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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
  • F25J1/0229—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock
  • F25J1/0231—Integration with a unit for using hydrocarbons, e.g. consuming hydrocarbons as feed stock for the working-up of the hydrocarbon feed, e.g. reinjection of heavier hydrocarbons into the liquefied 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/0002—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the fluid to be liquefied
  • F25J1/0022—Hydrocarbons, e.g. 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/003—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production
  • F25J1/0047—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle
  • F25J1/0052—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the kind of cold generation within the liquefaction unit for compensating heat leaks and liquid production using an "external" refrigerant stream in a closed vapor compression cycle by vaporising a liquid refrigerant 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0211—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a multi-component refrigerant [MCR] fluid in a closed vapor compression cycle
  • F25J1/0214—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process using a multi-component refrigerant [MCR] fluid in a closed vapor compression cycle as a dual level refrigeration cascade with at least one MCR cycle
• • 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
  • F25J1/0235—Heat exchange integration
  • F25J1/0237—Heat exchange integration integrating refrigeration provided for liquefaction and purification/treatment of the gas to be liquefied, e.g. heavy hydrocarbon removal from natural gas
  • F25J1/0239—Purification or treatment step being integrated between two refrigeration cycles of a refrigeration cascade, i.e. first cycle providing feed gas cooling and second cycle providing overhead gas cooling
• • 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0228—Coupling of the liquefaction unit to other units or processes, so-called integrated processes
  • F25J1/0235—Heat exchange integration
  • F25J1/0237—Heat exchange integration integrating refrigeration provided for liquefaction and purification/treatment of the gas to be liquefied, e.g. heavy hydrocarbon removal from natural gas
  • F25J1/0239—Purification or treatment step being integrated between two refrigeration cycles of a refrigeration cascade, i.e. first cycle providing feed gas cooling and second cycle providing overhead gas cooling
  • F25J1/0241—Purification or treatment step being integrated between two refrigeration cycles of a refrigeration cascade, i.e. first cycle providing feed gas cooling and second cycle providing overhead gas cooling wherein the overhead cooling comprises providing reflux for a 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
  • F25J1/00—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures
  • F25J1/02—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures requiring the use of refrigeration, e.g. of helium or hydrogen ; Details and kind of the refrigeration system used; Integration with other units or processes; Controlling aspects of the process
  • F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
  • F25J1/0279—Compression of refrigerant or internal recycle fluid, e.g. kind of compressor, accumulator, suction drum etc.
  • F25J1/0292—Refrigerant compression by cold or cryogenic suction of the refrigerant 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
  • F25J3/0209—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
  • F25J3/0228—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
  • F25J3/0228—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
  • F25J3/0242—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 3 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
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/04—Processes or apparatus using separation by rectification in a dual 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
  • 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
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/74—Refluxing the column with at least a part of the partially condensed overhead 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
  • F25J2200/00—Processes or apparatus using separation by rectification
  • F25J2200/78—Refluxing the column with a liquid stream originating from an upstream or downstream fractionator column
• • 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
  • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
• • 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
  • F25J2205/50—Processes or apparatus using other separation and/or other processing means using absorption, i.e. with selective solvents or lean oil, heavier CnHm and including generally a regeneration step for the solvent or lean oil
• • 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
  • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
  • F25J2235/60—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being (a mixture of) 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
  • 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
  • F25J2270/00—Refrigeration techniques used
  • F25J2270/12—External refrigeration with liquid vaporising loop

Definitions

• the present invention relates to the field of liquefaction of natural gas.
• a raw natural gas mainly comprises methane, as well as various constituents such as water, sulphurous hydrogen, carbon dioxide, mercury, nitrogen and light hydrocarbons generally having between two and six carbon atoms.
• constituents such as water, sulphurous hydrogen, carbon dioxide and mercury, are pollutants that are removed upstream of the liquefaction stages of natural gas.
• Hydrocarbons heavier than methane are condensed and recovered as natural gas liquids that can be recovered.
• Natural gas liquids are separated from methane by means of a fractionation column and by cooling and partial liquefaction of the natural gas.
• the gas obtained at the top of the fractionation column is intended to be liquefied to produce the liquid natural gas.
• Operating at very high pressure limits the energy required for liquefaction.
• the operating pressure of the fractionation column is limited by the critical pressure of the mixture to be separated.
• the present invention aims to improve the recovery of propane and increase the critical pressure of the gas to be liquefied so as to achieve the fractionation at higher pressure, thus reducing the energy required for liquefaction.
• the invention involves recycling a stream of ethane into the reflux line of the fractionation column or into the reflux flask of the fractionation.
• the invention describes a method of liquefying a natural gas in which the following steps are carried out: a) partially liquefying the natural gas by cooling, b) introducing the partially liquefied natural gas into a fractionation column so as to obtain a gaseous fraction enriched in methane and a liquid fraction depleted in methane, c) cooling the gaseous fraction. until partial liquefaction, then the cooled gaseous fraction is introduced into a separator flask so as to separate a gaseous phase and a liquid phase, d) at least a portion of the liquid phase is recycled to the fractionation column as refluxing agent.
• step d) said part of the fraction enriched in ethane is mixed with said liquid phase, g) the gas phase obtained in step c) is liquefied by cooling and then by expansion so as to produce a liquid natural gas .
• the fraction enriched in ethane obtained in step e) may comprise at least 90 mol% of ethane.
• step f) said at least a portion of the ethane-enriched fraction can be recycled at a flow rate of between 5% and 20% of the ethane flow rate contained in said natural gas.
• the method according to the invention can operate under the following conditions:
• the fractionation column can operate at a pressure of between 40 bars and 60 bars, in step a), the natural gas may be cooled to a temperature of between 0 ° C. and -60 ° C., and
• the gaseous fraction in step c), can be cooled to a temperature of between -45 ° C. and -70 ° C.
• the liquid fraction in step e), can be separated in a deethanization column, said ethane-enriched fraction being obtained at the top of the deethanization column, the fraction enriched in heavier compounds than ethane. being obtained at the bottom of the deethanization column.
• the fraction enriched in ethane may be at least partially liquefied, a part of the liquid fraction enriched in ethane being introduced at the top of the deethanization column as reflux, another portion of the liquid fraction enriched in ethane being recycled. according to step f).
• the deethanization column may operate at a pressure of between 20 and 35 bar, and said fraction enriched in ethane may be at least partially liquefied by cooling to a temperature of between -5 ° C. and 10 ° C.
• the liquid fraction in step e), can be separated in a demethanizer column so as to obtain a gas stream enriched in methane and a liquid stream enriched in compounds heavier than methane, and then it is possible to separate the liquid flow in a deethanization column, said fraction enriched in ethane being obtained at the top of the deethanization column, the fraction enriched in heavier compounds than ethane being obtained at the bottom of the deethanization column.
• the fraction enriched in ethane may be at least partially liquefied, a part of the liquid fraction enriched in ethane being introduced at the top of the deethanization column as reflux, another portion of the liquid fraction enriched in ethane being recycled.
• a portion of the liquid phase obtained in step c) can be introduced at the top of the demethanizer column as reflux.
• the demethanization column can operating at a pressure of between 25 and 40 bar
• the deethanization column can operate at a pressure of between 20 and 35 bar
• said fraction enriched in ethane can be at least partially liquefied by cooling to a temperature between -5 ° C. and 10 0 C.
• FIG. 1 schematizes a liquefaction process with fractionation
• the natural gas arriving through line 1 may have been previously purified impurities such as water, hydrogen sulphide, carbon dioxide and mercury.
• the natural gas is introduced into the heat exchanger E1 to be cooled to partial liquefaction.
• the natural gas can be cooled to a temperature between 0 ° C and -60 ° C.
• the refrigeration is carried out by means of the refrigeration closed circuit C1 which operates by compression and expansion of a fluid refrigerant.
• the partially liquefied flow from E1 is introduced into fractionation zone F.
• the present invention proposes different embodiments of zone F, described with reference to FIGS. 2 to 5.
• the references of FIGS. 2 to 5 are identical to those of FIG. Figure 1 denote the same elements.
• Natural gas liquids are discharged as one or more NGL streams.
• the methane obtained in zone F is sub-cooled in exchanger E2 until complete liquefaction.
• the refrigeration is carried out by means of the refrigeration closed circuit C2 which operates by compression and expansion of a refrigerant fluid.
• the pressurized liquid natural gas is evacuated from E2 to be expanded in the expansion device V to atmospheric pressure to produce LNG liquid natural gas.
• the natural gas 1 is cooled and partially condensed in the exchanger E1 and then introduced into the fractionation column 2.
• the column 2 generally operates at a pressure of between 40 and 60 bar abs.
• the vapor obtained at the top of the column 2 is partially condensed by the condenser 3.
• the gaseous phase is separated from the liquid phase in the flask 4.
• the condenser 3 performs cooling at a very low temperature, generally between -45.degree. -70 0 C, using a refrigerant, for example used in the heat exchanger E2.
• the gas phase 5 is sent into the heat exchanger E2 to be liquefied.
• the liquid phase obtained at the bottom of the flask 4 is returned using the pump 6 through the conduit 7 at the top of the fractionation column 2 as reflux.
• the temperature at the bottom of the column is controlled by reboiler 12 so as to vaporize the light fractions present in liquid form at the bottom of column 2 and to limit their entrainment in line 8.
• the liquid phase obtained at the bottom of column 2 is discharged through line 8 to the deethanization column 14.
• Column 14 can operate between 20 and 35 bar abs. Column 14 makes it possible to separate a stream mainly comprising ethane discharged at the top and a stream comprising hydrocarbons heavier than ethane in the bottom.
• the ethane stream obtained at the top of the column 14 is partially or completely condensed by the cryogenic condenser 15 at a temperature between -5 ° C. and 10 ° C.
• the flow obtained at the outlet of the condenser 15 is sent into the flask. In the case where the flow of ethane is only partially condensed, an ethane vapor phase is discharged at the top of the flask 16.
• the liquid ethane obtained at the bottom of 16 is pumped by the pump 17 to be sent through line 18 to the top of column 14 as reflux.
• a fraction of the liquid ethane obtained at the bottom of the flask 16 can be sent to a storage zone via the duct 20.
• the bottom of the column 14 is kept at temperature by the reboiler 21 so as to eliminate the maximum amount of ethane from the C3 + cut discharged at the bottom of 14 through the conduit 22.
• the C3 cut can be separated, for example in a depropanizer column.
• the present invention proposes to recycle a portion of the stream rich in liquid ethane obtained at the bottom of the flask 16 to the fractionation column 2.
• the stream rich in ethane comprises at least 90% molar, preferably more than 98 mol%, of ethane. More specifically, with reference to FIG. 2, a portion of the liquid flow pumped by the pump 17 is introduced via the conduit 19 into the balloon 4. Alternatively, with reference to FIG. 3, a portion of the liquid flow pumped by the pump 17 is introduced into the reflux line 7 through the conduit 19. Thus the liquid phase obtained at the bottom of the flask 4 is assembled and mixed with the flow rich in ethane arriving via the conduit 19.
• the ethane recycle according to the invention makes it possible to significantly increase the recovery of propane at the bottom of the fractionation column 2.
• a stream rich in ethane having a molar flow rate of ethane is recycled. between 5% and 20 mol% of the molar flow rate of ethane contained in the gas to be treated arriving via line 1.
• the ethane recycle also enriches the natural gas discharged at the top of the column 2 ethane and thus enhance ethane and increase the calorific value of natural gas.
• the methods operate under the following conditions:
• the recycle rate that is to say the molar flow rate of ethane recycled via line 19 with respect to the molar flow rate of ethane contained in the gas arriving via line 1, is 5%.
• the recovery rate of C3 is defined as the ratio between the flow rate of C3 in line 22 relative to the flow rate of C3 in line 1.
• the invention makes it possible to improve the recovery of C3 and to move slightly away from critical conditions in the fractionation column and to improve the recovery rate of C3.
• the natural gas 1 is cooled and partially condensed in the exchanger E1 at a temperature between -60 ° C and 0 ° C, then introduced into the fractionation column 2.
• the column 2 can operate at a pressure between 40 bar and 60 bar.
• the vapor obtained at the top of the column 2 is partially condensed by the condenser 3.
• the gaseous phase is separated from the liquid phase in the flask 4.
• the condenser 3 performs cooling at a very low temperature, for example between -45 ° C. and -70 0 C, using a refrigerant, for example used in the heat exchanger E2.
• the gas phase 5 is sent into the heat exchanger E2 to be liquefied.
• the liquid phase obtained at the bottom of the flask 4 is returned using the pump 6 through the conduit 7 at the top of the fractionation column 2 as reflux.
• the liquid phase obtained at the bottom of column 2 is discharged through line 8 to a second fractionation column 9 to effect a second separation between methane and hydrocarbons heavier than methane, at a pressure lower than that of column 2
• the column 9 can operate at a pressure of between 25 bars and 40 bars.
• a portion of the liquid phase obtained at the bottom of the flask 4 is introduced at the top of the column 9 as reflux.
• the temperature at the bottom of the column 9 is controlled by the reboiler 12 so as to vaporize the light fractions present in liquid form at the bottom of the column 9 and to limit their entrainment in the pipe 13.
• the column 9 makes it possible to obtain, in head, a stream enriched in methane discharged through line 11 and, in bottom, a stream enriched in hydrocarbons heavier than methane.
• the liquid stream obtained at the bottom of the column 9 is introduced via the pipe 13 into the deethanization column 14.
• the column 14 operates at a lower pressure than in the column 9, for example at a pressure of between 20 bar and 35 bar .
• Column 14 makes it possible to separate a stream mainly comprising ethane discharged at the top and a stream comprising hydrocarbons heavier than ethane in the bottom.
• the ethane stream obtained at the top of the column 14 is partially or totally condensed by the cryogenic condenser 15 at a temperature between -5 ° C. and 10 ° C.
• the flow obtained at the outlet of the condenser 15 is sent to the reflux balloon 16.
• an ethane vapor phase is discharged at the top of the flask 16.
• the liquid ethane obtained at the bottom of 16 is pumped by the pump 17 to be sent via the pipe 18, at the top from column 14 as reflux.
• a fraction of the liquid ethane obtained at the bottom of the flask 16 can be sent to a storage zone via the conduit 20.
• the bottom of the column 14 is kept at temperature by the reboiler 21 so as to eliminate the maximum amount of ethane from the C3 + cut discharged at the bottom of 14 through line 22.
• the C3 + cut can be separated, for example in a depropanizer column.
• the present invention proposes to recycle a portion of the stream rich in liquid ethane obtained at the bottom of the flask 16 to the fractionation column 2. More specifically, with reference to FIG. 4, a portion of the liquid flow pumped by the pump 17 is introduced through the conduit 19 into the balloon 4. Alternatively, with reference to FIG. 5, a portion of the liquid flow pumped by the pump 17 is introduced into the reflux line 7 via the conduit 19. liquid phase obtained at the bottom of the flask 4 is assembled and mixed with the stream rich in ethane arriving via the conduit 19.
• the methods operate under the following conditions:
• Tapping flow 10 for reflux of the demethanizer 9 350 kmol / h
• the recycle rate that is to say the molar flow rate of ethane recycled via line 19 with respect to the molar flow rate of ethane contained in the gas arriving via line 1, is 10%.
• the recovery rate of C3 is defined as the ratio between the flow rate of C3 in line 22 relative to the flow rate of C3 in line 1.
• the invention makes it possible to improve the recovery of C3 and to move away from the critical conditions in the fractionation column especially when the recycle return is made in the reflux line.

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• 2007
  • 2007-10-26 FR FR0707602A patent/FR2923000B1/fr active Active
• 2008
  • 2008-10-17 EP EP08870226A patent/EP2205921A2/de not_active Withdrawn
  • 2008-10-17 RU RU2010121164/06A patent/RU2491487C2/ru active
  • 2008-10-17 WO PCT/FR2008/001461 patent/WO2009087307A2/fr not_active Ceased
  • 2008-10-17 US US12/739,048 patent/US20110265511A1/en not_active Abandoned
  • 2008-10-17 BR BRPI0818019 patent/BRPI0818019A2/pt active Search and Examination

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