EP2551619A1 - Method and device for extracting pressurised oxygen and pressurised nitrogen by cryogenic decomposition of air - Google Patents

Method and device for extracting pressurised oxygen and pressurised nitrogen by cryogenic decomposition of air Download PDF

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Publication number
EP2551619A1
EP2551619A1 EP11006132A EP11006132A EP2551619A1 EP 2551619 A1 EP2551619 A1 EP 2551619A1 EP 11006132 A EP11006132 A EP 11006132A EP 11006132 A EP11006132 A EP 11006132A EP 2551619 A1 EP2551619 A1 EP 2551619A1
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Prior art keywords
pressure
column
nitrogen
low
oxygen
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EP11006132A
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German (de)
French (fr)
Inventor
Alexander Dr. Alekseev
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Linde GmbH
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Linde GmbH
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Priority to EP11006132A priority Critical patent/EP2551619A1/en
Priority to CN201210319498.9A priority patent/CN102901322B/en
Priority to US13/558,529 priority patent/US20130047666A1/en
Publication of EP2551619A1 publication Critical patent/EP2551619A1/en
Withdrawn legal-status Critical Current

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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
    • 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
    • F25J3/04—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 for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/04084—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression 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
    • 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
    • F25J3/04—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 for air
    • F25J3/04006—Providing pressurised feed air or process streams within or from the air fractionation unit
    • F25J3/04078—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression
    • F25J3/0409—Providing pressurised feed air or process streams within or from the air fractionation unit providing pressurized products by liquid compression and vaporisation with cold recovery, i.e. so-called internal compression of oxygen
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04284—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams
    • F25J3/0429—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion using internal refrigeration by open-loop gas work expansion, e.g. of intermediate or oxygen enriched (waste-)streams of feed air, e.g. used as waste or product air or expanded into an auxiliary column
    • F25J3/04296—Claude expansion, i.e. expanded into the main or high pressure 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
    • 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
    • F25J3/04—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 for air
    • F25J3/04248—Generation of cold for compensating heat leaks or liquid production, e.g. by Joule-Thompson expansion
    • F25J3/04375—Details relating to the work expansion, e.g. process parameter etc.
    • F25J3/04387—Details relating to the work expansion, e.g. process parameter etc. using liquid or hydraulic turbine expansion
    • 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
    • F25J3/04—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 for air
    • F25J3/04436—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 for air using at least a triple pressure main column system
    • F25J3/04454—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 for air using at least a triple pressure main column system a main column system not otherwise provided, e.g. serially coupling of columns or more than three pressure levels
    • 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
    • F25J2200/10—Processes or apparatus using separation by rectification in a quadruple, or more, column or pressure 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
    • F25J2200/20—Processes or apparatus using separation by rectification in an elevated pressure multiple column system wherein the lowest pressure column is at a pressure well above the minimum pressure needed to overcome pressure drop to reject the products to atmosphere
    • 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
    • F25J2235/00—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams
    • F25J2235/52—Processes or apparatus involving steps for increasing the pressure or for conveying of liquid process streams the fluid being oxygen enriched compared to air ("crude oxygen")
    • 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
    • F25J2240/10—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being air
    • 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
    • F25J2240/44—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval 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
    • F25J2240/40—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval
    • F25J2240/46—Expansion without extracting work, i.e. isenthalpic throttling, e.g. JT valve, regulating valve or venturi, or isentropic nozzle, e.g. Laval the fluid being oxygen
    • 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
    • F25J2250/20—Boiler-condenser with multiple exchanger cores in parallel or with multiple re-boiling or condensing streams

Definitions

  • the invention relates to a process for obtaining compressed nitrogen and pressure oxygen by cryogenic separation of air according to the preamble of patent claim 1.
  • the distillation column system of the invention may be designed as a two-column system (for example as a classic Linde double column system), or as a triple or multi-column system. It may in addition to the columns for nitrogen-oxygen separation, further devices for obtaining high purity products and / or other air components, in particular of noble gases, for example, an argon production and / or a krypton-xenon recovery.
  • printed product pressure oxygen product, compressed nitrogen product
  • pressure oxygen product compressed nitrogen product
  • Unreactive nitrogen refers to a fraction containing at least 80% nitrogen. These and all other percentages are to be understood as molar amounts.
  • the "main heat exchanger” is used to cool feed air in indirect heat exchange with backflow from the distillation column system for nitrogen-oxygen separation (or from other columns).
  • the main heat exchanger may be formed of one or more parallel and / or serially connected heat exchanger sections, for example one or more plate heat exchanger blocks.
  • condenser-evaporator refers to a heat exchanger in which a first condensing fluid stream undergoes indirect heat exchange with a second evaporating fluid stream.
  • Each condenser-evaporator has a liquefaction space and an evaporation space, which consist of liquefaction passages or evaporation passages.
  • the condensation (liquefaction) of a first fluid flow is performed, in the evaporation space the evaporation of a second fluid flow.
  • Evaporation and liquefaction space are formed by groups of passages that are in heat exchange relationship with each other.
  • the inventive method is particularly suitable for systems for the simultaneous production of pressure oxygen and large amounts of pressurized nitrogen; For example, 50 to 70% of the total amount of air is recovered as pressurized nitrogen. It can also be more pressure nitrogen fractions are produced at different pressures when they are needed by nitrogen consumers, as occurs for example in IGCC plants (gas and steam turbine power plant with integrated coal or heavy oil gasification).
  • IGCC plants gas and steam turbine power plant with integrated coal or heavy oil gasification
  • residual gas impurity nitrogen stream 10 to 30% of the total amount of air
  • residual gas impurity nitrogen stream 10 to 30% of the total amount of air
  • energy of this gas should be utilized in the plant.
  • the conventional solution is that the residual gas in a Heat exchanger is heated, then in a turbine (residual gas turbine) is relaxed to a corresponding low pressure. The residual gas cools down. The cold residual gas is passed through the main heat exchanger and cools warmer streams.
  • Such processes are over EP 384483 B1 ( US 5036672 ) or US 3886758 known.
  • the invention is therefore based on the object to provide a method of the type mentioned above and a corresponding device, which are economically particularly favorable and require relatively low investment costs and / or provide a particularly high stability during operation, especially at relatively low energy consumption.
  • residual gas column To recover the pressure energy from the impure nitrogen stream, an additional separation column is used instead of the residual gas turbine, which is referred to as residual gas column.
  • the impure nitrogen stream from the low-pressure column is first liquefied in an additional condenser-evaporator, which is located in the bottom of the residual gas column and then expanded in a throttle valve to the required low pressure.
  • the expanded liquid is passed from above into this additional separation column and serves as reflux for the separation process.
  • this additional separation column is cooled from above, it is heated from below by the sump heater.
  • This column is used to pre-separate the crude oxygen liquid from the bottom of the high pressure column. (In a three-column system may additionally or alternatively at least a portion of the bottom liquid of the medium-pressure column be introduced.)
  • This liquid is fed approximately in the middle of the column ("first intermediate point" of the residual gas column).
  • the gas from the residual gas column is then at a correspondingly low pressure.
  • the bottom liquid is oxygen-rich than the crude oxygen from the high-pressure column and can be fed at a corresponding point in another column of the distillation column system for nitrogen-oxygen separation.
  • the distillation column system for nitrogen-oxygen separation preferably has a main condenser, which is designed as a condenser-evaporator. About him are the head of the high pressure column and the bottom of the low pressure column in heat exchanging connection.
  • a liquid sump fraction is taken from the residual gas column and the low pressure column is fed to a second intermediate point, which is below the first intermediate point. Since the residual gas column is operated at a lower pressure than the low-pressure column, the pressure in the liquid bottom fraction must be increased before it is introduced into the low-pressure column, for example by a pump.
  • a gaseous residual stream is withdrawn from the top of the residual gas column and warmed in the main heat exchanger.
  • no increase in pressure is carried out in the impure nitrogen stream between the low-pressure column and the bottom evaporator, and in particular the liquefaction space of the bottom evaporator is operated substantially below the operating pressure of the low-pressure column.
  • the pressure oxygen product may in principle be recovered under the operating pressure of the low pressure column (minus line losses) or further compressed downstream of the main heat exchanger in an oxygen compressor
  • At least a portion of the (pseudo) liquefied feed air can be supplied to the residual gas column in this case, namely at a second intermediate point, which is above the first intermediate point at which the crude oxygen fraction is introduced from the high-pressure column.
  • the low-pressure column preferably has no top condenser.
  • the reflux liquid in the upper region of the residual gas column is in particular formed exclusively by the expanded impure nitrogen stream.
  • the low-pressure column also preferably has no top condenser.
  • As reflux liquid in the upper region of the low-pressure column liquid nitrogen from the high-pressure column is used instead.
  • liquid nitrogen from the medium-pressure column it is additionally or alternatively possible to add liquid nitrogen from the medium-pressure column as reflux to the low-pressure column.
  • the invention also relates to a device according to claim 9.
  • the device according to the invention can be supplemented by device features which correspond to the features of the dependent method claims.
  • FIG. 1 atmospheric air is sucked in via line 1 from a main air compressor 2 and compressed to a pressure of about 10 bar.
  • the compressed feed air 3 is cooled in a pre-cooler 4 and then cleaned in a cleaning device 5 containing molecular sieve adsorber, that is freed in particular of water and carbon dioxide.
  • the compressed and purified feed air 6 is divided into three partial streams 10, 20, 30.
  • a first partial flow 10 (direct air flow) is fed without further pressure increase the warm end of a main heat exchanger 8, cooled there to about dew point and fed via lines 11 and 12 of the high pressure column 50 of a distillation column system for nitrogen-oxygen separation, which also has a low pressure column 51 and a main capacitor 53.
  • the main heat exchanger may be formed from a single or multiple parallel and / or serially connected heat exchanger sections, for example one or more plate heat exchanger blocks.
  • the operating pressures in the high-pressure column and the low-pressure column (in each case at the top) are 9.7 bar and approx. 3.0 bar, respectively.
  • the second and the third partial flow 20, 30 are first fed together via line 7 to a first motor-driven booster 9 with aftercooler 15 and there recompressed to an intermediate pressure of about 20 bar.
  • the second partial flow 20 (turbine flow) is further compressed in a turbine-driven secondary compressor 21 with aftercooler 22 to about 28 bar and fed under this pressure via line 23 to the warm end of the main heat exchanger 8.
  • At an intermediate temperature it is withdrawn via line 24, in an expansion turbine 25 working to relax at about high-pressure column pressure and finally introduced via lines 26 and 12 in the high-pressure column.
  • a generator turbine and to eliminate supercharger 21 and aftercooler 22 (not shown).
  • the third partial flow 30 is brought from the intermediate pressure in a second motor-driven booster 31 with aftercooler 32 to a high pressure of 60 bar, passed via line 33 to the main heat exchanger 8 and there cooled and (pseudo-) liquefied. Subsequently, the third partial stream 33 is expanded in an expansion valve 34 to about high pressure column pressure and introduced via line 35 in the distillation column system for nitrogen-oxygen separation, at least partially in liquid form. Alternatively, the relaxation is performed in a turbine 36 which is coupled to a generator 37. A portion 38, 39 of the liquid air may be cooled in a supercooling countercurrent 54 and supplied to the low pressure column 51 at a suitable intermediate point.
  • the gaseous top nitrogen 55 of the high-pressure column 50 is liquefied to a first part 56 in the main condenser 53.
  • a first part 58 of the liquid nitrogen 57 produced in the process is fed as reflux to the high-pressure column 50.
  • a second part 66, 67 is cooled in the subcooling countercurrent 54 and fed to the head of the low pressure column 51 as reflux.
  • a nitrogen-rich intermediate fraction 68, 69 is cooled in the subcooling countercurrent 54 and fed to the low pressure column 51 at an intermediate point.
  • the oxygen-enriched bottoms fraction 70 from the high-pressure column 50 is also cooled in the subcooling countercurrent 54 and fed to a first part 71 of the low-pressure column 51 at another intermediate point.
  • pressurized nitrogen product is recovered under four different pressures.
  • two nitrogen product streams are withdrawn directly from the distillation column nitrogen-oxygen separation system in gas, and heated in the main heat exchanger 8 to about ambient temperature, namely gaseous overhead nitrogen 73, 74, 75 of the low pressure column 51 as low pressure column pressure (GAN) pressurized nitrogen product and a second Part 72, 76 of the top nitrogen 55 of the high pressure column as pressurized nitrogen product under high pressure column pressure (PGAN1).
  • GAN low pressure column pressure
  • PGAN1 pressurized nitrogen product
  • a third part 59 of the liquid nitrogen 57 from the main condenser 53 is fed to a nitrogen internal compression. He will be in one
  • Nitrogen pump 60 brought in the liquid state to an increased nitrogen pressure above the operating pressure of the high pressure column, passed via line 61 to the main heat exchanger 8, there in indirect heat exchange with feed air (pseudo) evaporated and warmed to about ambient temperature and finally under the increased pressure via line 62 as gaseous pressure nitrogen product (ICGAN2) won.
  • a portion 63 of the pumped nitrogen may be throttled in an expansion valve 64 to an intermediate pressure between the high pressure column pressure and the increased nitrogen pressure and recovered under this intermediate pressure as another gaseous pressure nitrogen product 65 (ICGAN1).
  • a pressure oxygen product could be obtained by gaseous removal immediately above the bottom of the low pressure column 51 and then heating in the main heat exchanger at about low pressure column pressure and further compressed in an oxygen compressor if necessary (external compression).
  • it is more favorable here to apply an internal compression by taking an oxygen stream 77 in the liquid state from the lower region of the low-pressure column 51, here directly at the bottom or from the evaporation space of the main condenser 53.
  • the oxygen flow 77 becomes a liquid state Pressure increase to an increased oxygen pressure in an oxygen pump 78 subjected and vaporized in the main heat exchanger 8 in indirect heat exchange with feed air or pseudo-vaporized, wherein a portion of the feed air is liquefied or pseudo-liquefied.
  • At least a first part 80, 81 of the pumped oxygen 79 is thereby obtained as a pressure oxygen product (HP-GOX) under the increased oxygen pressure.
  • Another part 82, 84 of the pumped oxygen 79 can be throttled in an expansion valve 83 to an intermediate pressure between the low-pressure column pressure and the increased oxygen pressure and recovered under this intermediate pressure as another gaseous pressure oxygen product (MP-GOX).
  • a gaseous impure nitrogen stream 85 is taken from the low-pressure column which is less pure than the top nitrogen 73 but contains at least 80% nitrogen. In the embodiment, its nitrogen content is 90%. According to the invention, this stream is used to operate a residual gas column 52, which has a bottom evaporator 85 and is operated at a pressure of 1.4 bar at the top. Of the Impurity stream 85 is introduced into the liquefaction space of the bottom evaporator where it is brought into indirect heat exchange with the bottom liquid of the residual gas column 52 and thereby at least partially condensed. The at least partially liquefied impure nitrogen stream 87 is expanded in a throttle valve 88 to the operating pressure of the residual gas column and introduced into the upper region of the residual gas column 52, in particular directly at the top of the column.
  • a crude liquid oxygen fraction 89 from the high-pressure column 50 is further enriched. It is formed by a portion of the bottom fraction 70, from which it is branched downstream of the subcooling countercurrent 54.
  • the liquid crude oxygen fraction 89 is expanded in an expansion valve 90 and fed to the residual gas column 52 at a first intermediate point.
  • the residual gas column is also fed at a second intermediate point, a partial flow 90 of the liquid air 38 after cooling in the subcooling countercurrent 54.
  • the liquid bottoms fraction 91 of the residual gas column is enriched more strongly with oxygen than the crude oxygen fraction 89 from the high-pressure column 50 and is brought by means of a pump 92 over to the higher pressure of the low-pressure column 51. It is supplied to the low-pressure column via line 93 at a second intermediate point, which is below the first intermediate point at which the impure nitrogen stream 85 is withdrawn. The second intermediate point is also below the feed point of the crude oxygen 71, which is passed directly from the high pressure column 50 in the low pressure column 51.
  • a nitrogen-rich residual stream 94, 95, 96 is withdrawn in gaseous form and in the subcooling countercurrent 54 and in. Main heat exchanger 8 warmed up. If desired, the warm residual gas 96 can still be used as a regeneration gas for the purification unit 5 and / or in an evaporative cooler of the precooling unit 4.
  • FIG. 2 differs from FIG. 1 in that the process also uses a medium pressure column 200 known from three column systems.
  • the medium-pressure column 200 each has a condenser-evaporator as a bottom evaporator 201 and top condenser 202 and is operated under a pressure which is between the operating pressures of low pressure column and high pressure column, in the example at 6 bar.
  • a portion 201 of the sump fraction 70 of the high-pressure column 50 is fed to the medium-pressure column 200 as an insert.
  • a portion 204 of the liquid air 38 can be fed into the medium-pressure column 200.
  • the bottom liquid 205 of the medium-pressure column 200 is partially evaporated in the top condenser 202 of the medium-pressure column 200 and then fed via the lines 206 and 207 at a suitable point in the low-pressure column 51.
  • the gaseous top nitrogen of the medium-pressure column 200 is, as far as it is not condensed in the top condenser 202, passed via line 208 to the main heat exchanger 8 and recovered via line 209 as a further pressure nitrogen product under medium pressure column pressure (PGAN2).
  • this fraction can be analogous to FIG. 1 (Line 93) are fed exclusively or partially into the low-pressure column 51.
  • the feed into the low-pressure column 51 preferably takes place at the same level as the feed of the liquid fraction 207 remaining from the evaporation space of the top condenser 202 of the medium-pressure column.

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Abstract

The method involves cooling compressed and purified insertion air (6) in a main heat exchanger (8) and introducing the insertion air in a distilation column-system for nitrogen-oxygen separation. A low pressure column (51) is operated under a pressure of 2 bar. The distilation column system for nitrogen-oxygen separation has an external residual gas column (52). The operating pressure of the residual gas column is lower than the operating pressure of a low pressure column. An independent claim is included for a device for producing pressurized nitrogen and compressed oxygen by low temperature analysis of air.

Description

Die Erfindung betrifft ein Verfahren zur Gewinnung von Druckstickstoff und Drucksauerstoff durch Tieftemperaturzerlegung von Luft gemäß dem Oberbegriff des Patentanspruchs 1.The invention relates to a process for obtaining compressed nitrogen and pressure oxygen by cryogenic separation of air according to the preamble of patent claim 1.

Verfahren und Vorrichtungen zur Tieftemperaturzerlegung von Luft sind zum Beispiel aus Hausen/Linde, Tieftemperaturtechnik, 2. Auflage 1985, Kapitel 4 (Seiten 281 bis 337 ) bekannt.For example, methods and apparatus for cryogenic decomposition of air are off Hausen / Linde, Tiefftemperaturtechnik, 2nd edition 1985, chapter 4 (pages 281 to 337 ) known.

Das Destilliersäulen-System der Erfindung kann als Zwei-Säulen-System (zum Beispiel als klassisches Linde-Doppelsäulensystem) ausgebildet sein, oder auch als Drei- oder Mehr-Säulen-System. Es kann zusätzlich zu den Kolonnen zur Stickstoff-Sauerstoff-Trennung weitere Vorrichtungen zur Gewinnung hochreiner Produkte und/oder anderer Luftkomponenten, insbesondere von Edelgasen aufweisen, beispielsweise eine Argongewinnung und/oder eine Krypton-Xenon-Gewinnung.The distillation column system of the invention may be designed as a two-column system (for example as a classic Linde double column system), or as a triple or multi-column system. It may in addition to the columns for nitrogen-oxygen separation, further devices for obtaining high purity products and / or other air components, in particular of noble gases, for example, an argon production and / or a krypton-xenon recovery.

Unter "Druckprodukt" (Drucksauerstoffprodukt, Druckstickstoffprodukt) wird hier das Endprodukt einer Luftzerlegungsanlage verstanden, das unter einem Druck steht, der mindestens 0,5 bar über dem Atmosphärendruck liegt und insbesondere mindestens 2 bar beträgt.By "printed product" (pressure oxygen product, compressed nitrogen product) is meant here the end product of an air separation plant which is under a pressure which is at least 0.5 bar above the atmospheric pressure and in particular at least 2 bar.

"Unreinstickstoff" bezeichnet hier eine Fraktion, die mindestens 80 % Stickstoff enthält. Diese und alle weiteren Prozentangaben sind als molare Mengen zu verstehen."Unreactive nitrogen" refers to a fraction containing at least 80% nitrogen. These and all other percentages are to be understood as molar amounts.

Der "Hauptwärmetauscher" dient zur Abkühlung von Einsatzluft in indirektem Wärmeaustausch mit Rückströmen aus dem Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung (oder aus weiteren Säulen). Der Hauptwärmetauscher kann aus einem oder mehreren parallel und/oder seriell verbundenen Wärmetauscherabschnitten gebildet sein, zum Beispiel aus einem oder mehreren Plattenwärmetauscher-Blöcken.The "main heat exchanger" is used to cool feed air in indirect heat exchange with backflow from the distillation column system for nitrogen-oxygen separation (or from other columns). The main heat exchanger may be formed of one or more parallel and / or serially connected heat exchanger sections, for example one or more plate heat exchanger blocks.

Als "Kondensator-Verdampfer" wird ein Wärmetauscher bezeichnet, in dem ein erster kondensierender Fluidstrom in indirekten Wärmeaustausch mit einem zweiten verdampfenden Fluidstrom tritt. Jeder Kondensator-Verdampfer weist einen Verflüssigungsraum und einen Verdampfungsraum auf, die aus Verflüssigungspassagen beziehungsweise Verdampfungspassagen bestehen. In dem Verflüssigungsraum wird die Kondensation (Verflüssigung) eines ersten Fluidstroms durchgeführt, in dem Verdampfungsraum die Verdampfung eines zweiten Fluidstroms. Verdampfungs- und Verflüssigungsraum werden durch Gruppen von Passagen gebildet, die untereinander in Wärmeaustauschbeziehung stehen.The term "condenser-evaporator" refers to a heat exchanger in which a first condensing fluid stream undergoes indirect heat exchange with a second evaporating fluid stream. Each condenser-evaporator has a liquefaction space and an evaporation space, which consist of liquefaction passages or evaporation passages. In the liquefaction space, the condensation (liquefaction) of a first fluid flow is performed, in the evaporation space the evaporation of a second fluid flow. Evaporation and liquefaction space are formed by groups of passages that are in heat exchange relationship with each other.

Das erfindungsgemäße Verfahren ist insbesondere geeignet für Anlagen zur gleichzeitigen Erzeugung von Drucksauerstoff und großen Mengen an Druckstickstoff; zum Beispiel werden 50 bis 70 % der Gesamtluftmenge als Druckstickstoff gewonnen. Es können auch mehrere Druckstickstoff-Fraktionen bei unterschiedlichen Drücken erzeugt werden, wenn diese von Stickstoff-Verbraucher benötigt werden, wie es beispielsweise bei IGCC-Anlagen (Gas- und Dampfturbinen-Kraftwerk mit integrierter Kohle- oder Schwerölvergasung) vorkommt.The inventive method is particularly suitable for systems for the simultaneous production of pressure oxygen and large amounts of pressurized nitrogen; For example, 50 to 70% of the total amount of air is recovered as pressurized nitrogen. It can also be more pressure nitrogen fractions are produced at different pressures when they are needed by nitrogen consumers, as occurs for example in IGCC plants (gas and steam turbine power plant with integrated coal or heavy oil gasification).

In diesem Fall kann es sich lohnen, den Gesamtdruckniveau des Destilliersäulen-Systems zur Stickstoff-Sauerstoff-Trennung zu erhöhen und die Niederdrucksäule mit mehr als 2 bar, insbesondere 2 bis 10 bar, beispielsweise 3 bis 5 bar zu betreiben. Der Druck in der Hochdrucksäule (und in der Mitteldrucksäule, falls das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung als Drei-Säulen-System ausgestaltet ist) muss entsprechend angepasst werden (Hochdrucksäulendruck = etwa 4 ● Niederdrucksäulendruck ^ 0,8). Alle Hardware-Komponenten wie Trennkolonnen und Wärmetauscher können dann etwas kompakter und daher kostengünstiger gestaltet werden. Außerdem ergibt sich ein energetischer Vorteil, weil die Temperaturprofile im Hauptwärmetauscher günstiger sind und das Druckverhältnis zwischen Hochdrucksäule und Niederdrucksäule-Druck kleiner wird.In this case, it may be worthwhile to increase the overall pressure level of the distillation column system for nitrogen-oxygen separation and to operate the low-pressure column with more than 2 bar, in particular 2 to 10 bar, for example 3 to 5 bar. The pressure in the high-pressure column (and in the medium-pressure column, if the distillation column system for nitrogen-oxygen separation is designed as a three-column system) must be adjusted accordingly (high-pressure column pressure = about 4 ● low-pressure column pressure ^ 0.8). All hardware components such as separation columns and heat exchangers can then be made somewhat more compact and therefore less expensive. In addition, there is an energetic advantage because the temperature profiles in the main heat exchanger are cheaper and the pressure ratio between the high pressure column and low pressure column pressure is smaller.

Auch der üblicherweise als Restgas bezeichnete Unreinstickstoffstrom (10 bis 30 % der Gesamtluftmenge) weist am Austritt aus dem Destilliersäulen-System den erhöhten Druck auf, unter dem die Niederdrucksäule betrieben wird. Um das Verfahren möglichst effizient zu gestalten, sollte Energie dieses Gases in der Anlage verwertet werden. Die konventionelle Lösung besteht darin, dass das Restgas in einem Wärmetauscher angewärmt wird, danach in einer Turbine (Restgasturbine) auf einen entsprechenden niedrigen Druck entspannt wird. Dabei kühlt sich das Restgas ab. Das kalte Restgas wird wieder durch den Hauptwärmetauscher geleitet und kühlt dabei wärmere Ströme ab. Derartige Prozesse sind aus EP 384483 B1 ( US 5036672 ) oder US 3886758 bekannt.Also commonly referred to as residual gas impurity nitrogen stream (10 to 30% of the total amount of air) has at the outlet from the distillation column system, the increased pressure at which the low pressure column is operated. To make the process as efficient as possible, energy of this gas should be utilized in the plant. The conventional solution is that the residual gas in a Heat exchanger is heated, then in a turbine (residual gas turbine) is relaxed to a corresponding low pressure. The residual gas cools down. The cold residual gas is passed through the main heat exchanger and cools warmer streams. Such processes are over EP 384483 B1 ( US 5036672 ) or US 3886758 known.

Der Nachteil dieser Lösung besteht darin, dass eine Turbine zum Entspannen von Restgas benötigt wird. Da relativ große Gasmengen von relativ niedrigem Druck auf einen ganz niedrigen Druck entspannt werden, ist diese Turbine in der Regel groß und deswegen teuer. Auch die Gesamtverfügbarkeit der Anlage wird durch diese Turbine beeinflusst, da die Verfügbarkeit der Turbine nicht so hoch ist, verglichen mit typischen Apparaten wie Trennkolonne oder Wärmetauscher.The disadvantage of this solution is that a turbine is required for the expansion of residual gas. Since relatively large amounts of gas are relieved from a relatively low pressure to a very low pressure, this turbine is usually large and therefore expensive. The overall availability of the plant is also influenced by this turbine, since the availability of the turbine is not so high compared to typical apparatus such as separation column or heat exchanger.

Der Erfindung liegt daher die Aufgabe zugrunde, ein Verfahren der eingangs genannten Art und eine entsprechende Vorrichtung anzugeben, die wirtschaftlich besonders günstig sind und insbesondere bei relativ geringem Energieverbrauch relativ niedrige Investitionskosten erfordern und/oder eine besonders hohe Stabilität im Betrieb bieten.The invention is therefore based on the object to provide a method of the type mentioned above and a corresponding device, which are economically particularly favorable and require relatively low investment costs and / or provide a particularly high stability during operation, especially at relatively low energy consumption.

Diese Aufgabe wird durch die kennzeichnenden Merkmale des Patentanspruchs 1 gelöst.This object is solved by the characterizing features of claim 1.

Zur Rückgewinnung der Druckenergie aus dem Unreinstickstoffstrom wird anstelle der Restgasturbine eine zusätzliche Trennsäule eingesetzt, die als Restgassäule bezeichnet wird.To recover the pressure energy from the impure nitrogen stream, an additional separation column is used instead of the residual gas turbine, which is referred to as residual gas column.

Der Unreinstickstoffstrom aus der Niederdrucksäule wird in einem zusätzlichen Kondensator-Verdampfer, der sich im Sumpf der Restgassäule befindet, zuerst verflüssigt und danach in einem Drosselventil auf den erforderlichen Niederdruck entspannt. Die entspannte Flüssigkeit wird in diese zusätzliche Trennkolonne von oben geleitet und dient als Rücklauf für den Trennvorgang. Auf dieser Weise wird diese zusätzliche Trennkolonne von oben gekühlt, geheizt wird sie von unten durch die Sumpfheizung. Diese Kolonne wird verwendet, um die Rohsauerstoffflüssigkeit aus dem Sumpf der Hochdrucksäule vorzutrennen. (Bei einem Drei-Säulen-System kann zusätzlich oder alternativ mindestens ein Teil der Sumpfflüssigkeit der Mitteldrucksäule eingeleitet werden.) Diese Flüssigkeit wird etwa in der Mitte der Kolonne eingespeist ("erste Zwischenstelle" der Restgassäule). Das Gas aus der Restgassäule liegt dann bei entsprechend niedrigem Druck vor. Die Sumpfflüssigkeit ist sauerstoffreicher als der Rohsauerstoff aus der Hochdrucksäule und kann an einer entsprechenden Stelle in eine andere Säule des Destilliersäulen-Systems zur Stickstoff-Sauerstoff-Trennung eingespeist werden.The impure nitrogen stream from the low-pressure column is first liquefied in an additional condenser-evaporator, which is located in the bottom of the residual gas column and then expanded in a throttle valve to the required low pressure. The expanded liquid is passed from above into this additional separation column and serves as reflux for the separation process. In this way, this additional separation column is cooled from above, it is heated from below by the sump heater. This column is used to pre-separate the crude oxygen liquid from the bottom of the high pressure column. (In a three-column system may additionally or alternatively at least a portion of the bottom liquid of the medium-pressure column be introduced.) This liquid is fed approximately in the middle of the column ("first intermediate point" of the residual gas column). The gas from the residual gas column is then at a correspondingly low pressure. The bottom liquid is oxygen-rich than the crude oxygen from the high-pressure column and can be fed at a corresponding point in another column of the distillation column system for nitrogen-oxygen separation.

Auf diese Weise kann auf eine Restgasturbine verzichtet und trotzdem die Druckenergie des Unreinstickstoffstroms auf überraschend effiziente Weise zurückgewonnen werden.In this way it is possible to dispense with a residual gas turbine and still recover the pressure energy of the impure nitrogen stream in a surprisingly efficient manner.

Das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung weist vorzugsweise einen Hauptkondensator auf, der als Kondensator-Verdampfer ausgebildet ist. Über ihn stehen der Kopf der Hochdrucksäule und der Sumpf der Niederdrucksäule in wärmetauschender Verbindung.The distillation column system for nitrogen-oxygen separation preferably has a main condenser, which is designed as a condenser-evaporator. About him are the head of the high pressure column and the bottom of the low pressure column in heat exchanging connection.

Vorzugsweise wird eine flüssige Sumpffraktion aus der Restgassäule entnommen und der Niederdrucksäule an einer zweiten Zwischenstelle zugeleitet wird, die unterhalb der ersten Zwischenstelle liegt. Da die Restgassäule unter niedrigerem Druck als die Niederdrucksäule betrieben wird, muss der Druck in der flüssigen Sumpffraktion vor deren Einleitung in die Niederdrucksäule erhöht werden, beispielsweise durch eine Pumpe.Preferably, a liquid sump fraction is taken from the residual gas column and the low pressure column is fed to a second intermediate point, which is below the first intermediate point. Since the residual gas column is operated at a lower pressure than the low-pressure column, the pressure in the liquid bottom fraction must be increased before it is introduced into the low-pressure column, for example by a pump.

In einer weiteren Ausgestaltung des erfindungsgemäßen Verfahrens wird vom Kopf der Restgassäule ein gasförmiger Reststrom abgezogen und im Hauptwärmetauscher angewärmt.In a further embodiment of the method according to the invention, a gaseous residual stream is withdrawn from the top of the residual gas column and warmed in the main heat exchanger.

Vorzugsweise wird im Unreinstickstoffstrom zwischen Niederdrucksäule und Sumpfverdampfer keine Druckerhöhung vorgenommen und insbesondere der Verflüssigungsraum des Sumpfverdampfers im Wesentlichen unter dem Betriebsdruck der Niederdrucksäule betrieben wird.Preferably, no increase in pressure is carried out in the impure nitrogen stream between the low-pressure column and the bottom evaporator, and in particular the liquefaction space of the bottom evaporator is operated substantially below the operating pressure of the low-pressure column.

Das Drucksauerstoffprodukt kann grundsätzlich unter dem Betriebsdruck der Niederdrucksäule (abzüglich Leitungsverluste) gewonnen oder stromabwärts des Hauptwärmetauschers in einem Sauerstoffverdichter weiter verdichtet werdenThe pressure oxygen product may in principle be recovered under the operating pressure of the low pressure column (minus line losses) or further compressed downstream of the main heat exchanger in an oxygen compressor

(Außenverdichtung). In vielen Fällen ist es jedoch eine Innenverdichtung günstiger, bei welcher ein Sauerstoffstrom in flüssigem Zustand aus dem unteren Bereich der Niederdrucksäule entnommen, in flüssigem Zustand einer Druckerhöhung unterzogen und im Hauptwärmetauscher in indirektem Wärmeaustausch mit Einsatzluft verdampft oder - bei überkritischem Druck - pseudo-verdampft wird, wobei ein Teil der Einsatzluft verflüssigt oder - bei überkritischem Druck - pseudo-verflüssigt wird.(Outer compression). In many cases, however, it is cheaper internal compression, in which a stream of oxygen removed in the liquid state from the lower region of the low pressure column, subjected to pressure increase in the liquid state and evaporated in the main heat exchanger in indirect heat exchange with feed air or - pseudo-vaporized at supercritical pressure , wherein a portion of the feed air is liquefied or - at supercritical pressure - pseudo-liquefied.

Mindestens ein Teil der (pseudo-)verflüssigten Einsatzluft kann in diesem Fall der Restgassäule zugeleitet werden, und zwar an einer zweiten Zwischenstelle, die oberhalb der ersten Zwischenstelle liegt, an der die Rohsauerstofffraktion aus der Hochdrucksäule eingeleitet wird.At least a portion of the (pseudo) liquefied feed air can be supplied to the residual gas column in this case, namely at a second intermediate point, which is above the first intermediate point at which the crude oxygen fraction is introduced from the high-pressure column.

Vorzugsweise weist die Niederdrucksäule keinen Kopfkondensator auf. Die Rücklaufflüssigkeit im oberen Bereich der Restgassäule wird insbesondere ausschließlich durch den entspannten Unreinstickstoffstrom gebildet.The low-pressure column preferably has no top condenser. The reflux liquid in the upper region of the residual gas column is in particular formed exclusively by the expanded impure nitrogen stream.

Auch die Niederdrucksäule weist vorzugsweise keinen Kopfkondensator auf. Als Rücklaufflüssigkeit im oberen Bereich der Niederdrucksäule wird vielmehr flüssiger Stickstoff aus der Hochdrucksäule eingesetzt. Im Falle eines Drei-Säulen-Systems mit Mitteldrucksäule kann zusätzlich oder alternativ flüssiger Stickstoff aus der Mitteldrucksäule als Rücklauf auf die Niederdrucksäule aufgegeben werden.The low-pressure column also preferably has no top condenser. As reflux liquid in the upper region of the low-pressure column, liquid nitrogen from the high-pressure column is used instead. In the case of a three-column system with a medium-pressure column, it is additionally or alternatively possible to add liquid nitrogen from the medium-pressure column as reflux to the low-pressure column.

Die Erfindung betrifft außerdem eine Vorrichtung gemäß Patentanspruch 9. Die erfindungsgemäße Vorrichtung kann durch Vorrichtungsmerkmale ergänzt werden, die den Merkmalen der abhängigen Verfahrensansprüche entsprechen.The invention also relates to a device according to claim 9. The device according to the invention can be supplemented by device features which correspond to the features of the dependent method claims.

Die Erfindung sowie weitere Einzelheiten der Erfindung werden im Folgenden anhand von in den Zeichnungen schematisch dargestellten Ausführungsbeispielen näher erläutert. Hierbei zeigen:

Figur 1
ein erstes Ausführungsbeispiel für ein erfindungsgemäßes Verfahren und eine entsprechende Vorrichtung, bei dem das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung als Zwei-Säulen-System mit Restgassäule ausgebildet ist.
Figur 2
ein zweites Ausführungsbeispiel, bei dem das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung als Drei-Säulen-System mit Restgassäule ausgebildet ist
The invention and further details of the invention are explained below with reference to embodiments schematically illustrated in the drawings. Hereby show:
FIG. 1
a first embodiment of a method according to the invention and a corresponding device in which the distillation column system for nitrogen-oxygen separation is designed as a two-column system with residual gas column.
FIG. 2
A second embodiment in which the distillation column system for nitrogen-oxygen separation is designed as a three-column system with residual gas column

In Figur 1 wird atmosphärische Luft über Leitung 1 von einem Hauptluftverdichter 2 angesaugt und auf einen Druck von ca. 10 bar verdichtet. Die verdichtete Einsatzluft 3 wird in einer Vorkühleinrichtung 4 gekühlt und anschließend in einer Reinigungseinrichtung 5, die Molekularsieb-Adsorber enthält, gereinigt, das heißt insbesondere von Wasser und Kohlendioxid befreit.In FIG. 1 atmospheric air is sucked in via line 1 from a main air compressor 2 and compressed to a pressure of about 10 bar. The compressed feed air 3 is cooled in a pre-cooler 4 and then cleaned in a cleaning device 5 containing molecular sieve adsorber, that is freed in particular of water and carbon dioxide.

Die verdichtete und gereinigte Einsatzluft 6 wird in drei Teilströme 10, 20, 30 aufgeteilt. Ein erster Teilstrom 10 (Direktluftstrom) wird ohne weitere Druckerhöhung dem warmen Ende eines Hauptwärmetauschers 8 zugeleitet, dort auf etwa Taupunktstemperatur abgekühlt und über die Leitungen 11 und 12 der Hochdrucksäule 50 eines Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung zugeleitet, das außerdem eine Niederdrucksäule 51 und einen Hauptkondensator 53 aufweist. Der Hauptwärmetauscher kann aus einem einzelnen oder mehreren parallel und/oder seriell verbundenen Wärmetauscherabschnitten gebildet sein, zum Beispiel aus einem oder mehreren Plattenwärmetauscher-Blöcken. Die Betriebsdrücke in Hochdrucksäule und Niederdrucksäule (jeweils am Kopf) betragen 9,7 bar beziehungsweise ca. 3,0 bar.The compressed and purified feed air 6 is divided into three partial streams 10, 20, 30. A first partial flow 10 (direct air flow) is fed without further pressure increase the warm end of a main heat exchanger 8, cooled there to about dew point and fed via lines 11 and 12 of the high pressure column 50 of a distillation column system for nitrogen-oxygen separation, which also has a low pressure column 51 and a main capacitor 53. The main heat exchanger may be formed from a single or multiple parallel and / or serially connected heat exchanger sections, for example one or more plate heat exchanger blocks. The operating pressures in the high-pressure column and the low-pressure column (in each case at the top) are 9.7 bar and approx. 3.0 bar, respectively.

Der zweiter und der dritte Teilstrom 20, 30 werden zunächst gemeinsam über Leitung 7 einem ersten motorgetriebenen Nachverdichter 9 mit Nachkühler 15 zugeleitet und dort auf einen Zwischendruck von ca. 20 bar nachverdichtet. Der zweite Teilstrom 20 (Turbinenstrom) wird in einem turbinengetriebenen Nachverdichter 21 mit Nachkühler 22 weiter auf etwa 28 bar verdichtet und unter diesem Druck über Leitung 23 dem warmen Ende des Hauptwärmetauschers 8 zugeleitet. Bei einer Zwischentemperatur wird er über Leitung 24 entnommen, in einer Expansionsturbine 25 arbeitsleistend auf etwa Hochdrucksäulendruck entspannt und schließlich über die Leitungen 26 und 12 in die Hochdrucksäule eingeleitet. Alternativ kann auch eine Generatorturbine eingesetzt werden und Nachverdichter 21 und Nachkühler 22 entfallen (nicht dargestellt).The second and the third partial flow 20, 30 are first fed together via line 7 to a first motor-driven booster 9 with aftercooler 15 and there recompressed to an intermediate pressure of about 20 bar. The second partial flow 20 (turbine flow) is further compressed in a turbine-driven secondary compressor 21 with aftercooler 22 to about 28 bar and fed under this pressure via line 23 to the warm end of the main heat exchanger 8. At an intermediate temperature, it is withdrawn via line 24, in an expansion turbine 25 working to relax at about high-pressure column pressure and finally introduced via lines 26 and 12 in the high-pressure column. Alternatively, it is also possible to use a generator turbine and to eliminate supercharger 21 and aftercooler 22 (not shown).

Der dritte Teilstrom 30 wird von dem Zwischendruck aus in einem zweiten motorgetriebenen Nachverdichter 31 mit Nachkühler 32 auf einen hohen Druck von 60 bar gebracht, über Leitung 33 zum Hauptwärmetauscher 8 geführt und dort abgekühlt und (pseudo-)verflüssigt. Anschließend wird der dritte Teilstrom 33 in einem Entspannungsventil 34 auf etwa Hochdrucksäulendruck entspannt und über Leitung 35 in das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung eingeleitet, und zwar mindestens teilweise in flüssiger Form. Alternativ wird die Entspannung in einer Turbine 36 durchgeführt, die an einen Generator 37 gekoppelt ist. Ein Teil 38, 39 der Flüssigluft kann in einem Unterkühlungs-Gegenströmer 54 abgekühlt und der Niederdrucksäule 51 an einer geeigneten Zwischenstelle zugeführt werden.The third partial flow 30 is brought from the intermediate pressure in a second motor-driven booster 31 with aftercooler 32 to a high pressure of 60 bar, passed via line 33 to the main heat exchanger 8 and there cooled and (pseudo-) liquefied. Subsequently, the third partial stream 33 is expanded in an expansion valve 34 to about high pressure column pressure and introduced via line 35 in the distillation column system for nitrogen-oxygen separation, at least partially in liquid form. Alternatively, the relaxation is performed in a turbine 36 which is coupled to a generator 37. A portion 38, 39 of the liquid air may be cooled in a supercooling countercurrent 54 and supplied to the low pressure column 51 at a suitable intermediate point.

Der gasförmige Kopfstickstoff 55 der Hochdrucksäule 50 wird zu einem ersten Teil 56 im Hauptkondensator 53 verflüssigt. Ein erster Teil 58 des dabei erzeugten Flüssigstickstoffs 57 wird als Rücklauf auf die Hochdrucksäule 50 aufgegeben. Ein zweiter Teil 66, 67 wird im Unterkühlungs-Gegenströmer 54 abgekühlt und dem Kopf der Niederdrucksäule 51 als Rücklauf zugeführt.The gaseous top nitrogen 55 of the high-pressure column 50 is liquefied to a first part 56 in the main condenser 53. A first part 58 of the liquid nitrogen 57 produced in the process is fed as reflux to the high-pressure column 50. A second part 66, 67 is cooled in the subcooling countercurrent 54 and fed to the head of the low pressure column 51 as reflux.

Außerdem wird bei dem Ausführungsbeispiel eine stickstoffreiche Zwischenfraktion 68, 69 im Unterkühlungs-Gegenströmer 54 abgekühlt und der Niederdrucksäule 51 an einer Zwischenstelle zugespeist.In addition, in the embodiment, a nitrogen-rich intermediate fraction 68, 69 is cooled in the subcooling countercurrent 54 and fed to the low pressure column 51 at an intermediate point.

Die sauerstoffangereicherte Sumpffraktion 70 aus der Hochdrucksäule 50 wird ebenfalls im Unterkühlungs-Gegenströmer 54 abgekühlt und zu einem ersten Teil 71 der Niederdrucksäule 51 an einer anderen Zwischenstelle zugeleitet.The oxygen-enriched bottoms fraction 70 from the high-pressure column 50 is also cooled in the subcooling countercurrent 54 and fed to a first part 71 of the low-pressure column 51 at another intermediate point.

In dem Ausführungsbeispiel wird Druckstickstoffprodukt unter vier verschiedenen Drücken gewonnen.In the embodiment, pressurized nitrogen product is recovered under four different pressures.

Zum einen werden zwei Stickstoffproduktströme direkt gasförmig aus dem Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung abgezogen, und im Hauptwärmetauscher 8 auf etwa Umgebungstemperatur angewärmt, nämlich gasförmiger Kopfstickstoff 73, 74, 75 der Niederdrucksäule 51 als Druckstickstoffprodukt unter Niederdrucksäulendruck (GAN) und ein zweiter Teil 72, 76 des Kopfstickstoffs 55 der Hochdrucksäule als Druckstickstoffprodukt unter Hochdrucksäulendruck (PGAN1).First, two nitrogen product streams are withdrawn directly from the distillation column nitrogen-oxygen separation system in gas, and heated in the main heat exchanger 8 to about ambient temperature, namely gaseous overhead nitrogen 73, 74, 75 of the low pressure column 51 as low pressure column pressure (GAN) pressurized nitrogen product and a second Part 72, 76 of the top nitrogen 55 of the high pressure column as pressurized nitrogen product under high pressure column pressure (PGAN1).

Zum anderen wird ein dritter Teil 59 des Flüssigstickstoffs 57 aus dem Hauptkondensator 53 einer Stickstoff-Innenverdichtung zugeführt. Er wird in einerOn the other hand, a third part 59 of the liquid nitrogen 57 from the main condenser 53 is fed to a nitrogen internal compression. He will be in one

Stickstoffpumpe 60 in flüssigem Zustand auf einen erhöhten Stickstoffdruck oberhalb des Betriebsdrucks der Hochdrucksäule gebracht, über Leitung 61 zum Hauptwärmetauscher 8 geführt, dort in indirektem Wärmeaustausch mit Einsatzluft (pseudo-)verdampft und auf etwa Umgebungstemperatur angewärmt und schließlich unter dem erhöhten Druck über Leitung 62 als gasförmiges Druckstickstoffprodukt (ICGAN2) gewonnen. Ein Teil 63 des gepumpten Stickstoffs kann in einem Entspannungsventil 64 auf einen Zwischendruck zwischen dem Hochdrucksäulendruck und dem erhöhten Stickstoffdruck abgedrosselt und unter diesem Zwischendruck als weiteres gasförmiges Druckstickstoffprodukt 65 (ICGAN1) gewonnen werden.Nitrogen pump 60 brought in the liquid state to an increased nitrogen pressure above the operating pressure of the high pressure column, passed via line 61 to the main heat exchanger 8, there in indirect heat exchange with feed air (pseudo) evaporated and warmed to about ambient temperature and finally under the increased pressure via line 62 as gaseous pressure nitrogen product (ICGAN2) won. A portion 63 of the pumped nitrogen may be throttled in an expansion valve 64 to an intermediate pressure between the high pressure column pressure and the increased nitrogen pressure and recovered under this intermediate pressure as another gaseous pressure nitrogen product 65 (ICGAN1).

Ein Drucksauerstoffprodukt könnte durch gasförmige Entnahme unmittelbar oberhalb des Sumpfs der Niederdrucksäule 51 und anschließende Anwärmung im Hauptwärmetauscher unter etwa Niederdrucksäulendruck gewonnen und bei Bedarf in einem Sauerstoffverdichter weiter verdichtet (Außenverdichtung) werden. In der Regel günstiger ist es, auch hier eine Innenverdichtung anzuwenden, indem ein Sauerstoffstrom 77 in flüssigem Zustand aus dem unteren Bereich der Niederdrucksäule 51 entnommen wird, hier unmittelbar am Sumpf beziehungsweise aus dem Verdampfungsraum des Hauptkondensators 53. Der Sauerstoffstrom 77 wird in flüssigem Zustand einer Druckerhöhung auf einen erhöhten Sauerstoffdruck in einer Sauerstoffpumpe 78 unterzogen und im Hauptwärmetauscher 8 in indirektem Wärmeaustausch mit Einsatzluft verdampft oder pseudo-verdampft, wobei ein Teil der Einsatzluft verflüssigt oder pseudo-verflüssigt wird. Mindestens ein erster Teil 80, 81 des gepumpten Sauerstoffs 79 wird dabei als Drucksauerstoffprodukt (HP-GOX) unter dem erhöhten Sauerstoffdruck gewonnen. Ein anderer Teil 82, 84 des gepumpten Sauerstoffs 79 kann in einem Entspannungsventil 83 auf einen Zwischendruck zwischen dem Niederdrucksäulendruck und dem erhöhten Sauerstoffdruck abgedrosselt und unter diesem Zwischendruck als weiteres gasförmiges Drucksauerstoffprodukt (MP-GOX) gewonnen werden.A pressure oxygen product could be obtained by gaseous removal immediately above the bottom of the low pressure column 51 and then heating in the main heat exchanger at about low pressure column pressure and further compressed in an oxygen compressor if necessary (external compression). In general, it is more favorable here to apply an internal compression by taking an oxygen stream 77 in the liquid state from the lower region of the low-pressure column 51, here directly at the bottom or from the evaporation space of the main condenser 53. The oxygen flow 77 becomes a liquid state Pressure increase to an increased oxygen pressure in an oxygen pump 78 subjected and vaporized in the main heat exchanger 8 in indirect heat exchange with feed air or pseudo-vaporized, wherein a portion of the feed air is liquefied or pseudo-liquefied. At least a first part 80, 81 of the pumped oxygen 79 is thereby obtained as a pressure oxygen product (HP-GOX) under the increased oxygen pressure. Another part 82, 84 of the pumped oxygen 79 can be throttled in an expansion valve 83 to an intermediate pressure between the low-pressure column pressure and the increased oxygen pressure and recovered under this intermediate pressure as another gaseous pressure oxygen product (MP-GOX).

An einer Zwischenstelle der Niederdrucksäule 51 (der "ersten Zwischenstelle") wird der Niederdrucksäule ein gasförmiger Unreinstickstoffstrom 85 entnommen, der weniger rein als der Kopfstickstoff 73 ist, aber mindestens 80 % Stickstoff enthält. In dem Ausführungsbeispiel beträgt sein Stickstoffgehalt 90 %. Erfindungsgemäß wird dieser Strom zum Betrieb einer Restgassäule 52 verwendet, die einen Sumpfverdampfer 85 aufweist und unter einem Druck von 1,4 bar am Kopf betrieben wird. Der Unreinstickstoffstrom 85 wird in den Verflüssigungsraum des Sumpfverdampfers eingeleitet, dort in indirekten Wärmeaustausch mit der Sumpfflüssigkeit der Restgassäule 52 gebracht und dabei mindestens teilweise kondensiert. Der mindestens teilweise verflüssigte Unreinstickstoffstrom 87 wird in einem Drosselventil 88 auf den Betriebsdruck der Restgassäule entspannt und in den oberen Bereich der Restgassäule 52 eingeleitet, insbesondere unmittelbar am Kopf der Säule.At an intermediate point of the low-pressure column 51 (the "first intermediate point"), a gaseous impure nitrogen stream 85 is taken from the low-pressure column which is less pure than the top nitrogen 73 but contains at least 80% nitrogen. In the embodiment, its nitrogen content is 90%. According to the invention, this stream is used to operate a residual gas column 52, which has a bottom evaporator 85 and is operated at a pressure of 1.4 bar at the top. Of the Impurity stream 85 is introduced into the liquefaction space of the bottom evaporator where it is brought into indirect heat exchange with the bottom liquid of the residual gas column 52 and thereby at least partially condensed. The at least partially liquefied impure nitrogen stream 87 is expanded in a throttle valve 88 to the operating pressure of the residual gas column and introduced into the upper region of the residual gas column 52, in particular directly at the top of the column.

In der Restgassäule wird eine flüssige Rohsauerstofffraktion 89 aus der Hochdrucksäule 50 weiter angereichert. Sie wird durch einen Teil der Sumpffraktion 70 gebildet, aus der sie stromabwärts des Unterkühlungs-Gegenströmers 54 abgezweigt wird. Die flüssige Rohsauerstofffraktion 89 wird in einem Entspannungsventil 90 entspannt und der Restgassäule 52 an einer ersten Zwischenstelle zugeführt.In the residual gas column, a crude liquid oxygen fraction 89 from the high-pressure column 50 is further enriched. It is formed by a portion of the bottom fraction 70, from which it is branched downstream of the subcooling countercurrent 54. The liquid crude oxygen fraction 89 is expanded in an expansion valve 90 and fed to the residual gas column 52 at a first intermediate point.

In dem Ausführungsbeispiel wird der Restgassäule außerdem an einer zweiten Zwischenstelle ein Teilstrom 90 der Flüssigluft 38 nach ihrer Abkühlung im Unterkühlungs-Gegenströmer 54 zugespeist.In the embodiment, the residual gas column is also fed at a second intermediate point, a partial flow 90 of the liquid air 38 after cooling in the subcooling countercurrent 54.

Die flüssige Sumpffraktion 91 der Restgassäule ist stärker an Sauerstoff angereichert als die Rohsauerstofffraktion 89 aus der Hochdrucksäule 50 und wird mittels einer Pumpe 92 über auf den höheren Druck der Niederdrucksäule 51 gebracht. Sie wird der Niederdrucksäule über Leitung 93 an einer zweiten Zwischenstelle zugeleitet, die unterhalb der ersten Zwischenstelle liegt, an welcher der Unreinstickstoffstrom 85 abgezogen wird. Die zweite Zwischenstelle liegt auch unterhalb der Einspeisestelle des Rohsauerstoffs 71, der direkt aus der Hochdrucksäule 50 in die Niederdrucksäule 51 geleitet wird.The liquid bottoms fraction 91 of the residual gas column is enriched more strongly with oxygen than the crude oxygen fraction 89 from the high-pressure column 50 and is brought by means of a pump 92 over to the higher pressure of the low-pressure column 51. It is supplied to the low-pressure column via line 93 at a second intermediate point, which is below the first intermediate point at which the impure nitrogen stream 85 is withdrawn. The second intermediate point is also below the feed point of the crude oxygen 71, which is passed directly from the high pressure column 50 in the low pressure column 51.

Am Kopf der Restgassäule 52 wird ein stickstoffreicher Reststrom 94, 95, 96 gasförmig abgezogen und im Unterkühlungs-Gegenströmer 54 und im. Hauptwärmetauscher 8 angewärmt. Das warme Restgas 96 kann bei Bedarf noch als Regeneriergas für die Reinigungseinheit 5 und/oder in einem Verdunstungskühler der Vorkühleinheit 4 eingesetzt werden.At the top of the residual gas column 52, a nitrogen-rich residual stream 94, 95, 96 is withdrawn in gaseous form and in the subcooling countercurrent 54 and in. Main heat exchanger 8 warmed up. If desired, the warm residual gas 96 can still be used as a regeneration gas for the purification unit 5 and / or in an evaporative cooler of the precooling unit 4.

Figur 2 unterscheidet sich von Figur 1 dadurch, dass der Prozess außerdem eine Mitteldrucksäule 200 verwendet, wie sie aus Drei-Säulen-Systemen bekannt ist. Die Mitteldrucksäule 200 weist je einen Kondensator-Verdampfer als Sumpfverdampfer 201 und Kopfkondensator 202 auf und wird unter einem Druck betrieben, der zwischen den Betriebsdrücken von Niederdrucksäule und Hochdrucksäule liegt, in dem Beispiel bei 6 bar. Ein Teil 201 der Sumpffraktion 70 der Hochdrucksäule 50 wird der Mitteldrucksäule 200 als Einsatz zugeleitet. Zusätzlich kann ein Teil 204 der Flüssigluft 38 in die Mitteldrucksäule 200 eingespeist werden. FIG. 2 differs from FIG. 1 in that the process also uses a medium pressure column 200 known from three column systems. The medium-pressure column 200 each has a condenser-evaporator as a bottom evaporator 201 and top condenser 202 and is operated under a pressure which is between the operating pressures of low pressure column and high pressure column, in the example at 6 bar. A portion 201 of the sump fraction 70 of the high-pressure column 50 is fed to the medium-pressure column 200 as an insert. In addition, a portion 204 of the liquid air 38 can be fed into the medium-pressure column 200.

Die Sumpfflüssigkeit 205 der Mitteldrucksäule 200 wird im Kopfkondensator 202 der Mitteldrucksäule 200 teilweise verdampft und anschließend über die Leitungen 206 beziehungsweise 207 an geeigneter Stelle in die Niederdrucksäule 51 eingespeist. Der gasförmige Kopfstickstoff der Mitteldrucksäule 200 wird, soweit er nicht im Kopfkondensator 202 kondensiert wird, über Leitung 208 zum Hauptwärmetauscher 8 geführt und über Leitung 209 als weiteres Druckstickstoffprodukt unter Mitteldrucksäulendruck (PGAN2) gewonnen.The bottom liquid 205 of the medium-pressure column 200 is partially evaporated in the top condenser 202 of the medium-pressure column 200 and then fed via the lines 206 and 207 at a suitable point in the low-pressure column 51. The gaseous top nitrogen of the medium-pressure column 200 is, as far as it is not condensed in the top condenser 202, passed via line 208 to the main heat exchanger 8 and recovered via line 209 as a further pressure nitrogen product under medium pressure column pressure (PGAN2).

In Figur 2 wird die gepumpte Sumpffraktion 293 aus der Restgassäule 52 ausschließlich in die Mitteldrucksäule 200 eingespeist.In FIG. 2 the pumped bottoms fraction 293 from the residual gas column 52 is fed exclusively into the medium-pressure column 200.

Alternativ dazu kann diese Fraktion analog zu Figur 1 (Leitung 93) ausschließlich oder teilweise in die Niederdrucksäule 51 eingespeist werden. Die Einspeisung in die Niederdrucksäule 51 findet vorzugsweise auf derselben Höhe wie die Zuspeisung der flüssig verbliebenen Fraktion 207 aus dem Verdampfungsraum des Kopfkondensators 202 der Mitteldrucksäule statt.Alternatively, this fraction can be analogous to FIG. 1 (Line 93) are fed exclusively or partially into the low-pressure column 51. The feed into the low-pressure column 51 preferably takes place at the same level as the feed of the liquid fraction 207 remaining from the evaporation space of the top condenser 202 of the medium-pressure column.

Claims (9)

Verfahren zur Gewinnung von Druckstickstoff und Drucksauerstoff durch Tieftemperaturzerlegung von Luft, bei dem - verdichtete und gereinigte Einsatzluft (6, 10, 23, 33) in einem Hauptwärmetauscher (8) abgekühlt und in ein Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung eingeleitet wird, das mindestens eine Hochdrucksäule (50) und eine Niederdrucksäule (51) aufweist, wobei die Niederdrucksäule (51) unter einem Druck betrieben wird, der mindestens 2 bar beträgt, - mindestens ein Stickstoffstrom (73, 74) aus dem oberen Bereich der Niederdrucksäule entnommen, im Hauptwärmetauscher (8) angewärmt und als Druckstickstoffprodukt (75) gewonnen wird, - mindestens ein Sauerstoffstrom (77) aus dem unteren Bereich der Niederdrucksäule (51) entnommen, im Hauptwärmetauscher (8) angewärmt und als Drucksauerstoffprodukt (81, 84) gewonnen wird, - ein Unreinstickstoffstrom (85) gasförmig von einer ersten Zwischenstelle der Niederdrucksäule (51) entnommen wird, die unterhalb der Stelle liegt, an welcher der Stickstoffstrom (73) entnommen wird,
dadurch gekennzeichnet, dass - das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung außerdem eine Restgassäule (52) enthält, deren Betriebsdruck niedriger als der Betriebsdruck der Niederdrucksäule (51) ist, - die Restgassäule (52) einen Sumpfverdampfer (86) aufweist, der als Kondensator-Verdampfer ausgebildet ist, - eine flüssige Rohsauerstofffraktion (89), insbesondere aus der Hochdrucksäule (50), entspannt und der Restgassäule (52) an einer ersten Zwischenstelle zugeleitet wird, - der gasförmige Unreinstickstoffstrom (85) in den Verflüssigungsraum des Sumpfverdampfers (86) eingeleitet und dort mindestens teilweise verflüssigt wird, - der mindestens teilweise verflüssigte Unreinstickstoffstrom (87) entspannt (88) und in den oberen Bereich der Restgassäule (52) eingeleitet wird. Process for the production of pressure nitrogen and pressure oxygen by cryogenic separation of air, in which - compressed and purified feed air (6, 10, 23, 33) is cooled in a main heat exchanger (8) and introduced into a distillation column system for nitrogen-oxygen separation having at least one high pressure column (50) and a low pressure column (51) in which the low-pressure column (51) is operated under a pressure which is at least 2 bar, - At least one nitrogen stream (73, 74) taken from the upper region of the low-pressure column, heated in the main heat exchanger (8) and recovered as pressurized nitrogen product (75), - At least one oxygen stream (77) taken from the lower region of the low pressure column (51), heated in the main heat exchanger (8) and is obtained as a pressure oxygen product (81, 84), - an impure nitrogen stream (85) is taken in gaseous form from a first intermediate point of the low-pressure column (51) which lies below the point at which the nitrogen stream (73) is withdrawn,
characterized in that the distillation column system for nitrogen-oxygen separation also contains a residual gas column (52) whose operating pressure is lower than the operating pressure of the low-pressure column (51), - The residual gas column (52) has a sump evaporator (86) which is designed as a condenser-evaporator, a liquid crude oxygen fraction (89), in particular from the high-pressure column (50), is expanded and fed to the residual gas column (52) at a first intermediate point, - The gaseous impure nitrogen stream (85) is introduced into the liquefaction space of the bottom evaporator (86) and is at least partially liquefied there, - The at least partially liquefied non-nitrogen stream (87) is expanded (88) and introduced into the upper region of the residual gas column (52). Verfahren nach Anspruch 1, dadurch gekennzeichnet, dass eine flüssige Sumpffraktion (91, 93) aus der Restgassäule (52) entnommen und der Niederdrucksäule (51) an einer zweiten Zwischenstelle zugeleitet wird, die unterhalb der ersten Zwischenstelle liegt.A method according to claim 1, characterized in that a liquid sump fraction (91, 93) removed from the residual gas column (52) and the low pressure column (51) is fed to a second intermediate point, which is below the first intermediate point. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass vom Kopf der Restgassäule (52) ein gasförmiger Reststrom abgezogen und im Hauptwärmetauscher (8) angewärmt wird.A method according to claim 1 or 2, characterized in that deducted from the head of the residual gas column (52), a gaseous residual stream and in the main heat exchanger (8) is heated. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass im Unreinstickstoffstrom (85) zwischen Niederdrucksäule (51) und Sumpfverdampfer (86) keine Druckerhöhung vorgenommen wird und insbesondere der Verflüssigungsraum des Sumpfverdampfers (86) im Wesentlichen unter dem Betriebsdruck der Niederdrucksäule (52) betrieben wird.Method according to one of claims 1 to 3, characterized in that no increase in pressure is carried out in the impure nitrogen stream (85) between the low-pressure column (51) and the bottom evaporator (86) and in particular the liquefaction space of the bottom evaporator (86) substantially below the operating pressure of the low-pressure column (52 ) is operated. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass ein Sauerstoffstrom (77) in flüssigem Zustand aus dem unteren Bereich der Niederdrucksäule (52) entnommen, in flüssigem Zustand einer Druckerhöhung (78) unterzogen und im Hauptwärmetauscher (8) in indirektem Wärmeaustausch mit Einsatzluft (10, 33) verdampft oder pseudo-verdampft wird, wobei ein Teil (33) der Einsatzluft verflüssigt oder pseudo-verflüssigt wird.Method according to one of claims 1 to 4, characterized in that an oxygen stream (77) taken in the liquid state from the lower region of the low pressure column (52) in the liquid state of a pressure increase (78) subjected and in the main heat exchanger (8) in indirect heat exchange is vaporized or pseudo-vaporized with feed air (10, 33), wherein a portion (33) of the feed air is liquefied or pseudo-liquefied. Verfahren nach Anspruch 5, dadurch gekennzeichnet, dass mindestens ein Teil (90) der (pseudo-)verflüssigten Einsatzluft (33, 35) der Restgassäule (52) an einer zweiten Zwischenstelle zugeleitet wird, die oberhalb der ersten Zwischenstelle liegt.A method according to claim 5, characterized in that at least a part (90) of the (pseudo) liquefied feed air (33, 35) of the residual gas column (52) is fed to a second intermediate point, which is above the first intermediate point. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Restgassäule (52) keinen Kopfkondensator aufweist.Method according to one of claims 1 to 6, characterized in that the residual gas column (52) has no top condenser. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass die Niederdrucksäule (51) keinen Kopfkondensator aufweist.Method according to one of claims 1 to 6, characterized in that the low-pressure column (51) has no top condenser. Vorrichtung zur Gewinnung von Druckstickstoff und Drucksauerstoff durch Tieftemperaturzerlegung von Luft - mit einem Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung, das mindestens eine Hochdrucksäule (50) und eine Niederdrucksäule (51) aufweist, - mit einem Hauptwärmetauscher (8) zum Abkühlen verdichteter und gereinigter Einsatzluft (6, 10, 23, 33), - mit Mitteln zum Einleiten abgekühlter Einsatzluft (12, 35) in das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung, - mit einer Regeleinrichtung zur Steuerung des Betriebsdrucks der Niederdrucksäule (51) auf einen Wert, der mindestens 2 bar beträgt, - mit Mitteln zum Entnehmen eines Stickstoffstroms (73, 74) aus dem oberen Bereich der Niederdrucksäule, - mit Mitteln zum Einleiten des Stickstoffstroms (74) in den Hauptwärmetauscher (8) zwecks Anwärmung, - mit Mitteln zum Abziehen des angewärmten Stickstoffstroms als Druckstickstoffprodukt (75), - mit Mitteln zum Entnehmen eines Sauerstoffstroms (77) aus dem unteren Bereich der Niederdrucksäule (51), im Hauptwärmetauscher (8) angewärmt und als Drucksauerstoffprodukt (81, 84) gewonnen wird, - mit Mitteln zum Einleiten des Unreinstickstoffstroms (85) gasförmig von einer ersten Zwischenstelle der Niederdrucksäule (51) entnommen wird, die unterhalb der Stelle liegt, an welcher der Stickstoffstrom (73) entnommen wird, dadurch gekennzeichnet, dass - das Destilliersäulen-System zur Stickstoff-Sauerstoff-Trennung außerdem eine Restgassäule (52) enthält, deren Betriebsdruck niedriger als der Betriebsdruck der Niederdrucksäule (51) ist, - die Restgassäule (52) einen Sumpfverdampfer (86) aufweist, der als Kondensator-Verdampfer ausgebildet ist
und die Vorrichtung außerdem - Mittel zum Entspannen einer flüssigen Rohsauerstofffraktion (89), insbesondere aus der Hochdrucksäule (50), - Mittel zum Einleiten der entspannten Rohsauerstofffraktion (89) in die Restgassäule (52) an einer ersten Zwischenstelle, - Mittel zu Einleiten des gasförmigen Unreinstickstoffstroms (85) in den Verflüssigungsraum des Sumpfverdampfers (86) zwecks dessen mindestens partiellen Verflüssigung, - Mittel (88) zum Entspannen des mindestens teilweise verflüssigten Unreinstickstoffstroms (87) entspannt (88) und - Mittel zum Einleiten des entspannten Unreinstickstoffstroms in den oberen Bereich der Restgassäule (52)
aufweist. Apparatus for recovering pressure nitrogen and pressure oxygen by cryogenic separation of air with a distillation column system for nitrogen-oxygen separation, which has at least one high-pressure column (50) and one low-pressure column (51), with a main heat exchanger (8) for cooling compressed and purified feed air (6, 10, 23, 33), with means for introducing cooled feed air (12, 35) into the distillation column system for nitrogen-oxygen separation, - With a control device for controlling the operating pressure of the low-pressure column (51) to a value which is at least 2 bar, with means for removing a stream of nitrogen (73, 74) from the upper region of the low-pressure column, with means for introducing the nitrogen stream (74) into the main heat exchanger (8) for heating, with means for removing the warmed nitrogen stream as pressurized nitrogen product (75), heated with means for removing an oxygen stream (77) from the lower region of the low-pressure column (51), in the main heat exchanger (8) and recovered as a pressure oxygen product (81, 84), - is taken with gaseous from a first intermediate point of the low pressure column (51) with means for introducing the impure nitrogen stream (85), which is below the point at which the nitrogen stream (73) is removed, characterized in that the distillation column system for nitrogen-oxygen separation also contains a residual gas column (52) whose operating pressure is lower than the operating pressure of the low-pressure column (51), - The residual gas column (52) has a sump evaporator (86), which is designed as a condenser-evaporator
and the device as well Means for expanding a crude liquid oxygen fraction (89), in particular from the high-pressure column (50), Means for introducing the expanded crude oxygen fraction (89) into the residual gas column (52) at a first intermediate point, - means for introducing the gaseous impure nitrogen stream (85) into the liquefaction space of the bottom evaporator (86) for the purpose of at least partial liquefaction thereof, - Relaxing means (88) for relaxing the at least partially liquefied unreactive nitrogen stream (87) (88) and - Means for introducing the relaxed impure nitrogen stream in the upper region of the residual gas column (52)
having.
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