Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
  • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
  • F25J3/0209—Natural gas or substitute natural gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
  • F25J3/0219—Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
  • F25J3/0238—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 2 carbon atoms or more
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
  • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
  • F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/08—Processes or apparatus using separation by rectification in a triple pressure main column system
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2205/00—Processes or apparatus using other separation and/or other processing means
  • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
  • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2210/00—Processes characterised by the type or other details of the feed stream
  • F25J2210/12—Refinery or petrochemical off-gas
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2215/00—Processes characterised by the type or other details of the product stream
  • F25J2215/62—Ethane or ethylene
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
  • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
  • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
  • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
• • 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
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• the invention relates to a method for recovery of methane from hydrocarbon streams and a system for recovery of methane from hydrocarbon streams.
• Methane is a very important natural gas which is used in a huge variety of different applications.
• One important use of methane is as a fuel, since burning methane produces less carbon dioxide for each unit of heat released in comparison with other hydrocarbon fuels.
• methane is supplied in the form of a liquefied natural gas (LNG) for storage and transportation purposes.
• LNG liquefied natural gas
• Another very important use of methane is the application of methane as a reactant in a technical synthesis.
• Methane is an important starting material, for example, for the technical synthesis of hydrogen, methanol, ethylene, hydrogen cyanide, methyl halogenides, or organic compounds.
• reaction mixture a synthetic gas mixture comprising different reaction products, unreacted starting materials and, optionally, other compounds which were introduced during the reaction process, but did not participate in the reaction itself.
• reaction mixture a synthetic gas mixture
• Different methods have been developed in order to separate the target product, or the target products, from the reaction mixture.
• demethaniser is applied in order to separate methane and other hydrocarbon-free compounds (e.g. hydrogen or nitrogen) from the remaining hydrocarbon compounds in the reaction mixture, which comprise a carbon content of C 2 or higher.
• hydrocarbon-free compounds e.g. hydrogen or nitrogen
• the use of a demethaniser system on a synthetic gas mixture aims at the separation of methane and other hydrocarbon-free gases from a reaction mixture in order to facilitate a further subsequent separation step of the now methane-free hydrocarbon fraction comprising hydrocarbons with a carbon content of C 2 or higher.
• the thus separated methane content is generally discharged or has to be further processed in order to be used for any further process or synthesis.
• US 2013/225884A1 discloses processes for producing and separating ethane and ethylene, wherein an oxidative coupling of methane (OCM) product gas comprising ethane and ethylene is introduced to a separation unit comprising two separators. Within the separation unit, the OCM product gas is separated to provide a C 2 -rich effluent, a methane-rich effluent, and a nitrogen-rich effluent.
• OCM methane
• the method of the invention for the recovery of methane from hydrocarbon streams comprises the following steps: a. introducing a feed fluid stream, which comprises a methane fluid, at least one hydrocarbon-free fluid, wherein in particular said at least one hydrocarbon-free fluid is nitrogen, and at least one hydrocarbon fluid, into a demethaniser system;
• a carbon-rich fraction which comprise hydrocarbons with a carbon content of C 2 and higher, and
• a separation stream which comprises methane fluid and at least one hydrocarbon-free fluid
• a hydrocarbon-free fluid separation system in particular in a cryogenic hydrocarbon-free fluid separation system, more particularly into a cryogenic nitrogen rejection system; wherein preferably said separation stream is compressed by a compressor system before said separation stream is introduced in said hydrocarbon-free fluid separation system, wherein preferably said separation stream is compressed to a pressure of 25 bar to 80 bar; d. Separating said separation stream in said free fluid separation system into a methane stream and a hydrocarbon-free fluid stream.
• the method of the invention allows the provision of an essentially pure methane stream and a good separation of said methane stream from the feed fluid stream, which may be used in a reaction process for further products.
• feed fluid stream is to be understood as a liquid and/or a gas stream comprising liquid or gaseous methane, liquid or gaseous hydrocarbon compounds, and/or a hydrocarbon-free fluid in liquid and/or gaseous form.
• hydrocarbon compounds is to be understood as compounds with a carbon content of C 2 or higher which comprise at least one hydrogen-carbon bond. Such hydrocarbon compounds are particularly alkane or alkene compounds like ethane, ethane (ethylene), propane or propene (propylene) and the like.
• hydrocarbon-free fluid is to be understood as a compound in a liquid or a gaseous form which comprises no hydrogen-carbon bond, such as hydrogen, nobel gases, CO, C0 2 , or nitrogen.
• a hydrocarbon-free fluid is particularly argon, CO, hydrogen or nitrogen, more particularly nitrogen.
• said feed fluid stream derives from a synthesis system which uses methane as a reactant.
• synthesis systems may be a system designated for the oxidative coupling of methane (OCM) or a methane pyrolysis.
• OCM oxidative coupling of methane
• methane pyrolysis a methane pyrolysis
• the synthesis system is a system designated for the oxidative coupling of methane (OCM).
• the oxidative coupling of methane is a known chemical reaction (OCM reaction) applied to the conversion of methane into further chemicals, in particular into ethan, ethylene, C3- hydrocarbons or C4- hydrocarbons, more particularly ethylene.
• OCM reaction chemical reaction
• the reaction is generally carried out in the presence of a catalyst and comprises several reaction and separation steps for producing ethylene from a methane feed.
• the methane feed is generally mixed with compressed air and comprises after the reaction with the catalyst nitrogen, methane, CO, C0 2 , hydrocarbons with a carbon content of C 2 or higher (e.g. ethan, ethylene, C3- hydrocarbons or C4- hydrocarbons), and water.
• the principle product of OCM is ethylene, the world's largest commodity chemical, and the fundamental building block of the chemical industry.
• methane activation is difficult owing to its thermodynamic properties. This limits the efficient utilisation of methane, an important petrochemical resource.
• the application of a catalyst in the reaction system and the adjustment of the reaction conditions have improved the conversion of methane in an OCM reaction.
• the products of OCM reactions - depending on the reaction conditions - may react to undesired by-products.
• a low conversion of methane is used. Thus, a significant amount of unreacted methane is left in the reaction mixture.
• said methane stream is recycled and reused as a reaction product in a technical synthesis.
• the feed fluid stream is derived from a synthesis system, which uses methane as a reactant and said feed fluid stream is separated in said
• demethaniser system into said carbon-rich fraction and said separation stream, wherein said separation stream is introduced into said hydrocarbon-free fluid separation system, in particular in said cryogenic hydrocarbon-free fluid separation system, more particularly into said cryogenic nitrogen rejection system, and wherein said separation stream is separated in said hydrocarbon-free fluid separation system into a methane stream and a hydrocarbon-free stream.
• the feed fluid stream is derived from a synthesis system designated for an OCM reaction and said feed fluid stream is separated in said demethaniser system into said . carbon-rich fraction and said separation stream, wherein said separation stream is introduced into said nitrogen rejection system, in which said separation stream is separated into a methane stream and a nitrogen stream.
• said separation stream is compressed by said compressor system before said separation stream is introduced in said hydrocarbon-free fluid separation system, wherein in particular said separation stream is compressed to a pressure of 25 bar to 75 bar, preferably to a pressure of 25 bar to 60 bar, more preferably to a pressure of 25 to 40 bar, more preferably to a pressure of 30 to 40 bar, particularly to a pressure of 30 bar.
• the boundaries of the above pressure ranges may also be combined in an arbitrary fashion.
• the lower pressure boundary of these pressure ranges may also be one of: 12 bar, 13 bar, 14 bar, 15 bar, 16 bar, 17 bar, 18 bar, 19 bar, 20 bar, 21 bar, 22 bar, 23 bar, 24 bar, 25 bar, 26 bar, 27 bar, 28 bar, 29 bar.
• the compression of the separation stream after leaving this demethaniser system and before the introduction into the hydrocarbon-free fluid separation system allows for a better separation and isolation of methane and hydrocarbon-free gas, in particular nitrogen, from the separation stream as in comparison to a direct introduction of the separation stream from the demethanizer system into the hydrocarbon-free fluid separation system.
• a lower pressure is preferred in the demethaniser system, since the increase of pressure in the demethaniser would lead to higher hydrocarbon product losses.
• a compressor system in particular of a 3-step compressor system (e.g. a compressor system described in the document WO02/088612A1) allows for a compensation of the preferably lower pressure in the demethaniser system and allows the separation of the separation stream in the hydrocarbon-free fluid separation system at a higher pressure.
• the separation stream derived from the compressor is cooled down, in particular the separation stream is cooled down in a plate fin heat exchanger, and expanded to a lower pressure, before said separation stream is introduced into the hydrocarbon-free fluid separation system.
• said carbon-rich fraction from the demethaniser system is transferred to a C2-splitter in which hydrocarbons with different carbon contents of said carbon-rich fraction are separated from each other.
• the use of a C2-splitter allows separation and isolation of target products from the carbon-rich fraction.
• C2-splitters are known in the art, and the dimensions and separation conditions depend on the target compound, which depends in itself on the previously-applied synthesis system, which provides the feed fluid stream.
• the C2-splitter is designed and operated in such a way that the target compound ethylene can be separated in high purity. If the separated methane stream (as described previously) is recycled and reintroduced into the OCM reaction system (synthesis system), the target compound ethylene could be achieved in a more cost-effective way, since the (nowadays restricted) natural resource methane is used more efficiently.
• said carbon rich fraction of the demethanizer system is reboiled in a reboiler, in particular said carbon rich fraction of the demethanizer system is reboiled before said carbon rich fraction is transferred to said C2-splitter.
• At least parts of the feed fluid stream are liquidized in a cooling system before the introduction into a demethaniser unit of said demethaniser system.
• the demethaniser unit is designed to separate methane and the hydrocarbon-free fluid, in particular nitrogen, from the hydrocarbons with a carbon content of C 2 or higher from the reaction mixture derived from the reaction system.
• a demethaniser unit may be for example a distillation column.
• said feed fluid stream is separated in said cooling system into a liquid feed fluid stream and a gaseous feed fluid stream, wherein said liquid feed fluid stream is transferred to said demethaniser unit and said gaseous feed fluid stream is transferred to a (first) expander booster system, in which said gaseous feed fluid stream is expanded to a lower pressure before introducing into said demethaniser unit.
• a (first) expander booster system in which said gaseous feed fluid stream is expanded to a lower pressure before introducing into said demethaniser unit.
• liquid feed fluid stream from the cooling system and the gaseous feed fluid stream from the (first) expander booster system are combined in said demethaniser unit and separated in the demethaniser unit into a carbon-rich fraction and separation stream. After the separation the separation stream is
• said gases feed fluid stream is introduced into a first expander booster system in which said gases feed fluid stream is expanded to a lower pressure before introducing into said demethaniser unit.
• said separation stream from said demethaniser unit is introduced in the second expander booster system in which it is expanded to provide said chilling duty. Additionally, the work power of both expanders is recovered to recompress the separation stream, in particular to recompress the separation stream to approximately 6 bar, before said separation stream is introduced into said hydrocarbon-free fluid separation system.
• the demethaniser system is operated at a pressure of 6 to 40 bar.
• the demethaniser unit of said demethaniser system is operated at a pressure of 9 to 25 bar, in particular at a pressure of approximately 13 bar. In some embodiments the demethaniser unit is operated at a temperature range of -20 to -170 °C. In some embodiments, the demethaniser unit comprises a degrading temperature range along its longitudinal axis, wherein in particular the demethaniser unit comprises a temperature of - 30 °C at the bottom of the demethaniser unit, and a temperature of approximately - 150 °C at the top of the demethaniser unit.
• said separation stream is introduced in at least one high- pressure column arranged in said hydrocarbon-free fluid separation system, in which said separation stream is separated in a methane-rich bottom liquid and an essentially pure gaseous hydrocarbon-free overhead, wherein said methane-rich bottom liquid is transferred into at least one low-pressure column arranged in said hydrocarbon-free fluid separation system, in which said methane-rich bottom liquid is separated in hydrocarbon-free gas and a methane-rich liquid fraction.
• the methane-rich liquid fraction is at least partially vaporized - providing a liquid fraction and a methane gas fraction - wherein the cold derived from said liquid methane gasification is used for the separation process.
• the low-pressure hydrocarbon-free gas fraction and the liquid fraction - derived from the partial vaporization of said methane-rich bottom liquid - are used to cool the inlet streams of both columns.
• said methane-rich bottom liquid is transferred to the mid part of said low-pressure column.
• said methane-rich bottom liquid and said gaseous hydrocarbon- free overhead are sub cooled in a cooler, particularly a reflux cooler, to approximately - 160 °C before they are transferred to said low-pressure column.
• said hydrocarbon-free overhead from the high-pressure column is at least partially condensed and said bottom liquid from the low-pressure column is at least partially vaporised on a heat exchanger, in particular on a heat exchanger which is arranged between said high-pressure column and said low-pressure column.
• said at least one high-pressure column and said at least one low-pressure column are integrated in one unit, wherein said at least one high- pressure column and said at least one low-pressure column are interconnected with a heat exchanger situated between both columns.
• the feed fluid stream is provided from an OCM reaction system, thus comprising a very high content of nitrogen and a
• the method of the invention allows firstly the separation and isolation of the methane and nitrogen mixture (separation stream) from the reaction mixture of the OCM reaction (the feed fluid stream) in said demethaniser system, and secondly the separation from each other in said cryogenic nitrogen rejection system in a very high purity.
• the gaseous methane can be recycled and reused in the OCM reaction system.
• said high-pressure column is operated at a pressure of 6 to 40 bar, in particular at a pressure of approximately 20 bar, and a temperature of -160 to -90 °C, in particular at a temperature of approximately -140 °C, and wherein said low- pressure column is operated at a pressure of 1 to 5 bar, in particular at a pressure of approximately 2 bar, and a temperature of -220 to -180 °C, in particular at a
• the invention comprises a system for recovery of methane from hydrocarbon streams comprising:
• a demethaniser system which is designated to separate a feed fluid stream, which comprises methane fluid, at least one hydrocarbon-free fluid, wherein in particular said at least one hydrocarbon-free fluid is nitrogen, and at least one hydrocarbon fluid, into
• a separation stream which comprises methane fluid and at least one hydrocarbon-free fluid
• hydrocarbon-free fluid separation system more particularly a cryogenic nitrogen rejection system, which is designated to separate said separation stream into a methane stream and a hydrocarbon-free stream;
• a compressor system that is configured to compress said separation stream to a pressure of 12 bar to 80 bar upstream said hydrocarbon-free fluid separation system.
• the compressor system is configured to compress said separation stream to a pressure of 15 bar to 75 bar, preferably to a pressure of 20 bar to 60 bar, more preferably to a pressure of 25 bar to 40 bar, more preferably to a pressure of 30 bar to 40 bar, particularly to a pressure of 30 bar, before said separation stream is introduced in said hydrocarbon-free fluid separation system.
• the boundaries of these pressure ranges may also be combined in an arbitrary fashion.
• the lower pressure boundary of these pressure ranges may also be one of: 12 bar, 13 bar, 14 bar, 15 bar, 16 bar, 17 bar, 18 bar, 19 bar, 20 bar, 21 bar, 22 bar, 23 bar, 24 bar, 25 bar, 26 bar, 27 bar, 28 bar, 29 bar.
• the system of the invention comprises a synthesis system, which uses methane as a reactant and provides said feed fluid stream, wherein in particular said synthesis system is a system for oxidated coupling of methane (OCM), wherein in particular the system comprises means to transfer the recovered and isolated methane from the hydrocarbon-free fluid separation system to the synthesis system.
• OCM oxidated coupling of methane
• Figure 1 shows a first embodiment of the invention comprising a demethaniser system 1 and a hydrocarbon-free fluid separation system 2; and
• Figure 2 shows a second embodiment of the invention comprising a
• demethaniser system 1 demethaniser system 1 , a cryogenic nitrogen rejection system 2", and an OCM synthesis system 3.
• Figure 1 shows a system for recovery of methane from hydrocarbon streams
• a feed fluid stream F comprising methane fluid, at least one hydrocarbon-free fluid, and at least one hydrocarbon fluid is introduced into a demethaniser unit 10 of the demethaniser system 1.
• the demethaniser unit 10 is operated at a pressure of 13 bar. Different pressures may be applied as necessary.
• the demethaniser unit 10 comprises a temperature gradient with a temperature of - 30 °C at the bottom of the demethaniser unit 10 and a temperature of approximately - 150 °C at the top of the demethaniser unit 10.
• the demethaniser unit 0 allows for a separation of the feed fluid stream F into a carbon-rich fraction C at the bottom of the demethaniser unit 10, and a separation stream S, which comprises methane fluid and at least one hydrocarbon-free fluid, in particular nitrogen, at the top of the demethaniser unit 10.
• the feed fluid stream F may be cooled down with at least one cooling system (not depicted in the figure), wherein each separated liquid of each cooling step (liquid feed stream) is introduced into the demethaniser 10.
• a remaining gaseous feed stream may be transferred from the cooling systems into an expander boost system (not depicted in the figure), in which it is expanded to a lower pressure and subsequently introduced into the demethaniser unit 10.
• the carbon-rich fraction C from the bottom of the demethaniser 10 is reboiled in a reboiler 4 in order to provide a carbon-rich fraction C, which is free of methane and hydrocarbon-free fluids like nitrogen.
• the carbon-rich fraction C is then transferred to a C2 splitter 7 for further separation in order to isolate the target product from the carbon- rich fraction C.
• the target product is ethylene if the feed fluid stream F is derived from a synthesis system 3 (see figure 2), which applies the oxidative methane- coupling reaction (OCM).
• the separation stream S is then transferred from the top of the demethaniser unit 10 to the hydrocarbon-free fluid separation unit 2.
• the separation stream S may be transferred - prior to the introduction to the hydrocarbon-free fluid separation system 2 - into a second expander (not depicted), where it is expanded to approximately 4 bar, providing the chilling duty used in the demethaniser system.
• the work power of the first and the second expander can be recovered in order to recompress the separation stream S to approximately 6 bar, before it is introduced into the hydrocarbon-free fluid separation system 2.
• the hydrocarbon-free fluid separation system 2 comprises a high-pressure column 21 and a low-pressure column 22, which are interconnected with a heat exchanger 5 situated between the high-pressure column 21 and the low-pressure column 22.
• the separation stream S Before the separation stream S is introduced into the bottom of the high-pressure column 21 it may be cooled down by, for example, a plate fin heat exchanger.
• the high-pressure column 21 and the low-pressure column 22 can be constructed as separate columns.
• the separation stream S is separated into a methane- rich bottom liquid at the bottom of the high pressure column 21 and a gaseous stream, comprising essentially pure hydrocarbon-free overhead product, in particular an essentially pure nitrogen overhead product.
• the pressure at the bottom of the high- pressure column 21 is approximately 20 bar, and the temperature is approximately - 140 °C.
• the bottom liquid from the bottom of the high pressure column 21 is transferred to the mid-section of the upper low-pressure column 22.
• the bottom liquid may be sub-cooled in a reflex cooler to approximately - 160 °C before it is transported to the mid-section of the low-pressure column 22.
• the low- pressure column 22 operates at a pressure of 2 bar, which allows for a further separation of hydrocarbon-free gas, in particular nitrogen, and methane, due to their physical properties.
• the hydrocarbon-free product HF in particular nitrogen, can be sent to the
• Figure 2 shows a system for recovery of methane from hydrocarbon streams comprising a demethaniser system 1 , a cryogenic nitrogen rejection system 2"and a synthesis system 3, which uses methane in an OCM reaction. Concerning the description and the features of functions or applications with the same numbering or letter, reference is made to the description of Figure 1.
• the system for recovery of methane from hydrocarbon streams is essentially the same as in Figure 1 .
• the feed fluid stream F derives from a synthesis system 3 which uses methane as a reactant in an OCM reaction.
• the separation stream S comprises essentially methane and nitrogen.
• the separation stream S is compressed with a compression system 6 to approximately 25 bar to 80 bar, preferably to a pressure of 25 bar to 75 bar, preferably to a pressure of 25 bar to 60 bar, more preferably to a pressure of 25 to 40 bar, in particular to 30 bar.
• a compression system 6 to approximately 25 bar to 80 bar, preferably to a pressure of 25 bar to 75 bar, preferably to a pressure of 25 bar to 60 bar, more preferably to a pressure of 25 to 40 bar, in particular to 30 bar.
• the other pressure ranges stated above may also be used.
• a cryogenic nitrogen rejection system 2 provides a very good separation and isolation of nitrogen and methane, if it is operated with a high pressure.
• the demethaniser system 1 is preferably operated at a lower pressure in order to minimise product losses concerning the main product ethylene (derived from the OCM reaction).
• a compressor system 6 in order to provide a separation stream S with a higher pressure compared to the situation in the
• demethanizer system 1 compensates for these deficiencies.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• Thermal Sciences (AREA)
• General Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Separation By Low-Temperature Treatments (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=51260559

Family Applications (1)

Country Status (11)

Families Citing this family (2)

Family Cites Families (8)

• 2015
  • 2015-07-23 AU AU2015295882A patent/AU2015295882A1/en not_active Abandoned
  • 2015-07-23 EP EP15747094.9A patent/EP3175190A1/en not_active Withdrawn
  • 2015-07-23 US US15/329,705 patent/US20170219281A1/en not_active Abandoned
  • 2015-07-23 CN CN201580039506.6A patent/CN106574818A/zh active Pending
  • 2015-07-23 CA CA2954549A patent/CA2954549A1/en not_active Abandoned
  • 2015-07-23 EA EA201692570A patent/EA201692570A1/ru unknown
  • 2015-07-23 WO PCT/EP2015/001518 patent/WO2016015849A1/en active Application Filing
  • 2015-07-23 BR BR112017001493A patent/BR112017001493A2/pt not_active Application Discontinuation
  • 2015-07-23 MX MX2017001188A patent/MX2017001188A/es unknown
  • 2015-07-23 JP JP2017504176A patent/JP2017523179A/ja active Pending
• 2017
  • 2017-01-03 PH PH12017500008A patent/PH12017500008A1/en unknown

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events