in the sweeping gas exiting SOEC can be removed, such as condensed out, to obtain a clean O2 stream for the ATR burner and a clean CO2 stream, which can be recycled back to the SOEC.
A portion of the combined gas stream from the first electrolysis unit, maybe arranged to be fed (i.e. directly fed) to the reforming section as at least a portion of said oxygen-rich feed.
Alternatively, or additionally, at least a portion of this combined gas stream may be further purified, before being fed to the reforming section. In particular, the plant may further comprise a first water-removal section and a CO2 separation unit. The first water-removal section and a CO2 separation unit are arranged in series, to purify the combined gas stream. The first water-removal section - if present - is arranged to receive at least a portion of the first combined gas stream from the first electrolysis unit and provide at least a first waterrich stream and a second combined gas stream. The CO2 separation unit - if present - is arranged to receive at least a portion of the second combined gas stream from the first water-removal section and provide at least a second CO2-rich stream and an oxygen-rich stream.
As noted above, one or more oxygen-containing streams may be used as the oxygen-rich feed to the reforming section. In the present invention, one or more streams selected from: at least a portion of the combined gas stream from the first electrolysis unit, a second portion of said second combined gas stream, if present, and at least a portion of said oxygen-rich stream, if present, is/are arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
It is preferred that the plant comprises first water-removal section and CO2 separation unit as specified, and that at least a portion of the oxygen-rich stream from the CO2 separation unit, is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
The oxygen content of the oxygen-rich feed to the reforming section depends on the origin of the stream from which it is comprised. If the oxygen-rich feed is supplied from the first electrolysis unit (i.e. it is at least a portion of the combined gas stream from the first electrolysis unit) it comprises O2, CO2 and water.
If the oxygen-rich feed is supplied from the first water-removal section (i.e. it is at least a portion of the second combined gas stream from the first water-removal section) it may have a higher oxygen content than that outputted from the first electrolysis unit, the remainder of this stream being primarily CO2.
If the oxygen-rich feed is supplied from the first water-removal section (i.e. it is at least a portion of the oxygen-rich stream from the CO2 separation unit) it may have an oxygen content of more than 99%.
In one aspect, at least a portion of the first water-rich stream from the first water-removal section is provided as a portion of the first water-rich feed to the first electrolysis unit. Additional oxygen feed may be supplied as at least a portion of the oxygen-rich feed, e.g. during startup.
During e.g., startup, a portion of the oxygen-rich feed may be provided from a different source, e.g., an ASU.
Hydrogen plant
The plant of the invention may be a hydrogen plant, and may therefore further comprise a shift section arranged to receive the first syngas stream from the reforming section, and provide a shifted first syngas stream to the CO2-removal section. Hydrogen production is thus promoted.
In the hydrogen plant, the first electrolysis feed is a water-rich feed, and the first electrolysis unit is thus arranged to electrolyse the first electrolysis feed into oxygen product gas. The cathode product gas stream, being a hydrogen-rich product stream.
The hydrogen plant comprises a first water-removal section and a CO2 separation unit, arranged as above. At least a portion of the oxygen-rich stream (from the CO2 separation unit) is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
The first hydrogen-rich stream from the CO2-removal section may be provided from the hydrogen plant as a raw hydrogen stream. If required, the hydrogen plant may further comprise a pressure-swing absorption (PSA) unit, said PSA unit being arranged to receive the first hydrogen-rich stream from the CO2-removal section, and provide a purified hydrogen stream and a PSA off-gas stream. The PSA off-gas (mostly comprising H2 and CH4) may be used as feed or fuel elsewhere in the plant, or exported from the plant.
In an alternative arrangement, shown in figure 2B, the PSA unit is located between shift section and the CO2-removal section. The PSA unit is arranged to receive the shifted first syngas stream from the shift section and provide a purified hydrogen stream and a PSA offgas stream, and feed the PSA off-gas stream to the CO2-removal section. The CO2 removal section removes CO2 from the PSA off-gas stream to a first CO2-rich stream (which is fed to the electrolysis section, as above) and a CO2 removal section off-gas stream. A condensate stream is also provided, comprising mostly water. The off-gas stream from the CO2 removal section may be used as feed for the reformer or as fuel for a fired heater, as required.
In one aspect, the hydrogen plant comprises a second water-removal section arranged to receive at least a first portion of the hydrogen-rich product stream from the first electrolysis unit and provide at least a second water-rich stream and a second purified hydrogen stream. The second purified hydrogen stream can be outputted from the hydrogen plant, as a supplement to the first hydrogen-rich stream.
If further purification of the second purified hydrogen stream is required, it may be passed to the PSA unit. In other words, at least a second portion of the hydrogen-rich product stream from the first electrolysis unit may be arranged to be fed to the inlet of the PSA unit, typically in admixture with the first hydrogen-rich stream from the CO2-removal section. Syngas Plant
The plant may be a syngas plant. In this embodiment, the first electrolysis feed is a waterrich feed, and the first electrolysis unit is arranged to electrolyse the first electrolysis feed into a cathode product gas stream being a syngas product stream.
In this embodiment, the oxygen-rich feed to the reforming section need not have a high oxygen content. Therefore, at least a portion of the combined gas stream from the first electrolysis unit is arranged to be fed to the reforming section as at least a portion of said oxygen-rich feed.
In this embodiment, the first CC>2-rich stream from the CO2-removal section may have additional uses; namely, as feed to the first electrolysis unit. In other words, the first electrolysis feed may comprise a second portion of the first CO2-rich stream from the CO2- removal section.
The CO2 used as feed to the electrolysis unit may also be derived from the CO2 separation unit. In this case, the first electrolysis feed comprises at least a portion of the second CO2- rich stream from the CO2 separation unit.
The syngas plant may further comprise a second water-removal section. The second waterremoval section may be arranged to receive at least a portion of the first hydrogen-rich stream and provide at least a second water-rich stream and a second combined gas stream.
Second electrolysis unit
The plant (the hydrogen plant, or the syngas plant) may further comprise a second electrolysis unit. The second electrolysis unit allows flexibility in terms of the input streams to the plant. The second electrolysis unit may comprise one or more solid oxide electrolyzer cells (SOECs). Alternatively, the second electrolysis unit of the plant of the invention may be an alkaline eletrolyzer or a proton exchange membrane (PEM) electrolyser.
In this embodiment, a second portion of the first CO2-rich stream from the CO2-removal section may be arranged to be supplied as electrolysis feed to the second electrolysis unit. The second electrolysis unit is arranged to electrolyse the second portion of the first CO2-rich stream into an oxygen product gas and a CO-containing stream. A third portion of the first CC>2-rich stream from the CC>2-removal section is arranged to be supplied to the anode of the second electrolysis unit as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream comprising carbon dioxide and oxygen from said second electrolysis unit.
In this embodiment, a water feed may be arranged to be mixed with the second portion of the of the first CO2-rich stream, upstream the second electrolysis unit. The co-electrolysis of water with the CO2-rich stream will produce H2. So, the electrolysis product (CO-containing stream) will be a mixture of CO and H2 which is a syngas that can be used for methanol production or other chemical production.
The second electrolysis unit allows H2 production in the main line and the second electrolysis unit making syngas by CO2 electrolysis. Likewise, a syngas production can take place in the main line and the second electrolysis unit could provide H2 by water electrolysis.
Additional units
The plant may comprise a second water-removal section arranged to receive at least a first portion of the hydrogen-rich product stream from said first electrolysis unit and provide at least a second water-rich stream and a second purified hydrogen stream. This second purified hydrogen stream may be exported from the plant as hydrogen product, optionally together with the first hydrogen stream.
In one aspect, at least a portion of the second water-rich stream outputted from the second water-removal section is provided as a portion of the first water-rich feed to the first electrolysis unit.
The plant may further comprise a second water-removal section, the second water-removal section, being arranged to receive at least a portion of said first hydrogen-rich stream and provide at least a second water-rich stream and a second combined gas stream.
Processes
The invention also provides a number of processes in the plants described above.
A process is provided for the production of hydrogen and/or syngas in the plant described herein. This process comprises the steps of: providing a plant as described herein; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream to the CO2-removal section, so as to provide a first hydrogen-rich stream and a first CO2-rich stream; feeding the first electrolysis feed to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream; supplying at least a first portion of said first CO2-rich stream from the CO2- removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; optionally, where the plant comprises a first water-removal section and a CO2 separation unit, o feeding at least a portion of said first combined gas stream from the first electrolysis unit to the first water-removal section so as to provide at least a first water-rich stream and a second combined gas stream; and o feeding at least a portion of the second combined gas stream from the first water-removal section to the CO2 separation unit and providing at least a second CO2-rich stream and an oxygen-rich stream; said process comprising the additional step of feeding one or more streams selected from: o at least a portion of the combined gas stream from the first electrolysis unit, o a second portion of said second combined gas stream, if present, and o at least a portion of said oxygen-rich stream, if present, to the reforming section as at least a portion of said oxygen-rich feed.
A process for the production of hydrogen is also provided, in a hydrogen plant described herein. This process comprises the steps of: providing a hydrogen plant according to the invention; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed , to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream from the reforming section to the shift section, so as to provide a shifted first syngas stream to the CO2-removal section, feeding the shifted first syngas stream to the CO2-removal section , so as to provide a first hydrogen-rich stream and a first CO2-rich stream; feeding the first electrolysis feed , being a water-rich feed, to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream being a hydrogen-rich product stream; supplying at least a first portion of said first CO2-rich stream from the CO2- removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; feeding at least a portion of said first combined gas stream from the first electrolysis unit to the first water-removal section so as to provide at least a first water-rich stream and a second combined gas stream; and feeding at least a portion of the second combined gas stream from the first waterremoval section to the CO2 separation unit and providing at least a second CO2- rich stream and an oxygen-rich stream; said process comprising the additional step of feeding at least a portion of said oxygen-rich stream to the reforming section as at least a portion of said oxygenrich feed.
A process for the production of syngas is also provided, in a syngas plant described herein. This process comprises the steps of: providing a syngas plant as described herein; feeding the combined feed of steam and hydrocarbons, and the oxygen-rich feed, to the reforming section comprising an autothermal reformer, so as to provide a first syngas stream; feeding the first syngas stream from the reforming section to the shift section, so as to provide a shifted first syngas stream to the CO2-removal section, feeding the shifted first syngas stream to the CO2-removal section, so as to provide a first hydrogen-rich stream and a first CO2-rich stream; feeding the first electrolysis feed, being a water-rich feed, to the first electrolysis unit and electrolysing it into at least an oxygen product gas and a cathode product gas stream being a syngas product stream; supplying at least a first portion of said first CO2-rich stream from the CO2- removal section to the anode of the first electrolysis unit as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream comprising carbon dioxide and oxygen from said electrolysis unit; feeding at least a portion of said first combined gas stream from the first electrolysis unit to the reforming section as at least a portion of said oxygen-rich feed.
The process according to this embodiment may further comprising a step of feeding a second portion of said first CO2-rich stream from the CO2-removal section to the first electrolysis unit as at least a portion of the first electrolysis feed.
All details of the plants according to the invention are applicable to the processes, mutatis mutandis.
Specific embodiments
Fig. 1 illustrates a general layout of the plant (100). Combined feed (3) of steam (2) and hydrocarbons (1) is fed to the reforming section (10) together with an oxygen-rich feed (4) so as to provide a first syngas stream (11). The first syngas stream (11) is fed to the CO2- removal section (30), and a first hydrogen-rich stream (31) and a first CO2-rich stream (32) are provided.
First electrolysis feed (9), e.g. water or CO2, or a mixture thereof, is provided to the first electrolysis unit (40), where it is electrolysed into at least an oxygen product gas and a cathode product gas stream (45).
A first portion (32a) of the first CO2-rich stream (32) from the CO2-removal section (30) is supplied to the anode of the first electrolysis unit (40) as a sweeping gas for the oxygen product gas. Another portion (32d) of the first CO2-rich stream (32) from the CO2-removal section (30) may be exported, as it may not be necessary that all of this stream is recycled through the electrolysis unit (40). A first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40) is outputted from the first electrolysis unit (40).
Figure 1 also shows, a first water-removal section (50) and a CO2 separation unit (60), both of which are optional. The first water-removal section (50) is arranged to receive at least a portion (41a) of the first combined gas stream (41) from the first electrolysis unit (40) and provide at least a first water-rich stream (51) and a second combined gas stream (52). The CO2 separation unit (60) is arranged to receive at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) and provide at least a second CO2-rich stream (61) and an oxygen-rich stream (62). As also shown in Figure 1, one or more streams is/are arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4). Such feeds are selected from: at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40), a second portion (52b) of said second combined gas stream (52), if present, and at least a portion of said oxygen-rich stream (62), if present.
Additional oxygen feed (6) may be supplied as at least a portion of the oxygen-rich feed, e.g. during startup. A steam feed (5) may be supplied to the reforming section (10).
Figs. 2A and 2B illustrate variations of a hydrogen plant, based on the layout of Figure 1. These figures comprise the same elements as Figure 1, with the addition of: shift section (20), PSA unit (70), which generates purified hydrogen stream (71) and a PSA off-gas stream (72), and second water-removal section (80), which provides a second water-rich stream (81) and a second purified hydrogen stream (82). In figure 2A, the PSA unit is located downstream the CC>2-removal section (30), while in figure 2B, the PSA unit is located upstream the CO2-removal section (30). Purified hydrogen stream (71) is exported from the plant. In this embodiment, the first electrolysis feed (9) is a water-rich feed.
Fig. 3 illustrates a syngas plant, based on the layout of Figure 1. Figure 3 comprises the same elements as Figure 1. Also in this embodiment, the first electrolysis feed (9) is a waterrich feed, which may comprise a portion of the first CO2-rich stream (32) from the CO2- removal section (30). The cathode product gas stream (45) from the first electrolysis unit (40) is a syngas product stream (43), which is exported from the plant. A CO2 recycle stream (36) from CO2-removal section (30) to the reforming section (10). It may not be possible to recycle all CO2-rich stream (32) through first electrolysis unit (40).
Fig. 4 illustrates a general layout of the plant, based on the layout of Figure 1. This layout includes a second electrolysis unit (140). A second portion (32b) of the first CO2-rich stream (32) from the CO2-removal section (30) is arranged to be supplied as electrolysis feed to the second electrolysis unit (140). The second electrolysis unit (140) electrolyses the second portion (32b) of the first CO2-rich stream (32) into an oxygen product gas and a CO- containing stream (142). Also, a third portion (32c) of the first CO2-rich stream (32) from the CO2-removal section (30) is supplied to the anode of the second electrolysis unit (140) as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream (141) comprising carbon dioxide and oxygen from said second electrolysis unit (140). Although the present invention is described with reference to a number of aspects and embodiments, the skilled person may combine such aspects and embodiments, within the scope of the appended claims. All documents referenced herein are incorporated by reference.

Claims

1. A plant (100), said plant (100) comprising a combined feed (3) of steam (2) and hydrocarbons (1); a reforming section (10) comprising an autothermal reformer, said reforming section (10) being arranged to receive said combined feed (3) and an oxygen-rich feed (4) and provide a first syngas stream (11); a CO2-removal section (30), arranged to receive first syngas stream (11) and provide a first hydrogen-rich stream (31) and a first CO2-rich stream (32); a first electrolysis unit (40) comprising an anode and a cathode; a first electrolysis feed (9) to said first electrolysis unit (40); wherein said first electrolysis unit (40) is arranged to electrolyse the first electrolysis feed (9) into at least an oxygen product gas and a cathode product gas stream (45); and wherein at least a first portion (32a) of said first CO2-rich stream (32) from the CO2- removal section (30) is arranged to be supplied to the anode of the first electrolysis unit (40) as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40); optionally, a first water-removal section (50) and a CO2 separation unit (60), wherein the first water-removal section (50) is arranged to receive at least a portion (41a) of said first combined gas stream (41) from said first electrolysis unit (40) and provide at least a first water-rich stream (51) and a second combined gas stream (52); and wherein said CO2 separation unit (60) is arranged to receive at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) and provide at least a second CO2-rich stream (61) and an oxygen-rich stream (62); and wherein one or more streams selected from: o at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40), o a second portion (52b) of said second combined gas stream (52), if present, and o at least a portion of said oxygen-rich stream (62), if present, is/are arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
2. The plant (100) according to claim 1, wherein said reforming section (10) further comprises a prereformer arranged upstream the autothermal reformer, and arranged to prereform the combined feed (3) to form a pre-reformed combined feed, and arranged to feed the prereformed combined feed to the autothermal reformer.
3. The plant (100) according to any one of the preceding claims, wherein the first electrolysis feed (9) is a water-rich feed and wherein said first electrolysis unit (40) is arranged to electrolyse the first electrolysis feed (9) into oxygen as anode product gas and hydrogen as cathode product gas.
4. The plant (100) according to any one of claims 1-2, wherein the first electrolysis feed (9) is a CO2-rich feed and wherein said first electrolysis unit (40) is arranged to electrolyse the first electrolysis feed (9) into oxygen as anode product gas and carbon monoxide as cathode product gas.
5. The plant (100) according to any one of the preceding claims, being a hydrogen plant, and further comprising : a shift section (20) arranged to receive the first syngas stream (11) from the reforming section (10), and provide a shifted first syngas stream (Ila) to the CO2-removal section (30), wherein the first electrolysis feed (9) is a water-rich feed and wherein said first electrolysis unit (40) is arranged to electrolyse the first electrolysis feed (9) into oxygen product gas and wherein the cathode product gas stream (45) is a hydrogenrich product stream (42), and wherein said hydrogen plant comprises a first water-removal section (50) and a CO2 separation unit (60), wherein the first water-removal section (50) is arranged to receive at least a portion (41a) of said first combined gas stream (41) from said first electrolysis unit (40) and provide at least a first water-rich stream (51) and a second combined gas stream (52); and wherein said CO2 separation unit (60) is arranged to receive at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) and provide at least a second CO2-rich stream (61) and an oxygen-rich stream (62); and wherein at least a portion of said oxygen-rich stream (62) is arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
6. The plant (100) according to claim 5, further comprising a pressure-swing absorption (PSA) unit (70), said PSA unit (70) being arranged to receive the first hydrogen-rich stream (31) from the CO2-removal section (30), and provide a purified hydrogen stream (71) and a PSA off-gas stream (72).
7. The plant (100) according to claim 5, further comprising a pressure-swing absorption (PSA) unit (70), said PSA unit (70) being arranged to receive the shifted first syngas stream (Ila) from the shift section (20) and provide a purified hydrogen stream (71) and a PSA off-gas stream (72), and feed said PSA off-gas stream (72) to said CO2- removal section (30).
8. The plant (100) according to any one of claims 4-7, wherein o at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40), and/or o a second portion (52b) of said second combined gas stream (52), is/are also arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
9. The plant (100) according to any one of claims 4-8, wherein the plant comprises a second water-removal section (80) arranged to receive at least a first portion (42a) of the hydrogen-rich product stream (42) from said first electrolysis unit (40) and provide at least a second water-rich stream (81) and a second purified hydrogen stream (82).
10. The plant (100) according to claim 9, wherein a second portion (42b) of the hydrogen-rich product stream (42) from the first electrolysis unit (40) is arranged to be fed to the inlet of the PSA unit (70).
11. The plant (100) according to any one of the preceding claims, being a syngas plant, wherein the first electrolysis feed (9) is a water-rich feed wherein said first electrolysis unit (40) is arranged to electrolyse the first electrolysis feed (9) into a cathode product gas stream (45) being a syngas product stream (43), and wherein at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40) is arranged to be fed to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
12. The plant according to claim 11, wherein the first electrolysis feed (9) comprises a second portion (32b) of said first CO2-rich stream (32) from the CO2-removal section (30).
13. The plant according to any one of claims 11-12, wherein the first electrolysis feed (9) comprises at least a portion of the second CO2-rich stream (61) from the CO2 separation unit (60).
14. The plant according to any one of claims 11-13, wherein the first electrolysis feed (9), being a CO2-rich feed, additionally comprises water.
15. The plant (100) according to any one of the preceding claims, said plant further comprising : a second electrolysis unit (140); wherein a second portion (32b) of the first CO2-rich stream (32) from the CO2- removal section (30) is arranged to be supplied as electrolysis feed to the second electrolysis unit (140), wherein said second electrolysis unit (140) is arranged to electrolyse the second portion (32b) of the first CO2-rich stream (32) into an oxygen product gas and a CO- containing stream (142); wherein a third portion (32c) of the first CO2-rich stream (32) from the CO2-removal section (30) is arranged to be supplied to the anode of the second electrolysis unit (140) as a sweeping gas for said oxygen product gas, so as to output a first combined gas stream (141) comprising carbon dioxide and oxygen from said second electrolysis unit (140).
16. The plant (100) according to claim 15, wherein a water feed (8) is arranged to be mixed with the second portion (32b) of the of the first CO2-rich stream (32), upstream the second electrolysis unit (140).
17. The plant (100) according to any one of the preceding claims, wherein the first and second electrolysis units (40, 140) comprises one or more solid oxide electrolyzer cells (SOECs).
18. A process for the production of hydrogen and/or syngas in the plant (100) according to any one of claims 1-17, said process comprising the steps of: providing a plant according to any one of claims 1-18; feeding the combined feed (3) of steam (2) and hydrocarbons (1), and the oxygen-rich feed (4), to the reforming section (10) comprising an autothermal reformer, so as to provide a first syngas stream (11); feeding the first syngas stream (11) to the CO2-removal section (30), so as to provide a first hydrogen-rich stream (31) and a first CO2-rich stream (32); feeding the first electrolysis feed (9) to the first electrolysis unit (40) and electrolysing it into at least an oxygen product gas and a cathode product gas stream (45); supplying at least a first portion (32a) of said first CO2-rich stream (32) from the CO2-removal section (30) to the anode of the first electrolysis unit (40) as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40); optionally, where the plant comprises a first water-removal section (50) and a CO2 separation unit (60), o feeding at least a portion (41a) of said first combined gas stream (41) from the first electrolysis unit (40) to the first water-removal section (50) so as to provide at least a first water-rich stream (51) and a second combined gas stream (52); and o feeding at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) to the CO2 separation unit (60) and providing at least a second CO2-rich stream (61) and an oxygen-rich stream (62); said process comprising the additional step of feeding one or more streams selected from: o at least a portion (41b) of the combined gas stream (41) from the first electrolysis unit (40), o a second portion (52b) of said second combined gas stream (52), if present, and o at least a portion of said oxygen-rich stream (62), if present, to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
19. A process for the production of hydrogen, in a hydrogen plant (100) according to any one of claims 4-10 and 15-17, said process comprising the steps of: providing a hydrogen plant (100) according to any one of claims 4-10 and 16-18; feeding the combined feed (3) of steam (2) and hydrocarbons (1), and the oxygen-rich feed (4), to the reforming section (10) comprising an autothermal reformer, so as to provide a first syngas stream (11); feeding the first syngas stream (11) from the reforming section (10) to the shift section (20), so as to provide a shifted first syngas stream (Ila) to the CO2- removal section (30), feeding the shifted first syngas stream (Ila) to the CO2-removal section (30), so as to provide a first hydrogen-rich stream (31) and a first CO2-rich stream (32); feeding the first electrolysis feed (9), being a water-rich feed, to the first electrolysis unit (40) and electrolysing it into at least an oxygen product gas and a cathode product gas stream (45) being a hydrogen-rich product stream (42); supplying at least a first portion (32a) of said first CO2-rich stream (32) from the CO2-removal section (30) to the anode of the first electrolysis unit (40) as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40); feeding at least a portion (41a) of said first combined gas stream (41) from the first electrolysis unit (40) to the first water-removal section (50) so as to provide at least a first water-rich stream (51) and a second combined gas stream (52); and feeding at least a portion (52a) of the second combined gas stream (52) from the first water-removal section (50) to the CO2 separation unit (60) and providing at least a second CO2-rich stream (61) and an oxygen-rich stream (62); said process comprising the additional step of feeding at least a portion of said oxygen-rich stream (62) to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
20. A process for the production of syngas, in a syngas plant (100) according to any one of claims 11-17 said process comprising the steps of: providing a syngas plant (100) according to any one of claims 11-18; feeding the combined feed (3) of steam (2) and hydrocarbons (1), and the oxygen-rich feed (4), to the reforming section (10) comprising an autothermal reformer, so as to provide a first syngas stream (11); feeding the first syngas stream (11) from the reforming section (10) to the shift section (20), so as to provide a shifted first syngas stream (Ila) to the CO2- removal section (30), feeding the shifted first syngas stream (I la) to the CO2-removal section (30), so as to provide a first hydrogen-rich stream (31) and a first CO2-rich stream (32); feeding the first electrolysis feed (9), being a water-rich feed, to the first electrolysis unit (40) and electrolysing it into at least an oxygen product gas and a cathode product gas stream (45) being a syngas product stream (43); supplying at least a first portion (32a) of said first CO2-rich stream (32) from the CO2-removal section (30) to the anode of the first electrolysis unit (40) as a sweeping gas for said oxygen product gas, and outputting a first combined gas stream (41) comprising carbon dioxide and oxygen from said electrolysis unit (40); feeding at least a portion (41a) of said first combined gas stream (41) from the first electrolysis unit (40) to the reforming section (10) as at least a portion of said oxygen-rich feed (4).
21. The process according to claim 20, further comprising a step of feeding a second portion (32b) of said first CO2-rich stream (32) from the CO2-removal section (30) to the first electrolysis unit (40) as at least a portion of the first electrolysis feed (9)
EP23828751.0A 2022-12-21 2023-12-14 Use of co2-rich gas as a sweeping gas in a chemical plant Pending EP4638827A1 (en)

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