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EP3724573A1 - Method and apparatus for the cryogenic separation of a synthesis gas containing a nitrogen separation step - Google Patents

Method and apparatus for the cryogenic separation of a synthesis gas containing a nitrogen separation step

Info

Publication number
EP3724573A1
EP3724573A1 EP18833939.4A EP18833939A EP3724573A1 EP 3724573 A1 EP3724573 A1 EP 3724573A1 EP 18833939 A EP18833939 A EP 18833939A EP 3724573 A1 EP3724573 A1 EP 3724573A1
Authority
EP
European Patent Office
Prior art keywords
column
nitrogen
liquid
condenser
carbon monoxide
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.)
Pending
Application number
EP18833939.4A
Other languages
German (de)
French (fr)
Inventor
Antoine Hernandez
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 Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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 Liquide SA, LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude filed Critical Air Liquide SA
Publication of EP3724573A1 publication Critical patent/EP3724573A1/en
Pending legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—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
    • F25J3/0223—H2/CO mixtures, i.e. synthesis gas; Water gas or shifted synthesis 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
    • F25J3/0252—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 hydrogen
    • 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
    • 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
    • F25J3/0261—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 carbon monoxide
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/40—Features relating to the provision of boil-up in the bottom of a column
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/70—Refluxing the column with a condensed part of the feed stream, i.e. fractionator top is stripped or self-rectified
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/72—Refluxing the column with at least a part of the totally condensed overhead 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
    • F25J2200/00—Processes or apparatus using separation by rectification
    • F25J2200/74—Refluxing the column with at least a part of the partially condensed overhead 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
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/02—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum
    • F25J2205/04—Processes or apparatus using other separation and/or other processing means using simple phase separation in a vessel or drum in the feed line, i.e. upstream of the fractionation step
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2210/00—Processes characterised by the type or other details of the feed stream
    • F25J2210/42—Nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/02—Bath type boiler-condenser using thermo-siphon effect, e.g. with natural or forced circulation or pool boiling, i.e. core-in-kettle heat exchanger
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2250/00—Details related to the use of reboiler-condensers
    • F25J2250/04—Down-flowing type boiler-condenser, i.e. with evaporation of a falling liquid film
    • 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
    • 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
    • F25J2270/12—External refrigeration with liquid vaporising 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
    • 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
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/902—Details about the refrigeration cycle used, e.g. composition of refrigerant, arrangement of compressors or cascade, make up sources, use of reflux exchangers etc.
    • 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
    • F25J2270/90—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration
    • F25J2270/904—External refrigeration, e.g. conventional closed-loop mechanical refrigeration unit using Freon or NH3, unspecified external refrigeration by liquid or gaseous cryogen in an open loop

Definitions

  • the present invention relates to a method and an apparatus for cryogenic separation of a synthesis gas containing nitrogen.
  • this gas contains carbon monoxide, hydrogen, methane and nitrogen. It preferably contains less than 50 mol% of methane. It preferably contains more than 10 mol% of carbon monoxide.
  • the production units for carbon monoxide and hydrogen can be separated into two parts:
  • the cold box process is partial condensation.
  • the synthesis gas is contaminated with methane, for example for the MEG, TDI / MDI or PC applications, it is necessary to include a CH 4 separation column in the cold box.
  • the synthesis gas is contaminated with nitrogen, for example if nitrogen is used to transport the coal, it is necessary to include a nitrogen separation column in the cold box.
  • a CO / N2 column is positioned upstream of a CO / CH 4 column. The reboiling of the CO / CH 4 column is ensured by condensation of the ring nitrogen. Condensation at the top of column CO / N 2 is provided by vaporization of liquid N2 of the low pressure cycle.
  • the vaporized nitrogen in the condensers of the CO / N 2 and CO / CH 4 columns returns to the compressor suction of the nitrogen cycle.
  • the CO / N column 2 operates at a relatively low pressure (2.6 bar).
  • the pressure of the CO / CH 4 column is relatively low.
  • the condensation of the top of the CO / N2 column is ensured by vaporization of the tank of the CO / CH 4 column and in addition by heating the hydrogen-rich fraction of the partial condensing pot of the synthesis gas.
  • the product CO at the outlet of the column CO / N2 returns to the suction of the compressor CO to be compressed to the required pressure.
  • the top condenser of the CO / N2 column has a large volume because the complement is provided by heating the hydrogen, so a large gas flow: as this exchanger must be positioned in height relative to the head of the column CO / N2, its large volume would make it difficult to transport the package containing the column CO / N2.
  • the CO / N2 condenser coupling and CO / CH 4 reboiler makes the operation of the unit difficult when the CH 4 and N 2 contents in the incoming synthesis gas vary.
  • DE2814600 describes a separation process using a methane removal column, followed by a double column whose head of the CO / argon separation column heats the tank of the denitrogenation column.
  • the denitrogen head condenser vaporizes the liquid from the tank of the denitrogenation column after expansion and vaporization of a nitrogen cycle liquid.
  • the nitrogen cycle is not used as a cooling fluid to condense the separation head of a separation column CH4, or in the column of 28 nor in the column 13.
  • the CH4 13 separation column head is cooled by hydrogen. This leads to a larger exchanger 13 at the top of the column which takes up more space in the package of the cold box and is therefore more difficult to transport.
  • the cold supply is not sufficient and CH4 remains in the fluid sent to the second column whereas according to the invention, a single column removes all the CH4.
  • DE2814860 has a N2 circuit to the argon / CO column vessel scrubber which is also at a higher pressure than that of the present invention where the CO / CH4 column is reboiled by the synthesis gas.
  • the reboiling of the CO / N2 separation is provided by the N2 cycle via the tank refluxer of the argon / CO column, which requires a higher pressure than that according to the invention, where it is necessary to nitrogen reboiling only at the pressure of the column CO / N2.
  • a method for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and optionally methane in which:
  • the hydrogen-depleted fluid is sent to a denitrogenation column having a head condenser and a bottom reboiler to produce a nitrogen-enriched gas at the top of the column and a column-depleted nitrogen-depleted liquid.
  • a denitrogenation column having a head condenser and a bottom reboiler to produce a nitrogen-enriched gas at the top of the column and a column-depleted nitrogen-depleted liquid.
  • Cooling the condenser of the denitrogenation column by means of a nitrogen cycle using a nitrogen compressor with at least a first stage and a second stage, the inlet pressure of the first stage being lower than that of the second stage ,
  • the reactor liquid is expanded from the denitrogenation column and sent to the head condenser of the denitrogenation column to vaporize at least partially by heat exchange in a condenser heat exchanger with the enriched gas. nitrogen which is condensed, and
  • the condenser is also vaporized in the liquid nitrogen condenser from the nitrogen cycle and vaporized nitrogen is returned in the heat exchanger at the inlet of the second stage of the nitrogen compressor and
  • the bottom liquid of the denitrogenation column is sent to a carbon monoxide and methane separation column comprising a head condenser which is a bath vaporizer placed in a liquid bath or
  • the separation of step ii) comprises a distillation step in a carbon monoxide and methane separation column for separating a methane-depleted flow rate from a methane-enriched flow rate and at least a part of the depleted flow rate; methane is the hydrogen-depleted fluid feeding the denitrogenation column, the carbon monoxide and methane separation column comprising a head condenser which is a bath vaporizer placed in a liquid bath the liquid bath of a) or b ) being fed with liquid nitrogen from the nitrogen cycle.
  • the mixture contains methane.
  • the separation of step ii) comprises a distillation step in a carbon monoxide and methane separation column for separating a methane depleted flow from a methane enriched flow and at least a portion of the methane depleted flow is the fluid depleted of hydrogen supplying the denitrogenation column.
  • the reactor liquid is sent from the denitrogenation column to a separation column of carbon monoxide and methane.
  • the carbon monoxide and methane separation column comprises a head condenser which is a bath vaporizer placed in a liquid bath.
  • the top condenser of the carbon monoxide and methane separation column is fed with liquid nitrogen from the nitrogen cycle.
  • liquid nitrogen from the top condenser of the carbon monoxide and methane separation column is vaporized in the overhead condenser of the denitrogenation column.
  • the cooled mixture is separated in the heat exchanger by at least one partial condensation step in order to form a hydrogen-depleted gas
  • the hydrogen-depleted gas is sent to an intermediate level of a depletion column having a reboiler. tank and is sent from the bottom liquid of the depletion column to a denitrogenation column according to the case a) or to the separation column of carbon monoxide and methane as the case b).
  • the reboiler of the exhaustion column and / or the reboiler of the carbon monoxide and methane separation column are heated with at least part of the gaseous mixture.
  • the operating pressure of the denitrogenation column is at least 7 bar abs, or even 8 bar abs
  • the operating pressure of the separation column of carbon monoxide and methane is at least 5 bar abs, or even 6 bar abs.
  • the top condenser of the CO / CH4 column is cooled only with cycle nitrogen.
  • the reboiler of the denitrogenation column is heated by means of the cycle nitrogen.
  • the nitrogen used to heat the reboiler of the denitrogenation column is at the maximum pressure of the nitrogen cycle.
  • the nitrogen sent to the condenser bath of the CO / CH4 column is condensed at the maximum pressure of the nitrogen cycle.
  • an apparatus for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and optionally methane comprising a heat exchanger for cooling the mixture, means for separating the cooled mixture in the heat exchanger by at least one partial condensation and / or distillation and / or washing step in order to form a hydrogen-depleted fluid containing carbon monoxide and nitrogen, a denitrogenation column having a head condenser and optionally a bottom reboiler, a conduit for delivering the depleted fluid to hydrogen to the denitrogenation column to produce a nitrogen enriched gas at the column head and a column depleted nitrogen liquid, a nitrogen cycle using a nitrogen compressor to at least a first stage and a second stage , the inlet pressure of the first stage being lower than that of the second stage, means for sending liquid from the nitrogen cycle to the condenser of the denitrogenation column, means for expanding the bottom liquid of the column denitrogenation means for sending the expanded liquid to the
  • the apparatus also comprising means for supplying liquid nitrogen from the nitrogen cycle to the overhead condenser of the carbon monoxide and methane separation column.
  • the apparatus may include means for supplying liquid nitrogen from the overhead condenser of the carbon monoxide and methane separation column to the overhead condenser of the denitrogenation column.
  • the apparatus may comprise at least one phase separator for separating the cooled mixture into the heat exchanger by a partial condensation step to form a hydrogen-depleted gas, a depletion column and means for delivering the depleted gas. in hydrogen at an intermediate level of the exhaustion column.
  • the reboiling of the CO / CHU column is by cooling the synthesis gas while it is by condensation of the cycle in the DEXX: in our scheme this has the advantage of being able to increase the pressure of the CO / CH column. 4 without increasing the output pressure of compressor N2.
  • the condenser of the column head CO / N 2 is cooled by vaporization of at least a portion of the bottom liquid of the column CO / N2 after expansion and by vaporization of liquid IM2 at medium pressure.
  • the cooling is carried out by vaporization of liquid N2 of the low-pressure cycle. Spraying the vessel liquid after expansion makes it possible to considerably reduce the N 2 cycle flow rate to be vaporized in the condenser, which reduces the N 2 cycle flow rate and therefore the power of the N 2 cycle compressor.
  • the nitrogen flow rate is relatively large compared to the rate of CO produced.
  • the vaporized nitrogen in the condensers of the columns CG / IM2 and CO / CH 4 returns to an inter-stage compressor N 2 while in the prior art it returns to the suction of the compressor.
  • the prior art therefore leads to increase the compression energy of the cycle.
  • the flow 54 returns to the same pressure (2.4 bar) as the flow rate 2 necessary for the cooling of the synthesis gas in the E2 whereas in our diagram the flow rate of N2 vaporized in the condensers returns to the compressor 2 at a higher pressure than the flow rate of N2 necessary for cooling the synthesis gas.
  • the CO / N2 column is operated at a higher pressure (at least 7 bar, for example at 8.5 bar) compared to the prior art (2.6 bar).
  • FIG. 3 of DE102012020469 includes a pump to increase the pressure of the CO / CH4 column, but it remains low (3.8 bar) compared to the schemes according to the invention (at least 5 bar, or even at least 6 bar) and including in figure 3, the liquid N2 of the condenser of the column CO / CH4 is at low pressure and returns to the suction of the compressor whereas in our diagram the nitrogen of the condenser of head of column CO / CH4 returns to an inter-stage compressor N2 (at a higher pressure than the nitrogen that serves to cool the synthesis gas in the main exchanger).
  • the column CO / N 2 is at higher pressure, this allows to produce CO directly without recompression.
  • the condensation energy of the head of the CO / N2 column is provided by vaporization of the bottom liquid after expansion and addition by vaporization of low-pressure nitrogen of the N 2 ring. This reduces the size of the overhead condenser and makes the package containing the CO / N2 column and its overhead condenser transportable.
  • a gaseous mixture for example from a gasification of coal, contains carbon monoxide, hydrogen, methane, water and nitrogen.
  • the gas 1 is purified in adsorbent beds 3A, 3B and cooled in a cooler 4. Then it is sent to a first heat exchanger E1 to be cooled. Partial flow rates of the synthesis gas are used to heat the R1, R2 heaters drawn twice at different locations of the drawing for reasons of clarity. After expansion in a valve, it is separated in a phase separator S1 forming a gas 5 and a liquid 7.
  • the gas 5 is cooled in a heat exchanger E2, expanded, sent to a phase separator S4.
  • the gas 9 of this phase separator S4, rich in hydrogen, is heated in the heat exchangers E2, E1 and part of the gas serves to regenerate the adsorbent beds 3A, 3B.
  • Part 1 1 of the liquid of the phase separator S4 is expanded and sent to the top of a depletion column K1 operating at 17.6 bar.
  • Column K1 has no overhead condenser but has a reboiler R1.
  • the remainder 13 of the liquid of the phase separator S4 is expanded and sent to a phase separator S3.
  • the overhead gas 17 of the column K1 is heated in the exchangers E1, E2.
  • the liquid 7 of the phase separator S1 mixes with other fluids (separator head gas S3, derived from the liquid 13 from the separator S4) to form the flow 8 which is sent to a phase separator S2 and then to a intermediate level of the K1 exhaustion column.
  • the gas of the phase separator S3 and the liquid of the phase separator S3 after vaporization in the exchanger E2 are mixed with the fluid 7 to feed the column K1.
  • Bottle liquid 19 from column K1 is taken at -154 ° C, slackened to 8.3 bar, sent to the S5 phase separator and the gas and liquid from the phase separator are sent to an intermediate level of the CO column.
  • N2 K2 operating at 8.3 bars.
  • the column K2 has a head condenser C1, consisting of a plate heat exchanger, and a reboiler R2.
  • the overhead gas 27 of the column K2 partially condenses in the condenser C1, the formed liquid L, 29 being returned to the top of the column K2 and in part and the remaining gas V, enriched in nitrogen, being heated in the exchangers E2, E1 as a gas 31.
  • a liquid 53 from the top condenser C2 of the column K3 vaporizes by heat exchange with the gas 27 in the condenser C1 forming the gas 55 sent to the inlet of the compressor V3.
  • the tank liquor 33 enriched in carbon monoxide and depleted of nitrogen is divided in two 21, 35 and expanded.
  • a relaxed portion 21 to 6.5 bar is sent to a phase separator whose liquid is used in part to cool the condenser C1.
  • the condenser of the column head CO / N2 K2 K2 is cooled by vaporization of at least a portion of the tank liquid 33 of the column CO / N2 K2 after expansion and vaporization of the liquid nitrogen 53 at medium pressure.
  • Spraying the tank liquid 33 after expansion considerably reduces the nitrogen cycle flow rate to be vaporized in the condenser C1, which reduces the nitrogen cycle flow rate and therefore the power of the nitrogen cycle compressor.
  • Column K3 has a head condenser C2, consisting of a plate heat exchanger disposed in a bath of liquid to be vaporized, and a reboiler R3.
  • the carbon monoxide enriched head gas condenses in the condenser C2 and the methane-rich bottom liquid 39 is expanded and heated in the E1 exchanger.
  • Column K3 operates at 6.6 bars.
  • the plate heat exchanger is surrounded by an annular barrier forming an overflow wall P.
  • the liquid surrounding the heat exchanger can pass over the barrier P to be withdrawn as liquids 43, 53.
  • the head condenser C2 of the column K3 is cooled by compressed and expanded nitrogen 59 from the nitrogen cycle compressor V1, V2, V3 after cooling in the exchangers E1, E2.
  • the vaporized nitrogen is returned upstream of the last stage V3 of the nitrogen cycle compressor.
  • Nitrogen at the outlet pressure of stage V3 also serves to reboil reboiler R2 of column K2.
  • the reboilers R1 and R3 of the columns K1 and K3 are reheated by partial flow rates of the feed 1 downstream of the exchanger E1 and upstream of the phase separator S1.
  • This reboiling of the CO / CH 4 K 3 column by cooling the synthesis gas has the advantage of being able to increase the pressure of the CO / CH 4 column without increasing the output pressure of the nitrogen cycle compressor.
  • the partial flows sent to the reboiler R1, R3 are at the same temperature and the same pressure.
  • Liquid nitrogen 53 from the tank of the condenser C2 of the column K3 is sent to vaporize in the condenser C1 of the column K3 and then is returned downstream of the stage V2 and upstream of the stage V3.
  • the nitrogen vaporized in the condensers Ci, C3 of the columns CO / N2 K2 and CO / CH4 K3 returns to an interstage of the nitrogen compressor V1, V2.
  • the flow rate of N2 57 vaporized in the condensers Ci, C2 returns compressor N2 at a higher pressure than the flow rate of N2 necessary for cooling the synthesis gas. In our case this is made possible because the column CO / N2 K2 is operated at a higher pressure (8.5 bar) compared to the prior art (2.6 bar).
  • a gas 41 rich in carbon monoxide leaves column K3 at 6.6 bars at -170.4 ° C and heats up in heat exchangers E1, E2.
  • no carbon monoxide compressor is used. It is a product of the process and has not been compressed.
  • a supply of liquid nitrogen 69 makes it possible to compensate for leaks in the nitrogen cycle.
  • the liquid formed vaporizes in the exchanger E2 mixes with the gas of the separator S7 and is sent to the inlet of the compressor V1.
  • a portion 47 of the liquid nitrogen of the condenser C2 is expanded, sent to the separator S7 and the formed gas 49 enters the inlet of the compressor V1.
  • Another part 45 of the same liquid is expanded to a lower pressure and sent to the output of the compressor V1 and the input of the compressor V2.
  • the operating pressure of the denitrogenation column K2 is at least 7 bar abs, or even 8 bar abs; the operating pressure of the separation column of carbon monoxide and methane K3 is at least 5 bar abs, or even 6 bar abs.
  • the order of the separation columns of methane and carbon monoxide and denitrogenation is reversed.
  • liquid 19 of the tank of the exhaust column is sent, not to the deaerator column, but to an intermediate point of the CO / CH 4 K 3 separation column after separation of a SS phase separator.
  • the column CO / CH 4 K3 has a feed-heated reactor vessel R3 and a head condenser C2 which serves to condense the overhead gas 51 which is returned to column K3 in condensed form.
  • the condenser is cooled with condensed nitrogen 61, 63 produced by condensing the ring nitrogen 59 from the compressor V3 into the exchangers E1, E2 and the reboiler R2.
  • the liquid is partially vaporized producing a gas 55 returned to the inlet of the compressor V3 and a liquid which passes over the barrier P.
  • a portion 31 of the liquid is vaporized in the exchanger E2 and joins the inlet of the compressor V3.
  • the other part 53 serves to cool the head condenser C1 of the column K2, as before.
  • the bottom methane 39 of column K3 is reheated in exchanger E1 to exit the apparatus as a product.
  • Column K2 has a head condenser C1, consisting of a plate heat exchanger, and a bottom reboiler R2 heated by the ring nitrogen.
  • the overhead gas 27 of the column K2 partially condenses in the condenser C1, the formed liquid L, 29 being returned to the top of the column K2 and in part and the remaining gas V, enriched in nitrogen, being heated in the exchangers E2, E1 as a gas 31.
  • a liquid 53 from the top condenser C2 of the column K3 vaporizes by heat exchange with the gas 27 in the condenser C1 forming the gas 55 sent to the inlet of the compressor V3.
  • the tank liquor 21 enriched in carbon monoxide and depleted of nitrogen is expanded.
  • This liquid at 6.5 bar is sent to a phase separator whose liquid is used in part to cool the condenser C1.
  • the condenser of the column head CO / N 2 K2 column is cooled by vaporization of at least a portion of the tank liquid 33 of the column CO / N 2 K2 after expansion and vaporization of the liquid nitrogen 53 average pressure.
  • Spraying the tank liquid 33 after expansion makes it possible to considerably reduce the nitrogen cycle flow rate to be vaporized in condenser Ci, which reduces the nitrogen cycle flow rate and therefore the power of the nitrogen cycle compressor V1, V2, V3
  • Gas 31 is a carbon monoxide rich product of the process.
  • the operating pressure of the denitrogenation column K2 is at least 7 bar abs, or even 8 bar abs; the operating pressure of the separation column of carbon monoxide and methane K3 is at least 5 bar abs, or even 6 bar abs.
  • the hydrogen-depleted fluid is sent to a denitrogenation column (K2) having a top condenser (C1) and a bottom reboiler (R2) to produce a column-enriched nitrogen enriched gas and a nitrogen-depleted liquid in column vats,
  • the condenser of the denitrogenation column is cooled by means of a nitrogen cycle using a nitrogen compressor (V1, V2, V3) to at least a first stage and a second stage, the inlet pressure of the first floor being lower than that of the second floor,
  • Expansion tank liquid (21) from the denitrogenation column is sent to the top condenser of the denitrogenation column to vaporize at least partially by heat exchange in a heat exchanger of the condenser with the gas enriched in nitrogen which is condensed,
  • the bottom liquid (33) of the denitrogenization column (K2) is sent to a carbon monoxide and methane separation column (K3) comprising a top condenser (C2) which is a bath vaporizer placed in a a bath of liquid or
  • step ii) comprises a distillation step in a column (K3) for separating carbon monoxide and methane to separate a methane-depleted flowrate from a methane-enriched flow and at least a part of the depleted flow rate of methane (41) is the depleted fluid

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Abstract

A method for separating a gas mixture comprising carbon monoxide, nitrogen and hydrogen involves sending a hydrogen-depleted fluid to a denitrification column (K2) having a top condenser (C1) and a bottom reboiler (R2) in order to produce a nitrogen-enriched gas at the top of the column and a nitrogen-depleted liquid at the bottom of the column, cooling the condenser of the denitrification column by means of a nitrogen cycle using a nitrogen compressor (V1,V2,V3), vaporising, in the heat exchanger of the condenser, the liquid nitrogen (53) from the nitrogen cycle, and returning the nitrogen (55) vaporised in the heat exchanger to the nitrogen compressor.

Description

PROCEDE ET APPAREIL DE SEPARATION CRYOGENIQUE D’UN GAZ DE SYNTHESE CONTENANT UNE ETAPE DE SEPARATION DE L’AZOTE  METHOD AND APPARATUS FOR CRYOGENIC SEPARATION OF A SYNTHESIS GAS CONTAINING A NITROGEN SEPARATION STEP
La présente invention est relative à un procédé et à un appareil de séparation cryogénique d’un gaz de synthèse contenant de l’azote. Habituellement ce gaz contient du monoxyde de carbone, de l’hydrogène, du méthane et de l’azote. Il contient de préférence moins que 50% mol de méthane. Il contient de préférence plus que 10% mol de monoxyde de carbone. The present invention relates to a method and an apparatus for cryogenic separation of a synthesis gas containing nitrogen. Usually this gas contains carbon monoxide, hydrogen, methane and nitrogen. It preferably contains less than 50 mol% of methane. It preferably contains more than 10 mol% of carbon monoxide.
Les unités de production de monoxyde de carbone et d’hydrogène peuvent être séparées en deux parties :  The production units for carbon monoxide and hydrogen can be separated into two parts:
• génération du gaz de synthèse (mélange contenant H2, CO, CH4, CO2, Ar et N2 essentiellement). Parmi les diverses voies industrielles de production de gaz de synthèse, celle à base de gazéification de charbon semble se développer de plus en plus notamment dans les pays riches en dépôts de charbon comme la Chine. Le procédé d’oxydation partielle du gaz naturel peut s’avérer également intéressant pour la production de CO seul ou avec des rapports de production H2/CO faibles. Une autre voie est le reformage à la vapeur. • generation of the synthesis gas (mixture containing H2, CO, CH 4 , CO2, Ar and N2 essentially). Among the various synthetic gas production industries, the one based on coal gasification seems to develop more and more particularly in countries rich in coal deposits such as China. The partial oxidation process of natural gas can also be interesting for the production of CO alone or with low H2 / CO production ratios. Another way is steam reforming.
• purification du gaz de synthèse. On retrouve :  • purification of synthesis gas. We find :
une unité de lavage avec un solvant liquide pour éliminer la plus grande partie des gaz acides contenus dans le gaz de synthèse  a washing unit with a liquid solvent to remove most of the acid gases contained in the synthesis gas
une unité d’épuration sur lit d’adsorbants. an adsorbent bed purification unit.
S une unité de séparation par voie cryogénique dite boite froide pour la production de CO.  S cryogenic separation unit called cold box for the production of CO.
Dans le cas où le gaz de synthèse est produit à partir d’une gazéification de charbon à lit entraîné ou lit fluidisé, le procédé de la boite froide est la condensation partielle. Dans le cas où le gaz de synthèse est contaminé avec du méthane, par exemple pour les applications MEG, TDI/MDI ou PC, il est nécessaire d’inclure une colonne de séparation du CH4 dans la boite froide. Dans le cas où le gaz de synthèse est contaminé avec de l’azote, par exemple si de l’azote est utilisé pour transporter le charbon, il est nécessaire d’inclure une colonne de séparation de l’azote dans la boite froide. Dans DE19541339, une colonne CO/N2 est positionnée en amont d’une colonne CO/CH4. Le rebouillage de la colonne CO/CH4 est assuré par condensation de l’azote de cycle. La condensation en la tête de colonne CO/N2 est assurée par vaporisation de liquide N2 du cycle à basse pression. In the case where the synthesis gas is produced from entrained bed or fluidized bed coal gasification, the cold box process is partial condensation. In the case where the synthesis gas is contaminated with methane, for example for the MEG, TDI / MDI or PC applications, it is necessary to include a CH 4 separation column in the cold box. In the case where the synthesis gas is contaminated with nitrogen, for example if nitrogen is used to transport the coal, it is necessary to include a nitrogen separation column in the cold box. In DE19541339, a CO / N2 column is positioned upstream of a CO / CH 4 column. The reboiling of the CO / CH 4 column is ensured by condensation of the ring nitrogen. Condensation at the top of column CO / N 2 is provided by vaporization of liquid N2 of the low pressure cycle.
L'azote vaporisé dans les condenseurs des colonnes CO/N2 et CO/CH4 retourne à l'aspiration du compresseur du cycle d’azote. The vaporized nitrogen in the condensers of the CO / N 2 and CO / CH 4 columns returns to the compressor suction of the nitrogen cycle.
La colonne CO/N2 opère à une pression relativement basse (2,6 bar). The CO / N column 2 operates at a relatively low pressure (2.6 bar).
La pression de la colonne CO/CH4 est relativement basse. The pressure of the CO / CH 4 column is relatively low.
La condensation de tête de la colonne CO/N2 est assurée par vaporisation de la cuve de la colonne CO/CH4 et en complément par réchauffement de la fraction riche en hydrogène du pot de condensation partielle du gaz de synthèse The condensation of the top of the CO / N2 column is ensured by vaporization of the tank of the CO / CH 4 column and in addition by heating the hydrogen-rich fraction of the partial condensing pot of the synthesis gas.
Le produit CO à la sortie de la colonne CO/N2 revient à l’aspiration du compresseur CO pour être comprimé jusqu’à la pression requise.  The product CO at the outlet of the column CO / N2 returns to the suction of the compressor CO to be compressed to the required pressure.
Le condenseur de tête de la colonne CO/N2 a un volume important car le complément est apporté par réchauffement de l’hydrogène, donc un débit gazeux important : comme cet échangeur doit être positionné en hauteur par rapport à la tête de la colonne CO/N2, son volume important rendrait difficile le transport du paquet contenant la colonne CO/N2.  The top condenser of the CO / N2 column has a large volume because the complement is provided by heating the hydrogen, so a large gas flow: as this exchanger must be positioned in height relative to the head of the column CO / N2, its large volume would make it difficult to transport the package containing the column CO / N2.
La configuration conduit à une consommation d’énergie au niveau du compresseur de cycle CO importante car le CO produit doit être comprimé  The configuration leads to a significant energy consumption at the CO cycle compressor because the product CO has to be compressed
Ceci nécessite l’investissement d’un compresseur CO plus coûteux qu’un compresseur N2.  This requires the investment of a more expensive CO compressor than a N2 compressor.
Le couplement condenseur CO/N2 et rebouilleur CO/CH4 rend difficile le fonctionnement de l’unité lorsque les teneurs en CH4 et N2 dans le gaz de synthèse entrant varient. The CO / N2 condenser coupling and CO / CH 4 reboiler makes the operation of the unit difficult when the CH 4 and N 2 contents in the incoming synthesis gas vary.
DE2814600 décrit un procédé de séparation utilisant une colonne d’élimination de méthane, suivie d’une double colonne dont la tête de la colonne de séparation CO/argon chauffe la cuve de la colonne de déazotation.  DE2814600 describes a separation process using a methane removal column, followed by a double column whose head of the CO / argon separation column heats the tank of the denitrogenation column.
Le condenseur de tête de déazotation vaporise le liquide de la cuve de la colonne de déazotation après détente et vaporisation d’un liquide de cycle azote. Par contre le cycle d’azote ne sert pas comme fluide réfrigérant pour condenser la tête de séparation d’une colonne de séparation CH4 ni dans la colonne de 28 ni dans la colonne 13. La tête de colonne de séparation de CH4 13 est refroidi par de l'hydrogène. Ceci conduit à un échangeur en tête de colonne 13 plus gros qui prend plus de place dans le paquet de la boite froide et donc est plus difficile à transporter. De plus l’apport de froid n'est pas suffisant et il reste du CH4 dans le fluide envoyé à la deuxième colonne alors que selon l'invention, une seule colonne enlève tout le CH4. The denitrogen head condenser vaporizes the liquid from the tank of the denitrogenation column after expansion and vaporization of a nitrogen cycle liquid. On the other hand, the nitrogen cycle is not used as a cooling fluid to condense the separation head of a separation column CH4, or in the column of 28 nor in the column 13. The CH4 13 separation column head is cooled by hydrogen. This leads to a larger exchanger 13 at the top of the column which takes up more space in the package of the cold box and is therefore more difficult to transport. In addition, the cold supply is not sufficient and CH4 remains in the fluid sent to the second column whereas according to the invention, a single column removes all the CH4.
DE2814860 a un circuit N2 vers le rebouiileur de la cuve de la colonne argon/CO qui est aussi à une pression supérieure à celle de la présente invention où le rebouillage de la colonne CO/CH4 est effectué par le gaz de synthèse.  DE2814860 has a N2 circuit to the argon / CO column vessel scrubber which is also at a higher pressure than that of the present invention where the CO / CH4 column is reboiled by the synthesis gas.
Selon cet art antérieur, le rebouillage de la séparation CO/N2 est apporté par le cycle N2 via le rebouiileur de cuve de la colonne argon/CO, ce qui requiert une pression plus haute que celle selon l’invention, où on a besoin d’azote de rebouillage uniquement à la pression de la colonne CO/N2.  According to this prior art, the reboiling of the CO / N2 separation is provided by the N2 cycle via the tank refluxer of the argon / CO column, which requires a higher pressure than that according to the invention, where it is necessary to nitrogen reboiling only at the pressure of the column CO / N2.
Selon un objet de l’invention, il est prévu un procédé de séparation d’un mélange gazeux comprenant du monoxyde de carbone, de l’azote, de l’hydrogène et éventuellement du méthane dans lequel : According to one object of the invention, there is provided a method for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and optionally methane in which:
i) On refroidit le mélange dans un échangeur de chaleur,  i) the mixture is cooled in a heat exchanger,
ii) On sépare le mélange refroidi dans l’échangeur de chaleur par au moins une étape de condensation partielle et/ou de distillation et/ou de lavage afin de former un fluide appauvri en hydrogène contenant du monoxyde de carbone et de l’azote,  ii) separating the cooled mixture in the heat exchanger by at least one partial condensation and / or distillation and / or washing step to form a hydrogen-depleted fluid containing carbon monoxide and nitrogen,
iii) On envoie le fluide appauvri en hydrogène vers une colonne de déazotation ayant un condenseur de tête et un rebouilleur de cuve pour produire un gaz enrichi en azote en tête de colonne et un liquide appauvri en azote en cuve de colonne, iv) On refroidit le condenseur de la colonne de déazotation au moyen d’un cycle d’azote utilisant un compresseur d’azote à au moins un premier étage et une deuxième étage, la pression d’entrée de la première étage étant plus basse que celle du deuxième étage,  iii) The hydrogen-depleted fluid is sent to a denitrogenation column having a head condenser and a bottom reboiler to produce a nitrogen-enriched gas at the top of the column and a column-depleted nitrogen-depleted liquid. iv) Cooling the condenser of the denitrogenation column by means of a nitrogen cycle using a nitrogen compressor with at least a first stage and a second stage, the inlet pressure of the first stage being lower than that of the second stage ,
v) On détend du liquide de cuve de la colonne de déazotation, on l’envoie vers le condenseur de tête de la colonne de déazotation pour se vaporiser au moins partiellement par échange de chaleur dans un échangeur de chaleur du condenseur avec le gaz enrichi en azote qui s’en trouve condensé, et  v) The reactor liquid is expanded from the denitrogenation column and sent to the head condenser of the denitrogenation column to vaporize at least partially by heat exchange in a condenser heat exchanger with the enriched gas. nitrogen which is condensed, and
vi) On vaporise également dans l’échangeur de chaleur du condenseur de l’azote liquide provenant du cycle d’azote et on renvoie l’azote vaporisé dans l’échangeur de chaleur à l’entrée du deuxième étage du compresseur d’azote et vi) The condenser is also vaporized in the liquid nitrogen condenser from the nitrogen cycle and vaporized nitrogen is returned in the heat exchanger at the inlet of the second stage of the nitrogen compressor and
a) on envoie du liquide de cuve de la colonne de déazotation vers une colonne de séparation de monoxyde de carbone et de méthane comprenant un condenseur de tête qui est un vaporiseur à bain placé dans un bain de liquide ou  a) the bottom liquid of the denitrogenation column is sent to a carbon monoxide and methane separation column comprising a head condenser which is a bath vaporizer placed in a liquid bath or
b) la séparation de l’étape ii) comprend une étape de distillation dans une colonne de séparation de monoxyde de carbone et de méthane pour séparer un débit appauvri en méthane d’un débit enrichi en méthane et au moins une partie du débit appauvri en méthane constitue le fluide appauvri en hydrogène alimentant la colonne de déazotation, la colonne de séparation de monoxyde de carbone et de méthane comprenant un condenseur de tête qui est un vaporiseur à bain placé dans un bain de liquide le bain de liquide de a) ou b) étant alimenté par de l’azote liquide provenant du cycle d’azote.  b) the separation of step ii) comprises a distillation step in a carbon monoxide and methane separation column for separating a methane-depleted flow rate from a methane-enriched flow rate and at least a part of the depleted flow rate; methane is the hydrogen-depleted fluid feeding the denitrogenation column, the carbon monoxide and methane separation column comprising a head condenser which is a bath vaporizer placed in a liquid bath the liquid bath of a) or b ) being fed with liquid nitrogen from the nitrogen cycle.
Selon d’autres aspects facultatifs de l’invention : According to other optional aspects of the invention:
le mélange contient du méthane.  the mixture contains methane.
la séparation de l’étape ii) comprend une étape de distillation dans une colonne de séparation de monoxyde de carbone et de méthane pour séparer un débit appauvri en méthane d’un débit enrichi en méthane et au moins une partie du débit appauvri en méthane constitue le fluide appauvri en hydrogène alimentant la colonne de déazotation.  the separation of step ii) comprises a distillation step in a carbon monoxide and methane separation column for separating a methane depleted flow from a methane enriched flow and at least a portion of the methane depleted flow is the fluid depleted of hydrogen supplying the denitrogenation column.
on envoie du liquide de cuve de la colonne de déazotation vers une colonne de séparation de monoxyde de carbone et de méthane.  the reactor liquid is sent from the denitrogenation column to a separation column of carbon monoxide and methane.
la colonne de séparation de monoxyde de carbone et de méthane comprend un condenseur de tête qui est un vaporiseur à bain placé dans un bain de liquide.  the carbon monoxide and methane separation column comprises a head condenser which is a bath vaporizer placed in a liquid bath.
le condenseur de tête de la colonne de séparation de monoxyde de carbone et de méthane est alimenté par de l’azote liquide provenant du cycle d’azote. on envoie de l’azote liquide du condenseur de tête de la colonne de séparation de monoxyde de carbone et de méthane se vaporiser dans le condenseur de tête de la colonne de déazotation. the top condenser of the carbon monoxide and methane separation column is fed with liquid nitrogen from the nitrogen cycle. liquid nitrogen from the top condenser of the carbon monoxide and methane separation column is vaporized in the overhead condenser of the denitrogenation column.
on sépare le mélange refroidi dans l’échangeur de chaleur par au moins une étape de condensation partielle afin de former un gaz appauvri en hydrogène, on envoie le gaz appauvri en hydrogène à un niveau intermédiaire d’une colonne d’épuisement ayant un rebouilleur de cuve et on envoie du liquide de cuve de la colonne d’épuisement vers une colonne de déazotation selon le cas a) ou vers la colonne de séparation de monoxyde de carbone et de méthane selon le cas b).  the cooled mixture is separated in the heat exchanger by at least one partial condensation step in order to form a hydrogen-depleted gas, the hydrogen-depleted gas is sent to an intermediate level of a depletion column having a reboiler. tank and is sent from the bottom liquid of the depletion column to a denitrogenation column according to the case a) or to the separation column of carbon monoxide and methane as the case b).
on réchauffe le rebouilleur de la colonne d’épuisement et/ou le rebouilleur de la colonne de séparation de monoxyde de carbone et de méthane avec au moins d’une partie du mélange gazeux.  the reboiler of the exhaustion column and / or the reboiler of the carbon monoxide and methane separation column are heated with at least part of the gaseous mixture.
la pression d’opération de la colonne de déazotation est d’au moins 7 bars abs, voire 8 bars abs  the operating pressure of the denitrogenation column is at least 7 bar abs, or even 8 bar abs
la pression d’opération de la colonne de séparation de monoxyde de carbone et de méthane est d’au moins 5 bars abs, voire 6 bars abs.  the operating pressure of the separation column of carbon monoxide and methane is at least 5 bar abs, or even 6 bar abs.
le condenseur de tête de la colonne CO/CH4 est refroidi uniquement par de l’azote de cycle.  the top condenser of the CO / CH4 column is cooled only with cycle nitrogen.
on réchauffe le rebouilleur de la colonne de déazotation au moyen de l’azote de cycle.  the reboiler of the denitrogenation column is heated by means of the cycle nitrogen.
l’azote utilisé pour réchauffer le rebouilleur de la colonne de déazotation est à la pression maximale du cycle azote .  the nitrogen used to heat the reboiler of the denitrogenation column is at the maximum pressure of the nitrogen cycle.
l’azote envoyé au bain du condenseur de la colonne CO/CH4 est condensé à la pression maximale du cycle azote.  the nitrogen sent to the condenser bath of the CO / CH4 column is condensed at the maximum pressure of the nitrogen cycle.
Selon un autre objet de l’invention, il est prévu un appareil de séparation d’un mélange gazeux comprenant du monoxyde de carbone, de l’azote, de l’hydrogène et éventuellement du méthane comprenant un échangeur de chaleur pour refroidir le mélange, des moyens de séparation du mélange refroidi dans l’échangeur de chaleur par au moins une étape de condensation partielle et/ou de distillation et/ou de lavage afin de former un fluide appauvri en hydrogène contenant du monoxyde de carbone et de l’azote, une colonne de déazotation ayant un condenseur de tête et éventuellement un rebouilleur de cuve, une conduite pour envoyer le fluide appauvri en hydrogène vers la colonne de déazotation pour produire un gaz enrichi en azote en tête de colonne et un liquide appauvri en azote en cuve de colonne, un cycle d’azote utilisant un compresseur d’azote à au moins un premier étage et une deuxième étage, la pression d’entrée de la première étage étant plus basse que celle du deuxième étage, des moyens pour envoyer du liquide du cycle d’azote vers le condenseur de la colonne de déazotation, des moyens pour détendre du liquide de cuve de la colonne de déazotation, des moyens pour envoyer le liquide détendu vers le condenseur de tête de la colonne de déazotation pour se vaporiser au moins partiellement par échange de chaleur dans un échangeur de chaleur du condenseur avec le gaz enrichi en azote qui s’en trouve condensé et des moyens pour envoyer de l’azote vaporisé dans l’échangeur de chaleur à l’entrée du deuxième étage du compresseur d’azote, une colonne de séparation de monoxyde de carbone et de méthane comprenant un condenseur de tête qui est un vaporiseur à bain placé dans un bain de liquide, According to another object of the invention, there is provided an apparatus for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and optionally methane comprising a heat exchanger for cooling the mixture, means for separating the cooled mixture in the heat exchanger by at least one partial condensation and / or distillation and / or washing step in order to form a hydrogen-depleted fluid containing carbon monoxide and nitrogen, a denitrogenation column having a head condenser and optionally a bottom reboiler, a conduit for delivering the depleted fluid to hydrogen to the denitrogenation column to produce a nitrogen enriched gas at the column head and a column depleted nitrogen liquid, a nitrogen cycle using a nitrogen compressor to at least a first stage and a second stage , the inlet pressure of the first stage being lower than that of the second stage, means for sending liquid from the nitrogen cycle to the condenser of the denitrogenation column, means for expanding the bottom liquid of the column denitrogenation means for sending the expanded liquid to the top condenser of the denitrogenation column to vaporize at least partially by heat exchange in a heat exchanger of the condenser with the nitrogen-enriched gas which is condensed therein and means for sending vaporized nitrogen into the heat exchanger at the inlet of the second stage of the nitrogen compressor, a carbon monoxide and methane separation column incorporating a head condenser which is a bath vaporizer placed in a liquid bath,
a) des moyens pour envoyer le liquide de cuve de la colonne de déazotation à la colonne de séparation de monoxyde de carbone et de méthane ou b) la colonne de séparation de monoxyde de carbone et de méthane des moyens faisant partie des moyens de séparation du mélange refroidi dans l’échangeur de chaleur par au moins une étape de distillation  a) means for sending the vessel liquid from the denitrogenation column to the carbon monoxide and methane separation column; or b) the carbon monoxide and methane separation column of the means forming part of the separation means of the carbon monoxide and methane separation column. cooled mixture in the heat exchanger by at least one distillation step
l’appareil comprenant également des moyens pour envoyer de l’azote liquide provenant du cycle d’azote vers le condenseur de tête de la colonne de séparation de monoxyde de carbone et de méthane. the apparatus also comprising means for supplying liquid nitrogen from the nitrogen cycle to the overhead condenser of the carbon monoxide and methane separation column.
L’appareil peut comprendre des moyens pour envoyer de l’azote liquide du condenseur de tête de la colonne de séparation de monoxyde de carbone et de méthane vers le condenseur de tête de la colonne de déazotation. The apparatus may include means for supplying liquid nitrogen from the overhead condenser of the carbon monoxide and methane separation column to the overhead condenser of the denitrogenation column.
L’appareil peut comprendre au moins un séparateur de phase pour séparer le mélange refroidi dans l’échangeur de chaleur par une étape de condensation partielle afin de former un gaz appauvri en hydrogène, une colonne d’épuisement et des moyens pour envoyer le gaz appauvri en hydrogène à un niveau intermédiaire de la colonne d’épuisement. Selon l’invention le rebouillage de la colonne CO/CHU est par refroidissement du gaz de synthèse alors qu'il est par condensation du cycle dans le DEXX : dans notre schéma cela a pour avantage de pouvoir augmenter la pression de la colonne CO/CH4 sans augmenter la pression sortie du compresseur N2. The apparatus may comprise at least one phase separator for separating the cooled mixture into the heat exchanger by a partial condensation step to form a hydrogen-depleted gas, a depletion column and means for delivering the depleted gas. in hydrogen at an intermediate level of the exhaustion column. According to the invention the reboiling of the CO / CHU column is by cooling the synthesis gas while it is by condensation of the cycle in the DEXX: in our scheme this has the advantage of being able to increase the pressure of the CO / CH column. 4 without increasing the output pressure of compressor N2.
Le condenseur de la tête de colonne CO/N2 est refroidi par vaporisation d'au moins une partie du liquide de cuve de la colonne CO/N2 après détente ainsi que par vaporisation de liquide IM2 à moyenne pression. Dans l’art antérieur, le refroidissement s’effectue par vaporisation de liquide N2 du cycle à basse pression. Le fait de vaporiser le liquide de cuve après détente permet de réduire considérablement le débit de cycle N2 à vaporiser dans le condenseur, ce qui réduit le débit de cycle N2 et donc la puissance du compresseur de cycle N2. Dans l’art antérieur le débit d’azote est relativement important par rapport au débit de CO produit. The condenser of the column head CO / N 2 is cooled by vaporization of at least a portion of the bottom liquid of the column CO / N2 after expansion and by vaporization of liquid IM2 at medium pressure. In the prior art, the cooling is carried out by vaporization of liquid N2 of the low-pressure cycle. Spraying the vessel liquid after expansion makes it possible to considerably reduce the N 2 cycle flow rate to be vaporized in the condenser, which reduces the N 2 cycle flow rate and therefore the power of the N 2 cycle compressor. In the prior art the nitrogen flow rate is relatively large compared to the rate of CO produced.
Selon l’invention, l'azote vaporisé dans les condenseurs des colonnes CG/IM2 et CO/CH4 retourne à un inter-étage du compresseur de N2 alors que dans l’art antérieur il retourne à l'aspiration du compresseur. L'art antérieur conduit donc à augmenter l'énergie de compression du cycle. Dans l’art antérieur ; le débit 54 retourne à la même pression (2,4 bar) que le débit 2 nécessaire au refroidissement du gaz de synthèse dans le E2 alors que dans notre schéma le débit de N2 vaporisé dans les condenseurs retourne au compresseur 2 à une pression plus haute que le débit de N2 nécessaire au refroidissement du gaz de synthèse. Dans notre cas cela est rendu possible car on opère la colonne CO/N2 à une pression plus élevée (au moins 7 bars, par exemple à 8,5 bar) par rapport à l’art antérieur (2,6 bar). According to the invention, the vaporized nitrogen in the condensers of the columns CG / IM2 and CO / CH 4 returns to an inter-stage compressor N 2 while in the prior art it returns to the suction of the compressor. The prior art therefore leads to increase the compression energy of the cycle. In the prior art; the flow 54 returns to the same pressure (2.4 bar) as the flow rate 2 necessary for the cooling of the synthesis gas in the E2 whereas in our diagram the flow rate of N2 vaporized in the condensers returns to the compressor 2 at a higher pressure than the flow rate of N2 necessary for cooling the synthesis gas. In our case this is made possible because the CO / N2 column is operated at a higher pressure (at least 7 bar, for example at 8.5 bar) compared to the prior art (2.6 bar).
- La figure 3 du DE102012020469 inclut une pompe pour augmenter la pression de la colonne CO/CH4, mais celle-ci reste faible (3.8 bar) par rapport aux schémas selon i’invention (au moins 5 bars, voire au moins 6 bars) et y compris dans la figure 3, le liquide N2 du condenseur de la colonne CO/CH4 est à basse pression et retourne à l'aspiration du compresseur alors que dans notre schéma l'azote du condenseur de tête de colonne CO/CH4 retourne à un inter-étage du compresseur N2 (à une pression pius élevée que l’azote qui sert à refroidir le gaz de synthèse dans l'échangeur principal).  - Figure 3 of DE102012020469 includes a pump to increase the pressure of the CO / CH4 column, but it remains low (3.8 bar) compared to the schemes according to the invention (at least 5 bar, or even at least 6 bar) and including in figure 3, the liquid N2 of the condenser of the column CO / CH4 is at low pressure and returns to the suction of the compressor whereas in our diagram the nitrogen of the condenser of head of column CO / CH4 returns to an inter-stage compressor N2 (at a higher pressure than the nitrogen that serves to cool the synthesis gas in the main exchanger).
Corne selon l’invention la colonne CO/N2 est à plus haute pression, ceci permet de produire le CO directement sans recompression. L’énergie de condensation de la tête de la colonne CO/N2 est apportée par vaporisation du liquide de cuve après détente et complément par vaporisation d’azote basse pression du cycle N2. Ceci réduit la taille du condenseur de tête et rend transportable le paquet contenant la colonne CO/N2 et son condenseur de tête. Horn according to the invention the column CO / N 2 is at higher pressure, this allows to produce CO directly without recompression. The condensation energy of the head of the CO / N2 column is provided by vaporization of the bottom liquid after expansion and addition by vaporization of low-pressure nitrogen of the N 2 ring. This reduces the size of the overhead condenser and makes the package containing the CO / N2 column and its overhead condenser transportable.
L’invention sera décrite de manière plus détaillée en se référant aux deux figures qui représentent chacune un procédé de séparation selon l’invention.  The invention will be described in more detail with reference to the two figures which each represent a separation method according to the invention.
Dans la Figure 1 , un mélange gazeux 1 , issu par exemple d’une gazéification de charbon, contient du monoxyde de carbone, de l’hydrogène, du méthane, de l’eau et de l’azote. Le gaz 1 est épuré dans des lits d’adsorbants 3A, 3B et refroidi dans un refroidisseur 4. Ensuite il est envoyé à un premier échangeur de chaleur E1 pour être refroidi. Des débits partiels du gaz de synthèse sont utilisés pour réchauffer les réchauffeurs R1 ,R2 dessinés deux fois à des endroits différents du dessin pour des raisons de clarté. Après détente dans une vanne, il est séparé dans un séparateur de phases S1 formant un gaz 5 et un liquide 7. Le gaz 5 est refroidi dans un échangeur de chaleur E2, détendu, envoyé à un séparateur de phases S4. Le gaz 9 de ce séparateur de phases S4, riche en hydrogène, se réchauffe dans les échangeurs de chaleur E2, E1 et une partie du gaz sert à régénérer les lits d’adsorbants 3A,3B. Une partie 1 1 du liquide du séparateur de phases S4 est détendue et envoyée en tête d’une colonne d’épuisement K1 opérant à 17,6 bar. La colonne K1 n’a pas de condenseur de tête mais a un rebouilleur de cuve R1 . Le reste 13 du liquide du séparateur de phases S4 est détendu et envoyé à un séparateur de phases S3. Le gaz de tête 17 de la colonne K1 se réchauffe dans les échangeurs E1 , E2.  In Figure 1, a gaseous mixture 1, for example from a gasification of coal, contains carbon monoxide, hydrogen, methane, water and nitrogen. The gas 1 is purified in adsorbent beds 3A, 3B and cooled in a cooler 4. Then it is sent to a first heat exchanger E1 to be cooled. Partial flow rates of the synthesis gas are used to heat the R1, R2 heaters drawn twice at different locations of the drawing for reasons of clarity. After expansion in a valve, it is separated in a phase separator S1 forming a gas 5 and a liquid 7. The gas 5 is cooled in a heat exchanger E2, expanded, sent to a phase separator S4. The gas 9 of this phase separator S4, rich in hydrogen, is heated in the heat exchangers E2, E1 and part of the gas serves to regenerate the adsorbent beds 3A, 3B. Part 1 1 of the liquid of the phase separator S4 is expanded and sent to the top of a depletion column K1 operating at 17.6 bar. Column K1 has no overhead condenser but has a reboiler R1. The remainder 13 of the liquid of the phase separator S4 is expanded and sent to a phase separator S3. The overhead gas 17 of the column K1 is heated in the exchangers E1, E2.
Le liquide 7 du séparateur de phases S1 se mélange avec d’autres fluides (gaz de tête de séparateur S3, dérivé du liquide 13 provenant du séparateur S4) pour former le débit 8 qui est envoyé à un séparateur de phases S2 et ensuite à un niveau intermédiaire de la colonne d’épuisement K1 .  The liquid 7 of the phase separator S1 mixes with other fluids (separator head gas S3, derived from the liquid 13 from the separator S4) to form the flow 8 which is sent to a phase separator S2 and then to a intermediate level of the K1 exhaustion column.
Le gaz du séparateur de phases S3 et le liquide du séparateur de phases S3 après vaporisation dans l’échangeur E2 sont mélangés avec le fluide 7 pour alimenter la colonne K1 .  The gas of the phase separator S3 and the liquid of the phase separator S3 after vaporization in the exchanger E2 are mixed with the fluid 7 to feed the column K1.
Du liquide de cuve 19 de la colonne K1 est pris à -154°C, détendu à 8,3 bars, envoyé au séparateur de phases S5 et le gaz et le liquide du séparateur de phases sont envoyés un niveau intermédiaire de la colonne CO/N2 K2 opérant à 8,3 bars. La colonne K2 a un condenseur de tête C1 , constitué par un échangeur de chaleur à plaques, et un rebouilleur de cuve R2. Bottle liquid 19 from column K1 is taken at -154 ° C, slackened to 8.3 bar, sent to the S5 phase separator and the gas and liquid from the phase separator are sent to an intermediate level of the CO column. N2 K2 operating at 8.3 bars. The column K2 has a head condenser C1, consisting of a plate heat exchanger, and a reboiler R2.
Le gaz de tête 27 de la colonne K2 se condense partiellement dans le condenseur C1 , le liquide formé L, 29 étant renvoyé vers la tête de la colonne K2 et en partie et le gaz restant V, enrichi en azote, étant réchauffé dans les échangeurs E2, E1 en tant que gaz 31.  The overhead gas 27 of the column K2 partially condenses in the condenser C1, the formed liquid L, 29 being returned to the top of the column K2 and in part and the remaining gas V, enriched in nitrogen, being heated in the exchangers E2, E1 as a gas 31.
Un liquide 53 provenant du condenseur de tête C2 de la colonne K3 se vaporise par échange de chaleur avec le gaz 27 dans le condenseur C1 formant le gaz 55 envoyé à l’entrée du compresseur V3.  A liquid 53 from the top condenser C2 of the column K3 vaporizes by heat exchange with the gas 27 in the condenser C1 forming the gas 55 sent to the inlet of the compressor V3.
Le liquide de cuve 33 enrichi en monoxyde de carbone et appauvri en azote est divisé en deux 21 ,35 et détendu. Une partie détendue 21 à 6,5 bars est envoyée à un séparateur de phases dont le liquide sert en partie à refroidir le condenseur C1. Ainsi le condenseur de la tête C1 de colonne CO/N2 K2 est refroidi par vaporisation d'au moins une partie du liquide de cuve 33 de la colonne CO/N2 K2 après détente et vaporisation de l’azote liquide 53 à moyenne pression. Le fait de vaporiser le liquide de cuve 33 après détente permet de réduire considérablement le débit de cycle d’azote à vaporiser dans le condenseur C1 , ce qui réduit le débit de cycle d’azote et donc la puissance du compresseur de cycle d’azote V1 , V2, V3  The tank liquor 33 enriched in carbon monoxide and depleted of nitrogen is divided in two 21, 35 and expanded. A relaxed portion 21 to 6.5 bar is sent to a phase separator whose liquid is used in part to cool the condenser C1. Thus, the condenser of the column head CO / N2 K2 K2 is cooled by vaporization of at least a portion of the tank liquid 33 of the column CO / N2 K2 after expansion and vaporization of the liquid nitrogen 53 at medium pressure. Spraying the tank liquid 33 after expansion considerably reduces the nitrogen cycle flow rate to be vaporized in the condenser C1, which reduces the nitrogen cycle flow rate and therefore the power of the nitrogen cycle compressor. V1, V2, V3
Le reste du liquide provenant du séparateur S8 et la fraction 35 alimentent la colonne CO/CH4 K3 après passage dans un séparateur de phases S6, dont le gaz et le liquide sont envoyés à des niveaux différents intermédiaires de la colonne K3. The remainder of the liquid from the separator S8 and the fraction 35 feed the column CO / CH 4 K3 after passing through an S6 phase separator, the gas and the liquid of which are sent to different intermediate levels of the column K3.
La colonne K3 a un condenseur de tête C2, constitué par un échangeur de chaleur à plaques disposé dans un bain de liquide à vaporiser, et un rebouilleur de cuve R3. Le gaz de tète enrichi en monoxyde de carbone se condense dans le condenseur C2 et le liquide de cuve 39, riche en méthane, est détendu et réchauffé dans l’échangeur E1. La colonne K3 fonctionne à 6,6 bars.  Column K3 has a head condenser C2, consisting of a plate heat exchanger disposed in a bath of liquid to be vaporized, and a reboiler R3. The carbon monoxide enriched head gas condenses in the condenser C2 and the methane-rich bottom liquid 39 is expanded and heated in the E1 exchanger. Column K3 operates at 6.6 bars.
L’échangeur à plaques est entouré par une barrière annulaire formant une paroi de débordement P. Ainsi le liquide entourant l’échangeur peut passer par-dessus la barrière P pour être soutiré comme liquides 43, 53.  The plate heat exchanger is surrounded by an annular barrier forming an overflow wall P. Thus the liquid surrounding the heat exchanger can pass over the barrier P to be withdrawn as liquids 43, 53.
Le condenseur de tête C2 de la colonne K3 est refroidi par de l’azote comprimé et détendu 59 provenant du compresseur de cycle d’azote V1 , V2, V3 après refroidissement dans les échangeurs E1 , E2. L’azote vaporisé est renvoyé en amont du dernier étage V3 du compresseur de cycle d’azote. L’azote à la pression de sortie de l’étage V3 sert également à rebouillir le rebouilleur R2 de la colonne K2. The head condenser C2 of the column K3 is cooled by compressed and expanded nitrogen 59 from the nitrogen cycle compressor V1, V2, V3 after cooling in the exchangers E1, E2. The vaporized nitrogen is returned upstream of the last stage V3 of the nitrogen cycle compressor. Nitrogen at the outlet pressure of stage V3 also serves to reboil reboiler R2 of column K2.
Les rebouilleurs R1 et R3 des colonnes K1 et K3 sont réchauffés par des débits partiels de l’alimentation 1 en aval de l’échangeur E1 et en amont du séparateur de phases S1 . Ce rebouillage de la colonne CO/CH4 K3 est par refroidissement du gaz de synthèse a pour avantage de pouvoir augmenter la pression de la colonne CO/CH4 sans augmenter la pression de sortie du compresseur de cycle azote. Les débits partiels envoyés aux rebouilleurs R1 , R3 sont à la même température et la même pression. The reboilers R1 and R3 of the columns K1 and K3 are reheated by partial flow rates of the feed 1 downstream of the exchanger E1 and upstream of the phase separator S1. This reboiling of the CO / CH 4 K 3 column by cooling the synthesis gas has the advantage of being able to increase the pressure of the CO / CH 4 column without increasing the output pressure of the nitrogen cycle compressor. The partial flows sent to the reboiler R1, R3 are at the same temperature and the same pressure.
De l’azote liquide 53 de la cuve du condenseur C2 de la colonne K3 est envoyé se vaporiser dans le condenseur C1 de la colonne K3 et ensuite est renvoyé en aval de l’étage V2 et en amont de l’étage V3. Ainsi l’azote vaporisé dans les condenseurs Ci , C3 des colonnes CO/N2 K2 et CO/CH4 K3 retourne à un inter-étage du compresseur d’azote V1 , V2, Le débit de N2 57 vaporisé dans les condenseurs Ci , C2 retourne au compresseur N2 à une pression plus haute que le débit de N2 nécessaire au refroidissement du gaz de synthèse. Dans notre cas cela est rendu possible car on opère la colonne CO/N2 K2 à une pression plus élevée (8,5 bar) par rapport à l'art antérieur (2,6 bar).  Liquid nitrogen 53 from the tank of the condenser C2 of the column K3 is sent to vaporize in the condenser C1 of the column K3 and then is returned downstream of the stage V2 and upstream of the stage V3. Thus, the nitrogen vaporized in the condensers Ci, C3 of the columns CO / N2 K2 and CO / CH4 K3 returns to an interstage of the nitrogen compressor V1, V2. The flow rate of N2 57 vaporized in the condensers Ci, C2 returns compressor N2 at a higher pressure than the flow rate of N2 necessary for cooling the synthesis gas. In our case this is made possible because the column CO / N2 K2 is operated at a higher pressure (8.5 bar) compared to the prior art (2.6 bar).
Un gaz 41 riche en monoxyde de carbone sort de la colonne K3 à 6,6 bars à - 170,4°C et se réchauffe dans les échangeurs de chaleur E1 , E2. De préférence, aucun compresseur de monoxyde de carbone n’est utilisé. Il constitue un produit du procédé et n’a pas été comprimé.  A gas 41 rich in carbon monoxide leaves column K3 at 6.6 bars at -170.4 ° C and heats up in heat exchangers E1, E2. Preferably, no carbon monoxide compressor is used. It is a product of the process and has not been compressed.
Un apport d’azote liquide 69 permet de compenser les fuites du cycle d’azote. Envoyé à un séparateur de phase S7, le liquide formé se vaporise dans l’échangeur E2, se mélange avec le gaz du séparateur S7 et est envoyé à l’entrée du compresseur V1 .  A supply of liquid nitrogen 69 makes it possible to compensate for leaks in the nitrogen cycle. When sent to a phase separator S7, the liquid formed vaporizes in the exchanger E2, mixes with the gas of the separator S7 and is sent to the inlet of the compressor V1.
Une partie 47 de l'azote liquide du condenseur C2 est détendue, envoyée au séparateur S7 et le gaz formé 49 rentre à l’entrée du compresseur V1 .  A portion 47 of the liquid nitrogen of the condenser C2 is expanded, sent to the separator S7 and the formed gas 49 enters the inlet of the compressor V1.
Une autre partie 45 du même liquide est détendue à une pression plus basse et envoyée à la sortie du compresser V1 et l’entrée du compresseur V2.  Another part 45 of the same liquid is expanded to a lower pressure and sent to the output of the compressor V1 and the input of the compressor V2.
La pression d’opération de la colonne de déazotation K2 est d’au moins 7 bars abs, voire 8 bars abs ; la pression d’opération de la colonne de séparation de monoxyde de carbone et de méthane K3 est d’au moins 5 bars abs, voire 6 bars abs. Dans la Figure 2, l’ordre des colonnes de séparation de méthane et de monoxyde de carbone et de déazotation est inversé. The operating pressure of the denitrogenation column K2 is at least 7 bar abs, or even 8 bar abs; the operating pressure of the separation column of carbon monoxide and methane K3 is at least 5 bar abs, or even 6 bar abs. In Figure 2, the order of the separation columns of methane and carbon monoxide and denitrogenation is reversed.
Ainsi ie liquide 19 de la cuve de la colonne d’épuisement est envoyé, non pas à la colonne de déazotaîion, mais à un point intermédiaire de la colonne de séparation CO/CH4 K3 après séparation d’un séparateur de phases SS. Thus the liquid 19 of the tank of the exhaust column is sent, not to the deaerator column, but to an intermediate point of the CO / CH 4 K 3 separation column after separation of a SS phase separator.
La colonne CO/CH4 K3 a un rebouiiieur de cuve R3 chauffé par l’alimentation et un condenseur de tête C2 qui sert à condenser le gaz de tête 51 qui est renvoyé à la colonne K3 sous forme condensé. Le condenseur est refroidi avec de l’azote condensé 61 ,63 produit en condensant l’azote de cycle 59 provenant du compresseur V3 dans les échangeurs E1 , E2 et dans le rebouiiieur R2. Le liquide est partiellement vaporisé produisant un gaz 55 renvoyé à l’entrée du compresseur V3 et un liquide qui passe par-dessus la barrière P. Une partie 31 du liquide est vaporisée dans l’échangeur E2 et rejoint l’entrée du compresseur V3. L’autre partie 53 sert à refroidir ie condenseur de tête C1 de la colonne K2, comme précédemment. The column CO / CH 4 K3 has a feed-heated reactor vessel R3 and a head condenser C2 which serves to condense the overhead gas 51 which is returned to column K3 in condensed form. The condenser is cooled with condensed nitrogen 61, 63 produced by condensing the ring nitrogen 59 from the compressor V3 into the exchangers E1, E2 and the reboiler R2. The liquid is partially vaporized producing a gas 55 returned to the inlet of the compressor V3 and a liquid which passes over the barrier P. A portion 31 of the liquid is vaporized in the exchanger E2 and joins the inlet of the compressor V3. The other part 53 serves to cool the head condenser C1 of the column K2, as before.
Le méthane de cuve 39 de la colonne K3 est réchauffé dans l’échangeur E1 pour sortir de l'appareil comme produit. Le gaz de tête 26, enrichi en monoxyde de carbone et contenant de l’azote part vers ie milieu de la colonne de déazotation K2.  The bottom methane 39 of column K3 is reheated in exchanger E1 to exit the apparatus as a product. The overhead gas 26, enriched in carbon monoxide and containing nitrogen, leaves towards the middle of the denitrogenation column K 2.
La colonne K2 a un condenseur de tête C1 , constitué par un échangeur de chaleur à plaques, et un rebouilleur de cuve R2 chauffé par l’azote de cycle. Le gaz de tête 27 de la colonne K2 se condense partiellement dans le condenseur C1 , le liquide formé L, 29 étant renvoyé vers la tête de la colonne K2 et en partie et le gaz restant V, enrichi en azote, étant réchauffé dans les échangeurs E2, E1 en tant que gaz 31 .  Column K2 has a head condenser C1, consisting of a plate heat exchanger, and a bottom reboiler R2 heated by the ring nitrogen. The overhead gas 27 of the column K2 partially condenses in the condenser C1, the formed liquid L, 29 being returned to the top of the column K2 and in part and the remaining gas V, enriched in nitrogen, being heated in the exchangers E2, E1 as a gas 31.
Un liquide 53 provenant du condenseur de tête C2 de la colonne K3 se vaporise par échange de chaleur avec le gaz 27 dans le condenseur C1 formant le gaz 55 envoyé à l’entrée du compresseur V3.  A liquid 53 from the top condenser C2 of the column K3 vaporizes by heat exchange with the gas 27 in the condenser C1 forming the gas 55 sent to the inlet of the compressor V3.
Le liquide de cuve 21 enrichi en monoxyde de carbone et appauvri en azote est détendu. Ce liquide à 6,5 bars est envoyé à un séparateur de phases dont le liquide sert en partie à refroidir le condenseur C1 . Ainsi, le condenseur de la tête Ci de colonne CO/N2 K2 est refroidi par vaporisation d'au moins une partie du liquide de cuve 33 de la colonne CO/N2 K2 après détente et vaporisation de l’azote liquide 53 à moyenne pression. Le fait de vaporiser ie liquide de cuve 33 après détente permet de réduire considérablement le débit de cycle d’azote à vaporiser dans ie condenseur Ci , ce qui réduit le débit de cycle d’azote et donc la puissance du compresseur de cycle d’azote V1 , V2, V3 The tank liquor 21 enriched in carbon monoxide and depleted of nitrogen is expanded. This liquid at 6.5 bar is sent to a phase separator whose liquid is used in part to cool the condenser C1. Thus, the condenser of the column head CO / N 2 K2 column is cooled by vaporization of at least a portion of the tank liquid 33 of the column CO / N 2 K2 after expansion and vaporization of the liquid nitrogen 53 average pressure. Spraying the tank liquid 33 after expansion makes it possible to considerably reduce the nitrogen cycle flow rate to be vaporized in condenser Ci, which reduces the nitrogen cycle flow rate and therefore the power of the nitrogen cycle compressor V1, V2, V3
Le gaz 31 constitue un produit riche en monoxyde de carbone du procédé. Gas 31 is a carbon monoxide rich product of the process.
La pression d’opération de la colonne de déazotation K2 est d’au moins 7 bars abs, voire 8 bars abs ; la pression d’opération de la colonne de séparation de monoxyde de carbone et de méthane K3 est d’au moins 5 bars abs, voire 6 bars abs. The operating pressure of the denitrogenation column K2 is at least 7 bar abs, or even 8 bar abs; the operating pressure of the separation column of carbon monoxide and methane K3 is at least 5 bar abs, or even 6 bar abs.
Revendications claims
1. Procédé de séparation d’un mélange gazeux comprenant du monoxyde de carbone, de l’azote, de l’hydrogène et du méthane dans lequel : A process for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and methane wherein:
i) On refroidit le mélange dans un échangeur de chaleur (E1 , E2),  i) the mixture is cooled in a heat exchanger (E1, E2),
ii) On sépare le mélange refroidi dans l’échangeur de chaleur par au moins une étape de condensation partielle et/ou de distillation et/ou de lavage afin de former un fluide appauvri en hydrogène contenant du monoxyde de carbone et de l’azote,  ii) separating the cooled mixture in the heat exchanger by at least one partial condensation and / or distillation and / or washing step to form a hydrogen-depleted fluid containing carbon monoxide and nitrogen,
iii) On envoie le fluide appauvri en hydrogène vers une colonne de déazotation (K2) ayant un condenseur de tête (C1 ) et un rebouilleur de cuve (R2) pour produire un gaz enrichi en azote en tête de colonne et un liquide appauvri en azote en cuve de colonne,  iii) The hydrogen-depleted fluid is sent to a denitrogenation column (K2) having a top condenser (C1) and a bottom reboiler (R2) to produce a column-enriched nitrogen enriched gas and a nitrogen-depleted liquid in column vats,
iv) On refroidit le condenseur de la colonne de déazotation au moyen d’un cycle d’azote utilisant un compresseur d’azote (V1 , V2, V3) à au moins un premier étage et une deuxième étage, la pression d’entrée de la première étage étant plus basse que celle du deuxième étage,  iv) The condenser of the denitrogenation column is cooled by means of a nitrogen cycle using a nitrogen compressor (V1, V2, V3) to at least a first stage and a second stage, the inlet pressure of the first floor being lower than that of the second floor,
v) On détend du liquide de cuve (21 ) de la colonne de déazotation, on l’envoie vers le condenseur de tête de la colonne de déazotation pour se vaporiser au moins partiellement par échange de chaleur dans un échangeur de chaleur du condenseur avec le gaz enrichi en azote qui s’en trouve condensé,  v) Expansion tank liquid (21) from the denitrogenation column is sent to the top condenser of the denitrogenation column to vaporize at least partially by heat exchange in a heat exchanger of the condenser with the gas enriched in nitrogen which is condensed,
vi) On vaporise également dans l’échangeur de chaleur du condenseur de l’azote liquide (53) provenant du cycle d’azote et on renvoie l’azote vaporisé (55) dans l’échangeur de chaleur à l’entrée du deuxième étage (V3) du compresseur d’azote et  vi) The liquid nitrogen condenser (53) from the nitrogen cycle is also vaporized in the heat exchanger and the vaporized nitrogen (55) is returned to the heat exchanger at the inlet of the second stage. (V3) of the nitrogen compressor and
a) on envoie du liquide de cuve (33) de la colonne de déazotation (K2) vers une colonne de séparation de monoxyde de carbone et de méthane (K3) comprenant un condenseur de tête (C2) qui est un vaporiseur à bain placé dans un bain de liquide ou  a) the bottom liquid (33) of the denitrogenization column (K2) is sent to a carbon monoxide and methane separation column (K3) comprising a top condenser (C2) which is a bath vaporizer placed in a a bath of liquid or
b) la séparation de l’étape ii) comprend une étape de distillation dans une colonne (K3) de séparation de monoxyde de carbone et de méthane pour séparer un débit appauvri en méthane d’un débit enrichi en méthane et au moins une partie du débit appauvri en méthane (41 ) constitue le fluide appauvri  b) the separation of step ii) comprises a distillation step in a column (K3) for separating carbon monoxide and methane to separate a methane-depleted flowrate from a methane-enriched flow and at least a part of the depleted flow rate of methane (41) is the depleted fluid

Claims

en hydrogène alimentant la colonne de déazotation, la colonne de séparation de monoxyde de carbone et de méthane (K3) comprenant un condenseur de tête (C2) qui est un vaporiseur à bain placé dans un bain de liquide le bain de liquide de a) ou b) étant alimenté par de l’azote liquide (61 ,63,65) provenant du cycle d’azote (59).  hydrogen supplying the denitrogenation column, the carbon monoxide and methane separation column (K3) comprising a top condenser (C2) which is a bath vaporizer placed in a bath of liquid the liquid bath of a) or b) being fed with liquid nitrogen (61, 63, 65) from the nitrogen cycle (59).
2. Procédé selon la revendication 1 dans lequel on envoie de l’azote liquide (53) du condenseur de tête (C2) de la colonne de séparation de monoxyde de carbone et de méthane se vaporiser dans le condenseur de tête (C1 ) de la colonne de déazotation. 2. Method according to claim 1 wherein the liquid nitrogen (53) of the head condenser (C2) of the carbon monoxide and methane separation column is vaporized in the head condenser (C1) of the denitration column.
3. Procédé selon l’une des revendications précédentes dans lequel on sépare le mélange refroidi dans l’échangeur de chaleur (E1 , E2) par au moins une étape de condensation partielle afin de former un gaz appauvri en hydrogène (5), on envoie le gaz appauvri en hydrogène à un niveau intermédiaire d’une colonne d’épuisement (K1 ) ayant un rebouilleur de cuve (R1 ) et on envoie du liquide de cuve (19) de la colonne d’épuisement vers une colonne de déazotation (K2) selon le cas a) ou vers la colonne de séparation de monoxyde de carbone et de méthane (K3) selon le cas b). 3. Method according to one of the preceding claims wherein the cooled mixture is separated in the heat exchanger (E1, E2) by at least one partial condensation step to form a hydrogen-depleted gas (5), it sends the hydrogen-depleted gas at an intermediate level of a depletion column (K1) having a bottom reboiler (R1) and the bottom liquid (19) is sent from the depletion column to a denitrogenation column (K2 ) as applicable (a) or to the carbon monoxide and methane separation column (K3) as the case may be (b).
4. Procédé selon l’une des revendications précédentes dans lequel on réchauffe le rebouilleur (R1 ) de la colonne d’épuisement (K1 ) et/ou le rebouilleur (R3) de la colonne de séparation de monoxyde de carbone et de méthane (K2) avec au moins d’une partie du mélange gazeux (1 ). 4. Method according to one of the preceding claims wherein the reboiler (R1) of the exhaustion column (K1) and / or the reboiler (R3) of the carbon monoxide and methane separation column (K2) are heated. ) with at least a portion of the gaseous mixture (1).
5. Procédé selon l’une des revendications précédentes dans lequel la pression d’opération de la colonne de déazotation (K2) est d’au moins 7 bars abs, voire 8 bars abs et/ou la pression d’opération de la colonne de séparation de monoxyde de carbone et de méthane (K3) est d’au moins 5 bars abs, voire 6 bars abs. 5. Method according to one of the preceding claims wherein the operating pressure of the denitrogenation column (K2) is at least 7 bar abs or 8 bar abs and / or the operating pressure of the column of The separation of carbon monoxide and methane (K3) is at least 5 bar abs, or even 6 bar abs.
6. Procédé selon l’une des revendications précédentes dans lequel le condenseur de tête (C2) de la colonne CO/CH4 (K3) est refroidi uniquement par de l’azote de cycle. 6. Method according to one of the preceding claims wherein the top condenser (C2) of the column CO / CH4 (K3) is cooled solely by nitrogen cycle.
7. Procédé selon l’une des revendications précédentes dans lequel on réchauffe le rebouilleur (R2) de la colonne de déazotation (K2) au moyen de l’azote de cycle. 7. Method according to one of the preceding claims wherein the reboiler (R2) of the denitrogenation column (K2) is heated by means of the ring nitrogen.
8. Procédé selon la revendication 7 dans lequel l’azote utilisé pour réchauffer le rebouilleur (R2) de la colonne de déazotation (K2) est à la pression maximale du cycle azote. The process of claim 7 wherein the nitrogen used to heat the reboiler (R2) of the denitrogenation column (K2) is at the maximum pressure of the nitrogen cycle.
9. Procédé selon l’une des revendications précédentes dans lequel l’azote envoyé au bain du condenseur (C2) de la colonne CO/CH4 (K3) est condensé à la pression maximale du cycle azote. 9. Method according to one of the preceding claims wherein the nitrogen sent to the bath of the condenser (C2) of the column CO / CH4 (K3) is condensed at the maximum pressure of the nitrogen cycle.
10. Procédé selon l’une des revendications précédentes dans lequel la pression d’opération de la colonne de séparation de monoxyde de carbone et de méthane est d’au moins 5 bars abs, voire 6 bars abs. 10. Method according to one of the preceding claims wherein the operating pressure of the carbon monoxide and methane separation column is at least 5 bar abs, or 6 bar abs.
11. Appareil de séparation d’un mélange gazeux comprenant du monoxyde de carbone, de l’azote, de l’hydrogène et du méthane comprenant un échangeur de chaleur (E1 , E2) pour refroidir le mélange, des moyens de séparation du mélange refroidi dans l’échangeur de chaleur par au moins une étape de condensation partielle et/ou de distillation et/ou de lavage afin de former un fluide appauvri en hydrogène contenant du monoxyde de carbone et de l’azote, une colonne de déazotation (K2) ayant un condenseur de tête (C1 ) et éventuellement un rebouilleur de cuve (R2), une conduite pour envoyer le fluide appauvri en hydrogène vers la colonne de déazotation pour produire un gaz enrichi en azote en tête de colonne et un liquide appauvri en azote en cuve de colonne, un cycle d’azote utilisant un compresseur d’azote (V1 , V2, V3) à au moins un premier étage et une deuxième étage, la pression d’entrée de la première étage étant plus basse que celle du deuxième étage, des moyens pour envoyer du liquide du cycle d’azote vers le condenseur (C1 ) de la colonne de déazotation, des moyens pour détendre du liquide de cuve (21 ) de la colonne de déazotation, des moyens pour envoyer le liquide détendu vers le condenseur de tête de la colonne de déazotation pour se vaporiser au moins partiellement par échange de chaleur dans un échangeur de chaleur du condenseur avec le gaz enrichi en azote qui s’en trouve condensé, des moyens pour envoyer de l’azote vaporisé (55) dans l’échangeur de chaleur du condenseur à l’entrée du deuxième étage (V3) du compresseur d’azote, une colonne de séparation de monoxyde de carbone et de méthane (K3) comprenant un condenseur de tête (C2) qui est un vaporiseur à bain placé dans un bain de liquide, Apparatus for separating a gaseous mixture comprising carbon monoxide, nitrogen, hydrogen and methane comprising a heat exchanger (E1, E2) for cooling the mixture, means for separating the cooled mixture in the heat exchanger by at least one partial condensation and / or distillation and / or washing step to form a hydrogen-depleted fluid containing carbon monoxide and nitrogen, a denitrogenation column (K2) having a head condenser (C1) and optionally a bottom reboiler (R2), a conduit for supplying the hydrogen depleted fluid to the denitrogenation column to produce a nitrogen enriched gas at the head of the column and a nitrogen-depleted liquid in column vessel, a nitrogen cycle using a nitrogen compressor (V1, V2, V3) to at least a first stage and a second stage, the inlet pressure of the first stage being lower than that of the second stage , means s to send liquid from the nitrogen cycle to the condenser (C1) of the denitrogenation column, means for expanding tank liquid (21) from the denitrogenation column, means for sending the liquid expanded to the top condenser of the denitrogenation column to vaporize at least partially by heat exchange in a condenser heat exchanger with the nitrogen-enriched gas condensed therein, means for sending vaporized nitrogen (55) in the condenser heat exchanger at the inlet of the second stage (V3) of the nitrogen compressor, a carbon monoxide and methane separation column (K3) comprising a top condenser (C2) which is a bath vaporizer placed in a bath of liquid,
a) des moyens pour envoyer le liquide de cuve (33) de la colonne de déazotation à la colonne de séparation de monoxyde de carbone et de méthane ou b) la colonne de séparation de monoxyde de carbone et de méthane des moyens faisant partie des moyens de séparation du mélange refroidi dans l’échangeur de chaleur par au moins une étape de distillation l’appareil comprenant également des moyens pour envoyer de l’azote liquide (61 ,63,65) provenant du cycle d’azote vers le condenseur de tête de la colonne de séparation de monoxyde de carbone et de méthane.  a) means for sending the vessel liquid (33) from the denitrogenation column to the carbon monoxide and methane separation column; or b) the carbon monoxide and methane separation column of the means forming part of the means separating the cooled mixture into the heat exchanger by at least one distillation step the apparatus further comprising means for supplying liquid nitrogen (61, 63, 65) from the nitrogen cycle to the overhead condenser of the carbon monoxide and methane separation column.
12. Appareil selon la revendication 11 comprenant des moyens pour envoyer de l’azote liquide (53) du condenseur de tête (C2) de la colonne de séparation de monoxyde de carbone et de méthane (K3) vers le condenseur de tête (C1 ) de la colonne de déazotation (K2). 12. Apparatus according to claim 11 comprising means for sending liquid nitrogen (53) from the top condenser (C2) of the carbon monoxide and methane separation column (K3) to the top condenser (C1). of the denitrogenation column (K2).
13. Appareil selon l’une des revendications précédentes 11 ou 12 comprenant au moins un séparateur de phase (S1 , S3) pour séparer le mélange refroidi dans l’échangeur de chaleur par une étape de condensation partielle afin de former un gaz appauvri en hydrogène, une colonne d’épuisement (K1 ) et des moyens pour envoyer le gaz appauvri en hydrogène à un niveau intermédiaire de la colonne d’épuisement. 13. Apparatus according to one of the preceding claims 11 or 12 comprising at least one phase separator (S1, S3) for separating the cooled mixture in the heat exchanger by a partial condensation step to form a gas depleted in hydrogen , a depletion column (K1) and means for supplying the hydrogen-depleted gas at an intermediate level of the depletion column.
EP18833939.4A 2017-12-14 2018-12-13 Method and apparatus for the cryogenic separation of a synthesis gas containing a nitrogen separation step Pending EP3724573A1 (en)

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