Green ammonia synthesis plant in combination with a grey ammonia synthesis plant

Abstract

The invention relates to a green ammonia synthesis plant (1), characterized in that the green ammonia synthesis plant (1) is combined with a grey ammonia synthesis plant (100) in such a way that a mutual material exchange and / or heat exchange of the two plants with one another can take place and / or parts of an infrastructure can be used jointly by both plants. The invention further relates to a method for retrofitting a grey ammonia synthesis plant (100), comprising setting up a green ammonia synthesis plant (1), and to a plant network having a green plant (1) according to the invention and a grey plant (100).

Description

[0001] 240145P10W0 27.08.2025

[0002] Green ammonia synthesis plant in combination with a grey ammonia synthesis plant

[0003] The present invention relates to a green ammonia synthesis plant with a renewable energy-based power supply for the provision of hydrogen, wherein the green plant is combined with a grey ammonia synthesis plant without a renewable energy-based power supply for the provision of hydrogen.

[0004] State of the art

[0005] 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 or nitrates and represent an important base fertilizer. These urea-based fertilizers can be combined with compounds of other elements such as potassium, manganese, phosphates, sulfur, sulfur compounds, selenium, and calcium.

[0006] Urea can be produced according to the simplified equations [1] and [2]:

[0007] 2 NH3+ CO2H2N-COONH4[1]

[0008] H2N-COONH4(NH2)2C0 + H2O [2]

[0009] The two starting materials, ammonia and carbon dioxide, can be provided 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").

[0010] 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).

[0011] 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]:

[0012] 3 H2+ N22 NH3+ 92.28 kJ [3]

[0013] The reactant nitrogen (N2) can be obtained, for example, by low-temperature air separation from ambient air.

[0014] The hydrogen is conventionally obtained via the “steam reforming process” according to equation [4]:

[0015] C n H 2m + n H2O (n+m) H2+ n CO [4]

[0016] In the subsequent “carbon dioxide conversion”, a further conversion takes place according to equation [5]:

[0017] CO + H20 CO2+ H2[5] The carbon dioxide (CO2) produced according to equation [5] is preferably used as a carbon dioxide source for urea synthesis according to equations [1] and [2].

[0018] According to equation [4], fossil fuels, usually methane from natural gas, serve as a feedstock for hydrogen production. Due to limited resources and the numerous problems resulting from climate change, a reduction in the consumption of fossil fuels, such as natural gas, is being pursued worldwide.

[0019] One approach regarding ammonia and urea synthesis is the construction of "green" ammonia plants ("gNH3 plants") that are at least partially powered by "green" hydrogen ("gH2") from renewable sources. In this way, ammonia could be used as a carbon-free energy storage medium for renewable (regenerative) energies. Therefore, a sharp increase in demand for "green" ammonia (gNH3) is expected in the coming years.

[0020] However, few or no gNH3 projects have been realized to date, as the very high investment costs (CAPEX - capital expenditure) of a gNH3 plant only very rarely justify its economic viability. These investment costs include not only the costs of the renewable energy source (wind farm, solar, hydro, etc.), electrolysis, and the NH3 cycle, but also, to a large extent, the costs of the plant's overall operation and infrastructure.

[0021] It should be noted that a universally applicable requirement and a universally applicable solution are not possible. The varying boundary conditions, such as the availability, fluctuations and costs of renewable energy, geographical location, existing infrastructure, and locally varying legal standards, necessitate flexible approaches to increase the economic viability of gNH3 plants.

[0022] The present invention therefore aims to provide a green NH3 plant based on conventional technology, which, by utilizing an existing grey NH3 plant, enables a reduction in investment and / or operating costs, thus improving the economic efficiency of the construction and operation of green NH3 plants.

[0023] Inventive solution

[0024] The problem of the invention is surprisingly solved by a green ammonia synthesis plant according to claim i. Further advantageous embodiments are found in the dependent claims.

[0025] The invention further comprises a method for retrofitting a grey ammonia synthesis plant according to claim 14 and a plant assembly comprising a green plant according to the invention and a grey plant according to claim 17. Further advantageous embodiments are found in the respective dependent claims.

[0026] By combining the green plant ("green ammonia plant," "gNH₃ plant," "green NH₃ plant," "green ammonia synthesis plant") with a grey plant ("grey ammonia plant," "grey NH₃ plant," "grey ammonia synthesis plant"), synergies between the two plants can be exploited. For example, the green plant can at least partially utilize existing infrastructure of the grey plant, and / or units or material flows from the grey plant can be used for the green plant, or vice versa. In particular, the green plant can be located in close proximity to an existing plant. Preferably, a green plant should only be combined with a grey plant at locations suitable for a sufficient and stable supply of renewable energy.

[0027] A "green plant" is defined here as a plant for the production of ammonia from hydrogen and nitrogen, in which "green hydrogen" is predominantly used as a feedstock – that is, hydrogen produced using renewable energy sources. This refers specifically to hydrogen produced using solar, wind, and / or hydropower, for example, by converting renewable energy sources into electricity, which is then used to power water electrolysis. The hydrogen production, as well as any conversion of renewable energy sources into electricity, can take place within the green plant itself or externally, with the green hydrogen being supplied to the plant from an external source, such as via a pipeline network or tank trucks.

[0028] Accordingly, a "grey plant" is defined here as a plant for the production of ammonia from hydrogen and nitrogen, in which "grey hydrogen" is predominantly used as a reactant—that is, hydrogen produced using hydrocarbons. This refers in particular to hydrogen produced from hydrocarbons via steam reforming, autothermal reforming, or partial oxidation, usually followed by a water-gas shift reaction (carbon monoxide conversion). This also includes grey hydrogen in which the resulting carbon dioxide is partially or completely captured (and thus separated and stored; sequestered) and does not enter the atmosphere (also called "blue hydrogen").

[0029] "Combining" here means that the green and gray plants are coupled. The two plants are therefore not completely independent of each other. This coupling can be mechanical, fluidic, and / or electrical, for example. Thus, the green and gray plants can be connected in such a way that mutual mass and heat exchange between them is possible, and parts of the infrastructure are shared by both plants. This can include supply via a shared infrastructure and / or the shared use of at least one plant unit, at least one process, and / or at least one material flow.

[0030] "In close proximity" here means that the combination can be achieved with minimal losses, particularly energy losses such as heat losses and, where applicable, compression energy losses. Especially if at least one material flow is transferred between the two systems, undesirable energy losses are to be expected at excessively large distances. For example, close proximity could mean a minimum distance between the green and the gray systems of less than 5 kilometers, preferably less than i kilometers, and most preferably less than 500 meters.

[0031] The green plant may also be configured to mix hydrogen from H2 recovery from a purge gas of the grey plant with a hydrogen stream of the green plant and / or to mix hydrogen from electrolysis of the green plant with a hydrogen stream or a fuel gas stream of the grey plant.

[0032] The addition of hydrogen recovered from the purge gas of the conventional plant allows for the compensation of fluctuations in the hydrogen production of the renewable energy plant. In the event of an interruption in the renewable energy plant's hydrogen production, for example, due to insufficient renewable energy availability, this enables the plant to operate, at least at low loads. Low load is defined here as, for example, a partial load of less than 15%, preferably less than 10%, and most preferably less than 5% of the renewable energy plant's output. Furthermore, the need for a costly hydrogen storage facility can be avoided, or at least a smaller hydrogen storage facility can be built for the renewable energy plant.

[0033] Blending hydrogen from the green plant into a hydrogen stream or a fuel gas stream from the grey plant can be particularly advantageous if the available electrical energy from renewable sources is only sufficient for part-load operation of less than 10% and / or if hydrogen transfer from the grey plant to the green plant is not permitted due to regulations or requirements. In this case, the green plant can switch to hot standby mode, and any excess hydrogen in the green plant can be used in the grey plant, for example, as a substitute for natural gas in a reformer. Furthermore, the steam generation system of the green plant can be configured to operate at a pressure level, particularly a medium pressure (MD, typically from 35 bar to 80 bar, preferably from 40 bar to 60 bar), similar to that of the grey plant.The green system can be configured to supply superheated or saturated steam at the appropriate pressure to a power generator, a steam line, and / or a machine drive of the gray system. The invention thus enables the thermal energy of the green system to be used either to drive machines of the gray system or to provide electrical energy, without requiring a separate turbine-generator unit for the green system. For supplying the medium-pressure steam, the green system can have a suitable connection, particularly a pipe connection, to the gray system. This connection can preferably be thermally insulated. Furthermore, the steam generated in the green system, for example, medium-pressure steam, can of course also be used to extract heat from the green system to the gray system.

[0034] The green plant can be configured to supply oxygen from an electrolysis process within the green plant and / or oxygen-enriched air from an air separation unit within the green plant to the gray plant, for example, to enrich combustion and / or process air. In existing green plants, the oxygen from electrolysis is a byproduct, as is the oxygen-enriched air from the air separation unit. Therefore, combining the green and gray plants allows for the further utilization of the oxygen or oxygen-enriched air, as well as reducing natural gas consumption and thus CO2 emissions from the gray plant.

[0035] The green system can be preferentially designed and configured to determine the available amount of oxygen and to calculate and specify the oxygen supply to the gray system in such a way that fluctuations in the oxygen availability of the green system do not affect, or at least do not negatively affect, the operation of the gray system. Green systems are characterized by a fluctuating availability of renewable energy, for example, due to weather conditions, and thus of the H2 and O2 produced by electrolysis. Gray systems, on the other hand, are not designed for significant fluctuations in operation. Determining the oxygen availability—even in the form of oxygen-enriched air—and calculating and specifying the oxygen supply, however, enables the control or regulation of the oxygen supply so that the processes in the gray system are not affected.In particular, it may be possible to limit the amount of oxygen supplied, either absolutely or relatively in relation to the total oxygen flow of the grey plant.

[0036] Furthermore, the green plant can alternatively or additionally be designed and equipped to utilize a start-up heater and / or hot gas streams, for example, from a flue gas duct, from methanization, or even superheated high-pressure steam (typically from 80 bar to 130 bar) from the gray plant, to preheat an inlet stream into a converter of the green plant. This is particularly advantageous for commissioning, restarting, and hot standby operation of the green plant, as no electric or combustion gas-powered heater is then required for these phases. Especially when using hot streams from the gray plant, the spatial proximity between the green and gray plants must be designed to minimize heat losses.

[0037] Preferably, the green system can be designed and configured to utilize at least one unit of the gray system. This avoids duplicating this unit in the green system. For example, the green system can have a connection, particularly a fluidic one, with the gray system, preferably a pipe connection.

[0038] A unit, in this context, refers to, for example, a component, a part, or a functional group of the green or gray plant. This can also be or comprise a plant unit or a plant section.

[0039] The at least one unit can be or comprise a raw water, boiler water, or cooling water treatment system, an instrument air generation system, a flare, a wastewater treatment system, a power generation system (in particular comprising a turbine and a generator), an NH3 tank, a compressor, a storage tank, a heat exchanger, a heater, a cooler, a pipeline, and / or a heat recovery system from the grey plant. For example, in the case of combined use of raw water, boiler water, or cooling water treatment, an existing cooling tower can be used and / or one or more cooling water pumps can be saved by connecting a raw water, boiler water, and / or cooling water circuit of the green plant to a corresponding circuit of the grey plant.

[0040] Furthermore, it can be planned, for example, that the green plant has a fluidic connection to the NH3 tank of the gray plant, so that a quantity of NH3 produced by the green plant can be stored in the NH3 tank of the gray plant. This eliminates the need for separate logistics, including, for example, an NH3 tank, transport routes, etc., for the green NH3 (i.e., the ammonia produced in a green NH3 plant). The complexity of the green plant, as well as investment and operating costs, can thus be reduced.

[0041] Preferably, the green system is designed and configured to record the quantity of NH3 supplied by the green system (i.e., to capture information about the quantity of NH3 supplied by the green system). This allows documentation, for example for certification purposes, of how much green NH3 is stored in the shared NH3 tank. The invention thus enables the use of both the existing NH3 tank and the entire existing NH3 infrastructure of the gray system. This is both economically and environmentally more efficient than requiring a separate NH3 infrastructure for the green system. For recording and capturing the supplied quantity of green NH3, the green system can, for example, include appropriate sensors and a storage medium, with the supplied quantity of green NH3 being stored on the storage medium.

[0042] Preferably, the green system is configured to feed a purge gas stream, as soon as it is available, to the gray system for treatment. This avoids the need to duplicate a device for treating the purge gas stream. To feed the purge gas stream to the gray system, the green system can, in particular, have a fluidic connection, for example, a pipe connection.

[0043] Preferably, the green system for preheating an inlet stream to a converter of the green system has a bypass to circumvent steam generation in the green system. Therefore, no electric heater or one powered by the combustion of a fuel gas is required for the ongoing operation of the green NH3 system.

[0044] Preferably, the green facility is designed and equipped to utilize at least some of the existing infrastructure of the grey facility during its operation. This avoids or at least reduces the need to create new infrastructure. This existing infrastructure could include, for example, a port, a road, a utility connection, a workshop, and / or an electrical grid. A utility connection could be, for instance, a water or gas supply. Thus, the green facility can, for example, be connected to or even integrated into the existing infrastructure. An electrical connection to an existing power grid can eliminate the need for an electrical battery storage system for the green facility, or at least allow it to be implemented with a reduced capacity.

[0045] The invention further relates to a method for retrofitting a gray ammonia synthesis plant. The method comprises constructing a green ammonia synthesis plant according to the invention, wherein the construction of the green plant includes combining it with the gray plant in such a way that mutual mass exchange and / or heat exchange between the two plants can take place and / or parts of an infrastructure can be shared by both plants.

[0046] The invention thus enables the production of green ammonia at reduced investment and / or operating costs. By combining the green plant with the conventional plant, synergies between the two systems can be exploited, allowing, for example, the reduction and / or reduction of the size of units in a prior art green plant.

[0047] In particular, combining green systems can involve connecting the green system to the infrastructure of the grey system, to at least one unit of the grey system, and / or to a material flow of the grey system. This allows the green system to utilize existing infrastructure, thus reducing the need to build new infrastructure. Furthermore, units of a green system, such as an electric battery, a hydrogen storage system, cooling water treatment, or a power generation unit consisting of a turbine and generator, can either be eliminated or at least designed to be smaller and therefore more cost-effective.By connecting to the material flows of the grey plant, material flows can be exchanged between the two plants, thus balancing fluctuations, particularly in the green hydrogen supply, and / or allowing an excess of a substance, such as oxygen from the electrolysis of the green plant, to be supplied to the other plant for use. Furthermore, energy, especially thermal energy, can also be transferred between the two plants via a connected material flow.

[0048] Preferably, the retrofitting prior to construction includes an evaluation of the site for the existing gray plant. This evaluation is specifically aimed at analyzing the suitability of the site for the construction of a green plant. Typical criteria for such an evaluation can include, for example, fluctuations and costs of renewable energies, the capacity of the existing gray plant and the green plant, legal (local) regulations for permissible carbon dioxide emissions from green ammonia plants, necessary or existing infrastructure, and the like. For instance, the availability of renewable energy can be assessed by considering, for example, annual solar irradiance or wind conditions. By evaluating the site, the invention enables the construction of the green plant to be carried out in an economically viable manner.

[0049] The invention further relates to a system comprising a green system and a grey system according to the invention. The green system and the grey system are combined in such a way that mutual mass exchange and / or heat exchange between the two systems can take place and / or parts of an infrastructure can be shared by both systems.

[0050] By combining the green and grey plants in this way, the integrated system allows for the utilization of synergies between the two. This results in savings in investment and / or operating costs and improves the economic viability of constructing and operating a green ammonia synthesis plant.

[0051] The details and advantages disclosed for the green plant according to the invention are transferable and applicable to the process and the plant system according to the invention, and vice versa.

[0052] 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.

[0053] They show:

[0054] Figure 1 shows a schematic flow diagram of a green ammonia synthesis plant according to the state of the art.

[0055] Figure 2 Synergy effects through the combination of a green ammonia synthesis plant according to the invention with a grey ammonia synthesis plant.

[0056] Figure 3 shows a schematic flow diagram of an embodiment of a green ammonia synthesis plant according to the invention. Figure 1 shows a schematic representation of a prior art green plant i for the production of green ammonia (gNH3) by providing renewable energy.

[0057] Plant i obtains the required hydrogen from electrolysis, specifically an alkaline water electrolysis unit 10. This unit is powered by an electrical supply (not shown). Since hydrogen for a green ammonia synthesis plant must be produced from renewable sources, the power supply can be generated from sources such as wind, solar, or hydropower, or from a grid or island grid supplied by renewable energy sources. To ensure a sufficient power supply for plant 1 during periods of insufficient renewable energy, the power supply can include a battery. Furthermore, the battery allows excess electrical energy to be stored for later use during periods of power shortage.

[0058] The hydrogen produced in the alkaline water electrolysis unit 10 is, after initial compression to approximately 8 bar in an H2 compressor 11, either fed to a synthesis cycle or, via a multi-stage hydrogen storage compression system (here exemplified by two hydrogen storage compressors 21, which together can also form a single multi-stage hydrogen storage compressor), fed to a hydrogen storage system 20 of the plant. In the hydrogen storage system 20, the hydrogen passes through two hydrogen storage compressors 21 before being fed to a hydrogen storage reservoir 22. A de-oxo reactor 23 is also arranged between the two hydrogen storage compressors 21 to remove oxygen from the hydrogen. At the inlet to the hydrogen storage reservoir 22, the hydrogen has a pressure of approximately 200 bar.

[0059] Furthermore, the hydrogen storage system includes four valves 24, 25, and 26, which regulate the supply of hydrogen to and discharge from the hydrogen storage tank 22. Thus, depending on demand, the hydrogen produced in the electrolysis unit 10 can be supplied to the hydrogen storage tank 22 by opening valve 24, or bypassed by closing valve 24. Valve 25 regulates the flow from the compressor 21 into the hydrogen storage tank 22, and valves 26 regulate the flow of hydrogen discharged from the hydrogen storage tank 22.

[0060] Before the hydrogen from hydrogen storage 20 is fed to the actual ammonia synthesis via valves 26 and / or directly from electrolysis 10 via connection 12, nitrogen provided in an air separation unit 13 is added to it. The nitrogen-hydrogen mixture is then compressed in the multi-stage synthesis gas compression unit (here, the two synthesis gas compressors 31, 32, which together can also form a single multi-stage synthesis gas compressor) and oxygen is removed between the two synthesis gas compressors 31, 32 in a second de-oxo reactor 33. Upstream of the second de-oxo reactor 33, the gas mixture has a pressure of, for example, approximately 40 bar, and downstream of the second synthesis gas compressor 32, a pressure of 140 bar. The gas mixture is then fed to a recirculating gas, typically in or upstream of an ammonia separator 40.

[0061] The circulated gas is compressed again in a further compressor 41, heated in a heat exchanger 42, and then fed to a converter 43 where hydrogen and nitrogen react in an equilibrium reaction to form ammonia. The reacted circulated gas leaves the converter 43, passes through a steam superheater 44 and a waste heat boiler 45, and then through the heat exchanger 42 again, before reaching the ammonia separator 40 once more (after further heat exchangers, not shown here). The ammonia obtained in the converter 43 can then be made available at a discharge 46. The ammonia can subsequently be stored or used for further applications, such as urea production. The circulated gas section has a control valve 47 through which a portion of the circulated gas can be discharged before the ammonia separator 40. This allows the ammonia concentration in the converter 43 to be adjusted, for example, to regulate the load of plant 1.Furthermore, an electric heater 48 is provided here to set a temperature at the inlet of the converter 43.

[0062] The superheater 44 and the waste heat boiler 45 are in turn supplied with boiler water, generating steam which can then be fed as a high-pressure stream to a turbine 51. The turbine 51 drives a generator 52 to produce electricity.

[0063] Furthermore, the ammonia separator 40 has a cooling system 49. Cooled coolant flows from the cooling system 49 into the ammonia separator 40, is heated there, and then fed back to the cooling system 49 to cool the coolant.

[0064] Due to the complexity of such a green plant 1, there is a very high investment requirement, for example, for the provision of ammonia tanks. Furthermore, there are also very high operating costs and / or transport costs, for example, for the removal and onward transport of the produced ammonia.

[0065] Therefore, the object of the invention is to provide a green plant 1 that has lower investment, transport, and / or operating costs by leveraging synergies between the green plant 1 and an existing gray plant. For this purpose, a green plant 1 according to the invention is combined with a gray plant. Figure 2 shows synergy effects that can be achieved through such a combination of the green plant 1 according to the invention and a gray plant 100. Units of the gray plant 100 are shown in the upper half, and units of the green plant 1 are shown below the dividing line in the lower half.

[0066] The oxygen obtained in the alkaline hydrogen electrolysis unit 10 and in the air separation unit 13 of the green plant 1 can be used as combustion air in a primary reformer 61 or as process air in a secondary reformer 62 of the grey plant 100. Alternatively or additionally, the oxygen can also be provided for other purposes, for example, for ventilation 65 or other downstream processes of the grey plant 100, such as nitric acid production, in which NH3 then reacts not with air but with oxygen-enriched air.

[0067] Conversely, hydrogen from H2 recovery unit 63 of the gray plant 100 can be blended with the green hydrogen from the alkaline hydrogen electrolysis unit 10. This can mitigate fluctuations in the hydrogen supply from the hydrogen electrolysis unit 10, which is powered by electricity generated from renewable energy sources. Furthermore, blending hydrogen from the gray plant 100 allows the green plant 1 to operate at a low load, for example, at 10% of its nominal load, thus avoiding or at least reducing the frequency of switching the green plant 1 into hot standby mode.

[0068] If necessary, purge gases from green plant 1 can be treated in grey plant 100, thus eliminating the need to duplicate a corresponding device in green plant 1. Furthermore, ammonia (NH3) can be transferred from green plant 1 to grey plant 100, allowing the NH3 infrastructure of grey plant 100 to be utilized by green plant 1.

[0069] Finally, it can be arranged that the boiler feedwater for the waste heat boiler 45 of the green plant 1 is supplied by the gray plant 100. This allows, for example, the use of corresponding pumps and boiler feedwater treatment systems, eliminating the need for additional equipment in the green plant 1. The superheated steam generated in the waste heat boiler 45 can then be transferred back to the gray plant 100 for further use, such as power generation, machine operation, or similar applications. Similarly, the cooling water for a cooling device 50 of the green plant 1 can be supplied by the gray plant 100. This allows the cooling water to be cooled in a shared cooling water treatment system 64, purified if necessary, and then returned to the cooling circuit.

[0070] Figure 3 shows an exemplary embodiment of a green plant 1 according to the invention. This plant 1 was constructed here to retrofit a grey plant 100. Before construction, the location of the grey plant 100 was evaluated. Construction is only economically viable if the location is suitable for operating a green plant 1. When evaluating existing or usable renewable energy sources, the infrastructure of the grey plant 100, in particular its condition, can also be included in the evaluation.

[0071] The construction of the green plant 1 involves combining it with the gray plant 100. For example, plant 1 shown in Fig. 3 does not have a hydrogen storage system 20. Instead, a connection 81 is provided through which hydrogen from the gray plant 100 can be supplied to the green plant 1. This hydrogen can, for example, originate from an H2 recovery unit 63 of the gray plant 100, in which a purge gas is treated. In current gray plants 100, the H2 recovered in this way can amount to approximately 3% of the plant capacity. The gray plant 100 shown in Fig. 2, for example, has a plant capacity of 2200 metric tons (tato) of NH3 per day. For the green plant 1 shown in Fig. 3, with a plant capacity of 660 metric tons (tato), a partial load of 10% can thus be achieved solely with the hydrogen supplied from the gray plant 100, which was recovered from the purge gas.Thus, by combining the components via connection 81, the reliability of the green system 1 can be increased, and a more stable operation can be achieved, since fluctuations in the hydrogen supply by the electrolysis unit 10 can be compensated for by hydrogen from connection 81.

[0072] Furthermore, the system 1 shown in Fig. 3 has an oxygen discharge 80 through which excess oxygen from the electrolysis 10 or oxygen-enriched air from the air separation unit 13 can be supplied to the gray system 100. This allows the excess oxygen to be utilized and, on the other hand, reduces, for example, natural gas consumption and CO2 emissions in the primary reformer 61 and / or the secondary reformer 62 of the gray system 100 by leaning out the combustion and / or process air.

[0073] System 1 may include a control or regulation device (not shown) that regulates the oxygen discharged via oxygen outlet 80, as system 100 (grey) is designed for stable operation. To prevent fluctuations in the oxygen supply, oxygen outlet 80 may have a control valve and / or a portion of the discharged oxygen may be vented via an outlet valve or used for ventilation in either system 1 or 100.

[0074] Furthermore, Plant 1 is designed to feed the green ammonia via ammonia discharge 46 to an NH3 tank in the gray plant 100. This eliminates the need for separate NH3 logistics for the green plant 1. Specifically, the amount of ammonia transferred from the green plant 1 to the gray plant 100 is recorded and documented. This can be done manually, but preferably automatically using appropriate sensors and an electronic storage medium. This allows for tracking the amount of green ammonia being fed in.

[0075] The system 1 shown in Fig. 3 also features a boiler water supply 82 and a steam exhaust 83. This eliminates the need for a separate power generation system from turbine 51 and generator 52 compared to the green system 1 shown in Fig. 1. Instead, the steam transferred to the gray system 100 via the steam exhaust 83 can be used there for power generation or other purposes, such as driving machinery. A separate boiler water treatment system is also unnecessary. Instead, the boiler water is cooled in the gray system 100 and returned to the heat recovery boiler 45.

[0076] The system 1 in Fig. 3, compared to the system 1 in Fig. 1, has a bypass 71 around the superheater 44 and the waste heat boiler 45. An actuator 72 allows the amount of recirculated gas bypassed, thus bypassing the superheater 44 and the waste heat boiler 45. The inlet temperature of the recirculated gas to the converter 43 can therefore be adjusted by controlling the amount of recirculated gas bypassed, so that the electric heater 48 can be switched off, at least during operation of the system 1. To avoid using the electric heater 48 during commissioning or restarting of the system 1 and thus save on its cost, further embodiments (not shown) can provide for heating the recirculated gas via a start-up heater of the gray system 100 or in a heat exchanger using hot gases from the gray system 100.This would require a further connection between grey system 100 and green system, which must have appropriate thermal insulation, especially when heated with hot gases.

[0077] In other embodiments not shown, it is also possible to eliminate the superheater 44. For this to work, however, the high-pressure steam exiting the converter 43 would have to be transferred directly to the gray system 100 for further processing or heat removal. While this would eliminate the need for the separate superheater 44, this variant is particularly suitable for very short distances between the green system 1 and the gray system 100, as otherwise excessive heat losses would be expected.

[0078] 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.

[0079] Reference symbol list

[0080] 1 Green plant for ammonia synthesis Alkaline hydrogen electrolysis unit

[0081] H2 compressor

[0082] Connection

[0083] Air separation plant 0 Hydrogen storage 1 Hydrogen storage compressors 2 Hydrogen storage 3 De-oxo reactor 4, 25, 26 Valves L 32 Synthesis gas compressors 3 Second de-oxo reactor 0 Ammonia separator 1 Recirculating gas compressor 2 Heat exchanger 3 Converter Superheater

[0084] waste heat boiler

[0085] Ammonia removal

[0086] Control valve

[0087] Electric heater

[0088] cooling

[0089] Cooling device

[0090] turbine

[0091] Generator (G)

[0092] Primary reformers

[0093] Secondary reformers

[0094] H2 recovery

[0095] Cooling water treatment

[0096] ventilation

[0097] Bypass actuator, oxygen removal, hydrogen supply, boiler water supply, steam removal, grey ammonia synthesis plant

Claims

Patent claims 1. A plant system comprising a green plant for ammonia synthesis (1) from hydrogen and nitrogen and a grey plant for ammonia synthesis (100) from hydrogen and nitrogen, wherein the green plant (i) is configured to use predominantly hydrogen produced using renewable energy sources as a feedstock, and the grey plant (100) is configured to use predominantly hydrogen produced using hydrocarbons as a feedstock, characterized in that the green plant (i) and the grey plant (100) are combined in such a way that mutual mass exchange and / or heat exchange between the two plants can take place and / or parts of an infrastructure can be shared by both plants.

2. System assembly according to claim 1, characterized in that the green system (i) is configured to add hydrogen from an H2 recovery (63) of a purge gas of the grey system (100) to a hydrogen stream of the green system (1) and / or to add hydrogen from an electrolysis (10) of the green system (1) to a hydrogen stream or a fuel gas stream of the grey system (100).

3. System according to claim 1 or 2, characterized in that a steam generation unit (44, 45) of the green system (1) is configured to operate at a pressure level, in particular a medium pressure (MD), such as prevails in the gray system (100), and that the green system (1) is configured to supply such superheated or saturated steam to a power generation unit, a steam engine and / or a machine drive of the gray system (100).

4. System assembly according to one of the preceding claims, characterized in that the green system (1) is designed to extract oxygen from to supply to an electrolysis (10) of the green plant (i) and / or oxygen-enriched air from an air separation plant (13) of the green plant (1) to the grey plant (100), for example for the enrichment of combustion and / or process air.

5. System according to claim 4, characterized in that the green system (1) is designed and configured to determine an available quantity of oxygen and to calculate and specify the oxygen supply to the grey system in such a way that fluctuations in the oxygen availability of the green system (1) do not have, or at least do not have a negative effect on, the operation of the grey system (100).

6. Plant assembly according to one of the preceding claims, characterized in that the green plant (1) is designed and equipped to use a start-up heater and / or hot gas streams, for example from a flue gas duct, from a methanization process or superheated high-pressure steam from the grey plant (100) to preheat the inlet stream to the converter (43), in particular during commissioning or restarting as well as in hot standby operation of the green plant (1).

7. System according to one of the preceding claims, characterized in that the green system (1) is designed and equipped to share at least one unit of the grey system (100).

8. Plant assembly according to claim 7, characterized in that the at least one unit may be or comprise a raw, boiler or cooling water treatment (64), an H2 recovery (63), an instrument air generation, a flare, a wastewater treatment, a power generation, an NH3 tank, a compressor, a storage, a heat exchanger, a heater, a cooler, a pipeline and / or a heat extraction from the grey plant (100). 9- System assembly according to claim 8, characterized in that the at least one unit is an NH tank and that the green system (i) is designed and equipped to store an NH quantity provided by the green system (1) in the NH tank of the grey system (too) and preferably to detect the NH quantity provided by the green system (i) and stored in the NH tank of the grey system (too).

10. System assembly according to one of the preceding claims, characterized in that the green system (i) is configured to supply a purge gas stream of the green system (1) for treatment in the grey system (IOO) of the grey system (100).

11. Plant assembly according to one of the preceding claims, characterized in that the green plant (1) has a bypass (71) for preheating an inlet stream into a converter (43) of the green plant (1) to bypass a steam generation (44, 45) of the green plant (1).

12. System according to one of the preceding claims, characterized in that the green system (1) is designed and equipped to utilize at least part of the existing infrastructure of the grey system (100) during the operation of the green system (1).

13. System according to claim 12, characterized in that at least one part of the existing infrastructure is a port, a road, a supply, a workshop and / or an electrical network.

14. Method for retrofitting a grey system (100) to Ammonia synthesis (100) from hydrogen and nitrogen with a green plant (1) for ammonia synthesis from hydrogen and nitrogen to obtain a plant network according to one of claims 1 to 13 such that a mutual exchange of mass and / or heat exchange between the two plants This can take place between them and / or parts of the infrastructure can be shared by both facilities. 15- Method according to claim 14, characterized in that combining comprises connecting the green plant (1) to an infrastructure of the grey plant (100), to at least one unit of the grey plant (100) and / or a material flow of the grey plant (100).

16. Method according to claim 14 or 15, characterized in that the retrofitting prior to erection comprises an evaluation of a location of the grey plant (100). 26 / 27

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