WO2018020091A1 - Method and apparatus for scrubbing at cryogenic temperature in order to produce a mixture of hydrogen and nitrogen - Google Patents

Method and apparatus for scrubbing at cryogenic temperature in order to produce a mixture of hydrogen and nitrogen Download PDF

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Publication number
WO2018020091A1
WO2018020091A1 PCT/FR2017/051798 FR2017051798W WO2018020091A1 WO 2018020091 A1 WO2018020091 A1 WO 2018020091A1 FR 2017051798 W FR2017051798 W FR 2017051798W WO 2018020091 A1 WO2018020091 A1 WO 2018020091A1
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Prior art keywords
nitrogen
gas
hydrogen
heat exchanger
mixture
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PCT/FR2017/051798
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French (fr)
Inventor
Jean Billy
Antoine Hernandez
Marie-Pascal Victor
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L'air Liquide, Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude
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Publication of WO2018020091A1 publication Critical patent/WO2018020091A1/en

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J3/00—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification
    • F25J3/02—Processes or apparatus for separating the constituents of gaseous or liquefied gaseous mixtures involving the use of liquefaction or solidification by rectification, i.e. by continuous interchange of heat and material between a vapour stream and a liquid stream
    • F25J3/0204—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
    • F25J3/0219—Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
    • C01B3/025—Preparation or purification of gas mixtures for ammonia synthesis
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/506—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification at low temperatures
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B3/00—Hydrogen; Gaseous mixtures containing hydrogen; Separation of hydrogen from mixtures containing it; Purification of hydrogen
    • C01B3/50—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification
    • C01B3/52—Separation of hydrogen or hydrogen containing gases from gaseous mixtures, e.g. purification by contacting with liquids; Regeneration of used liquids
    • 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
    • F25J3/0276—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 H2/N2 mixtures, i.e. of ammonia synthesis gas
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0415—Purification by absorption in liquids
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/046—Purification by cryogenic separation
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B2203/00—Integrated processes for the production of hydrogen or synthesis gas
    • C01B2203/04—Integrated processes for the production of hydrogen or synthesis gas containing a purification step for the hydrogen or the synthesis gas
    • C01B2203/0465—Composition of the impurity
    • C01B2203/047—Composition of the impurity the impurity being 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
    • 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
    • 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
    • F25J2205/30—Processes or apparatus using other separation and/or other processing means using a washing, e.g. "scrubbing" or bubble column for purification purposes
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2205/00—Processes or apparatus using other separation and/or other processing means
    • F25J2205/60—Processes or apparatus using other separation and/or other processing means using adsorption on solid adsorbents, e.g. by temperature-swing adsorption [TSA] at the hot or cold end
    • F25J2205/66—Regenerating the adsorption vessel, e.g. kind of reactivation gas
    • 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
    • F25J2210/20—H2/N2 mixture, i.e. synthesis gas for or purge gas from ammonia synthesis
    • 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
    • F25J2215/00—Processes characterised by the type or other details of the product stream
    • F25J2215/02—Mixing or blending of fluids to yield a certain product
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2220/00—Processes or apparatus involving steps for the removal of impurities
    • F25J2220/02—Separating impurities in general from the feed stream
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2240/00—Processes or apparatus involving steps for expanding of process streams
    • F25J2240/02—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream
    • F25J2240/12—Expansion of a process fluid in a work-extracting turbine (i.e. isentropic expansion), e.g. of the feed stream the fluid being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2245/00—Processes or apparatus involving steps for recycling of process streams
    • F25J2245/42—Processes or apparatus involving steps for recycling of process streams the recycled stream being nitrogen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25J—LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS OR LIQUEFIED GASEOUS MIXTURES BY PRESSURE AND COLD TREATMENT OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE
    • F25J2270/00—Refrigeration techniques used
    • F25J2270/14—External refrigeration with work-producing gas expansion loop

Definitions

  • the present invention relates to a cryogenic temperature washing method and apparatus for producing a mixture of hydrogen and nitrogen.
  • a mixture of hydrogen and nitrogen is frequently used as the feed gas for ammonia synthesis.
  • a washing unit with a liquid solvent to remove most of the acid gases contained in the synthesis gas.
  • cryogenic separation unit called cold box for the production of hydrogen and nitrogen mixture with a ratio defined between hydrogen and nitrogen.
  • the gasification pressures may vary between 20 bar and 65 bar but generally are between 30 and 60 bar.
  • the synthesis gas comprises a mixture at these high pressures containing the following compounds: H 2 , CO, CH, and optionally N 2 and Ar.
  • This process makes it possible to produce a mixture H 2 / N 2 under pressure with good purity.
  • the synthesis gas is cooled to a temperature between -180 ° C and -190 ° C generally.
  • the remaining vapor phase of this thermodynamic equilibrium reached is treated in a nitrogen washing column where liquid nitrogen is injected at the top of the column, which makes it possible to lower the content of CH 4 and CO in the vapor produced. at the top of the column washing a mixture of hydrogen and nitrogen with a very low level of CH 4 and / or CO (some ppm), corresponding to the need of the ammonia production unit.
  • the liquid containing the impurities and a part of the nitrogen coming from washing is held at low pressure and heated to ambient temperature for use in the fuel system as a fuel.
  • the known processes use liquid nitrogen supplied and coming from an external source, for example an air separation apparatus, to complete the refrigeration balance of the unit and thus keep the process cold.
  • the liquid nitrogen can be injected directly at the cold end of the exchanger of the main exchange line or be mixed with the gas produced at the top of the washing column before the exchanger.
  • the invention proposes to provide the frigories to complete the refrigeration balance of the unit by expansion of nitrogen through a turbine.
  • DE3925662 describes a process in which nitrogen is divided into two parts to be liquefied and sent to one wash column for one part and to be expanded in one turbine for the other part. Most of the relaxed nitrogen serves then in a process of separating the bottom liquid from the column.
  • the nitrogen washing process utilizes nitrogen gas supplied at high pressure from the ASU.
  • the idea is to use some of this nitrogen gas, after cooling in the exchange line, and relax it through a turbine. All the nitrogen leaving the turbine is heated and then serves as the regeneration gas of the water purification unit and / or CO 2 of the synthesis gas or be sent to the absorption unit, for example to the methanol, called Rectisol ® for the stripping column. This reduces the total nitrogen consumption of the industrial complex.
  • a cryogenic temperature washing process for producing a mixture of hydrogen and nitrogen in which:
  • a gaseous mixture containing at least hydrogen, methane and carbon monoxide and methanol and / or water and / or carbon dioxide is purified to methanol and / or water and / or adsorption carbon dioxide in an adsorption unit.
  • the purified gas mixture is cooled in a heat exchanger to a cryogenic temperature and sent to a washing column.
  • a nitrogen-rich liquid is sent to the top of the wash column.
  • a gas containing hydrogen and nitrogen is withdrawn from the top of the wash column and reheated to form the mixture of hydrogen and nitrogen.
  • a flow of nitrogen gas is cooled in the heat exchanger and divided into two parts, a first part of the nitrogen is liquefied to form the nitrogen-rich liquid and a second part of the nitrogen is expanded in a turbine, characterized in that all the nitrogen expanded in the turbine is heated in the heat exchanger to form an auxiliary flow of nitrogen, and
  • At least a portion of the auxiliary nitrogen flow serves to regenerate the adsorption unit without having been compressed or liquefied after expansion in the turbine or
  • the gaseous mixture is from an absorption unit and at least a portion of the auxiliary nitrogen flow serves as a stripping gas in a stripping column of the absorption unit.
  • the gaseous mixture contains nitrogen and / or argon and / or water and / or carbon dioxide and / or methanol,
  • a third part of the nitrogen is mixed with the overhead gas of the washing column to adjust the hydrogen / nitrogen ratio
  • the nitrogen gas comes from an air separation apparatus, the nitrogen gas from the apparatus is compressed in a nitrogen compressor at a pressure of not more than 35 bar upstream of the heat exchanger,
  • the first part of the nitrogen is liquefied in the heat exchanger, the expanded nitrogen gas heats up to the hot end of the heat exchanger,
  • the flow of nitrogen gas is divided into only two parts, the first part of the nitrogen is liquefied to form the nitrogen-rich liquid and the second part of the nitrogen is expanded in the turbine,
  • a cryogenic temperature washing apparatus for producing a mixture of hydrogen and nitrogen comprising a unit for purifying a gaseous mixture containing at least hydrogen, methane and hydrogen. carbon monoxide in methanol and / or water and / or carbon dioxide by adsorption, a heat exchanger, a pipe for sending the purified gas mixture containing at least hydrogen, methane and carbon monoxide to cool in the heat exchanger to a cryogenic temperature, a washing column, a conduit for feeding the cooled gas mixture into the heat exchanger to the washing column, a conduit for delivering a nitrogen-rich liquid at the top of the the washing column, a pipe for withdrawing a gas containing hydrogen and nitrogen from the head of the washing column, the pipe for withdrawing the gas being connected to the heat exchanger for allowing re that the mixture of hydrogen and nitrogen is heated therein characterized in that it comprises means for sending a flow of nitrogen gas to cool in the heat exchanger, means for liquefying a first portion of the
  • the apparatus comprising an absorption treatment unit which produces the gaseous mixture containing hydrogen and carbon monoxide comprising the stripping column.
  • the apparatus does not comprise means for liquefying the nitrogen expanded in the turbine.
  • the apparatus does not include a compressor of nitrogen expanded in the turbine.
  • the apparatus comprises a single low temperature separation column for separating the purified gas mixture or a fluid derived from the purified gas mixture.
  • the apparatus comprises a pipe for sending an additional flow of nitrogen to the adsorption unit for regeneration.
  • an apparatus for producing a mixture of hydrogen and nitrogen comprising a washing apparatus as described above and an absorption treatment unit which produces the mixture.
  • gas containing hydrogen and carbon monoxide comprising a stripping column and means for sending at least a portion of the auxiliary nitrogen flow to the stripping column as a stripping gas.
  • a synthesis gas containing hydrogen, methane and carbon monoxide is treated in an absorption unit 1, for example of the methanol Rectisol® type, using at least one stripping column.
  • the product gas 3 containing hydrogen, nitrogen, methane and carbon monoxide and water and / or carbon dioxide and / or methanol is purified to methanol and / or water and and / or carbon dioxide, if one of these impurities is present, in an adsorption unit 5 to produce a purified gas 7.
  • the purified gas is cooled in a heat exchanger 9 to a temperature of between -180 ° C and -190 ° C to form a cooled gas 1 1.
  • the cooled gas 11 is sent to the bottom of a washing column 13.
  • the washing column 13 is fed at the top with liquid nitrogen 31 produced by cooling a portion of the nitrogen gas 25 from an air separation apparatus into a heat exchanger 9A and then into the heat exchanger 9.
  • the column liquid 15 of the carbon monoxide enriched column 13 and depleted of hydrogen is expanded in a valve and sent to a phase separator 1 7.
  • the product gas 19 is heated and the liquid produced 21 heats up and vaporizes in the heat exchanger 9 and is mixed to form a flow 23 which heats up in the heat exchanger 9A to form a waste gas.
  • This expanded gas 44 constitutes an auxiliary gas and can serve as a regeneration gas 47 for the adsorption unit 5 and / or as a stripping gas for a stripping column of the absorption unit 1.
  • Another part of the nitrogen 33 cools in the exchangers 9A and 9 and is mixed with the overhead gas 35 of the washing column 13 to obtain a desired H 2 / N 2 ratio in the gas 37.
  • the overhead gas 35 was warmed from -190 ° C to -180 ° C in the exchanger 9 (not shown) before being mixed with the gas 33.
  • the formed gas 37 is divided in two downstream of the exchange 9 and in upstream of the exchanger 9A, a flow 42 being sent to the absorption unit for heating and a flow 39 heating in the exchanger 9A.
  • the mixture 43 formed of flow 42, 39 is the mixture of hydrogen and nitrogen which is the product of the process.
  • a nitrogen flow rate 49 may be required to regenerate the adsorption unit 5.
  • the table compares the process according to the invention with a turbine and the process without a turbine. Even if additional high pressure nitrogen from the air separation is required, the nitrogen pressure is lower and the liquid nitrogen consumption is zero according to the invention. The additional nitrogen used is for other uses. The lower pressure and the reduction in liquid nitrogen consumption can reduce energy consumption by around 8%. With turbine Without turbine

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Inorganic Chemistry (AREA)
  • Separation By Low-Temperature Treatments (AREA)

Abstract

The invention relates to a method for scrubbing at cryogenic temperature in order to produce a mixture of hydrogen and nitrogen, in which a gaseous mixture (3, 11) containing at least hydrogen, methane and carbon monoxide is cooled in a heat exchanger (9A, 9) to a cryogenic temperature and sent into a scrubbing column (13), a nitrogen-rich liquid (31) is sent to the head of the scrubbing column, a gas containing hydrogen and nitrogen (35) is drawn from the head of the scrubbing column and heated to form the mixture of hydrogen and nitrogen, and a flow of gaseous nitrogen (25) is cooled in the heat exchanger and divided into two portions: a first portion of the nitrogen is liquefied to form the nitrogen-rich liquid and a second portion (27) of the nitrogen is expanded in a turbine (41), and the expanded nitrogen is reheated in the heat exchanger in order to form an auxiliary nitrogen flow (44).

Description

Procédé et appareil de lavage à température cryogénique pour la production d'un mélange d'hydrogène et d'azote  Method and apparatus for cryogenic temperature washing for the production of a mixture of hydrogen and nitrogen
La présente invention est relative à un procédé et un appareil de lavage à température cryogénique pour la production d'un mélange d'hydrogène et d'azote. The present invention relates to a cryogenic temperature washing method and apparatus for producing a mixture of hydrogen and nitrogen.
Un mélange d'hydrogène et d'azote est fréquemment utilisé comme gaz d'alimentation pour la synthèse d'ammoniac.  A mixture of hydrogen and nitrogen is frequently used as the feed gas for ammonia synthesis.
Les unités de production de mélanges d'hydrogène et d'azote peuvent être séparées en deux parties :  The units for the production of hydrogen and nitrogen mixtures can be separated into two parts:
- génération du gaz de synthèse (mélange contenant H2, CO, CH , CO2, Ar et N2 essentiellement). Parmi les diverses voies industrielles de production de gaz de synthèse, la gazéification de charbon est une méthode très développée ces dernières années. La conception de cette unité qui comprend un réacteur de gazéification du charbon avec de l'oxygène est basée sur la production en hydrogène requises. - Generation of the synthesis gas (mixture containing H 2 , CO, CH, CO 2 , Ar and N 2 essentially). Of the various synthetic gas production routes, coal gasification is a very advanced method in recent years. The design of this unit which includes a coal gasification reactor with oxygen is based on the required hydrogen production.
- purification du gaz de synthèse.  - purification of the synthesis gas.
On retrouve :  We find :
une unité de lavage à 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.
une unité de séparation par voie cryogénique dite boite froide pour la production de mélange hydrogène et azote avec un rapport défini entre l'hydrogène et l'azote.  a cryogenic separation unit called cold box for the production of hydrogen and nitrogen mixture with a ratio defined between hydrogen and nitrogen.
Les pressions de gazéification peuvent varier entre 20 bars et 65 bars mais généralement se trouvent entre 30 et 60 bars. Le gaz de synthèse comprend un mélange à ces hautes pressions contenant les composés suivants : H2, CO, CH , et éventuellement N2 et Ar. The gasification pressures may vary between 20 bar and 65 bar but generally are between 30 and 60 bar. The synthesis gas comprises a mixture at these high pressures containing the following compounds: H 2 , CO, CH, and optionally N 2 and Ar.
Pour produire d'un mélange H2/N2 contenant de très faibles teneurs en CH et/ou en CO (notamment pour la production d'ammoniac), le procédé le plus adapté est le procédé par lavage à l'azote. To produce an H 2 / N 2 mixture containing very low levels of CH and / or CO (especially for the production of ammonia), the most suitable method is the nitrogen washing process.
Ce procédé permet de produire un mélange H2/N2 sous pression avec une bonne pureté. Le gaz de synthèse est refroidi à une température entre -180°C et -190°C généralement. La phase vapeur restante de cet équilibre thermodynamique atteint est traitée dans une colonne de lavage à l'azote où on injecte de l'azote liquide en tête de colonne, ce qui permet d'abaisser la teneur en CH4 et CO dans la vapeur produite en tête de colonne de lavage d'un mélange d'hydrogène et d'azote avec un très faible niveau en CH4 et/ou en CO (quelque ppm), correspondant au besoin de l'unité de production d'ammoniac. This process makes it possible to produce a mixture H 2 / N 2 under pressure with good purity. The synthesis gas is cooled to a temperature between -180 ° C and -190 ° C generally. The remaining vapor phase of this thermodynamic equilibrium reached is treated in a nitrogen washing column where liquid nitrogen is injected at the top of the column, which makes it possible to lower the content of CH 4 and CO in the vapor produced. at the top of the column washing a mixture of hydrogen and nitrogen with a very low level of CH 4 and / or CO (some ppm), corresponding to the need of the ammonia production unit.
En cuve de colonne, le liquide contenant les impuretés et une partie de l'azote venant de lavage est détenu à faible pression et réchauffé à température ambiant pour être utilisé dans le réseau de carburant comme combustible.  In column vat, the liquid containing the impurities and a part of the nitrogen coming from washing is held at low pressure and heated to ambient temperature for use in the fuel system as a fuel.
Les procédés connus utilisent de l'azote liquide mis à disposition et provenant d'une source externe, par exemple un appareil de séparation d'air, pour boucler le bilan frigorifique de l'unité et ainsi maintenir en froid le procédé. L'azote liquide peut être injecté directement au bout froid de l'échangeur de la ligne d'échange principale ou bien être mélangé avec le gaz produit en tête de la colonne de lavage avant l'échangeur.  The known processes use liquid nitrogen supplied and coming from an external source, for example an air separation apparatus, to complete the refrigeration balance of the unit and thus keep the process cold. The liquid nitrogen can be injected directly at the cold end of the exchanger of the main exchange line or be mixed with the gas produced at the top of the washing column before the exchanger.
L'invention propose d'apporter les frigories pour boucler le bilan frigorifique de l'unité par détente d'azote à travers une turbine.  The invention proposes to provide the frigories to complete the refrigeration balance of the unit by expansion of nitrogen through a turbine.
Ainsi, cela permet de ne pas avoir à utiliser de l'azote liquide venant des unités extérieures à l'unité de lavage à l'azote.  Thus, this makes it possible not to use liquid nitrogen from the units outside the nitrogen washing unit.
Ceci est particulièrement intéressant lorsque l'appareil de séparation d'air (ASU) a déjà été dimensionné et alors il n'est pas possible, sans investissement majeur, de produire de l'azote liquide. Dans d'autres cas l'ASU est localisé loin de l'unité de lavage à l'azote. L'invention permet ainsi que limiter les interfaces entre l'ASU et l'unité de lavage à l'azote.  This is particularly interesting when the air separation apparatus (ASU) has already been sized and then it is not possible, without major investment, to produce liquid nitrogen. In other cases the ASU is located far from the nitrogen wash unit. The invention thus makes it possible to limit the interfaces between the ASU and the nitrogen washing unit.
DE3925662 décrit un procédé dans lequel de l'azote est divisé en deux parties pour être liquéfiée et envoyée à une colonne de lavage pour une partie et pour être détendue dans une turbine pour l'autre partie. La plupart de l'azote sert détendu sert ensuite dans un procédé de séparation du liquide de cuve de la colonne.  DE3925662 describes a process in which nitrogen is divided into two parts to be liquefied and sent to one wash column for one part and to be expanded in one turbine for the other part. Most of the relaxed nitrogen serves then in a process of separating the bottom liquid from the column.
Le procédé de lavage à l'azote utilise de l'azote gazeux fourni à haute pression de l'unité ASU.  The nitrogen washing process utilizes nitrogen gas supplied at high pressure from the ASU.
L'idée est d'utiliser une partie de cet azote gazeux, après refroidissement dans la ligne d'échange, et la détendre à travers une turbine. Tout l'azote sortant de la turbine est réchauffé et ensuite sert comme gaz de régénération de l'unité d'épuration en eau et/ou CO2 du gaz de synthèse ou bien être envoyé vers l'unité d'absorption, par exemple au méthanol, dite Rectisol ® pour la colonne de strippage. Ceci réduit la consommation totale d'azote du complexe industriel. The idea is to use some of this nitrogen gas, after cooling in the exchange line, and relax it through a turbine. All the nitrogen leaving the turbine is heated and then serves as the regeneration gas of the water purification unit and / or CO 2 of the synthesis gas or be sent to the absorption unit, for example to the methanol, called Rectisol ® for the stripping column. This reduces the total nitrogen consumption of the industrial complex.
Selon un objet de l'invention, il est prévu un procédé de lavage à température cryogénique pour produire un mélange d'hydrogène et d'azote dans lequel :  According to one object of the invention, there is provided a cryogenic temperature washing process for producing a mixture of hydrogen and nitrogen in which:
i) Un mélange gazeux contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone ainsi que du méthanol et/ou de l'eau et/ou du dioxyde de carbone est épuré en méthanol et/ou eau et/ou en dioxyde de carbone par adsorption dans une unité d'adsorption.  (i) A gaseous mixture containing at least hydrogen, methane and carbon monoxide and methanol and / or water and / or carbon dioxide is purified to methanol and / or water and / or adsorption carbon dioxide in an adsorption unit.
ii) Le mélange gazeux épuré est refroidi dans un échangeur de chaleur jusqu'à une température cryogénique et envoyé dans une colonne de lavage.  ii) The purified gas mixture is cooled in a heat exchanger to a cryogenic temperature and sent to a washing column.
iii) Un liquide riche en azote est envoyé en tête de la colonne de lavage. iv) Un gaz contenant de l'hydrogène et de l'azote est soutiré de la tête de la colonne de lavage et réchauffé pour constituer le mélange d'hydrogène et d'azote. v) Un débit d'azote gazeux est refroidi dans l'échangeur de chaleur et divisé en deux parties, une première partie de l'azote est liquéfiée pour constituer le liquide riche en azote et une deuxième partie de l'azote est détendue dans une turbine, caractérisé en ce que tout l'azote détendu dans la turbine est réchauffé dans l'échangeur de chaleur pour constituer un débit auxiliaire d'azote, et  iii) A nitrogen-rich liquid is sent to the top of the wash column. iv) A gas containing hydrogen and nitrogen is withdrawn from the top of the wash column and reheated to form the mixture of hydrogen and nitrogen. v) A flow of nitrogen gas is cooled in the heat exchanger and divided into two parts, a first part of the nitrogen is liquefied to form the nitrogen-rich liquid and a second part of the nitrogen is expanded in a turbine, characterized in that all the nitrogen expanded in the turbine is heated in the heat exchanger to form an auxiliary flow of nitrogen, and
vi) Au moins une partie du débit auxiliaire d'azote sert à régénérer l'unité d'adsorption, sans avoir été comprimé ou liquéfié après la détente dans la turbine ou  vi) At least a portion of the auxiliary nitrogen flow serves to regenerate the adsorption unit without having been compressed or liquefied after expansion in the turbine or
vii) Le mélange gazeux provient d'une unité d'absorption et au moins une partie du débit auxiliaire d'azote sert comme gaz de strippage dans une colonne de strippage de l'unité d'absorption.  vii) The gaseous mixture is from an absorption unit and at least a portion of the auxiliary nitrogen flow serves as a stripping gas in a stripping column of the absorption unit.
Selon d'autres aspects facultatifs :  According to other optional aspects:
le mélange gazeux contient de l'azote et/ou de l'argon et/ou de l'eau et/ou du dioxyde de carbone et/ou du méthanol,  the gaseous mixture contains nitrogen and / or argon and / or water and / or carbon dioxide and / or methanol,
une troisième partie de l'azote est mélangé avec le gaz de tête de la colonne de lavage pour ajuster le rapport hydrogène/azote,  a third part of the nitrogen is mixed with the overhead gas of the washing column to adjust the hydrogen / nitrogen ratio,
l'azote gazeux provient d'un appareil de séparation d'air, l'azote gazeux provenant de l'appareil est comprimé dans un compresseur d'azote à une pression d'au plus 35 bars en amont de l'échangeur de chaleur, the nitrogen gas comes from an air separation apparatus, the nitrogen gas from the apparatus is compressed in a nitrogen compressor at a pressure of not more than 35 bar upstream of the heat exchanger,
aucune partie de l'azote gazeux détendu n'est renvoyée au compresseur d'azote,  no part of the expanded nitrogen gas is returned to the nitrogen compressor,
la première partie de l'azote est liquéfié dans l'échangeur de chaleur, l'azote gazeux détendu se réchauffe jusqu'au bout chaud de l'échangeur de chaleur,  the first part of the nitrogen is liquefied in the heat exchanger, the expanded nitrogen gas heats up to the hot end of the heat exchanger,
le débit d'azote gazeux est divisé en seulement deux parties, dont la première partie de l'azote est liquéfiée pour constituer le liquide riche en azote et la deuxième partie de l'azote est détendue dans la turbine,  the flow of nitrogen gas is divided into only two parts, the first part of the nitrogen is liquefied to form the nitrogen-rich liquid and the second part of the nitrogen is expanded in the turbine,
-un débit d'azote additionnel sert à régénérer l'unité d'adsorption.  an additional nitrogen flow is used to regenerate the adsorption unit.
Selon un autre objet de l'invention, il est prévu un appareil de lavage à température cryogénique pour produire un mélange d'hydrogène et d'azote comprenant une unité pour épurer un mélange gazeux contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone en méthanol et/ou en eau et/ou en dioxyde de carbone par adsorption, un échangeur de chaleur, une conduite pour envoyer le mélange gazeux épuré contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone se refroidir dans l'échangeur de chaleur jusqu'à une température cryogénique, une colonne de lavage, une conduite pour envoyer le mélange gazeux refroidi dans l'échangeur de chaleur à la colonne de lavage, une conduite pour envoyer un liquide riche en azote en tête de la colonne de lavage, une conduite pour soutirer un gaz contenant de l'hydrogène et de l'azote de la tête de la colonne de lavage, la conduite pour soutirer le gaz étant reliée à l'échangeur de chaleur pour permettre que le mélange d'hydrogène et d'azote s'y réchauffé caractérisé en ce qu'il comprend des moyens pour envoyer un débit d'azote gazeux se refroidir dans l'échangeur de chaleur, des moyens pour liquéfier une première partie du débit d'azote refroidi et pour l'envoyer à la conduite pour envoyer un liquide riche en azote en tête de la colonne de lavage, une turbine, une conduite pour envoyer une deuxième partie du débit d'azote refroidi à la turbine, une conduite pour envoyer toute la deuxième partie d'azote détendue dans la turbine se réchauffer dans l'échangeur de chaleur et une conduite pour sortir la deuxième partie d'azote réchauffée dans l'échangeur de chaleur, jusqu'au bout chaud de celui-ci, pour constituer un débit auxiliaire d'azote, cette conduite étant reliée : According to another object of the invention, there is provided a cryogenic temperature washing apparatus for producing a mixture of hydrogen and nitrogen comprising a unit for purifying a gaseous mixture containing at least hydrogen, methane and hydrogen. carbon monoxide in methanol and / or water and / or carbon dioxide by adsorption, a heat exchanger, a pipe for sending the purified gas mixture containing at least hydrogen, methane and carbon monoxide to cool in the heat exchanger to a cryogenic temperature, a washing column, a conduit for feeding the cooled gas mixture into the heat exchanger to the washing column, a conduit for delivering a nitrogen-rich liquid at the top of the the washing column, a pipe for withdrawing a gas containing hydrogen and nitrogen from the head of the washing column, the pipe for withdrawing the gas being connected to the heat exchanger for allowing re that the mixture of hydrogen and nitrogen is heated therein characterized in that it comprises means for sending a flow of nitrogen gas to cool in the heat exchanger, means for liquefying a first portion of the flow of nitrogen cooled and to send it to the pipe to send a nitrogen-rich liquid at the top of the washing column, a turbine, a pipe to send a second part of the cooled nitrogen flow to the turbine, a pipe for send all the second part of the expanded nitrogen into the turbine to heat up in the heat exchanger and a pipe to take out the second part of heated nitrogen in the heat exchanger, until the end of the latter, to constitute an auxiliary flow of nitrogen, this line being connected:
i) à l'unité pour épurer le mélange gazeux pour y amener au moins une partie du débit auxiliaire comme gaz de régénération ou  i) to the unit for purifying the gaseous mixture to bring therein at least a portion of the auxiliary flow rate as regeneration gas or
ii) à une colonne de strippage de sorte qu'au moins une partie du débit auxiliaire puisse servir de gaz de strippage, l'appareil comprenant une unité de traitement par absorption qui produit le mélange gazeux contenant de l'hydrogène et du monoxyde de carbone comprenant la colonne de strippage.  ii) a stripping column so that at least a portion of the auxiliary flow can serve as a stripping gas, the apparatus comprising an absorption treatment unit which produces the gaseous mixture containing hydrogen and carbon monoxide comprising the stripping column.
Selon d'autres caractéristiques facultatives :  According to other optional features:
- l'appareil ne comprend pas de moyen de liquéfaction de l'azote détendu dans la turbine.  the apparatus does not comprise means for liquefying the nitrogen expanded in the turbine.
l'appareil ne comprend pas de compresseur de l'azote détendu dans la turbine.  the apparatus does not include a compressor of nitrogen expanded in the turbine.
l'appareil comprend une seule colonne de séparation à basse température pour séparer le mélange gazeux épuré ou un fluide dérivé du mélange gazeux épuré.  the apparatus comprises a single low temperature separation column for separating the purified gas mixture or a fluid derived from the purified gas mixture.
l'appareil comprend une conduite pour envoyer un débit additionnel d'azote à l'unité d'adsorption pour la régénération.  the apparatus comprises a pipe for sending an additional flow of nitrogen to the adsorption unit for regeneration.
Selon un autre aspect de l'invention il est prévu un appareil de production d'un mélange d'hydrogène et d'azote comprenant un appareil de lavage tel que décrit ci-dessus ainsi qu'une unité de traitement par absorption qui produit le mélange gazeux contenant de l'hydrogène et du monoxyde de carbone comprenant une colonne de strippage et des moyens pour envoyer au moins une partie du débit auxiliaire d'azote à la colonne de strippage comme gaz de strippage.  According to another aspect of the invention there is provided an apparatus for producing a mixture of hydrogen and nitrogen comprising a washing apparatus as described above and an absorption treatment unit which produces the mixture. gas containing hydrogen and carbon monoxide comprising a stripping column and means for sending at least a portion of the auxiliary nitrogen flow to the stripping column as a stripping gas.
L'invention sera décrite en plus de détail en se référant à la figure qui illustre un procédé selon l'invention.  The invention will be described in more detail with reference to the figure which illustrates a method according to the invention.
Un gaz de synthèse contenant de l'hydrogène, du méthane et du monoxyde de carbone est traité dans une unité d'absorption 1 , par exemple de type Rectisol ® au méthanol, utilisant au moins une colonne de strippage.  A synthesis gas containing hydrogen, methane and carbon monoxide is treated in an absorption unit 1, for example of the methanol Rectisol® type, using at least one stripping column.
Le gaz produit 3 contenant de l'hydrogène, de l'azote, du méthane et du monoxyde de carbone ainsi que de l'eau et/ou du dioxyde de carbone et/ou du méthanol est épuré en méthanol et/ou en eau et/ou en dioxyde de carbone, si un de ces impuretés est présente, dans une unité d'adsorption 5 pour produire un gaz épuré 7. Le gaz épuré est refroidi dans un échangeur de chaleur 9 jusqu'à une température d'entre -180°C et -190°C pour former un gaz refroidi 1 1 . Le gaz refroidi 1 1 est envoyé en cuve d'une colonne de lavage 13. The product gas 3 containing hydrogen, nitrogen, methane and carbon monoxide and water and / or carbon dioxide and / or methanol is purified to methanol and / or water and and / or carbon dioxide, if one of these impurities is present, in an adsorption unit 5 to produce a purified gas 7. The purified gas is cooled in a heat exchanger 9 to a temperature of between -180 ° C and -190 ° C to form a cooled gas 1 1. The cooled gas 11 is sent to the bottom of a washing column 13.
La colonne de lavage 13 est alimentée en tête par de l'azote liquide 31 produit en refroidissant une partie de l'azote gazeux 25, provenant d'un appareil de séparation d'air, dans un échangeur de chaleur 9A et ensuite dans l'échangeur de chaleur 9. Le liquide de cuve 15 de la colonne 13 enrichi en monoxyde de carbone et appauvri en hydrogène est détendu dans une vanne et envoyé à un séparateur de phase 1 7. Le gaz produit 1 9 se réchauffe et le liquide produit 21 se réchauffe et se vaporise dans l'échangeur de chaleur 9 et sont mélangés pour former un débit 23 qui se réchauffe dans l'échangeur de chaleur 9A pour former un gaz résiduaire.  The washing column 13 is fed at the top with liquid nitrogen 31 produced by cooling a portion of the nitrogen gas 25 from an air separation apparatus into a heat exchanger 9A and then into the heat exchanger 9. The column liquid 15 of the carbon monoxide enriched column 13 and depleted of hydrogen is expanded in a valve and sent to a phase separator 1 7. The product gas 19 is heated and the liquid produced 21 heats up and vaporizes in the heat exchanger 9 and is mixed to form a flow 23 which heats up in the heat exchanger 9A to form a waste gas.
Une partie de l'azote gazeux 25 se refroidit uniquement dans l'échangeur 9 et ensuite est détendue dans une turbine 41 pour former un gaz 44 qui se réchauffe dans les échangeurs 9A et 9 jusqu'au bout chaud de l'échangeur 9A. Ce gaz détendu 44 constitue un gaz auxiliaire et peut servir comme gaz de régénération 47 pour l'unité d'adsorption 5 et/ou comme gaz de strippage pour une colonne de strippage de l'unité d'absorption 1 .  Part of the nitrogen gas cools only in the exchanger 9 and then is expanded in a turbine 41 to form a gas 44 which heats in the exchangers 9A and 9 to the hot end of the exchanger 9A. This expanded gas 44 constitutes an auxiliary gas and can serve as a regeneration gas 47 for the adsorption unit 5 and / or as a stripping gas for a stripping column of the absorption unit 1.
Une autre partie de l'azote 33 se refroidit dans les échangeurs 9A et 9 et est mélangé avec le gaz de tête 35 de la colonne de lavage 13 pour obtenir un rapport H2/N2 voulu dans le gaz 37. Le gaz de tête 35 a été réchauffé de -190°C à -180°C dans l'échangeur 9 (pas illustré) avant d'être mélangé avec le gaz 33. Le gaz formé 37 est divisé en deux en aval de l'échanger 9 et en amont de l'échangeur 9A, un débit 42 étant envoyé à l'unité d'absorption pour s'y réchauffer et un débit 39 se réchauffant dans l'échangeur 9A. Le mélange 43 formé des débits 42, 39 constitue le mélange d'hydrogène et d'azote qui est le produit du procédé. Another part of the nitrogen 33 cools in the exchangers 9A and 9 and is mixed with the overhead gas 35 of the washing column 13 to obtain a desired H 2 / N 2 ratio in the gas 37. The overhead gas 35 was warmed from -190 ° C to -180 ° C in the exchanger 9 (not shown) before being mixed with the gas 33. The formed gas 37 is divided in two downstream of the exchange 9 and in upstream of the exchanger 9A, a flow 42 being sent to the absorption unit for heating and a flow 39 heating in the exchanger 9A. The mixture 43 formed of flow 42, 39 is the mixture of hydrogen and nitrogen which is the product of the process.
Un débit d'azote 49 sera éventuellement requis pour régénérer l'unité d'adsorption 5.  A nitrogen flow rate 49 may be required to regenerate the adsorption unit 5.
Le tableau compare le procédé selon l'invention avec turbine et le procédé sans turbine. Même si de l'azote haute pression supplémentaire provenant de la séparation d'air est requis, la pression de l'azote est plus basse et la consommation d'azote liquide nulle selon l'invention. L'azote supplémentaire utilisé sert pour d'autres utilisations. La pression plus basse et la réduction de consommation d'azote liquide permettre de réduire la consommation d'énergie d'environ 8%. Avec turbine Sans turbine The table compares the process according to the invention with a turbine and the process without a turbine. Even if additional high pressure nitrogen from the air separation is required, the nitrogen pressure is lower and the liquid nitrogen consumption is zero according to the invention. The additional nitrogen used is for other uses. The lower pressure and the reduction in liquid nitrogen consumption can reduce energy consumption by around 8%. With turbine Without turbine
Débit d'azote (Nm3/h) 61453 58608 Nitrogen flow (Nm 3 / h) 61453 58608
Pression d'azote (bar abs) 30.5 38.8 Nitrogen pressure (bar abs) 30.5 38.8
Consonnnnation d'azote liquide (Nm3/h) 0 710 Conservation of liquid nitrogen (Nm 3 / h) 0 710
Consonnnnation d'énergie globale Consonnnation of global energy
8893 9705 (KW)  8893 9705 (KW)

Claims

Revendications claims
1 . Procédé de lavage à température cryogénique pour produire un mélange d'hydrogène et d'azote dans lequel : 1. A cryogenic temperature washing process for producing a mixture of hydrogen and nitrogen in which:
i) Un mélange gazeux (3,1 1 ) contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone ainsi que du méthanol et/ou de l'eau et/ou du dioxyde de carbone est épuré en méthanol et/ou eau et/ou en dioxyde de carbone par adsorption dans une unité d'adsorption.  (i) A gaseous mixture (3.1 l) containing at least hydrogen, methane and carbon monoxide and methanol and / or water and / or carbon dioxide is purified to methanol and / or or water and / or carbon dioxide by adsorption in an adsorption unit.
ii) Le mélange gazeux épuré est refroidi dans un échangeur de chaleur (9A, 9) jusqu'à une température cryogénique et envoyé dans une colonne de lavage (13).  ii) The purified gas mixture is cooled in a heat exchanger (9A, 9) to a cryogenic temperature and sent to a washing column (13).
iii) Un liquide riche en azote (31 ) est envoyé en tête de la colonne de lavage.  iii) A nitrogen-rich liquid (31) is sent to the top of the wash column.
iv) Un gaz contenant de l'hydrogène et de l'azote (35) est soutiré de la tête de la colonne de lavage et réchauffé pour constituer le mélange d'hydrogène et d'azote.  iv) A gas containing hydrogen and nitrogen (35) is withdrawn from the top of the wash column and heated to form the mixture of hydrogen and nitrogen.
v) Un débit d'azote gazeux (25) est refroidi dans l'échangeur de chaleur et divisé en deux parties, une première partie de l'azote est liquéfiée pour constituer le liquide riche en azote et une deuxième partie (27) de l'azote est détendue dans une turbine (41 ), caractérisé en ce que tout l'azote détendu dans la turbine est réchauffé dans l'échangeur de chaleur pour constituer un débit auxiliaire d'azote (44), et  v) A flow of nitrogen gas (25) is cooled in the heat exchanger and divided into two parts, a first portion of the nitrogen is liquefied to form the nitrogen-rich liquid and a second portion (27) of the nitrogen is expanded in a turbine (41), characterized in that all nitrogen expanded in the turbine is heated in the heat exchanger to form an auxiliary nitrogen flow (44), and
vi) au moins une partie du débit auxiliaire d'azote sert à régénérer l'unité d'adsorption, sans avoir été comprimé ou liquéfié après la détente dans la turbine ou  vi) at least a portion of the auxiliary nitrogen flow serves to regenerate the adsorption unit without having been compressed or liquefied after expansion in the turbine or
vii) Le mélange gazeux (3,1 1 ) provient d'une unité d'absorption (1 ) et au moins une partie (45) du débit auxiliaire d'azote (44) sert comme gaz de strippage dans une colonne de strippage de l'unité d'absorption .  (vii) The gaseous mixture (3.1 1) comes from an absorption unit (1) and at least a portion (45) of the auxiliary nitrogen flow (44) serves as a stripper gas in a stripping column of the absorption unit.
2. Procédé selon la revendication 1 dans lequel une troisième partie (33) de l'azote est mélangée avec le gaz de tête (35) de la colonne de lavage pour ajuster le rapport hydrogène/azote. The method of claim 1 wherein a third portion (33) of the nitrogen is mixed with the overhead gas (35) of the wash column to adjust the hydrogen / nitrogen ratio.
3. Procédé selon l'une des revendications précédentes dans lequel l'azote gazeux (25) provient d'un appareil de séparation d'air. 3. Method according to one of the preceding claims wherein the nitrogen gas (25) comes from an air separation apparatus.
4. Procédé selon la revendication 3 dans lequel l'azote gazeux (25) est comprimé dans un compresseur d'azote à une pression d'au plus 35 bars en amont de l'échangeur de chaleur. 4. The method of claim 3 wherein the nitrogen gas (25) is compressed in a nitrogen compressor at a pressure of at most 35 bars upstream of the heat exchanger.
5. Procédé selon la revendication 4 dans lequel aucune partie de l'azote gazeux détendu (44) n'est renvoyée au compresseur d'azote. The process of claim 4 wherein no portion of the expanded nitrogen gas (44) is returned to the nitrogen compressor.
6. Procédé selon une des revendications précédentes dans lequel l'azote gazeux détendu se réchauffe jusqu'au bout chaud de l'échangeur de chaleur (9). 6. Method according to one of the preceding claims wherein the expanded nitrogen gas is heated to the hot end of the heat exchanger (9).
7. Appareil de lavage à température cryogénique pour produire un mélange d'hydrogène et d'azote comprenant une unité pour épurer un mélange gazeux (3) contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone en méthanol et/ou en eau et/ou en dioxyde de carbone par adsorption, un échangeur de chaleur (9, 9A), une conduite pour envoyer le mélange gazeux épuré contenant au moins de l'hydrogène, du méthane et du monoxyde de carbone se refroidir dans l'échangeur de chaleur jusqu'à une température cryogénique, une colonne de lavage (13), une conduite pour envoyer le mélange gazeux refroidi dans l'échangeur de chaleur à la colonne de lavage, une conduite pour envoyer un liquide riche en azote en tête de la colonne de lavage, une conduite pour soutirer un gaz contenant de l'hydrogène et de l'azote de la tête de la colonne de lavage, la conduite pour soutirer le gaz étant reliée à l'échangeur de chaleur pour permettre que le mélange d'hydrogène et d'azote s'y réchauffé caractérisé en ce qu' il comprend des moyens pour envoyer un débit d'azote gazeux se refroidir dans l'échangeur de chaleur, des moyens pour liquéfier une première partie du débit d'azote refroidi et pour l'envoyer à la conduite pour envoyer un liquide riche en azote en tête de la colonne de lavage, une turbine (41 ), une conduite pour envoyer une deuxième partie du débit d'azote refroidi à la turbine, une conduite pour envoyer toute la deuxième partie d'azote détendue dans la turbine (44) se réchauffer dans l'échangeur de chaleur, une conduite pour sortir toute la deuxième partie d'azote réchauffée dans l'échangeur de chaleur jusqu' au bout chaud de celui-ci, pour constituer un débit auxiliaire d'azote, cette conduite étant reliée : A cryogenic temperature washing apparatus for producing a mixture of hydrogen and nitrogen comprising a unit for purifying a gaseous mixture (3) containing at least hydrogen, methane and carbon monoxide to methanol and / or in water and / or carbon dioxide by adsorption, a heat exchanger (9, 9A), a pipe for sending the purified gas mixture containing at least hydrogen, methane and carbon monoxide to cool in the heat exchanger to a cryogenic temperature, a washing column (13), a pipe for feeding the cooled gas mixture into the heat exchanger to the washing column, a pipe for delivering a nitrogen-rich liquid at the top of the the washing column, a line for withdrawing a gas containing hydrogen and nitrogen from the head of the washing column, the pipe for withdrawing the gas being connected to the heat exchanger to allow the mixture of hydrogen and characterized in that it comprises means for sending a flow of nitrogen gas to be cooled in the heat exchanger, means for liquefying a first portion of the cooled nitrogen flow and for the send to the pipe to send a nitrogen-rich liquid at the top of the washing column, a turbine (41), a pipe to send a second part of the cooled nitrogen flow to the turbine, a pipe to send the whole second part Nitrogen expanded in the turbine (44) to heat up in the heat exchanger, a pipe to take out all the second part of nitrogen heated in the heat exchanger up to the hot end thereof, to form an auxiliary flow of nitrogen, this pipe being connected:
i) à l'unité pour épurer le mélange gazeux pour y amener au moins une partie du débit auxiliaire comme gaz de régénération ou  i) to the unit for purifying the gaseous mixture to bring therein at least a portion of the auxiliary flow rate as regeneration gas or
ii) à une colonne de strippage de sorte qu'au moins une partie du débit auxiliaire puisse servir de gaz de strippage, l'appareil comprenant une unité de traitement par absorption (1 ) qui produit le mélange gazeux contenant de l'hydrogène et du monoxyde de carbone comprenant la colonne de strippage l'appareil ne comprenant pas de moyen de liquéfaction de l'azote détendu dans la turbine ou de compresseur de l'azote détendu dans la turbine.  ii) a stripping column so that at least a portion of the auxiliary flow can serve as a stripping gas, the apparatus comprising an absorption treatment unit (1) which produces the gaseous mixture containing hydrogen and carbon monoxide comprising the stripping column the apparatus not comprising means for liquefying the nitrogen expanded in the turbine or compressor nitrogen expanded in the turbine.
PCT/FR2017/051798 2016-07-25 2017-07-03 Method and apparatus for scrubbing at cryogenic temperature in order to produce a mixture of hydrogen and nitrogen WO2018020091A1 (en)

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FR1657107A FR3054304B1 (en) 2016-07-25 2016-07-25 METHOD AND APPARATUS FOR WASHING AT CRYOGENIC TEMPERATURE FOR THE PRODUCTION OF A MIXTURE OF HYDROGEN AND NITROGEN
FR1657107 2016-07-25

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