US20170153057A1 - Methods and apparatus for liquefaction of natural gas - Google Patents
Methods and apparatus for liquefaction of natural gas Download PDFInfo
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- US20170153057A1 US20170153057A1 US15/230,357 US201615230357A US2017153057A1 US 20170153057 A1 US20170153057 A1 US 20170153057A1 US 201615230357 A US201615230357 A US 201615230357A US 2017153057 A1 US2017153057 A1 US 2017153057A1
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- natural gas
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- liquefaction
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- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 title claims abstract description 307
- 239000003345 natural gas Substances 0.000 title claims abstract description 137
- 238000000034 method Methods 0.000 title claims description 35
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims abstract description 151
- 229910052757 nitrogen Inorganic materials 0.000 claims abstract description 77
- 239000007788 liquid Substances 0.000 claims abstract description 34
- 238000003860 storage Methods 0.000 abstract description 23
- 239000003949 liquefied natural gas Substances 0.000 description 62
- 230000008569 process Effects 0.000 description 20
- 239000007789 gas Substances 0.000 description 17
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- 238000001816 cooling Methods 0.000 description 11
- 229910002092 carbon dioxide Inorganic materials 0.000 description 7
- 239000001569 carbon dioxide Substances 0.000 description 7
- 238000005057 refrigeration Methods 0.000 description 7
- 241000894007 species Species 0.000 description 7
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- 238000010926 purge Methods 0.000 description 6
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 230000008859 change Effects 0.000 description 5
- 239000002808 molecular sieve Substances 0.000 description 5
- 238000012545 processing Methods 0.000 description 5
- 238000000926 separation method Methods 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 238000004891 communication Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 230000008929 regeneration Effects 0.000 description 4
- 238000011069 regeneration method Methods 0.000 description 4
- 150000002829 nitrogen Chemical class 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 3
- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 230000001066 destructive effect Effects 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 238000012552 review Methods 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- 241000196324 Embryophyta Species 0.000 description 1
- 235000018457 Gynura procumbens Nutrition 0.000 description 1
- 240000008672 Gynura procumbens Species 0.000 description 1
- 230000000274 adsorptive effect Effects 0.000 description 1
- 150000001335 aliphatic alkanes Chemical class 0.000 description 1
- 239000001273 butane Substances 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005194 fractionation Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
- 230000008014 freezing Effects 0.000 description 1
- 239000002737 fuel gas Substances 0.000 description 1
- 238000002309 gasification Methods 0.000 description 1
- 238000007726 management method Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000000203 mixture Substances 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
- 238000002203 pretreatment Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001105 regulatory effect Effects 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
- F25J1/006—Processes or apparatus for liquefying or solidifying gases or gaseous mixtures characterised by the refrigerant fluid used
- F25J1/007—Primary atmospheric gases, mixtures thereof
- F25J1/0072—Nitrogen
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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
- F25J1/0221—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 the cold stored in an external cryogenic component in an open 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
- F25J1/0243—Start-up or control of the process; Details of the apparatus used; Details of the refrigerant compression system used
- F25J1/0244—Operation; Control and regulation; Instrumentation
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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
- F25J1/0244—Operation; Control and regulation; Instrumentation
- F25J1/0245—Different modes, i.e. 'runs', of operation; Process control
- F25J1/0251—Intermittent or alternating process, so-called batch process, e.g. "peak-shaving"
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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
- F25J2205/00—Processes or apparatus using other separation and/or other processing means
- F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
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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
- F25J2205/00—Processes or apparatus using other separation and/or other processing means
- F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
- F25J2205/66—Regenerating the adsorption vessel, e.g. kind of reactivation 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
- F25J2205/00—Processes or apparatus using other separation and/or other processing means
- F25J2205/84—Processes or apparatus using other separation and/or other processing means using filter
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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
- F25J2210/00—Processes characterised by the type or other details of the feed stream
- F25J2210/42—Nitrogen
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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
- F25J2215/00—Processes characterised by the type or other details of the product stream
- F25J2215/04—Recovery of liquid products
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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
- F25J2220/66—Separating acid gases, e.g. CO2, SO2, H2S or RSH
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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
- F25J2220/68—Separating water or hydrates
Definitions
- the present invention relates to apparatus and methods for liquefying natural gas.
- the present invention relates to apparatus and methods for liquefying natural gas that allows for switching process flow from a saturated treating unit to a purged treating unit without significant loss of natural gas, and in some embodiments without any loss of natural gas.
- U.S. Patent Application Publication No. 20050217314 by Baudat, published October 6, 2005 discloses an apparatus for and process for recovering LNG from reservoir natural gas which includes circulating a portion of the natural gas thru a gas cooling loop that includes heat exchanges, an expansion zone and compression zone. The process also includes removing liquids from the gas cooling loop, distilling those liquids to recover a distilled gas. The process also includes compressing and expanding various portions of the distilled gas and passing those portions thru heat exchangers shared with the gas cooling loop to effect heating/cooling as desired. The process also includes removing a portion of the LNG cooling loop as LNG product.
- U.S. Pat. No. 7,325,415 to Amin et al. discloses novel processes and devices for the removal of freezable species such as carbon dioxide, water and heavy hydrocarbons from a natural gas feed stream during liquefaction to produce LNG are disclosed.
- the freezable species are able to be removed as a solid, avoiding the costly step of pretreatment to remove the freezable species from the natural gas feed stream prior to the liquefaction stage.
- the freezable species may be removed on a continuous basis being separated as solids following liquefaction of the natural gas feed stream with subsequent separation of the solids.
- the solid freezable species may then be liquefied on a continuous basis if required with natural gas recycled to the process.
- At least part of the cooling vessel is constructed from a material having a low thermal conductivity which discourages formation of the solids of the freezable species on the walls of the cooling vessel.
- U.S. Patent Application Publication No. 20110265494 by Barclay, published Nov. 3, 2011 discloses a liquefied natural gas production and storage scheme for offshore liquefaction of stranded gas reserves using a processing vessel and a liquefaction and storage shuttle vessel.
- the processing vessel includes the typical steps of condensate management, pre-treatment and compression.
- the processing vessel also recompresses a recycle gas from the LNG production and storage vessel.
- the high pressure, treated natural gas is fed to the LNG production and storage vessel that has minimal processing equipment consisting of at least a heat exchanger, an isentropic expander, a separator vessel, and a small LP compressor.
- the liquefier on the liquefaction and storage vessel are designed to generate a high liquid yield without the need for excessive operating pressures or multiple refrigerants circulating between vessels.
- U.S. Patent Application Publication No. 20140130542 by Brown et al discloses a novel method and system for liquefying and distilling natural gas into high purity liquid methane (LNG) and NGL product streams.
- Heat exchangers and distillation towers are configured to produce high purity liquefied natural gas (LNG) and NGL product streams, while also rejecting excess nitrogen contained in the inlet gas stream, utilizing liquid nitrogen as the process refrigerant.
- a molecular sieve pretreatment system is configured to utilize the vaporized nitrogen stream for regeneration of the molecular sieve beds which are designed for removing water and carbon dioxide from the inlet gas stream.
- the facility comprises a gas separation unit having at least one fractionation vessel.
- the gas separation unit employs adsorbent beds for adsorptive kinetic separation.
- the adsorbent beds release a methane-rich gas feed stream.
- the facility also includes a high-pressure expander cycle refrigeration system.
- the refrigeration system compresses the methane-rich gas feed stream to a pressure greater than about 1,000 psia.
- the refrigeration system also chills the methane-rich gas feed stream in one or more coolers, and then expands the chilled gas feed stream to form a liquefied product stream.
- Processes for liquefying a natural gas feed stream using AKS and a high-pressure expander cycle refrigeration system are also provided herein. Such processes allow for the formation of LNG using a facility having less weight than conventional facilities.
- U.S. Patent Application Publication No. 20150276307 published by Ohart et al. on Oct. 1, 2015, discloses a method for producing liquefied natural gas (LNG) and separating natural gas liquids (NGLs) from the LNG.
- the method may include compressing natural gas to compressed natural gas, removing a non-hydrocarbon from the compressed natural gas, and cooling the compressed natural gas to a cooled, compressed natural gas.
- the method may also include expanding a first portion and a second portion of the cooled, compressed natural gas in a first expansion element and a second expansion element to generate a first refrigeration stream and a second refrigeration stream, respectively.
- the method may further include separating a third portion of the cooled, compressed natural gas into a methane lean natural gas fraction containing the NGLs and a methane rich natural gas fraction.
- the methane rich natural gas fraction may be cooled in a liquefaction assembly with the first and second refrigeration streams to thereby produce the LNG.
- a natural gas liquefaction apparatus may include associated piping and valves that interconnect one or more of the following: a natural gas inlet stream; a liquid nitrogen stream; a first treating unit; a second treating unit; a changeover treating unit; a liquefaction unit; and, an LNG product stream.
- the associated piping defines a first operating phase flow path for natural gas from the natural gas inlet stream to the first treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the second treating unit.
- the associated piping defines a second operating phase flow path for natural gas from the natural gas inlet stream to the second treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the first treating unit.
- the associated piping defines a changeover flow path for the natural gas from the natural gas inlet stream to the changeover treating unit to the liquefaction unit to the LNG product stream.
- a method of liquefying natural gas may include the steps of:
- FIG. 1 is a schematic flow diagram showing natural gas liquefaction system 10 of the present invention for condensing natural gas 100 into liquefied natural gas (“LNG”), which in the non-limiting embodiment shown may include treating unit 500 , treating unit 600 , liquefaction heat exchanger 700 , change over unit 800 , liquid nitrogen tank 200 , LNG product storage 300 , and pressure build unit 210 .
- LNG liquefied natural gas
- the methods, apparatus and products of the present invention may be utilized to liquefy natural gas to form liquefied natural gas (“LNG”).
- LNG liquefied natural gas
- the present invention relates to apparatus and methods for turning natural gas into liquefied natural gas (“LNG”).
- LNG is natural gas (predominantly methane with some mixture of ethane) that has been converted to liquid form for ease of storage or transport.
- LNG takes up about 1/600th the volume of natural gas in the gaseous state.
- natural gas liquefaction system 10 of the present invention for condensing natural gas 100 into liquefied natural gas (“LNG”), which in the non-limiting embodiment shown may include treating unit 500 , treating unit 600 , liquefaction heat exchanger 700 , change over unit 800 , liquid nitrogen tank 200 , LNG product storage 300 , and pressure build unit 210 .
- LNG liquefied natural gas
- Natural gas 100 is provided to system 10 through value 34 . It should be understood that natural gas 100 fed into LNG plant 10 must be treated to remove at least water, carbon dioxide, and/or any other components that will freeze (e.g., benzene) under the low temperatures needed for storage or be destructive to the liquefaction facility. LNG typically contains more than 90 percent methane. It also contains small amounts of ethane, propane, butane, some heavier alkanes, and nitrogen. The purification process can be designed to give almost 100 percent methane.
- Treating unit 500 , treating unit 600 and change over unit 800 serve to treat the natural gas and remove the carbon dioxide, water and other components in the natural gas as required.
- the water content of the natural gas needs to be reduced to very low values (less than 1 ppmv) to prevent it from freezing and causing blockages during operation.
- treating unit 500 and treating unit 600 are partitioned bed molecular sieve units with treating capacity that may be on the order of 8 hours, with changeover unit 800 having a treating capacity on the order of 15 minutes.
- treating capacity of these units may vary depending upon operating conditions, design parameters and/or economics, but in general, treating unit 500 and treating unit 600 will have rather treating capacity whereas the changeover unit 800 will have a treating capacity a very small fraction of those units.
- changeover unit will have a capacity that is sufficient to allow time for changeover between treating units 500 and 600 plus optionally some built in contingency time.
- the liquefaction unit 10 operates alternatively between treating unit 500 and treating unit 600 . During the short changeover between treating unit 500 and treating unit 600 , process flow is routed through changeover unit 800 prior to being switched to the other treating unit.
- system 10 also includes pairs of larger diameter valves (generally 3 inches) paired with smaller diameter valves (generally 3 ⁇ 4 inch), specifically, 3 inch valves 21 , 22 , 24 and 25 , paired respectively with 3 ⁇ 4 inch valves 66 , 67 , 68 and 69 .
- larger diameter valves generally 3 inches
- smaller diameter valves generally 3 ⁇ 4 inch
- 3 inch valves 21 , 22 , 24 and 25 paired respectively with 3 ⁇ 4 inch valves 66 , 67 , 68 and 69 .
- any suitable sizes of valves may be utilized depending upon the process parameters and economics.
- a single flow lone having a variable flow valve may be utilized instead of this parallel stream process.
- Treating unit 500 Normal operation though treating unit 500 is as follows. Natural gas 100 enters system 10 through valve 34 and will be routed to treating unit 500 .
- Override selector 37 is in communication with flow controller 33 , pressure controller 35 , pressure controller 36 , valve 36 and valve 38 .
- the natural gas flow path will be from the inlet through treating unit 500 on to the liquefaction unit 700 where it is converted into LNG and then onto LNG product storage tank 300 , with all valves set to accomplish this.
- the nitrogen flow path will be from liquid nitrogen tank 200 through liquefaction unit 700 and onto and through treating unit 600 and/or changeover unit 800 and ultimately though the vent, with all valves set to accomplish this.
- treating unit 500 will be full of nitrogen, so natural gas 100 is initially provided to treating unit 500 through the smaller valve 66 to push out any remaining nitrogen through valve 62 and vent valve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once up and going, natural gas 100 is provided to treating unit 500 through the larger valve 21 .
- the treated natural gas flows through valve 23 and into liquefaction unit 700 when the natural gas is liquefied into LNG.
- Pump 310 may be utilized to assist in transporting LNG product to its next destination, whether that be a pipeline or a tank or another operating unit.
- liquid nitrogen flows from liquid nitrogen tank 200 through valve 12 and toward liquefaction unit 700 .
- the liquid nitrogen is pressured to about 75 to 115 psig with pressure build unit PBU 210 by operating pressure control valve 11 V in communication with controller 11 C.
- the pressurized liquid nitrogen passes through control valve 31 V and into liquefaction unit 700 where latent and sensible heat is exchanged between the natural gas and the nitrogen to cool and condense the natural gas and vaporize the nitrogen.
- Valve 31 V controls the flow of liquid nitrogen into liquefaction unit 700 , with valve 31 V being controlled by temperature controller 31 C on the LNG line exiting liquefaction unit 700 .
- Nitrogen exiting liquefaction unit 700 then passes though optional heat exchanger 160 then onto treating unit 600 and/or changeover unit 800 .
- treating unit 600 When making a changeover, treating unit 600 will be full of natural gas, so nitrogen is provided through smaller valve 69 to purge the natural gas to liquefaction unit 700 where it is liquefied and then routed to LNG product storage tank 300 .
- regeneration of treating unit 600 to remove water, carbon and other components is accomplished by heating the nitrogen exiting liquefaction unit 700 with heat exchanger 160 and providing that heated nitrogen to treating unit 600 through large valve 25 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exit unit 600 and ultimately pass through valve 61 and vent valve 65 to vent.
- Nitrogen is also provided to changeover unit 800 .
- First it is provided through valve 43 to purge any natural gas from unit 800 out through valve 42 on its way to LNG product storage tank 300 .
- Second nitrogen heated by heat exchanger 160 is provided through valve 43 to regenerate treating unit 600 to remove water, carbon and other components adsorbed from the natural gas.
- treating unit 500 approaches being saturated with carbon dioxide, at which time it is advisable to switch operations over to treating unit 600 .
- This is accomplished to shutting down treating unit 500 , utilizing changeover unit 800 during the change over, and starting up and switching over to treating unit 600 .
- the incoming natural gas 100 ceases to be provided to treating unit 500 and is then routed though valve 41 to changeover unit 800 where the natural gas is treated to remove at least water, carbon dioxide, and/or any other components that will freeze (e.g., benzene) under the low temperatures needed for storage or be destructive to the liquefaction facility.
- natural gas is utilized to purge nitrogen in treating unit 800 out through valve 44 and value vent 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas.
- natural gas exiting changeover unit 800 travels through valve 42 to liquefaction unit 700 where it is cooled into LNG. This LNG then travels through valve 38 to LNG storage tank 300 .
- the flow of natural gas through changeover unit 800 will continue until treating unit 600 is up and running and treating natural.
- This flow through unit 800 during the changeover from unit 500 to unit 600 serves to maintain a minimum flow through the system to keep all equipment at the operating temperatures and pressures and reduce energy consumption.
- natural gas is also routed to treating unit 600 .
- treating unit 600 will be full of nitrogen, so natural gas 100 is initially provided to treating unit 600 through the smaller valve 67 to push out any remaining nitrogen through valve 61 and vent valve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas.
- natural gas 100 is provided to treating unit 600 through the larger valve 22 .
- nitrogen is routed to treating unit 500 .
- treating unit 500 will be full of natural gas, so nitrogen is provided through smaller valve 68 to purge the natural gas to liquefaction unit 700 where it is liquefied and then routed to LNG product storage tank 300 .
- regeneration of treating unit 500 to remove water, carbon and other components is accomplished by heating the nitrogen exiting liquefaction unit 700 with heat exchanger 160 and providing that heated nitrogen to treating unit 500 through large valve 24 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exit unit 500 and ultimately pass through valve 62 and vent valve 65 to vent.
- Treating unit 600 Normal operation though treating unit 600 is essentially the same as through treating unit 500 , except that the roles of units 500 and 600 have been reversed, and is as follows. Natural gas 100 enters system 10 through valve 34 and will be routed to treating unit 600 .
- Override selector 37 is in communication with flow controller 33 , pressure controller 35 , pressure controller 36 , valve 36 and valve 38 .
- the natural gas flow path will be from the inlet through treating unit 600 on to the liquefaction unit 700 where it is converted into LNG and then onto LNG product storage tank 300 , with all valves set to accomplish this.
- the nitrogen flow path will be from liquid nitrogen tank 200 through liquefaction unit 700 and onto and through treating unit 500 and/or changeover unit 800 and ultimately though the vent, with all valves set to accomplish this.
- treating unit 600 will be full of nitrogen, so natural gas 100 is initially provided to treating unit 600 through the smaller valve 67 to push out any remaining nitrogen through valve 61 and vent valve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once up and going, natural gas 100 is provided to treating unit 600 through the larger valve 22 .
- the treated natural gas flows through valve 26 and into liquefaction unit 700 when the natural gas is liquefied into LNG.
- Pump 310 may be utilized to assist in transporting LNG product to its next destination, whether that be a pipeline or a tank or another operating unit.
- liquid nitrogen flows from liquid nitrogen tank 200 through valve 12 and toward liquefaction unit 700 .
- the liquid nitrogen is pressured to about 75 to 115 psig with pressure build unit PBU 210 by operating pressure control valve 11 V in communication with controller 11 C.
- the pressurized liquid nitrogen passes through control valve 31 V and into liquefaction unit 700 where latent and sensible heat is exchanged between the natural gas and the nitrogen to cool and condense the natural gas and vaporize the nitrogen.
- Valve 31 V controls the flow of liquid nitrogen into liquefaction unit 700 , with valve 31 V being controlled by temperature controller 31 C on the LNG line exiting liquefaction unit 700 .
- Nitrogen exiting liquefaction unit 700 then passes though optional heat exchanger 160 then onto treating unit 500 and/or changeover unit 800 .
- treating unit 500 When making a changeover, treating unit 500 will be full of natural gas, so nitrogen is provided through smaller valve 68 to purge the natural gas to liquefaction unit 700 where it is liquefied and then routed to LNG product storage tank 300 .
- regeneration of treating unit 500 to remove water, carbon and other components is accomplished by heating the nitrogen exiting liquefaction unit 700 with heat exchanger 160 and providing that heated nitrogen to treating unit 500 through large valve 24 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exit unit 500 and ultimately pass through valve 61 and vent valve 65 to vent.
- Nitrogen is also provided to changeover unit 800 .
- First it is provided through valve 43 to purge any natural gas from unit 800 out through valve 42 on its way to LNG product storage tank 300 .
- Second nitrogen heated by heat exchanger 160 is provided through valve 43 to regenerate treating unit 500 to remove water, carbon and other components adsorbed from the natural gas.
- treating unit 600 approaches being saturated with carbon dioxide, at which time it is advisable to switch operations back over to treating unit 500 .
- the liquefaction process is continued in this fashion of alternating natural gas treatment back and forth between treating unit 500 and treating unit 600 , with use of the changeover unit 800 all as described above.
Abstract
A liquefaction unit that may include a first treating unit, a second treating unit, a liquefaction heat exchanger, a changeover unit, a liquid nitrogen tank, an LNG product storage tank, and a pressure build unit. During a first operating phase, the associated piping defines a first operating phase flow path for natural gas from the natural gas inlet stream to the first treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the second treating unit. During a second operating phase, the associated piping defines a second operating phase flow path for natural gas from the natural gas inlet stream to the second treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the first treating unit. During a changeover operating phase, the associated piping defines a changeover flow path for the natural gas from the natural gas inlet stream to the changeover treating unit to the liquefaction unit to the LNG product stream.
Description
- This patent application claims priority of U.S. Provisional Patent Application No. 62/201,377, filed Aug. 5, 2015, which is herein incorporated by reference.
- 1. Field of the Invention
- The present invention relates to apparatus and methods for liquefying natural gas. In another aspect, the present invention relates to apparatus and methods for liquefying natural gas that allows for switching process flow from a saturated treating unit to a purged treating unit without significant loss of natural gas, and in some embodiments without any loss of natural gas.
- 2. Description of the Related Art
- There are numerous patents and publications relating to liquefaction of natural gas to form LNG of which the following are merely a few.
- U.S. Patent Application Publication No. 20030154739 by Fanning et al., published Aug. 21, 2003, discloses natural gas liquefaction systems are provided wherein dependent trains including only cryogenic heat exchanger systems are serviced by common components in the system such that individual components need not be included in each dependent train for servicing that function. Further, the common components are positioned near the LNG storage tanks which, in turn, are typically located a substantial distance from the trains. This significantly reduces capital costs and allows boil-off gas from LNG storage tanks to be used for cooling in addition to being used as a fuel gas.
- U.S. Patent Application Publication No. 20050217314 by Baudat, published October 6, 2005, discloses an apparatus for and process for recovering LNG from reservoir natural gas which includes circulating a portion of the natural gas thru a gas cooling loop that includes heat exchanges, an expansion zone and compression zone. The process also includes removing liquids from the gas cooling loop, distilling those liquids to recover a distilled gas. The process also includes compressing and expanding various portions of the distilled gas and passing those portions thru heat exchangers shared with the gas cooling loop to effect heating/cooling as desired. The process also includes removing a portion of the LNG cooling loop as LNG product.
- U.S. Pat. No. 7,325,415 to Amin et al., issued Feb. 5, 2008, discloses novel processes and devices for the removal of freezable species such as carbon dioxide, water and heavy hydrocarbons from a natural gas feed stream during liquefaction to produce LNG are disclosed. The freezable species are able to be removed as a solid, avoiding the costly step of pretreatment to remove the freezable species from the natural gas feed stream prior to the liquefaction stage. The freezable species may be removed on a continuous basis being separated as solids following liquefaction of the natural gas feed stream with subsequent separation of the solids. The solid freezable species may then be liquefied on a continuous basis if required with natural gas recycled to the process. Continuous removal of the freezable species from the natural gas feed stream is achievable by maintaining cooling and separation apparatus at the same working pressure. Advantageously, at least part of the cooling vessel is constructed from a material having a low thermal conductivity which discourages formation of the solids of the freezable species on the walls of the cooling vessel.
- U.S. Patent Application Publication No. 20110265494 by Barclay, published Nov. 3, 2011 discloses a liquefied natural gas production and storage scheme for offshore liquefaction of stranded gas reserves using a processing vessel and a liquefaction and storage shuttle vessel. The processing vessel includes the typical steps of condensate management, pre-treatment and compression. The processing vessel also recompresses a recycle gas from the LNG production and storage vessel. The high pressure, treated natural gas is fed to the LNG production and storage vessel that has minimal processing equipment consisting of at least a heat exchanger, an isentropic expander, a separator vessel, and a small LP compressor. The liquefier on the liquefaction and storage vessel are designed to generate a high liquid yield without the need for excessive operating pressures or multiple refrigerants circulating between vessels.
- U.S. Patent Application Publication No. 20140130542 by Brown et al, published May 15, 2014, discloses a novel method and system for liquefying and distilling natural gas into high purity liquid methane (LNG) and NGL product streams. Heat exchangers and distillation towers are configured to produce high purity liquefied natural gas (LNG) and NGL product streams, while also rejecting excess nitrogen contained in the inlet gas stream, utilizing liquid nitrogen as the process refrigerant. A molecular sieve pretreatment system is configured to utilize the vaporized nitrogen stream for regeneration of the molecular sieve beds which are designed for removing water and carbon dioxide from the inlet gas stream.
- U.S. Patent Application Publication No. 20140208797 by Kelley et al., published on Jul. 31, 2014, discloses a gas processing facility for the liquefaction of a natural gas feed stream is provided. The facility comprises a gas separation unit having at least one fractionation vessel. The gas separation unit employs adsorbent beds for adsorptive kinetic separation. The adsorbent beds release a methane-rich gas feed stream. The facility also includes a high-pressure expander cycle refrigeration system. The refrigeration system compresses the methane-rich gas feed stream to a pressure greater than about 1,000 psia. The refrigeration system also chills the methane-rich gas feed stream in one or more coolers, and then expands the chilled gas feed stream to form a liquefied product stream. Processes for liquefying a natural gas feed stream using AKS and a high-pressure expander cycle refrigeration system are also provided herein. Such processes allow for the formation of LNG using a facility having less weight than conventional facilities.
- U.S. Patent Application Publication No. 20150276307, published by Ohart et al. on Oct. 1, 2015, discloses a method for producing liquefied natural gas (LNG) and separating natural gas liquids (NGLs) from the LNG. The method may include compressing natural gas to compressed natural gas, removing a non-hydrocarbon from the compressed natural gas, and cooling the compressed natural gas to a cooled, compressed natural gas. The method may also include expanding a first portion and a second portion of the cooled, compressed natural gas in a first expansion element and a second expansion element to generate a first refrigeration stream and a second refrigeration stream, respectively. The method may further include separating a third portion of the cooled, compressed natural gas into a methane lean natural gas fraction containing the NGLs and a methane rich natural gas fraction. The methane rich natural gas fraction may be cooled in a liquefaction assembly with the first and second refrigeration streams to thereby produce the LNG.
- U.S. Patent Application Publication 20160047597, published by Brett et al. on Feb. 18, 2016, discloses methods and apparatus for the efficient cooling within air liquefaction processes with integrated use of cold recovery from an adjacent LNG gasification process are disclosed.
- In spite of the many advances in the prior art, there are still needs in the art for methods and apparatus for liquefying natural gas.
- These and other needs in the art will become apparent to those of skill in the art upon review of this specification, including its drawings and claims.
- It is an object of the present invention to provide for methods and apparatus for liquefying natural gas.
- According to one embodiment of the present invention there is provided a natural gas liquefaction apparatus that may include associated piping and valves that interconnect one or more of the following: a natural gas inlet stream; a liquid nitrogen stream; a first treating unit; a second treating unit; a changeover treating unit; a liquefaction unit; and, an LNG product stream. During a first operating phase, the associated piping defines a first operating phase flow path for natural gas from the natural gas inlet stream to the first treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the second treating unit. During a second operating phase, the associated piping defines a second operating phase flow path for natural gas from the natural gas inlet stream to the second treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the first treating unit. And, during a changeover operating phase, the associated piping defines a changeover flow path for the natural gas from the natural gas inlet stream to the changeover treating unit to the liquefaction unit to the LNG product stream.
- According to another embodiment of the present invention, these is provided, a method of liquefying natural gas. The method may include the steps of:
- During a first operating stage, flowing the natural gas to a first treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG, and flowing liquid nitrogen to the liquefaction unit and then to a second treating unit;
- During a second operating stage, flowing the natural gas to the second treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG, and flowing liquid nitrogen to the liquefaction unit and then to the first treating unit; and/or,
- During a changeover operating stage, flowing the natural gas the a changeover treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG.
- These and other embodiments are readily apparent to those of skill in the art upon review of this disclosure.
- The following drawing illustrates some of the many possible embodiments of this disclosure in order to provide a basic understanding of this disclosure. The drawing does not provide an extensive overview of all embodiments of this disclosure. The drawing is not intended to identify key or critical elements of the disclosure or to delineate or otherwise limit the scope of the claims. The following draw merely present some concepts of the disclosure in a general form. Thus, for a detailed understanding of this disclosure, reference should be made to the following detailed description, taken in conjunction with the accompanying drawing, in which like elements have been given like numerals.
-
FIG. 1 is a schematic flow diagram showing natural gas liquefaction system 10 of the present invention for condensingnatural gas 100 into liquefied natural gas (“LNG”), which in the non-limiting embodiment shown may include treatingunit 500, treatingunit 600,liquefaction heat exchanger 700, change overunit 800,liquid nitrogen tank 200,LNG product storage 300, andpressure build unit 210. - The methods, apparatus and products of the present invention may be utilized to liquefy natural gas to form liquefied natural gas (“LNG”).
- The present invention relates to apparatus and methods for turning natural gas into liquefied natural gas (“LNG”). LNG is natural gas (predominantly methane with some mixture of ethane) that has been converted to liquid form for ease of storage or transport. Generally, LNG takes up about 1/600th the volume of natural gas in the gaseous state.
- Referring now to
FIG. 1 , there is shown natural gas liquefaction system 10 of the present invention for condensingnatural gas 100 into liquefied natural gas (“LNG”), which in the non-limiting embodiment shown may include treatingunit 500, treatingunit 600,liquefaction heat exchanger 700, change overunit 800,liquid nitrogen tank 200,LNG product storage 300, andpressure build unit 210. -
Natural gas 100 is provided to system 10 throughvalue 34. It should be understood thatnatural gas 100 fed into LNG plant 10 must be treated to remove at least water, carbon dioxide, and/or any other components that will freeze (e.g., benzene) under the low temperatures needed for storage or be destructive to the liquefaction facility. LNG typically contains more than 90 percent methane. It also contains small amounts of ethane, propane, butane, some heavier alkanes, and nitrogen. The purification process can be designed to give almost 100 percent methane. - Treating
unit 500, treatingunit 600 and change overunit 800 serve to treat the natural gas and remove the carbon dioxide, water and other components in the natural gas as required. Usually, the water content of the natural gas needs to be reduced to very low values (less than 1 ppmv) to prevent it from freezing and causing blockages during operation. - In
FIG. 1 as shown, treatingunit 500 and treatingunit 600 are partitioned bed molecular sieve units with treating capacity that may be on the order of 8 hours, withchangeover unit 800 having a treating capacity on the order of 15 minutes. Certainly, the treating capacity of these units may vary depending upon operating conditions, design parameters and/or economics, but in general, treatingunit 500 and treatingunit 600 will have rather treating capacity whereas thechangeover unit 800 will have a treating capacity a very small fraction of those units. Generally, changeover unit will have a capacity that is sufficient to allow time for changeover between treatingunits - The liquefaction unit 10 operates alternatively between treating
unit 500 and treatingunit 600. During the short changeover between treatingunit 500 and treatingunit 600, process flow is routed throughchangeover unit 800 prior to being switched to the other treating unit. - To assist in regulating the process flow, system 10 also includes pairs of larger diameter valves (generally 3 inches) paired with smaller diameter valves (generally ¾ inch), specifically, 3
inch valves inch valves - Normal Operation Through Treating
Unit 500 - Normal operation though treating
unit 500 is as follows.Natural gas 100 enters system 10 throughvalve 34 and will be routed to treatingunit 500. Override selector 37 is in communication withflow controller 33,pressure controller 35, pressure controller 36, valve 36 and valve 38. - The natural gas flow path will be from the inlet through treating
unit 500 on to theliquefaction unit 700 where it is converted into LNG and then onto LNGproduct storage tank 300, with all valves set to accomplish this. The nitrogen flow path will be fromliquid nitrogen tank 200 throughliquefaction unit 700 and onto and through treatingunit 600 and/orchangeover unit 800 and ultimately though the vent, with all valves set to accomplish this. - At startup after a changeover, treating
unit 500 will be full of nitrogen, sonatural gas 100 is initially provided to treatingunit 500 through thesmaller valve 66 to push out any remaining nitrogen throughvalve 62 and ventvalve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once up and going,natural gas 100 is provided to treatingunit 500 through thelarger valve 21. - Upon exiting treating
unit 500, the treated natural gas flows throughvalve 23 and intoliquefaction unit 700 when the natural gas is liquefied into LNG. - Upon exiting
liquefaction unit 700, the LNG passes throughvalve 33 and into LNGproduct storage tank 300. Pump 310 may be utilized to assist in transporting LNG product to its next destination, whether that be a pipeline or a tank or another operating unit. - At the same time that natural gas is making its way through system 10, liquid nitrogen flows from
liquid nitrogen tank 200 throughvalve 12 and towardliquefaction unit 700. The liquid nitrogen is pressured to about 75 to 115 psig with pressurebuild unit PBU 210 by operating pressure control valve 11V in communication with controller 11C. The pressurized liquid nitrogen passes through control valve 31V and intoliquefaction unit 700 where latent and sensible heat is exchanged between the natural gas and the nitrogen to cool and condense the natural gas and vaporize the nitrogen. Valve 31V controls the flow of liquid nitrogen intoliquefaction unit 700, with valve 31V being controlled by temperature controller 31C on the LNG line exitingliquefaction unit 700. Nitrogen exitingliquefaction unit 700 then passes thoughoptional heat exchanger 160 then onto treatingunit 600 and/orchangeover unit 800. - When making a changeover, treating
unit 600 will be full of natural gas, so nitrogen is provided through smaller valve 69 to purge the natural gas toliquefaction unit 700 where it is liquefied and then routed to LNGproduct storage tank 300. After the natural gas is purged from treatingunit 600, regeneration of treatingunit 600 to remove water, carbon and other components is accomplished by heating the nitrogen exitingliquefaction unit 700 withheat exchanger 160 and providing that heated nitrogen to treatingunit 600 throughlarge valve 25 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exitunit 600 and ultimately pass throughvalve 61 and ventvalve 65 to vent. - Nitrogen is also provided to
changeover unit 800. First it is provided through valve 43 to purge any natural gas fromunit 800 out throughvalve 42 on its way to LNGproduct storage tank 300. Second nitrogen heated byheat exchanger 160 is provided through valve 43 to regenerate treatingunit 600 to remove water, carbon and other components adsorbed from the natural gas. - The process will continue in this fashion until treating
unit 500 approaches being saturated with carbon dioxide, at which time it is advisable to switch operations over to treatingunit 600. This is accomplished to shutting down treatingunit 500, utilizingchangeover unit 800 during the change over, and starting up and switching over to treatingunit 600. - Changeover Process
- In the changeover, the incoming
natural gas 100 ceases to be provided to treatingunit 500 and is then routed thoughvalve 41 tochangeover unit 800 where the natural gas is treated to remove at least water, carbon dioxide, and/or any other components that will freeze (e.g., benzene) under the low temperatures needed for storage or be destructive to the liquefaction facility. Initially, natural gas is utilized to purge nitrogen in treatingunit 800 out throughvalve 44 and value vent 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once the nitrogen is purged out, natural gas exitingchangeover unit 800 travels throughvalve 42 toliquefaction unit 700 where it is cooled into LNG. This LNG then travels through valve 38 toLNG storage tank 300. The flow of natural gas throughchangeover unit 800 will continue until treatingunit 600 is up and running and treating natural. This flow throughunit 800 during the changeover fromunit 500 tounit 600 serves to maintain a minimum flow through the system to keep all equipment at the operating temperatures and pressures and reduce energy consumption. - In the changeover, natural gas is also routed to treating
unit 600. Initially, treatingunit 600 will be full of nitrogen, sonatural gas 100 is initially provided to treatingunit 600 through thesmaller valve 67 to push out any remaining nitrogen throughvalve 61 and ventvalve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once up and going,natural gas 100 is provided to treatingunit 600 through thelarger valve 22. - In the changeover, nitrogen is routed to treating
unit 500. Initially, treatingunit 500 will be full of natural gas, so nitrogen is provided through smaller valve 68 to purge the natural gas toliquefaction unit 700 where it is liquefied and then routed to LNGproduct storage tank 300. After the natural gas is purged from treatingunit 500, regeneration of treatingunit 500 to remove water, carbon and other components is accomplished by heating the nitrogen exitingliquefaction unit 700 withheat exchanger 160 and providing that heated nitrogen to treatingunit 500 throughlarge valve 24 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exitunit 500 and ultimately pass throughvalve 62 and ventvalve 65 to vent. - Normal Operation Through Treating
Unit 600 - Normal operation though treating
unit 600 is essentially the same as through treatingunit 500, except that the roles ofunits Natural gas 100 enters system 10 throughvalve 34 and will be routed to treatingunit 600. Override selector 37 is in communication withflow controller 33,pressure controller 35, pressure controller 36, valve 36 and valve 38. - The natural gas flow path will be from the inlet through treating
unit 600 on to theliquefaction unit 700 where it is converted into LNG and then onto LNGproduct storage tank 300, with all valves set to accomplish this. The nitrogen flow path will be fromliquid nitrogen tank 200 throughliquefaction unit 700 and onto and through treatingunit 500 and/orchangeover unit 800 and ultimately though the vent, with all valves set to accomplish this. - At startup after a changeover, treating
unit 600 will be full of nitrogen, sonatural gas 100 is initially provided to treatingunit 600 through thesmaller valve 67 to push out any remaining nitrogen throughvalve 61 and ventvalve 65 to vent. Care is taken not to vent out any natural gas even if that means that some nitrogen may remain in the system with the natural gas. Once up and going,natural gas 100 is provided to treatingunit 600 through thelarger valve 22. - Upon exiting treating
unit 600, the treated natural gas flows throughvalve 26 and intoliquefaction unit 700 when the natural gas is liquefied into LNG. - Upon exiting
liquefaction unit 700, the LNG passes throughvalve 33 and into LNGproduct storage tank 300. Pump 310 may be utilized to assist in transporting LNG product to its next destination, whether that be a pipeline or a tank or another operating unit. - At the same time that natural gas is making its way through system 10, liquid nitrogen flows from
liquid nitrogen tank 200 throughvalve 12 and towardliquefaction unit 700. The liquid nitrogen is pressured to about 75 to 115 psig with pressurebuild unit PBU 210 by operating pressure control valve 11V in communication with controller 11C. The pressurized liquid nitrogen passes through control valve 31V and intoliquefaction unit 700 where latent and sensible heat is exchanged between the natural gas and the nitrogen to cool and condense the natural gas and vaporize the nitrogen. Valve 31V controls the flow of liquid nitrogen intoliquefaction unit 700, with valve 31V being controlled by temperature controller 31C on the LNG line exitingliquefaction unit 700. Nitrogen exitingliquefaction unit 700 then passes thoughoptional heat exchanger 160 then onto treatingunit 500 and/orchangeover unit 800. - When making a changeover, treating
unit 500 will be full of natural gas, so nitrogen is provided through smaller valve 68 to purge the natural gas toliquefaction unit 700 where it is liquefied and then routed to LNGproduct storage tank 300. After the natural gas is purged from treatingunit 500, regeneration of treatingunit 500 to remove water, carbon and other components is accomplished by heating the nitrogen exitingliquefaction unit 700 withheat exchanger 160 and providing that heated nitrogen to treatingunit 500 throughlarge valve 24 where it will heat molecular sieves and remove water, nitrogen and other components that were adsorbed from the natural gas in the last cycle. This nitrogen will then exitunit 500 and ultimately pass throughvalve 61 and ventvalve 65 to vent. - Nitrogen is also provided to
changeover unit 800. First it is provided through valve 43 to purge any natural gas fromunit 800 out throughvalve 42 on its way to LNGproduct storage tank 300. Second nitrogen heated byheat exchanger 160 is provided through valve 43 to regenerate treatingunit 500 to remove water, carbon and other components adsorbed from the natural gas. - The process will continue in this fashion until treating
unit 600 approaches being saturated with carbon dioxide, at which time it is advisable to switch operations back over to treatingunit 500. This is accomplished to shutting down treatingunit 600, utilizingchangeover unit 800 during the change over, and starting up and switching over to treatingunit 500. - The liquefaction process is continued in this fashion of alternating natural gas treatment back and forth between treating
unit 500 and treatingunit 600, with use of thechangeover unit 800 all as described above. - All patents and patent publications cited in this application are herein incorporated by reference.
- The present disclosure is to be taken as illustrative rather than as limiting the scope or nature of the claims below. Numerous modifications and variations will become apparent to those skilled in the art after studying the disclosure, including use of equivalent functional and/or structural substitutes for elements described herein, use of equivalent functional couplings for couplings described herein, and/or use of equivalent functional actions for actions described herein. Any insubstantial variations are to be considered within the scope of the claims below.
Claims (2)
1. A natural gas liquefaction apparatus comprising:
associated piping and valves that interconnect the following:
a natural gas inlet stream;
a liquid nitrogen stream;
a first treating unit;
a second treating unit;
a changeover treating unit;
a liquefaction unit; and,
a LNG product stream;
wherein during a first operating phase, the associated piping defines a first operating phase flow path for natural gas from the natural gas inlet stream to the first treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the second treating unit;
wherein during a second operating phase, the associated piping defines a second operating phase flow path for natural gas from the natural gas inlet stream to the second treating unit to the liquefaction unit to the LNG product stream, and a first operating phase flow path for nitrogen from the liquid nitrogen stream to the liquefaction unit to the first treating unit; and,
wherein during a changeover operating phase, the associated piping defines a changeover flow path for the natural gas from the natural gas inlet stream to the changeover treating unit to the liquefaction unit to the LNG product stream.
2. A method of liquefying natural gas comprising the steps of:
During a first operating stage, flowing the natural gas to a first treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG, and flowing liquid nitrogen to the liquefaction unit and then to a second treating unit;
During a second operating stage, flowing the natural gas to the second treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG, and flowing liquid nitrogen to the liquefaction unit and then to the first treating unit; and,
During a changeover operating stage, flowing the natural gas a changeover treating unit to form treated natural gas, flowing the treated natural gas to the liquefaction unit to form LNG.
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US201562201377P | 2015-08-05 | 2015-08-05 | |
US15/230,357 US20170153057A1 (en) | 2015-08-05 | 2016-08-05 | Methods and apparatus for liquefaction of natural gas |
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Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3703068A (en) * | 1971-03-26 | 1972-11-21 | Union Carbide Corp | Control system for selective adsorption process |
US20120000242A1 (en) * | 2010-04-22 | 2012-01-05 | Baudat Ned P | Method and apparatus for storing liquefied natural gas |
-
2016
- 2016-08-05 US US15/230,357 patent/US20170153057A1/en not_active Abandoned
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3703068A (en) * | 1971-03-26 | 1972-11-21 | Union Carbide Corp | Control system for selective adsorption process |
US20120000242A1 (en) * | 2010-04-22 | 2012-01-05 | Baudat Ned P | Method and apparatus for storing liquefied natural gas |
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