EP2179235A2 - Configuration de rebouilleur d'une colonne de rejet d'azote - Google Patents

Configuration de rebouilleur d'une colonne de rejet d'azote

Info

Publication number
EP2179235A2
EP2179235A2 EP08762994A EP08762994A EP2179235A2 EP 2179235 A2 EP2179235 A2 EP 2179235A2 EP 08762994 A EP08762994 A EP 08762994A EP 08762994 A EP08762994 A EP 08762994A EP 2179235 A2 EP2179235 A2 EP 2179235A2
Authority
EP
European Patent Office
Prior art keywords
stream
lng
column
nitrogen
heat exchanger
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP08762994A
Other languages
German (de)
English (en)
Inventor
Adam Adrian Brostow
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Air Products and Chemicals Inc
Original Assignee
Air Products and Chemicals Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Air Products and Chemicals Inc filed Critical Air Products and Chemicals Inc
Publication of EP2179235A2 publication Critical patent/EP2179235A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0257—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/02—Processes or apparatus using separation by rectification in a single pressure main column system
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/40—Features relating to the provision of boil-up in the bottom of a column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/04—Recovery of liquid products
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/60—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being (a mixture of) hydrocarbons
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/30—Dynamic liquid or hydraulic expansion with extraction of work, e.g. single phase or two-phase turbine
    • 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
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • 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
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/02—Internal refrigeration with liquid vaporising loop

Definitions

  • This invention relates to a process for the separation of nitrogen from a liquid natural gas stream comprising nitrogen, methane, and possibly heavier hydrocarbons.
  • Crude natural gas is often liquefied to enable storage of larger quantities in the form of liquid natural gas (LNG).
  • LNG liquid natural gas
  • nitrogen is advantageously removed from LNG to produce a nitrogen- diminished LNG product that will meet desired product specifications.
  • One simple method for separating nitrogen from a LNG stream is to isentropically expand the crude LNG stream in a turbine and then inject the stream into a flash separator.
  • the liquid product removed from the flash separator will contain less nitrogen than the crude LNG stream, whereas the vapor product will contain a higher proportion of nitrogen.
  • a liquid stream (6; 8) is withdrawn and passed through the heat exchanger (2) to cool the feed and then reinjected into the column (5) at a level below that at which it had been withdrawn, to provide boilup to the column.
  • the passage of the withdrawn stream through the heat exchanger provides an additional equilibrium stage of separation.
  • a similar method for separating nitrogen from an LNG stream replaces the turbine driven dynamic decompression with a valve for static decompression, such that the expansion takes place isenthalpically rather than isentropically.
  • the use of the isentropic expansion in the process of the '165 patent allegedly permits greater methane recovery.
  • the sump of the column is divided by a baffle, one side of which is filled with liquid from the lowest tray of the column.
  • This bottoms liquid is withdrawn and at least partially vaporized in the heat exchanger, while condensing the vapor stream from the phase separator, and returned to the column as a reflux stream to provide boilup.
  • the liquid remaining in the reflux stream falls to the other side of the baffle in the sump.
  • This liquid reflux is then removed as a nitrogen-diminished product stream, pumped to a higher pressure, warmed and vaporized, and then dynamically expanded to reduce the temperature and pressure of the vapor product. Similar to the reboiler heat exchange of the '165 patent, the reflux of the bottoms liquid serves as an additional equilibrium stage of separation.
  • Another similar, but thermodynamically distinct method of nitrogen separation involves isentropically expanding the crude LNG stream in a turbine, cooling the expanded stream in a reboiler heat exchanger, and then injecting the cooled, expanded stream into a thermosiphon system.
  • the liquid from the bottom of the column is withdrawn, and a portion of it is withdrawn and pumped away as the LNG product.
  • a second portion is recycled through the reboiler heat exchanger where it is at least partially vaporized.
  • the partially vaporized stream is then reinjected into the column, where the vapor portion of the stream provides boilup; the liquid portion of the stream mixes with the liquid coming off the bottom tray to provide the source of the withdrawn bottoms stream.
  • a disadvantage of these prior art nitrogen separation methods is that they are each dependent upon liquid head to drive the flow of the reboiler stream.
  • This attribute has the adverse effect of limiting the flexibility of the overall process design.
  • the available head of the column will directly affect the design of the reboiler heat exchanger, wherein the pressure drop within the heat exchanger cannot be so great as to overcome the available flow.
  • This design limitation tends to result in the implementation of larger, more expensive heat exchangers that will have a lower pressure drop, thus allowing the column's head to drive the reboiler flow.
  • the large capital costs of the process equipment required to effectuate nitrogen removal can have a substantial effect on the profitability of the production of LNG.
  • the present invention provides an improved process for the denitrogenation of an LNG stream contaminated by nitrogen. This process allows for economic benefits by permitting a greater flexibility in the process design.
  • a crude LNG stream comprising between about 1% and 10% nitrogen, and the remainder methane and heavier hydrocarbons, is expanded in a means for expansion, and cooled in a heat exchanger.
  • the resultant crude LNG stream is introduced into a nitrogen rejection column, wherein the nitrogen content of the LNG is reduced as the liquid flows down the column.
  • a nitrogen-enriched vapor stream is withdrawn from the top of the column, and a nitrogen-diminished liquid stream is withdrawn from the bottom of the column.
  • the nitrogen-diminished bottoms LNG stream is pumped to a higher pressure and then divided into first and second streams, and the first stream may be collected as an LNG product if desired.
  • the second stream is reduced in pressure and then passed through the reboiler heat exchanger, thus cooling the crude LNG stream, the pressure reduction being to a level such that the second stream is at least partially vaporized in the heat exchanger.
  • the partially vaporized second stream is reinjected into the column at a level at or above the level of withdrawal of the nitrogen-diminished bottoms LNG stream and below the level of introduction of the crude LNG feed stream to provide column boilup.
  • the partially vaporized second stream is injected below the lowest separation stage, viz. lowest tray in the case of a tray column, or below the packing material in the case of a packed column.
  • the present invention provides a process for the denitrogenation of a liquid natural gas (LNG) feed stream comprising:
  • step (e) passing the bottoms stream from step (d) through a pump to increase the pressure thereof;
  • the invention provides an apparatus for the denitrogenation of a liquid natural gas (LNG) feed stream by a process of the invention, said apparatus comprising:
  • a nitrogen rejection column for separating the cooled expanded LNG feed stream into the nitrogen-enriched overhead vapor stream and the nitrogen-diminished bottoms liquid stream;
  • dividing means for dividing the bottoms stream into the first stream and the second stream
  • pressure reduction means for reducing the pressure of the second stream
  • conduit means for passing the reduced pressure second stream to the heat exchanger for at least partial vaporization therein;
  • conduit means for feeding the partially vaporized second stream into the nitrogen rejection column to provide reboil to the column.
  • the initial crude LNG stream is expanded in a dense fluid expander, which may be placed either upstream or downstream of the reboiler heat exchanger.
  • the reduction in pressure of the second stream may be accomplished through the use of a Joule- Thomson valve.
  • a valve may also be placed immediately upstream of the nitrogen rejection column, such that the crude LNG stream is throttled through the valve prior to injection into the column.
  • Figure 1 is a schematic diagram reproducing Figure 1 of the '165 patent and illustrating a process for removing nitrogen from an LNG stream in accordance with that patent.
  • Figure 2 is a schematic diagram illustrating a process for removing nitrogen from an LNG stream in accordance with one embodiment of the present invention.
  • the present invention achieves flexibility of design and process economic advantages in an LNG denitrogenation operation by using, in part, a pump to drive the reboiler stream, thus permitting a higher pressure drop within the reboiler heat exchanger.
  • This allows a higher velocity for the reboiler stream, and, consequently, higher heat transfer coefficients in the heat exchanger can be realized, permitting the use of a smaller heat exchanger.
  • achieving this flexibility without the need for additional equipment, and maintaining output levels and energy requirements involves the introduction of a small thermodynamic inefficiency.
  • the initial capital savings afforded by the present invention more than compensates for this thermodynamic inefficiency, especially given the ease and low expense with which it may be remedied.
  • nitrogen-enriched stream is used herein to mean a stream containing a higher concentration of nitrogen when compared with an initial feed stream.
  • nitrogen-diminished stream is used herein to mean a stream containing a lower concentration of nitrogen when compared with an initial feed stream.
  • below is used herein to mean at a position of lesser height, i.e., closer to the ground.
  • high-pressure LNG stream 100 typically at a pressure of about 700 psi (4.8 MPa), containing from about 1 mol% to about 10 mol% nitrogen, and the remainder methane and possibly heavier hydrocarbons, is expanded via means 102 for expanding the LNG stream to produce lower-pressure LNG stream 104.
  • the expansion is preferably performed isentropically, and the means for expanding the LNG stream is preferably a dense fluid expander (also known as a hydraulic turbine), but may also be a valve or other known means for expanding a fluid.
  • Lower-pressure LNG stream 104 is cooled in reboiler heat exchanger 106 to produce cooled, expanded LNG stream 108.
  • Reboiler heat- exchanger 106 is preferably a plate-fin heat exchanger, but may be a shell-and-tube design, or any other known means for bringing two fluid streams into a heat exchange relation with each other, without mixing the fluids.
  • Nitrogen rejection column 150 is preferably a tray column, but may be a packed column or any other mass transfer device suitable for fractionation.
  • a nitrogen-enriched vapor stream 130 is withdrawn from the top of column 150. This stream will typically contain more than about 30% N 2 and less than about 70% methane.
  • Nitrogen-diminished liquid stream 110 is withdrawn from the bottom of column 150 and pumped through pump 112 to a desired pressure. After bottoms liquid stream 110 is pumped, it is split into a first stream 114 and a second stream 116. Stream 114 may be recovered as a product LNG stream. Stream 116 is substantially isenthalpically expanded through Joule-Thomson valve 117 Joule-Thomson valve, to produce low-pressure reboiler stream 118. Valve 117 may be located at any position between the point of separation of streams 114 and 116 and the reboiler heat exchanger 106.
  • Low-pressure reboiler stream 118 is at least partially vaporized in reboiler heat exchanger 106 to produce partially vaporized reboiler stream 120, which is then injected into the bottom of column 150, below the lowest tray in the case of a tray column, or below the packing material in the case of a packed column, to provide boilup.
  • the means for expanding the LNG stream 102 may be placed downstream of reboiler heat exchanger 106. In this manner, high- pressure stream 100 is cooled in reboiler heat exchanger 106 prior to undergoing expansion in the means for expanding the LNG stream 102.
  • valve 109 is optional, and, in the alternative, cooled LNG stream 108 can be directly injected into nitrogen rejection column 150.
  • a particularly preferred embodiment is herein provided wherein a crude LNG stream 100 is substantially isentropically expanded in a dense fluid expander 102 and cooled in a reboiler heat exchanger 106. This cooled, expanded LNG stream
  • a nitrogen rejection column 150 is substantially isenthalpically expanded through valve 109 and injected into a nitrogen rejection column 150.
  • rising vapor strips the nitrogen from the falling liquid, and a nitrogen-enriched stream 130 is withdrawn from the top of the column.
  • a nitrogen-diminished liquid stream 110 is withdrawn from the bottom of the column and its pressure is increased by passage through a pump 112. After pumping, the liquid stream is divided into a first stream 114 and a second stream 116.
  • the second stream 116 is reduced in pressure by passage through a valve 117 to a pressure that allows low-pressure reboiler stream 118 to at least partially vaporize during its subsequent passage through the reboiler heat exchanger 106.
  • the reboiler stream 120 is reinjected into the nitrogen rejection column 150 to provide boilup.
  • the liquid portion of the reboiler stream mixes with the liquid from the lowest column stage upon reinjection such that the nitrogen-diminished liquid stream 110 is not exclusively the liquid from the bottom stage of the rejection column 150, or from the reboiler 106, but rather a mixture of both.
  • this can easily and cheaply be compensated for by the addition of a stage or stages to the nitrogen rejection column 150.
  • the flow through the reboiler heat exchanger 106 is driven by a pump 112 that would already be available to pump the LNG product, first stream 114.
  • the reboiler heat exchanger 106 can be designed for a broad range of pressure drops based on considerations such as capital cost, and the appropriate pressure of the reboiler stream 118 can be attained by adjusting valve 117 upstream of the reboiler heat exchanger 106.
  • the flow rate of the second stream 116 can be any amount up to the total flow of the nitrogen-diminished liquid stream 110, but is preferably less than about 20% of the flow rate of the first stream 114, and may be easily optimized for the particular process. This is in contrast with the process of the '165 patent, which requires 100% of the liquid flow off of a tray to be directed through the reboiler.
  • the smaller flow rate of the reboiler stream compared with the prior art allows the reboiler heat exchanger 106 to be reduced in size.
  • the present invention has the additional advantage of eliminating the nozzle required for the withdrawal of the reboiler liquid stream from the column, since bottoms liquid that would be withdrawn anyway as LNG product is employed for column reboil.
  • the present invention provides a significant improvement in the adaptability and flexibility of a LNG denitrogenation process through the implementation of a hydraulically different process from those of the prior art.
  • a pump 112 to drive the reboiler heat exchanger 106, rather than relying on the column head, and including the valve 117 to control mass flow, the process may be designed to optimally perform in conjunction with a chosen reboiler heat exchanger 106 design. This flexibility can lead to a smaller capital expense at the remediable cost of a minor thermodynamic loss.
  • Cooled, expanded stream 108 is throttled through valve 109 and introduced into a denitrogenation column 150 comprising 6 trays, at a pressure of 18 psi (124 kPa).
  • An overhead vapor stream 130 is withdrawn from the top of the column 150 at a flow rate of 8,123 Ibmol/h (3,685 kgmol/h), and contains 31.06% N 2 , 68.94% methane, and trace amounts of heavier hydrocarbons, at a pressure of 18 psi (124 kPa) and a temperature of -261.9 0 F (-163.28 0 C).
  • Bottoms stream 110 is withdrawn from the column 150 at a flowrate of 136,071 Ibmol/h (61720 kgmol/h), a pressure of 19.45 psi
  • Bottoms stream 110 is pumped to a pressure of 75 psi (517 kPa) and divided into a first stream 114 and a second stream 116.
  • the first stream 114 at a flow rate of 117,327 Ibmol/h (53,219 kgmol/h), a pressure of 75 psi (517 kPa), a temperature of -256.6 0 F
  • the second stream 116 at a flow rate of 18,744 Ibmol/h (8,502 kgmol/h) is throttled through valve 117 to a pressure of 19.74 psi (136.17 kPa) to produce low pressure reboiler stream 118, which is then introduced to reboiler heat exchanger 106 at a temperature of -256.4 0 F (-160.22 0 C), where it is partially vaporized to produce vaporized reboiler stream 120.
  • Vaporized reboiler stream 120 which is at a temperature of -252.7 0 F (-158.17 0 C), a pressure of 19.45 psi (134.17 kPa), and has a vapor fraction of 23.7%, is injected into the bottom of column 150 to provide boilup. This process requires approximately 229 MW of power.
  • This cooled, expanded stream is throttled through valve 3 and introduced into denitrogenation column 5 comprising 6 trays, at a pressure of 18 psi (124 kPa).
  • An overhead vapor stream 10 is withdrawn from the top of the column 5 at a flow rate of 8,122 Ibmol/h (3684 kgmol/h), and contains 31.17% N 2 , 68.83% methane, and trace amounts of heavier hydrocarbons, at a pressure of 18 psi (124 kPa) and a temperature of -261.9 0 F (-163.28 0 C).
  • Bottoms stream 11 is withdrawn from the column 5 at a fiowrate of 117,329 Ibmol/h (53,220 kgmol/h), a pressure of 19.45 psi (134.1 kPa), a temperature of -256.8 0 F (-160.44 0 C), and contains 1.01%
  • First LNG fraction 6 is withdrawn from the lowest tray of the column at a flow rate of 121 ,047 Ibmol/h (54,906 kgmol/h), a temperature of -259.7 0 F (-162.06 0 C), a pressure of 19.74 psi (136.17 kPa), and contains 1.56% N 2 , 96.81% methane, 1.14% C 2 hydrocarbons, and 0.49% heavier hydrocarbons.
  • This first LNG fraction 6 is passed through indirect heat exchanger 2 to produce stream 7, which is at a temperature of -256.8 0 F (-160.44 0 C), a pressure of 19.45 psi (134.1 kPa), and has a vapor fraction of 3.1 %.
  • Stream 7 is returned to column 5 under the lowest tray to provide boilup. This process also requires approximately 229 MW of power.
  • Table 1 sets forth data of corresponding streams of these two processes in order to more clearly illustrate the comparison.
  • the respective feed streams, 104 and 22, and the respective product streams, 114 and 11, and 130 and 10, are substantially identical with respect to all relevant properties. This equivalency of feed streams and product streams enables a valid comparison of the two processes.
  • the reboiler stream 118 of the current process is at a flow rate of 18,744 Ibmol/h (8,502 kgmol/h), which is only 15.5% of the flow rate of the reboiler stream 6 of the '165 patent process, 121 ,047 Ibmoi/h (54,906 kgmol/h).
  • This difference is attributable to the fact that, while the '165 patent process requires that the entire liquid flow off of a column tray be recycled through the reboiler heat exchanger, the current process optimizes the amount of flow necessary to achieve the desired separation, and therefore only recycles the amount of bottoms liquid necessary to produce the required product.
  • valve 117 can be adjusted to compensate for a greater pressure drop in the heat exchanger. This additional flexibility may be reflected not only in the initial design of the heat exchanger, but also may be advantageously employed to compensate for unexpected process conditions.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)

Abstract

Selon l'invention, un courant de gaz naturel liquéfié brut (108), dilaté (102) et refroidi (106) est séparé dans une colonne (150) de rejet d'azote en un courant de vapeur de tête enrichi en azote (130) et un courant de liquide de résidu à teneur diminuée en azote (110). Le courant de résidu (110) est pompé (112) à une pression supérieure, divisé en des premier et second courants (114 & 116), puis le second courant est réduit en pression et au moins partiellement vaporisé (118) par échange de chaleur (106) contre le courant (104) d'alimentation en GNL brut pour refroidir ledit courant d'alimentation et obtenir (120) un état d'ébullition à la colonne de rejet d'azote (150).
EP08762994A 2007-06-19 2008-06-16 Configuration de rebouilleur d'une colonne de rejet d'azote Withdrawn EP2179235A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US11/764,975 US20080314079A1 (en) 2007-06-19 2007-06-19 Nitrogen Rejection Column Reboiler Configuration
PCT/IB2008/001742 WO2008155653A2 (fr) 2007-06-19 2008-06-16 Configuration de rebouilleur d'une colonne de rejet d'azote

Publications (1)

Publication Number Publication Date
EP2179235A2 true EP2179235A2 (fr) 2010-04-28

Family

ID=40135079

Family Applications (1)

Application Number Title Priority Date Filing Date
EP08762994A Withdrawn EP2179235A2 (fr) 2007-06-19 2008-06-16 Configuration de rebouilleur d'une colonne de rejet d'azote

Country Status (12)

Country Link
US (1) US20080314079A1 (fr)
EP (1) EP2179235A2 (fr)
JP (1) JP2011513503A (fr)
KR (1) KR20100021443A (fr)
CN (1) CN102084199A (fr)
AU (1) AU2008264885A1 (fr)
BR (1) BRPI0812568A2 (fr)
CA (1) CA2687886A1 (fr)
PE (1) PE20090450A1 (fr)
RU (1) RU2010101417A (fr)
TW (1) TW200902703A (fr)
WO (1) WO2008155653A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108369061A (zh) * 2015-12-14 2018-08-03 埃克森美孚上游研究公司 使用液化氮从液化天然气中分离氮的方法和系统

Families Citing this family (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090139263A1 (en) * 2007-12-04 2009-06-04 Air Products And Chemicals, Inc. Thermosyphon reboiler for the denitrogenation of liquid natural gas
US8522574B2 (en) * 2008-12-31 2013-09-03 Kellogg Brown & Root Llc Method for nitrogen rejection and or helium recovery in an LNG liquefaction plant
CN102994184B (zh) * 2012-12-03 2013-10-30 中国石油集团工程设计有限责任公司 一种液化天然气联产液氮的装置及方法
KR101550618B1 (ko) 2014-01-14 2015-09-07 현대자동차 주식회사 리보일링 장치 및 이를 구비한 재생탑
FR3075658B1 (fr) * 2017-12-21 2022-01-28 Air Liquide Procede de limitation de la concentration d'oxygene contenu dans un courant de biomethane
US11221176B2 (en) * 2018-08-14 2022-01-11 Air Products And Chemicals, Inc. Natural gas liquefaction with integrated nitrogen removal
US20200378682A1 (en) * 2019-05-29 2020-12-03 Uop Llc Use of dense fluid expanders in cryogenic natural gas liquids recovery

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB968019A (en) * 1963-08-19 1964-08-26 Alexander Harmens Cold separation of gas mixtures
GB1288762A (fr) * 1968-09-16 1972-09-13
DE2154965A1 (de) * 1971-06-24 1973-05-10 Linde Ag Verfahren zur zerlegung von gasgemischen
DE2202206A1 (de) * 1972-01-18 1973-07-26 Messer Griesheim Gmbh Verfahren zur zerlegung von gasgemischen durch zweistufige rektifikation
US4451275A (en) * 1982-05-27 1984-05-29 Air Products And Chemicals, Inc. Nitrogen rejection from natural gas with CO2 and variable N2 content
AU572890B2 (en) * 1983-09-20 1988-05-19 Costain Petrocarbon Ltd. Separation of hydrocarbon mixtures
US4592767A (en) * 1985-05-29 1986-06-03 Union Carbide Corporation Process for separating methane and nitrogen
US4732598A (en) * 1986-11-10 1988-03-22 Air Products And Chemicals, Inc. Dephlegmator process for nitrogen rejection from natural gas
US5041149A (en) * 1990-10-18 1991-08-20 Union Carbide Industrial Gases Technology Corporation Separation of nitrogen and methane with residue turboexpansion
FR2682964B1 (fr) * 1991-10-23 1994-08-05 Elf Aquitaine Procede de deazotation d'un melange liquefie d'hydrocarbures consistant principalement en methane.
US5339641A (en) * 1993-07-07 1994-08-23 Praxair Technology, Inc. Cryogenic liquid nitrogen production system
RU2141611C1 (ru) * 1995-10-05 1999-11-20 Би Эйч Пи Петролеум ПТИ, Лтд. Способ сжижения
US5927103A (en) * 1998-06-17 1999-07-27 Praxair Technology, Inc. Carbon dioxide production system with integral vent gas condenser
MY117066A (en) * 1998-10-22 2004-04-30 Exxon Production Research Co Process for removing a volatile component from natural gas
GB0111961D0 (en) * 2001-05-16 2001-07-04 Boc Group Plc Nitrogen rejection method
US6393866B1 (en) * 2001-05-22 2002-05-28 Praxair Technology, Inc. Cryogenic condensation and vaporization system
FR2885679A1 (fr) * 2005-05-10 2006-11-17 Air Liquide Procede et installation de separation de gaz naturel liquefie

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2008155653A2 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108369061A (zh) * 2015-12-14 2018-08-03 埃克森美孚上游研究公司 使用液化氮从液化天然气中分离氮的方法和系统
CN108369061B (zh) * 2015-12-14 2020-05-22 埃克森美孚上游研究公司 使用液化氮从液化天然气中分离氮的方法和系统

Also Published As

Publication number Publication date
TW200902703A (en) 2009-01-16
WO2008155653A2 (fr) 2008-12-24
JP2011513503A (ja) 2011-04-28
AU2008264885A1 (en) 2008-12-24
CA2687886A1 (fr) 2008-12-24
WO2008155653A3 (fr) 2011-04-07
RU2010101417A (ru) 2011-07-27
BRPI0812568A2 (pt) 2015-02-18
PE20090450A1 (es) 2009-04-27
US20080314079A1 (en) 2008-12-25
CN102084199A (zh) 2011-06-01
KR20100021443A (ko) 2010-02-24

Similar Documents

Publication Publication Date Title
WO2008155653A2 (fr) Configuration de rebouilleur d'une colonne de rejet d'azote
AU2005236007B2 (en) Hydrocarbon gas processing for rich gas streams
JP4607990B2 (ja) 凝縮天然ガスからの窒素除去装置
CN100588702C (zh) 同时生产可液化天然气和天然气液体的馏分的方法和装置
AU2002219300B2 (en) Method and installation for separating a gas mixture containing methane by distillation
CN101108977B (zh) 在液化天然气制备中的一体化ngl回收
EP3168558B1 (fr) Procédé et appareil pour la liquéfaction de gaz naturel
CN101824344B (zh) 氮去除和等压开放式制冷的天然气液回收
US8959952B2 (en) Method for separating a mixture of carbon monoxide, methane, hydrogen and optionally nitrogen by cryogenic distillation
CN100547326C (zh) 精制天然气、富c3+烃馏分及富乙烷流束的生产方法和设备
WO1997046503A1 (fr) Enlevement de dioxyde de carbone, d'ethane et de constituants plus lourds a partir de gaz naturel
CN1129766C (zh) 分离气体混合物的方法和装置
US20120324943A1 (en) Two Step Nitrogen and Methane Separation Process
EP2215415A2 (fr) Rebouilleur à thermosiphon pour la dénitrogénation de gaz naturel liquide
EP0742415A2 (fr) Procédé pour l'élimination d'azote de gaz naturel liquéfié
US20230050081A1 (en) Process for Separating Hydrogen from an Olefin Hydrocarbon Effluent Vapor Stream
WO2017015379A1 (fr) Système et procédé pour la séparation de grandes variations dans du méthane et de l'azote
CN118064196A (zh) 降低马力要求的甲烷和氮气分离系统和方法
US20230160633A1 (en) Process for Separating Hydrogen from an Olefin Hydrocarbon Effluent Vapor Stream
US20160245584A1 (en) Method for denitrogenation of natural gas with or without helium recovery
CA2441136A1 (fr) Meilleure separation thermodynamique d'elements plus lourds du gaz naturel

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20091202

AK Designated contracting states

Kind code of ref document: A2

Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

AX Request for extension of the european patent

Extension state: AL BA MK RS

R17D Deferred search report published (corrected)

Effective date: 20110407

18W Application withdrawn

Effective date: 20110519

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION HAS BEEN WITHDRAWN

R18W Application withdrawn (corrected)

Effective date: 20110518