WO2019008317A1 - Procédé de synthèse de méthanol - Google Patents

Procédé de synthèse de méthanol Download PDF

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Publication number
WO2019008317A1
WO2019008317A1 PCT/GB2018/051602 GB2018051602W WO2019008317A1 WO 2019008317 A1 WO2019008317 A1 WO 2019008317A1 GB 2018051602 W GB2018051602 W GB 2018051602W WO 2019008317 A1 WO2019008317 A1 WO 2019008317A1
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Prior art keywords
methanol
synthesis
gas
stream
loop
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PCT/GB2018/051602
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English (en)
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Simon Robert Early
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Johnson Matthey Public Limited Company
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Publication of WO2019008317A1 publication Critical patent/WO2019008317A1/fr

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    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C31/00Saturated compounds having hydroxy or O-metal groups bound to acyclic carbon atoms
    • C07C31/02Monohydroxylic acyclic alcohols
    • C07C31/04Methanol
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/1516Multisteps
    • CCHEMISTRY; METALLURGY
    • C07ORGANIC CHEMISTRY
    • C07CACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C29/00Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring
    • C07C29/15Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively
    • C07C29/151Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom not belonging to a six-membered aromatic ring by reduction of oxides of carbon exclusively with hydrogen or hydrogen-containing gases
    • C07C29/1516Multisteps
    • C07C29/1518Multisteps one step being the formation of initial mixture of carbon oxides and hydrogen for synthesis
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02PCLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00Technologies relating to chemical industry
    • Y02P20/10Process efficiency
    • Y02P20/129Energy recovery, e.g. by cogeneration, H2recovery or pressure recovery turbines

Definitions

  • This invention relates to a methanol synthesis process and in particular to a method for revamping a methanol synthesis process operating in a synthesis loop.
  • Methanol synthesis is generally performed by passing a synthesis gas comprising hydrogen, carbon oxides and any inert gases at an elevated temperature and pressure through one or more beds of a methanol synthesis catalyst, which is often a copper-containing composition, in a methanol synthesis reactor, to form a product gas stream containing methanol.
  • a crude methanol product is generally recovered by cooling the product gas stream to below the dew point of the methanol and separating off the product as a liquid from a downstream catch-pot.
  • the process is often operated in a loop: thus unreacted gas recovered from the catch-pot is often recycled to the synthesis reactor via a circulator.
  • Fresh synthesis gas termed make-up gas, is added to the recycled unreacted gas to form the synthesis gas.
  • a purge stream is often taken from the circulating gas stream to avoid the build-up of inert gasses.
  • Methanol may be synthesised from the purge gas.
  • US5424335 discloses a process in which the purge gas from a methanol synthesis loop is subjected to a further step of methanol synthesis, preferably while in indirect heat exchange with the purge gas undergoing heating to the synthesis inlet temperature so that the reacted purge gas, containing synthesized methanol, leaves the synthesis catalyst at a temperature below the maximum temperature achieved by the reacting purge gas during passage over the catalyst.
  • the synthesis loop can be operated less efficiently, e.g. at a lower pressure or with added carbon dioxide, than is conventional since the additional methanol produced from the purge gas compensates for the loss of loop efficiency.
  • the addition of the purge gas synthesis stage enables existing plants to be uprated by lowering the loop pressure, thus enabling a greater throughput through the synthesis gas compressor to be achieved.
  • US6258860 discloses a process for the production of methanol from synthesis gas derived from a carbonaceous feedstock which comprises the following steps: (1) part of the unreacted gas stream from a first methanol synthesis zone is recycled to the first methanol zone; (2) another part of the unreacted gas stream from the first methanol synthesis zone is supplied to a second methanol synthesis zone; (3) part of the unreacted gas stream from the second methanol synthesis zone is recycled to the second methanol synthesis zone; (4) hydrogen is recovered from another part of the unreacted gas from the second methanol synthesis zone to give a hydrogen enriched gas stream and a hydrogen depleted gas stream; and (5) recycling the hydrogen depleted gas stream to the second methanol synthesis zone.
  • the invention provides a method for revamping a methanol synthesis process operating in a synthesis loop, comprising the steps of (i) installing a methanol synthesis reactor containing a methanol synthesis catalyst outside of the synthesis loop, (ii) recovering a purge gas stream from the synthesis loop, (iii) passing the at least a portion of the purge gas stream through the installed methanol synthesis reactor to form a product gas stream containing methanol, and (iv) recovering methanol from the product gas stream to form a methanol- depleted gas mixture, wherein a hydrogen stream is recovered from the methanol-depleted gas mixture and fed, along with a carbon dioxide stream, to the synthesis loop.
  • the installed methanol synthesis reactor may be an un-cooled adiabatic reactor.
  • a cooled reactor may be used in which heat exchange with a coolant within the reactor may be used to minimise or control the temperature.
  • a fixed bed of particulate catalyst is cooled by tubes or plates through which a coolant heat exchange medium passes.
  • the catalyst is disposed in tubes around which the coolant heat exchange medium passes.
  • the reactor may also be a quench reactor, or a reactor selected from a tube-cooled converter or a gas- cooled converter, wherein the catalyst bed is cooled in heat exchange with the synthesis gas.
  • the reactor may be cooled by boiling water under pressure, such as an axial flow steam-raising converter, or a radial flow steam-raising converter.
  • the reactors contain fixed beds of methanol synthesis catalyst through which the synthesis gas is passed.
  • the installed methanol synthesis reactor is a gas-cooled converter (GCC) or a tube-cooled converter (TCC), preferably a tube-cooled converter.
  • GCC gas-cooled converter
  • TCC tube-cooled converter
  • the catalyst bed is cooled by feed synthesis gas passing through open ended tubes disposed within the bed that discharge the heated gas to the catalyst.
  • a GCC may be used to cool the catalyst bed by passing the synthesis gas though tubes in a heat exchanger-type arrangement.
  • a GCC is described for example in the aforesaid US 5827901 .
  • TCC is preferred over the GCC in that it is simpler and cheaper to fabricate due to the use of open topped tubes and the elimination of the upper header and all of the differential expansion problems that the gas cooled converter raises.
  • a TCC therefore has the advantage of low equipment cost and lower outlet temperature, which favours the synthesis reaction equilibrium.
  • the installed methanol synthesis reactor is an axial- flow steam-raising converter (aSRC).
  • the synthesis gas typically passes axially through vertical, catalyst-containing tubes that are cooled in heat exchange with boiling water under pressure.
  • the catalyst may be provided in pelleted form directly in the tubes or may be provided in one or more cylindrical containers that direct the flow of synthesis gas both radially and axially to enhance heat transfer.
  • Such contained catalysts and their use in methanol synthesis are described in WO2012146904 (A1).
  • Steam raising converters in which the catalyst is present in tubes cooled by boiling water under pressure offer a useful means to remove heat from the catalyst.
  • Both TCC and aSRC reactors provide a similar proportion of uprate to an existing process, so the decision of which type to use may be based upon whether additional steam is beneficial to the plant or not.
  • the aSRC is easier to start-up and easier to control when considering the various operating cases such as beginning of life (BOL), end of life (EOL), loss of C02 and partial load.
  • the TCC will also handle all of these cases, but desirably includes a start-up heater which may need to be used under low load operation.
  • the steam generated from the aSRC can be used beneficially by integration into the existing plant system, then this may be the preferred option. If the recovered heat has little or no value, the TCC may be the better option as the heat will simply be rejected to air or cooling water.
  • the methanol synthesis catalyst in the installed methanol synthesis reactor is preferably a copper-containing methanol synthesis catalyst, in particular a particulate copper/zinc oxide/alumina catalyst.
  • Particularly suitable catalysts are Mg-doped copper/zinc oxide/alumina catalysts as described in US4788175.
  • Methanol synthesis in the installed methanol synthesis reactor operating outside of the synthesis loop may be effected at pressures in the range 10 to 120 bar abs, and temperatures in the range 130°C to 350°C.
  • the pressure of the synthesis gas at the reactor inlet is preferably 50-100 bar abs, more preferably 70-90 bar abs.
  • the temperature of the synthesis gas at the synthesis reactor inlet is preferably such that the temperature inlet the bed of methanol synthesis catalyst is 200-250°C and at the outlet preferably 230-285°C.
  • Methanol is synthesised from the portion of the purge gas in the installed methanol synthesis reactor thereby forming product gas stream containing methanol. Methanol is recovered from the product gas stream to form a methanol-depleted gas mixture.
  • hydrogen is recovered from the methanol-depleted gas mixture to generate a hydrogen stream and a hydrogen-depleted gas stream.
  • the installed methanol synthesis reactor may be operated on a once-though basis in which case the product gas stream is cooled to below the dew point to condense methanol therefrom, a liquid methanol product stream is recovered using a gas-liquid separator, the resulting methanol-depleted gas stream, treated to recover hydrogen therefrom and the remaining hydrogen-depleted gas stream used as fuel.
  • the installed methanol synthesis reactor may be operated in a loop, outside the main synthesis loop, in which case the product gas stream from the installed methanol synthesis reactor is cooled to below the dew point to condense methanol, a liquid methanol product stream is recovered using a gas-liquid separator, the methanol-depleted gas recovered from the separator is divided into a recycle stream that is compressed and returned to the installed methanol synthesis reactor and a purge stream, which is treated to recover hydrogen therefrom.
  • the recovered hydrogen stream and a carbon dioxide stream are fed to the main synthesis loop.
  • a once-through scheme is preferred for the installed methanol synthesis reactor because it is simpler to install due to the smaller number of equipment items and the limited number of tie-ins required.
  • One of the key benefits of the once-through scheme versus a loop arrangement is that an additional circulator is not required.
  • the installed methanol synthesis reactor will be smaller and therefore cheaper than a reactor used in a loop arrangement.
  • a hydrogen stream is recovered from the methanol-depleted gas mixture and fed, along with a carbon dioxide stream, to the synthesis loop. This offers improved process efficiency compared with US6258860 in which streams are recycled to the purge methanol synthesis reactor.
  • R ([H2]-[C02])/([CO]+[C0 2 ]).
  • R ([H2]-[C02])/([CO]+[C0 2 ]
  • the percentage conversion of carbon oxides to methanol is still lower than for the original synthesis loop, it is higher than for the synthesis loop with only carbon dioxide added. If sufficient hydrogen is available, the economic maximum carbon dioxide that can be added to the synthesis loop is more than double the economic maximum carbon dioxide that can be added without additional hydrogen.
  • a synthesis loop has been provided with both additional carbon dioxide and additional hydrogen that will produce a purge gas with more reactants, both carbon oxides and hydrogen, than the synthesis loop without additional carbon dioxide and additional hydrogen.
  • This purge gas can be economically converted to make additional methanol by installing a new methanol synthesis reactor fed by the said purge gas. Hydrogen recovered from the methanol-depleted gas mixture is sufficient that the overall conversion of carbon oxides for the synthesis loop and the installed methanol reactor is greater than the conversion of the original synthesis loop without additional carbon dioxide and additional hydrogen.
  • the hydrogen may be recovered from the methanol depleted gas mixture by any means suitable, such as by using a Pressure-Swing Adsorption (PSA) unit, a membrane unit, a liquefaction unit, or a combination of two or more of these. However, in a preferred arrangement, the hydrogen is recovered by PSA. PSA units suitable for recovering hydrogen from gas streams are available commercially.
  • the hydrogen stream is preferably >90% vol H2, more preferably >95% vol H2.
  • the recovered hydrogen stream is recycled to the existing synthesis gas loop compression suction and the tails are sent to the fuel system. This allows a low-pressure type PSA unit to be used, which reduces cost and increases reliability significantly.
  • the carbon dioxide stream may be any carbon dioxide stream, for example a carbon dioxide stream recovered from one or more C02-containing process gases.
  • the CO2 recovery may be by a wet CO2 recovery method using liquid chemical or physical absorbents, or dry CO2 recovery using a membrane separation unit or a PSA unit.
  • the CO2 may, for example, be suitably recovered from a flue gas, such as a flue gas from a fired-heater and or a fired primary steam reformer.
  • the carbon dioxide stream may alternatively be recovered from downstream processing of off-gases recovered from the methanol recovery process.
  • the carbon dioxide stream is preferably >70% vol CO2, more preferably >90% vol CO2, most preferably >95% vol
  • the carbon dioxide stream may be injected to the existing syngas loop compressor. Injecting the hydrogen and carbon dioxide streams into the existing synthesis loop may require installing a new compressor for the synthesis loop.
  • the method may be applied to an existing methanol process, in which case the method may form part of a re-vamp of the methanol process, for example to improve methanol recovery. The method may also form part of a new methanol plant and process.
  • the invention further provides a process a process for synthesising methanol comprising the steps of: (i) passing a feed gas mixture comprising a make-up gas and at least a portion of a recycle gas stream to one or more methanol synthesis reactors containing a methanol synthesis catalyst operating in a synthesis loop and recovering a first product gas stream containing methanol from said one or more reactors, (ii) cooling the first product gas stream using one or more heat exchangers and recovering methanol from the first product gas stream thereby forming a first methanol-depleted gas mixture, (iii) dividing the first methanol- depleted gas mixture into a purge gas stream and a loop gas stream, (iv) combining the loop gas stream with the make-up gas to form the feed gas mixture for the synthesis loop, (v) passing at least a portion of the purge gas stream to a methanol synthesis reactor containing a methanol synthesis catalyst installed outside of the synthesis loop to form a
  • the make-up gas is a synthesis gas.
  • Synthesis gases typically comprises hydrogen and carbon dioxide. Carbon monoxide may also be present.
  • the make-up gas is not a gas stream recovered from a synthesis loop. Rather, the make-up gas may be generated by the steam reforming of methane, natural gas or naphtha using established steam reforming processes or partial oxidation processes, or by a combination of reforming processes, such as pre-reforming and/or or steam reforming and/or autothermal reforming. Alternatively, the make-up gas may be generated by the gasification of a carbonaceous feedstock such as coal or biomass.
  • the desired stoichiometry ratio of the make-up gas, R is preferably in the range 1 .9 to 3.0.
  • the optimum addition of carbon dioxide can be calculated from the stoichiometric ratio, R.
  • the mixture of the make-up synthesis gas plus the carbon dioxide stream desirably has a value of R between 1 .95 and 2.00 for the optimum carbon dioxide flow.
  • R the R value will be close to 2.00. If carbon dioxide is not recovered from the crude methanol, then losses due to the solubility of carbon dioxide in the crude methanol mean that the R value will be closer to 1 .95.
  • the resultant feed gas mixture to the methanol synthesis reactor or reactors in the synthesis loop preferably has an R value in the range 2.2 to 2.4.
  • an R value of about 2.3 is optimum.
  • the exact R value may be more than 2.3 if the hydrogen recovery is high enough, or may be less than 2.3 if the hydrogen recovery is lower. If the R value is less than the optimum then the percentage conversion of carbon oxides to methanol in the synthesis loop will be less, requiring the installed methanol reactor to be made larger. If the R value is more than the optimum value, then the percentage conversion of carbon oxides to methanol in the synthesis loop will be slightly higher, allowing the installed methanol reactor to be made smaller.
  • rSRC radial-flow steam raising converter
  • the optimum R value was calculated to be 2.304 for the mixture of make-up synthesis gas, hydrogen and carbon dioxide fed to the synthesis loop.
  • the optimum R value may be slightly different, but will still be in the range of 2.2 to 2.4 for the optimum overall conversion of carbon oxides to methanol.
  • the make-up gas, hydrogen and carbon dioxide feed gas mixture fed to the synthesis loop may be compressed using conventional compression equipment, combined with the recycle gas and passed to the one or more methanol synthesis reactors containing a methanol synthesis catalyst.
  • Methanol is synthesised in the one or more reactors.
  • the reactions may be depicted as follows;
  • the first methanol-depleted gas mixture is used as a recycle gas fed to the one or more methanol synthesis reactors in the loop.
  • the recycle gas may be fed to one or more of them.
  • the first methanol-depleted gas is preferably compressed in a compressor to the loop pressure.
  • the compressor may be the existing circulator or a new larger compressor.
  • the one or more methanol synthesis reactors in the synthesis loop may be an un-cooled adiabatic reactor.
  • one or more cooled reactors may be used in which heat exchange with a coolant within the reactor may be used to minimise or control the temperature.
  • a fixed bed of particulate catalyst is cooled by tubes or plates through which a coolant heat exchange medium passes.
  • the catalyst is disposed in tubes around which the coolant heat exchange medium passes.
  • the reactor may be a quench reactor, or a reactor selected from a tube-cooled converter or a gas-cooled converter, wherein the catalyst bed is cooled in heat exchange with the synthesis gas.
  • the reactor may be cooled by boiling water under pressure, such as an axial flow steam-raising converter, or a radial flow steam- raising converter.
  • the reactors contain fixed beds of methanol synthesis catalyst through which the synthesis gas is passed.
  • One or more methanol synthesis reactors may be used in the synthesis loop of the process.
  • the synthesis loop may be operated with a single cooled methanol synthesis reactor such as a tube-cooled converter or a gas-cooled converter. Where two or more reactors are used, they may be the same or different.
  • the synthesis loop is arranged with a first water-cooled reactor such as an axial flow steam-raising converter or a radial flow steam-raising converter, followed by a gas-cooled or tube-cooled converter, or vice versa.
  • the synthesis loop may be operated with an axial flow steam raising converter followed by a radial flow steam raising converter, or vice-versa.
  • the methanol synthesis catalyst used in the one or more reactors in the synthesis loop again is preferably a copper-containing methanol synthesis catalyst, in particular the methanol synthesis catalyst in the one or more reactors in the synthesis loop is a particulate copper/zinc oxide/alumina catalyst.
  • Particularly suitable catalysts are Mg-doped copper/zinc oxide/alumina catalysts as described in the aforesaid US4788175.
  • the same or different catalysts may be used in different methanol synthesis reactors in the process to enhance the methanol synthesis under different operating conditions and feed gas compositions over the lifetime of the catalysts.
  • Methanol synthesis in the one or more methanol synthesis reactors in the synthesis loop may be effected at pressures in the range 10 to 120 bar abs, and temperatures in the range 130°C to 350°C.
  • the pressure of the synthesis gas at the reactor inlet is preferably 50-100 bar abs, more preferably 70-90 bar abs.
  • the temperature of the synthesis gas at the synthesis reactor inlet is such that the temperature inlet the bed of methanol synthesis catalyst is preferably 200- 250°C and at the outlet preferably 230-285°C.
  • the first and second product gas streams comprise unreacted hydrogen and carbon dioxide, along with methanol vapour.
  • the second product gas stream typically will contain higher amounts of nitrogen and methane than the first product gas stream.
  • the first and second product gas streams are preferably separately cooled in one or more heat exchangers before passing the cooled product gas mixtures containing methanol to gas-liquid separators.
  • the one or more heat exchangers may be water-cooled heat exchangers but preferably include a gas-gas-interchanger in which the product gas mixture containing methanol is cooled in heat exchange with the gas mixture fed to the methanol synthesis reactor. Such a gas-gas interchanger may be used alone or in combination with one or more downstream water-cooled heat exchangers.
  • the purge gas stream is recovered from the first methanol-depleted gas mixture to prevent the build-up of inert gases such as nitrogen and methane in the synthesis loop.
  • the purge stream is desirably recovered from the first methanol-depleted gas mixture upstream of the circulator before it is recycled to the one or more methanol synthesis reactors.
  • a portion of the first methanol-depleted gas mixture is passed to said one or more methanol synthesis reactors in the synthesis loop as the recycle gas stream.
  • the process is operated in a loop with unreacted recycle gas depleted in methanol being mixed with fresh synthesis gas, termed make-up gas, the hydrogen stream and the carbon dioxide stream and the resulting mixture fed to the one or more methanol synthesis reactors.
  • the recycle ratio of methanol-depleted recycle gas to make-up gas may be in the range 0.01 :1 to 25:1 .
  • recycle ratio we mean the molar flow ratio of the recycled gas to the make-up gas that forms the synthesis gas mixture fed to the one or more reactors.
  • the second methanol depleted gas mixture recovered after separation of methanol from the second product gas stream is treated as described above to recover hydrogen.
  • the recovered hydrogen stream is fed with the carbon dioxide stream to the synthesis loop.
  • the resulting hydrogen-depleted gas remaining after hydrogen recovery may be used as a fuel gas, e.g. in upstream steam generation or in a fired primary reformer.
  • the methanol product recovered from the first and second product gas streams contains water and often small amounts of other alcohols and so may be termed "crude methanol".
  • the crude methanol streams recovered from the first and second product gas streams may be combined or treated separately. Preferably they are combined to save on equipment costs.
  • the crude methanol may be further processed, for example by one or more, preferably two or three, stages of distillation to produce a purified methanol product. Alternatively, the crude methanol may be recovered and stored.
  • the methanol product may be subjected to further processing, for example to produce dimethyl ether or formaldehyde, or may be stored for use in electrical power generation, for example using a direct methanol fuel cell to generate electrical power.
  • the methanol may be used as a fuel.
  • Figure 1 depicts a process according to one embodiment of the invention in which an installed methanol synthesis reactor operates on a once-through basis
  • Figure 2 depicts a process according to another embodiment of the invention in which an installed methanol synthesis reactor operates in a loop.
  • FIG. 1 a make-up synthesis gas stream 10 comprising hydrogen, carbon dioxide and carbon monoxide is combined with a carbon dioxide stream 12 and the resulting mixture fed to the first stage of a compressor 14, where it is compressed and combined with a hydrogen stream 16 fed to the second stage of the compressor.
  • a compressed feed gas mixture comprising the make-up gas, carbon dioxide stream and hydrogen stream is fed from the compressor by line 18 to a methanol synthesis unit 20.
  • the methanol synthesis unit 20 may be a pre-existing methanol synthesis unit.
  • the methanol synthesis unit 20 comprises one or more methanol synthesis reactors containing a methanol synthesis catalyst (not shown).
  • the one or more methanol synthesis reactors in the methanol synthesis unit 20 operate in a loop.
  • the compressed feed gas mixture 18 is fed to the one or more methanol synthesis reactors within the unit where methanol is synthesised.
  • a first product gas stream is recovered from the one or more methanol synthesis reactors and cooled to below the dew point in one or more stages of heat exchange (not shown).
  • a crude methanol product stream 22 is separated from a first methanol-depleted gas mixture.
  • the first methanol-depleted gas mixture is divided.
  • a portion is recycled to the feed gas mixture for the one or more methanol synthesis reactors in the unit 20 (not shown).
  • the remaining portion is recovered as a purge gas stream 24.
  • the purge gas stream 24 is heated in gas-gas interchanger 26 and the heated gas fed to the inlet of an installed methanol synthesis reactor 28, operating outside the synthesis loop of unit 20.
  • the installed reactor is a tube-cooled converter.
  • the heated gas is passed upwards through a plurality of tubes 30 disposed within a fixed bed of catalyst 32, where it is further heated.
  • the heated gas discharges into a space above the catalyst bed 32 and then passes downwards through the bed where methanol synthesis takes place.
  • a second product gas stream 34 is recovered from the tube-cooled converter 28 and passed through the gas-gas interchanger 26 where it is cooled in exchange with the purge gas stream 24.
  • the partially-cooled product gas is further cooled in one or more heat exchangers 36 where it is cooled to below the dew point to condense methanol.
  • the cooled product stream is fed from the one or more heat exchangers 36 via line 38 to a gas-liquid separator 40.
  • a crude methanol product stream 42 is recovered from the separator and combined with the crude methanol product stream 22 recovered from the methanol synthesis unit 20.
  • the combined crude methanol streams may be processed, e.g. by one or more stages of distillation (not shown) to produce a purified methanol product.
  • a second methanol-depleted gas mixture 46 is recovered from the gas-liquid separator 40 and fed to a hydrogen recovery unit 48.
  • the hydrogen recovery unit comprises a pressure-swing adsorption unit.
  • a hydrogen stream is recovered from hydrogen recovery unit 48 and passed via line 16 to the compressor 14.
  • a hydrogen-depleted gas mixture 50, rich in nitrogen and methane, is removed from the hydrogen recovery unit 48.
  • Figure 2 The process of Figure 2 is the same as that in Figure 1 except that it additionally comprises a recycle off-take line 60 that takes a portion of the second methanol-depleted gas steam 46 recovered from the separator 40, passes it through a compressor circulator 62 and feeds the compressed gas via a line 64 to be combined with the purge gas stream 24 fed to the installed methanol synthesis reactor 28.
  • the remaining portion of the second methanol-depleted gas mixture 46 is fed via line 66 to the hydrogen recovery unit 48 and is the source of the hydrogen stream 16 fed to the methanol synthesis unit 20.

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  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

L'invention porte sur la modernisation d'un procédé de synthèse de méthanol fonctionnant dans une boucle de synthèse, ledit procédé consistant à : (i) installer un réacteur de synthèse de méthanol contenant un catalyseur de synthèse de méthanol à l'extérieur de la boucle de synthèse, (ii) récupérer un flux de gaz de purge à partir de la boucle de synthèse, (iii) faire passer la ou les parties du flux de gaz de purge à travers le réacteur de synthèse de méthanol installé pour former un flux de gaz produit contenant du méthanol, et (iv) récupérer le méthanol à partir du flux de gaz produit pour former un mélange gazeux appauvri en méthanol, un flux d'hydrogène étant récupéré à partir du mélange gazeux appauvri en méthanol et acheminé, conjointement avec un flux de dioxyde de carbone, vers la boucle de synthèse.
PCT/GB2018/051602 2017-07-07 2018-06-13 Procédé de synthèse de méthanol WO2019008317A1 (fr)

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GBGB1710951.3A GB201710951D0 (en) 2017-07-07 2017-07-07 Methanol synthesis process

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2020035231A1 (fr) * 2018-08-17 2020-02-20 Haldor Topsøe A/S Procédé de production de méthanol dans un réacteur présentant une dérivation
CN112537999A (zh) * 2020-12-22 2021-03-23 华东理工大学 一种甲醇生产装置
US11851393B2 (en) 2019-06-12 2023-12-26 Johnson Matthey Davy Technologies Limited Process for synthesising methanol

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111821820B (zh) * 2020-07-14 2022-07-12 中石化宁波工程有限公司 一种甲醇装置预塔尾气利用系统及方法

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Publication number Priority date Publication date Assignee Title
US6258860B1 (en) * 1995-01-13 2001-07-10 Geoffrey Gerald Weedon Process for the production of methanol
EP3034161A1 (fr) * 2014-12-18 2016-06-22 Haldor Topsøe A/S Procédé et conception de réacteur pour la production de méthanol
WO2017121981A1 (fr) * 2016-01-15 2017-07-20 Johnson Matthey Davy Technologies Limited Procédé de synthèse de méthanol
WO2017121980A1 (fr) * 2016-01-15 2017-07-20 Johnson Matthey Davy Technologies Limited Procédé méthanol

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