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• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B23/00—Noble gases; Compounds thereof
• • 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
  • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
  • F25J3/0605—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the feed stream
  • F25J3/061—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
  • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
  • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
  • F25J3/066—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation 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
  • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
  • F25J3/06—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation
  • F25J3/063—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream
  • F25J3/0685—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases
  • F25J3/069—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by partial condensation characterised by the separated product stream separation of noble gases of helium
• • 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
  • F25J3/08—Separating gaseous impurities from gases or gaseous mixtures or from liquefied gases or liquefied gaseous mixtures
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0001—Separation or purification processing
  • C01B2210/0003—Chemical processing
  • C01B2210/0004—Chemical processing by oxidation
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0001—Separation or purification processing
  • C01B2210/0009—Physical processing
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0001—Separation or purification processing
  • C01B2210/0009—Physical processing
  • C01B2210/0014—Physical processing by adsorption in solids
  • C01B2210/0021—Temperature swing adsorption
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0029—Obtaining noble gases
  • C01B2210/0031—Helium
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0046—Nitrogen
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0053—Hydrogen
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
  • C01B2210/00—Purification or separation of specific gases
  • C01B2210/0043—Impurity removed
  • C01B2210/0068—Organic compounds
  • C01B2210/007—Hydrocarbons
• • 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
  • F25J2205/40—Processes or apparatus using other separation and/or other processing means using hybrid system, i.e. combining cryogenic and non-cryogenic separation techniques
• • 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
  • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
• • 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
  • F25J2205/82—Processes or apparatus using other separation and/or other processing means using a reactor with combustion or catalytic reaction
• • 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
  • F25J2210/04—Mixing or blending of fluids with the feed stream
• • 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
  • F25J2210/42—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
  • F25J2210/00—Processes characterised by the type or other details of the feed stream
  • F25J2210/62—Liquefied natural gas [LNG]; Natural gas liquids [NGL]; Liquefied petroleum gas [LPG]
• • 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
  • F25J2215/04—Recovery of liquid products
• • 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
  • F25J2215/30—Helium
• • 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
  • F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
  • F25J2230/30—Compression of the feed stream
• • 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
  • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
  • F25J2245/02—Recycle of a stream in general, e.g. a by-pass stream
• • 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
  • F25J2260/00—Coupling of processes or apparatus to other units; Integrated schemes
  • F25J2260/20—Integration in an installation for liquefying or solidifying a fluid stream
• • 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
  • F25J2270/00—Refrigeration techniques used
  • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
  • F25J2270/904—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by liquid or gaseous cryogen in an open loop

Definitions

• the present invention relates to a process for producing helium from a source gas stream comprising at least helium, methane, nitrogen and hydrogen.
• Helium is obtained commercially almost exclusively from a mixture of volatile components of natural gas, this mixture comprising, as well as helium, typically methane and nitrogen and traces of hydrogen, argon and other noble gases.
• this mixture comprising, as well as helium, typically methane and nitrogen and traces of hydrogen, argon and other noble gases.
• helium is made available as a component of the gas that accompanies mineral oil, or as part of the production of natural gas. It is theoretically possible to obtain helium in the atmosphere, but it is not economical because of the low concentrations (typical concentration of helium in the air of the order of 5.2 ppmv).
• the concentration of impurities in the helium stream to be liquefied must not exceed a value of 1000 ppm by volume, preferably 10 ppmv.
• the liquefaction process of helium is connected downstream of a helium purification process.
• This is generally composed of a combination of cryogenic processes, generally based on partial condensation, and adsorption processes, the regeneration in the case of the latter being possible due to the variation of temperature and or pressure.
• a process for purifying helium such that, in addition to the purified helium, nitrogen of requisite purity - in which the sum of the impurities is less than 1% by volume - can be obtained.
• nitrogen of requisite purity - in which the sum of the impurities is less than 1% by volume - can be obtained.
• only a portion, typically from 5% to 70%, preferably from 10% to 50%, of the nitrogen present in the mixture to be purified is brought to the desired purity.
• the remaining nitrogen is released into the atmosphere along with methane as a low pressure gas, either directly or after an oxidation step, preferably carried out in a torch or incinerator.
• This process for obtaining a pure helium fraction from a starting fraction comprising at least helium, methane and nitrogen comprises the following successive stages:
• the starting fraction is subjected to a methane and nitrogen removal
• step c) the compressed fraction is subjected to nitrogen removal, and d) the helium-rich fraction obtained in step c) is subjected to adsorption purification to produce a fraction.
• this method does not make it possible to treat gas streams containing a high hydrogen content, typically more than 6% by volume of hydrogen.
• FIG. 1 Another type of helium purification process known from the prior art is illustrated in FIG.
• a gaseous stream 1 ' comprising nitrogen, methane, helium and hydrogen, for example originating from the outlet of a nitrogen rejection unit (NRU) 15 following the treatment of a stream of natural gas to remove nitrogen from this natural gas, is introduced into a compressor 2 '. Once this gas is compressed, it is introduced into a 3 'helium concentrator device.
• NRU nitrogen rejection unit
• the hydrogen contained in the gas stream is removed by means of a system 4' in which hydrogen and oxygen react.
• the gas stream is then purified by means of an alternating pressure adsorption (PSA) process.
• PSA alternating pressure adsorption
• a gas stream 6 'from PSA 6' containing predominantly helium is then liquefied in a helium liquefaction device 7 '.
• the liquefied helium is sent to an 8 'helium storage system.
• liquid nitrogen stored in the device 10 ' is used to feed the helium concentrator device 3'.
• the gaseous stream 12 'containing a majority of nitrogen and a small amount of helium is purified by means of a purification means 13' eliminating the impurities contained in the gas stream 12 'in order to produce a gaseous stream 14' of recycling sent to the compressor 2 'after having been mixed with the gas mixture the initial to be treated.
• a purge implemented at the 3 'helium concentrator contains methane. It must then be treated using a methane oxidation device to meet environmental requirements. It is necessary to have an air separation unit 11 '(in English ASU) which produces the liquid nitrogen to the specification compatible with the 8' helium storage (of the order of ppm of methane).
• the inventors of the present invention have then bridged a solution to solve the problems raised above.
• the subject of the present invention is a process for producing helium from a source gas stream comprising at least helium, methane, nitrogen and hydrogen, comprising at least the following successive stages:
• PSA pressure swing adsorption
• the subject of the present invention is: A process as defined above characterized in that the source gas stream comprises from 40% to 95% by volume of nitrogen, from 0.05% to 40% by volume of helium, from 50 ppmv to 5% by volume of methane and from 1% to 10% by volume of hydrogen, preferably from 5% by volume to 10% by volume of hydrogen.
• a process as defined above comprising a step prior to step a) of producing the source gas stream to be treated by means of a nitrogen extraction unit or a natural gas liquefaction unit, said unit producing a stream of liquid nitrogen implemented in step d) allowing the partial condensation of the stream from step c) to produce a stream of liquid nitrogen and a gas stream comprising predominantly helium.
• step a) is between Bara and Bara, preferably between Bara and Bara.
• a process as defined above characterized in that the stream of liquid nitrogen from step d) comprises more than 98.5% by volume of nitrogen.
• step b) consists in bringing the gas stream coming from step a) into contact with oxygen and a catalytic bed comprising particles of at least one selected metal. among copper, platinum, palladium, osmium, iridium, ruthenium and rhodium, supported by a chemically inert carrier with respect to carbon dioxide and water so as to react with methane and hydrogen with oxygen.
• a process as defined above characterized in that it comprises an additional step f) liquefaction of the helium from step e).
• a process as defined above characterized in that the liquid nitrogen from step d) cools the liquefied helium in step f).
• a plant for producing helium from a source gas mixture comprising methane, helium, hydrogen and nitrogen comprising at least one compressor directly receiving the source gas mixture, at least one means for removing hydrogen and methane, at least one nitrogen removal and helium concentration device, and at least one helium purification means located downstream of the nitrogen removal and helium concentration, characterized in that the means for removing hydrogen and methane is located downstream of said at least one compressor and upstream of the nitrogen removal device and helium concentration.
• An installation as defined above characterized in that it further comprises a helium liquefaction device downstream of the helium purification means.
• FIG. 2 illustrates an embodiment of a method according to the invention.
• a source gas stream 1 containing at least helium, nitrogen, hydrogen and methane is treated by a process of the present invention to produce a pure helium stream, typically containing more than 99.9% % by volume of helium.
• the source stream 1 comes for example from a unit 2 of nitrogen extraction (in English, nitrogen rejection unit, NRU) located downstream of a cryogenic unit for treating natural gas.
• the source current 1 is introduced into a compressor 3 making it possible to compress the gas stream 4 at a pressure of between 15 bara (absolute bar) and 35 bara, preferably between 20 bara and 25 bara.
• the temperature is the ambient temperature where the installation is located.
• the gas stream 4 is introduced into a unit 5 for eliminating hydrogen and methane.
• This unit 5 consists for example of one to several reactors in series containing a catalyst between grids. This catalyst is typically Pd / Al 2 O 3. A catalytic oxidation between oxygen and oxidants (hydrogen / methane) is created.
• a high hydrogen content at the inlet makes it possible to operate at a high temperature and to co-oxidize the methane (for example, with 2% of hydorgene, the temperature rises to about 200 ° C. which is not sufficient not to oxidize methane).
• the hydrogen and methane contained in the initial source stream 1 to be treated are oxidized by the oxygen of unit 5.
• This gas stream 6 comprises mainly nitrogen and helium.
• the outgoing gas (against ambient air or cooling water) is cooled before being sent to the adsorption unit 7. Part of the water then condenses directly in a condensate recuperator. Part of the heat produced can be recovered for use in another process
• the gaseous stream 6 is then treated in an adsorption unit 7, such as an alternating-temperature adsorption unit (TSA), in order to eliminate water and carbon dioxide from the gaseous stream 6.
• an adsorption unit 7 such as an alternating-temperature adsorption unit (TSA)
• TSA alternating-temperature adsorption unit
• a gaseous stream 8 essentially comprising nitrogen and helium (that is to say comprising less than 5 ppm by volume of methane, less than 1 ppm by volume of hydrogen, less than 0.1 ppm by volume of carbon dioxide and less than 0.1 ppm by volume of water).
• the gaseous stream 8 is treated in a unit 9 for purifying nitrogen and concentrating helium.
• This unit 9 comprises at least one heat exchanger in which the gas stream is cooled from ambient temperature (0 ° C - 40 ° C for example) to a temperature between -180 ° C and -195 ° C.
• the gaseous flow is for example introduced into a phase separator pot generating a liquid flow 10 and a gaseous stream 11.
• the liquid stream contains 98.8% by volume of nitrogen.
• This liquid flow 10 is sent to a storage device 12 of liquid nitrogen. It does not contain methane.
• the gaseous stream 11 contains from 80% by volume to 95% by volume of helium and from 5% by volume to 20% by volume of nitrogen. Stream 11 is sent to a helium purification unit 13.
• This purification unit 13 is for example an alternating pressure adsorption unit (in English PSA) and produces two streams. One 14, containing 99.9% by volume of helium and another containing the remainder of the elements (essentially nitrogen). The gas stream 15 is introduced into a compressor 16 and then mixed with the source gas stream 1 to be treated, this is a regeneration loop of the unit 13.
• the helium rich stream 14 may be supplied to a helium liquefaction unit 17 producing a liquid helium stream 18 directed to a storage device 19.
• the pure liquid nitrogen stored in the nitrogen storage device 12 can be used to maintain the temperature of the helium storage device 19.
• a stream of liquid nitrogen produced by the nitrogen extraction unit 2 is introduced into the unit 9 for purifying nitrogen and concentrating helium. This makes it possible to obtain the necessary cooling capacity and thereby avoid the investment of a dedicated air separation unit contrary to the process illustrated in FIG.
• Another refrigerant present at the site for example LNG
• a high pressure fluid can be used (by Thomson expansion or turbines) to create the necessary cold.
• the simultaneous oxidation of hydrogen and methane occurs before the helium concentration.
• the TSA 7 then operates under pressure which guarantees a better efficiency (a reduction of the necessary volume of adsorbents as well as a reduction of the heat consumption at the level of the regeneration heater).
• the purge from the cryogenic helium concentration unit 9 no longer contains methane (which has been oxidized beforehand).
• Liquid nitrogen without methane can therefore be produced from unit 9. It is sufficient to integrate this unit 9 with the Helium concentration unit 2 (NRU or natural gas liquefaction unit) to obtain the cooling capacity required. This avoids the investment of a dedicated air separation unit (ASU).
• ASU dedicated air separation unit
• a stream 21 previously expanded in the unit 9 containing nitrogen and helium is extracted from said unit 9 and then sent to a compressor 3 and / or 16.
• Helium from the expansion of the liquid nitrogen unit 9 is recycled to increase the percentage of helium produced.
• the stream 21 comprises between 40% and 50% by volume of helium and between 50% and 60% by volume of nitrogen.
• Helium 1 1 is preconcentrated at about 90% to PSA 13 (rather than
• waste gas pressure (in English (offgas) of the PSA 13 can also be reduced compared with that of the process illustrated in FIG. 1 since they can return directly to the compressor 16 without first going through a drying unit.

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• 2015
  • 2015-04-30 FR FR1553906A patent/FR3035656B1/fr active Active
  • 2015-10-01 EA EA201792303A patent/EA035014B1/ru not_active IP Right Cessation
  • 2015-10-01 WO PCT/FR2015/052633 patent/WO2016174317A1/fr active Application Filing
  • 2015-10-01 US US15/742,146 patent/US20180238618A1/en not_active Abandoned

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