WO2025190800A1

WO2025190800A1 - Modular ammonia production plant

Info

Publication number: WO2025190800A1
Application number: PCT/EP2025/056268
Authority: WO
Inventors: Martina TRINI; Sergio GHEZZI; Simone CORBO; Giovanni CAMARDA; Yeidy Sorani MONTENEGRO CAMACHO; Ali MANSOURI
Original assignee: Nuovo Pignone Technologie SRL
Current assignee: Nuovo Pignone Technologie SRL
Priority date: 2024-03-15
Filing date: 2025-03-07
Publication date: 2025-09-18
Anticipated expiration: 2026-09-15

Abstract

The modular green ammonia plant comprises a nitrogen production module having an air inlet and a nitrogen outlet, and a hydrogen production module having a water inlet and a hydrogen outlet. The modular green ammonia plant further comprises an ammonia synthesis module comprising an ammonia synthesis reactor having an inlet adapted to receive pressurized syngas containing nitrogen and hydrogen, and an ammonia-rich gas outlet.

Description

MODULAR AMMONIA PRODUCTION PLANT

DESCRIPTION

TECHNICAL FIELD

[0001] The present disclosure concerns ammonia production plants. Specifically, embodiments disclosed herein concern green modular ammonia production plants.

BACKGROUND ART

[0002] Ammonia (NH3) is currently used in a variety of applications in several industrial fields, and is also mainly used as fertilizer in agriculture.

[0003] The most commonly used process for ammonia production is the so-called Haber-Bosch process. The process converts atmospheric nitrogen (N2) to ammonia (NH3) by reaction with hydrogen (H2) in an ammonia synthesis reactor, usually using a metal, such as iron, ruthenium as catalyst under high temperature and pressure conditions. The primary reaction is:

N2+3H2 2NH₃

[0004] Conventional ammonia synthesis poses significant environmental concerns due to its reliance on fossil fuels, from which hydrogen is obtained through steam reforming and water gas shift reaction. Steam reforming involves the reaction of hydrocarbons, predominantly methane (CH4), with steam, resulting in the production of hydrogen and carbon monoxide, as described by the following

CH₄ + H2O CO + 3H₂

[0005] Carbon monoxide is converted into carbon dioxide and hydrogen through water gas shift reaction according to the formula

CO + H2O CO2 + H2

[0006] To reduce the environmental impact of ammonia production processes, methods have recently been introduced where hydrogen is produced through water electrolysis instead of chemical conversion from hydrocarbons. This reduces the environmental impact by eliminating the release of carbon dioxide in the hydrogen generation process. Further reduction in harmful emissions occurs if the electricity needed for water electrolysis is generated from renewable sources, for instance using electricity from photovoltaic plants, or wind farms, from hydropower or geothermal power, and the like. Ammonia produced using renewable sources for the hydrogen required in the ammonia synthesis reaction is termed “green ammonia”.

[0007] A typical green ammonia plant consists of a front end, where hydrogen produced by electrolysis is combined with nitrogen from an ASU (Air Separation Unit) to generate a gas mixture comprising approximately 75% nitrogen and approximately 25% hydrogen. In the present specification, the gas mixture containing hydrogen and nitrogen will be referred to shortly also as “syngas”. The gas mixture, i.e., the syngas, is then compressed and enters the back end, passing through an ammonia reactor which produces gaseous ammonia. Subsequently, an ammonia refrigeration cycle separates the produced ammonia from unreacted gaseous hydrogen and nitrogen.

[0008] The assets and plant design are tailored for each project, utilizing a dedicated layout built on a foundation, in a so-called stick-built plants.

[0009] Designing a large-scale ammonia production plant (>600 tons per day) demands extensive customization efforts and dedicated studies tailored to the specific project, resulting in lengthy procedures during feasibility studies, pre-FEED, and FEED phases.

[0010] A different approach to plant design aimed at reducing these drawbacks would be welcomed in the art.

SUMMARY

[0011] According to one aspect, disclosed herein is a modular green ammonia plant comprising a nitrogen production module having an air inlet and a nitrogen outlet, and a hydrogen production module having a water inlet and a hydrogen outlet. The modular green ammonia plant further comprises an ammonia synthesis module comprising an ammonia synthesis reactor having an inlet adapted to receive pressurized syngas containing nitrogen and hydrogen, and an ammonia-rich gas outlet. The ammonia synthesis module also has one or more inlets to receive hydrogen and nitrogen which shall be converted into ammonia. In some embodiments the ammonia synthesis module has separate inlets for hydrogen and nitrogen. In other embodiments, the ammonia synthesis module comprises a common inlet, which receives a gas mixture containing nitrogen and hydrogen. The common inlet can be arranged upstream or downstream of a compression module adapted to compress the gas mixture containing hydrogen and nitrogen, depending on whether the compression module is part of the ammonia synthesis module or is arranged in a separate module upstream of the ammonia synthesis module.

[0012] As mentioned, “green ammonia” is ammonia produced using renewable sources for production of the hydrogen required in the ammonia synthesis reaction. Similarly, a green ammonia plant as understood herein is a plant adapted to produce green ammonia, i.e. wherein the hydrogen required for the ammonia synthesis process is produced using energy from renewable energy sources.

[0013] Further features and embodiments are described here below and set out in the appended claims.

[0014] In embodiments disclosed herein, the plant further includes a gas compression module, which receives a mixture containing hydrogen and nitrogen, and wherein the pressure of the nitrogen and hydrogen mixture is brought to the pressure required by the ammonia synthesis reactor.

[0015] The ammonia synthesis reactor delivers an ammonia-rich gas, which can be processed in an ammonia purification module to remove unreacted hydrogen and nitrogen therefrom.

[0016] The ammonia purification module and the compression module can be variously arranged as part of the ammonia synthesis module, or separately therefrom, as stand-alone modules.

[0017] The plant may further include an energy recovery system, which can be configured as one or more modules or sub-modules, as will be described below in greater detail.

[0018] As understood herein, a sub-module is a module forming part of a larger module.

[0019] According to the present disclosure, the green ammonia production plant uses modules and sub-modules, each module capable of having one or more inlets and one or more outlets for connection to adjacent modules. Outlets serve as the inlets for subsequent modules. A dedicated control system manages the fluid flows as well as energy flows, rendering the system flexible to accommodate production increases and simplifying upgrade procedures.

[0020] The distribution of various plant components among modules and sub-modules can vary across different embodiments, as described below. This distribution may depend, for example, on the plant size and therefore on the size of resulting modules and how they are transported to the site of destination. Installability, commissioning and maintainability are other reasons for having different module configurations. Additionally, the choice may be influenced by the origin of the equipment pieces comprised in the plant. Grouping components manufactured by the same provider into the same modules can be advantageous, allowing the provider to assemble and test the module, a sub-unit of the full plant, at the manufacturing site, thus avoiding subsequent disassembly. Upon installation, each module will only need to be fluidly coupled to adjacent modules, without requiring further testing of the already assembled devices within the module. In some cases, only minor testing operations may be required.

[0021] Furthermore, the modules can be equipped with embedded cranes and bridges, enabling comprehensive maintenance operations without reliance on external activities. This approach aims to overcome the limitations imposed by customized designs, enhancing adaptability to various ammonia projects. By utilizing modular components, these modules can not only be assembled to construct a plant but also effectively manage the plant's capacity.

[0022] Maintenance is simplified, as there is no reliance on external assets and equipment. The plant is designed such that maintenance can be carried out on the module itself. Traditional plant capacity expansion is constrained by the high degree of plant customization. Conversely, the modular solution approach disclosed herein enables capacity increases by adding modules. [0023] One, some or each module may include at least one base plate. For instance, all of the equipment of a module can be installed on a single base plate forming a skid. As used herein, a skid is the unit comprised of a base plate and of the relevant equipment installed onboard the base plate.

[0024] In some embodiments, at least one, some or each module may include two or more base plates and each base plate can form, along with the relevant equipment installed thereon, a skid.

[0025] As described in more detail below, a fluid or electrical coupling can be provided between two or more modules, i.e., two or more skids of the plant. The electrical coupling can provide a power or data connection. In advantageous embodiments of the present disclosure, the modules or skids are coupled to each other via plug-in couplings, both for providing a fluid connection and for providing an electrical or power connection therebetween.

[0026] Each skid or module can have a base plate with a rectangular footprint. Plugin connections, for example for fluid or electric couplings between modules of the plant, can be positioned along one, some or each side of the rectangular footprint. Connections, such as plug-in connections, can further be provided above or below the base plate of the skid or module.

[0027] Further features and embodiments of plants according to the present disclosure are described below, reference being made to the attached drawings, and are outlined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Reference is now made briefly to the accompanying drawings, in which: Figs.1 to 20 show schematics of various embodiments of green ammonia production plants according to the present disclosure.

DETAILED DESCRIPTION

[0029] A first embodiment of a modular green ammonia production plant according to the present disclosure is shown in Fig.l. The modular green ammonia production plant 1 comprises a nitrogen production module 3 having an air inlet 3.1 and a nitrogen outlet 3.2. The nitrogen production module 3 can include any known device or system adapted to separate nitrogen from air, i.e., any kind of air separation unit (ASU).

[0030] In some embodiments, the nitrogen production module 3 is partly or preferably fully powered by renewable energy (RE) as schematically shown at 3.3. The renewable energy can be generated by any renewable source of energy, such as solar or wind energy, geothermal energy, or hydropower, for instance, which is suitably converted into electric energy or other forms of energy required by the nitrogen production module.

[0031] The green ammonia production plant 1 further comprises a hydrogen production module 5. The hydrogen production module 5 comprises a water inlet 5.1 and a hydrogen outlet 5.2 and can be powered by electric energy generated through a renewable energy source, as mentioned, and schematically shown at 5.3. Water can be in liquid form or in vapor form, i.e., as steam. As understood herein and in the attached claims, therefore, the term “water” also includes steam.

[0032] The nitrogen outlet 3.2 and the hydrogen outlet 5.2 are fluidly coupled to a nitrogen inlet 7.1 and to a hydrogen inlet 7.2 of an ammonia synthesis module 7 wherefrom ammonia (NH3) is delivered at an ammonia outlet 7.3. Based on the modular approach disclosed herein, the hydrogen production module 5 and the nitrogen production module can be constructed and tested in one site, e.g., the workshop site or fabrication shop site, and then delivered to the final site of use. Each skid or module can be functionally checked prior to being shipped to the final site and certified. At the final site, the hydrogen outlet 5.2 and the nitrogen outlet 3.2 are simply coupled to the respective inlets of the ammonia synthesis module 7, embodiments whereof will be described here below. The entire wiring and piping of the modules mentioned above can be set up and tested prior to transportation to the final site of use, where the modules are connected to one another, to form the complete ammonia production plant. This also applies to other modules which will be described below in several embodiments.

[0033] The ammonia synthesis module 7 is powered by energy which can be generated using renewable energy from a renewable energy source, as shown at 7.4. [0034] The ammonia synthesis module 7 can in turn include a plurality of sub-modules. In the exemplary embodiment of Fig.1 the ammonia synthesis module 7 comprises a gas mixture compression module 9, fluidly coupled to the nitrogen inlet 7.1 and to the hydrogen inlet 7.2 and comprising at least one gas mixture compressor. As previously mentioned, the gas mixture containing predominantly nitrogen and hydrogen will also be referred to herein as "syngas" for brevity. Therefore, the gas mixture compressor and the gas mixture compression module 9 will be referred to herein also as “syngas compressor” and “syngas compression module 9”, respectively.

[0035] In the embodiment of Fig.1 the syngas compression module 9 is configured as a syngas compression sub-module 9 of the ammonia synthesis module 7.

[0036] The syngas is compressed by the compression sub-module 9 at a pressure adapted for conducting the ammonia synthesis reaction in the ammonia synthesis reactor 11 and is delivered therein through an inlet 11.1 of the ammonia synthesis reactor 11.

[0037] The syngas compressor sub-module 9 may include a mixing section, not shown, where nitrogen from the nitrogen production module 3 and hydrogen from the hydrogen production module are mixed to form the gas mixture (syngas), which is pressurized by the syngas compressor module 9 at the required pressure for subsequent ammonia synthesis reaction in an ammonia synthesis reactor 11, installed in the ammonia synthesis module 7. The syngas compression sub-module 9 is fluidly coupled to an inlet 11.1 of the ammonia synthesis reactor 11.

[0038] The ammonia synthesis reactor generates a flow of ammonia-rich gas, or gaseous flow, at high temperature and high pressure. The ammonia-rich gas also contains residual, unreacted hydrogen and nitrogen, which shall be removed from the ammonia- rich gas.

[0039] The green ammonia production plant 1 further comprises an ammonia purification module adapted to be fluidly coupled to an ammonia-rich gas outlet 11.2 of the ammonia synthesis reactor 11.

[0040] In the embodiment of Fig.1, the ammonia purification module is configured as an ammonia purification sub-module 13 installed in, or forming part of, the ammonia synthesis module 7.

[0041] The ammonia purification module can be based on any available technology. For instance, the ammonia purification module 13 can be based on cryogenic distillation, scrubbing and chemical absorption in an absorption tower, pressure swing adsorption (PSA), temperature swing adsorption (TSA), membrane separation, or the like.

[0042] The ammonia purification module 13 is adapted to separate unreacted chemical species (N2 and H2) contained in the ammonia-rich gas delivered by the ammonia synthesis reactor 11. Through a return line 15, unreacted hydrogen and nitrogen separated by the ammonia purification module 13 are returned upstream, for instance to the syngas compression sub-module 9 for further processing.

[0043] In some embodiments, the ammonia purification module 13 can be embedded in, or form part of the ammonia synthesis reactor 11. This may be the case for instance when the ammonia synthesis reactor comprises a membrane reactor.

[0044] A modified embodiment of the green ammonia production plant 1 is shown in Fig.2.

[0045] Elements and components identical in the embodiments of Figs. 1 and 2 are denoted by the same reference numbers.

[0046] The main difference between the arrangement of Fig.2 and the arrangement of Fig.1 is that in the former the ammonia synthesis module 7 comprises a single inlet 7.5 adapted to receive syngas containing nitrogen and hydrogen. In other words, the mixture of nitrogen and hydrogen that constitutes syngas is formed before entering the ammonia synthesis module.

[0047] A yet further embodiment of the green ammonia production plant 1 is shown in Fig.3. The same reference numbers used in Figs. 1, 2 and 3 indicate the same elements or components of the plant 1.

[0048] The green ammonia production plant 1 of Fig.3 differs from the embodiment of Fig.2 mainly in that in Fig.3 the ammonia synthesis module 7 further comprises a mixing station 17 having a first inlet adapted to be fluidly coupled to the nitrogen outlet 3.2 of the nitrogen production module 3 and a second inlet adapted to be fluidly coupled to the hydrogen outlet 5.2 of the hydrogen production module 5. An outlet of the mixing station 17 forms the inlet 7.5 through which syngas is delivered to an inlet 9.1 of the syngas compression sub-module 9. The return line 15 fluidly couples the ammonia purification sub-module 13 with the mixing station 17.

[0049] Fig.4 illustrates a further embodiment of a green ammonia production plant 1 according to the present disclosure. The same reference numbers used in Fig.3 and in Fig.4 indicate the same elements or components of the green ammonia production plant. These elements and components will not be described again.

[0050] The embodiment depicted in Fig.4 differs from the one in Fig.3 primarily in terms of the configuration of the ammonia purification module. While in the embodiments of Figs.1 to 3, the ammonia purification module is configured as a sub-module 13 of the ammonia synthesis module 7, in Fig.4 the ammonia purification module is configured as a stand-alone module, again labeled 13. The ammonia purification module 13 of Fig.4 has an ammonia inlet 13.1 adapted to be fluidly coupled to the ammonia outlet 7.3 of the ammonia synthesis module and further includes an ammonia outlet 13.2, wherefrom purified ammonia is delivered. As described with regard to Figs. 1, 2 and 3 with respect to the coupling between the hydrogen production module 5, the nitrogen production module 1 and the ammonia synthesis module 7, this latter can be fluidly coupled to the stand-alone ammonia purification module 13 through a plug-in connection of respective inlet and outlet ducts, namely between the outlet 7.3 of the ammonia synthesis module 7 and the inlet 13.1 of the ammonia purification module 13. A further coupling between the ammonia synthesis module 7 and the ammonia purification module 13 is provided along the return line 15, which delivers residual unreacted nitrogen and hydrogen from the ammonia purification module 13 back to the ammonia synthesis module 7. The return line 15 may for example be divided into two portions, coupled by a flange connection, not shown, to allow quick coupling between a pre-assembled ammonia purification module 13 and a pre-assembled ammonia synthesis module 7. Hydrogen and nitrogen recovered from the ammonia purification module 13 and returned to the ammonia synthesis module can be delivered to the mixing station 17 and added to the main stream of hydrogen and nitrogen delivered by the nitrogen production module 3 and by the hydrogen production module 5. Alternatively, the reactants recovered from the ammonia recovery module 13 can be directly supplied to the syngas compression module 9. The entry point of unreacted nitrogen and hydrogen into the ammonia synthesis module 7 is contingent, for example, on the pressure within the return line 15.

[0051] In the embodiments described so far, the ammonia synthesis reactor 11 and the syngas compression sub-module 9 are configured as parts (sub-modules) of the ammonia synthesis module 7. In other embodiments, a different distribution of the functional parts of the green ammonia production plant 1 can be envisaged, as will be described in more detail below, still maintaining the concept of modular configuration of the plant.

[0052] An embodiment of the green ammonia production plant 1 with a different distribution of functional blocks among different modules is shown in Fig.5.

[0053] In the embodiment of Fig.5 the modular green ammonia plant 1 comprises a nitrogen production module 3 having an air inlet 3.1 and a nitrogen outlet 3.2. The nitrogen production module 3 can include any known device or system adapted to separate nitrogen from air, i.e., any kind of air separation unit (ASU).

[0054] In some embodiments, the nitrogen production module 3 is powered by renewable energy (RE) as schematically shown at 3.3. The renewable energy can be generated by any renewable source of energy, such as solar or wind energy, hydropower, or geothermal energy, which is suitably converted into electric or other forms of energy required by the nitrogen production module.

[0055] The green ammonia production plant 1 of Fig.5 further comprises a hydrogen production module 5. The hydrogen production module 5 comprises a water inlet 5.1 and a hydrogen outlet 5.2 and can be powered by electric energy generated through a renewable energy source, and schematically shown at 5.3.

[0056] The nitrogen outlet 3.2 and the hydrogen outlet 5.2 are fluidly coupled with respective nitrogen inlet and hydrogen inlet of a mixing station 17. In this embodiment, the mixing station 17 is installed as a functional component on a syngas compression module 21. Similarly, to the other modules of the plant 1, the syngas compression module 21 can be powered by renewable energy RE as shown at 21.1.

[0057] In this embodiment, the syngas compression module 21 comprises the mixing station 17 and a syngas compression sub-module, again labeled 9. The syngas compression sub-module 9 comprises a syngas inlet 9.1 and a syngas outlet 9.2, which is in turn fluidly coupled to an outlet 21.2 of the syngas compression module 21. As in the previously mentioned syngas compression sub-modules, the syngas compression module or sub-module can comprise one or more compressor stages in series, depending upon the required compression ratio. Moreover, the syngas compression module or sub-module may include one or more compressor packages, or compressors in parallel, for instance depending upon the required flowrate to be processed and/or in view a redundancy requirement to ensure operability of the system in case of fault or temporary unavailability of one of said compressors.

[0058] The outlet 21.2 of the syngas compression module 21 is fluidly coupled to an inlet 7.5 of an ammonia synthesis module 7, which can be powered with renewable energy (RE), see 7.4. In this embodiment, the ammonia synthesis module 7 comprises an ammonia synthesis reactor 11, but does neither include the syngas compression module 9 nor an ammonia purification sub-module, which in this embodiment is configured as a stand-alone ammonia purification module, again labeled 13, having an ammonia inlet 13.1 and an ammonia outlet 13.2. A return line 15 fluidly couples an unreacted gases outlet of the ammonia purification module 13 with an upstream section, in the embodiment of Fig.5 with the mixing station 17.

[0059] Reference 13.6 indicates a power supply of the ammonia purification module, which can supply power from a renewable energy source (RE), which is in general present in stand-alone ammonia purification modules in the various embodiments described herein.

[0060] With continuing reference to the previous figures, and specifically Fig.5, a further embodiment of a green ammonia production plant 1 according to the present disclosure is shown in Fig.6. The same reference numbers used in Fig.5 and in Fig.6 indicate the same elements or components of the green ammonia production plant 1. These elements and components will not be described again. [0061] The main difference between the embodiment of Fig.6 and the embodiment of Fig.5 is that in Fig.6 the ammonia purification module is again configured as a submodule 13 of the ammonia synthesis module 7, similarly to Figs. 1, 2 and 3. The remaining components are the same as described above in connection with Fig.5.

[0062] In each embodiment shown in Figs. 1 to 6 the ammonia purification module 13 can be removed and replaced by an ammonia purification section forming part of the ammonia synthesis reactor 11. In such case, the return line 15 will extend from the ammonia synthesis reactor 11 to the inlet 7.5 (Fig.2), to the mixing station 17 (Figs. 3, 4, 5, 6), or directly to the syngas compression sub-module 9.

[0063] In some embodiments, the green ammonia production plant 1 can include systems for energy recovery. Energy can be recovered in form of waste heat (thermal energy), pressure energy or both. The recovered energy can be used in one or more modules or sub-modules of the green ammonia production plant 1, or transferred to outer facilities or users. The recovered energy can be used as such, or converted into other forms of energy, such as mechanical or electric energy, as will be described below with reference to some exemplary embodiments.

[0064] An embodiment of a green power production plant 1 including energy recovery is shown in Fig.7. The same reference numbers used in Figs. 1 to 6 are used to designate the same or equivalent components and elements of the embodiment shown in Fig.7.

[0065] The modular green ammonia plant 1 of Fig.7 comprises a nitrogen production module 3 having an air inlet 3.1 and a nitrogen outlet 3.2. The nitrogen production module 3 can include any known device or system adapted to separate nitrogen from air, i.e., any kind of air separation unit (ASU).

[0066] In some embodiments, the nitrogen production module 3 is powered by renewable energy (RE) as schematically shown at 3.3. The renewable energy can be generated by any renewable source of energy, such as solar or wind energy, hydropower, geothermal energy, or the like, which is suitably converted into electric energy or other forms of energy required by the nitrogen production module.

[0067] The green ammonia production plant 1 further comprises a hydrogen production module 5. The hydrogen production module 5 comprises a water inlet 5.1 and a hydrogen outlet 5.2 and can be powered by electric energy generated through a renewable energy source, and schematically shown at 5.3.

[0068] Nitrogen and hydrogen outflowing from the nitrogen production module 3 and the hydrogen production module 5 are mixed to form syngas which is compressed and delivered to an ammonia synthesis module 7. In the embodiment of Fig.7, hydrogen and nitrogen are mixed in a mixing station 17 which has an outlet fluidly coupled to an inlet 9.1 of a syngas compression sub-module 9. In other embodiments, hydrogen and nitrogen can be delivered to separate inlets of the syngas compression sub-module 9, as shown in Fig.l, for instance.

[0069] In this embodiment, the mixing station 17 and the syngas compression submodule 9 are part of a syngas compression module 21. This latter includes an outlet 21.1, which receives compressed syngas delivered at an outlet 9.2 of the syngas compression sub-module 9. The outlet 21.1 of the syngas compression module 21 is fluidly coupled to an inlet 7.5 of an ammonia synthesis module 7. The syngas compression module 21 can be powered by energy (RE) from a renewable source, as shown at 21.1.

[0070] The ammonia synthesis module 7 is powered by energy which can be generated using renewable energy from a renewable energy source, as shown at 7.4.

[0071] The ammonia synthesis module 7 can in turn include one or more sub-modules. In the exemplary embodiment of Fig.7, the ammonia synthesis module 7 comprises an ammonia synthesis reactor 11. Syngas, i.e., the gas mixture from the mixing station 17, is compressed by the compression sub-module 9 at a pressure adapted for conducting the ammonia synthesis in the ammonia synthesis reactor 11 and is delivered therein through an inlet 11.1 of the ammonia synthesis reactor 11.

[0072] The green ammonia production plant 1 of Fig.7 can comprise an ammonia purification module 13 adapted to be fluidly coupled to an ammonia-rich gas outlet 11.2 of the ammonia synthesis reactor 11. In the embodiment of Fig.7 the ammonia purification module 13 is configured as a stand-alone module 13 having an ammonia inlet 13.1 and an ammonia outlet 13.2. The ammonia inlet 13.1 is fluidly coupled to an ammonia outlet 7.3 of the ammonia synthesis module 7. [0073] Unreacted nitrogen and hydrogen are removed by the ammonia purification module 13 from the gaseous ammonia-rich flow which enters the ammonia purification module 13. The unreacted gaseous species (N2, H2) are returned through a return line 15 to the mixing station 17, or directly to the syngas compression module 9, for further processing in the syngas compression sub-module 9 and in the ammonia synthesis reactor 11.

[0074] In the embodiment of Fig.7, the green ammonia production plant 1 further comprises an energy recovery system. In general terms, the energy recovery system may include devices for recovering thermal energy (heat), devices for recovering pressure energy, or a combination thereof, as further described in greater detail with reference to various embodiments.

[0075] In the embodiment of Fig.7, a generic energy recovery system is configured as an energy recovery sub-module labeled 31, which is included in the ammonia synthesis module 7. In this embodiment, the energy recovery sub-module 31 is positioned between the ammonia-rich gas outlet 11.2 of the ammonia synthesis reactor 11 and the ammonia outlet 7.3 of the ammonia synthesis module 7.

[0076] The ammonia-rich gas delivered by the ammonia synthesis reactor 11 is at a high temperature, for instance between 200°C and 600°C, preferably between 350°C and 550°C, for instance at around 400-500°C, and at high pressure, for instance between 50 bar and 250 bar, preferably between 70 bar and 180 bar, for instance at around 90-110 bar. Energy can thus be recovered therefrom in form of thermal energy through heat exchange, for instance using a heat recovery heat exchanger, with a hot side where the hot and pressurized ammonia-rich gaseous flow exchanges heat against a heat transfer fluid which flows in a cold side of the heat recovery heat exchanger. The heat transfer fluid can be used as a heating medium, to transfer heat to a user, or can be used to transfer heat in a thermodynamic cycle, for instance, wherein thermal energy is converted into mechanical energy by cyclic thermodynamic transformations of a working fluid which expands in an expander, such as a turbine, for instance a steam turbine. The working fluid can be the same heat transfer fluid, which circulates in the heat recovery heat exchanger, or a separate working fluid, receiving heat from the heat transfer fluid. [0077] The heat recovery heat exchanger may include, in this and other embodiments, one or more heat exchangers in sequence.

[0078] The working fluid can be vaporized in a steam generator.

[0079] In other embodiments, a steam generator can be used to exploit thermal power to generate steam which is then delivered to a user, different from a thermodynamic cycle.

[0080] Alternatively, or in combination, energy can be recovered in form of mechanical energy through direct expansion of the compressed gaseous ammonia-rich flow delivered by the ammonia synthesis reactor 11. Embodiments of energy recovery systems will be described in detail below. Energy recovered from ammonia outflowing from the ammonia synthesis reactor 11 can be used in one or more locations of the green ammonia production plant 1.

[0081] Any mechanical generating device, such as an expander or a turbine, included in the energy recovery system can directly supply mechanical power to a device of the ammonia production plant 1, for instance to one or more compressors of the syngas compression unit 9, or to other ancillary devices. Alternatively, or in combination, mechanical power generated by the energy recovery system 31 can be converted into electric energy by electric generator(s) drivingly coupled to one or more expanders or turbines of the energy recovery system 31.

[0082] In Fig.7 and in the following figures, reference Q and relevant dashed lines pictorially represent recovered energy transfer from the energy recovery system 31 towards several different sections of the green ammonia production plant 1.

[0083] A further embodiment of a green ammonia production plant 1 comprising an energy recovery system 31 is illustrated in Fig.8. The same reference numbers are used in Figs. 7 and 8 to designate the same or equivalent parts, elements, or components, which will not be described in detail again. The embodiment of Fig.8 differs from the embodiment of Fig.7 primarily in view of a different distribution of sub-modules. While in Fig.7 the green ammonia production plant 1 includes a syngas compression module 21 fluidly coupled to an ammonia synthesis module 7, in the embodiment of Fig.8 the apparatus for mixing hydrogen and nitrogen into a gas mixture (syngas) and for compressing the syngas are embedded in the ammonia synthesis module 7.

[0084] Specifically, in Fig.8 the ammonia synthesis module 7 includes in sequence: the mixing station 17, the syngas compression sub-module 9, the ammonia synthesis reactor 11 and the energy recovery system 31. This latter is again configured as an energy recovery sub-module contained in the ammonia synthesis module 7. The ammonia purification module is still configured as a stand-alone module 13.

[0085] With continuing reference to Figs. 7 and 8, a further distribution of the components of the green ammonia production plant 1 is shown in Fig.9. The same elements, parts and components already shown in Figs. 7 and 8 and described above are labeled with the same reference numbers and will not be described again in detail.

[0086] The embodiment of Fig.9 differs from the embodiments of Figs. 7 and 8 primarily in view of a different arrangement of the ammonia purification module. In the embodiment of Fig.9 the ammonia purification module 13 is not configured as a standalone module, but rather included as an ammonia purification sub-module in the ammonia synthesis module 7.

[0087] Additionally, the energy recovery system 31 of Fig.9 is pictorially represented as including two energy recovery units 31.1 and 31.2. The two energy recovery units can be configured to recover different forms of energy, for instance pressure energy through expansion and thermal energy through heat exchange. In some embodiments, the energy recovery unit 31.1 comprises an expander adapted to expand the ammonia- rich gas delivered from the ammonia synthesis reactor 11 and generate mechanical power therewith; and the energy recovery unit 31.2 comprises a heat exchanger, adapted to remove low-temperature heat from the expanded ammonia-rich gas. The recovered heat can be used as such, i.e., as thermal energy, or can be partly converted into mechanical energy through a thermodynamic cycle, for instance. As mentioned, the heat exchanger can in turn include a plurality of heat exchangers or heat exchanger sections in series.

[0088] In another embodiment, the energy recovery unit 31.1 comprises a heat exchanger to remove high-temperature heat from the ammonia-rich gas delivered from the ammonia synthesis reactor 11 and the energy recovery unit 31.2 comprises an expander adapted to recover mechanical energy by expansion of the ammonia-rich gas.

[0089] The same green ammonia production plant 1 of Fig.9, including a single-unit energy recovery system configured as a sub-module of the ammonia synthesis module 7 is shown in Fig.10, where the same reference numbers designate the same elements and components shown in Figs. 7, 8 and 9.

[0090] A further embodiment of a green ammonia production plant 1 according to the present disclosure is shown in Fig.11. The same reference numbers used in Figs. 1 to 10 are used to designate the same or equivalent components and elements of the embodiment shown in Fig.11.

[0091] The modular green ammonia plant 1 of Fig.11 comprises a nitrogen production module 3 having an air inlet 3.1 and a nitrogen outlet 3.2. The nitrogen production module 3 can include any known device or system adapted to separate nitrogen from air, i.e. any kind of air separation unit (ASU).

[0092] In some embodiments, the nitrogen production module 3 is powered by renewable energy (RE) as schematically shown at 3.3. The renewable energy can be generated by any renewable source of energy, such as solar or wind energy, hydropower, geothermal energy, or the like, which is suitably converted into electric energy or other forms of energy required by the nitrogen production module.

[0093] The green ammonia production plant 1 further comprises a hydrogen production module 5. The hydrogen production module 5 comprises a water inlet 5.1 and a hydrogen outlet 5.2 and can be powered by electric energy generated through a renewable energy source, and schematically shown at 5.3.

[0094] Nitrogen and hydrogen outflowing from the nitrogen production module 3 and the hydrogen production module 5 are mixed to form syngas which is compressed in a syngas compression sub-module 9, forming part of an ammonia synthesis module 7. In the embodiment of Fig.11, hydrogen and nitrogen are mixed in a mixing station 17, which also forms part of the ammonia synthesis module 7 and which has an outlet fluidly coupled to an inlet 9.1 of a syngas compression sub-module 9.

[0095] The ammonia synthesis module 7 is powered by energy from a renewable energy source, as shown at 7.4.

[0096] The ammonia synthesis module further comprises an ammonia synthesis reactor 11 fluidly coupled to a delivery side of the syngas compression sub-module 9. The syngas is compressed by the syngas compression sub-module 9 at a pressure adapted for conducting the ammonia synthesis reaction in the ammonia synthesis reactor 11, and is delivered to the ammonia synthesis reactor through an inlet 11.1 of the ammonia synthesis reactor 11.

[0097] The green ammonia production plant 1 of Fig.11 further comprises an ammonia purification module configured as a sub-module 13 having an ammonia inlet 13.1 and an ammonia outlet 13.2. The ammonia inlet 13.1 of the ammonia purification sub-module 13 is fluidly coupled with an ammonia-rich gas outlet 11.2 of the ammonia synthesis reactor 11 thorough an energy recovery system to be described.

[0098] Unreacted nitrogen and hydrogen are removed from the ammonia-rich gaseous flow through the ammonia purification module 13, and are returned through a return line 15 to the mixing station 17, or alternatively directly to the syngas compressor of the syngas compression sub-module 9, for further processing in the syngas compression sub-module 9 and in the ammonia synthesis reactor 11.

[0099] In the embodiment of Fig.11 the energy recovery system 31 includes a first energy recovery unit 31.1 and a second energy recovery unit 31.2. The first energy recovery unit of Fig.11 is a heat recovery unit and can be integrated in the ammonia synthesis reactor 11, i.e., can form part of the latter. The ammonia-rich gas obtained through reaction of the syngas in an ammonia synthesis reactor bed 11.5 flows through the first energy recovery unit 31.1 (heat exchanger) embedded in the ammonia synthesis reactor 11 before being delivered, through the ammonia-rich gas outlet 11.2, to the second energy recovery unit 31.2 and therefrom to the ammonia purification sub-module 13, wherefrom the purified ammonia is delivered an ammonia outlet 13.2 of the ammonia purification module 13 (corresponding to an ammonia outlet 7.3 of the ammonia synthesis module 7).

[0100] In the embodiment of Fig.11, the second energy recovery unit 31.2 is positioned between the ammonia synthesis reactor 11, and the ammonia purification sub- module 13. In the embodiment of Fig.11, the second energy recovery unit 31.2 is configured as a stand-alone module. In some embodiments, the second energy recovery unit 31.2 can include an expander, to directly expand the gaseous flow delivered by the ammonia synthesis reactor 11 and convert pressure energy contained in the ammonia-rich gaseous flow into mechanical power. Partly cooled ammonia-rich gaseous flow delivered from the ammonia synthesis reactor 11 through the first energy recovery unit 31.1 is thus expanded and further cooled in the expander of the second energy recovery unit 31.2. The cooled and depressurized ammonia-rich gaseous flow is treated in the ammonia purification sub-module 13 of the ammonia synthesis module 7 and finally delivered through the ammonia outlet 13.2.

[0101] Thus, in this embodiment the gaseous flow delivered by the ammonia synthesis reactor 11 flows outside the ammonia synthesis module 7, through the second energy recovery unit 31.2 and then re-enters the ammonia synthesis module 7 for further purification in the ammonia purification sub-module 13.

[0102] In the green ammonia production plant 1 of Fig.11 energy in form of thermal energy is extracted from the ammonia-rich gaseous flow in the first energy recovery unit 31.1 embedded in the ammonia synthesis reactor 11, prior to expanding the gaseous flow in the second energy recovery unit 31.2.

[0103] In other embodiments, the hot and pressurized ammonia-rich gaseous flow exiting the ammonia synthesis reactor 11 can be processed through an expander first, and next through a heat exchanger, to increase the amount of mechanical power generated by expansion of the gaseous flow and recover heat at a lower temperature.

[0104] With continuing reference to Fig.11, Fig.12 illustrates an embodiment including a pressure energy recovery unit 31.1 upstream of a thermal energy recovery unit 31.2 with respect to the direction of flow of the gas processed in the plant. The same reference numbers used in Figs. 11 and 12 designate the same or equivalent components, which will not be described in detail again.

[0105] One difference between the embodiment of Fig.11 and the embodiment of Fig.12 is that in the latter the energy recovery system is neither entirely nor partly embedded in the ammonia synthesis reactor 11. Rather, the entire energy recovery system is external to the ammonia synthesis reactor 11.

[0106] Another difference, as mentioned above, between Fig.11 and Fig.12, is that in Fig.12 the energy recovery system 31 includes a first energy recovery unit 31.1 adapted to recover pressure energy from the ammonia-rich gaseous flow released from the ammonia synthesis reactor 11, followed by a second energy recovery unit 31.2, adapted to recover heat, i.e. thermal energy from the expanded ammonia-rich gaseous flow discharged from the first energy recovery unit 31.1. In the embodiment of Fig.12, therefore, the first energy recovery unit 31.1 includes an expander and the second energy recovery unit 31.2 includes a heat exchanger.

[0107] In the embodiment of Fig.12, the first energy recovery unit 31.1 is configured as a stand-alone module, external to the ammonia synthesis module 7, while the second energy recovery unit 31.2 is configured as a sub-module of the ammonia synthesis module 7.

[0108] In the embodiment of Fig.12, the ammonia purification module 13 is configured as a sub-module of the ammonia synthesis module 7. In other embodiments, however, the ammonia purification module 13 can be configured as a stand-alone module, external to and separated from the ammonia synthesis module 7.

[0109] As can be understood from the description of the above-mentioned embodiments, energy from the gaseous flow exiting the ammonia synthesis reactor 11 can be recovered in form of mechanical energy generated by an expander, or in form of thermal energy, or both. Moreover, the thermal energy can be removed upstream or downstream of an expander, e.g., depending on the amount and temperature at which the thermal energy is more useful.

[0110] Additionally, in the various embodiments disclosed herein, the thermal energy removed from the ammonia-rich pressurized gaseous stream can be converted into mechanical energy in a thermodynamic circuit which can form part of the energy recovery system 31. For instance, a pressurized working fluid can exchange heat with the ammonia-rich gaseous flow from the ammonia synthesis reactor 11 and can be vaporized therewith. The vaporized, high-pressure working fluid can expand in a turbine generating mechanical power. The spent working fluid can be condensed and pressurized before entering the heat exchange of the energy recovery system 31 again. For example, the working fluid can be water. In other embodiments, the working fluid can be a different fluid, for instance an organic fluid of an organic Rankine cycle.

[OHl] A schematic of an energy recovery system 31 including a Rankine cycle powered with waste heat from the hot ammonia-rich gas, or gaseous flow, coming from the ammonia synthesis reactor 11 is depicted in Fig.20. Reference 34 indicates a heat recovery heat exchanger including a boiler. Hot ammonia-rich gas flows in the hot side of the heat exchanger 34 and a working fluid flow in the cold side of the heat exchanger 34 and is vaporized by heat transferred from the ammonia-rich gas which flows through the hot side of the heat exchanger 34. The vaporized and pressurized working fluid expands in an expander or turbine 36. Spent working fluid is condensed in a condenser 38 and pumped by a pump 40 back into the heat exchanger 34.

[0112] In the schematic of Fig.20, the mechanical power generator, represented by turbine 36, is drivingly coupled to an electric generator 42, which converts mechanical power into electric power. The thermodynamic circuit schematically shown in Fig.20 can be included in any one of the energy recovery systems 31 described herein, to recover heat from the ammonia-rich gas streaming from the ammonia synthesis reactor 11 and convert at least part of the recovered heat into mechanical and/or electric power. Additional, low temperature heat can be collected at the condenser 38 of the thermodynamic circuit.

[0113] It shall be understood that the thermodynamic circuit schematically represented in Fig.20 is only by way of non-limiting example, and that more complex or different thermodynamic circuits can be used to convert heat into useful mechanical and/or electric power.

[0114] Heat can be transferred to the thermodynamic circuit indirectly, instead of directly. In this case, a heat transfer loop with a heat transfer fluid circulating therein can be positioned between the heat recovery heat exchanger of the energy recovery system 31 and a boiler of a Rankine cycle, for example. This may be particularly beneficial in case of an organic Rankine cycle is used.

[0115] In Figs 9, 11 and 12, energy recovery is performed in two steps. In other embodiments, energy recovery can be split in more than two steps, e.g., to recover thermal energy at different temperature levels in combination with mechanical energy recovery by direct expansion of the ammonia-rich gaseous flow delivered by the ammonia synthesis reactor 11.

[0116] With continuing reference to Fig.12, Fig.13 shows an embodiment which enables thermal energy recovery at different temperature levels and intermediate recovery of pressure energy in the form of mechanical energy. The same reference numbers in Figs. 12 and 13 designate the same or equivalent components or parts of the green ammonia production plant 1. These parts or components will not be described in detail again.

[0117] In Fig.13 the energy recovery system, again labeled 31, comprises a first energy recovery unit 31.1 and a second energy recovery unit 31.2. The first energy recovery unit 31.1 is in turn split into a first sub-unit 31.11 and a second sub-unit 31.12. Each sub-unit 31.11 and 31.12 can include a heat exchanger, wherein heat from the ammonia-rich flow exiting the ammonia synthesis reactor 11 is removed by heat exchange against a heat transfer fluid, for instance, or a working fluid circulating in a thermodynamic circuit. The second energy recovery unit 31.2 can include an expander, wherein partly cooled ammonia-rich gaseous flow exiting the sub-unit 31.11 is expanded for direct conversion of pressure energy into mechanical energy prior to further cooling of the ammonia-rich flow in the second sub-unit 31.12.

[0118] In the embodiment of Fig.13, the first sub-unit 31.11 of the first energy recovery unit 31.1 is embedded in the ammonia synthesis reactor 11. In other embodiments, the first sub-unit 31.11 of the first energy recovery unit 31.1 can be configured as a sub-unit of the ammonia synthesis module 7, separate from, and downstream of the ammonia synthesis reactor 11.

[0119] In the embodiment of Fig.13, the second energy recovery unit 31.2, comprising or consisting of an expander, is configured as a stand-alone module, external to the ammonia synthesis module 7 and connected thereto by an outlet of the ammonia synthesis module 7. The delivery side of the expander can be fluidly coupled to a further inlet of the ammonia synthesis module 7 and specifically with the second sub-unit 31.12, which is configured as a sub-module of the ammonia synthesis module 7. [0120] In the embodiment of Fig.13, the second sub-unit 31.12 of the energy recovery system 31 comprises an outlet, which is fluidly coupled with an inlet of the ammonia purification module 13. In Fig.13 the ammonia purification module 13 is configured as a sub-module of the ammonia synthesis module 7, but could be configured as a stand-alone module, as shown in Figs 7 or 8, for instance.

[0121] A modular, green ammonia production plant 1 with a different distribution of the various modules and sub-modules is shown in Fig.14. The same reference numbers are used to designate the same or similar component, parts and elements, described above in connection with Figs. 1 to 13.

[0122] In the embodiment of Fig.14, the modular green ammonia plant 1 comprises a nitrogen production module 3 having an air inlet 3.1 and a nitrogen outlet 3.2. The nitrogen production module 3 can include any known device or system adapted to separate nitrogen from air, i.e., any kind of air separation unit (ASU). The nitrogen production module 3 is powered by renewable energy (RE) as schematically shown at 3.3.

[0123] The green ammonia production plant 1 of Fig.14 further comprises a hydrogen production module 5, which in turn comprises a water inlet 5.1 and a hydrogen outlet 5.2 and can be powered by electric energy generated through a renewable energy source, and schematically shown at 5.3.

[0124] The nitrogen outlet 3.2 and the hydrogen outlet 5.2 are fluidly coupled to respective nitrogen inlet and hydrogen inlet of a mixing station 17. Alternatively, the nitrogen outlet and hydrogen outlet can be directly coupled to a suction side of a syngas compressor of a syngas compression sub-module 9.

[0125] In the embodiment of Fig.14, the mixing station 17 is installed as a functional component on a syngas compression module 21. Similarly to the other modules of the plant 1, the syngas compression module 21 can be powered by renewable energy RE as shown at 21.1.

[0126] In this embodiment, the syngas compression module 21 comprises the mixing station 17 and a syngas compression sub-module, again labeled 9. The syngas compression sub-module 9 comprises a syngas inlet 9.1 and a syngas outlet 9.2, which is in turn fluidly coupled to an outlet 21.2 of the syngas compression module 21. One or more syngas compressors are included in the syngas compression module 21.

[0127] The outlet 21.2 of the syngas compression module 21 is fluidly coupled to an inlet 7.5 of an ammonia synthesis module 7, which can be powered with renewable energy (RE), see 7.4. In this embodiment, the ammonia synthesis module 7 comprises an ammonia synthesis reactor 11 and an ammonia purification sub-module 13, having an ammonia inlet 13.1 and an ammonia outlet 13.2. A return line 15 fluidly couples an unreacted gases outlet of the ammonia purification module 13 with an upstream section, in the embodiment of Fig.5 with the mixing station 17. Alternatively, the return line 15 could be fluidly connected to the syngas compression module 9 directly, e.g. with a suction side of the syngas compressor of the syngas compression module 9. The outlet of the ammonia purification module 13 coincides with the ammonia outlet 7.3 of the ammonia synthesis module 7.

[0128] The green ammonia production plant 1 of Fig.14 includes an energy recovery system, again labeled 31. The energy recovery system 31 can be configured in any one of the manners described above. In the schematic of Fig.14, the energy recovery system 31 comprises a first energy recovery unit 31.1 and a second energy recovery unit 31.2.

[0129] In some embodiments, the first energy recovery unit 31.1 can include a heat exchanger to recover thermal energy and the second energy recovery unit 31.2 can include an expander, to convert pressure energy of the compressed ammonia-rich gaseous flow in mechanical energy. This latter can be used to operate the syngas compressors) in the syngas compression sub-module 9.

[0130] A reverse arrangement can be provided, with a pressure energy recovery unit arranged upstream (first energy recovery unit 31.1) and a thermal energy recovery unit arranged downstream (second energy recovery unit 31.2). In some embodiments, since high-temperature compressed gas provides a higher efficiency of the expander, the pressure energy recovery unit is arranged at 31.1, i.e., in the upstream position. If the thermal energy recovery sub-unit is the first unit 31.1, heat recovered therefrom can be used to heat the feedstock, if needed.

[0131] In some embodiments, as shown in Fig.14, the first energy recovery unit 31.1 is configured as a sub-module of the syngas compression module 21 and the second energy recovery unit 31.2 is configured as a sub-unit of the ammonia synthesis module 7.

[0132] As mentioned above the thermal energy recovery unit can in turn include a thermodynamic cycle, which converts thermal energy into mechanical energy.

[0133] A further embodiment of a green ammonia production plant 1 is shown in Fig.15. In this embodiment, the green ammonia production plant 1 comprises a nitrogen production module 3, a hydrogen production module 5 and an ammonia synthesis module 7. This latter includes a mixing station 17, a syngas compression module 9 and an ammonia synthesis reactor 11. An energy recovery system is configured as a standalone energy recovery module 31. In this embodiment, the energy recovery module 31 includes a first energy recovery unit 31.1 and a second energy recovery unit 31.2. The two energy recovery units 31.1 and 31.2 can be configured as described above in connection with one or more of the previously described embodiments. Hot ammonia-rich pressurized stream from the ammonia synthesis reactor 11 is processed through the energy recovery units 31.1 and 31.2 to extract energy therefrom, either in form of thermal energy or in form of pressure energy, or both. The ammonia-rich gaseous flow is then processed in an ammonia purification module 13, which in this embodiment is configured as a stand-alone module, fluidly coupled on one side with the energy recovery module 31 and on the other side with an ammonia delivery outlet 13.2. A return line 15 conveys unreacted hydrogen and nitrogen from the ammonia purification unit 13 back to the ammonia synthesis module 7, for instance to the mixing unit 17, as shown, or to the syngas compression module 9.

[0134] With continuing reference to Fig.15, a further embodiment of a green ammonia production plant 1 is shown in Fig.16, wherein the same reference numbers used in Fig.15 designate the same or equivalent parts, elements or components, which will not be described again. The main difference between Figs. 15 and 16 relates to the position of the ammonia purification module 13, which in Fig.16 is configured as a sub-module of the ammonia synthesis module 7. The energy recovery system 31 is configured as a stand-alone module, or is embedded in a stand-alone module, which can include further devices and instrumentalities, as described below. The energy recovery system 31 comprises an inlet fluidly coupled with the ammonia-rich gas outlet 11.2 of the ammonia synthesis reactor 11, and an outlet fluidly coupled with an inlet of the ammonia synthesis module 7 and more specifically with the inlet 13.1 of the ammonia purification module 13.

[0135] Moreover, in Fig.16 a configuration is shown, wherein the stand-alone module containing the energy recovery system 31 also contains an energy managing and control sub-module, which receives power at 31.6 from a renewable energy source. The energy managing sub-module distributes from module 31 the required energy to the remaining modules of the system, e.g., the nitrogen generation module 3, the hydrogen generation module 5 and the ammonia synthesis module 7.

[0136] The same approach can be used also in other embodiments disclosed herein, including a stand-alone module containing the energy recovery system or part thereof.

[0137] Each of the above-described embodiments can be further implemented by a system for using oxygen produced by the nitrogen production module 3 and/or the hydrogen production module 5.

[0138] For instance, oxygen produced by the nitrogen production module 3 and/or by the hydrogen production module 5 can be delivered to a user, which may be configured as a further module of the green ammonia production plant 1. Fig.17 illustrates the same plant 1 of Fig.15, with the addition of a user facility module 41, fluidly coupled with the nitrogen production module 3 and with the hydrogen production module 5 to receive oxygen therefrom. It shall be understood that a similar user facility module 41 can be included in any one of the green ammonia production plants 1 illustrated in the previously described embodiments.

[0139] By way of example, in Fig.17 power from a renewable energy source (RE) is delivered at 31.6 to the energy recovery module 31, and distributed therefrom to the remaining parts of the plant, in the same way as described in connection with Fig.16.

[0140] In further embodiments, excess hydrogen produced by the hydrogen production module 5 can be used as a fuel in a power generation module 43, which can be combined with, or form part of the green ammonia production plant 1. An embodiment including a power generation module 43 is shown in Fig.18, wherein the structure of the remaining part of the plant 1 is the same as in Fig.17. It shall be understood, however, that a similar power generation module 43 can be used also in any other embodiment of the green ammonia production plant 1 described herein.

[0141] In some embodiments, the green ammonia production plant 1 can include a hydrogen storage tank 2. By way of example, a hydrogen storage tank 2 is show in Fig.18. The hydrogen storage tank 2 can be fluidly coupled at 4 with the hydrogen outlet 5.2 of the hydrogen production module 5. The hydrogen production module 5 is powered with energy from a renewable energy source.

[0142] In general, the storage tank 2 can be configured as a small buffer tank, to avoid storing large amounts of hydrogen. The buffer tank can be provided each time this is needed for plant integration and functionality purposes, e.g. to keep the output pressure stable and manage the ramping-up and ramping-down transients.

[0143] The power available from a renewable energy source can be inherently fluctuating. Consider, for example, a solar energy system, where the output power is zero during nighttime hours and can vary significantly during daylight hours depending on irradiance conditions, and therefore, depending on seasons and weather conditions. In view of the fluctuating nature of the energy resource, it might be useful or necessary to store energy produced in excess during certain period of the day and use it at startup or during periods where less power or no power is available from the renewable energy source. Energy can be best stored in form of chemical energy by storing in the storage tank 2 hydrogen generated by electrolysis when the renewable energy source delivers high power The stored energy in the form of hydrogen contained in storage or buffer tank 2 can be utilized, for example, when starting up a plant 1 powered by solar energy.

[0144] Flexibility of the modular plant disclosed herein can also be targeted by selecting a component design allowing intermittency that is inherent in the use of energy from renewable energy sources.

[0145] The power generation module 43 can include an internal combustion engine, for instance a reciprocating engine, or a gas turbine engine, fueled with hydrogen from the hydrogen production module 5. Oxygen from the nitrogen production module 3 can be also used in the power generation module 43 as oxidant, alone or in combination with air, for instance.

[0146] In other embodiments the power generation module 43 can include fuel cells fueled with hydrogen from the hydrogen production module 5, or from the storage tank 2, and oxygen from the nitrogen production module 3.

[0147] In yet further embodiments, the power generation module 43 can include a combination of different power generation units, such as one or more internal combustion engine (including gas turbine engines) and fuel cells.

[0148] An oxygen storage tank 8 can be also fluidly coupled to the hydrogen production module 5, to store oxygen therein. Alternatively, or in combination, the nitrogen production module 3 can also be fluidly coupled with an oxygen storage tank 6, as shown by way of example in Fig.18, such that oxygen produced in excess by the oxygen production module 3 can be stored therein.

[0149] In Fig.18 the power generation module 43 is combined with a user facility module 41. In other embodiments, oxygen produced by the oxygen production module 3 can be used in a power generation module 43 without being delivered to a different user facility module.

[0150] The power generated by power generation module 43 can be mechanical power or electric power for instance, and can be supplied to one or more of the remaining modules of the green ammonia production plant 1 as pictorially shown in Fig.18. One or more of said modules of the green ammonia production plant 1 can therefore be powered entirely by power from the power generation module 43, or by power from the renewable energy source (not shown), for instance at start-up or during transients, when insufficient power is available from the renewable energy source.

[0151] While in the above-described embodiments the power generation module 43 is powered with hydrogen from the hydrogen production module 5, either directly fed to the power generation module 43 or intermediately stored in the storage tank 2, in other embodiments, hydrogen and possibly ammonia can be delivered as fuel to the power generation module 43 from the return line 15. Fueling hydrogen and/or ammonia from the return line 15 can be used alone or in combination with hydrogen from the hydrogen production module 5 and/or the storage tank 2 combined therewith.

[0152] In general terms, in several embodiments of the green ammonia production plant 1 disclosed above three main modules are present, namely: a nitrogen production module 3 adapted to separate nitrogen from air, for instance by a cryogenic process, a membrane process, or any other suitable separation process; a hydrogen production module 5 adapted to produce hydrogen from water (either in liquid form or in form of steam) through electrolysis and including an electrolyser; and an ammonia synthesis module 7 including at least an ammonia synthesis sub-module 11.

[0153] Various arrangements of the other functional blocks of the plant have been disclosed above, the functional blocks including: a mixing station; a compression module or sub-module, including a syngas compressor; an energy recovery system including one or more units, adapted to recover thermal energy or pressure energy; an ammonia purification module or sub-module; a power generation module, including devices to generate power from hydrogen provided by the hydrogen production module.

[0154] The hydrogen production module and the nitrogen production module represent the so-called front-end of the plant. The front end is connected to the ammonia synthesis loop, referred to also as the back-end of the plant, which consists in one or more separate plug&play modules embedding the ammonia synthesis reactor 11, the syngas compression module or sub-module, and the ammonia purification module or sub-module, which separates ammonia from unreacted nitrogen and hydrogen, which are recycled to the compressor.

[0155] The configuration is modular also in terms of size, since some at least of the modules may include one or more sub-modules in parallel to perform the same function. Specifically, in some embodiments, the nitrogen production module 3 can include a plurality of nitrogen production sub-modules in parallel. In some embodiments, the hydrogen production module 5 can include a plurality of hydrogen production submodules in parallel. Similarly, in some embodiments, the ammonia synthesis module can include a plurality of ammonia synthesis reactors in parallel.

[0156] The number of hydrogen production sub-modules, the number of nitrogen production sub-modules, and/or the number of ammonia synthesis reactors can depend upon the required nitrogen, hydrogen and ammonia flowrates. This modularity allows to adapt the size of the plant to specific requirements, without the need to re-design the entire plant.

[0157] Fig.19 illustrates a schematic green ammonia production plant 1 according to the present disclosure, including multiple nitrogen and hydrogen production sub-modules as well as a plurality of ammonia synthesis reactors.

[0158] More specifically, the green ammonia production plant 1 of Fig.19 comprises a nitrogen production module 3, including a nitrogen outlet 3.2 and an air inlet 3.1, as described above. The nitrogen production module 3 can include two or more nitrogen production sub-modules 3A, 3B arranged in parallel. The plant 1 further comprises a hydrogen production module 5, including a hydrogen outlet 5.2 and a water inlet 5. The nitrogen production module 5 can include two or more hydrogen production submodules 5 A, 5B.

[0159] In the embodiment of Fig.19, the plant 1 further includes an ammonia synthesis module 7, which in this embodiment includes a syngas compressor sub-module 9, having an inlet 9.1 fluidly coupled to a mixing station 17 and an outlet 9.2 fluidly coupled to an ammonia synthesis reactor system 11. The latter includes two or more ammonia synthesis reactors 11 A, 11B in parallel, having inlet 11.1 fluidly coupled to the outlet 9.2 of the syngas compressor sub-module 9. Reference 13 includes an ammonia purification sub-module, which may include an ammonia liquefaction system and which may be fluidly coupled to the syngas compression sub-module 9 by a return line, not shown.

[0160] The ammonia synthesis reactor system 11 is functionally coupled to an energy recovery unit 31, which can include a thermal management system, adapted to recover thermal energy from the compressed and hot ammonia-rich gaseous stream delivered by the ammonia synthesis reactor system 11.

[0161] As mentioned above, the energy recovery system 31 can also include an expander or other pressure energy recovery arrangement to recover energy from the pressurized flow exiting the ammonia synthesis reactors 11 A, 1 IB.

[0162] The energy recovery system 31 can be functionally coupled to any one of the modules and/or sub-modules of the plant 1. In the schematic of Fig.19 the energy recovery system 31 is connected (line 51) with the hydrogen production module 5 and with a user 41 (line 53). This latter can also be fluidly couple to the nitrogen production module 3 and/or with the hydrogen production module 5 to receive oxygen therefrom. In some embodiments, the energy recovery system 31 can also be functionally coupled to the syngas compression sub-module 9 as pictorially represented by dashed line 53, for instance to recover compression heat therefrom.

[0163] In other embodiments, the syngas compression module 9 can in turn include one or more sub-modules or units in parallel, which can be configured as a modular structure, quite in the same way as the hydrogen production sub-modules 5 A, 5B and the nitrogen production sub-modules 3A, 3B. Thus, the syngas compression module 9 may be split in two or more sub-modules in parallel, each including at least one syngas compressor.

[0164] Generally speaking, the nitrogen production module 3, the hydrogen production module 5 and the syngas compression module 9 can (each independently form the others) be comprised of a plurality of sub-modules, depending upon needs of the plant. The sub-modules can be arranged in parallel or in series. In particular, the nitrogen productions sub-modules, the hydrogen production sub-modules and the ammonia synthesis reactor sub-modules will usually be arranged in parallel and the number of sub-modules can vary depending upon needs, e.g. based on the required flowrate, or on the degree of reliability required. The syngas compression sub-modules will usually be arranged in parallel and/or in series, to cope with needs of the plant, e.g., in terms of flowrate, compression ratio, reliability of the plant. In some embodiments, each syngas compression sub-module may include compressors or compressor stages arranged in series to achieve the required pressure ratio, and several sub-modules can be arranged in parallel to achieve the required flowrate.

[0165] As mentioned, the possibility of using multiple sub-modules 3 A, 3B, 5A, 5B, 11 A, 11B and multiple syngas compression sub-modules increases the flexibility in terms of plant design, since a different number of sub-modules can be used, depending for instance on the required flowrates. Additionally, splitting each service (H2 production, N2 production, compression, and ammonia synthesis reaction) in sub-modules offers the possibility to increase the reliability of the plant, since whenever one submodules of a cluster of multiple sub-modules becomes inoperative for whatever reason, the other(s) surviving sub-modules allow continuation of the plant operation.

[0166] In the above description of various embodiments of the green ammonia plant according to the present disclosure, reference is made to multiple modules combined together. As noted at the outset of the present disclosure, one, some, or each such module may be configured as a skid or a combination of skids. Each skid can comprise a base plate and the relevant equipment mounted thereon. The required connections between functionally coupled modules can be provided in the form of plug-in couplings. A plug-in connector architecture can be used for any type of connection or coupling between functionally coupled modules. Thus, a plug-in coupling can be used for any mechanical or fluid coupling. Plug couplings can also be used to electrically connect modules to each other for both data and power transmission.

[0167] A modular architecture as described herein, possibly comprised of skids and plug-in couplings therebetween, allows a fast installation of the plant, as each module or skid can be tested in advance, for instance at the site of manufacturing, and does not require any further testing in the site where the plant is erected. Plug-in couplings enable fast connection between modules or skids, reducing the time needed for plant erection, as well as for dismantling.

[0168] In addition, the plant layout can be easily modified as needed, for example, to increase or decrease plant capacity. Standard skids, which form standard modules, can be designed and manufactured separately. A complete plant can then be configured by assembling the required or desired types and numbers of different skids.

[0169] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various changes, omissions and additions may be made to that which is specifically disclosed herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A modular green ammonia plant, comprising:

- a nitrogen production module having an air inlet and a nitrogen outlet;

- a hydrogen production module having a water inlet and a hydrogen outlet; and

- an ammonia synthesis module comprising:

• a common inlet adapted to receive a mixture of nitrogen and hydrogen, or separate hydrogen inlet and nitrogen inlet; said inlets adapted to be fluidly coupled with the nitrogen outlet and with the hydrogen outlet

• an ammonia synthesis reactor having an inlet adapted to receive pressurized syngas containing nitrogen and hydrogen, and an ammonia outlet.

2. The modular green ammonia plant of claim 1, further comprising a syngas compression module; wherein the syngas compression module is adapted to be fluidly coupled to the inlet of the ammonia synthesis reactor; and wherein the syngas compression module further comprises a nitrogen inlet adapted to be fluidly coupled to the nitrogen outlet of the nitrogen production module, and a hydrogen inlet adapted to be fluidly coupled to the hydrogen outlet of the hydrogen production module.

3. The modular green ammonia plant of claim 1, further comprising a syngas compression module; wherein the syngas compression module is adapted to be fluidly coupled to the inlet of the ammonia synthesis reactor; and wherein the syngas compression module further comprises a common inlet adapted to be fluidly coupled to an outlet of a mixing station, the mixing station having a first inlet adapted to be fluidly coupled to the nitrogen outlet of the nitrogen production module and a second inlet adapted to be fluidly coupled to the hydrogen outlet of the hydrogen production module.

4. The modular green ammonia plant of claim 3, wherein the mixing station is configured as a mixing station sub-module of the ammonia synthesis module and the compression module is configured as a compression sub-module of the ammonia synthesis module.

5. The modular green ammonia plant of claim 3, wherein the mixing station is configured as a mixing station sub-module of a compression module; and wherein the syngas compression module is configured as a syngas compression submodule of the compression module.

6. The modular green ammonia plant of any one of the preceding claims, further comprising an ammonia purification module adapted to be fluidly coupled to the ammonia-rich gas outlet of the ammonia synthesis reactor.

7. The modular green ammonia plant of claim 6, wherein the ammonia purification module is configured as an ammonia purification sub-module of the ammonia synthesis module.

8. The modular green ammonia plant of claim 6 or 7, wherein the ammonia purification module is fluidly coupled with a return line adapted to receive unreacted hydrogen and nitrogen from the ammonia purification module; and wherein the return line is adapted to recycle the unreacted components upstream of the ammonia synthesis reactor.

9. The modular green ammonia plant of any one of the preceding claims, further comprising an energy recovery system.

10. The modular green ammonia plant of claim 9, wherein the energy recovery system is configured as a sub-module of the ammonia synthesis module.

11. The modular green ammonia plant of claim 9, wherein the energy recovery system is at least partly arranged in an energy recovery module separate from the ammonia synthesis module.

12. The modular green ammonia plant of claim 9, wherein the energy recovery system comprises at least a first energy recovery unit and a second energy recovery unit, and wherein the first energy recovery unit is configured as a sub-module of the ammonia synthesis module and the second energy recovery unit is external to the ammonia synthesis module.

13. The modular green ammonia plant of claim 12, when dependent at least upon claim 2, wherein the second energy recovery unit is configured as a sub- module of the syngas compression module.

14. The modular green ammonia plant of any one of claims 9 to 13, wherein the energy recovery system comprises a heat recovery heat exchanger.

15. The modular green ammonia plant of claim 14, wherein the heat recovery heat exchanger is adapted to transfer heat to a working fluid of a thermodynamic circuit of the energy recovery system; and wherein the thermodynamic circuit comprises a mechanical power generation turbomachine adapted to expand the working fluid and produce mechanical power therefrom.

16. The modular green ammonia plant of any one of claims 9 to 15, wherein the energy recovery system comprises an expander adapted to receive and expand therein a flow of ammonia-rich gas from the ammonia synthesis reactor and produce mechanical power therewith.

17. The modular green ammonia plant of claim 16, when depending upon at least claim 15, wherein the heat recovery heat exchanger is positioned between the ammonia synthesis reactor and the expander, such that ammonia-rich gas from the ammonia synthesis reactor flows in sequence through the heat recovery heat exchanger and the expander.

18. The modular green ammonia plant of claim 16, when depending upon at least claim 14, wherein the expander is positioned between the ammonia synthesis reactor and a heat recovery heat exchanger, such that ammonia-rich gas from the ammonia synthesis reactor flows in sequence through the expander and the heat recovery heat exchanger.

19. The modular green ammonia plant of claim 16, when depending upon at least claim 14, wherein the heat recovery heat exchanger comprising a first heat exchanger section positioned between the ammonia synthesis reactor and the expander and a second heat exchanger section positioned downstream of the expander such that ammonia-rich gas from the ammonia synthesis reactor flows in sequence through the first heat exchanger section, the expander and the second heat exchanger section.

20. The modular green ammonia plant of any one of claims 14 to 19, wherein the heat recovery heat exchanger is at least partly integrated with the ammonia synthesis reactor.

21. The modular green ammonia plant of any one of claims 9 to 20, wherein the energy recovery system is positioned in an energy management module or in an energy management and control module.

22. The modular green ammonia plant of any one of claims 9 to 21, wherein energy recovered by the energy recovery system is delivered to at least one of the following: the ammonia synthesis module; the hydrogen production module; the nitrogen production module.

23. The modular green ammonia plant of any one of claims 9 to 22, when dependent upon at least claim 6, wherein energy recovered by the energy recovery system is delivered to the syngas compression module.

24. The modular green ammonia plant of any one of claims 9 to 23, when dependent upon at least claim 2, wherein energy recovered by the energy recovery system is delivered to the ammonia purification module.

25. The modular green ammonia plant of any one of the preceding claims, further comprising a power generation module adapted to receive hydrogen from the hydrogen production module and generate power therefrom.

26. The modular green ammonia plant of claim 25, wherein the power generation module is adapted to receive oxygen from at least one of the nitrogen production module and the hydrogen production module.

27. The modular green ammonia plant of claim 25 or 26, when depending at least upon claim 6, wherein the power generation module is adapted to receive hydrogen, or ammonia or a combination of hydrogen and ammonia from the ammonia purification module.

28. The modular green ammonia plant of any one of the preceding claims, further comprising a user facility adapted to receive oxygen from at least one of the nitrogen production module and the hydrogen production module.

29. The modular green ammonia plant of any one of the preceding claims, wherein the nitrogen production module comprises a plurality of nitrogen production sub-modules.

30. The modular green ammonia plant of any one of the preceding claims, wherein the hydrogen production module comprises a plurality of hydrogen production sub-modules.

31. The modular green ammonia plant of any one of the preceding claims, wherein ammonia synthesis module comprises a plurality of ammonia synthesis reactors.

32. The modular green ammonia plant of any one of the preceding claims, wherein the syngas compression module comprises a plurality of syngas compression sub-modules.

33. The modular green ammonia plant of any one of the preceding claims, wherein at least one module of the plant comprises a base plate and relevant equipment installed thereon.

34. The modular green ammonia plant of any one of the preceding claims, wherein at least one fluid or power coupling between functionally connected modules is a plug-in coupling.