US20100154469A1 - Process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles - Google Patents
Process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles Download PDFInfo
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- US20100154469A1 US20100154469A1 US12/317,150 US31715008A US2010154469A1 US 20100154469 A1 US20100154469 A1 US 20100154469A1 US 31715008 A US31715008 A US 31715008A US 2010154469 A1 US2010154469 A1 US 2010154469A1
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- hydrocarbon
- refrigerant
- liquefaction
- mixed refrigerant
- cooling
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- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000005057 refrigeration Methods 0.000 title claims abstract description 28
- 229930195733 hydrocarbon Natural products 0.000 title claims abstract description 20
- 150000002430 hydrocarbons Chemical class 0.000 title claims abstract description 20
- 239000004215 Carbon black (E152) Substances 0.000 title claims abstract description 17
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims abstract description 86
- 239000003507 refrigerant Substances 0.000 claims abstract description 68
- 238000001816 cooling Methods 0.000 claims abstract description 33
- 239000003345 natural gas Substances 0.000 claims abstract description 33
- 239000007789 gas Substances 0.000 claims abstract description 23
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 18
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 16
- NNPPMTNAJDCUHE-UHFFFAOYSA-N isobutane Chemical compound CC(C)C NNPPMTNAJDCUHE-UHFFFAOYSA-N 0.000 claims description 14
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 13
- 239000001294 propane Substances 0.000 claims description 9
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims description 5
- 239000005977 Ethylene Substances 0.000 claims description 5
- 239000000203 mixture Substances 0.000 abstract description 10
- 239000003949 liquefied natural gas Substances 0.000 description 25
- 238000005194 fractionation Methods 0.000 description 10
- 238000004088 simulation Methods 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 6
- 239000003570 air Substances 0.000 description 6
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 229910002092 carbon dioxide Inorganic materials 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 230000018044 dehydration Effects 0.000 description 3
- 238000006297 dehydration reaction Methods 0.000 description 3
- 238000009835 boiling Methods 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- QWTDNUCVQCZILF-UHFFFAOYSA-N iso-pentane Natural products CCC(C)C QWTDNUCVQCZILF-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 230000003278 mimic effect Effects 0.000 description 2
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000011144 upstream manufacturing Methods 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- 241000183024 Populus tremula Species 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 239000012080 ambient air Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
Images
Classifications
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- 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
- F25J1/003—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
- F25J1/0055—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 originating from an incorporated cascade
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- 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
- F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
- F25J1/008—Hydrocarbons
- F25J1/0085—Ethane; 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
- 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
- F25J1/0217—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 at least a three level refrigeration cascade with at least one MCR cycle
- F25J1/0218—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 at least a three level refrigeration cascade with at least one MCR cycle with one or more SCR cycles, e.g. with a C3 pre-cooling cycle
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- 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
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/64—Separating heavy hydrocarbons, e.g. NGL, LPG, C4+ hydrocarbons or heavy condensates in general
Definitions
- the present invention relates generally to the liquefaction of natural gas and more particularly to a gas liquefaction process having improved efficiency including three refrigeration cycles, namely pre-cooling, liquefaction and subcooling.
- Known processes for liquefying gas e.g. natural gas include a variety of process or flowsheet configurations. Such configurations include refrigeration cycles for liquefaction using between one and three pure refrigerants, one and three mixed refrigerants, or a combination thereof.
- the process can contain all closed loop refrigeration cycles, a cascade of refrigeration cycles or open loop refrigeration cycles.
- the liquefied natural gas industry continuously seeks to improve the efficiency of liquefaction.
- the invention relates to a process for liquefying a hydrocarbon-rich stream such as natural gas by indirect heat exchange with refrigerants in a cascade refrigeration cycle comprising three closed loop refrigeration cycles, characterized in that the refrigerants are subcooled and subjected to expansion, and the resultant cooled gas is heated in indirect heat exchange with the hydrocarbon-rich stream within at least one heat exchanger in each of the three cycles, and each of the resultant vaporized refrigerants is compressed, wherein:
- the first cycle pre-cools the hydrocarbon-rich stream utilizing a pre-cooling mixed refrigerant
- the second cycle liquefies the hydrocarbon-rich stream utilizing a liquefying pure refrigerant
- the third cycle subcools the hydrocarbon-rich stream utilizing a subcooling mixed refrigerant.
- FIG. 1 is a schematic diagram of the liquefaction process of one embodiment of the invention.
- Liquefied natural gas is natural gas that has been processed to remove impurities and heavy hydrocarbons and then condensed into a liquid at almost atmospheric pressure by cooling to approximately ⁇ 260° F. ( ⁇ 163° C.).
- the cooling curve is a plot of enthalpy versus temperature.
- pre-cooling As the natural gas is liquefied, there are three distinct sections within the cooling curve: pre-cooling, liquefaction, and subcooling.
- the refrigerants for use in the liquefaction process are selected based on a close match of the enthalpy-temperature relationships between the refrigerants and the particular gas to be liquefied. The closer the cooling curve and refrigeration curves, theoretically the more thermodynamically efficient the liquefaction process.
- the liquefaction process described in the first embodiment of the invention includes three stages of refrigeration utilizing: (a) a first mixed refrigerant for pre-cooling, (b) a pure refrigerant for liquefaction, and (c) a second mixed refrigerant for subcooling.
- the three stages or cycles mimic the cooling curve of the natural gas to be liquefied thus reducing the duty or power required as compared with traditional liquefaction processes and thereby increasing efficiency.
- Each refrigerant loop can be optimized with respect to energy consumption, operation, and equipment availability.
- the liquefaction process 100 in the first exemplary embodiment is illustrated in FIG. 1 .
- a natural gas stream 2 is fed to an acid gas removal unit 4 where the gas is first treated to remove carbon dioxide or other acid gases by any known means.
- the acid gas is removed at gas removal port 6 .
- the natural gas stream is then pre-cooled by a first mixed refrigerant (MR 1 ) utilizing first closed loop refrigeration cycle 8 at heat exchanger 10 .
- MR 1 mixed refrigerant
- the lower natural gas temperature enables better separation of water in dehydration column 12 where water is removed from water removal port 14 .
- the pre-cool cycle 8 optimizes the temperature to slightly above the hydrate formation temperature.
- the natural gas stream is then further cooled at heat exchanger 16 utilizing the first closed loop mixed refrigerant MR 1 to create an optimum temperature for the separation and removal of heavy hydrocarbons in fractionation column 18 .
- the fractionation column includes a condenser which utilizes the pure refrigerant to meet the cooling requirement.
- the gas can be pre-cooled to a temperature of about 24° F. ( ⁇ 5° C.) entering the fractionation column and about ⁇ 26° F. ( ⁇ 32° C.) exiting the fractionation column.
- the heavy hydrocarbons are removed by way of heavy hydrocarbon removal port 20 .
- the second closed loop refrigerant is a pure refrigerant (PR) and is utilized for further cooling within the fractionation column.
- the natural gas is then cross exchanged with pure refrigerant PR utilizing a second closed loop refrigeration cycle 22 for further temperature reduction at heat exchanger 24 .
- the natural gas stream can be cooled by the pure refrigerant to approximately ⁇ 105° F. ( ⁇ 76° C.), for example, prior to entering the final LNG heat exchanger 28 .
- the natural gas stream liquefies within this low pressure pure refrigerant cycle.
- the final, subcooling temperature reduction of the natural gas occurs in LNG heat exchanger 28 by heat exchange between the natural gas and a second mixed refrigerant (MR 2 ), utilizing third closed loop refrigeration cycle 26 .
- the second mixed refrigerant MR 2 is utilized in a first pass through the LNG exchanger 28 , and the LNG pressure is dropped for further temperature reduction followed by additional passes through the LNG exchanger 28 .
- the LNG exchanger 28 can subcool the LNG to storage temperatures of approximately ⁇ 257° F. ( ⁇ 161° C.), for example.
- the natural gas pressure is reduced to a suitable storage pressure through the use of a Joule-Thomson valve 30 , and sent to LNG storage 32 .
- the three closed loop refrigeration cycles 8 , 22 and 26 are utilized in a cascade type process wherein the second loop pure refrigerant PR cools the first loop mixed refrigerant MR 1 . Similarly, the third loop mixed refrigerant MR 2 cools the second loop refrigerant PR.
- Known process components of refrigeration cycles namely compression, cooling and pressure drop, are utilized in each closed loop refrigeration cycle to liquefy the refrigerant and prepare for heat exchange with the natural gas.
- Air coolers can optionally be used for interstage cooling of the refrigerant within the compression stages. Cooling water can optionally be utilized if available; this would advantageously further reduce energy usage if the outlet temperature were lower than the ambient air temperature.
- the liquefaction process illustrated in FIG. 1 was simulated as an example of the invention using HYSYS 2004.1 process simulation software (available from Aspen Technology Inc., Burlington, Mass.) to determine the overall duty requirement of the process of the simulated example.
- the acid gas removal, dehydration, and fractionation components of the liquefaction process were all simulated to ensure accurate values were used in calculating the overall duty required by the simulated process.
- Note, the rundown and the boil-off gas sections of the liquefaction plant were not simulated as these sections do not directly relate to the liquefaction process.
- feed gas composition and operating conditions assumed in the simulation are given in Table 1.
- the feed gas composition used in the simulation is natural gas, other hydrocarbon-rich gas compositions could be liquefied by the present exemplary process as well.
- Table 2 summarizes the final LNG composition and operating conditions as a result of the simulated liquefaction process as an example of the invention.
- the pre-cooling, cooling/liquefaction and subcooling temperatures in the simulation were those temperatures given as examples in the preceding paragraphs. Namely, the natural gas stream was assumed to be pre-cooled to approximately 24° F. ( ⁇ 5° C.) entering the fractionation column and approximately ⁇ 26° F. ( ⁇ 32° C.) exiting the fractionation column; the natural gas stream was assumed to be cooled by pure refrigerant to approximately ⁇ 105° F. ( ⁇ 76° C.) prior to entering the LNG heat exchanger 28 ; and the liquefied natural gas was assumed to be subcooled by the LNG exchanger 28 to approximately ⁇ 257° F. ( ⁇ 161° C.).
- the first mixed refrigerant (MR 1 ) is utilized in the pre-cool cycle of the liquefaction process.
- MR 1 is made-up of ethane, methane, and propane in a ratio that allows for optimizing thermodynamic properties, i.e., optimizing the match between the MR 1 and the pre-cooling portion of the gas cooling curve.
- MR 1 preferably contains ethane between about 10% and about 20%, propane between about 60% and about 70%, and i-butane between about 15% and about 25%.
- MR 1 is preferably about 16% ethane, about 64% propane and about 20% i-butane.
- MR 1 is compressed by compressor 42 to a high pressure. For the purposes of the simulation, it was assumed that MR 1 is compressed to approximately 240 psia, although this pressure can vary. MR 1 is then cooled by either chilled water or air (indicated in FIG. 1 by compressor/air cooler combinations 34 / 36 and 40 / 38 ). A discharge temperature of approximately 100° F. (38° C.) was assumed in order to ensure refrigeration requirements were met. MR 1 is then expanded over three pressure drops (the first indicated in FIG. 1 by expansion valves 44 and 46 and heat exchanger 48 ; the second indicated by expansion valves 54 and 56 and heat exchanger 50 ; and the third indicated by expansion valves 57 and heat exchanger 52 ).
- the first pressure drop is used to pre-cool the natural gas stream upstream of dehydration 12
- the second pressure drop is used to perform the first cooling of the pure refrigerant used in the liquefaction refrigeration cycle.
- the second pressure drop cools the natural gas feed upstream of the fractionation column 18 as well as further cools the pure refrigerant.
- the final pressure drop of MR 1 is used to liquefy the pure refrigerant.
- the heat exchangers used within each of the closed loop refrigeration cycles of the liquefaction process in the simulation (designated by numerals 48 , 50 , 52 , 92 , and 70 in FIG. 1 ) were assumed to be core-in-kettle type heat exchangers.
- a plate-and-fin type heat exchanger was assumed for the direct exchange between the first mixed refrigerant and the natural gas stream at heat exchanger 16 .
- MR 1 is compressed and begins the closed-loop cycle 8 again.
- the liquefaction cycle 22 of the liquefaction process is also a closed loop and utilizes a pure (i.e., single component) refrigerant (PR).
- PR refrigerant
- Any refrigerant can be used within the process as long as the thermodynamic properties match the cooling curve of the natural gas in the liquefaction portion of the curve, and the boiling point of the refrigerant is lower than the lowest boiling point of MR 1 .
- 100% ethylene was used as the PR.
- the PR is compressed to high pressure by compressor 74 and is then cooled by either chilling water or air (indicated by compressor/cooler combination 76 / 78 ). A 100° F. (38° C.) discharge temperature was assumed.
- the cold available from the MR 1 cycle is utilized to cool and liquefy the PR in three stages, in heat exchangers 48 , 50 and 52 .
- PR is then expanded over three pressure drops using expansion valves 58 and 60 in the first pressure drop, expansion valves 62 and 64 in the second pressure drop and expansion valves 66 and 68 in the third pressure drop.
- the pressure of PR is reduced prior to fractionation column 18 and in order to liquefy the natural gas feed stream prior to the natural gas entering the LNG exchanger 28 .
- MR 2 is cooled and condensed.
- the PR is then compressed by compressor 72 and the cycle 22 repeats.
- a plate-and-fin type heat exchanger was assumed for the direct exchange between the pure refrigerant and the natural gas stream at heat exchanger 24 .
- the final subcooling refrigeration cycle 26 is also a closed loop process.
- the subcooling cycle utilizes a second mixed refrigerant (MR 2 ) containing components of the natural gas stream, namely nitrogen, methane, and propane, in a ratio that allows for optimizing the match between MR 2 and the subcooling portion of the gas cooling curve.
- MR 2 preferably contains nitrogen between about 30% and about 40%, methane between about 30% and about 40%, and ethane between about 30% and about 40%.
- MR 2 is preferably about 33% nitrogen, about 33% methane and about 34% ethane.
- MR 2 is compressed to a high pressure by compressor 84 and is then cooled by either chilled water or the air (indicated by compressor/cooler combinations in 84 / 86 and 88 / 90 ).
- air was used with a discharge temperature of approximately 100° F. (38° C.).
- MR 2 is then condensed to a vapor fraction of approximately 0.5 by cross exchanging heat between MR 2 and PR at heat exchanger 92 .
- the vapor and liquid streams are separated by separator 80 and introduced separately into LNG heat exchanger 28 .
- a cold box type heat exchanger was assumed for use as LNG exchanger 28 .
- the use of other LNG exchanger e.g. a main cryogenic heat exchanger could also be used in the liquefaction process.
- Joule-Tompson valves 94 can be used to further reduce the temperature of the MR 2 streams (which recombine following the valves) within the LNG exchanger thereby subcooling the LNG. MR 2 is then recycled to the beginning of the cycle 26 .
- the process of the invention advantageously distributes the duty among all three refrigerants and produces a total duty per ton of LNG produced.
- Table 3 contains the values of the required duties from each refrigeration cycle and total from the pre-cooling/liquefaction/subcooling (MR 1 /PR/MR 2 ) liquefaction process.
- the unique refrigerant sequence allows adjustments to the cooling curve for optimization of the process.
- the cooling curve requirements vary depending on natural gas composition. Utilizing the first mixed refrigerant in the first stage, it is possible to vary the percentages of components of the first mixed refrigerant to mimic this portion of the cooling curve. In the second stage, it has been found that pure ethylene refrigerant is appropriate to match the cooling curve.
- the liquefaction process requires lower duty and offers higher efficiency than traditional liquefaction processes. The process requires 51 MW/MMTPA (megawatts/million metric tons per annum).
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Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
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US12/317,150 US20100154469A1 (en) | 2008-12-19 | 2008-12-19 | Process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles |
AU2009336080A AU2009336080A1 (en) | 2008-12-19 | 2009-11-02 | Improved process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles |
PCT/US2009/062957 WO2010080198A1 (fr) | 2008-12-19 | 2009-11-02 | Procédé et système perfectionnés pour la liquéfaction d'un courant de gaz riche en hydrocarbures à l'aide de trois cycles de réfrigération |
Applications Claiming Priority (1)
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US12/317,150 US20100154469A1 (en) | 2008-12-19 | 2008-12-19 | Process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles |
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US20100154469A1 true US20100154469A1 (en) | 2010-06-24 |
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US12/317,150 Abandoned US20100154469A1 (en) | 2008-12-19 | 2008-12-19 | Process and system for liquefaction of hydrocarbon-rich gas stream utilizing three refrigeration cycles |
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US (1) | US20100154469A1 (fr) |
AU (1) | AU2009336080A1 (fr) |
WO (1) | WO2010080198A1 (fr) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130145794A1 (en) * | 2010-03-05 | 2013-06-13 | Chad C. Rasmussen | "flexible liquefied natural gas plant" |
WO2014078092A1 (fr) * | 2012-11-16 | 2014-05-22 | Exxonmobil Upstream Research Company | Liquéfaction de gaz naturel |
AU2013203120B2 (en) * | 2012-09-18 | 2014-09-04 | Woodside Energy Technologies Pty Ltd | Production of ethane for startup of an lng train |
US10480851B2 (en) | 2013-03-15 | 2019-11-19 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
US11408673B2 (en) | 2013-03-15 | 2022-08-09 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
US11428463B2 (en) | 2013-03-15 | 2022-08-30 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
WO2023137492A1 (fr) * | 2022-01-14 | 2023-07-20 | Occidental Oil And Gas Corporation | Système et procédé de récupération de liquides hydrocarbonés à partir de flux de production gazeux ou dans des flux de production gazeux |
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US3763658A (en) * | 1970-01-12 | 1973-10-09 | Air Prod & Chem | Combined cascade and multicomponent refrigeration system and method |
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- 2009-11-02 AU AU2009336080A patent/AU2009336080A1/en not_active Abandoned
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US4755200A (en) * | 1987-02-27 | 1988-07-05 | Air Products And Chemicals, Inc. | Feed gas drier precooling in mixed refrigerant natural gas liquefaction processes |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20130145794A1 (en) * | 2010-03-05 | 2013-06-13 | Chad C. Rasmussen | "flexible liquefied natural gas plant" |
US20160040928A1 (en) * | 2010-03-05 | 2016-02-11 | Chad C. Rasmussen | Flexible Liquefied Natural Gas Plant |
US10378817B2 (en) * | 2010-03-05 | 2019-08-13 | Exxonmobil Upstream Research Company | Flexible liquefied natural gas plant |
AU2013203120B2 (en) * | 2012-09-18 | 2014-09-04 | Woodside Energy Technologies Pty Ltd | Production of ethane for startup of an lng train |
AP3543A (en) * | 2012-09-18 | 2016-01-13 | Woodside Energy Technologies Pty Ltd | Production of ethane for startup of an lng train |
WO2014078092A1 (fr) * | 2012-11-16 | 2014-05-22 | Exxonmobil Upstream Research Company | Liquéfaction de gaz naturel |
US10480851B2 (en) | 2013-03-15 | 2019-11-19 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
US11408673B2 (en) | 2013-03-15 | 2022-08-09 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
US11428463B2 (en) | 2013-03-15 | 2022-08-30 | Chart Energy & Chemicals, Inc. | Mixed refrigerant system and method |
WO2023137492A1 (fr) * | 2022-01-14 | 2023-07-20 | Occidental Oil And Gas Corporation | Système et procédé de récupération de liquides hydrocarbonés à partir de flux de production gazeux ou dans des flux de production gazeux |
Also Published As
Publication number | Publication date |
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WO2010080198A1 (fr) | 2010-07-15 |
AU2009336080A1 (en) | 2010-07-15 |
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