EP0725256A1 - Verfahren zur Entfernung von Stickstoff aus Erdgas - Google Patents

Verfahren zur Entfernung von Stickstoff aus Erdgas Download PDF

Info

Publication number
EP0725256A1
EP0725256A1 EP96300725A EP96300725A EP0725256A1 EP 0725256 A1 EP0725256 A1 EP 0725256A1 EP 96300725 A EP96300725 A EP 96300725A EP 96300725 A EP96300725 A EP 96300725A EP 0725256 A1 EP0725256 A1 EP 0725256A1
Authority
EP
European Patent Office
Prior art keywords
stream
nitrogen
distillation column
rich
vapour
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.)
Granted
Application number
EP96300725A
Other languages
English (en)
French (fr)
Other versions
EP0725256B1 (de
Inventor
Brian A. McNeill
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 EP0725256A1 publication Critical patent/EP0725256A1/de
Application granted granted Critical
Publication of EP0725256B1 publication Critical patent/EP0725256B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • F25J3/028—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 noble gases
    • F25J3/029—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 noble gases of helium
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the feed stream
    • F25J3/0209—Natural gas or substitute natural gas
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0233—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream separation of CnHm with 1 carbon atom or more
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0228—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream characterised by the separated product stream
    • F25J3/0257—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
    • F25J2200/50—Processes or apparatus using separation by rectification using multiple (re-)boiler-condensers at different heights of the 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
    • F25J2200/76—Refluxing the column with condensed overhead gas being cycled in a quasi-closed loop refrigeration cycle
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/06—Splitting of the feed stream, e.g. for treating or cooling in different ways
    • 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
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being 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
    • 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
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/04—Internal refrigeration with work-producing gas expansion loop
    • 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
    • F25J2270/42—Quasi-closed internal or closed external nitrogen refrigeration cycle

Definitions

  • the present invention relates to a cryogenic process for the removal of nitrogen from feed gas comprising nitrogen and hydrocarbons.
  • the increasing use of natural gas as a fuel has resulted in a need to remove nitrogen from some natural gas sources, in order to meet Wobbe Index and calorific value specifications, particularly where the gas is delivered into a country's gas transmission system.
  • the nitrogen may either be naturally occurring or resulting from nitrogen injection into oil fields for enhanced recovery.
  • a particular problem is to design a process for efficient removal of nitrogen from natural gas feed at high pressure (75 to 130 bar absolute; 7.5 to 13 MPa), with relatively small concentrations of nitrogen (5 to 15 mol%), and to produce sales gas at a pressure similar to the feed gas pressure.
  • a further problem is that, as gas reservoir pressure decays to below the required sales gas pressure (e.g., about 75 bar absolute; 7.5 MPa in the case of the United Kingdom's National Transmission System), feed gas compression needs to be added. This is a relatively expensive investment because it is not utilized fully throughout the life of the nitrogen removal unit (NRU).
  • NRU nitrogen removal unit
  • an object of the present invention is to provide an improved process to remove nitrogen from natural gas feed with low nitrogen content (about 5 to 15 mol%) and at high pressure (75 to 130 bar absolute; 7.5 to 13 MPa). It is a further object of this invention to provide a process for removal of nitrogen from natural gas feed, which is sufficiently flexible to operate at lower feed pressure (25 to 75 bar absolute; 2.5 to 7.5 MPa) while still producing sales gas at higher pressure (about 75 bar absolute; 7.5 MPa), without the need for feed gas compression.
  • Nitrogen removal from natural gas is usually most economically effected by cryogenic distillation. Numerous cycles have been developed, many based on the concept of double distillation columns as used in air separation. One problem associated with double column cycles is that, at feed nitrogen concentrations less than 25 mol%, the quantity of reflux liquid that can be generated is insufficient to achieve an economic recovery of methane. Another problem is that relatively low concentrations of carbon dioxide and hydrocarbons, such as benzene, hexane and heavier components, would freeze at the cryogenic temperatures associated with the lower pressure column.
  • GB-B-2208699 describes an improved process that is less energy intensive at low levels of feed nitrogen concentration, in which the separation is effected in two columns with integrated condensation of overhead first column vapour and second column reboil. While this process overcomes the problems mentioned above, it is relatively complicated and expensive.
  • US-A-4415345 also EP-A-0090469) describes a process employing a nitrogen heat pump cycle to generate liquid reflux, which is compatible with both single column and double column arrangements.
  • this cycle produces methane product at a lower pressure than the natural gas feed and will generally require product gas compression in addition to the nitrogen heat pump compressor. It also limits the column to a low operating pressure of from 15 to 125 psia; (100 to 865 kPa), with heat pump nitrogen at a pressure of 50 to 470 psia (345 to 3,250 kPa), i.e. below the critical pressure.
  • the column pressure is, therefore, dictated by the nitrogen pressure to allow sufficient temperature difference to condense the nitrogen against boiling methane in the column reboiler. This low column operating pressure increases power consumption for product compression.
  • US-A-4501600 discloses a cryogenic rectification process for the separation of nitrogen from natural gas in which a natural gas feed is introduced into a rectification column operating at a pressure of 200 to 450 psia (1.4 to 3.1 MPa) where it is separated into a nitrogen-rich overhead vapour and a methane-rich bottoms liquid.
  • the overhead vapour is partially condensed by indirect heat exchange with vaporizing heat pump fluid and the condensed portion of the overhead vapour is returned to the column as reflux.
  • the heat pump fluid is specified to comprise 0.5 to 60 mole percent nitrogen and 99.5 to 40 mole percent methane and flows in an external closed loop heat pump system.
  • an intermediate vapour stream also is condensed against the heat pump fluid and returned to the rectification column as additional reflux.
  • US-A-4662919 discloses a process for separating nitrogen from a pressurized feed containing natural gas and nitrogen in a single distillation column with two side intermediate condensers to form pressurized product streams of nitrogen and natural gas.
  • the pressurized feed is cooled and separated into separate multiple feeds to the column where the cooled feeds are distilled to form a pressurized nitrogen-rich overhead vapour and a pressurized hydrocarbon-rich bottoms liquid.
  • the overhead vapour is condensed by heat exchange with a first closed loop refrigerant to provide upper reflux to the column; an upper intermediate vapour from the column is condensed in an upper side condenser by heat exchange with the unexpanded overhead vapour to provide an upper intermediate reflux to the column; and a lower intermediate vapour from the column is condensed in a lower side condenser by heat exchange with a second closed loop refrigerant and by heat exchange with the unexpanded overhead vapour to provide a lower intermediate reflux to the column.
  • the upper intermediate vapour is withdrawn from the column between the overhead vapour condenser and the lower side condenser and the lower intermediate vapour is withdrawn from the column between the upper side condenser and the highest feed point to the column.
  • the first and second closed loop refrigerants are respective portions of an external closed loop methane heat pump system and the distillation column operates at a pressure of 300 to 400 psia (2 to 2.8 MPa). It is stated that since the fractionation above 400 psia (2.8 MPa) approaches the critical pressure of nitrogen, higher pressures are impractical.
  • US-A-4504295 discloses a process for the recovery of methane and nitrogen from a natural gas stream in which a nitrogen rejection stage including a heat pump driven distillation column is integrated with a natural gas liquid stage.
  • the feed stream is separated into an ethane-rich fraction and nitrogen-rich fraction.
  • the nitrogen-rich fraction is introduced into a distillation column driven with a closed loop heat pump refrigerant which condenses an overhead reflux stream, condenses an intermediate reflux stream and vaporizes a reboil stream to the distillation column.
  • the ethane-rich fraction is distilled in a second column to provide a methane-rich overhead.
  • the distillation column operates at 300 to 400 psia (2 to 2.8 MPa) and the heat pump refrigerant is methane.
  • the present invention provides a cryogenic process for the removal of nitrogen from a natural gas feed stream comprising nitrogen and hydrocarbons primarily having a carbon content between 1 and 8 carbon atoms comprising:
  • the invention also provides an apparatus for the cryogenic removal of nitrogen from a natural gas feed stream by the process of the invention, the apparatus comprising:
  • One or more intermediate vapour streams can be partially condensed in step (iii) of the process of the invention but it is preferred that a lower intermediate vapour stream is withdrawn at or above the location of the feed point of the natural gas feed stream and returned as reflux above said withdrawal point, and an upper intermediate vapour stream is withdrawn at or above said lower reflux feed point and returned as reflux above the withdrawal point of the upper intermediate vapour stream.
  • the methane-rich bottoms liquid is pumped and then vaporized to increase its pressure before recovery as the methane-rich product.
  • the distillation column is reboiled by heat exchange with both the natural gas feed stream and the recycle nitrogen-rich heat pump stream.
  • the present invention relates to a cryogenic process for the removal of nitrogen from a natural gas feed stream comprising nitrogen and hydrocarbons primarily having a carbon content between 1 and 8 carbon atoms comprising:
  • the natural gas feed stream is divided into first and second portions; said first portion is reduced in pressure and fed to an intermediate location of the distillation column; and said second portion is reduced in pressure, partially vaporized and then fed to the distillation column at a location below the feed for said first portion.
  • a portion of the warmed nitrogen-rich overhead vapour suitably is expanded and then further warmed to recover refrigeration.
  • the methane-rich bottoms liquid usually will be subcooled prior to pumping and suitably this subcooling is by heat exchange with a reduced pressure portion of the feed stream.
  • the recycle nitrogen-rich heat pump stream conveniently is both compressed and, after cooling, subsequently expanded in a compander.
  • the pressure of at least part of the natural gas feed stream is reduced, prior to feeding to the distillation column, with a dense fluid expander.
  • the distillation column can have an intermediate reboiler/condenser located below the feed point of the natural gas feed stream.
  • Figure 1 is a schematic diagram of the process of the present invention.
  • a natural gas feed in line 101 which has been treated to reduce to acceptable concentrations freezing components, such as water and carbon dioxide, is cooled and at least partially condensed in main heat exchanger 1.
  • the natural gas feed will generally contain 5 to 15 mol% nitrogen with the balance being natural gas and impurities and will be at a pressure of 25 to 130 bar absolute (2.5 to 13 MPa), preferably 60 to 80 bar absolute (6 to 8 MPa).
  • the cooled and at least partially condensed natural gas feed is then further cooled and condensed (if not totally condensed in main heat exchanger 1) in reboiler 2, and split into two portions in lines 201 and 202.
  • the major portion in line 202 is subcooled in subcooler 3 before being introduced via line 102 to distillation column 11 through valve 41.
  • the smaller portion in line 201 is reduced in pressure across valve 42 and partially vaporized in subcooler 5 before also being introduced to distillation column 11.
  • Distillation column 11 operates at a pressure from 10 to 30 bar absolute (1 to 3 MPa), preferably between 15 and 22 bar absolute (1.5 and 2.2 MPa), and separates the natural gas feeds into a methane-rich bottoms liquid stream 103 and a nitrogen-rich overhead vapour stream 105.
  • the nitrogen-rich overhead stream 105 typically contains 2 mol% methane, and the methane-rich bottoms stream 103 has a typical nitrogen concentration of 0.5 mol%, which is generally lower than the required nitrogen content of natural gas that is delivered, for example, to the United Kingdom's National Transmission System (NTS), where concentrations of 4 to 5 mol% are acceptable in gas with parts per million concentrations of carbon dioxide.
  • NTS National Transmission System
  • Part of the reboil duty for column 11 is provided by heat exchange with the natural gas feed cooling in reboiler 2. The remainder is provided by heat exchange with a recycle, nitrogen-rich heat pump stream also cooling in reboiler 2.
  • the recycle, nitrogen-rich heat pump stream in line 110 is cooled in main heat exchanger 1 and reboiler 2 at a pressure of 35 to 130 bar absolute (3.5 to 13 MPa), preferably between 60 and 80 bar absolute (6 and 8 MPa).
  • the cooled, recycle, nitrogen-rich heat pump stream in line 111 is then expanded in the expansion wheel of compander 32 and introduced into the top of distillation column 11.
  • the expander outlet stream contains 4 to 5% by mass of liquid, and this is used to provide reflux for the top section of distillation column 11.
  • Condenser 4 provides the bulk of the reflux liquid for distillation column 11 by condensing vapour side streams withdrawn from the column.
  • the lower side stream in line 112 is withdrawn at or above the feed entry location (line 102) and returned as reflux liquid in line 113 which is several equilibrium stages above the withdrawal point (line 112).
  • the upper side stream in line 114 is withdrawn at or above the lower reflux feed point (line 113) and returned in line 115 several equilibrium stages above this withdrawal point.
  • This reflux philosophy is more efficient than a process that provides all of the column reflux liquid at the top of the column, because the majority of the refrigeration required to condense the reflux is provided at the warmer condensing temperatures of the side streams.
  • a portion of the nitrogen-rich overhead vapour in line 106 is expanded in expander 33, providing additional refrigeration to condenser 4 and subcooler 3. This expanded portion is then warmed in main heat exchanger 1 and vented via line 107 to atmosphere.
  • Environmental constraints will generally limit the methane content in vented nitrogen to 2 mol% maximum.
  • the process is capable of achieving much lower methane content, if required, by increasing the recycle nitrogen flow in line 110.
  • Some of the nitrogen-rich vent stream may be used as utility nitrogen for purposes such as cold box purge and adsorber regeneration.
  • the remaining nitrogen-rich overhead vapour is warmed in main heat exchanger 1, compressed in compressor 31, passed via line 109 to the compressor wheel of compander 32 and cooled in cooler 6 to form the recycle, nitrogen-rich stream to main heat exchanger 1 in line 110.
  • Methane-rich bottoms liquid from column 11 is subcooled in subcooler 5 before being increased in pressure by pump 21.
  • Subcooler 5 minimizes the elevation which distillation column 11 is required to be above pump 21 in order to provide the necessary net positive suction head (NPSH) at the pump suction, particularly, if there is a large turndown requirement where heat leak into the pump suction piping could cause cavitation at turndown.
  • the pumped liquid is then vaporized in main heat exchanger 1 to be delivered as sales gas product at a pressure of 25 to 130 bar absolute (2.5 to 13 MPa), preferably 60 to 80 bar absolute (6 to 8 MPa).
  • the process achieves a very high methane recovery, typically about 99.8 mol%, because the methane content in the vent nitrogen can be reduced to less than 2 mol%.
  • Table 1 summarizes a mass balance for a typical application of this invention.
  • the number of side streams that are condensed in condenser 4 could be increased to three or more if the resulting reduction in power consumption warranted the additional complexity.
  • the system could be simplified by condensing only one side stream.
  • vent nitrogen can be produced at a higher pressure and used as a by-product by increasing expander 33 outlet pressure or by the removal of a nitrogen containing stream prior to the inlet to compressor 31, prior to the inlet to the compressor wheel of compander 32, or from downstream of cooler 6. This may result in the elimination of expander 33 from the process. It is possible to eliminate expander 33 in any event by increasing the refrigeration produced by compander 32, although this is less efficient.
  • Expander 33 could be moved to provide refrigeration at a warmer part of the process, e.g., around exchanger 1. This could be beneficial where the feed pressure was much lower than the required sales gas product pressure.
  • vent nitrogen In addition to the vent nitrogen, all or some of the recycle heat pump nitrogen could be expanded in expander 33. This would reduce the flowrate of the recycle heat pump nitrogen, but would also reduce the inlet pressure to compressor 31 and, thus, possibly require two (2) differing pressure feeds to the compressor.
  • Subcooler 5 could be eliminated and the required pump NPSH developed by increasing the elevation difference between the column sump and the pump suction.
  • Part of the feed could be subcooled to a lower temperature in subcooler 3, rather than subcooling all of the feed, that is expanded across valve 41, to a warmer temperature. This colder feed could then be introduced to column 11 a few stages higher than the remaining feed from upstream of subcooler 3.
  • the column system could be modified to include an intermediate reboiler between the bottom of the column and the main feed stage. This may be appropriate for higher feed nitrogen concentrations.
  • the position of compander 32 could be changed so that recycle nitrogen was compressed in the compressor wheel of the compander before being compressed in compressor 31. This would be determined by the optimum machinery configuration.
  • Liquid methane from the bottom of column 11 could be further processed to recover a natural gas liquids product.
  • the process could be modified to recover a helium-rich stream from the overhead vapour from column 11, where there was sufficient helium in the natural gas feed to make this economically attractive.
  • the process could be operated with a much higher methane content in the vent nitrogen for possible use as a fuel stream with a consequent reduction in power consumption.
  • the exemplified embodiment of the invention provides a process cycle with only slightly higher power consumption than the efficient cycle described in GB-B-2,208,699, but which is much simpler and has a significantly lower capital cost.
  • the refrigeration provided by the expansion wheel of compander 32 and expander 33 is sufficient to compensate for pump work, heat leak and temperature difference at the warm end of main heat exchanger 1 and enables the sales gas product to be delivered at a similar pressure to the feed with no need for any product compression.
  • the expansion work of the recycle nitrogen is efficiently recovered in the compressor wheel of compander 32.
  • the sales gas can still be produced at the required pressure simply by increasing the refrigeration provided by the expansion wheel of compander 32 beyond what is required for the column reflux liquid. This compensates for the reduced Joule-Thomson refrigeration that is available from the lower pressure feed.
  • sales gas can be produced at, for example, 79 bar absolute (7.9 MPa) with the feed gas pressure as low as 25 bar absolute (2.5 MPa).
  • Operation of the NRU is less efficient at feed gas pressures much below the required sales gas pressure, and capacity will be reduced because all of the feed gas will need to be processed in the NRU because there can be no bypass.
  • the size of compander 32 will limit production. However, this gives the plant operator the choice of whether or not to invest in feed gas compression and certainly postpones the date at which it becomes economically viable to purchase or lease this compression system.
  • the problem of freezing carbon dioxide and heavy hydrocarbons is mitigated by the single column process, operating at high pressure, because the freezing components are recovered in the bottom section of the column where the temperature is higher.
  • the closest approach to freezing generally occurs at the feed inlet to the column, downstream of valve 41.
  • the process is tolerant to significantly higher concentrations of carbon dioxide and heavy hydrocarbons than a double column process.
EP19960300725 1995-02-03 1996-02-01 Verfahren zur Entfernung von Stickstoff aus Erdgas Expired - Lifetime EP0725256B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9502126 1995-02-03
GB9502126A GB2297825A (en) 1995-02-03 1995-02-03 Process to remove nitrogen from natural gas

Publications (2)

Publication Number Publication Date
EP0725256A1 true EP0725256A1 (de) 1996-08-07
EP0725256B1 EP0725256B1 (de) 1999-06-09

Family

ID=10769044

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19960300725 Expired - Lifetime EP0725256B1 (de) 1995-02-03 1996-02-01 Verfahren zur Entfernung von Stickstoff aus Erdgas

Country Status (4)

Country Link
EP (1) EP0725256B1 (de)
DE (1) DE69602771T2 (de)
GB (1) GB2297825A (de)
NO (1) NO308628B1 (de)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1131144A2 (de) * 1998-10-22 2001-09-12 Exxonmobil Upstream Research Company Verfahren zur trennung eines einspeisungsstroms mit mehreren komponenten durch destillation
EP1384966A2 (de) * 2002-07-16 2004-01-28 The BOC Group plc Verfahren und Vorrichtung zur Stickstofftrennung
EP1396694A1 (de) * 2002-09-06 2004-03-10 The BOC Group plc Verfahren und Vorrichtung zur Stickstofftrennung
WO2004104143A1 (en) * 2003-05-22 2004-12-02 Air Products And Chemicals, Inc. Nitrogen rejection from condensed natural gas
US7520143B2 (en) 2005-04-22 2009-04-21 Air Products And Chemicals, Inc. Dual stage nitrogen rejection from liquefied natural gas
FR2936864A1 (fr) * 2008-10-07 2010-04-09 Technip France Procede de production de courants d'azote liquide et gazeux, d'un courant gazeux riche en helium et d'un courant d'hydrocarbures deazote et installation associee.
WO2010051971A2 (de) * 2008-11-06 2010-05-14 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2010051970A2 (de) * 2008-11-06 2010-05-14 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2011064605A3 (en) * 2009-11-30 2013-04-04 Costain Oil, Gas & Process Limited Process and apparatus for separation of nitrogen from lng
US20170343257A1 (en) * 2014-12-26 2017-11-30 Mitsubishi Heavy Industries Compressor Corporation Gas recovery system for compressor, compressor system, and refrigeration cycle system
WO2020219299A1 (en) * 2019-04-23 2020-10-29 Chart Energy & Chemicals, Inc. Single column nitrogen rejection unit with side draw heat pump reflux system and method

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9802231D0 (en) * 1998-02-02 1998-04-01 Air Prod & Chem Separation of carbon monoxide from nitrogen-contaminated gaseous mixtures also containing hydrogen
DE10121339A1 (de) * 2001-05-02 2002-11-07 Linde Ag Verfahren zum Abtrennen von Stickstoff aus einer Stickstoff-entaltenden Kohlenwasserstoff Fraktion
US9945604B2 (en) * 2014-04-24 2018-04-17 Air Products And Chemicals, Inc. Integrated nitrogen removal in the production of liquefied natural gas using refrigerated heat pump
US9816754B2 (en) 2014-04-24 2017-11-14 Air Products And Chemicals, Inc. Integrated nitrogen removal in the production of liquefied natural gas using dedicated reinjection circuit
US20150308737A1 (en) 2014-04-24 2015-10-29 Air Products And Chemicals, Inc. Integrated Nitrogen Removal in the Production of Liquefied Natural Gas Using Intermediate Feed Gas Separation
CN114593559B (zh) * 2020-12-04 2024-03-26 惠生清洁能源科技集团股份有限公司 一种应用于flng的bog精馏脱氮装置

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0090469A2 (de) * 1982-03-26 1983-10-05 Union Carbide Corporation Verfahren zum Trennen von Stickstoff von Erdgas
EP0132984A1 (de) * 1983-07-15 1985-02-13 Union Carbide Corporation Stickstoffabscheidungsverfahren von Erdgas
US4662919A (en) * 1986-02-20 1987-05-05 Air Products And Chemicals, Inc. Nitrogen rejection fractionation system for variable nitrogen content natural gas
FR2682964A1 (fr) * 1991-10-23 1993-04-30 Elf Aquitaine Procede de deazotation d'un melange liquefie d'hydrocarbures consistant principalement en methane.

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4504295A (en) * 1983-06-01 1985-03-12 Air Products And Chemicals, Inc. Nitrogen rejection from natural gas integrated with NGL recovery

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0090469A2 (de) * 1982-03-26 1983-10-05 Union Carbide Corporation Verfahren zum Trennen von Stickstoff von Erdgas
EP0132984A1 (de) * 1983-07-15 1985-02-13 Union Carbide Corporation Stickstoffabscheidungsverfahren von Erdgas
US4662919A (en) * 1986-02-20 1987-05-05 Air Products And Chemicals, Inc. Nitrogen rejection fractionation system for variable nitrogen content natural gas
FR2682964A1 (fr) * 1991-10-23 1993-04-30 Elf Aquitaine Procede de deazotation d'un melange liquefie d'hydrocarbures consistant principalement en methane.

Cited By (35)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1131144A2 (de) * 1998-10-22 2001-09-12 Exxonmobil Upstream Research Company Verfahren zur trennung eines einspeisungsstroms mit mehreren komponenten durch destillation
EP1131144A4 (de) * 1998-10-22 2004-09-08 Exxonmobil Upstream Res Co Verfahren zur trennung eines einspeisungsstroms mit mehreren komponenten durch destillation
US6837071B2 (en) 2002-07-16 2005-01-04 The Boc Group Plc Nitrogen rejection method and apparatus
EP1384966A2 (de) * 2002-07-16 2004-01-28 The BOC Group plc Verfahren und Vorrichtung zur Stickstofftrennung
EP1384966A3 (de) * 2002-07-16 2004-02-11 The BOC Group plc Verfahren und Vorrichtung zur Stickstofftrennung
CN100416197C (zh) * 2002-07-16 2008-09-03 英国氧气集团有限公司 排除氮气的方法和设备
US7127915B2 (en) 2002-09-06 2006-10-31 The Boc Group Plc Nitrogen rejection method and apparatus
EP1396694A1 (de) * 2002-09-06 2004-03-10 The BOC Group plc Verfahren und Vorrichtung zur Stickstofftrennung
US6978638B2 (en) 2003-05-22 2005-12-27 Air Products And Chemicals, Inc. Nitrogen rejection from condensed natural gas
JP4607990B2 (ja) * 2003-05-22 2011-01-05 エア プロダクツ アンド ケミカルズ インコーポレイテッド 凝縮天然ガスからの窒素除去装置
KR100750578B1 (ko) * 2003-05-22 2007-08-21 에어 프로덕츠 앤드 케미칼스, 인코오포레이티드 농축 천연 가스로부터 질소 제거 방법 및 시스템
WO2004104143A1 (en) * 2003-05-22 2004-12-02 Air Products And Chemicals, Inc. Nitrogen rejection from condensed natural gas
JP2009041017A (ja) * 2003-05-22 2009-02-26 Air Products & Chemicals Inc 凝縮天然ガスからの窒素除去方法
AU2004241309B2 (en) * 2003-05-22 2009-02-26 Air Products And Chemicals, Inc. Nitrogen rejection from condensed natural gas
JP2009052876A (ja) * 2003-05-22 2009-03-12 Air Products & Chemicals Inc 凝縮天然ガスからの窒素除去装置
EP2275520A1 (de) * 2003-05-22 2011-01-19 Air Products and Chemicals, Inc. Abscheidung von Stickstoff aus kondensiertem Erdgas
US7520143B2 (en) 2005-04-22 2009-04-21 Air Products And Chemicals, Inc. Dual stage nitrogen rejection from liquefied natural gas
WO2010040935A2 (fr) * 2008-10-07 2010-04-15 Technip France Procede de production de courants d'azote liquide et gazeux, d'un courant gazeux riche en helium et d'un courant d'hydrocarbures deazote et installation associee
EA020215B1 (ru) * 2008-10-07 2014-09-30 Текнип Франс Способ получения потоков жидкого и газообразного азота, газового потока с высоким содержанием гелия и деазотированного потока углеводородов и установка для его осуществления
CN102216711B (zh) * 2008-10-07 2015-05-27 泰克尼普法国公司 液态和气态氮物流、富氦气流,和脱氮的碳氢化合物物流的生产方法和相关的设备
FR2936864A1 (fr) * 2008-10-07 2010-04-09 Technip France Procede de production de courants d'azote liquide et gazeux, d'un courant gazeux riche en helium et d'un courant d'hydrocarbures deazote et installation associee.
WO2010040935A3 (fr) * 2008-10-07 2011-06-03 Technip France Procede de production de courants d'azote liquide et gazeux, d'un courant gazeux riche en helium et d'un courant d'hydrocarbures deazote et installation associee
CN102216711A (zh) * 2008-10-07 2011-10-12 泰克尼普法国公司 液态和气态氮物流、富氦气流，和脱氮的碳氢化合物物流的生产方法和相关的设备
WO2010051970A3 (de) * 2008-11-06 2012-08-30 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2010051971A3 (de) * 2008-11-06 2012-08-30 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2010051970A2 (de) * 2008-11-06 2010-05-14 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2010051971A2 (de) * 2008-11-06 2010-05-14 Linde Aktiengesellschaft Verfahren zum abtrennen von stickstoff
WO2011064605A3 (en) * 2009-11-30 2013-04-04 Costain Oil, Gas & Process Limited Process and apparatus for separation of nitrogen from lng
US20170343257A1 (en) * 2014-12-26 2017-11-30 Mitsubishi Heavy Industries Compressor Corporation Gas recovery system for compressor, compressor system, and refrigeration cycle system
EP3225940A4 (de) * 2014-12-26 2018-01-03 Mitsubishi Heavy Industries Compressor Corporation Gasrückgewinnungssystem für verdichter, verdichtersystem und kühlkreislaufsystem
US11067320B2 (en) 2014-12-26 2021-07-20 Mitsubishi Heavy Industries Compressor Corporation Gas recovery system for compressor, compressor system, and refrigeration cycle system
WO2020219299A1 (en) * 2019-04-23 2020-10-29 Chart Energy & Chemicals, Inc. Single column nitrogen rejection unit with side draw heat pump reflux system and method
CN114127500A (zh) * 2019-04-23 2022-03-01 查特能源化工股份有限公司 具有侧吸式热泵回流系统的单塔脱氮装置和方法
US11686528B2 (en) 2019-04-23 2023-06-27 Chart Energy & Chemicals, Inc. Single column nitrogen rejection unit with side draw heat pump reflux system and method
CN114127500B (zh) * 2019-04-23 2024-04-12 查特能源化工股份有限公司 具有侧吸式热泵回流系统的单塔脱氮装置和方法

Also Published As

Publication number Publication date
GB2297825A (en) 1996-08-14
DE69602771T2 (de) 1999-10-21
NO960429D0 (no) 1996-02-01
GB9502126D0 (en) 1995-03-22
EP0725256B1 (de) 1999-06-09
NO960429L (no) 1996-08-05
NO308628B1 (no) 2000-10-02
DE69602771D1 (de) 1999-07-15

Similar Documents

Publication Publication Date Title
US5617741A (en) Dual column process to remove nitrogen from natural gas
EP0231949B2 (de) Stickstoff-Methan-Trennverfahren
EP0725256B1 (de) Verfahren zur Entfernung von Stickstoff aus Erdgas
US4715873A (en) Liquefied gases using an air recycle liquefier
AU755559B2 (en) A process for separating a multi-component pressurized feed stream using distillation
JP4216765B2 (ja) 凝縮天然ガスからの窒素除去方法及び装置
US4411677A (en) Nitrogen rejection from natural gas
US4605427A (en) Cryogenic triple-pressure air separation with LP-to-MP latent-heat-exchange
US7552599B2 (en) Air separation process utilizing refrigeration extracted from LNG for production of liquid oxygen
US4878932A (en) Cryogenic rectification process for separating nitrogen and methane
EP3679310B1 (de) System und verfahren zur gewinnung von neon und anderen nichtkondensierbaren gasen, sowie von xenon und krypton aus einer luftzerlegungsanlage
EP0425738B2 (de) Herstellungsverfahren für Hochdruckstickstoff mit einem geteilten Kondensator-Verdampfer
CA2573429A1 (en) Low temperature air separation process for producing pressurized gaseous product
EP1258690B1 (de) Stickstofftrennungsverfahren
EP0646755B1 (de) Verfahren und Vorrichtung zur Tieftemperaturzerlegung von Luft für die Herstellung von Stickstoff unter erhöhtem Druck mittels gepumpten flüssigen Stickstoffs
US20160123663A1 (en) Air separation method
US5129932A (en) Cryogenic process for the separation of air to produce moderate pressure nitrogen
US5077978A (en) Cryogenic process for the separation of air to produce moderate pressure nitrogen
EP1318368A1 (de) Luftzerlegungsverfahren zur Produktion von gasförmigem Produkt mit variabeler Durchflussmenge

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

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): DE GB NL

17P Request for examination filed

Effective date: 19960729

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

17Q First examination report despatched

Effective date: 19980921

GRAG Despatch of communication of intention to grant

Free format text: ORIGINAL CODE: EPIDOS AGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAH Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOS IGRA

GRAA (expected) grant

Free format text: ORIGINAL CODE: 0009210

AK Designated contracting states

Kind code of ref document: B1

Designated state(s): DE GB NL

RIN1 Information on inventor provided before grant (corrected)

Inventor name: MCNEIL, BRIAN A.

REF Corresponds to:

Ref document number: 69602771

Country of ref document: DE

Date of ref document: 19990715

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: NL

Payment date: 19991213

Year of fee payment: 5

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: DE

Payment date: 19991229

Year of fee payment: 5

PLBE No opposition filed within time limit

Free format text: ORIGINAL CODE: 0009261

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

Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT

26N No opposition filed
PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: NL

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20010901

NLV4 Nl: lapsed or anulled due to non-payment of the annual fee

Effective date: 20010901

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: DE

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20011201

REG Reference to a national code

Ref country code: GB

Ref legal event code: IF02

PGFP Annual fee paid to national office [announced via postgrant information from national office to epo]

Ref country code: GB

Payment date: 20050110

Year of fee payment: 10

PG25 Lapsed in a contracting state [announced via postgrant information from national office to epo]

Ref country code: GB

Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES

Effective date: 20060201

GBPC Gb: european patent ceased through non-payment of renewal fee

Effective date: 20060201