US3702063A - Refrigeration cycle for the aliquefaction of natural gas - Google Patents
Refrigeration cycle for the aliquefaction of natural gas Download PDFInfo
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- US3702063A US3702063A US873964A US3702063DA US3702063A US 3702063 A US3702063 A US 3702063A US 873964 A US873964 A US 873964A US 3702063D A US3702063D A US 3702063DA US 3702063 A US3702063 A US 3702063A
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- intercooler
- cycle
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- natural gas
- pressure
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 98
- 239000003345 natural gas Substances 0.000 title claims abstract description 44
- 238000005057 refrigeration Methods 0.000 title claims abstract description 34
- 239000012530 fluid Substances 0.000 claims abstract description 46
- 229930195733 hydrocarbon Natural products 0.000 claims abstract description 27
- 150000002430 hydrocarbons Chemical class 0.000 claims abstract description 26
- 238000009833 condensation Methods 0.000 claims abstract description 13
- 230000005494 condensation Effects 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims description 43
- 239000007789 gas Substances 0.000 claims description 29
- 239000007788 liquid Substances 0.000 claims description 27
- 230000006835 compression Effects 0.000 claims description 18
- 238000007906 compression Methods 0.000 claims description 18
- 239000000203 mixture Substances 0.000 claims description 17
- 238000004891 communication Methods 0.000 claims description 13
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000007791 liquid phase Substances 0.000 claims description 11
- 238000001816 cooling Methods 0.000 claims description 10
- 239000012808 vapor phase Substances 0.000 claims description 10
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 claims description 7
- 230000003247 decreasing effect Effects 0.000 claims description 5
- 238000005191 phase separation Methods 0.000 claims description 4
- 239000002826 coolant Substances 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims description 2
- 230000003134 recirculating effect Effects 0.000 claims description 2
- 238000009835 boiling Methods 0.000 description 7
- 230000008016 vaporization Effects 0.000 description 6
- 239000007792 gaseous phase Substances 0.000 description 5
- 238000009834 vaporization Methods 0.000 description 5
- 239000001294 propane Substances 0.000 description 4
- 239000000498 cooling water Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 241000252095 Congridae Species 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- IJDNQMDRQITEOD-UHFFFAOYSA-N n-butane Chemical compound CCCC IJDNQMDRQITEOD-UHFFFAOYSA-N 0.000 description 1
- OFBQJSOFQDEBGM-UHFFFAOYSA-N n-pentane Natural products CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 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
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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
- F25J1/003—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
- F25J1/0032—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
- F25J1/004—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by flash gas recovery
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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
- F25J1/003—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
- F25J1/0032—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration"
- F25J1/0045—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 the feed stream itself or separated fractions from it, i.e. "internal refrigeration" by vaporising a liquid return stream
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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
- F25J1/003—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
- F25J1/02—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
- F25J1/0201—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 only internal refrigeration means, i.e. without external refrigeration
- F25J1/0202—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 only internal refrigeration means, i.e. without external refrigeration in a quasi-closed internal refrigeration loop
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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
- F25J1/0211—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
- F25J1/0212—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 single flow MCR 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
- F25J2220/00—Processes or apparatus involving steps for the removal of impurities
- F25J2220/60—Separating impurities from natural gas, e.g. mercury, cyclic hydrocarbons
- F25J2220/62—Separating low boiling components, e.g. He, H2, N2, Air
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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
- 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
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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
- F25J2230/00—Processes or apparatus involving steps for increasing the pressure of gaseous process streams
- F25J2230/30—Compression of the feed stream
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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
- F25J2245/00—Processes or apparatus involving steps for recycling of process streams
- F25J2245/90—Processes or apparatus involving steps for recycling of process streams the recycled stream being boil-off gas from storage
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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
- F25J2290/00—Other details not covered by groups F25J2200/00 - F25J2280/00
- F25J2290/62—Details of storing a fluid in a tank
Definitions
- ABSTRACT In the liquefaction of natural gas wherein the refrigeration cycle fluid contains natural gas components, and such components are subjected to fractional condensation to obtain different temperature levels of refrigeration, the system is improved by'adjusting the C -C content of cycle fluid and the pressure of at least one intermediate pressure stage of the circulation pressure in such a manner that condensate is formed in the corresponding intercooler of said pressure stage. This condensate is then separated and subjected to heat exchange to utilize its refrigeration values and recirculated to the circulation compressor via an expansion valve. In this way, a substantial concentration of heavy hydrocarbons can be utilized to increase the refrigeration capacity of the refrigeration cycle, but said hydrocarbons do not deleteriously affect the lower temperature levels of refrigeration.
- the function of the refrigeration cycle is to produce the refrigeration required for liquefying natural gas [depending on climatic conditions having an ambient]. Another object is to provide apparatus for conducting such a process.
- a refrigeration cycle fluid is advantageously employed which is composed of components also having differing boiling points, as disclosed, for example, by A. P. Kleemenko (Comptes rendus du'Congres du Froid de Copenhague 1959, pp. 34-39).
- the cycle fluid is then partially condensed in multiple stages, each liquid fraction being separated from the gaseous phase, expanded, vaporized, heated and recycled to the compressor.
- the components having low boiling points such as methane and nitrogen, yield the refrigeration required at the lowest temperature level whereas the fraction containing ethane and propane yields refrigeration values at an intermediate temperature level.
- the refrigeration required for the precooling step i.e. for cooling to a temperature corresponding approximately to the boiling point of ammonia at atmospheric pressure (33C.), is produced by the vaporization of a mixture of higher hydrocarbons, such as propane, butane, and higher-boiling compounds.
- a principal object of this invention is to provide an improved process for the liquefaction of natural gas so that the refrigerating capacity of the cycle fluid is increased without deleteriously affecting the temperature level of the lower temperature refrigerating stages.
- the resultant warmed gas is recycled to the inlet side of the circulation compressor.
- the condensate is expanded (pressure-reduced) exclusively of any condensate of the vapor phase separated therefrom in the preceding step; the resultant separated vapor is then recompressed downstream of the intermediate compression stage, and then subjected to multiple stages of condensation, phase separation, and expansion of resultant condensates to produce the required multiple stages of decreasing temperature necessary for liquefying the natural gas.
- the molecular weight of the condensate after the cooling step followingthe intermediate compression stage is about 40 to 70, preferably 50 to 60, and that of the resultant vapor about 20 to 40, preferably 20 to 30.
- the advantage of the abovedescribed system resides in that the refrigeration capacity of the cycle is increased, due to the presence of larger amounts of C -C hydrocarbons, and that simultaneously, by the partial condensation after the intermediate cooling in the intercooler, the partial pressure of these hydrocarbons in the refrigeration medium passing into the lowest temperature stages is maintained at such a low level that there is no undesired increase of th vaporization temperature in such stages.
- FIG. 1 is a schematic diagram of a preferred embodiment of this invention wherein the natural gas is intermixed with cycle fluid.
- FIG. 2 is a schematic diagram of another preferred embodiment wherein the natural gas is liquefied independent of any intermixing with cycle fluid.
- the pressure of the intermediate compression stage and the content of C -C hydrocarbons in the cycle fluid are adjusted.
- the pressure of the intermediate compression stage is advantageous for the pressure of the intermediate compression stage to be the same or substantially the same as the natural gas pressure, generally about 45 to 35, preferably 10 to 25 atrnospheres absolute.
- the cycle gas must have about the following composition:
- the invention is applied in a particularly suitable manner to a process wherein the required refrigeration is produced by a single cycle, and the cycle fluid is subjected to a multi-stage partial condensation, where, in each instance, the condensate is separated, expanded to the inlet pressure of the circulation compressor, vaporized and'warmed in heat exchange with cycle fluid and natural gas, and recycled to the circulation compressor.
- a high liquefaction efficiency is obtained witha low expenditure in apparatus, and, furthermore, the process can be easily adapted to various natural gas compositions and operating conditions.
- the apparatus for conducting the process according to the invention comprises as the essential novelty, a separator connected after at least one intercooler of the circulation compressor, which separator is in communication in the gas phase via a conduit, with the subsequent compression stage and, in the liquid phase, via an expansion valve, and the refrigerating cycle path of a heat exchanger, with the inlet side of the circulation compressor, and associated conduit.
- FIG. 1 shows a process with arropen cycle, i.e. wherein the natural gas to be liquefied is compressed and brought to a low temperature together with the cycle gas.
- the cycle fluid has approximately the following composition:
- 20,000 Nm lh of the cycle gas is fed at about 6 atmospheres absolute through conduit 1 to the inletside of the first compressor stage 2, compressed at that point to about 20 atmospheres absolute, and brought to the cooling water temperature in the intercooler 3.
- 1,000 Nmlh of the cycle fluid are liquefied during this step, separated from the gaseous phase in the separator 4, cooled to about 280K. in, the heat exchanger 5, and expanded through valve 6 into the conduit 1 whereupon it is then reintroduced to the first stage of the compressor.
- the gas leaving the separator 4, together with 6,000 Nm /h of natural gas (freed of C0,, H 8, and B 0), is compressed in the second compressor stage 8 to about 35 atmospheres absolute.
- the final cooler 9 there is again obtained about 1,000 Nm /h of liquid, the
- a small portion of the subcooled liquid from separator 10 is expanded, at the. cold" end of the heat exchanger 5, via valve 13 into the conduit 27 leading to the gasometer.
- the amount and composition of this stream are chosen so that the C,- and higher hydrocarbons entering the plant together with the natural gas again are discharged from the plant by this path.
- the gas from the separator 10 is cooled, in heat exchanger 5, to about 280K. and is partially coridensed during this step.
- the liquid about 4,200 Nm lh, is separated from the vapor. Both fractions are cooled in heat exchanger 15 to about 245K.
- the subcooled liquid is expanded, admixed 'to the returning cycle gas, and vaporized in heat exchanger l5.
- the gas is once again partially condensed and separated, in separator 16, into a liquid and a gaseous phase.
- the amount of the thus-formed liquid is about 6,000 Nm /h.
- the .vapor separated in separator 20 is cooled, liquefied, and subcooled in heat exchangers 21 and 23.
- the liquid passes at a temperature of about 115K. into the storage tank 25 by way of expansion valve 24.
- the temperature at the cold end of the heat exchanger 23 is obtained by expansion and vaporization of a portion of the liquid leaving the heat exchanger 23; this liquidis expanded via valve 26 into the conduit 27 leading to the gasometer, and is discharged from the plant via the heat exchangers 23, 21, 19, 17, 15, and 5.
- the gas vaporized in the storage tank 25 by the effect of heat is withdrawn via conduit 28 and conveyed, through the cold gas blower 29, and via conduit 27 to the gasometer.
- the pressure and temperature conditions ambient in the individual separators are set forth (P in atmospheres absolute, Tin K.), as well as the total amount fed to each separator (F in Nm lh), the amount of liquid separated therein (1. in Nm lh), and also the approximate molecular weight of the it can be seen from the above table that in the separator 4, propane (molecular weight 44) and the higher hydrocarbons are obtained in the liquid phase.
- the liquid in separator consists essentially of propane; in separators l4 and 16, the proportion of ethane (molecular weight 30) increases in the liquid.
- separators 18 and 20 a mixture of ethane and methane (molecular weight 16) is separated.
- the gas leaving the separator 20 is mostly methane.
- the molecular weight of the gaseous phase decreases from separator to separator.
- the cycle fluid has the following compositions:
- the improvement comprising employing as said circulation compressor, a multi-stage compressor, adjusting the concentration of C,,- to C,- hydrocarbons in the cycle fluid, and the pressure of at least one intermediate stage of the circulation compressor, with respect to each other so that a portion of the effluent from said intermediate stage is condensible by heat exchange with cooling water; cooling said effluent from said intermediate stage in an intercooler between two successive pressure stages to form a liquid phase condensate containing a substantial concentration of heavy hydrocarbons and a vapor phase; separating said condensate from said vapor phase; pressure-reducing said condensate exclusively of any condensate of said vapor phase separated therefrom; vaporizing and heating resultant pressure-reduced condensate in heat exchange with the natural gas to be liquefied and the cycle fluid; recycling resultant heated vaporized condensate to the inlet side of the circulation compressor, recompressing said vapor separated from said condensate containing a substantial concentration of heavy hydrocarbons, and subject
- said natural gas being intermixed with cycle fluid.
- Apparatusifor the liquefaction of natural gas comprising:
- a condensate separator (4) having inlet means and gas outlet means and liquid outlet means;
- At least one intercooler (3) having inlet and outlet means; said inlet means of said condensate separator being in communication with said outlet means of said intercooler;
- a circulation compressor having at least two serially connected compression stages, said inlet means of said intercooler being in communication with the outlet of an intermediate compression stage, said gas outlet means of said condensate separator being disposed before, and in communication with the inlet side of the last serially connected compression stage ⁇ (8);
- an expansion valve (6) being in communication with the liquid outlet means of said condensate separator and separate unbranched conduit means for conducting liquid from said liquid outlet means exclusively to said expansion valve;
- heat exchange means includingseparate flow paths for expanded condensate, natural gas to be liquefied, and cycle liquid; and conduit means for effecting said communications and also for recirculating resultant heated expanded condensate from said heatexchange' means and said expansion valve to the inlet of said circulation compressor, and
- liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about -70 and said vapor phase separated therefrom having a molecular weight of about 20-40.
- liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about -60 and said vapor phase separated therefrom having a molecularlweight of about 20-30.
- a process as defined b claim 2 comprising the steps of passing said vapor separated from said condensate having a substantial concentration of heavy hydrocarbons to a final compression stage of said multi-stage compressor; cooling resultant compressed vapor to form a liquid phase and a vapor phase; passing the just-mentioned liquid phase 7 through a heat exchanger, and expanding a portion of resultant heat exchanged fluid and discharging the latter from said liquefaction cycle, said portion being of sufficient amount and of a composition to remove C and higher hydrocarbons from the natural gas intermixed with said cycle fluid.
Abstract
In the liquefaction of natural gas wherein the refrigeration cycle fluid contains natural gas components, and such components are subjected to fractional condensation to obtain different temperature levels of refrigeration, the system is improved by adjusting the C3-C6 content of cycle fluid and the pressure of at least one intermediate pressure stage of the circulation pressure in such a manner that condensate is formed in the corresponding intercooler of said pressure stage. This condensate is then separated and subjected to heat exchange to utilize its refrigeration values and recirculated to the circulation compressor via an expansion valve. In this way, a substantial concentration of heavy hydrocarbons can be utilized to increase the refrigeration capacity of the refrigeration cycle, but said hydrocarbons do not deleteriously affect the lower temperature levels of refrigeration.
Description
[451 Nov. 7, 1972 [54] REFRIGERATION CYCLE FOR THE ALIQUEFACTION OF NATURALGAS [72] Inventors: Volker Etzbach, Munich; Wolfgang Fiirg, Grunwald, both of Germany [73] Assignee: Linde Aktiengesellschaft, Hollriegelskreuth, Germany 22 Filed: Nov. 4, 1969 21] ,Appl. No.: 873,964
[30] Foreign Application Priority Date Nov. 4, 1968 Germany ..P 18 06 879.6
[52] US. Cl ..62/23, 62/40 [51] Int. Cl ..F25j 1/00, F2Sj 5/00, F25j 1/02 [58] Field of Search ..62/9, 11, 23, 24, 40
[56] References Cited UNITED STATES PATENTS 3,364,685 Il 1968 Perret ..62/40 3,274,787 9/ 1966 Grenier ..62/28 3,548,606 12/ l 970 Kuerston ..62/40 FOREIGN PATENTS OR APPLICATIONS 895,094 5/1962 Great Britain ..62/40 1,557,019 1/1969 France ..62/40 OTHER PUBLICATIONS Kleemenko, A. P.; Ope Flow Cascade Cycle in Progress in Refrigeration Science 8: Technology, Pergamon Press 1960 pp. 34- 39.
Primary Examiner-Norman Yudkoff Assistant Examiner-Arthur F. Purcell Attorney-I. William Millen [5 7] ABSTRACT In the liquefaction of natural gas wherein the refrigeration cycle fluid contains natural gas components, and such components are subjected to fractional condensation to obtain different temperature levels of refrigeration, the system is improved by'adjusting the C -C content of cycle fluid and the pressure of at least one intermediate pressure stage of the circulation pressure in such a manner that condensate is formed in the corresponding intercooler of said pressure stage. This condensate is then separated and subjected to heat exchange to utilize its refrigeration values and recirculated to the circulation compressor via an expansion valve. In this way, a substantial concentration of heavy hydrocarbons can be utilized to increase the refrigeration capacity of the refrigeration cycle, but said hydrocarbons do not deleteriously affect the lower temperature levels of refrigeration.
17 Claims, 2 Drawing Figures PATENTEUNUV 7 m2 SHEET 1 0F 2 27 INVENTORS WOLFGANG FORG PATENTEDNHY Hm Y 3,702,063
The function of the refrigeration cycle is to produce the refrigeration required for liquefying natural gas [depending on climatic conditions having an ambient Another object is to provide apparatus for conducting such a process.
Upon further study of the specification and appended claims, other objects and advantages of the invention will become apparent.
These objects are attained, according to this invention, by adjusting both the concentration of the C,C, hydrocarbons in the cycle fluid and the pressure of the intermediate stages of the circulation (cycle) compressor in'relation to each other so that a condensate is formed after the cooling step following the intermediate compression stage. This condensate is then separated, expanded,. vaporized, and then heated in heat exchange with both the natural gas to be liquefied temperature (generally about +40C.)].
Because the natural gas contains components having different liquefaction temperatures, a refrigeration cycle fluid is advantageously employed which is composed of components also having differing boiling points, as disclosed, for example, by A. P. Kleemenko (Comptes rendus du'Congres du Froid de Copenhague 1959, pp. 34-39).
The cycle fluid is then partially condensed in multiple stages, each liquid fraction being separated from the gaseous phase, expanded, vaporized, heated and recycled to the compressor. The components having low boiling points, such as methane and nitrogen, yield the refrigeration required at the lowest temperature level whereas the fraction containing ethane and propane yields refrigeration values at an intermediate temperature level. The refrigeration required for the precooling step, i.e. for cooling to a temperature corresponding approximately to the boiling point of ammonia at atmospheric pressure (33C.), is produced by the vaporization of a mixture of higher hydrocarbons, such as propane, butane, and higher-boiling compounds.
From the standpoint of refrigeration it is desirable that the higher hydrocarbons are present in the cycle fluid in large quantities. This is the case because they exhibit a higher latent heat of vaporization than the lower-boiling cycle fluid components, so that, with an increase in their concentration, the refrigerating capacity of the cycle, based on 1 Nm of circulated cycle gas, likewise increases. However, serious problems ordinarily result from the use of a high concentration of higher hydrocarbons. Specifically, during the subsequent partial condensation steps, an unacceptable amount of higher hydrocarbon remains in the gaseous phase, passes with the low-boiling cycle gas components into the final expansion stages, and in such final stages elevates the vaporization temperature above the desired refrigeration level and, in certain cases, gives rise to solid deposits in the refrigeration cycle, causing eventual damage or shut-down of the process.
SUMMARY OF THE INVENTION Bearing the above problems in mind, a principal object of this invention is to provide an improved process for the liquefaction of natural gas so that the refrigerating capacity of the cycle fluid is increased without deleteriously affecting the temperature level of the lower temperature refrigerating stages.
' Component and the cycle fluid. After the latter heat exchange step, the resultant warmed gas is recycled to the inlet side of the circulation compressor. It is important to note that the condensate is expanded (pressure-reduced) exclusively of any condensate of the vapor phase separated therefrom in the preceding step; the resultant separated vapor is then recompressed downstream of the intermediate compression stage, and then subjected to multiple stages of condensation, phase separation, and expansion of resultant condensates to produce the required multiple stages of decreasing temperature necessary for liquefying the natural gas.
In general, the molecular weight of the condensate after the cooling step followingthe intermediate compression stage is about 40 to 70, preferably 50 to 60, and that of the resultant vapor about 20 to 40, preferably 20 to 30.
The advantage of the abovedescribed system resides in that the refrigeration capacity of the cycle is increased, due to the presence of larger amounts of C -C hydrocarbons, and that simultaneously, by the partial condensation after the intermediate cooling in the intercooler, the partial pressure of these hydrocarbons in the refrigeration medium passing into the lowest temperature stages is maintained at such a low level that there is no undesired increase of th vaporization temperature in such stages. I
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic diagram of a preferred embodiment of this invention wherein the natural gas is intermixed with cycle fluid.
FIG. 2 is a schematic diagram of another preferred embodiment wherein the natural gas is liquefied independent of any intermixing with cycle fluid.
DETAILED DISCUSSION In order to obtain the desired molecular weight of condensate and vapor after the cooling step following the intermediate compression stage, the pressure of the intermediate compression stage and the content of C -C hydrocarbons in the cycle fluid are adjusted. When the natural gas to be liquefied is intermixed with cycle fluid, it is advantageous for the pressure of the intermediate compression stage to be the same or substantially the same as the natural gas pressure, generally about 45 to 35, preferably 10 to 25 atrnospheres absolute. Under such conditions the cycle gas must have about the following composition:
General by Volume N, -5 0.05-2 CH 30-50 35-40 Cgl. 20-50 20-40 CJI, 10-40 10-30 C H O-I 5 4-12 CJ-I 0-3 l-2 CJiu 0-2 l-2 Component 7 General Preferred by Volume by Volume CJI. or C,I-I, -40 35-45 ,CJ-l 10-20 10-15 For optimum economics, a chemical engineer can select the precise conditions of the process, depending on energy costs at the plant site, etc. It is also to be noted that theseminor components may exist in the cycle gas, such as helium, CO and H 8 and, if so, appropriate adjustments will again be made to optimize the process.
In any case, there is no question that a chemical 'engineer will be able to make the necessary adjustments of the pressure in the intermediate circulation compressor and the content of C C hydrocarbons in the cycle fluid to obtain a condensate after the cooling step following the intermediate compression step. For, this purpose, such cooling steps will generally be conducted so that the cycle fluid is cooled to about 10 to 35, preferably 20v to 30C., dependent on the cooling water temperature.
The inventionis applied in a particularly suitable manner to a process wherein the required refrigeration is produced by a single cycle, and the cycle fluid is subjected to a multi-stage partial condensation, where, in each instance, the condensate is separated, expanded to the inlet pressure of the circulation compressor, vaporized and'warmed in heat exchange with cycle fluid and natural gas, and recycled to the circulation compressor. By this process, a high liquefaction efficiency is obtained witha low expenditure in apparatus, and, furthermore, the process can be easily adapted to various natural gas compositions and operating conditions.
The apparatus for conducting the process according to the invention comprises as the essential novelty, a separator connected after at least one intercooler of the circulation compressor, which separator is in communication in the gas phase via a conduit, with the subsequent compression stage and, in the liquid phase, via an expansion valve, and the refrigerating cycle path of a heat exchanger, with the inlet side of the circulation compressor, and associated conduit.
DETAILED DESCRIPTION OF DRAWINGS Without further elaboration, it is believed that one skilled in the art can, using the preceding description,
' utilize the present invention to its fullest extent. The
following preferred specific embodiments are,'therefore, to be construed as merely illustrative, and not limitative of the remainderof the disclosure in any way whatsoever.
FIG. 1 shows a process with arropen cycle, i.e. wherein the natural gas to be liquefied is compressed and brought to a low temperature together with the cycle gas. The cycle fluid has approximately the following composition:
20,000 Nm lh of the cycle gas is fed at about 6 atmospheres absolute through conduit 1 to the inletside of the first compressor stage 2, compressed at that point to about 20 atmospheres absolute, and brought to the cooling water temperature in the intercooler 3. 1,000 Nmlh of the cycle fluid are liquefied during this step, separated from the gaseous phase in the separator 4, cooled to about 280K. in, the heat exchanger 5, and expanded through valve 6 into the conduit 1 whereupon it is then reintroduced to the first stage of the compressor. The gas leaving the separator 4, together with 6,000 Nm /h of natural gas (freed of C0,, H 8, and B 0), is compressed in the second compressor stage 8 to about 35 atmospheres absolute. In the final cooler 9, there is again obtained about 1,000 Nm /h of liquid, the
latter being collected in the separator 10 and subcooled in heat exchanger 5. The major portion of the subcooled liquid expanded by valve 11, into the conduit 1, is then vaporized and heated in heat exchanger 5. Before the resultant cycle gas is again returned to the first compressor stage, it passes throughtheliquid trap 12,
the latter protecting the compressor from liquid impacts, for example when the plant is placed on stream, or in case of operating errors.
A small portion of the subcooled liquid from separator 10 is expanded, at the. cold" end of the heat exchanger 5, via valve 13 into the conduit 27 leading to the gasometer. In this connection, the amount and composition of this stream are chosen so that the C,- and higher hydrocarbons entering the plant together with the natural gas again are discharged from the plant by this path.
The gas from the separator 10 is cooled, in heat exchanger 5, to about 280K. and is partially coridensed during this step. In the separator 14, the liquid, about 4,200 Nm lh, is separated from the vapor. Both fractions are cooled in heat exchanger 15 to about 245K. The subcooled liquid is expanded, admixed 'to the returning cycle gas, and vaporized in heat exchanger l5. The gas is once again partially condensed and separated, in separator 16, into a liquid and a gaseous phase. The amount of the thus-formed liquid is about 6,000 Nm /h.
Both phases are now cooled in heat exchanger 17 to about K. The subcooled liquid is expanded, in the manner described above, into the recycling cycle gas,
vaporized and warmed in heat exchangers 2l and 19, then mixed with the liquid from separator 16, which liquid was subcooled in heat exchanger 17, and recycled in the mannerdescribed above to the circulation compressor.
' The .vapor separated in separator 20 is cooled, liquefied, and subcooled in heat exchangers 21 and 23. The liquid passes at a temperature of about 115K. into the storage tank 25 by way of expansion valve 24. The temperature at the cold end of the heat exchanger 23 is obtained by expansion and vaporization of a portion of the liquid leaving the heat exchanger 23; this liquidis expanded via valve 26 into the conduit 27 leading to the gasometer, and is discharged from the plant via the heat exchangers 23, 21, 19, 17, 15, and 5. The gas vaporized in the storage tank 25 by the effect of heat is withdrawn via conduit 28 and conveyed, through the cold gas blower 29, and via conduit 27 to the gasometer.
in the following table, the pressure and temperature conditions ambient in the individual separators are set forth (P in atmospheres absolute, Tin K.), as well as the total amount fed to each separator (F in Nm lh), the amount of liquid separated therein (1. in Nm lh), and also the approximate molecular weight of the it can be seen from the above table that in the separator 4, propane (molecular weight 44) and the higher hydrocarbons are obtained in the liquid phase. The liquid in separator consists essentially of propane; in separators l4 and 16, the proportion of ethane (molecular weight 30) increases in the liquid. In separators 18 and 20, a mixture of ethane and methane (molecular weight 16) is separated. The gas leaving the separator 20 is mostly methane. In a similar manner, the molecular weight of the gaseous phase decreases from separator to separator.
Referring now to FIG. 2, there is disclosed another important embodiment of this invention wherein a closed cycle is employed, i.e. when natural gas and cycle medium are always conducted separately from each other. Identical structural components bear identical reference numerals. The cycle fluid has the following compositions:
1-5% N, 8-2096 CJ' m 2.045% ca, 24% c,i-i,, 35-50% car, ol n The essential difference as compared to FIG. 1 resides in that the natural gas is not fed via conduit 7 to the second compressor stage 8, but rather via conduit 40 to the heat exchanger 5 and then to the low-temperature plant disposed thereafter as in FIG. 1. This embodiment obviates the need for a device for the removal of the high boiling hydrocarbons introduced into the cycle by the natural gas, as would correspond to the valve 13 of FIG. 1.
From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention, to adapt it to various usages and conditions.
What is claimed is:
1. in a process for the liquefaction of natural gas, said process employing at least one refrigeration cycle, wherein the refrigeration cycle fluid contains natural gas components and is compressed, cooled, liquefied, expanded, vaporized and heated in heat exchange with cycle fluid and natural gas to be liquefied, and recycled to the circulation compressor, said process having multiple stages of decreasing temperature,
the improvement comprising employing as said circulation compressor, a multi-stage compressor, adjusting the concentration of C,,- to C,- hydrocarbons in the cycle fluid, and the pressure of at least one intermediate stage of the circulation compressor, with respect to each other so that a portion of the effluent from said intermediate stage is condensible by heat exchange with cooling water; cooling said effluent from said intermediate stage in an intercooler between two successive pressure stages to form a liquid phase condensate containing a substantial concentration of heavy hydrocarbons and a vapor phase; separating said condensate from said vapor phase; pressure-reducing said condensate exclusively of any condensate of said vapor phase separated therefrom; vaporizing and heating resultant pressure-reduced condensate in heat exchange with the natural gas to be liquefied and the cycle fluid; recycling resultant heated vaporized condensate to the inlet side of the circulation compressor, recompressing said vapor separated from said condensate containing a substantial concentration of heavy hydrocarbons, and subjecting resultant recompressed vapor to multiple stages of partial condensation, phase separation, and expansion of resultant condensates to produce said multiple stages of decreasing temperature.
2. A process as defined by claim 1, wherein the pressure of fluid leaving said intercooler is substantially the same as the pressure of the natural gas to be liquefied, said natural gas being intermixed into cycle fluid.
3. A process as defined by claim 1, wherein the required refrigeration is produced by a single cycle, and the cycle fluid is subjected to a multi-stage partial condensation, wherein, in each partial condensation, the condensate is separated, expanded to the inlet pressure of the circulation compressor, vaporized and warmed in heat exchange with cycle fluid and natural gas, and recycled to the circulation compressor.
4. A process as defined by claim 3, wherein the pressure of fluid leaving said intercooler is substantially the same as the pressure of the natural gas to be liquefied,
said natural gas being intermixed with cycle fluid.
5. Apparatusifor the liquefaction of natural gas, said apparatus comprising:
a condensate separator (4) having inlet means and gas outlet means and liquid outlet means;
at least one intercooler (3) having inlet and outlet means; said inlet means of said condensate separator being in communication with said outlet means of said intercooler;
a circulation compressor having at least two serially connected compression stages, said inlet means of said intercooler being in communication with the outlet of an intermediate compression stage, said gas outlet means of said condensate separator being disposed before, and in communication with the inlet side of the last serially connected compression stage \(8);
an expansion valve (6) being in communication with the liquid outlet means of said condensate separator and separate unbranched conduit means for conducting liquid from said liquid outlet means exclusively to said expansion valve;
heat exchange means includingseparate flow paths for expanded condensate, natural gas to be liquefied, and cycle liquid; and conduit means for effecting said communications and also for recirculating resultant heated expanded condensate from said heatexchange' means and said expansion valve to the inlet of said circulation compressor, and
means for effecting multiple stages of partial condensation, phase separation, and expansion of resultant condensates, said mean being in communication with the outlet side of the last serially connected compression stage (8).
6. A process as defined by claim 1 wherein fluid entering said intercooler is cooled to about l-30C. in said intercooler.
7. A process as defined by claim 6 wherein fluid entering said intercooler is cooled to about 20-30C, in said intercooler.
8. A process as defined by claim 2, said pressure being about 15-45 atmospheres absolute.
9. A process as defined by claim 8, thecycle gas entering the intercooler having the following composition in per cent by volume:
0-5 N,; 30-50 CH 20-50 C,H,; 10-40 C l-I 0-15 10. A process as defined by claim 2', said pressure being about 10-25 atmospheres absolute.
11. A process as defined by claim 10, the cycle gas entering the intercooler having the, following composition in per cent by volume:
0.05-2 N,; 35-40 C 2040 QB 10-30 C l-1,; 4-12 12. A process as defined by claim 1, said refrigeration cycle being a closed-cycle, the pressure entering the intercooler being 2-20 atmospheres absolute and the gas entering the intercooler having the following composition in per cent by volume:
0-10 N,; 10-40 CH 20-40 C,H, or C,H 0-20 C,H 10-20 C H 0-20 C 11 and 0-20 C H 13. A process as defined byclaim 1, said refrigera- 3:22asso'srssstflasffizamassassin the gas entering the intercooler having the following composition in per cent by volume:
2-6 N,; -40 CH4; -45 CJ-I, or C,l-l 0-3 C l-I 14. A process as defined by claim 1, said liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about -70 and said vapor phase separated therefrom having a molecular weight of about 20-40.
15. A process as defined by claim 1, said liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about -60 and said vapor phase separated therefrom having a molecularlweight of about 20-30.
16. A process as defined b claim 2 comprising the steps of passing said vapor separated from said condensate having a substantial concentration of heavy hydrocarbons to a final compression stage of said multi-stage compressor; cooling resultant compressed vapor to form a liquid phase and a vapor phase; passing the just-mentioned liquid phase 7 through a heat exchanger, and expanding a portion of resultant heat exchanged fluid and discharging the latter from said liquefaction cycle, said portion being of sufficient amount and of a composition to remove C and higher hydrocarbons from the natural gas intermixed with said cycle fluid.
17. A process as defined by claim 1, said condensate from said intercooler being employed as a cooling medium only in the higher temperature stages of said multiple stages of decreasing temperature.
Claims (16)
- 2. A process as defined by claim 1, wherein the pressure of fluid leaving said intercooler is substantially the same as the pressure of the natural gas to be liquefied, said natural gas being intermixed into cycle fluid.
- 3. A process as defined by claim 1, wherein the required refrigeration is produced by a single cycle, and the cycle fluid is subjected to a multi-stage partial condensation, wherein, in each partial condensation, the condensate is separated, expanded to the inlet pressure of the circulation compressor, vaporized and warmed in heat exchange with cycle fluid and natural gas, and recycled to the circulation compressor.
- 4. A process as defined by claim 3, wherein the pressure of fluid leaving said intercooler is substantially the same as the pressure of the natural gas to be liquefied, said natural gas being intermixed with cycle fluid.
- 5. Apparatus for the liquefaction of natural gas, said apparatus comprising: a condensate separator (4) having inlet means and gas outlet means and liquid outlet means; at least one intercooler (3) having inlet and outlet means; said inlet means of said condensate separator being in communication with said outlet means of said intercooler; a circulation compressor having at least two serially connected compression stages, said inlet means of said intercooler being in communication with the outlet of an intermediate compression stage, said gas outlet means of said condensate separator being disposed before, and in communication with the inlet side of the last serially connected compression stage (8); an expansion valve (6) being in communication with the liquid outlet means of said condensate separator and separate unbranched conduit means for conducting liquid from said liquid outlet means exclusively to said expansion valve; heat exchange means including separate flow paths for expanded condensate, natural gas to be liquefied, and cycle liquid; and conduit means for effecting said communications and also for recirculating resultant heated expanded condensate from said heat exchange means and said expansion valve to the inlet of said circulation compressor, and means for effecting multiple stages of partial condensation, phase separation, and expansion of resultant condensates, said mean being in communication with the outlet side of the last serially connected compression stage (8).
- 6. A process as defined by claim 1 wherein fluid entering said intercooler is cooled to about 10*-30*C. in said intercooler.
- 7. A process as defined by claim 6 wherein fluid entering said intercooler is cooled to about 20*-30*C. in said intercooler.
- 8. A process as defined by claim 2, said pressure being about 15-45 atmospheres absolute.
- 9. A process as defined by claim 8, the cycle gas entering the intercooler having the following composition in per cent by volume: 0-5 N2; 30-50 CH4; 20-50 C2H6; 10-40 C3H8; 0-15 C4H10; 0-3 C5H12; and 0-2 C6H14.
- 10. A process as defined by claim 2, said pressure being about 10-25 atmospheres absolute.
- 11. A process as defined by claim 10, the cycle gas entering the intercooler having the following composition in per cent by volume: 0.05-2 N2; 35-40 C4; 20-40 C2H6; 10-30 C3H8; 4-12 C4H10; 1-2 C5H12; and 1-2 C6H14.
- 12. A process as defined by claim 1, said refrigeration cycle being a closed cycle, the pressure entering the intercooler being 2-20 atmospheres absolute and the gas entering the intercooler having the following composition in per cent by volume: 0-10 N2; 10-40 CH4; 20-40 C2H6 or C2H4; 0-20 C3H8; 10-20 C4H10; 0-20 C5H12; and 0-20 C6H14.
- 13. A process as defined by claim 1, said refrigeration cycle being a closed cycle, the pressure entering the intercooler being 10-25 atmospheres absolute and the gas entering the intercooler having the following composition in per cent by volume: 2-6 N2; 30-40 CH4; 35-45 C2H6 or C2H4; 0-3 C3H8; 10-15 C4H10; 5-10 C5H12; and 5-10 C6H14.
- 14. A process as defined by claim 1, said liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about 40-70 and said vapor phase separated therefrom having a molecular weight of about 20-40.
- 15. A process as defined by claim 1, said liquid phase condensate having a substantial concentration of heavy hydrocarbons having a molecular weight of about 50-60 and said vapor phase separated therefrom having a molecular weight of about 20-30.
- 16. A process as defined b claim 2 comprising the steps of passing said vapor separated from said condensate having a substantial concentration of heavy hydrocarbons to a final compression stage of said multi-stage compressor; cooling resultant compressed vapor to form a liquid phase and a vapor phase; passing the just-mentioned liquid phase through a heat exchanger, and expanding a portion of resultant heat exchanged fluid and discharging the latter from said liquefaction cycle, said portion being of sufficient amount and of a composition to remove C3 and higher hydrocarbons from the natural gas intermixed with said cycle fluid.
- 17. A process as defined by claim 1, said condensate from said intercooler being employed as a cooling medium only in the higher temperature stages of said multiple stages of decreasing temperature.
Applications Claiming Priority (1)
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DE19681806879 DE1806879C3 (en) | 1968-11-04 | Process for liquefying natural gas |
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US3874184A (en) * | 1973-05-24 | 1975-04-01 | Phillips Petroleum Co | Removing nitrogen from and subsequently liquefying natural gas stream |
US3879180A (en) * | 1971-12-18 | 1975-04-22 | Gutehoffnungshuette Sterkrade | Method for treating a gas current which is obtained by coal gasification |
US3884044A (en) * | 1970-02-09 | 1975-05-20 | Exxon Research Engineering Co | Mixed refrigerant cycle |
US3884045A (en) * | 1970-02-09 | 1975-05-20 | Exxon Research Engineering Co | Mixed refrigerant cycle |
US3914949A (en) * | 1971-02-19 | 1975-10-28 | Chicago Bridge & Iron Co | Method and apparatus for liquefying gases |
US3945214A (en) * | 1973-07-03 | 1976-03-23 | Societe Des Procedes L'air Liquide Et Technip De Liquefaction Des Gaz Naturels | Method and apparatus for cooling a gas |
US4303427A (en) * | 1976-06-23 | 1981-12-01 | Heinrich Krieger | Cascade multicomponent cooling method for liquefying natural gas |
US4325231A (en) * | 1976-06-23 | 1982-04-20 | Heinrich Krieger | Cascade cooling arrangement |
US4707170A (en) * | 1986-07-23 | 1987-11-17 | Air Products And Chemicals, Inc. | Staged multicomponent refrigerant cycle for a process for recovery of C+ hydrocarbons |
US6751984B2 (en) * | 2000-02-10 | 2004-06-22 | Sinvent As | Method and device for small scale liquefaction of a product gas |
US20070283718A1 (en) * | 2006-06-08 | 2007-12-13 | Hulsey Kevin H | Lng system with optimized heat exchanger configuration |
US20090095019A1 (en) * | 2006-05-15 | 2009-04-16 | Marco Dick Jager | Method and apparatus for liquefying a hydrocarbon stream |
FR2944096A1 (en) * | 2009-04-07 | 2010-10-08 | Ass Pour La Rech Et Le Dev De | METHOD AND REFRIGERATING SYSTEM FOR RECOVERING METHANE COLOR WITH REFRIGERATED FLUIDS |
WO2010128467A2 (en) * | 2009-05-08 | 2010-11-11 | Corac Group Plc | Production and distribution of natural gas |
CN102564057A (en) * | 2011-12-19 | 2012-07-11 | 中国海洋石油总公司 | Propane pre-cooling mixed refrigerant liquefaction system applied to base-load type natural gas liquefaction factory |
CN102654346A (en) * | 2012-05-22 | 2012-09-05 | 中国海洋石油总公司 | Propane pre-cooling double-mixing refrigerant parallel-connection liquefaction system |
US20120227418A1 (en) * | 2011-03-08 | 2012-09-13 | Linde Aktiengesellschaft | Cooling unit |
EP3252408A1 (en) * | 2016-06-02 | 2017-12-06 | L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude | Method for purifying natural gas and for liquefying carbon dioxide |
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Cited By (31)
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US3884044A (en) * | 1970-02-09 | 1975-05-20 | Exxon Research Engineering Co | Mixed refrigerant cycle |
US3884045A (en) * | 1970-02-09 | 1975-05-20 | Exxon Research Engineering Co | Mixed refrigerant cycle |
US3914949A (en) * | 1971-02-19 | 1975-10-28 | Chicago Bridge & Iron Co | Method and apparatus for liquefying gases |
US3879180A (en) * | 1971-12-18 | 1975-04-22 | Gutehoffnungshuette Sterkrade | Method for treating a gas current which is obtained by coal gasification |
US3874184A (en) * | 1973-05-24 | 1975-04-01 | Phillips Petroleum Co | Removing nitrogen from and subsequently liquefying natural gas stream |
US3945214A (en) * | 1973-07-03 | 1976-03-23 | Societe Des Procedes L'air Liquide Et Technip De Liquefaction Des Gaz Naturels | Method and apparatus for cooling a gas |
US4303427A (en) * | 1976-06-23 | 1981-12-01 | Heinrich Krieger | Cascade multicomponent cooling method for liquefying natural gas |
US4325231A (en) * | 1976-06-23 | 1982-04-20 | Heinrich Krieger | Cascade cooling arrangement |
US4707170A (en) * | 1986-07-23 | 1987-11-17 | Air Products And Chemicals, Inc. | Staged multicomponent refrigerant cycle for a process for recovery of C+ hydrocarbons |
US6751984B2 (en) * | 2000-02-10 | 2004-06-22 | Sinvent As | Method and device for small scale liquefaction of a product gas |
US8578734B2 (en) * | 2006-05-15 | 2013-11-12 | Shell Oil Company | Method and apparatus for liquefying a hydrocarbon stream |
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Also Published As
Publication number | Publication date |
---|---|
FR2022550B1 (en) | 1973-12-07 |
FR2022550A1 (en) | 1970-07-31 |
DE1806879B2 (en) | 1975-10-30 |
GB1278974A (en) | 1972-06-21 |
DE1806879A1 (en) | 1970-05-27 |
JPS5440512B1 (en) | 1979-12-04 |
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