Classifications

• • 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
  • C01B3/02—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen
  • C01B3/32—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air
  • C01B3/34—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents
  • C01B3/38—Production of hydrogen or of gaseous mixtures containing a substantial proportion of hydrogen by reaction of gaseous or liquid organic compounds with gasifying agents, e.g. water, carbon dioxide, air by reaction of hydrocarbons with gasifying agents using catalysts
  • C01B3/382—Multi-step processes
• • 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
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  • 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
  • C01B2203/0233—Processes for making hydrogen or synthesis gas containing a reforming step containing a catalytic reforming step the reforming step being a steam 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
• • 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
  • C01B2203/0435—Catalytic purification
  • C01B2203/0445—Selective methanation
• • 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
  • C01B2203/06—Integration with other chemical processes
  • C01B2203/068—Ammonia synthesis
• • 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
  • C01B2203/141—At least two reforming, decomposition or partial oxidation steps in parallel
• • 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
• • 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 and preparation of a synthesis gas mixture for the production of ammonia, in which a hydrocarbon-containing starting gas mixture is converted in an autothermal reformer (ATR) by means of steam and oxygen in a Rohsynthesegasgemisch, which optionally supplied after further treatment at least one ammonia synthesis reactor is, wherein supplying only a partial stream of the starting gas mixture to the autothermal reformer, while supplying a further partial stream of the starting gas mixture to a primary reformer and the gas mixture produced there, optionally after further, known per se, treatment steps also supplies a Ammoniaksynthesereaktor.
• ATR autothermal reformer
• Rohsynthesegasgemisch which optionally supplied after further treatment at least one ammonia synthesis reactor is
• a process for the catalytic production of ammonia from a nitrogen-hydrogen mixture in which natural gas passes together with an oxygen-rich gas in an autothermal reformer, where at temperatures in the range of 900 ° C to 1200 ° C, a pressure of 40 to 100 bar and in the presence of a cracking catalyst produces a crude synthesis gas, wherein this crude synthesis gas is withdrawn from the autothermal reformer, cooled, passes through a catalytic conversion to convert CO to H 2 and a converted synthesis gas with an H 2 content of at least 55 vol.% and a CO content of at most 8 vol.%, whereby the converted synthesis gas is subjected to a multistage gas purification to remove CO 2 , CO and CH 4 and an N 2 Generates H 2 mixture, which is fed to an ammonia synthesis for the catalytic production of ammonia.
• WO 2016/198487 AI also a multi-pressure process for the production of ammonia is described in which a starting gas mixture comprising hydrogen, nitrogen, water, methane, optionally argon, carbon monoxide and carbon dioxide is prepared by reforming hydrocarbons, wherein the reforming in an autothermal reformer takes place, which is operated with pure oxygen or with oxygen-enriched air or with air.
• the document EP 0 522 744 A2 discloses a process for the production and preparation of a synthesis gas mixture having the features mentioned in the introduction.
• the conversion of a first partial stream of the starting gas mixture takes place in a primary reformer and a downstream secondary reformer, while a second partial stream of the starting gas mixture is first processed in a Vorreformer and then in an autothermal reformer. Thereafter, both partial streams are combined with each other and it then follows the addition of a nitrogen-containing stream with the gas mixture further nitrogen is supplied.
• this nitrogen-containing stream is a circulating gas, which is recycled from the ammonia synthesis after removal of a product stream and which consequently contains only a smaller proportion of nitrogen and also a larger proportion of hydrogen and carbon monoxide, carbon dioxide and optionally methane. Only after this addition of the recycle gas is an increase in pressure before the synthesis gas is fed to an ammonia synthesis.
• a natural gas is divided into two partial streams, wherein the first partial stream is fed to an autothermal reformer, which is supplied with an oxygen-enriched stream from an air separation plant.
• the second partial flow is fed to a primary steam reformer, which, however, is not followed by a secondary reformer.
• Both partial streams are combined after the primary reformer and then further processed by a CO shift and a pressure swing adsorption and then the treated gas mixture further nitrogen from the air separation plant is supplied.
• This synthesis gas mixture is fed to an ammonia synthesis reactor. A pressure increase of the gas mixture is not described in this document.
• the object of the present invention is to provide a process for the production and preparation of a synthesis gas mixture for the production of ammonia having the features of the aforementioned type, which allows an increase in capacity of an ammonia plant bypassing or significantly weakening the abovementioned bottlenecks ,
• Another concern of the present invention is to efficiently integrate an air separation plant into the revamping operations of an existing ammonia plant.
• the solution of the aforementioned object provides a process for the production and preparation of a synthesis gas mixture for the production of ammonia of the type mentioned above with the features of claim 1.
• the synthesis gas mixture is brought to an elevated pressure which corresponds to the ammonia synthesis pressure and only after the pressure increase the synthesis gas mixture from at least one line further nitrogen before the synthesis gas mixture enters a one- or multi-stage ammonia synthesis.
• the solution according to the invention has the advantage over the known processes that the expensive synthesis gas compressor is thereby relieved.
• the synthesis gas mixture after the pressure increase "additional” nitrogen it is meant that it is preferably a supply of nitrogen in the form of fresh gas from outside the plant and not in shape
• a recycle gas which is recirculated from the reactor, this contains nitrogen, but also other constituents such as, inter alia, hydrogen, wherein the exact composition of the circulating gas would probably have to be determined analytically, so that the addition of circulating gas is unsuitable to set a targeted for the ammonia synthesis stoichiometric ratio of hydrogen to nitrogen of 3: 1 targeted.
• nitrogen from “outside the plant” thus means in this context that this nitrogen originates from outside the actual plant for the production of ammonia and thus not from the recycle gas. If this nitrogen is produced for example in an air separation plant, this air separation plant can of course be installed on the be positioned in the same area as the plant for the production of ammonia This variant is therefore encompassed by the invention.
• further nitrogen is carried out with a purity of at least 60%, preferably with a purity of at least 80 %, more preferably with a purity of at least 90%, particularly preferably with a purity of at least 95% after the pressure increase of the synthesis gas mixture.
• a first partial stream fed to the primary reformer is branched off from a line containing the hydrocarbons and steam and leads the remaining partial stream of this gas mixture to the autothermal reformer.
• the gas mixture leaving the primary reformer is fed to a secondary reformer.
• a primary reformer and a secondary reformer are thus provided in addition to the autothermal reformer.
• the secondary reformer can be operated, for example, with enriched air.
• the use of the secondary reformer has the advantage, in comparison to the method known from US 2011/0297886 AI, that not all the nitrogen required for ammonia production has to be produced in an air separation plant. Rather, in this preferred variant of the present invention, the preferably significantly larger part of the nitrogen is obtained by supplying the process air to the secondary reformer, in which the oxygen contained in the air reacts with additional methane from the starting gas mixture, while the nitrogen contained in the process air subsequently available for ammonia synthesis.
• the crude synthesis gas stream treated in the autothermal reformer and the crude synthesis gas stream treated in the primary reformer are combined, and then a combined treatment of these gas streams takes place before they are fed to an ammonia synthesis reactor.
• the combining is preferably carried out before the CO conversion, more preferably before the cooling section, i. immediately after leaving the ATR and from the secondary reformer.
• the joint preparation of these gas streams comprises at least one step in which a CO conversion and / or a CGyWäsche and / or a methanation take place.
• the treated synthesis gas stream is fed to at least one synthesis gas compressor where it is compressed to an increased pressure Pi, which is higher than the initial pressure, then to a first synthesis unit ("Once "Through” or "GT 'ammonia synthesis, usually comprising a gas preheating, an ammonia converter (this optionally comprising a plurality of catalyst beds with a gas intermediate cooling), a gas cooling, an ammonia condensation and an ammonia deposition), wherein the Gas stream is compressed after the ammonia deposition in the multi-pressure process by means of a further compression stage or another synthesis gas compressor to a pressure p 2 , which is higher than the pressure Pi and this gas stream is then a second synthesis unit ("cyclic ammonia synthesis, also usually comprising a gas preheating, an ammonia converter (this comprising optionally a plurality of catalyst beds with a gas intermediate cooling), a gas cooling,
• the treated synthesis gas stream at least one synthesis gas compressor are fed there compressed to an elevated pressure and then fed to one or more ammonia synthesis reactors.
• the additional nitrogen introduced is produced in an air separation plant and then liquefied and pumped to the pressure Pi or p 2 .
• the nitrogen flowing through the secondary reformer is added, for example, between a second and a third synthesis gas compressor stage of the GT ammonia synthesis, which can be carried out at a pressure Pi in the order of about 100 bar.
• the nitrogen from the air separation plant is preferably pumped directly to the pressure p 2 of the circulatory ammonia synthesis of about 200 bar and is thus guided past the synthesis gas compressor.
• some of the nitrogen from the air separation plant can be added to the OT ammonia synthesis to increase the ammonia yield.
• the fresh gas before the ammonia synthesis thus contains, besides nitrogen and hydrogen, also the argon and methane gases, which are inert in relation to the ammonia synthesis, and possibly helium.
• An existing air separation plant is preferably modernized so far that the products 0 2 and N 2 are almost pure and in liquid form, the argon is preferably separated.
• an autothermal reformer is provided in parallel with the existing primary reformer and optionally secondary reformer, preferably with pure oxygen from the Air separation plant can be operated.
• the liquid oxygen is pumped to the working pressure of the autothermal reformer, for example, about 40 bar and then evaporated, the cold of the liquid oxygen is used.
• the starting gas mixture for example natural gas
• the starting gas mixture for example natural gas
• the natural gas-steam mixture for the autothermal reformer may advantageously be diverted from the main stream directed into the primary reformer only before the primary reformer. In this way, one obtains two piping systems, each with at least one reformer, in which the reforming process takes place in parallel and you can use the previously generated natural gas-steam mixture in both parallel piping systems. It is advantageous to bring both Rohsynthesegasstrom after reforming in the autothermal reformer or in the primary reformer and secondary reformer together again and then process together in further process steps.
• This treatment can comprise, for example, CO conversion and / or CO 2 scrubbing and / or methanation.
• the liquid nitrogen from the air separation plant is preferably pumped to the final synthesis pressure of, for example, about 200 bar and mixed with the fresh gas only after the synthesis gas compressor.
• the cold of the supercritical nitrogen can be used.
• Part of the ammonia can be formed by the OT ammonia synthesis between the compression stages of a syngas compressor (typically between the second and third stages).
• a portion of the nitrogen from the air separation plant after the second compression stage of the synthesis gas compressor is added to the make-up gas to optimize the gas composition prior to OT ammonia synthesis.
• Part of the oxygen is added to the secondary reformer to reduce the residual methane content so that the methane residue after the secondary reformer and after the autothermal reformer is approximately equal. This is advantageous for the economy of the process, since a lower methane residue leads to higher ammonia production.
• the distribution of the gas is new compared to the aforementioned known solutions.
• One advantage is, among other things, the massive relief of all process units between the secondary reformer and the main synthesis, including the process air compressor and the synthesis gas compressor.
• an advantage of the combination according to the invention with the primary reformer is that the heat in the flue gas channel of the primary reformer can be used.
• the preheating of the inlet streams for the autothermal reformer in the flue gas channel of the primary reformer is possible.
• the supplied additional nitrogen from the air separation plant brought by at least one pump to the intended ammonia synthesis pressure and then via a line immediately before the circulatory ammonia synthesis or partially before the OT Ammonia synthesis is supplied.
• a preferred embodiment of the invention provides that both the autothermal reformer and the secondary reformer oxygen is supplied, which was obtained in an air separation plant.
• a preferred embodiment of the invention provides that the secondary reformer process air is supplied, which was preferably previously brought by means of a compressor to an elevated pressure and / or by means of a heat exchanger, preferably in the flue gas duct of the primary reformer, was preheated.
• the process air can be additionally mixed with oxygen from outside, which was obtained in an air separation plant, and this oxygen-enriched air can be supplied to the secondary reformer.
• the present invention furthermore relates to a process for the production of ammonia, in which the preparation of the ammonia is carried out using a synthesis gas mixture produced and prepared in the manner described above.
• a synthesis gas mixture is first generated in this process for the production of ammonia, which contains the gases hydrogen and nitrogen in a ratio H 2 : N 2 greater than 3 and this superstoichiometric synthesis gas mixture is then prior to introduction into the ammonia synthesis reactor added more nitrogen.
• This additional nitrogen was preferably produced in an air separation plant.
• the ammonia synthesis can be carried out either at only one pressure level or alternatively it can be a multi-pressure process.
• the present invention further relates to a plant for the production and processing of a synthesis gas mixture for the production of ammonia, in which a hydrocarbon-containing starting gas mixture is converted in an autothermal reformer by means of steam and oxygen / air in a Rohsynthesegasgemisch, which supplied after further treatment at least one ammonia synthesis reactor is, according to the invention, this plant in addition to at least one autothermal reformer at least one primary reformer and further comprises at least one secondary reformer downstream of the primary reformer in the flow path.
• the autothermal reformer and the secondary reformer are arranged in mutually parallel piping systems, wherein the respective output lines of autothermal reformer and secondary reformer lead in a common conduit system for synthesis gas, preferably before the CO conversion tion.
• this comprises at least one CO conversion and / or at least one CGy wash and / or at least one methanation device, which are arranged in the common synthesis gas line system downstream of autothermal reformer and secondary reformer.
• the present invention further relates to a plant for the production of ammonia comprising a plant for the production and processing of a synthesis gas mixture of the type described above, this plant further comprises according to the invention at least one of the autothermal reformer and the primary reformer and optionally the secondary reformer in the flow downstream ammonia synthesis reactor.
• this plant further comprises according to the invention at least one of the autothermal reformer and the primary reformer and optionally the secondary reformer in the flow downstream ammonia synthesis reactor.
• these may also be two or more ammonia synthesis reactors, which operate at different pressures.
• Figure 1 is a simplified schematic flow diagram of a first exemplary system according to the invention
• Figure 2 is a schematically simplified flow diagram of a second exemplary system according to the invention according to an alternative variant of the present invention.
• FIG. 1 shows a simplified flow diagram of an exemplary plant according to the invention for the production and preparation of a synthesis gas mixture and for the subsequent production of ammonia from this synthesis gas mixture.
• argon is separated and liquid nitrogen from the air separation plant 10 is fed via line 11 to a pump 12 and there brought to a pressure of for example about 200 bar, heated in a heat exchanger 13 and then on the Line 14 fed to the cycle gas before it is fed to a cyclic ammonia synthesis 15.
• the liquid oxygen from the air separation plant 10 is fed via the line 16 to a pump 17, brought there to a higher pressure of for example about 40 bar, then evaporated in an evaporator 18 and a part of the gaseous oxygen is then via the line 19 of the process air the line 24 mixed before the enriched air is supplied to a secondary reformer 20.
• the system supplied process air is compressed in the process air compressor 21, passes via the line 22 in a device 23 for preheating the process air, where it is heated and is then fed via line 24 to a secondary reformer 20.
• the natural gas is supplied via a compressor 25 and the line 26 of the system, then in a heat exchanger 27, preferably in the flue gas duct of the primary reformer, heated to a temperature of, for example, about 380 ° C, desulfurized in a corresponding device 28, then flows through the line 29, where an admixture of steam takes place, then through another heat exchanger 30 in the flue gas duct of the primary reformer, where the gas is heated, for example up to about 480 ° C to 600 ° C and then leaves this heat exchanger 30 via line 31, where then a Dividing the natural gas / steam mixture into two partial streams takes place, of which a partial stream is supplied via the line 32 to the primary reformer 33.
• the reaction of the hydrocarbons with the water vapor takes place to form a synthesis gas mixture which contains carbon monoxide and hydrogen as main components.
• the crude synthesis gas mixture leaving the primary reformer 33 is fed via the line 34 to the above-described secondary reformer 20, in which by the supply of air or oxygen methane to carbon monoxide and Hydrogen according to the reaction equation (1) and (3) and partially the following reaction equation (2) is reacted.
• the synthesis gas mixture leaving the secondary reformer 20 is then cooled, generating steam, and is supplied via the line 35 to a CO conversion 36.
• This cooling is called “waste heat recovery” (WHR), in which the gas gives off the heat to water, which then evaporates, so that the gas is cooled and heat is recovered.
• WHR waste heat recovery
• the so-called CO conversion also referred to as the water gas shift reaction, is used to reduce the carbon monoxide content in the syngas and generate additional hydrogen. It is an exothermic equilibrium reaction which follows the reaction equation (3) given below:
• a C0 2 scrubber 37 is provided to remove the C0 2 from the synthesis gas mixture.
• the synthesis gas flows through a device for methanation in which carbon monoxide or carbon dioxide react at elevated temperatures according to the reaction equations (4) and (5) reproduced below with hydrogen to give methane and water:
• the educt gases hydrogen and nitrogen are present in the generated synthesis gas mixture in a superstoichiometric ratio of more than 3: 1, that is, it contains more hydrogen in the gas mixture relative to nitrogen than is needed for the ammonia synthesis reaction.
• the synthesis gas mixture then enters the synthesis gas compressor, where it can operate, for example, with two compression stages 40 and 41 connected in series and an increase in pressure to, for example, 100 bar takes place in two stages.
• the water content in the fresh gas is too high (water deactivates the catalyst in the ammonia converter), the water is separated after each pressure increase, as exemplified by a device 42 is shown. This can be done both by the condensation and by other methods known in the art.
• the fresh gas enters the OT (once through) - ammonia synthesis 15, consisting of the gas preheating, an ammonia converter (possibly several catalyst beds with a gas intercooling), a gas cooling, an ammonia condensation and ammonia deposition).
• the remaining gas mixture is compressed in the two-pressure process shown in FIG. 1 in a further compressor stage 43 to a higher pressure of, for example, about 200 bar, and then via conduit 44 to a second ammonia synthesis , the circuit ammonia synthesis 45 supplied, also consisting of the gas preheating, ammonia converter (several catalyst beds with a gas intercooling), gas cooling, ammonia condensation and ammonia deposition.
• ammonia synthesis a further ammonia synthesis takes place at a higher pressure level.
• the ammonia is removed as a product via the lines 46 and 47, respectively.
• the supplied via the line 39 synthesis gas mixture indeed contains hydrogen in excess, - the fresh gas before the first ammonia synthesis 15, the OT-ammonia synthesis, via the from the line 14 branching branch 57 further nitrogen can be supplied.
• the remaining nitrogen from the line 14 opens before the second ammonia synthesis, the circulation ammonia synthesis, in the line 44.
• the cyclic ammonia synthesis 45 the ammonia is removed as a product via the line 47.
• the so-called purge gas - is removed via line 53 after synthesis 45 and before the admixing of the fresh gas.
• the gas mixture is fed via line 54 to a further compressor or a further compressor stage 55, in this brought to a required for the reaction of increased pressure and then via the return lines 56, 44 and after the Adding fresh gas and nitrogen from the line 14, the circuit ammonia synthesis 45 supplied so that you can lead unreacted starting materials in the circulation and bring in the ammonia synthesis reactor again to react.
• the crude synthesis gas mixture leaving the autothermal reformer 49 via the line 50 then contains approximately the same proportion of residual methane as the synthesis gas mixture leaving the secondary reformer 20 via the line 35.
• the two gas streams are best after the cooling section before the CO conversion at the branch 51 louen and the combined synthesis gas stream can then be introduced into the CO conversion 36. After the combination, the combined synthesis gas stream from the lines 50 and 35 can thus be further treated together and finally fed to the ammonia syntheses 15 and 45.
• the peculiarity of the method according to the invention thus lies in the fact that the process gas stream, that is, the natural gas / steam mixture is divided into two partial streams, of which a partial stream via the branch line 32 for reforming a primary reformer 33 is fed, while the other partial flow over the second branch line 48 is reformed in the autothermal reformer 49, wherein the two partial streams are then reunited after the respective reforming at the branch 51 and thereafter treated together in the further process.
• a further advantage of the method according to the invention is that the liquid nitrogen from the air separation plant 10 is pumped to the final synthesis pressure of, for example, about 200 bar (with significantly less energy expenditure compared with the compression of the gaseous nitrogen to the same pressure) and then via the line 14 bypassing the synthesis gas compressor 40 is mixed with fresh gas, which flows through the line 44 for cyclic ammonia synthesis 45, so that the synthesis gas compressor is relieved.
• the cold of the supercritical nitrogen is used beforehand.
• FIG. 1 shows a simplified flow diagram according to a second alternative variant of an exemplary plant according to the invention for the production of ammonia.
• the synthesis of the ammonia takes place at only one pressure level. Large areas of the plant scheme agree with the embodiment previously described with reference to FIG.
• the water is separated after each pressure increase, as exemplified by a device 42 is shown. This can be done both by the condensation and by other methods known in the art.
• the fresh gas is compressed to the synthesis pressure of, for example, about 200 bar and then fed via the line 44 of the cyclic ammonia synthesis 45, in which the ammonia synthesis takes place.
• the synthesis gas mixture supplied via the line 52 contains hydrogen in an excess, the gas mixture is supplied via the line 14 prior to the cyclic ammonia synthesis 45 fed additional nitrogen.
• the nitrogen line 14 opens into the line 44, which leads the synthesis gas mixture.
• the ammonia is removed as a product via line 47. So that the methane and argon which are inert for the ammonia synthesis and, if appropriate, helium do not accumulate in the recycle gas, a portion of the gas - the so-called purge gas - is removed via the line 53 after the synthesis 45 and before the admixing of the fresh gas.
• the gas mixture is fed via line 54 to a further compressor or a further compressor stage 55, in this brought to an elevated pressure required for the reaction and then via the return lines 56, 44 and after the admixing of the fresh gas and the nitrogen from the line 14, the circulation ammonia synthesis 45 is supplied so that you can lead unreacted starting materials in the circulation and bring in the ammonia synthesis reactor again to react.
• a branched first partial flow of the natural gas / steam mixture is introduced via the branch line 32 into the primary reformer.
• the second partial stream is fed via the line 48 to an autothermal reformer 49, to which oxygen is supplied via a partial stream diverted from the line 19.
• the crude synthesis gas mixture leaving the autothermal reformer 49 via the line 50 then contains approximately the same proportion of residual methane as the synthesis gas mixture leaving the secondary reformer 20 via the line 35.
• the two gas streams are best combined after the cooling section before the CO conversion at the branch 51 and the combined synthesis gas stream can then be introduced into the CO conversion 36.
• the combined synthesis gas stream from lines 50 and 35 can thus be further treated together and finally fed to the cyclic ammonia synthesis 45.
• the peculiarity of the method according to the invention is thus that the process gas stream, that is, the natural gas / steam mixture is divided into two streams, of which a partial stream via the branch line 32 for reforming a primary reformer 33 and then a secondary reformer is fed during the Other partial flow is reformed via the second branch line 48 in the autothermal reformer 49, wherein the two partial flows are then reunited after the respective reforming at the branch 51 and subsequently treated together in the further process.
• a further advantage of the method according to the invention is that the liquid nitrogen from the air separation plant 10 is pumped to the final synthesis pressure of, for example, about 200 bar (with significantly less energy expenditure compared with the compression of the gaseous nitrogen to the same pressure) and then via the line 14 bypassing the synthesis gas compressor 40 is mixed with fresh gas, which flows via the line 44 for cyclic ammonia synthesis 45.
• the cold of the supercritical nitrogen is used beforehand.

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• 2017
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