Method for producing synthesis gas
Patent Information
- Application Number
- PCT/EP2026/057680
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-28
- Filing Date
- 2026-03-18
- Publication Date
- 2026-10-01
Smart Images
Figure EP2026057680_01102026_PF_FP_ABST
Abstract
Description
[0001] thyssenkrupp Uhde GmbH
[0002] thyssenkrupp AG
[0003] Process for producing synthesis gas
[0004] The present invention relates to a process for ammonia synthesis by autothermal reforming, wherein heat energy is provided by operating a fired heater with a hydrocarbon-containing fuel gas and an oxygen-containing oxidizing agent gas, wherein the oxidizing agent gas contains less than 20 vol% N2.
[0005] State of the art
[0006] In light of global population growth, the development of flexible and efficient fertilizers is of great and increasing importance. A very large proportion of global fertilizer production consists of urea-based fertilizers. These water-soluble fertilizers decompose in the soil into ammonium salts and represent an important base fertilizer. These urea-based fertilizers can be combined with compounds of other elements such as potassium, manganese, phosphorus, sulfur, selenium, and calcium.
[0007] Urea can be produced according to the simplified equations [1] and [2]:
[0008] 2 NH3+ CO2H2N-COONH4[1]
[0009] H2N-COONH4(NH2)2C0 + H2O [2]
[0010] The two starting materials, ammonia and carbon dioxide, can be produced in ammonia synthesis based on the Haber-Bosch process. Ammonia is the second most produced synthetic chemical worldwide (Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, DOI: IO.IOO2 / 14356OO7.OO2_OII, hereinafter referred to as "Ullmann's"). Furthermore, there has recently been increased interest in using ammonia produced with low CO2 emissions (and thus in a climate-friendly manner) as an energy carrier.
[0011] Ammonia is produced primarily from hydrogen and nitrogen in the presence of an iron catalyst. Temperatures are often between 400 °C and 500 °C at pressures exceeding 100 bar. The main factor influencing process costs is the supply of hydrogen from synthesis gas production (Ullmann's, page 139).
[0012] Accordingly, ammonia is preferably produced in principle as described, for example, in Holleman, Wiberg, Textbook of Inorganic Chemistry, 102nd edition, 2007, pages 662-665 (ISBN 978-3-11-017770-1), based on the “Haber-Bosch process” from the elements according to equation [3]:
[0013] 3 H2+ N22 NH3+ 92.28 kJ [3]
[0014] The reactant nitrogen (N2) can be obtained, for example, by low-temperature air separation from ambient air.
[0015] The hydrogen is conventionally obtained via the “steam reforming process” according to equation [4]:
[0016] C n H 2m + n H2O (n+m) H2+ n CO [4]
[0017] In the subsequent “carbon oxide conversion” (carbon monoxide conversion, CO conversion, water gas conversion reaction, water gas shift reaction) a further conversion takes place according to equation [5]:
[0018] CO + H20 CO2+ H2[5]The carbon dioxide (CO2) produced according to equation [5] can be used, for example, as a carbon dioxide source for urea synthesis according to equations [1] and [2].
[0019] According to equation [4], fossil fuels, usually methane from natural gas, serve as a feedstock for hydrogen production. Ammonia produced in this way is therefore associated with high CO2 emissions. In contrast, due to the numerous consequences of climate change, a reduction in CO2 emissions is being pursued worldwide.
[0020] A well-known way to reduce CO2 emissions during ammonia synthesis is the use of an autothermal reformer (ATR). The ATR-based ammonia process utilizes a fired heater to generate some of the thermal energy required for preheating process media and producing steam. For this purpose, exhaust gas (so-called offgas) from pressure swing adsorption and synthesis gas are combusted in the burner of the fired heater. The ATR-based ammonia process thus offers the advantage that, during the processing of the reformed gas mixture for synthesis, a significantly larger proportion of the CO2 produced can be separated by CO2 scrubbing and, if necessary, sequestered (stored separately) or used for other purposes than with reforming using a combination of primary and secondary reformers.However, a disadvantage is that the exhaust gas from the fired heater is also released into the environment. This means that the heat energy supply contributes significantly to the total CO2 emissions from ammonia synthesis.
[0021] In EP 1 816 103 A2, hydrogen (H2) is separated from a gaseous mixture comprising hydrogen and raw carbon dioxide (CO2). Combustible gas components contained in the raw CO2 are subjected to combustion to generate heat, with at least a portion of the generated heat being recovered by indirect heat exchange with at least a portion of the separated H2 or with a gas derived from it. The invention can be integrated into coal-fired power plants.
[0022] CN 116 161 620 A relates to a device for reducing carbon emissions in natural gas hydrogen production, comprising a water electrolysis module, a natural gas reforming module, an exhaust gas treatment module, a water treatment module, and a power supply module, connected in that order. The water treatment module is connected to the natural gas reforming module and the water electrolysis module, and the water electrolysis module is connected to the exhaust gas treatment module. The power supply module is connected to the natural gas reforming module, the water electrolysis module, and the exhaust gas treatment module.
[0023] The present invention therefore aims to provide a method and a plant for ammonia synthesis based on an ammonia synthesis plant with an autothermal reformer, so that CO2 emissions from ammonia synthesis released into the environment can be reduced.
[0024] Inventive solution
[0025] The object of the invention is surprisingly solved by a method for producing synthesis gas according to claim 1. Further advantageous embodiments are found in the dependent claims.
[0026] The invention further comprises a plant for synthesis gas production according to claim 14. Further advantageous embodiments can be found in the respective dependent claims.
[0027] The invention is further directed, according to claim 21, to the use of the inventive method and / or the inventive plant for the production of synthesis gas for ammonia synthesis or for the provision of hydrogen.
[0028] Furthermore, the invention relates to a method for converting a synthesis gas production plant according to claim 22.
[0029] By providing heat energy through the operation of the fired heater with a hydrocarbon-containing fuel gas and an oxygen-containing oxidizer gas, where the oxidizer gas contains less than 20 vol% N2, the process enables the flue gas from the fired heater to consist essentially of CO2 and water vapor. Thus, the CO2 produced during the ammonia synthesis process can be almost completely captured and sequestered, thereby reducing CO2 emissions from the ammonia synthesis.
[0030] In particular, the fired heater can be operated using an oxyfuel process. An oxyfuel process is understood to be a combustion process in which a (solid, liquid, or gaseous) fuel ("fuel") is not burned with air, as in conventional combustion, but with nearly pure oxygen as the oxidizer, so that the proportion of nitrogen and argon is low; "nearly pure oxygen" means that the oxygen-containing oxidizer gas has a nitrogen content of less than 20% by volume, preferably it is an oxygen-containing oxidizer gas with an oxygen content of at least 80% by volume, particularly preferably at least 90% by volume, and especially at least 95% by volume. As a result of the use of this oxygen-containing oxidizer gas, particularly high flame temperatures are achieved. Under ideal conditions, the exhaust gas consists only of carbon dioxide and water.
[0031] The production of synthesis gas can involve air separation, for example, by providing the required oxygen through an air separation unit. The process for producing synthesis gas includes feeding oxygen from the air separation unit, as an oxygen-containing oxidant gas, into the fired heater. For instance, when converting an existing ammonia synthesis plant, an existing air separation unit can be used to provide the oxygen, similar to the one used to supply nitrogen for mixing with the synthesis gas from autothermal reforming. This avoids or at least reduces the need for additional equipment, as an existing air separation unit can be enlarged instead of installing a new or additional unit.
[0032] The production of synthesis gas can alternatively or additionally include water electrolysis. The supply of oxygen as an oxygen-containing oxidant gas can then be derived from the water electrolysis. This can be particularly advantageous if water electrolysis is already in place, such as in a combination with "green" produced hydrogen or hydrogen-containing synthesis gas.
[0033] The use of an oxygen-containing oxidizing agent gas with a nitrogen content of less than 20 vol% (i.e., "nearly pure oxygen" within the meaning of this invention) in the fired heater is not limited in principle to autothermal reforming; it would also be possible in other reforming processes such as steam methane reforming (SMR) or partial oxidation (POX). However, since the amount of oxygen required in the fired heater for steam methane reforming would be significantly greater than for autothermal reforming, a considerably larger air separation unit would be needed to supply these larger quantities of oxygen. Therefore, this use offers significantly greater advantages for autothermal reforming than for steam methane reforming.
[0034] A hydrocarbon-containing fuel gas, particularly natural gas, is supplied to the fired heater. This allows for a reduction in the volume flow rate required for synthesis gas production compared to using a hydrogen-based synthesis gas provided by the process. This is because the amount of hydrogen supplied by the synthesis gas production process can be reduced. The reduced volume flow rate, for example, lowers the energy required to compress the process gas during synthesis gas production. Preferably, the fuel gas supplied to the fired heater corresponds to the supplied hydrocarbon-containing feedstock.
[0035] Furthermore, the process can include desulfurization of the hydrocarbon-containing fuel gas used as a fuel gas before it is fed into the fired heater. This allows catalyst poisons such as hydrogen sulfide and organic sulfur compounds, which can attack pipes upon cooling and may be present in the hydrocarbon-containing fuel gas, to be adsorbed or otherwise removed from the hydrocarbon-containing fuel gas. The production of synthesis gas can also include desulfurization of the hydrocarbon-containing feedstock provided by a feedstock, which is used as a reactant in the production of synthesis gas. Preferably, the desulfurization of the hydrocarbon-containing fuel gas fed to the fired heater is carried out by desulfurizing the hydrocarbon-containing feedstock provided by the feedstock, which is used as a reactant in the production of synthesis gas.For example, it can be arranged that a hydrocarbon-containing raw material supplied as fuel gas to the fired heater is diverted downstream of the desulfurization process, such as a desulfurization reactor, from the hydrocarbon-containing raw material provided by the raw material feed, which is used as a feedstock in the production of synthesis gas. This avoids or at least reduces the need for additional equipment.
[0036] Preferably, the production of synthesis gas comprises reducing the CO and / or CO2 content in a process gas, particularly in a converted process gas downstream of the ATR, wherein the process includes a step in which exhaust gas obtained during the reduction is fed to the fired heater. For example, carbon monoxide (CO) and / or methane (CH4) contained in the exhaust gas can also be reacted in the fired heater. The CO and / or CO2 reduction in the process gas can, for example, be achieved by CO conversion, CO2 scrubbing, and / or pressure swing adsorption.
[0037] Furthermore, the process can include the condensation of water vapor contained in the flue gas of the fired heater. This enables the separation of CO2 and water vapor.
[0038] Preferably, the process includes purifying the condensed water vapor. This is because dissolved gases, particularly dissolved carbon dioxide, are present in the condensed water vapor. These gases can be separated from the water vapor by purification, thus preventing or at least reducing their release into the atmosphere. Purification can be carried out by stripping (gas scrubbing). Stripping is particularly preferably performed by introducing water vapor or natural gas as the stripping gas (scrubbing medium).
[0039] The process may further include feeding the condensed water vapor back into the process to reduce the CO and / or CO2 content of a process gas. This allows dissolved gases, particularly carbon dioxide, in the condensed water vapor to be (re)introduced into the synthesis gas production process and, for example, scrubbed out in a CO2 scrubber and used for storage or utilization. Preferably, the condensed water vapor with dissolved CO2 is fed back into the main synthesis gas production process through the saturator. This avoids the emission of CO2 dissolved in the flue gas condensate.
[0040] Preferably, the process can include sequestering carbon dioxide contained in the flue gas of the fired heater, for example by storing it in a CO2 storage system. This avoids or at least reduces CO2 emissions from the flue gas. In particular, it enables the production of so-called "blue" ammonia in ammonia synthesis. Unlike so-called "green" ammonia, "blue" ammonia is still produced using natural gas or other hydrocarbon-containing fossil raw materials, but the CO2 generated in the process is captured and stored (sequestered) to reduce the CO2 footprint as much as possible.
[0041] Preferably, the process comprises supplying oxidizer gas to the fired heater, resulting in substoichiometric combustion of the fuel gas. This ensures complete conversion of the oxygen contained in the oxidizer gas, similar to stoichiometric combustion. The substoichiometric supply of oxidizer gas offers the advantage of preventing corrosion caused by oxygen in the flue gas stream that remains unreacted in the fired heater. This allows compliance with oxygen limits for a CO2 pipeline.
[0042] Substoichiometric, as used here, means that the ratio of oxidizer gas to fuel gas is adjusted such that even after complete combustion, a proportion of fuel gas remains in the flue gas. Substoichiometric thus refers to the carbon and hydrogen content in the fuel gas. In particular, it can be provided that a maximum of 90% of the oxidizer gas required for complete combustion of the fuel gas is supplied, preferably a maximum of 95%, and most preferably a maximum of 98%.
[0043] The invention further relates to a plant for synthesis gas production, for example for ammonia synthesis, in particular for carrying out a process according to the invention, comprising a fired heater for providing heat for preheating process streams, in particular a hydrocarbon-containing raw material supplied to the synthesis gas production, and water for steam generation, wherein the synthesis gas production comprises an autothermal reformer (ATR) for reforming the hydrocarbon-containing raw material supplied to the synthesis gas production. The fired heater is designed and configured to be operated with a fuel gas and an oxygen-containing oxidizing gas, wherein the oxidizing gas contains less than 20 vol% N₂. By being designed and configured to operate with a fuel gas and an oxygen-containing oxidizing gas, wherein the oxidizing gas contains less than 20 vol% N₂, the fired heater is designed and configured to operate with a fuel gas and an oxygen-containing oxidizing gas.The system, which contains -% N2, is designed and configured to produce flue gas from the fired heater consisting primarily of CO2 and water vapor. This allows for the capture and sequestration of CO2, enabling the production of "blue" ammonia with virtually zero CO2 emissions from the plant.
[0044] Preferably, the system comprises a condensate treatment unit designed and configured to condense water vapor contained in the flue gas of the fired heater. It may be provided that an inlet of the condensate treatment unit is connected to an outlet of the fired heater such that flue gas from the fired heater can be directed into the condensate treatment unit. Furthermore, the system may include a device for purifying the separated condensate.
[0045] The system may also include a desulfurization reactor for desulfurizing a fuel gas supplied to the fired heater. Alternatively or additionally, the system may have a CO2 storage unit.
[0046] Preferably, the plant has a condensate return system designed and configured to return the separated condensate to the synthesis gas production, in particular to a saturator of the synthesis gas production.
[0047] The invention further relates to the use of the inventive process and / or the inventive plant for the production of synthesis gas for ammonia synthesis or for the provision of hydrogen. Thus, the invention enables the provision of synthesis gas for ammonia synthesis with virtually no CO2 emissions. Since the produced synthesis gas is hydrogen-based, the inventive process and / or the inventive plant can also be used to provide hydrogen for processes other than ammonia synthesis.The invention further relates to a method for retrofitting a synthesis gas production plant comprising a fired heater for heat supply for preheating process streams, in particular a hydrocarbon-containing feedstock supplied to the synthesis gas production plant and water for steam generation, and an autothermal reformer (ATR) for reforming the hydrocarbon-containing feedstock supplied to the synthesis gas production plant. The retrofit method includes providing a fuel gas supply and an oxidant supply, so that the fired heater can be operated with a fuel gas and an oxygen-containing oxidant gas, wherein the oxidant gas contains less than 20 vol% N₂. This allows for a further reduction in CO₂ emissions from an existing synthesis gas production plant, for example, a "blue" synthesis gas production plant.
[0048] The details and advantages disclosed for the inventive process for producing synthesis gas are transferable and applicable to the inventive synthesis gas production plant, the use of the inventive process and / or the inventive plant, as well as the inventive conversion process, and vice versa.
[0049] Furthermore, the invention is explained in more detail with reference to the following figures. The figures do not limit the scope of protection of the invention, but serve only as examples.
[0050] They show:
[0051] Figure 1 shows a schematic flow diagram of a state-of-the-art synthesis gas production plant.
[0052] Figure 2 shows a schematic flow diagram of an embodiment of a synthesis gas production plant according to the invention.
[0053] Figure 1 shows a schematic representation of a prior art plant i for the production of synthesis gas using an ATR-based synthesis gas production process. The synthesis gas can then be used for the synthesis of ammonia (NH3) with the feedstocks natural gas, steam, and air. In practice, ammonia production is divided into the process units "front end" and "back end." The "front end" comprises the production of synthesis gas, while the "back end" consists of ammonia synthesis and product processing.
[0054] In the "front end" of the ammonia process considered here, synthesis gas is produced from the feedstocks natural gas, oxygen, nitrogen, and water. For this purpose, natural gas, as a hydrocarbon-containing raw material, is fed into the process via a natural gas feeder 10 and compressed in a compressor 11 to an operating pressure between 30 and 90 bar. Since catalyst poisons such as hydrogen sulfide and organosulfur compounds are present in the natural gas, these are adsorbed in a desulfurization reactor 12. The natural gas is then fed to a saturator 13, where it is enriched with steam. This enrichment is achieved by process condensate 15, which can thus be recycled back into the process. Because trace substances such as CO2, CH4, CO, MeOH, organic acids, and / or byproducts from the reactions are dissolved in the condensate, a portion of the process condensate 15 leaving the saturator sump is separated and discharged via a blowdown system 14.
[0055] A subsequent pre-reformer 16 converts higher hydrocarbons in the natural gas to methane using a nickel-based catalyst, as soot could otherwise form during further reforming; some hydrogen is also produced here. The pre-reformed gas is then preheated to 500 to 700 °C and mixed with steam via hydrogen inlets 17. The steam is added to establish an advantageous steam-to-carbon ratio (S / C ratio) for synthesis gas production, particularly for the reforming of the natural gas and for a water-gas shift reaction in a subsequent CO converter 21. Water is a feedstock for the pre-reformer 16 and also for the subsequent autothermal reactor (ATR) 18 and the CO converter 21. A higher S / C ratio improves the conversion rate in these process units 16, 18, and 21.At the same time, a minimum amount of steam is usually specified for catalysts of plant 1, which must not be undercut.
[0056] The process gas, enriched with steam, is then fed into the ATR 18. Partial oxidation occurs in a combustion zone of the autothermal reformer 18 through the addition of oxygen via an oxygen supply 19. There, a portion of the hydrogen already generated in the pre-reformer 16 is also combusted. In the subsequent step, a nickel-based catalyst in the ATR 18 converts the unreacted methane in the process to carbon monoxide and hydrogen in a steam reforming reaction until a residual methane content of approximately 1.3 mol% remains in the dry process gas.
[0057] The energy from the endothermic steam reforming process is supplied by the exothermic partial oxidation. Additionally, some of the hydrogen is already generated within the ATR 18 reactor through a water-gas shift reaction. The reactor operates at a pressure between 30 and 70 bar. During the partial oxidation and steam reforming, the gas volume in the ATR 18 increases. According to Le Chatelier's principle, reducing the pressure shifts the equilibrium towards the product side, thereby increasing the reaction conversion. After reforming, heat is recovered from the synthesis gas via a heat exchanger 20, cooling the synthesis gas exiting the ATR from typically between 900 °C and 1100 °C to approximately 460 °C to 340 °C.
[0058] The synthesis gas contains carbon monoxide, which is a catalyst poison for the ammonia catalyst of the back end. This carbon monoxide is converted into more easily separated carbon dioxide in a CO converter 21 via a water-gas shift reaction, simultaneously producing additional hydrogen. Since carbon dioxide, due to its oxygen content, is also detrimental to the ammonia catalyst of the back end, it must also be removed. In the process shown in Figure 1, CO2 is captured downstream of the CO converter 21 by a CO2 scrubber 22, implemented here as a methanol scrubber. The captured CO2 is then removed via a carbon dioxide discharge 23 and sequestered. Upstream of the CO2 scrubber 22, water contained in the synthesis gas can be condensed and separated in order to be fed back into the synthesis gas production in the saturator 13 as process condensate 15.
[0059] To reduce the CO and CO2 content to less than 10 ppmv, the synthesis gas is purified by pressure swing adsorption (PSA). Under high pressure, trace substances bind to an adsorbent, and the purified hydrogen is discharged from the container. The adsorbents are regenerated by decompression and subsequent backflushing with purified hydrogen.
[0060] The exhaust gas 25 (English: offgas) of the PSA 24 is fed to a fired heater 26. The heat generated there is used for preheating the process media and also for steam generation.
[0061] The amount of hydrogen in the exhaust gas of the PSA 24 is adjusted according to the fuel gas demand of the fired heater 26. Since the carbon dioxide separated from the CO2 scrubber 22 is sequestered, the only remaining significant emission source of this process is the flue gas 27 from the fired heater 26. The carbon dioxide in the flue gas originates from the carbon compounds in the off-gas 25 of the PSA 24. These carbon compounds consist primarily of carbon monoxide, carbon dioxide, and methane. A small proportion of the CO2 emissions also comes from two pilot flames, which ensure the ignition capability of the fired heater 26.
[0062] After purification in the PSA 24, the hydrogen-rich synthesis gas is mixed with nitrogen from an air separation plant (not shown here) via a nitrogen supply 28 and fed to the "back end" via a synthesis gas discharge 29.
[0063] Steam is generated in this process. This steam is used for the air separation plant, for turbines (not shown), and as process steam. Steam generation is achieved by utilizing waste heat from the front and back ends. Additionally, some of the steam is produced by the fired heater 26.
[0064] The fired heater 26 provides steam for the subsequent heat exchangers 30 to preheat the synthesis gas. Furthermore, a portion of the steam is used in heat exchanger 31 to provide superheated steam, which is discharged via a steam outlet 32. This superheated steam is used to heat feedwater supplied via a feedwater supply 36. The superheated steam can then be used to drive turbines, for example, for power generation. To provide the superheated steam, a heat exchanger 33, which utilizes waste heat from the back end 35, and a heat exchanger 34, which utilizes waste heat from heat exchanger 20, are also provided.
[0065] The "back end" is not shown here and comprises the production of ammonia from synthesis gas and product processing. The synthesis gas provided by the "front end" is compressed, usually in three stages, and then fed into an ammonia reactor (converter), for example, with several converters and intermediate heat exchangers. The ammonia reaction takes place catalytically in a fixed-bed reactor filled with iron oxide.Typically, the "back end" is operated as a synthesis cycle using a synthesis recirculation compressor, in which the gas mixture ("recirculation gas") is fed downstream of the ammonia reactor to an ammonia separator, in which at least part of the ammonia produced in the ammonia reactor is separated, in order to then - after replacing the extracted gas quantity with fresh gas from the "front end" - be fed back to the ammonia reactor again (however, "back ends" that are not operated in recirculation mode, such as "once-through systems", are also possible).
[0066] If unreacted synthesis gas is recycled in the ammonia synthesis of the "back end," a partial stream can be diverted to prevent an accumulation of inert gases. For example, the mass fraction of ammonia downstream of the ammonia reactor is approximately 15%. To separate the ammonia, the temperature of the product gas is lowered after it passes through the ammonia reactor, allowing the ammonia to condense and be discharged from the plant.
[0067] A disadvantage of the plant 1 shown in Figure 1 is that while the CO2 produced in the “front end” can be separated and sequestered by the CO2 scrubber 22, the flue gas 27 from the fired heater 26 is released into the environment. Thus, the released flue gas 27 contributes a significant portion to the total CO2 emissions of plant 1.
[0068] This results in a need to further reduce CO2 emissions from ATR-based ammonia production. The invention therefore proposes a method and an exemplary plant 1, shown in Figure 2, wherein heat energy is supplied to the heat exchangers 30 and 31 by operating the fired heater 26 using an oxyfuel process. The flue gas 27 thus consists essentially of CO2 and water vapor. The water vapor can be separated by condensation, so that the flue gas stream, which then consists almost exclusively of CO2 (for example, more than 90 vol%), can also be subjected to CO2 sequestration. This allows the advantage of not releasing the CO2 generated in the fired heater 26 into the ambient air, or only in reduced quantities, thereby avoiding or at least reducing CO2 emissions.
[0069] For this purpose, the system 1 shown in Figure 2 has an oxygen supply 101 for supplying oxygen to the fired heater 26 (unless otherwise specified, the elements shown in Figure 2 have the meaning and function described for the respective elements in Figure 1). The oxygen can be supplied by an existing air separation unit of the system 1 (this could, for example, be the air separation unit with which oxygen is supplied to the ATR 18 via the oxygen supply 19 and / or the nitrogen required for ammonia synthesis is obtained from the air). In particular, the oxygen supply 101 is designed and configured to supply the oxygen substoichiometrically.This ensures complete consumption of the supplied oxygen, resulting in a virtually oxygen-free flue gas and preventing corrosion caused by oxygen otherwise present in the flue gas. This allows compliance with the respective oxygen limits for CO2 pipelines.
[0070] Furthermore, in Plant 1 of Figure 2, unlike Plant 1 of Figure 1, desulfurized natural gas is used as fuel gas 103 in addition to the off-gas 25 of PSA 24, rather than synthesis gas. Since the use of natural gas as fuel gas reduces the amount of hydrogen required in the off-gas 25 for operating the fired heater 26, the volume flow rate of the ammonia production front end can be reduced. The desulfurized natural gas is extracted from the synthesis gas production downstream of the desulfurization reactor 12 and supplied to the fired heater 26 as fuel gas 103. Thus, the natural gas supply 10 and the desulfurization reactor 12 can be used to supply the fired heater 26 with fuel gas 103.
[0071] Furthermore, the exhaust gas 25 from the PSA 24 supplied to the fired heater 26 can have a lower hydrogen content, since an increase in the amount of hydrogen in the off-gas 25 is no longer necessary for heat generation by the fired heater 26. This means that a larger proportion of the hydrogen obtained during synthesis gas production is available for ammonia synthesis in the "back end," or, in other words, less H2 needs to be produced for the same quantity of NH3. A certain amount of hydrogen can therefore be provided largely independently of the fuel gas demand of the fired heater 26.
[0072] Furthermore, the plant 1 according to the invention, as shown in Figure 2, comprises a condensate treatment unit 102, which is designed and configured to condense and separate water vapor contained in the flue gas 27 of the fired heater 26. It is also provided for purification of the separated condensate, since carbon dioxide is dissolved in the separated condensate. Purification can be carried out, for example, by stripping with a stripping gas such as steam, natural gas, or another gas. The CO2 separated from the condensate in this way can then be fed back into synthesis gas production, here via the saturator 13, pass through the reformer stages again, and finally be scrubbed in the CO2 scrubber 22 and made available for storage or use via the CO2 discharge 23.
[0073] The carbon dioxide contained in the flue gas 27 after passing through the condensate treatment 102 can also be removed for sequestration or further use. Thus, the inventive system 1 can prevent or at least significantly reduce the release of CO2 emissions from the fired heater 26 into the environment.
[0074] The features of the invention disclosed in the foregoing description, in the drawings and in the claims may be essential for the realization of the invention, both individually and in any combination.
[0075] Reference symbol list
[0076] Annex I
[0077] 10 Natural gas supply
[0078] II Compressor
[0079] 12 Desulfurization reactor
[0080] 13 Saturators
[0081] 14 Blowdown 15 Process condensate
[0082] 16 pre-reformers
[0083] 17 Steam supply
[0084] 18 Autothermal Reformer (ATR) 19 Oxygen Supply
[0085] 20 heat exchangers
[0086] 21 CO converters
[0087] 22 CO2 wash
[0088] 23 CO2 removal
[0089] 24 Pressure Swing Absorption (PSA) 25 Exhaust Gas
[0090] 26 Fired heater
[0091] 27 Flue gas
[0092] 28 Nitrogen supply
[0093] 29 Synthesis gas discharge 30 Additional heat exchangers
[0094] 3b 33? 34 Heat exchanger for steam superheating 32 Steam discharge
[0095] 35 Waste heat from the “back end”
[0096] 36 Feedwater supply
[0097] 101 Oxygen Supply
[0098] 102 Condensate treatment
[0099] 103 Fuel gas
Claims
Patent claims 1. A process for producing synthesis gas, in particular for ammonia synthesis, wherein the production comprises the supply of a hydrocarbon-containing raw material, in particular natural gas, and the reforming of the supplied hydrocarbon-containing raw material, wherein the reforming is autothermal, and wherein the process comprises the provision of thermal energy for preheating process streams, in particular the hydrocarbon-containing raw material and water for steam generation, by means of a fired heater (26), characterized in that the thermal energy is provided by the fired heater (26) by operating the fired heater (26) with a hydrocarbon-containing fuel gas and an oxygen-containing oxidizing gas, wherein the oxidizing gas contains less than 20 vol% N2.
2. The method according to claim 1, wherein the production of synthesis gas comprises air separation, characterized in that the method comprises supplying oxygen from the air separation as oxygen-containing oxidizing agent gas into the fired heater (26).
3. A method according to claim 1 or 2, wherein the production of synthesis gas comprises water electrolysis, characterized in that the method comprises supplying oxygen from the water electrolysis as an oxygen-containing oxidizing agent gas to the fired heater (26).
4. A method according to any one of the preceding claims, characterized in that the hydrocarbon-containing fuel gas supplied to the fired heater (26) is natural gas.
5. A method according to any one of the preceding claims, characterized in that the method comprises desulfurization of the hydrocarbon-containing fuel gas before it is supplied to the fired heater (26).
6. Method according to claim 5, characterized in that the desulfurization of the hydrocarbon-containing fuel gas supplied to the fired heater (26) takes place in a desulfurization (12) of the hydrocarbon-containing raw material provided by a raw material supply (10).
7. A method according to one of the preceding claims, wherein the production of synthesis gas comprises reducing a CO and / or CO2 content in a process gas, characterized in that the method comprises a step in which an exhaust gas (25) obtained during the reduction is supplied to the fired heater (26).
8. Method according to one of the preceding claims, characterized in that the method comprises condensing water vapor contained in a flue gas (27) of the fired heater (26).
9. The method according to claim 8, characterized in that the method comprises purifying the condensed water vapor.
10. Method according to claim 9, characterized in that the purification is carried out by stripping, in particular by the application of steam or natural gas.
11. A method according to any one of claims 8 to 10, wherein the production of synthesis gas comprises reducing the CO and / or CO2 content of the synthesis gas, characterized in that the method comprises adding the condensed water vapor for reduction.
12. A method according to any one of the preceding claims, characterized in that the method comprises sequestering carbon dioxide contained in a flue gas of the fired heater (26).
13. Method according to one of the preceding claims, characterized in that the method comprises supplying oxidizing agent gas to the fired heater (26) so that substoichiometric combustion of the fuel gas takes place.
14. Plant (1) for synthesis gas production, for example for ammonia synthesis, in particular for carrying out a process according to one of claims 1 to 13, comprising a fired heater (26) for providing heat for preheating process streams, in particular a hydrocarbon-containing raw material supplied to the synthesis gas production and water for steam generation, wherein the synthesis gas production comprises an autothermal reformer (18, ATR) for reforming the hydrocarbon-containing raw material supplied to the synthesis gas production, characterized in that the fired heater (26) is designed and configured to be operated with a hydrocarbon-containing fuel gas and an oxygen-containing oxidizing agent gas, wherein the oxidizing agent gas contains less than 20 vol% N2.
15. Plant (1) according to claim 14, characterized in that the plant (1) comprises a condensate treatment (102) which is designed and configured to carry out the condensation of water vapor contained in a flue gas (27) of the fired heater (26).
16. Plant (1) according to claim 15, characterized in that an inlet of the condensate treatment (102) is connected to an outlet of the fired heater (26) such that flue gas (27) from the fired heater (26) can be directed into the condensate treatment (102).
17. Plant (i) according to claim 15 or 16, characterized in that the plant (1) comprises a device for purifying the condensed water vapor.
18. Plant (1) according to one of claims 14 to 17, characterized in that the plant (1) comprises a desulfurization reactor (12) for desulfurizing a fuel gas (103) supplied to the fired heater (26).
19. Plant (1) according to one of claims 15 to 17, characterized in that the plant (1) has a condensate return which is designed and configured to return the condensed water vapor to the synthesis gas production, in particular to a saturator (13) of the synthesis gas production.
20. Plant (1) according to one of claims 14 to 19, characterized in that the plant (1) has a CO2 storage unit.
21. Use of the method according to any one of claims 1 to 13 and / or the plant (1) according to any one of claims 14 to 20 for synthesis gas production for ammonia synthesis or for the provision of hydrogen.
22. A method for converting a plant (1) for synthesis gas production comprising a fired heater (26) for providing heat for preheating process streams, in particular a hydrocarbon-containing raw material supplied to synthesis gas production and water for steam generation, and an autothermal reformer (18, ATR) for reforming the hydrocarbon-containing raw material supplied to synthesis gas production, characterized in that the conversion method includes providing a fuel gas supply and an oxidant supply (101), so that the fired heater (26) can be operated with a hydrocarbon-containing fuel gas (103) and an oxygen-containing oxidant gas, wherein the oxidant gas contains less than 20 vol% N2.