WO2018069173A1 - Procédé de préparation d'ammoniac à partir d'un mélange gazeux de procédé contenant de l'azote et de l'hydrogène - Google Patents

Procédé de préparation d'ammoniac à partir d'un mélange gazeux de procédé contenant de l'azote et de l'hydrogène Download PDF

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WO2018069173A1
WO2018069173A1 PCT/EP2017/075456 EP2017075456W WO2018069173A1 WO 2018069173 A1 WO2018069173 A1 WO 2018069173A1 EP 2017075456 W EP2017075456 W EP 2017075456W WO 2018069173 A1 WO2018069173 A1 WO 2018069173A1
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gas mixture
nitrogen
process gas
centrifugal separator
separation
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PCT/EP2017/075456
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German (de)
English (en)
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Joachim Johanning
Evgeni Gorval
Christiane Potthoff
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Thyssenkrupp Industrial Solutions Ag
Thyssenkrupp Ag
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Priority to EP17784609.4A priority Critical patent/EP3526166A1/fr
Publication of WO2018069173A1 publication Critical patent/WO2018069173A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
    • C01C1/00—Ammonia; Compounds thereof
    • C01C1/02—Preparation, purification or separation of ammonia
    • C01C1/04—Preparation of ammonia by synthesis in the gas phase
    • C01C1/0405—Preparation of ammonia by synthesis in the gas phase from N2 and H2 in presence of a catalyst
    • C01C1/0447—Apparatus other than synthesis reactors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/24—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by centrifugal force
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/10—Nitrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/16—Hydrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/10—Single element gases other than halogens
    • B01D2257/102—Nitrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/50—Carbon oxides
    • B01D2257/504—Carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components
    • B01D53/1475—Removing carbon dioxide
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B04—CENTRIFUGAL APPARATUS OR MACHINES FOR CARRYING-OUT PHYSICAL OR CHEMICAL PROCESSES
    • B04C—APPARATUS USING FREE VORTEX FLOW, e.g. CYCLONES
    • B04C1/00—Apparatus in which the main direction of flow follows a flat spiral ; so-called flat cyclones or vortex chambers
    • 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
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • 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
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0205—Processes for making hydrogen or synthesis gas containing a reforming step
    • C01B2203/0227—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step
    • C01B2203/0244—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being an autothermal reforming step, e.g. secondary reforming processes
    • 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
    • C01B2203/02—Processes for making hydrogen or synthesis gas
    • C01B2203/0283—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step
    • C01B2203/0288—Processes for making hydrogen or synthesis gas containing a CO-shift step, i.e. a water gas shift step containing two CO-shift steps
    • 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
    • C01B2203/042—Purification by adsorption on solids
    • C01B2203/043—Regenerative adsorption process in two or more beds, one for adsorption, the other for regeneration
    • 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
    • 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
    • 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
    • C01B2203/0475—Composition of the impurity the impurity being carbon dioxide
    • 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
    • C01B2203/0495—Composition of the impurity the impurity being water
    • 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
    • C01B2203/12—Feeding the process for making hydrogen or synthesis gas
    • C01B2203/1258—Pre-treatment of the feed
    • 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
    • C01B2203/14—Details of the flowsheet
    • C01B2203/142—At least two reforming, decomposition or partial oxidation steps in series
    • 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
    • C01B2203/14—Details of the flowsheet
    • C01B2203/146—At least two purification steps in series
    • 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
    • C01B2203/14—Details of the flowsheet
    • C01B2203/148—Details of the flowsheet involving a recycle stream to the feed of the process for making hydrogen or synthesis gas
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/151—Reduction of greenhouse gas [GHG] emissions, e.g. CO2
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Definitions

  • the present invention relates to a process for the production of ammonia from a nitrogen and hydrogen-containing process gas mixture which contains at least one further gas component having a higher molecular weight than hydrogen, which is separated from the process gas mixture in at least one separation step.
  • the remaining part of the natural gas is converted into a downstream secondary reformer.
  • the heat required for this purpose is provided in-process (autotherm) by partial oxidation of the process gas itself.
  • autotherm autotherm
  • the secondary reformer is much simpler in terms of its design than the primary reformer and its procurement costs are considerably less expensive. It has therefore been lacking in the past approaches to increase the cleavage performance of the secondary reformer at the expense of the primary reformer to eliminate the primary reformer in the extreme case and ideally provide a purely autothermal reforming. However, this requires a correspondingly greater oxygen addition to the secondary reformer or autothermal reformer. This can be realized only by a larger amount of air or a larger Sa uergstoffg content in the supplied oxygen / nitrogen mixture.
  • a greater oxygen content in the supplied oxygen / nitrogen mixture requires air separation. This is also a very expensive unit.
  • the air separation has a significant power requirement, which has no counterpart in the conventional ammonia plant.
  • an ammonia plant with integrated air separation has a slightly higher specific energy consumption than a plant based on conventional two-stage reforming.
  • cryogenic distillation and pressure swing adsorption are also used for air separation.
  • cryogenic distillation is the more economically advantageous process.
  • the object of the present invention is to provide a more effective and less expensive process for the separation of nitrogen and optionally further gas components with a higher molecular weight from a process gas mixture for ammonia synthesis available.
  • the solution to this problem provides a process according to the invention for the production of ammonia from a nitrogen and hydrogen-containing process gas mixture, in which a separation of nitrogen and optionally further gas components with a higher molecular weight from the process gas mixture is provided with the features of claim 1.
  • Hydrogen has a very low molecular weight of only about 2 kg / kmol, while nitrogen has a ca. 28 kg / kmol. In the gas phase, all molecules occupy the same space, ie. Due to the low molecular weight, hydrogen has a correspondingly low density and experiences significant buoyancy in a heavy gas environment.
  • the heavy gas components preferably accumulate in the outer region, since they displace the lighter hydrogen molecules toward the inner radius.
  • the other gas components are invariably undesirable in the ammonia synthesis, since they at least deteriorate the conditions of synthesis, in the case of the oxygen-carrying species even act as catalyst poisons. These components are therefore limited in the synthesis gas production of ammonia plants usually technically / economically acceptable residual levels, optionally removed. Since these components invariably have larger molecular weights than hydrogen (carbon dioxide about 44 kg / kmol, carbon monoxide about 28 kg / kmol, methane about 16 kg / kmol, argon about 44 kg / kmol) they are used in the centrifugal separation method according to the invention also separated with the nitrogen stream.
  • a circular or spiral tube, a cyclone separator or a centrifuge is provided as centrifugal separator, in which the process gas mixture to be separated is exposed to a high acceleration, so that the heavy gas components accumulate in a radially outer region and are separated there can be.
  • Centrifuges are dynamic devices with rotating components, said spiral tube and the cyclone separator, however, are static separation devices without rotational drive and therefore operate at a particularly low cost.
  • the centrifugal separator, the process gas mixture is supplied via an infeed pipe and preferably via an inlet nozzle.
  • the process gas mixture is accelerated in the centrifugal separator to a defined speed and then guided on a circular path or spiral path, the radius of the circular path or spiral path and the gas velocity in the main flow direction are dimensioned so that the required for the separation centrifugal acceleration.
  • the process gas mixture is separated in the centrifugal separator by baffles, partitions and / or channels in different gas components.
  • At least excess nitrogen and carbon dioxide are separated in the centrifugal separator.
  • carbon dioxide which is obtained, which has been enriched in nitrogen and carbon dioxide is then separated off, preferably in a CGy absorber.
  • the gas mixture obtained after the separation of carbon dioxide, which contains nitrogen and hydrogen radicals, can then be returned, for example via a residual gas line to the primary reformer and used there for heating, ie for providing the heat of reaction.
  • An alternative variant of the invention provides that at least excess nitrogen is separated off in the centrifugal separator. Before introducing the gas mixture into the centrifugal separator or after flowing through the centrifugal separator, at least partially carbon dioxide can be separated from the gas mixture in at least one further separating device in this variant.
  • a preferred development of the method according to the invention provides that the gas stream depleted of nitrogen and carbon dioxide after separation in the centrifugal separator flows through at least one further separation device and / or conversion device in which further separation of carbon dioxide or separation of carbon monoxide occurs before this gas flow the ammonia synthesis is supplied.
  • at least one further separation device for example, a CGyAbsorber into consideration, by means of which C0 2 can be separated from the process gas mixture.
  • a methanation stage can be provided, by means of which it is possible in particular to separate off carbon monoxide which is a catalyst poison in the subsequent ammonia synthesis and which is converted to methane in the methanation by reaction with hydrogen.
  • an H 2 recovery takes place from a purge gas stream derived from the ammonia synthesis, wherein preferably a recycling of the recovered hydrogen to the input-side process gas mixture is provided for the production of ammonia.
  • the process gas mixture flows through at least one primary reformer and at least one secondary reformer before the separation step in the centrifugal separator, optionally only an autothermal reformer and / or at least one CO converter and / or at least one water separator.
  • a CO converter For example, high-temperature CO converter and / or low-temperature CO converter or optionally medium temperature CO converter into consideration.
  • the separation device according to the invention for the separation of gases of higher molecular weight such as nitrogen, carbon monoxide and carbon dioxide by centrifugal separation is thus preferably incorporated into a process by means of which natural gas by reforming with steam, a suitable for ammonia synthesis Rohsynthesegas is obtained, which then in the further process in can advantageously be separated by centrifugal separation of excess nitrogen and other components of higher molecular weight.
  • a further advantage of the present invention is that more methane is burned from the process gas during operation of the secondary reformer with excess air. This increases the CGy component compared to the N 2 component.
  • stoichiometric operation of the secondary reformer is obtained for the downstream urea plant always less C0 2 than would be required for the complete conversion of the entire ammonia to urea.
  • the present invention further relates to a plant for the treatment of a process gas mixture for ammonia synthesis comprising at least one ammonia synthesis reactor in which the synthesis of ammonia from a nitrogen and hydrogen-containing process gas, and at least one ammonia synthesis reactor upstream in the flow path separating device for separating at least one gas component from the Process gas, wherein at least one centrifugal separator is provided as a separator for the separation of excess nitrogen and optionally other gas components with higher molecular weight.
  • this system further comprises at least one primary reformer connected upstream of the centrifugal separator in the flow path and at least one secondary reformer connected downstream of the primary reformer and upstream of the centrifugal separator.
  • the natural gas is first split with steam (steam reforming).
  • steam reforming steam reforming
  • the method according to the invention can be dispensed with the primary reformer with external heating entirely and the entire reforming be made by an autothermal reformer.
  • the system according to the invention further comprises, according to a preferred development, at least one high-temperature CO converter upstream of the centrifugal separator in the flow path and at least one low-temperature CO converter upstream of the centrifugal separator in the flow path, optionally alternatively a medium-temperature CO converter.
  • the CO conversion step uses a portion of the unwanted CO in the cleavage gas to produce H 2 product.
  • a separation device can follow, in which water is separated from the process gas stream.
  • the centrifugal separator according to the invention may be provided to separate nitrogen and other components with a higher molecular weight compared to hydrogen.
  • a separate separate separation device for a separation of C0 2 may be provided, for example, a CGyAbsorber.
  • At least one further separating device or conversion device for separating off or converting carbon dioxide or carbon monoxide in the flow path behind the nitrogen separation by centrifugal separation can also be located, for example.
  • These may be, for example, a CGy absorber for the C0 2 separation and a methanation stage for a conversion of CO into methane.
  • the apparatus realization of the concept according to the invention primarily provides for the centrifugal force separation to be carried out in a static separation apparatus.
  • the flow of the process gas is accelerated, for example, from the supplying pipe by means of an inlet nozzle and a corresponding static pressure difference to the required speed and then guided on a circular path.
  • the radius of the circular path is dimensioned such that the centrifugal acceleration required for the separation occurs.
  • the centrifugal separator comprises a static, non-rotating device with at least one circular or approximately spirally guided pipe through which the process gas mixture to be separated is passed.
  • the gas stream is then divided by suitable separating means such as partitions, baffles, channels or the like and subsequent lines.
  • suitable separating means such as partitions, baffles, channels or the like and subsequent lines.
  • the partial stream drawn off at the periphery contains predominantly the heavy gas components.
  • the circulation angle of the gas flow in the apparatus is in principle a design parameter and determines, in cooperation with the gas velocity and the channel width in the radial direction, the selectivity of the arrangement.
  • the circular or spirally guided tube in its output-side end region at least one partition or subdivision through which at least two channels are formed, via the process gas components with different molecular weights separately flow out of the tube.
  • the process gas components with different molecular weights separately flow out of the tube.
  • the subject matter of the present invention is furthermore a separating device comprising a centrifugal separator for separating gases of higher molecular weight than hydrogen from a hydrogen-containing process gas mixture, in particular for use in a plant of the type described above, wherein the centrifugal separator is a static, non-rotating device with at least one approximately spiral comprises guided tube through which the process gas mixture to be separated is passed.
  • the present invention furthermore relates to the use of a plant or a separation device with the features described above in a process for the production of ammonia from a process gas mixture containing nitrogen and hydrogen.
  • Figure 1 is a schematic flow diagram of a first exemplary system according to the invention for the treatment of a process gas mixture for the production of ammonia;
  • FIG. 2 shows a further schematic flow diagram of a second alternative system according to the invention for treating a process gas mixture for the production of ammonia;
  • FIG. 3 is a simplified schematic diagram of an exemplary centrifugal separator, which is used in the method according to the invention.
  • FIG. 1 shows a schematic flow diagram in which the various parts of the system are each represented by blocks.
  • an input line 10 is shown, through which natural gas is fed into a primary reformer 11, 12 steam is added via the branch line, so that in the primary reformer from the hydrocarbons of the natural gas by a reforming reaction with steam, a synthesis gas mixture is generated among others Contains carbon monoxide and hydrogen.
  • the primary reformer 11 leaving the gas mixture is fed to a secondary reformer 13, which is also supplied from the outside via a line 14 and a compressor 15 air, so that takes place in the secondary reformer further oxidation of the synthesis gas mixture to carbon dioxide and water.
  • the gas mixture leaving the secondary reformer 13 flows through a heat exchanger 16 and is then fed to a high-temperature CO converter 17.
  • a portion of the unwanted CO in the cleavage gas to produce H 2 product is used according to the reaction equation: CO + H 2 0 - »C0 2 + H 2
  • the CO conversion reaction is exothermic and, with decreasing temperature, increasingly shifts its equilibrium to the right side of the reaction equation, i. to carbon dioxide and hydrogen.
  • the high-temperature CO conversion usually takes place at temperatures of approx. 300 ° C to 450 ° C instead and allows a reduction in the CO content, for example, up to approx. 2.5%.
  • a specific catalyst is usually used in a fixed bed, so that the exiting gas mixture is largely in chemical equilibrium.
  • the gas mixture leaving the high-temperature converter 17 passes through a further heat exchanger 18 and is then fed to a low-temperature converter 19 in order to further reduce the CO content.
  • This low-temperature converter 19 also operates using a catalyst usually at temperatures in the range of about 180 ° C to about. 250 ° C and usually allows a further reduction of the CO content to about 0.2%.
  • the gas mixture leaving the low-temperature converter 19 passes through a further heat exchanger 20 and then passes into a water separator 21, in which water is separated off.
  • the thus purified process gas mixture is then fed via the line 22 to a separation device 23, in which a separation of high-molecular weight gas is carried out, namely on the one hand from excess amounts of nitrogen and on the other carbon dioxide.
  • the process gas mixture leaving the separating device 23 is then fed to a C0 2 absorber 24, in which a further separation of C0 2 takes place.
  • the process gas mixture After leaving the C0 2 absorber 24, the process gas mixture passes into a methanation stage 25, in which a methanation for the separation of carbon monoxide and optionally C0 2 takes place, since in particular small amounts of carbon monoxide in the subsequent ammonia synthesis act as a catalyst poison.
  • the methanation follows the following reaction equation:
  • the process gas mixture flows through a compressor 26 and then enters the ammonia synthesis reactor 27.
  • the ammonia synthesis gaseous ammonia is generated, which is supplied to a refrigeration system 28.
  • liquid ammonia is generated, which is then discharged via the output line 29 as a product and stored for example in tanks. If additional ammonia is required in the ammonia synthesis, liquid ammonia from the refrigeration system 28 can also be recycled to the ammonia synthesis 27.
  • the separation device 23 are mainly N 2 and C0 2 separated as components of higher molecular weight, depending on the selectivity and lower amounts of hydrogen may be contained in the separated there gas mixture.
  • This separated, nitrogen and Enriched carbon dioxide, gas mixture is then fed via line 30 to a second CCyAbsorber 31, in which C0 2 is separated.
  • This second CGy absorber is in communication with a regeneration device 32, from which via the output line 33 C0 2 can be removed from the system.
  • a gas mixture which contains substantially N 2 and H 2 can be recycled via a residual gas line 35 to the primary reformer 11.
  • This residual gas line 35 can be supplied with gas streams of separated gases.
  • a purge gas stream from the ammonia synthesis reactor 27 is supplied via line 36 to an H 2 recovery device 37.
  • the hydrogen thus obtained is recycled via the line 38 into the line which leads from the methanation stage 25 to the ammonia synthesis reactor 27, wherein the hydrogen is preferably fed before the compressor 26.
  • the recovered hydrogen can be recycled and used again in the ammonia synthesis.
  • the remaining gases separated off in the device 37 during the H 2 recovery can be supplied via the line 39 to the residual gas line 35. Since the residual gas line 35 leads back to the reformer, these gas shares can be recycled at least energetically.
  • the process gas mixture first flows to the water separator 21 via conduit 22 into a first CGyAbsorber 24, in which a separation of C0 2 is carried out before then passing to C0 2 depleted process gas mixture into the inventive separation device 23, the is designed as a centrifugal separator.
  • a separation of C0 2 is carried out before then passing to C0 2 depleted process gas mixture into the inventive separation device 23
  • predominantly excess nitrogen is separated off in the centrifugal separator 23, since a proportion of CO 2 in the CCy absorber 24 has already been separated beforehand.
  • the nitrogen-depleted gas mixture then flows from the separator 23 to a methanation stage 25 in which a conversion of carbon monoxide occurs according to the reaction equation given above.
  • the process gas mixture thus treated then finally passes into the ammonia synthesis reactor 27, where the synthesis of ammonia from nitrogen and hydrogen takes place (usually according to the Haber-Bosch process).
  • hydrogen in the device 37 can be obtained from the purge gas stream flowing out of the ammonia synthesis reactor via the line 36 be recovered, which is then recycled via line 38 in the region upstream of the ammonia synthesis reactor.
  • the residual gas mixture obtained after separation of the hydrogen can also be supplied in this variant via the line 39 of the residual gas line 35, from where the residual gas is recycled to the primary reformer eleventh
  • the carbon dioxide-laden solvent flowing out of the CO 2 absorber 24 passes into a regeneration device 32.
  • This regeneration device 32 has the task of regenerating the solvent used for CO 2 absorption. From the regeneration device 32, the solvent flows back into the C0 2 absorber 24 after regeneration.
  • the separated in the regeneration device 32 C0 2 can be discharged via the output line 33 from the system.
  • the depleted at C0 2 residual gas stream can be passed from the regeneration device 32 directly into the residual gas line 35 and back to the reformer.
  • separated excess nitrogen which may also contain small amounts of hydrogen, CO and argon, can also be supplied via the line 34 of the residual gas line 35 and thus be led back to the reformer 11.
  • the process control according to the variant of FIG. 1 may require an additional C0 2 absorber 31 and thus potentially the somewhat larger investment costs. Due to the division of the process stream and the conditions which are more favorable in the individual absorbers 24, 31, the apparatuses in this variant are, however, distinctly smaller than the individual C0 2 absorber 24 in the variant of FIG. 2.
  • the variant according to FIG. 1 is suitable thus better for very large plant capacities, where the size of the absorber column is a criterion.
  • the second CO 2 absorber 31 shown in the process variant according to FIG. 1 is required to recover the carbon dioxide separated off with the nitrogen stream and thus a comparable or better CO 2 yield to ensure in conventional procedures.
  • ammonia plants with stoichiometric air addition in the secondary reformer provide too little carbon dioxide to convert all the ammonia produced to urea.
  • Systems with more than stoichiometric air addition in the secondary reformer have significantly more carbon dioxide due to the greater degree of partial oxidation of the process gas and usually allow the complete conversion of the entire ammonia produced in the plant to urea (balanced plant).
  • FIG. 3 an exemplary embodiment of a centrifugal separator 23 which can be used in the method according to the invention as a separating device for separating heavy gases will be explained.
  • this comprises a spirally bent tube with a pipe socket 40 at the gas inlet side, through which the process gas mixture, which contains, for example, H 2 , N 2 , C0 2 , CH 4 and Ar, enters the spiral pipe, where it experiences an acceleration.
  • the gas mixture passes through a spiral pipe loop 41 and due to the different molecular weight dependent centrifugal force in the separator 23, the heavier gas components accumulate in the radially outer region of the tube, while the lighter hydrogen accumulates in the radially inner region.
  • the radially outer channel opens into an outer pipe socket 42nd , can be derived through the heavier gases and directed, for example, to the reformer.
  • the radially inner channel opens into an inner pipe socket 43 and contains a depleted in the heavy components such as carbon dioxide, nitrogen and argon gas mixture, ideally a gas mixture in about a mixing ratio H 2 : N 2 of 3: 1, as it was the ammonia synthesis is needed.
  • the effluent with the inner pipe socket 43 gas stream can thus be passed to the ammonia synthesis device, while the outflowing with the outer pipe socket 42 gas stream can be recycled, for example, to the reformer.

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Abstract

La présente invention concerne un procédé de séparation d'azote ainsi que le cas échéant d'autres composants gazeux présentant un poids moléculaire supérieur à partir d'un mélange gazeux de procédé contenant essentiellement de l'azote et de l'hydrogène pour la synthèse d'ammoniac, selon l'invention, la séparation de l'azote ainsi que le cas échéant d'autres composants gazeux présentant un poids moléculaire supérieur étant réalisée à l'aide d'au moins un séparateur centrifuge (23). Alors que les procédés industriels utilisés jusqu'à présent pour la séparation d'azote à partir de l'air pour générer de l'oxygène pur ou à partir d'un gaz de synthèse pour régler un rapport hydrogène-azote approprié pour la synthèse de l'ammoniac sont principalement basés sur le principe de la distillation à basse température, le concept proposé par la présente invention repose sur l'utilisation des poids moléculaires nettement différents des composants du gaz de synthèse dans des installations d'ammoniac pour les séparer dans un champ centrifuge. Étant donné que de cette manière, un excès d'azote peut être éliminé de manière économiquement favorable du mélange gazeux de procédé, on peut faire fonctionner l'appareil de reformage secondaire (13) avec un excès d'air et ainsi optimiser le procédé global.
PCT/EP2017/075456 2016-10-12 2017-10-06 Procédé de préparation d'ammoniac à partir d'un mélange gazeux de procédé contenant de l'azote et de l'hydrogène WO2018069173A1 (fr)

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DE102016219850.5A DE102016219850A1 (de) 2016-10-12 2016-10-12 Verfahren zur Abtrennung von Stickstoff aus einem Prozessgasgemisch
DE102016219850.5 2016-10-12

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CN115445364B (zh) * 2022-09-26 2024-05-03 中国船舶重工集团公司第七一九研究所 一种汽水分离器

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3643452A (en) 1968-08-20 1972-02-22 Petrocarbon Dev Ltd Recovery of gases
DE3100312A1 (de) * 1980-12-29 1983-02-10 Gottfried 6486 Brachttal Bähr Verfahren, vorrichtung und anwendung einer rotations-gasgemischtrennung nach dem prinzip der rotations-sauerstoff-anreicherung, jedoch ohne magnetischen energieinhalt, zum zweck der trennung von im molekulargewicht unterschiedlicher gase, mit aufbereitung der abgase und kreislaufeinsatz fuer die zweite komponente
GB2270309A (en) * 1992-09-04 1994-03-09 Costain Oil Gas & Process Limi Recovery of excess nitrogen from ammonia synthesis feed gas
EP1311335A1 (fr) * 2000-08-24 2003-05-21 Jacques Bellini Procede et dispositif de separation ou d'enrichissement de la concentration dans un melange de composants gazeux ou liquides
US20110064641A1 (en) * 2009-09-16 2011-03-17 Mitsubishi Heavy Industries, Ltd. Ammonia generating method and apparatus therefor
WO2014096631A1 (fr) * 2012-12-18 2014-06-26 DECHERF, Olivier Dispositif et procédé pour séparer un mélange de gaz

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3643452A (en) 1968-08-20 1972-02-22 Petrocarbon Dev Ltd Recovery of gases
DE3100312A1 (de) * 1980-12-29 1983-02-10 Gottfried 6486 Brachttal Bähr Verfahren, vorrichtung und anwendung einer rotations-gasgemischtrennung nach dem prinzip der rotations-sauerstoff-anreicherung, jedoch ohne magnetischen energieinhalt, zum zweck der trennung von im molekulargewicht unterschiedlicher gase, mit aufbereitung der abgase und kreislaufeinsatz fuer die zweite komponente
GB2270309A (en) * 1992-09-04 1994-03-09 Costain Oil Gas & Process Limi Recovery of excess nitrogen from ammonia synthesis feed gas
EP1311335A1 (fr) * 2000-08-24 2003-05-21 Jacques Bellini Procede et dispositif de separation ou d'enrichissement de la concentration dans un melange de composants gazeux ou liquides
US20110064641A1 (en) * 2009-09-16 2011-03-17 Mitsubishi Heavy Industries, Ltd. Ammonia generating method and apparatus therefor
WO2014096631A1 (fr) * 2012-12-18 2014-06-26 DECHERF, Olivier Dispositif et procédé pour séparer un mélange de gaz

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