WO2018202829A1 - Integrated process for producing c2+ hydrocarbons and a process system for such a process - Google Patents

Integrated process for producing c2+ hydrocarbons and a process system for such a process Download PDF

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WO2018202829A1
WO2018202829A1 PCT/EP2018/061455 EP2018061455W WO2018202829A1 WO 2018202829 A1 WO2018202829 A1 WO 2018202829A1 EP 2018061455 W EP2018061455 W EP 2018061455W WO 2018202829 A1 WO2018202829 A1 WO 2018202829A1
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unit
ocm
hydrocarbons
reactor
separating
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PCT/EP2018/061455
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French (fr)
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Guhan Mathivanan
Krister Fagerstolt
Tuomas Ouni
Eberhard Dreher
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Borealis Ag
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
    • C07C5/3332—Catalytic processes with metal oxides or metal sulfides
    • C—CHEMISTRY; METALLURGY
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    • C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
    • C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
    • C07C1/12—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon from carbon dioxide with hydrogen
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2/00—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms
    • C07C2/76—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen
    • C07C2/82—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen oxidative coupling
    • C07C2/84—Preparation of hydrocarbons from hydrocarbons containing a smaller number of carbon atoms by condensation of hydrocarbons with partial elimination of hydrogen oxidative coupling catalytic
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C—CHEMISTRY; METALLURGY
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    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
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    • C07C5/32—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by dehydrogenation with formation of free hydrogen
    • C07C5/327—Formation of non-aromatic carbon-to-carbon double bonds only
    • C07C5/333—Catalytic processes
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C7/00—Purification; Separation; Use of additives
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
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    • C07C2523/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • C07C2523/24—Chromium, molybdenum or tungsten
    • C07C2523/26—Chromium
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    • C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
    • C07C2523/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals
    • C07C2523/40—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals of the platinum group metals
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    • C07C2523/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of noble metals combined with metals, oxides or hydroxides provided for in groups C07C2523/02 - C07C2523/36
    • C07C2523/56—Platinum group metals
    • C07C2523/62—Platinum group metals with gallium, indium, thallium, germanium, tin or lead
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    • C07C2523/74—Iron group metals
    • C07C2523/755—Nickel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

Definitions

  • the present invention relates to an integrated process for producing C 2+ hydrocarbons and a process system for conducting the same.
  • C 2+ Hydrocarbons comprising two or more carbon atoms and including saturated C 2+ hydrocarbons or alkanes (such as ethane, propane, butane, pentane etc.) and unsaturated C 2+ hydrocarbons or alkenes (such as ethylene, propylene, butylene etc.) may be produced in different processes, such as by oxidative coupling of alkanes, in particular the oxidative coupling of methane (also known as OCM process).
  • OCM process oxidative coupling of alkanes
  • the oxidative coupling of alkanes in particular the oxidative coupling of methane, converts methane to valuable products as for example ethane and ethene.
  • methane is oxidized according to the following equation:
  • Suitable catalysts for OCM include various forms of iron oxide, manganese oxide, magnesium oxide, molybdenium oxide, cobalt oxide and others on various supports. Number of doping elements have also been proven to be useful in combination with the above catalysts.
  • the methane feedstock for the OCM reactor can be provided from various sources such as natural gas or from a methanizer in which carbon dioxide and hydrogen are reacted to me same.
  • the OCM reactor may also comprise a cracking unit for generating unsaturated alkenes, in particular ethene, from ethane. Ethane is thermally dehydrogenated via the following reaction:
  • the OCM process provides primarily ethene (or ethylene) that is an important chemical intermediate for the production of different plastics and compounds such as polyethylene plastics, polyvinylchloride, ethylene oxide, ethylbenzene, alcohols and other alkanes and alkenes.
  • hydrocarbons with saturated or unsaturated carbon-carbon bonds may also be obtained as side products.
  • Saturated hydrocarbons can include alkanes such as ethane, propane, butane, pentane and hexane.
  • Unsaturated hydrocarbons may include C 3+ hydrocarbons, such as propene.
  • the C 2+ hydrocarbons produced in the OCM process are separated from methane in a demethanizer unit and are typically fed in a subsequent step to a deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons comprising three or more carbon atoms, such as propane and propene.
  • Propene (or propylene) and propane that are produced as side products in the OCM process can be sold as refinery grade propylene (RGP) which is normally less valued than polymer grade propylene (PGP).
  • RGP refinery grade propylene
  • PGP polymer grade propylene
  • C 3 splitter In order to upgrade refinery grade propylene (RGP) to polymer grade propylene (PGP) propene and propane needs to be separated from each other. Such a separation is typically done in a so called C 3 splitter. A heat pump is sometimes installed in C 3 splitter to save energy. It is not always necessary, it is only installed to save operating expenses. C 3 splitter itself is a very big distillation tower and expensive as such. Alkane dehydrogenation process
  • hydrocarbons or alkanes in particular aliphatic hydrocarbons
  • the hydrocarbons propane, butane, isobutane, butenes and ethyl benzene are well known catalytically dehydrogenated to produce the respective propylene, butene, isobutene, butadiene and styrene.
  • Dehydrogenation reactions are strongly endothermic and thus, an increase of the heat supply favours the olefin conversion.
  • Houdry CATOFIN ® and OleflexTM are well known dehydrogenation processes where propene is produced from propane using a dehydrogenation catalyst.
  • the product mixture or effluent leaving the propane dehydrogenation reactor comprises besides the main product propene also hydrogen, ethane, ethene and methane.
  • an integrated process for producing C 2+ hydrocarbons preferably C 2+ saturated and unsaturated hydrocarbons (i.e. hydrocarbons having 2 and more carbon atoms)
  • the integrated process comprises a process for oxidative coupling of methane (OCM) which comprises the steps of
  • fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon product streams
  • the fractionation system comprises - at least one demethanizer unit for separating methane from C 2+ hydrocarbons
  • At least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons,
  • the integrated process comprises the steps of
  • a process is provided that allows the integration of an OCM process and a propane dehydrogenation process in such a manner that specific process units are now used for both process.
  • a C 3 splitter typically used in a propane dehydrogenation process is now also used for products of the OCM process.
  • the C 3 splitter has now two different feeds one from the OCM process and one from the propane dehydrogenation depicted in the following scheme:
  • the C 3 hydrocarbon feed from the OCM process would be introduced into the C 3 splitter at least one tray above the tray where the C 3+ hydrocarbon feed from the propane dehydrogenation process is introduced into the C 3 splitter.
  • a deethanizer unit (and also a depropanizer unit) in the OCM process may be at least reduced or is even no longer required. This is depicted in the following scheme:
  • Deethanizer unit Dehydrogenation (dehydrogenation process)
  • fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises
  • At least one demethanizer unit for separating methane from C 2+ hydrocarbons
  • deethanizer unit for separating C 2 hydrocarbons from C 3+ hydrocarbons
  • At least one one depropanizer unit for separating C 3 hydrocarbons, such as propane and propene, from C 4+ hydrocarbons, and
  • fractionation system comprises
  • deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons
  • C 3 splitter unit for separating propane and propene
  • the present integrated process comprises:
  • fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon product streams
  • the fractionation system comprises - at least one demethanizer unit for separating methane from C 2+ hydrocarbons
  • fractionation system comprises
  • At least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons, and
  • the OCM reactor effluent is fed to at least one compression unit that is arranged downstream of the OCM reactor before entering the at least one fractionation system.
  • the effluent leaving the OCM reactor comprises at least one C 2+ hydrocarbons (such as ethane, ethene but also higher hydrocarbons), carbon dioxide, carbon monoxide, hydrogen and methane.
  • the OCM effluent is subsequently separated into i) one first stream comprising at least a part of the C 2+ hydrocarbons and ii) a second stream comprising carbon monoxide (CO), carbon dioxide (C0 2 ), hydrogen (H 2 ) and methane (CH 4 ).
  • the separation of the OCM effluent into stream i) and stream ii) is preferably done in a least one C0 2 removal unit that is arranged downstream of the OCM reactor and the compression unit.
  • the first stream i) leaving the C0 2 removal unit comprising ethane as C 2+ compound is fed further into the fractionation system.
  • At least demethanizer unit as part of the fractionation system is arranged downstream of the C0 2 removal unit.
  • the methane separated in the demethanizer unit is fed to at least one methanation unit and further recycled back into the OCM reactor.
  • the second stream ii) leaving the C0 2 removal unit is fed into at least one methanation unit to generate a first OCM reactor feed comprising CH 4 from H 2 and C0 2 and/or CO.
  • a third stream iii) comprising CH 4 and H 2 from the demethanizer unit (De-C1 ) is fed into a methanation unit.
  • Hydrogen reacts with carbon monoxide and carbon dioxide in the methanation unit (as part of the OCM process) to methane in exothermic processes.
  • the heat generated may be used as heat input to other process units or for preheating reactants such as methane and/or an oxidizing agent prior to an OCM reaction.
  • the methanation reaction can take place in one or more reactors in series.
  • the methanation unit comprises a first reactor and the second reactor that can be operated as adiabatic reactors.
  • the methanation reaction requires a suitable catalyst.
  • nickel-based catalysts can be used that may include nickel supported on alumina.
  • a methanation catalyst can be tableted or extruded.
  • the shapes of such catalysts can be for example cylindrical, spherical or ring structure.
  • Methane synthesized in the at least one methanation unit is fed subsequently to at least one pre-heating unit before recycled back into the OCM reactor.
  • methane from the methanation unit further methane from natural gas may be used for the OCM reactor.
  • the C 2+ hydrocarbon effluent leaving the demethanizer unit is fed into at least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons.
  • the C 2 hydrocarbon effluent leaving the at least one deethanizer unit and that is fed to the at least one C 2 splitter comprises ethane, ethene and further methane.
  • the ethane leaving the at least one C 2 splitter unit may be subsequently recycled back to the
  • OCM reactor preferably to the cracking unit of the OCM reactor.
  • propane is reacted in an endothermic dehydrogenation reactor in the presence of a suitable catalyst such as chromium oxide or Pt-Sn based catalyst.
  • a typical Chromium oxide dehydrogenation catalyst manufactured on an alumina support comprises from about 17wt% to about 22 wt% Cr 2 0 3 .
  • These type of dehydrogenation catalyst are known for instance under the name Catofin® Standard catalyst (US 2008/0097134 A1 ).
  • the product gas mixture or dehdyrogenation reactor effluent leaving the dehydrogenation reactor goes to at least one separating unit comprising at least one cold box unit and at least one pressure swing adsorption unit (psa unit) that are arranged downstream of the propane dehydrogenation reactor.
  • the light gases including hydrogen are separated in the cold box unit or cold section unit.
  • the hydrogen from the light gases is then further separated from the remaining light gases using a pressure swing adsorption unit.
  • the liquid products from the cold box are sent further to at least one de-ethaniser unit as part of a fractionation system where components lighter than propene (for example ethane and ethene) are removed at the top.
  • components lighter than propene for example ethane and ethene
  • Propene and the other heavier components are sent to the C 3 unit (a C 3 splitter tower) where propene is obtained at the top.
  • the bottom stream or effluent of the C 3 splitter unit is then fed to at least one depropaniser unit as part of the dehydrogenation process where the components heavier (C 4+ hydrocarbons) then propane are removed at the bottom.
  • the propane leaving the at least one de-propanizing unit is recycled back into the propane dehydrogenation reactor.
  • the used catalyst from the dehydrogenation step may be regenerated in a regeneration step .
  • the present integrated process is conducted in an integrated process system for conducting a process for producing C 2+ hydrocarbons, wherein the process system comprises at least one OCM system comprising
  • At least one OCM reactor comprising at least one OCM catalyst unit for generating C 2+ hydrocarbons from methane and at least one cracking unit for generating C 2+ hydrocarbons, preferably ethene, from ethane; - at least one fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon products streams, wherein the fractionation system comprises at least one demethanizer unit for separating methane from C 2+ hydrocarbons, and at least one C 2 splitter unit for separating ethane and ethene, and/or
  • At least one deethanizer unit for separating C 2 hydrocarbons from C 3+ hydrocarbons, and at least one propane dehydrogenation system comprising
  • the fractionation system comprises at least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons, and at least one C 3 splitter unit for separating propane and propene
  • the at least one depropanizer unit in the OCM system is in fluid connection to the at least one C 3 splitter unit in the propane dehydrogenation system for feeding the C 3+ hydrocarbon effluent from the at least one deethanizer unit in the OCM system into the at least one C 3 splitter unit in the propane dehydrogenation system
  • the at least one demethanizer unit in the OCM system is in fluid connection to the at least one deethanizer unit in the propane dehydrogenation system for feeding the C 2+ hydrocarbon effluent from the demethanizer unit in the OCM system into the deethanizer unit in the propane dehydrogenation system and feeding the C 2 hydrocarbon eff
  • the present integrated process system comprises the following aspects: at least one OCM system comprising - at least one OCM reactor comprising at least one OCM catalyst unit for generating C 2+ hydrocarbons from methane and at least one cracking unit for generating C 2+ hydrocarbons, preferably ethene, from ethane; - optionally at least one C0 2 removal unit for removing C0 2 from the OCM reactor effluent,
  • fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon products streams
  • the fractionation system comprises at least one demethanizer unit for separating methane from C 2+ hydrocarbons, at least one deethanizer unit for separating C 2 hydrocarbons from C 3+ hydrocarbons, at least one depropanizer unit for separating C 3 hydrocarbons, such as propane and propene, from C 4+ hydrocarbons, and at least one propane dehydrogenation system comprising
  • the fractionation system comprises at least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons, and at least one C 3 splitter unit for separating propane and propene, wherein the at least one depropanizer unit in the OCM system is in fluid connection to the at least one C 3 splitter unit in the propane dehydrogenation system for feeding the C 3 hydrocarbon effluent from the at least one depropanizer unit in the OCM system into the at least one C 3 splitter unit in the propane dehydrogenation system,
  • the present integrated process system comprises: at least one OCM system comprising - at least one OCM reactor comprising at least one OCM catalyst unit for generating C 2+ hydrocarbons from methane and at least one cracking unit for generating C 2+ hydrocarbons, preferably ethene, from ethane; - at least one fractionation system for separating the C 2+ hydrocarbons in one or more hydrocarbon products streams, wherein the fractionation system comprises at least one demethanizer unit for separating methane from C 2+ hydrocarbons, at least one C 2 splitter unit for separating ethane and ethene, and at least one propane dehydrogenation system comprising - at least one propane dehydrogenation reactor for producing propene from propane,
  • the fractionation system comprises at least one deethanizer unit for separating C 2 hydrocarbons, such as ethane and ethene, from C 3+ hydrocarbons, and at least one C 3 splitter unit for separating propane and propene
  • the at least one demethanizer unit in the OCM system is in fluid connection to the at least one deethanizer unit in the propane dehydrogenation system for feeding the C 2+ hydrocarbon effluent from the demethanizer unit in the OCM system into the deethanizer unit in the propane dehydrogenation system and feeding the C 2 hydrocarbon effluent from the at least one deethanizer unit in the propane dehydrogenation system to the at least one C 2 splitter unit in the OCM system.
  • At least one at least one compression unit and at least C0 2 removal unit are arranged downstream of the OCM reactor and upstream of the at least one fractionation system. It is furthermore preferred that as part of the OCM system at least one methanation unit is arranged downstream of the at least one demethanizer unit. Downstream of the at least one demethanizer unit at least one deethanizer unit and at least one depropanizer unit are provide as further part of the OCM system described previously.
  • the dehydrogenation system comprises at least one separation unit arranged downstream of the propane dehydrogenation reactor.
  • the separation unit in the dehydrogenation system comprises at least one cold box for separating light gases from the product mixture leaving the propane dehydrogenation reactor and at least one pressure swing unit (psa) for further separating hydrogen from the light gases leaving the psa unit.
  • Cold box unit and psa unit are in thereby in fluid communication with each other.
  • the at least one de-ethanizer unit is arranged downstream of the at least separating unit in the propane dehydrogenation system.
  • Figure 1 A a scheme of a conventional stand-alone OCM process
  • Figure 1 B a scheme of a conventional Oleflex stand-alone propane dehydrogenation process
  • Figure 1 C a scheme of a conventional Catofin stand-alone propane dehydrogenation process
  • Figure 2A a scheme of a first embodiment of the present process
  • Figure 2B a scheme of a second embodiment of the present process
  • Figure 3A a scheme of a third embodiment of the present process
  • Figure 3B a scheme of a fourth embodiment of the present process
  • Fig. 1 A shows a schematic overview of a conventional OCM process.
  • the OCM process system 100 comprises an OCM reactor unit 101 with an OCM catalytic unit and the post-bed cracking unit (PBC) for generating olefins (for example ethene) from alkanes (for example ethane and/or propane).
  • OCM catalytic unit and PBC unit can be situated in separate reactors or can be integrated into the same reactor.
  • Methane (stream A 104) and oxygen (stream 103) as oxidizing agent are injected into the catalytic unit and ethane can be injected into the PBC unit.
  • methane is converted to C 2+ compounds and is subsequently directed to PBC unit in which one alkanes are converted to alkenes.
  • the stream A13 leaving the OCM reactor unit 101 is directed to a TLE and Quench tower (not shown) and further to a compression unit 107.
  • the OCM effluent gases are quenched with a cooling medium and any process condensates are condensed and removed.
  • the cooled OCM effluent is then set to the compression unit 107, which can comprise a single or multiple stages of compression.
  • the compression unit 107 can also comprise coolers and separator vessels which wasted pressure of the OCM effluent stream and water from the OCM effluent stream.
  • the product stream leaving the compression unit 107 is further transported to a carbon dioxide removal unit 1 10 which can remove carbon dioxide from the OCM product stream. At least a portion of the carbon dioxide can be directed to a methanation unit 1 1 1 . The other portion of the carbon dioxide can be directed for other uses (stream 1 13).
  • the carbon dioxide removal unit 1 10 can comprise pressure swing absorption unit (PSA) or can be based on any other membrane separation processes.
  • PSA pressure swing absorption unit
  • the effluent from the carbon dioxide removal unit can be treated (for example in the molecular sieve dryer).
  • the OCM product stream can be directed from the carbon dioxide removal unit 1 10 to a CDC and turboexpander unit (not shown).
  • CDC compression, drying, chilling
  • CDC compression, drying, chilling
  • the Turboexpander is used to provide cooling for chilling unit by expanding the pressurized demethaniser overhead to lower pressure and consequently to much lower temperature. This very low temp methane stream is then used to cool down the process gas through a heat exchanger.
  • the OCM product stream leaving the CDC / turboexpander unit is subsequently introduced to a demethanizer unit (De-C1 ) 1 14 which can separate all recover methane from higher molecular weight hydrocarbons (such as ethane, ethene, propene).
  • the demethanizer unit 1 14 may include one or more distillation columns.
  • the methane (stream 1 17) separated in the demethanizer unit 1 14 (and after PSA purge stream 1 15) can then be directed to the methanation unit 1 1 1 .
  • methanation unit 1 1 1 further methane is generated from carbon dioxide, carbon monoxide and hydrogen. Methane generated in the methanation unit 1 1 1 can then be directed to the OCM catalytic unit 101 .
  • Hydrogen content in the effluent stream can range between 5% and about 15%.
  • the content of carbon monoxide and carbon dioxide can range between one and 5%.
  • this effluent stream is directly recycled to the OCM reactor 101 .
  • carbon monoxide and hydrogen are recycled to the OCM reactor 101 along with methane they can react with oxygen to produce carbon dioxide and water causing negative impact to the overall process.
  • the stream comprising carbon dioxide, carbon monoxide and hydrogen is fed (after removal from the product stream in the carbon dioxide removal unit) to a methanation unit 1 1 1 .
  • the methanation unit 1 1 1 carbon monoxide and carbon dioxide react with hydrogen to methane in exothermic processes.
  • the heat generated may be used as heat input to other process units or for preheating reactants such as methane and/or an oxidizing agent prior to an OCM reaction.
  • the methanation reaction can take place in two or more reactors in series.
  • the methanation unit 1 1 1 comprises a first reactor and the second reactor that can be operated as adiabatic reactors.
  • the methanation reaction 1 1 1 requires a suitable catalyst.
  • nickel-based catalysts can be used that may include nickel supported on alumina.
  • the methanation reaction can produce water. Thus it is desirable to remove this water prior to recycling the methanation effluent to the OCM a reactor. This can be accomplished by lowering the temperature of the methanation effluent or applying any separation procedure for removing the water.in some embodiments at least about 70%, at least about 80% at least about 90% or at least about 99% of the water is removed from the methanation effluent prior to the OCM reactor. Removing the water can increase the lifetime and/or performance of the OCM catalyst.
  • Methane synthesized in the methanation unit 1 1 1 is subsequently mixed and replenished with fresh methane from natural gas (stream 108).
  • the mixed methane stream 104 enters then the catalytic unit of the OCM reactor 101 .
  • Higher molecular weight hydrocarbons separated from methane in the demethanizer unit 1 14 can then be directed to a deethanizer unit (De-C2 unit) 1 18.
  • C 2 compounds such as ethane and ethene
  • C 3+ compounds such as propane and propene
  • C 2 compounds are then directed from the deethanizer unit 1 18 to a C 2 splitter 121 which can separate ethane from ethene.
  • the C 2 splitter 121 can be a distillation column.
  • the C 2 splitter 121 can also be coupled to an acetylene converter 1 16 where acetylene (C 2 H 2 ) is reacted with hydrogen to generate ethane and/or ethene.
  • Recovered ethene (stream 122) can be employed for any downstream use (like polymer production) whereas ethane is subsequently recycled from the C 2 splitter 121 to the OCM reactor unit 101 , preferably to the cracking unit (PBC unit).
  • PBC unit cracking unit
  • C 3+ compounds separated in the deethanizer unit 1 18 from the C 2 compounds are further directed to a depropanizer unit (De-C3 unit) 123 in which C 3 compounds are separated from
  • the C 3 compounds stream (stream 120) comprises predominantly propene and propane.
  • the ethane (stream 105) recycled from the C 2 splitter 121 to the OCM reactor unit 101 is mixed and replenished with fresh ethane form a natural gas source (stream 102). Recycled ethane and fresh ethane enter the reactor unit as combined streams.
  • Table 1 below depicts the flow rate of the different streams in a conventional OCM process (as for example described in WO 2015/106023 A1 )
  • Fig. 1 B is schematic view of the known Oleflex propane dehydrogenation process.
  • Fresh propane feed is mixed with the recycle propane feed to form a combined feed and fed to a heater (not shown).
  • the heated feed is then reacts in dehydrogenation reactor 201 in the presence of a catalyst.
  • the product gas mixture along with unreacted propane goes to a compressor 210 and subsequently to the cold section or cold box 202 where light gases are separated.
  • the hydrogen from the light gases is then separated from the remaining light gases using a pressure swing adsorption (PSA) unit 203. Hydrogen and the other light gases exit the dehydrogenation system 200 as stream 21 1 .
  • PSA pressure swing adsorption
  • the liquid from the cold box 202 is then sent to a de-ethaniser 204 where components lighter than propene (such as methane and ethane) are removed at the top for export (stream 213).
  • Propene and the other heavier components are sent to a C 3 splitter tower 205 where propene is obtained (stream 212).
  • the bottom stream of C 3 splitter 205 is then fed to depropaniser (De-C3) 207 where the components heavier then propane (such as C 4+ compounds) are removed at the bottom (stream 209).
  • De-C3 depropaniser
  • the used catalyst from the dehydrogenation reactor 201 is regenerated in a regeneration section (not shown) and recycled back to the dehydrogenation reactor 201 .
  • Table 2 depicts the flow rate of the different streams in a conventional propane dehydrogenation process.
  • the flow values in the Table 2 are based on reactor effluent stream composition given by Chin et al. (Int. J. Chem., Nucl., Metallurgic. and Materials Engineering; 201 1 , Vol. 5; No. 4, pages 1 9-25) for a 500 kilo ton per year basis. It is assumed that all the H 2 and methane are separated in coldbox from C2+ components. In case of using PSA further, it can be assumed that H 2 will be further purified from methane. Also it is assumed that ethane and ethylene are separated from C 3+ components in deethaniser and polymer grade propylene is separated from the remaining components in C 3 splitter.
  • Fig. 1 C depicts a scheme of the known Catofin propane dehydrogenation process 200.
  • the CATOFIN propane dehydrogenation process is a cyclic process where during regeneration and reduction steps, heat is supplied to the catalyst bed and during dehydrogenation step catalyst bed cools down due to the endothermic dehydrogenation reaction.
  • Propylene production is normally controlled by equilibrium at the bottom section (US 2,41 9,997).
  • fresh propane is mixed with the recycle propane feed to form a combined feed and fed to a fired heater (not shown). The heated feed is then reacts in dehydrogenation reactor 201 in the presence of a catalyst.
  • the product gas mixture along with unreacted propane goes to a compressor 210 and subsequently to the cold section or cold box 202 where light gases are separated.
  • the hydrogen from the light gases is then separated from the remaining light gases using a pressure swing adsorption unit 203.
  • Hydrogen and the other light gases exit the dehydrogenation system 200 as stream 21 1 and are typically used as fuel gas.
  • the liquid from the cold box 202 is then sent to a de-ethaniser 204 where components lighter than propene (such as methane and ethane) are removed at the top for export (stream 213).
  • Propene and the other heavier components are sent to a C3 splitter tower 205 where propene is obtained (stream 212).
  • the bottom stream of C3 splitter 205 is recycled back then together with freshly injected propane (stream 203) to the dehydrogenation reactor 201 .
  • Fig. 2A illustrates a first embodiment of the present process.
  • the OCM product stream is directed from the carbon dioxide removal unit 1 1 1 to further work up units.
  • the OCM product stream enters as a demethanizer unit (De-C1 ) 1 14 which separates and recovers methane from higher molecular weight C 2+ hydrocarbons
  • the recovered methane is fed to the methanation unit (not shown).
  • the C 2+ hydrocarbon effluent is further directed from the demethanizer unit 1 14 to the deethanizer unit 1 18 for separating C 2 hydrocarbons (such as ethane and ethene) from C 3+ hydrocarbons.
  • the separated C 2 hydrocarbons are then transferred to a C 2 splitter (not shown).
  • the C 3+ hydrocarbons (stream 120) leaving the deethanizer unit 1 18 in the OCM process are now transferred to a C 3 splitter unit 205 in the propane dehydrogenation system.
  • propane is reacted to propene in the dehydrogenation reactor 201 .
  • the reactor effluent is subsequently fed to a separation unit (not shown) for separating light gases and a deethanizer unit 204.
  • the C 3+ hydrocarbon effluent leaving the deethanizer unit 204 is guided into a C 3 splitter for separating propane and propene.
  • the separated propene stream 212 consists essentially of polymer grade propene (PG propene).
  • PG propene polymer grade propene
  • Fig. 2B illustrates a second embodiment of the present process. Reference is made to the schemes shown in Figs. 1 A, 1 B and 1 C.
  • the C 3 hydrocarbon stream 120a leaving the depropanizer unit 123 in the OCM process are tunneled to the C 3 splitter 205 in the propane dehydrogenation process.
  • the amount of fresh propane (C3 LPG feed stream 203) that is required can be reduced by 20,7 kg per tonne OCM ethylene capacity.
  • the amount of polymer grade propene (stream 212) that can be obtained is increased by 39,1 kg per tonne OCM ethylene capacity.
  • the OCM refinery grade propylene product is upgraded into polymer grade propylene and propane.
  • Example 5 Fig. 3A illustrates a third embodiment of the present process.
  • ethane and oxygen enter the OCM reactor 101 .
  • the OCM reactor effluent (stream 106) is fed into the C0 2 removal unit 1 10. Part of the removed C0 2 will be guided into the methanation unit, whereas the remaining C0 2 part is vented out of the system (not shown).
  • the OCM product stream is directed from the carbon dioxide removal unit 1 10 to further work up units.
  • the OCM product stream enters as a demethanizer unit (De-C1 ) 1 14 which separates and recovers methane from higher molecular weight C2 + hydrocarbons (such as ethane, ethene, propene).
  • the recovered methane is fed to the methanation unit (not shown).
  • the C2 + hydrocarbon effluent from the demethanizer unit 1 14 in the OCM system is now directed to the deethanizer unit 204 as part of the propane dehydrogenation system for separating C 2 hydrocarbons (such as ethane and ethene) from C 3+ hydrocarbons.
  • the separated C 2 hydrocarbon stream 213 from the deethanizer unit 204 in the dehydrogenation system is then transferred back into the OCM system, more particular to the C 2 splitter 121 .
  • the C 2 splitter 121 ethane and ethene are separated from each other. While ethene is used for further purposes such as for polymerisation, ethane (stream 105) is recycled back to the cracking unit of the OCM reactor 101 .
  • propane is reacted to propene in the dehydrogenation reactor 201 .
  • the reactor effluent is subsequently fed to a separation unit (not shown) for separating light gases and a deethanizer unit 204.
  • the C 3+ hydrocarbon effluent leaving the deethanizer unit 204 is guided into a C 3 splitter for separating propane and propene.
  • the separated propene stream 212 consists essentially of polymer grade propene (PG propene).
  • the OCM process and the dehydrogenation system are thus combined such that C 2+ hydrocarbon stream from the OCM process is tunneled into the deethanizer unit in the dehydrogenation process and after separating off the C 3+ hydrocarbons the C2 hydrocarbons are tunneled back into the OCM system.
  • This allows the use of one common deethanizer unit 204 for both processes.
  • Fig. 3B illustrates a fourth embodiment of the present process. Reference is made to the schemes shown in Figs. 1 A, 1 B and 1 C.
  • the C 2+ hydrocarbon effluent from the demethanizer unit 1 14 in the OCM process is fed into the dehydrogenation process, specifically into the deethanizer unit 204 in the dehydrogenation process.
  • the separated C2 hydrocarbon stream 213 from the deethanizer unit 204 in the dehydrogenation system is then transferred back into the OCM system, more particular to the C2 splitter 121 .
  • ethane and ethene are separated from each other. While ethene is used for further purposes such as for polymerisation, ethane (stream 105) is recycled back to the cracking unit of the OCM reactor 101 .
  • OCM ethylene production capacity is increased by 9,3 kg per tonne PDH propylene capacity and OCM fresh ethane feed is decreased by 83,3 kg per tonne PDH propylene capacity.

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Abstract

The present invention relates to an integrated process for producing C2+ hydrocarbons, preferably C2+ saturated and unsaturated hydrocarbons, comprising a process for oxidative coupling of methane (OCM) which comprises the steps of - producing C2+ hydrocarbons from methane and at least one oxidizing agent, preferably oxygen, and from ethane in at least one OCM reactor comprising at least one OCM catalyst unit and at least one cracking unit; - transferring the OCM effluent from the at least one OCM reactor to at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises at least one demethanizer unit (114) for separating methane from C2+ hydrocarbons, at least one C2 splitter unit (121) for separating ethane and ethene, and/or at least one deethanizer unit (118) for separating C2 hydrocarbons from C3+ hydrocarbons, and a propane dehydrogenation process which comprises the steps of - producing propene from propane in at least one dehydrogenation reactor (201); - transferring the dehydrogenation reactor effluent from the at least one dehydrogenation reactor to at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit (204) for separating C2 hydrocarbons, from C3+ hydrocarbons, and at least one C3 splitter unit (205) for separating propane and propene, wherein the C3 hydrocarbon effluent from the at least one deethanizer unit (118) in the OCM process is fed into the at least one C3 splitter unit (205) in the propane dehydrogenation process and/or the C2+ hydrocarbon effluent from the at least one demethanizer unit (107) in the OCM process is fed into the at least one deethanizer unit (204) in the propane dehydrogenation process and the C2 hydrocarbon effluent from the at least one deethanizer unit (204) in the propane dehydrogenation process is fed to the at least one C2 splitter unit (121) in the OCM process.

Description

INTEGRATED PROCESS FOR PRODUCING C2+ HYDROCARBONS AND A
PROCESS SYSTEM FOR SUCH A PROCESS
The present invention relates to an integrated process for producing C2+ hydrocarbons and a process system for conducting the same.
Description
C2+ Hydrocarbons comprising two or more carbon atoms and including saturated C2+ hydrocarbons or alkanes (such as ethane, propane, butane, pentane etc.) and unsaturated C2+ hydrocarbons or alkenes (such as ethylene, propylene, butylene etc.) may be produced in different processes, such as by oxidative coupling of alkanes, in particular the oxidative coupling of methane (also known as OCM process). OCM process
The oxidative coupling of alkanes, in particular the oxidative coupling of methane, converts methane to valuable products as for example ethane and ethene. In the course of the oxidative coupling process methane is oxidized according to the following equation:
2 CH4 + 02→ C2H4 + 2 H20. This reaction is exothermic and is typically conducted at high temperatures in the range between 750 °C to 950^. In the course of the reaction methane is activated on the catalytic surface forming methyl radicals, which subsequently react in the gas phase with each other forming higher, long chain hydrocarbons such as ethane or dehydrogenation products thereof such as ethene.
Suitable catalysts for OCM include various forms of iron oxide, manganese oxide, magnesium oxide, molybdenium oxide, cobalt oxide and others on various supports. Number of doping elements have also been proven to be useful in combination with the above catalysts. The methane feedstock for the OCM reactor can be provided from various sources such as natural gas or from a methanizer in which carbon dioxide and hydrogen are reacted to me same. Besides a catalyst unit for oxidative coupling of methane the OCM reactor may also comprise a cracking unit for generating unsaturated alkenes, in particular ethene, from ethane. Ethane is thermally dehydrogenated via the following reaction:
Figure imgf000003_0001
This reaction is endothermic (ΔΗ = -144 kJ/mol) and can utilize the exothermic reaction heat produced during methane conversion in the OCM catalyst unit.
The OCM process provides primarily ethene (or ethylene) that is an important chemical intermediate for the production of different plastics and compounds such as polyethylene plastics, polyvinylchloride, ethylene oxide, ethylbenzene, alcohols and other alkanes and alkenes.
Besides ethene a variety of other hydrocarbons such as hydrocarbons with saturated or unsaturated carbon-carbon bonds may also be obtained as side products. Saturated hydrocarbons can include alkanes such as ethane, propane, butane, pentane and hexane. Unsaturated hydrocarbons may include C3+ hydrocarbons, such as propene.
The C2+ hydrocarbons produced in the OCM process are separated from methane in a demethanizer unit and are typically fed in a subsequent step to a deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons comprising three or more carbon atoms, such as propane and propene.
Propene (or propylene) and propane that are produced as side products in the OCM process can be sold as refinery grade propylene (RGP) which is normally less valued than polymer grade propylene (PGP).
In order to upgrade refinery grade propylene (RGP) to polymer grade propylene (PGP) propene and propane needs to be separated from each other. Such a separation is typically done in a so called C3 splitter. A heat pump is sometimes installed in C3 splitter to save energy. It is not always necessary, it is only installed to save operating expenses. C3 splitter itself is a very big distillation tower and expensive as such. Alkane dehydrogenation process
Dehydrogenation of hydrocarbons or alkanes, in particular aliphatic hydrocarbons, to convert them into to their respective olefins is a well-known process. For example, the hydrocarbons propane, butane, isobutane, butenes and ethyl benzene are well known catalytically dehydrogenated to produce the respective propylene, butene, isobutene, butadiene and styrene. Dehydrogenation reactions are strongly endothermic and thus, an increase of the heat supply favours the olefin conversion.
In particular, dehydrogenation of paraffinic and other hydrocarbons such as propane dehydrogenation (reaction 1 ) or butane dehydrogenation (reaction 2) or i-butane dehydrogenation (reaction 3) are well known: C3H8 ^ C3H6 + H2 (1 ) C4HW ^ C4H6 + 2H2 (2) i - C4HW i - C4HS + H2 (3)
Houdry CATOFIN® and Oleflex™ are well known dehydrogenation processes where propene is produced from propane using a dehydrogenation catalyst.
The product mixture or effluent leaving the propane dehydrogenation reactor comprises besides the main product propene also hydrogen, ethane, ethene and methane.
In order to optimize the Capex intensive propane dehydrogenation process and OCM process, it would be beneficial to integrate or share process units of PDH process with OCM process.
It is thus an object of the present invention to provide an integrated process that allows the synthesis of C2+ hydrocarbons and is at the same time less cost intensive and more efficient.
This object is being solved by an integrated process for producing C2+ hydrocarbons and a process system for conducting such a process as defined in the claims. Accordingly, an integrated process for producing C2+ hydrocarbons, preferably C2+ saturated and unsaturated hydrocarbons (i.e. hydrocarbons having 2 and more carbon atoms), is provided, wherein the integrated process comprises a process for oxidative coupling of methane (OCM) which comprises the steps of
- producing C2+ hydrocarbons from methane and at least one oxidizing agent, preferably oxygen, and from ethane in at least one OCM reactor comprising at least one OCM catalyst unit and at least one cracking unit,
- transferring at least one OCM effluent from the at least one OCM reactor to at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises - at least one demethanizer unit for separating methane from C2+ hydrocarbons, and
- at least one C2 splitter unit for separating ethane and ethene, and/or
- at least one deethanizer unit for separating C2 hydrocarbons from C3+ hydrocarbons, and a propane dehydrogenation process which comprises the steps of
- producing propene from propane in at least one dehydrogenation reactor, - transferring at least one dehydrogenation reactor effluent from the at least one dehydrogenation reactor to at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises
- at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons,
- at least one C3 splitter unit for separating propane and propene, and
- optionally at least one depropanizer for separating C4+ hydrocarbons. According to the invention the integrated process comprises the steps of
- feeding the C3+ hydrocarbon effluent from the at least one deethanizer unit in the OCM process into the at least one C3 splitter unit in the propane dehydrogenation process and/or
- feeding the C2+ hydrocarbon effluent from the at least one demethanizer unit in the OCM process into the at least one deethanizer unit in the propane dehydrogenation process, and
- feeding the C2 hydrocarbon effluent from the at least one deethanizer unit in the propane dehydrogenation process to the at least one C2 splitter unit in the OCM process. Specifically, a process is provided that allows the integration of an OCM process and a propane dehydrogenation process in such a manner that specific process units are now used for both process.
On the one hand a C3 splitter typically used in a propane dehydrogenation process is now also used for products of the OCM process. In the present integrated process the C3 splitter has now two different feeds one from the OCM process and one from the propane dehydrogenation depicted in the following scheme:
C3 hydrocarbons as side
products from the OCM
process
Polymer grade
C3 splitter propylene
PDH process
propane/propylene
In a preferred embodiment the C3 hydrocarbon feed from the OCM process would be introduced into the C3 splitter at least one tray above the tray where the C3+ hydrocarbon feed from the propane dehydrogenation process is introduced into the C3 splitter. On the other hand, by feeding the C2+ hydrocarbon effluent from the demethanizer unit in the OCM process to the deethanizer unit in a propane dehydrogenation process a deethanizer unit (and also a depropanizer unit) in the OCM process may be at least reduced or is even no longer required. This is depicted in the following scheme:
OCM reactor Demethanizer unit C2+ hydrocarbon
effluent (OCM process) effluent
Figure imgf000007_0001
Deethanizer unit Dehydrogenation (dehydrogenation process)
reactor effluent
C2 hydrocarbon
effluent hydrocarbon effluent
Figure imgf000007_0002
C2 Splitter C3 Splitter
(OCM process) (dehydrogenation process)
By integrating these units of a dehydrogenation process with an OCM process additional investment cost of PDH/OCM process can be decreased.
In a first preferred embodiment the present integrated process comprises the following aspects:
- producing C2+ hydrocarbons from methane and at least one oxidizing agent, preferably oxygen, and from ethane in at least one OCM reactor comprising at least one OCM catalyst unit and at least one cracking unit,
- transferring the OCM effluent to at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises
- at least one demethanizer unit for separating methane from C2+ hydrocarbons, - at least one deethanizer unit for separating C2 hydrocarbons from C3+ hydrocarbons,
- at least one one depropanizer unit for separating C3 hydrocarbons, such as propane and propene, from C4+ hydrocarbons, and
- producing propene from propane in at least one propane dehydrogenation reactor,
- transferring the dehydrogenation reactor effluent to at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises
- at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons, - at least one C3 splitter unit for separating propane and propene, and
- optionally at least one depropanizer for separating C4+; and feeding the C3 hydrocarbon effluent from the at least one deethanizer unit (and optionally depropanizer unit) in the OCM process into the at least one C3 splitter unit in the propane dehydrogenation process In a second preferred embodiment the present integrated process comprises:
- producing C2+ hydrocarbons from methane and at least one oxidizing agent, preferably oxygen, and from ethane in at least one OCM reactor comprising at least one OCM catalyst unit and at least one cracking unit,
- transferring the OCM effluent to at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises - at least one demethanizer unit for separating methane from C2+ hydrocarbons, and
- at least one C2 splitter unit for separating ethane and ethene, - producing propene from propane in at least one propane dehydrogenation reactor,
- transferring the dehydrogenation reactor effluent to at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises
- at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons, and
- feeding the C2+ hydrocarbon effluent from the at least one demethanizer unit in the OCM process into the at least one deethanizer unit in the propane dehydrogenation process, and
- feeding the C2 hydrocarbon effluent from the at least one deethanizer unit in the propane dehydrogenation process to the at least one C2 splitter unit in the OCM process. In another embodiment of the present integrated process the OCM reactor effluent is fed to at least one compression unit that is arranged downstream of the OCM reactor before entering the at least one fractionation system.
Typically, in an OCM process the effluent leaving the OCM reactor comprises at least one C2+ hydrocarbons (such as ethane, ethene but also higher hydrocarbons), carbon dioxide, carbon monoxide, hydrogen and methane. The OCM effluent is subsequently separated into i) one first stream comprising at least a part of the C2+ hydrocarbons and ii) a second stream comprising carbon monoxide (CO), carbon dioxide (C02), hydrogen (H2) and methane (CH4). The separation of the OCM effluent into stream i) and stream ii) is preferably done in a least one C02 removal unit that is arranged downstream of the OCM reactor and the compression unit.
The first stream i) leaving the C02 removal unit comprising ethane as C2+ compound is fed further into the fractionation system.
Here, in a further embodiment of the present process at least demethanizer unit as part of the fractionation system is arranged downstream of the C02 removal unit. The methane separated in the demethanizer unit is fed to at least one methanation unit and further recycled back into the OCM reactor. The second stream ii) leaving the C02 removal unit is fed into at least one methanation unit to generate a first OCM reactor feed comprising CH4 from H2 and C02 and/or CO. Besides the second stream a third stream iii) comprising CH4 and H2 from the demethanizer unit (De-C1 ) is fed into a methanation unit.
Hydrogen reacts with carbon monoxide and carbon dioxide in the methanation unit (as part of the OCM process) to methane in exothermic processes. The heat generated may be used as heat input to other process units or for preheating reactants such as methane and/or an oxidizing agent prior to an OCM reaction.
The methanation reaction can take place in one or more reactors in series. In an embodiment the methanation unit comprises a first reactor and the second reactor that can be operated as adiabatic reactors. The methanation reaction requires a suitable catalyst. For example, nickel-based catalysts can be used that may include nickel supported on alumina. A methanation catalyst can be tableted or extruded. The shapes of such catalysts can be for example cylindrical, spherical or ring structure. Methane synthesized in the at least one methanation unit is fed subsequently to at least one pre-heating unit before recycled back into the OCM reactor. Besides methane from the methanation unit further methane from natural gas may be used for the OCM reactor.
In a further variant of the present integrated process the C2+ hydrocarbon effluent leaving the demethanizer unit is fed into at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons.
It is further preferred, if the C2 hydrocarbon effluent leaving the at least one deethanizer unit and that is fed to the at least one C2 splitter comprises ethane, ethene and further methane. The ethane leaving the at least one C2 splitter unit may be subsequently recycled back to the
OCM reactor, preferably to the cracking unit of the OCM reactor.
In the dehydrogenation process propane is reacted in an endothermic dehydrogenation reactor in the presence of a suitable catalyst such as chromium oxide or Pt-Sn based catalyst. A typical Chromium oxide dehydrogenation catalyst manufactured on an alumina support comprises from about 17wt% to about 22 wt% Cr203. These type of dehydrogenation catalyst are known for instance under the name Catofin® Standard catalyst (US 2008/0097134 A1 ). The product gas mixture or dehdyrogenation reactor effluent leaving the dehydrogenation reactor goes to at least one separating unit comprising at least one cold box unit and at least one pressure swing adsorption unit (psa unit) that are arranged downstream of the propane dehydrogenation reactor. The light gases including hydrogen are separated in the cold box unit or cold section unit. The hydrogen from the light gases is then further separated from the remaining light gases using a pressure swing adsorption unit.
The liquid products from the cold box are sent further to at least one de-ethaniser unit as part of a fractionation system where components lighter than propene (for example ethane and ethene) are removed at the top. Propene and the other heavier components are sent to the C3 unit (a C3 splitter tower) where propene is obtained at the top.
The bottom stream or effluent of the C3 splitter unit is then fed to at least one depropaniser unit as part of the dehydrogenation process where the components heavier (C4+ hydrocarbons) then propane are removed at the bottom. The propane leaving the at least one de-propanizing unit is recycled back into the propane dehydrogenation reactor.
The used catalyst from the dehydrogenation step may be regenerated in a regeneration step .
The present integrated process is conducted in an integrated process system for conducting a process for producing C2+ hydrocarbons, wherein the process system comprises at least one OCM system comprising
- at least one OCM reactor comprising at least one OCM catalyst unit for generating C2+ hydrocarbons from methane and at least one cracking unit for generating C2+ hydrocarbons, preferably ethene, from ethane; - at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon products streams, wherein the fractionation system comprises at least one demethanizer unit for separating methane from C2+ hydrocarbons, and at least one C2 splitter unit for separating ethane and ethene, and/or
at least one deethanizer unit for separating C2 hydrocarbons from C3+ hydrocarbons, and at least one propane dehydrogenation system comprising
- at least one propane dehydrogenation reactor for producing propene from propane,
- at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons, and at least one C3 splitter unit for separating propane and propene, wherein the at least one depropanizer unit in the OCM system is in fluid connection to the at least one C3 splitter unit in the propane dehydrogenation system for feeding the C3+ hydrocarbon effluent from the at least one deethanizer unit in the OCM system into the at least one C3 splitter unit in the propane dehydrogenation system, and/or the at least one demethanizer unit in the OCM system is in fluid connection to the at least one deethanizer unit in the propane dehydrogenation system for feeding the C2+ hydrocarbon effluent from the demethanizer unit in the OCM system into the deethanizer unit in the propane dehydrogenation system and feeding the C2 hydrocarbon effluent from the at least one deethanizer unit in the propane dehydrogenation system to the at least one C2 splitter unit in the OCM system. In a first preferred embodiment the present integrated process system comprises the following aspects: at least one OCM system comprising - at least one OCM reactor comprising at least one OCM catalyst unit for generating C2+ hydrocarbons from methane and at least one cracking unit for generating C2+ hydrocarbons, preferably ethene, from ethane; - optionally at least one C02 removal unit for removing C02 from the OCM reactor effluent,
- at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon products streams, wherein the fractionation system comprises at least one demethanizer unit for separating methane from C2+ hydrocarbons, at least one deethanizer unit for separating C2 hydrocarbons from C3+ hydrocarbons, at least one depropanizer unit for separating C3 hydrocarbons, such as propane and propene, from C4+ hydrocarbons, and at least one propane dehydrogenation system comprising
- at least one propane dehydrogenation reactor for producing propene from propane,
- at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons, and at least one C3 splitter unit for separating propane and propene, wherein the at least one depropanizer unit in the OCM system is in fluid connection to the at least one C3 splitter unit in the propane dehydrogenation system for feeding the C3 hydrocarbon effluent from the at least one depropanizer unit in the OCM system into the at least one C3 splitter unit in the propane dehydrogenation system,
In a second preferred embodiment the present integrated process system comprises: at least one OCM system comprising - at least one OCM reactor comprising at least one OCM catalyst unit for generating C2+ hydrocarbons from methane and at least one cracking unit for generating C2+ hydrocarbons, preferably ethene, from ethane; - at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon products streams, wherein the fractionation system comprises at least one demethanizer unit for separating methane from C2+ hydrocarbons, at least one C2 splitter unit for separating ethane and ethene, and at least one propane dehydrogenation system comprising - at least one propane dehydrogenation reactor for producing propene from propane,
- at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit for separating C2 hydrocarbons, such as ethane and ethene, from C3+ hydrocarbons, and at least one C3 splitter unit for separating propane and propene, wherein the at least one demethanizer unit in the OCM system is in fluid connection to the at least one deethanizer unit in the propane dehydrogenation system for feeding the C2+ hydrocarbon effluent from the demethanizer unit in the OCM system into the deethanizer unit in the propane dehydrogenation system and feeding the C2 hydrocarbon effluent from the at least one deethanizer unit in the propane dehydrogenation system to the at least one C2 splitter unit in the OCM system.
In a variant of the integrated process system at least one at least one compression unit and at least C02 removal unit (as part of the OCM system) are arranged downstream of the OCM reactor and upstream of the at least one fractionation system. It is furthermore preferred that as part of the OCM system at least one methanation unit is arranged downstream of the at least one demethanizer unit. Downstream of the at least one demethanizer unit at least one deethanizer unit and at least one depropanizer unit are provide as further part of the OCM system described previously.
In a further embodiment of the present integrated system the dehydrogenation system comprises at least one separation unit arranged downstream of the propane dehydrogenation reactor. The separation unit in the dehydrogenation system comprises at least one cold box for separating light gases from the product mixture leaving the propane dehydrogenation reactor and at least one pressure swing unit (psa) for further separating hydrogen from the light gases leaving the psa unit. Cold box unit and psa unit are in thereby in fluid communication with each other.
In yet another embodiment of the present process system the at least one de-ethanizer unit is arranged downstream of the at least separating unit in the propane dehydrogenation system.
The functionalities of the process system units and further system units are described in detail above. The invention is further described in more detail by means of examples with reference to the figures. It shows:
Figure 1 A a scheme of a conventional stand-alone OCM process;
Figure 1 B a scheme of a conventional Oleflex stand-alone propane dehydrogenation process;
Figure 1 C a scheme of a conventional Catofin stand-alone propane dehydrogenation process;
Figure 2A a scheme of a first embodiment of the present process;
Figure 2B a scheme of a second embodiment of the present process; Figure 3A a scheme of a third embodiment of the present process; and
Figure 3B a scheme of a fourth embodiment of the present process; Example 1 :
Fig. 1 A shows a schematic overview of a conventional OCM process.
The OCM process system 100 comprises an OCM reactor unit 101 with an OCM catalytic unit and the post-bed cracking unit (PBC) for generating olefins (for example ethene) from alkanes (for example ethane and/or propane). OCM catalytic unit and PBC unit can be situated in separate reactors or can be integrated into the same reactor.
Methane (stream A 104) and oxygen (stream 103) as oxidizing agent are injected into the catalytic unit and ethane can be injected into the PBC unit. In the catalytic unit methane is converted to C2+ compounds and is subsequently directed to PBC unit in which one alkanes are converted to alkenes. The stream A13 leaving the OCM reactor unit 101 is directed to a TLE and Quench tower (not shown) and further to a compression unit 107.
In the quench tower the OCM effluent gases are quenched with a cooling medium and any process condensates are condensed and removed. The cooled OCM effluent is then set to the compression unit 107, which can comprise a single or multiple stages of compression. The compression unit 107 can also comprise coolers and separator vessels which wasted pressure of the OCM effluent stream and water from the OCM effluent stream.
The product stream leaving the compression unit 107 is further transported to a carbon dioxide removal unit 1 10 which can remove carbon dioxide from the OCM product stream. At least a portion of the carbon dioxide can be directed to a methanation unit 1 1 1 . The other portion of the carbon dioxide can be directed for other uses (stream 1 13).
The carbon dioxide removal unit 1 10 can comprise pressure swing absorption unit (PSA) or can be based on any other membrane separation processes. The effluent from the carbon dioxide removal unit can be treated (for example in the molecular sieve dryer).
Next the OCM product stream can be directed from the carbon dioxide removal unit 1 10 to a CDC and turboexpander unit (not shown). CDC (compression, drying, chilling) train in OCM first precools C02-free gas from C02 removal, then removes any water by molecular sieve absorbents and the cools down the process gas in order to be able to separate methane from C2+ by distillation. The Turboexpander is used to provide cooling for chilling unit by expanding the pressurized demethaniser overhead to lower pressure and consequently to much lower temperature. This very low temp methane stream is then used to cool down the process gas through a heat exchanger.
The OCM product stream leaving the CDC / turboexpander unit is subsequently introduced to a demethanizer unit (De-C1 ) 1 14 which can separate all recover methane from higher molecular weight hydrocarbons (such as ethane, ethene, propene). The demethanizer unit 1 14 may include one or more distillation columns.
The methane (stream 1 17) separated in the demethanizer unit 1 14 (and after PSA purge stream 1 15) can then be directed to the methanation unit 1 1 1 . In the methanation unit 1 1 1 further methane is generated from carbon dioxide, carbon monoxide and hydrogen. Methane generated in the methanation unit 1 1 1 can then be directed to the OCM catalytic unit 101 .
In side reactions of the OCM significant amounts of hydrogen, carbon monoxide and carbon dioxide are formed and are thus contained in the OCM effluent stream. Hydrogen content in the effluent stream can range between 5% and about 15%. The content of carbon monoxide and carbon dioxide can range between one and 5%.
In some cases this effluent stream is directly recycled to the OCM reactor 101 . However, if carbon monoxide and hydrogen are recycled to the OCM reactor 101 along with methane they can react with oxygen to produce carbon dioxide and water causing negative impact to the overall process.
Thus, in order to make effectively use of the side products the stream comprising carbon dioxide, carbon monoxide and hydrogen is fed (after removal from the product stream in the carbon dioxide removal unit) to a methanation unit 1 1 1 .
In the methanation unit 1 1 1 carbon monoxide and carbon dioxide react with hydrogen to methane in exothermic processes. The heat generated may be used as heat input to other process units or for preheating reactants such as methane and/or an oxidizing agent prior to an OCM reaction.
The methanation reaction can take place in two or more reactors in series. In an embodiment the methanation unit 1 1 1 comprises a first reactor and the second reactor that can be operated as adiabatic reactors. The methanation reaction 1 1 1 requires a suitable catalyst. For example, nickel-based catalysts can be used that may include nickel supported on alumina.
The methanation reaction can produce water. Thus it is desirable to remove this water prior to recycling the methanation effluent to the OCM a reactor. This can be accomplished by lowering the temperature of the methanation effluent or applying any separation procedure for removing the water.in some embodiments at least about 70%, at least about 80% at least about 90% or at least about 99% of the water is removed from the methanation effluent prior to the OCM reactor. Removing the water can increase the lifetime and/or performance of the OCM catalyst.
Methane synthesized in the methanation unit 1 1 1 is subsequently mixed and replenished with fresh methane from natural gas (stream 108). The mixed methane stream 104 enters then the catalytic unit of the OCM reactor 101 . Higher molecular weight hydrocarbons separated from methane in the demethanizer unit 1 14 can then be directed to a deethanizer unit (De-C2 unit) 1 18. In the deethanizer unit 1 18 C2 compounds (such as ethane and ethene) are separated from C3+ compounds (such as propane and propene). C2 compounds are then directed from the deethanizer unit 1 18 to a C2 splitter 121 which can separate ethane from ethene. The C2 splitter 121 can be a distillation column. The C2 splitter 121 can also be coupled to an acetylene converter 1 16 where acetylene (C2H2) is reacted with hydrogen to generate ethane and/or ethene. Recovered ethene (stream 122) can be employed for any downstream use (like polymer production) whereas ethane is subsequently recycled from the C2 splitter 121 to the OCM reactor unit 101 , preferably to the cracking unit (PBC unit).
C3+ compounds separated in the deethanizer unit 1 18 from the C2 compounds are further directed to a depropanizer unit (De-C3 unit) 123 in which C3 compounds are separated from
C4+ compounds comprising 4 and more carbon atoms. The C3 compounds stream (stream 120) comprises predominantly propene and propane.
The ethane (stream 105) recycled from the C2 splitter 121 to the OCM reactor unit 101 is mixed and replenished with fresh ethane form a natural gas source (stream 102). Recycled ethane and fresh ethane enter the reactor unit as combined streams. Table 1 below depicts the flow rate of the different streams in a conventional OCM process (as for example described in WO 2015/106023 A1 )
Figure imgf000019_0001
Table 1 : Flow table OCM unit streams (in Ib/hr) Example 2:
Fig. 1 B is schematic view of the known Oleflex propane dehydrogenation process.
Fresh propane feed is mixed with the recycle propane feed to form a combined feed and fed to a heater (not shown). The heated feed is then reacts in dehydrogenation reactor 201 in the presence of a catalyst. The product gas mixture along with unreacted propane goes to a compressor 210 and subsequently to the cold section or cold box 202 where light gases are separated. The hydrogen from the light gases is then separated from the remaining light gases using a pressure swing adsorption (PSA) unit 203. Hydrogen and the other light gases exit the dehydrogenation system 200 as stream 21 1 .
The liquid from the cold box 202 is then sent to a de-ethaniser 204 where components lighter than propene (such as methane and ethane) are removed at the top for export (stream 213). Propene and the other heavier components are sent to a C3 splitter tower 205 where propene is obtained (stream 212). The bottom stream of C3 splitter 205 is then fed to depropaniser (De-C3) 207 where the components heavier then propane (such as C4+ compounds) are removed at the bottom (stream 209). Propane together with freshly injected propane (stream 203) is recycled back from the De-C3 unit 207 to the dehydrogenation reactor 201 .
The used catalyst from the dehydrogenation reactor 201 is regenerated in a regeneration section (not shown) and recycled back to the dehydrogenation reactor 201 .
Table 2 below depicts the flow rate of the different streams in a conventional propane dehydrogenation process.
The flow values in the Table 2 are based on reactor effluent stream composition given by Chin et al. (Int. J. Chem., Nucl., Metallurgic. and Materials Engineering; 201 1 , Vol. 5; No. 4, pages 1 9-25) for a 500 kilo ton per year basis. It is assumed that all the H2 and methane are separated in coldbox from C2+ components. In case of using PSA further, it can be assumed that H2 will be further purified from methane. Also it is assumed that ethane and ethylene are separated from C3+ components in deethaniser and polymer grade propylene is separated from the remaining components in C3 splitter.
Figure imgf000020_0001
Table 2: Flow table PDH unit streams
Fig. 1 C depicts a scheme of the known Catofin propane dehydrogenation process 200. The CATOFIN propane dehydrogenation process is a cyclic process where during regeneration and reduction steps, heat is supplied to the catalyst bed and during dehydrogenation step catalyst bed cools down due to the endothermic dehydrogenation reaction. Propylene production is normally controlled by equilibrium at the bottom section (US 2,41 9,997). According to the scheme of Fig. 1 C fresh propane is mixed with the recycle propane feed to form a combined feed and fed to a fired heater (not shown). The heated feed is then reacts in dehydrogenation reactor 201 in the presence of a catalyst. The product gas mixture along with unreacted propane goes to a compressor 210 and subsequently to the cold section or cold box 202 where light gases are separated. The hydrogen from the light gases is then separated from the remaining light gases using a pressure swing adsorption unit 203. Hydrogen and the other light gases exit the dehydrogenation system 200 as stream 21 1 and are typically used as fuel gas.
The liquid from the cold box 202 is then sent to a de-ethaniser 204 where components lighter than propene (such as methane and ethane) are removed at the top for export (stream 213). Propene and the other heavier components are sent to a C3 splitter tower 205 where propene is obtained (stream 212).
The bottom stream of C3 splitter 205 is recycled back then together with freshly injected propane (stream 203) to the dehydrogenation reactor 201 .
Example 3:
Fig. 2A illustrates a first embodiment of the present process.
As in the conventional OCM process of Fig. 1 A ethane and oxygen enter the OCM reactor 101 . The OCM reactor effluent (stream 106) is fed into the C02 removal unit 1 10. Part of the removed C02 will be guided into the methanation unit, whereas the remaining C02 part is vented out of the system (not shown).
Next the OCM product stream is directed from the carbon dioxide removal unit 1 1 1 to further work up units. In a first step the OCM product stream enters as a demethanizer unit (De-C1 ) 1 14 which separates and recovers methane from higher molecular weight C2+ hydrocarbons
(such as ethane, ethene, propene). The recovered methane is fed to the methanation unit (not shown).
The C2+ hydrocarbon effluent is further directed from the demethanizer unit 1 14 to the deethanizer unit 1 18 for separating C2 hydrocarbons (such as ethane and ethene) from C3+ hydrocarbons. The separated C2 hydrocarbons are then transferred to a C2 splitter (not shown). The C3+ hydrocarbons (stream 120) leaving the deethanizer unit 1 18 in the OCM process are now transferred to a C3 splitter unit 205 in the propane dehydrogenation system.
In the propane dehydrogenation system propane is reacted to propene in the dehydrogenation reactor 201 . The reactor effluent is subsequently fed to a separation unit (not shown) for separating light gases and a deethanizer unit 204. The C3+ hydrocarbon effluent leaving the deethanizer unit 204 is guided into a C3 splitter for separating propane and propene. The separated propene stream 212 consists essentially of polymer grade propene (PG propene). The OCM process and the dehydrogenation system are thus combined such that C3 hydrocarbon stream 120a as side product in the OCM process is tunneled into the C3 splitter in the dehydrogenation process. This allows for providing high value propane.
Example 4
Fig. 2B illustrates a second embodiment of the present process. Reference is made to the schemes shown in Figs. 1 A, 1 B and 1 C.
Here, the C3 hydrocarbon stream 120a leaving the depropanizer unit 123 in the OCM process are tunneled to the C3 splitter 205 in the propane dehydrogenation process.
As a result the amount of fresh propane (C3 LPG feed stream 203) that is required can be reduced by 20,7 kg per tonne OCM ethylene capacity. Moreover, the amount of polymer grade propene (stream 212) that can be obtained is increased by 39,1 kg per tonne OCM ethylene capacity. Besides, the OCM refinery grade propylene product is upgraded into polymer grade propylene and propane.
Example 5 Fig. 3A illustrates a third embodiment of the present process.
As in the conventional OCM process of Fig. 1 A ethane and oxygen enter the OCM reactor 101 . The OCM reactor effluent (stream 106) is fed into the C02 removal unit 1 10. Part of the removed C02 will be guided into the methanation unit, whereas the remaining C02 part is vented out of the system (not shown). Next the OCM product stream is directed from the carbon dioxide removal unit 1 10 to further work up units. In a first step the OCM product stream enters as a demethanizer unit (De-C1 ) 1 14 which separates and recovers methane from higher molecular weight C2+ hydrocarbons (such as ethane, ethene, propene). The recovered methane is fed to the methanation unit (not shown).
The C2+ hydrocarbon effluent from the demethanizer unit 1 14 in the OCM system is now directed to the deethanizer unit 204 as part of the propane dehydrogenation system for separating C2 hydrocarbons (such as ethane and ethene) from C3+ hydrocarbons.
The separated C2 hydrocarbon stream 213 from the deethanizer unit 204 in the dehydrogenation system is then transferred back into the OCM system, more particular to the C2 splitter 121 . In the C2 splitter 121 ethane and ethene are separated from each other. While ethene is used for further purposes such as for polymerisation, ethane (stream 105) is recycled back to the cracking unit of the OCM reactor 101 .
In the propane dehydrogenation system propane is reacted to propene in the dehydrogenation reactor 201 . The reactor effluent is subsequently fed to a separation unit (not shown) for separating light gases and a deethanizer unit 204. The C3+ hydrocarbon effluent leaving the deethanizer unit 204 is guided into a C3 splitter for separating propane and propene. The separated propene stream 212 consists essentially of polymer grade propene (PG propene). The OCM process and the dehydrogenation system are thus combined such that C2+ hydrocarbon stream from the OCM process is tunneled into the deethanizer unit in the dehydrogenation process and after separating off the C3+ hydrocarbons the C2 hydrocarbons are tunneled back into the OCM system. This allows the use of one common deethanizer unit 204 for both processes.
Example 6
Fig. 3B illustrates a fourth embodiment of the present process. Reference is made to the schemes shown in Figs. 1 A, 1 B and 1 C.
Here, the C2+ hydrocarbon effluent from the demethanizer unit 1 14 in the OCM process is fed into the dehydrogenation process, specifically into the deethanizer unit 204 in the dehydrogenation process. The separated C2 hydrocarbon stream 213 from the deethanizer unit 204 in the dehydrogenation system is then transferred back into the OCM system, more particular to the C2 splitter 121 . In the 02 splitter 121 ethane and ethene are separated from each other. While ethene is used for further purposes such as for polymerisation, ethane (stream 105) is recycled back to the cracking unit of the OCM reactor 101 . OCM ethylene production capacity is increased by 9,3 kg per tonne PDH propylene capacity and OCM fresh ethane feed is decreased by 83,3 kg per tonne PDH propylene capacity.
Besides, a de-ethaniser is no longer required in the OCM process.

Claims

An integrated process for producing C2+ hydrocarbons preferably C2+ saturated and unsaturated hydrocarbons, comprising a process for oxidative coupling of methane (OCM) which comprises the steps of
- producing C2+ hydrocarbons from methane and at least one oxidizing agent, preferably oxygen, and from ethane in at least one OCM reactor (101 ) comprising at least one OCM catalyst unit and at least one cracking unit,
- transferring at least one OCM effluent (106) from the at least one OCM reactor (101 ) to at least one fractionation system for separating the C2+ hydrocarbons in one or more hydrocarbon product streams, wherein the fractionation system comprises at least one demethanizer unit (1 14) for separating methane from C2+ hydrocarbons, and
at least one C2 splitter unit (121 ) for separating ethane and ethene, and/or
at least one deethaniser unit (1 18) for separating C2 hydrocarbons, from C3+ hydrocarbons, and a propane dehydrogenation process which comprises the steps of
- producing propene from propane in at least one dehydrogenation reactor (201 ),
- transferring at least one dehydrogenation reactor effluent from the at least one dehydrogenation reactor (201 ) to at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit (204) for separating C2 hydrocarbons,, from C3+ hydrocarbons, and at least one C3 splitter unit (205) for separating propane and propene, characterized in that the C3+ hydrocarbon effluent (120) from the at least one deethanizer unit (1 18) in the OCM process is fed into the at least one 03 splitter unit (205) in the propane dehydrogenation process, and/or the C2+ hydrocarbon effluent from the at least one demethanizer unit (1 14) in the OCM process is fed into the at least one deethanizer unit (204) in the propane dehydrogenation process and the C2 hydrocarbon effluent (213) from the at least one deethanizer unit (204) in the propane dehydrogenation process is fed to the at least one C2 splitter unit (121 ) in the OCM process.
2. Process according to claim 1 , characterized in that the OCM reactor effluent is fed to at least one compression unit (107) that is arranged downstream of the OCM reactor (101 ) before entering the at least one fractionation system.
3. Process according to at least one of the preceding claims, characterized in that the OCM reactor effluent (106) is fed to at least one C02 removal unit (1 10) that is arranged downstream of the OCM reactor (101 ) and the compression unit (107) before entering the at least one fractionation system.
4. Process according to at least one of the preceding claims, characterized in that the methane separated in the demethanizer unit (1 14) is fed to at least one methanation unit (1 1 1 ) and further recycled back into the OCM reactor (101 ).
5. Process according to one of the preceding claims, characterized in that the C2+ hydrocarbon effluent leaving the demethanizer unit (1 14) is fed into at least one deethanizer unit (1 18) for separating C2 hydrocarbonsfrom C3+ hydrocarbons.
6. Process according to one of the preceding claims, characterized in that the C2 hydrocarbon effluent (213) leaving the at least one deethanizer unit (204) and that is fed to the at least one C2 splitter unit (121 ) comprises ethane, ethene and further methane.
7. Process according to one of the preceding claims, characterized in that the ethane (105) leaving the at least one C2 splitter unit (121 ) is recycled back to the OCM reactor (101 ), preferably to the cracking unit of the OCM reactor.
8. Process according to one of the preceding claims, characterized in that the dehydrogenation reactor effluent is transferred to at least one separation unit comprising at least one cold box unit (202) and at least one pressure swing adsorption unit (203) arranged downstream of the propane dehydrogenation reactor (201 ) before entering the at least one fractionation system.
9. Process according to one of the preceding claims, characterized in that the effluent of the at least one C3 splitter unit (205) is fed into at least one depropanizer unit (207) as part of the dehydrogenation process for separating propane from C4+ hydrocarbons.
10. Process according to claim 9, characterized in that the propane leaving the at least one de-propanizing unit (207) is recycled back into the propane dehydrogenation reactor (201 ).
1 1 . An integrated process system for conducting a process for producing C2+ hydrocarbons according to one of the preceding claims comprising at least one OCM system comprising
- at least one OCM reactor (101 ) comprising at least one OCM catalyst unit for generating C2+ hydrocarbons from methane and at least one cracking unit for generating C2+ hydrocarbons, preferably ethene, from ethane;
- at least one fractionation system for separating the C2+ hydrocarbons in one or more desired hydrocarbon products streams, wherein the fractionation system comprises
at least one demethanizer unit (1 14) for separating methane from C2+ hydrocarbons, and at least one C2 splitter unit (121 ) for separating ethane and ethene, and/or
at least one deethanizer unit (1 18) for separating C2 hydrocarbons from C3+ hydrocarbons, and at least one propane dehydrogenation system comprising
- at least one propane dehydrogenation reactor (201 ) for producing propene from propane,
- at least one fractionation system for separating propene from the reactor effluent, wherein the fractionation system comprises at least one deethanizer unit (204) for separating C2 hydrocarbons, , from C3+ hydrocarbons, and at least one C3 splitter unit (205) for separating propane and propene, characterized in that the at least one depropanizer unit (1 10) in the OCM system is in fluid connection to the at least one C3 splitter unit (205) in the propane dehydrogenation system for feeding the C3 hydrocarbon effluent from the at least one deethanizer unit (1 18) in the OCM system into the at least one C3 splitter unit (205) in the propane dehydrogenation system, and/or the at least one demethanizer unit (1 14) in the OCM system is in fluid connection to the at least one deethanizer unit (204) in the propane dehydrogenation system for feeding the C2+ hydrocarbon effluent from the demethanizer unit (1 14) in the OCM system into the deethanizer unit (204) in the propane dehydrogenation system and feeding the C2 hydrocarbon effluent from the at least one deethanizer unit (204) in the propane dehydrogenation system to the at least one C2 splitter unit (121 ) in the OCM process.
12. Process system according to claim 1 1 , characterized in that at least one at least one compression unit (107) and at least C02 removal unit (1 10) are arranged downstream of the OCM reactor (101 ) and upstream of the at least one fractionation system.
13. Process system according to one of the claims 1 1 to 12, characterized in that at least one methanation unit (1 1 1 ) is arranged downstream of the at least one demethanizer unit (1 14).
14. Process system according to one of the claims 1 1 to 13, characterized in that at least one deethanizer unit (1 18) is arranged downstream of the at least one demethanizer unit (1 14).
15. Process system according to one of the claims 1 1 to 14, characterized in that at least one separation unit comprising at least one cold box unit (202) and at least one pressure swing adsorption unit (203) arranged downstream of the propane dehydrogenation reactor (201 ).
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