Novel compression train arrangements for ammonia synthesis systems

Abstract

The ammonia production system comprises a hydrogen source and a hydrogen compression unit, configured to compress hydrogen from the hydrogen source. The system further comprises a nitrogen source and a syngas compressor, configured to receive nitrogen from the nitrogen source and hydrogen from the hydrogen compression unit, and further configured to compress a syngas including a mixture of hydrogen and nitrogen and deliver the compressed gas mixture to an ammonia synthesis module. The hydrogen source and the nitrogen source are fluidly coupled to the syngas compressor. The hydrogen compression unit is configured to deliver hydrogen at pressures of 8 to 17 bar.

Description

71PRO-511194-WO-2_ BHI0598PCTNOVEL COMPRESSION TRAIN ARRANGEMENTS FOR AMMONIA SYNTHESIS SYSTEMSCROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of an earlier filing date from Italian Application Serial No. 102024000026604, filed November 26, 2024, the entire disclosure of which is incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to ammonia synthesis plants and methods. Specifically, disclosed herein are novel compression train arrangements for ammonia synthesis systems and relevant methods.BACKGROUND ART

[0003] Ammonia (NH3) is a gas with a high solubility in water, which is often used in an aqueous solution. Ammonia is used in several industrial applications, among others for the production of nitric acid, urea and other ammonia salts, such as nitrates, phosphates, and the like. Ammonia derivatives are widely used in agriculture. Around 80% of the ammonia production is used for the manufacturing of fertilizers.

[0004] Ammonia production usually starts from a feed gas, which provides a source of hydrogen, such as methane, for instance. Nitrogen is obtained from air.

[0005] Alternative methods for ammonia synthesis use hydrogen obtained by electrolysis. Recently, in an attempt to reduce production of greenhouse gases and avoid use of hydrocarbons, so-called green ammonia production processes and systems have been intensively investigated. Green ammonia production is where the process of making ammonia is 100% renewable and carbon-free. One way of making green ammonia is by using nitrogen separated from air and hydrogen from water electrolysis powered by renewable energy resources. Nitrogen and hydrogen are then fed into a Haber process (also known as Haber- Bosch process), where hydrogen and nitrogen are reacted together at high temperatures and pressures to produce ammonia.71PRO-511194-WO-2_ BHI0598PCT

[0006] Irrespective of the synthesis process used, one aspect of ammonia production using hydrogen produced by electrolysis at ambient pressure is the need for compressing the hydrogen at the high pressures used for the synthesis reaction.

[0007] Compressing gas having a low molecular weight (Mw) may be challenging, as the lower the molecular weight of the gas, the higher the rotational speed of the compressor impellers and / or the number of compressor stages and compressor casings needed to achieve the desired compression ratio. Long compressor trains including a large number of compressor stages possibly divided into several compressor casings pose challenging problems to the designers in terms of rotor-dynamic issues, among others.

[0008] The need to compress hydrogen from ambient pressure, at which it is produced by electrolysis, up to the pressures needed for an efficient ammonia synthesis reaction makes the design of hydrogen compressors particularly demanding, both in terms of number of compressor stages, as well as in terms of rotational speed thereof, when dynamic compressors, such as centrifugal compressors, are used.

[0009] It would therefore be beneficial to simplify the structure, manufacture and control of hydrogen compressors in an ammonia production system, specifically in a green ammonia synthesis system.SUMMARY

[0010] According to one aspect, disclosed herein is an ammonia production system, which includes a hydrogen source and a hydrogen compression unit, configured to compress hydrogen from the hydrogen source. The system further includes a nitrogen source. A syngas compressor is located downstream to receive nitrogen from the nitrogen source and hydrogen from the hydrogen compression unit, and further configured to compress a syngas including a mixture of hydrogen and nitrogen for delivery to an ammonia synthesis module, fluidly coupled to the syngas compressor. The hydrogen compression unit compresses hydrogen up to at most 15 bar, and up to 10 bar.

[0011] The hydrogen compression unit includes at least one dynamic compressor, for instance, a centrifugal compressor. In embodiments, the hydrogen compression unit includes a plurality of dynamic compressors in series to achieve the desired compression ratio.71PRO-511194-WO-2_ BHI0598PCT

[0012] As defined herein, ammonia synthesis gas, often referred to as syngas, is a mixture of gases that serves as the primary feedstock for the production of ammonia in the Haber-Bosch process. The composition of this gas is carefully controlled to optimize the ammonia synthesis reaction, which combines nitrogen (N ) and hydrogen (H ) to form ammonia (NH3).

[0013] In another aspect, disclosed herein is an ammonia production system, which includes a hydrogen source. The system further includes a nitrogen source and a nitrogen turboexpander unit, configured to expand nitrogen from the nitrogen source. A syngas compressor (located downstream of the nitrogen turboexpander) receives nitrogen from the nitrogen turboexpander unit and hydrogen from the hydrogen source. The syngas compressor is configured to compress a syngas including a mixture of hydrogen and nitrogen for delivery to an ammonia synthesis module.

[0014] The nitrogen turboexpander unit includes at least one dynamic turboexpander. In embodiments, the nitrogen turboexpander unit converts the energy generated into other usable forms of energy such as electrical energy.

[0015] According to a further aspect, a method for producing ammonia from hydrogen and nitrogen is disclosed. The method comprises delivering a nitrogen flow, at a syngas suction pressure, to a suction side of a syngas compressor. The method further includes the step of delivering a hydrogen flow at a hydrogen inlet pressure, lower than the syngas suction pressure, to a suction side of a hydrogen compression unit. A further step includes boosting the pressure of the hydrogen flow from the hydrogen inlet pressure to the syngas suction pressure in the hydrogen compression unit and delivering the compressed hydrogen to the syngas compressor. The syngas suction pressure is at most 15 bar, and up tolO bar. Additionally, the method also includes the step of delivering pressurized syngas from the syngas compressor to an ammonia synthesis module and producing ammonia from the compressed syngas.

[0016] According to a further aspect, a method for producing ammonia from hydrogen and nitrogen is disclosed. The method comprises delivering a hydrogen flow, at a syngas suction pressure, to a suction side of a syngas compressor. The method further includes the step of delivering a nitrogen flow at a nitrogen inlet pressure, lower than the syngas suction pressure, to a suction side of a nitrogen turboexpander unit. A further step includes reducing the pressure of the nitrogen flow from the nitrogen inlet pressure to the syngas suction pressure71PRO-511194-WO-2_ BHI0598PCT in the nitrogen turboexpander unit and delivering the expanded nitrogen to the syngas compressor. The syngas suction pressure is 1 bar to 5 bar. Additionally, the method also includes the step of delivering pressurized syngas from the syngas compressor to an ammonia synthesis module and producing ammonia from the compressed syngas.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Reference is now made briefly to the accompanying drawings, in which:

[0018] FIG. 1 is a schematic of an exemplary ammonia production system;

[0019] FIG. 2 is a flowchart summarizing a method according to the present disclosure,

[0020] FIG. 3 is a schematic of another embodiment of the ammonia production system; and

[0021] FIG. 4 is a flowchart summarizing an alternate method of the present disclosure.DETAILED DESCRIPTION

[0022] In general terms, disclosed herein is a system for ammonia synthesis, including novel features configured to simplify the structure or the design of the hydrogen compression unit.

[0023] The system is configured such that an amount of nitrogen is added to a flow of low-pressure hydrogen (having a pressure of not more than 17 bar) and sending the low pressure hydrogen and nitrogen to the suction side of the syngas compressor, where partially compressed hydrogen is mixed with nitrogen from a nitrogen source.

[0024] By feeding hydrogen at a low pressure to the suction side of the syngas compressor, the hydrogen compressor stages can be reduced and / or the rotational speed thereof can be lower than the rotational speed of currently available commercial hydrogen compressors. This makes the design of the compressors less demanding and may reduce the overall dimension of the hydrogen compression unit.

[0025] As defined herein, ammonia synthesis gas, often referred to as syngas, is a mixture of gases that serves as the primary feedstock for the production of ammonia in the Haber-Bosch process. The composition of this gas is carefully controlled to optimize the71PRO-511194-WO-2_ BHI0598PCT ammonia synthesis reaction, which combines nitrogen (N ) and hydrogen (H ) to form ammonia (NH3).

[0026] Turning now to the figures, FIG. 1 illustrates a schematic of an exemplary ammonia production system 100. The ammonia production system 100 comprises a hydrogen line 30 (which is in fluid communication with a hydrogen source 30A) and a nitrogen line 50 (which is in fluid communication with a nitrogen source 50A). In the exemplary embodiment of FIG. 1, the hydrogen line 30 may include an electrolyzer 130, which generates hydrogen gas. The electrolyzer can be powered with electric energy from an electric power distribution grid 140. In some embodiments, the electric energy can at least partly be provided by one or more renewable energy resources. By way of non-limiting example, in the schematic of FIG. 1 the renewable energy is solar energy. Energy from the renewable resource can be collected and converted into electric energy by an electric converter (not shown).

[0027] In FIG.l, the electric converter 150 includes photovoltaic panels and a solar inverter electrically coupled to the photovoltaic panels and to the electric power distribution grid 140

[0028] In other embodiments, not shown, other renewable energy resources can be used instead of, or in addition to, solar energy. For instance, wind, geothermal energy, wave and tidal energy, or the like can be used.

[0029] In some embodiments, the electric power distribution grid 140 is in electrical communication with a public power distribution grid, which is adapted to supply electric power in case of shortage of power from the renewable energy resource and / or to receive electric power from the electric converter 150, if the electric power obtained from the renewable energy resource exceeds the power needs of the electrolyzer. In other embodiments, not shown, other renewable energy resources can be used instead of, or in addition to, solar energy. For instance, wind, geothermal energy, wave and tidal energy, or the like can be used.

[0030] The hydrogen source 30A may provide hydrogen in the form of pure hydrogen gas having a purity of greater than 99 mole percent or in the form of a mixture of hydrogen gases with other hydrogen-containing compounds or hydrogen-containing compounds. Other hydrogen containing compounds may include water, ammonia, hydrocarbons (e.g., methane, ethane, propane, and the like), ammonia, hydrogen sulfide, hydrogen peroxide, or a combination thereof. Hydrogen-containing compounds may be mixed with pure hydrogen gas71PRO-511194-WO-2_ BHI0598PCT in amounts of upto to 5 mole percent, based on a total number of moles of the mixture of pure hydrogen gas and other hydrogen-containing compounds.

[0031] In an exemplary embodiment, the hydrogen source 30A delivers pure hydrogen gas having a purity of greater than 99 mole percent to a hydrogen compressor 60.

[0032] The nitrogen line 50 (which includes a source of nitrogen 50A) may include any arrangement configured to provide nitrogen, for instance by separation from ambient air. The nitrogen source 50 may provide nitrogen gas that has a purity of greater than 99 mole percent, nitrous oxide, nitrogen dioxide, ammonia and ammonia derivatives, primary amines, secondary amines, tertiary amines, hydrazine, or the like, or a combination thereof. In an exemplary embodiment, the nitrogen source 50 is pure nitrogen gas having a purity of greater than 99 mole percent.

[0033] In the embodiment of FIG. 1, the nitrogen source 50 includes an air purification and compression unit 80 that comprises an air compressor 80A and a nitrogen separation module 80B. The air purification and compression unit 80 lies downstream of the source of nitrogen 50. The nitrogen separation module 80B may include a membrane separator, a fractioning system, for instance, or any other device configured to separate nitrogen from the other air components, specifically oxygen and carbon dioxide.

[0034] The ammonia production system 100 further comprises an ammonia synthesis unit globally labeled 110. The ammonia synthesis unit 110 may include a compressor 110A and an ammonia synthesis module HOB. While a single compressor 110A is shown for the sake of simplification in the schematic of FIG.l, it shall be understood that the compressor 110A may in turn include a single compressor or a plurality of compressors, typically centrifugal compressors, arranged in parallel and / or in series, for example along the shaft line of a compressor train (not shown here).

[0035] The ammonia synthesis module HOB may include any arrangement configured to synthesize ammonia from a blend or mixture of hydrogen and nitrogen in gaseous form, delivered to the ammonia synthesis module 110B at a suitable pressure by the compressor 110A. In the present specification the compressor 110A will be referred to as syngas compressor 110A, as it is configured to compress the gas mixture containing nitrogen and hydrogen, which is desired for the ammonia synthesis.71PRO-511194-WO-2_ BHI0598PCT

[0036] The hydrogen is delivered by the hydrogen source 30 at a low hydrogen pressure Pl, for instance at around ambient pressure. The nitrogen source 50 delivers nitrogen at a low nitrogen pressure P2 toward the ammonia synthesis unit 110 through a nitrogen delivery line 120. The low nitrogen pressure P2 is higher than the hydrogen pressure Pl, due to the nature of the separation process performed by the nitrogen separation module 80B, which is fed with pressurized air by the air compressor 80A.

[0037] The nitrogen from the nitrogen source 50A flows through a main nitrogen delivery duct 120 to a suction side of the syngas compressor 110A. At the suction side of the syngas compressor 110A, the nitrogen is at a syngas suction pressure P3. The syngas suction pressure P3 is substantially equal to or slightly lower than the low nitrogen pressure P2, due to head losses along the main nitrogen delivery duct 120.

[0038] The ammonia production system 100 further comprises a hydrogen compression unit 60, the inlet whereof is fluidly coupled to the hydrogen source 30, and the outlet whereof is fluidly coupled to the suction side of the syngas compressor 110A. Since the low hydrogen pressure Pl is substantially lower than the syngas suction pressure P3, the hydrogen from the hydrogen source 30A is pressurized by the hydrogen compression unit 60, from the low hydrogen pressure Pl to the syngas suction pressure P3, or to a slightly higher pressure P3’, to take account of the head losses along the connection duct 170, which fluidly couples the delivery side of the hydrogen compression unit 60 to the syngas compressor 110A.

[0039] In an embodiment, pressure Pl is generally 0.5 to 5 bar, 0.75 bar to 1.25 bar, while pressure P3 is typically 5 to 17 bar, 10 to 15 bar. Pressure P2 may be slightly greater than P3 and may also range from 5 bar to 17 bar, 10 bar to 15 bar, though it is typically greater than P3 during the process. Conventional processes typically have pressure values downstream of the hydrogen compression unit and upstream of the syngas compression unit of typically 30 bar. This requires substantially compression stages when a rotary compressor unit is used to facilitate pressure increases.

[0040] In an embodiment, the hydrogen compression unit 60 of the instant specification comprises a compressor having 1 to 20 stages, 12 to 16 stages, when using a rotary compression unit. This is because of the lower pressure P3 of 5 to 17 bar. The number of stages presently used is reduced by at least 40%, at least 50%, when compared with conventional processes that utilize pressures of around 30 bar. The use of lower hydrogen compression pressures therefore71PRO-511194-WO-2_ BHI0598PCT facilitates a reduction in the number of compression stages when using either rotary compressors, reciprocating compressors, or a combination thereof.

[0041] In the schematic of FIG. 1, the hydrogen compression unit 60 is represented as a single compressor. It should, however, be understood that in general terms the hydrogen compression unit 60 may include one or more compressors, typically centrifugal compressors, which are usually arranged in series, and which may form a single compressor train with a plurality of compressors arranged along a common shaft line driven by a driver, not shown. Each compressor of the hydrogen compression unit 60 may in turn include a plurality of compressor stages.

[0042] The gas delivered by the hydrogen compression unit 60 and by the nitrogen source 50A flow together to the syngas compressor 110A, which thus processes a blend of hydrogen and nitrogen (typically termed “syngas”), boosting the pressure of the gas mixture from the syngas suction pressure P3 to the final pressure P4 required for the synthesis reaction performed in the ammonia synthesis module HOB. The final pressure after compression in the syngas compressor 110A is 150 to 200 bar.

[0043] The syngas pressure ratio in the present ammonia system 100 is therefore 10 to 20 (i.e., the pressure of gas emanating from the syngas compressor 110A ratioed against the pressure of hydrogen gas emanating from the hydrogen compression unit 60). The syngas pressure ratio in the conventional ammonia production systems (which have hydrogen compression unit pressures of 30 bar) is therefore 5 to 7.

[0044] In some embodiments, a control unit 27 is further functionally connected to a flowrate detection arrangement. In the embodiment of FIG.l, the flowrate detection arrangement is configured to detect the flowrate of the hydrogen along the hydrogen delivery line 30. Schematically, the flowrate detection arrangement includes a hydrogen flowmeter 29A in the hydrogen delivery line 30. In general terms, the flowrate detection arrangement is configured to detect a mass flow rate. In some embodiments, this can be obtained, e.g., using an orifice in combination with temperature and pressure measurements.

[0045] Based on the flowmeter signals, the control unit 27 is configured to adjust the percentage of the hydrogen delivered by the hydrogen line 30. Since the hydrogen is being compressed to low pressures in the hydrogen compression unit 60, the hydrogen compression unit 60 results in a reduction of the tip speed of the compressor impellers in the hydrogen71PRO-511194-WO-2_ BHI0598PCT compression unit 60 and / or a reduction of the number of impellers, and therefore possibly a reduction of the number of compressors of the hydrogen compression unit 60.

[0046] A compromise shall therefore be achieved, between the cost in terms of energy and power losses and the advantages in terms of reduction of the hydrogen compression unit speed and / or number of impellers and stages thereof.

[0047] In the embodiment of FIG. 1, the hydrogen compression unit 60 is shown as including two hydrogen compressors 60 and 70. The two hydrogen compressors 60 and 70 are arranged in series, the first hydrogen compressor 60 being arranged upstream of the second hydrogen compressor 70 with respect to the direction of the hydrogen flow through the hydrogen compression unit 60. The suction side of the first hydrogen compressor 60 receives hydrogen from the hydrogen source 30 at low hydrogen pressure Pl. Hydrogen at an intermediate hydrogen pressure P5 is delivered from the delivery side of the first hydrogen compressor 60 to the suction side of the second hydrogen compressor 70. The hydrogen pressure is boosted by the second hydrogen compressor 70 from the intermediate hydrogen pressure P5 to the syngas pressure P3 or to a slightly higher pressure P3’.

[0048] FIG.2 illustrates a flow chart summarizing the method performed by the ammonia production systems disclosed so far. In summary, the method includes the following. In 101 nitrogen is delivered to a suction side of the syngas compressor 110A. In 102 a low- pressure hydrogen flow is delivered to a suction side of the hydrogen compression unit 60. The compressed hydrogen and nitrogen is delivered to the syngas compressor 110A (see 103). Pressurized syngas from the syngas compressor 110A is delivered to the ammonia synthesis module HOB (104) and finally ammonia is synthetized in the ammonia synthesis module HOB from compressed syngas (105).

[0049] FIG. 3 illustrates a schematic of another exemplary embodiment for the ammonia production system 100. In this embodiment, the hydrogen pressure Pl delivered to the ammonia synthesis unit 110 and the nitrogen pressure P6 (after being expanded in a nitrogen turboexpander unit 160) delivered to the ammonia synthesis unit 110 are both approximately around 0.5 to 2 bar, which is substantially lower than the syngas pressure P4 delivered by the syngas compressor 110A (which is around 150 to 200 bar) to the ammonia converter HOB. The purpose of the mixing of hydrogen and nitrogen at lower pressure is to facilitate and easier pressurization of the mixture to the higher pressures P4 of 150 to 200 bar used for ammonia71PRO-511194-WO-2_ BHI0598PCT production. As noted above, pressurizing hydrogen from ambient conditions to higher values is laborious and expensive because of the low molecular weight of hydrogen. Combining hydrogen with nitrogen (which has a molecular weight 7 times that of hydrogen) reduces the amount of work that is to be conducted to facilitate the same increase in pressure. In view of the benefits achieved by the simultaneous pressurizing of a mixture of hydrogen and nitrogen, it is desirable to first bring both gases to the same low pressure (Pl for hydrogen and P2 for nitrogen) prior to transporting the mixture to the inlet of the syngas compressor 110A.

[0050] The desire to supply both gases to the inlet of the syngas compressor 110A at the same pressure may necessitate a reduction in the pressure of one of the gases from a hitherto supplied high pressure value (as obtained from a supplier or because of a preexisting manufacturing line set-up). In this embodiment, a nitrogen turboexpander unit 160 is installed inline retroactively into an existing production set-up that includes the nitrogen compression unit 80A and nitrogen separator 80B and that typically pressurizes the nitrogen to a pressure P2 of 8 bar to 17 bar. The nitrogen turboexpander unit 160 reduces the pressure from P2 (8 bar to 17 bar) to P6 (0.5 to 2.0 bar) so that both Pl (hydrogen pressure at 0.5 to 2 bar) and P6 (nitrogen pressure at 0.5 to 2.0 bar) are approximately equivalent to P3 (0.5 to 2.0 bar) the pressure at the inlet of the syngas compressor 110A are substantially identical. The expansion of the nitrogen gas in the nitrogen turboexpander unit to pressure P6 also enables the recovery of work that is expended in the compression of the hitherto compressed nitrogen which is at pressure P2.

[0051] Details are provided below with reference to the FIG. 3. The numerals in the FIG. 3 are the same as FIG. 1. The hydrogen is delivered by the hydrogen source 30A at a low hydrogen pressure Pl, such as, for example, at around ambient pressure (e.g., 1 bar).

[0052] The nitrogen source 50A delivers nitrogen at a low nitrogen pressure P6 toward the ammonia synthesis unit 110 through a nitrogen delivery line 120. The initial nitrogen pressure P2 (prior to the nitrogen being expanded in the nitrogen turboexpander unit 160) is 8 bar to 17 bar which is higher than the hydrogen pressure Pl, due to the nitrogen compression in air compressor 80A.

[0053] The hydrogen from the hydrogen source 30A flows through the hydrogen line 30 to a suction side of the syngas compressor 110A. At the suction side of the syngas compressor 110A, the hydrogen is at a syngas suction pressure P3 (which is 0.5 to 2 bar, around71PRO-511194-WO-2_ BHI0598PCT1 bar). The syngas suction pressure P3 is substantially equal to or slightly lower than the low hydrogen pressure Pl.

[0054] Since the high nitrogen pressure P2 is substantially higher than the syngas suction pressure P3, the nitrogen from the nitrogen source 50A is expanded by the nitrogen turboexpander unit 160, from the high nitrogen pressure P2 to the syngas suction pressure P3, or to a slightly higher pressure P3’, to take account of the head losses along the connection duct 180, which fluidly couples the delivery side of the nitrogen turboexpander unit 160 to the syngas compressor 110A. The nitrogen turboexpander unit 160, the inlet whereof is fluidly coupled to the nitrogen source 50 A, and the outlet whereof is fluidly coupled to the suction side of the syngas compressor 110A facilitates a reduction in pressure from P2 (8 to 17 bar) to P6 (0.5 to 2 bar), where P6 is approximately the same as Pl The nitrogen turboexpander unit 160 lies downstream of the air purification and compression unit 80 and upstream of the ammonia synthesis unit 110. The expansion of the nitrogen results in the recovery of energy (previously expended in the compression of the nitrogen gas), which may then be used for other purposes.

[0055] In the schematic of FIG. 3, the nitrogen turboexpander unit 160 is represented as a single turboexpander. It should, however, be understood that in general terms the nitrogen turboexpander unit 160 may include one or more turboexpanders which are usually arranged in series, and which may form a single turboexpander train with the plurality of turboexpanders arranged along a common shaft line driven by a driver, not shown. Each turboexpander of the nitrogen turboexpander unit 160 may in turn include a plurality of turboexpander stages.

[0056] The gas delivered by the nitrogen turboexpander unit 160 and by the hydrogen source 30A flow together to the syngas compressor 110A, which thus processes a blend of hydrogen and nitrogen (typically termed “syngas”), boosting the pressure of the gas mixture from the syngas suction pressure P3 (1 to 2 bar) to the final pressure P4 (150 to 200 bar), which is desirable for the synthesis reaction performed in the ammonia synthesis module HOB. The final pressure after compression in the syngas compressor 110A is 150 to 200 bar.

[0057] In an embodiment, with reference to FIG. 1, pressure Pl is generally 0.5 to 2 bar, 0.75 bar to 1.25 bar, while pressure P3 is typically 8 to 17 bar, 10 to 15 bar. Pressure P2 is greater than Pl and may also range from 8 bar to 17 bar, 10 bar to 15 bar. By expanding nitrogen, the pressure may be reduced from to P2 (8 to 17 bar) from P6 (0.5 to 5 bar, 1 to 271PRO-511194-WO-2_ BHI0598PCT bar). In an embodiment, the nitrogen is delivered to the syngas compressor at a pressure P3 of no greater than 5 bar. In another embodiment, the nitrogen is delivered to the syngas compressor at a pressure P3 of no greater than 2 bar. Conventional processes typically have pressure values upstream of the syngas compression unit of typically 30 bar. This requires a substantially large number of compression stages when a rotary compressor unit is used to facilitate pressure increases.

[0058] In an embodiment, the nitrogen turboexpander unit 160 of the instant specification comprises a turboexpander having 1 to 3 stages, 1 to 2 stages. This is because of the lower pressure P3 of 0.5 to 2 bar. The number of stages presently used is reduced by at least 40%, at least 50%, when compared with conventional processes that utilize pressures of around 30 bar.

[0059] A compromise shall therefore be achieved, between the cost in terms of energy and power losses and the advantages in terms of expanding nitrogen as opposed to compressing hydrogen.

[0060] FIG.4 illustrates a flow chart summarizing the method performed by the ammonia production systems disclosed in another embodiment. In summary, the method includes the following. In 201 hydrogen is delivered to a suction side of the syngas compressor 110A. In 202 a high-pressure nitrogen flow is delivered to a suction side of the turboexpander unit 160. The hydrogen and expanded nitrogen is delivered to the syngas compressor 110A (see 203). Pressurized syngas from the syngas compressor 110A is delivered to the ammonia synthesis module HOB (see 204) and finally ammonia is synthetized in the ammonia synthesis module HOB from compressed syngas (see 205).

[0061] Set forth below are some embodiments of the foregoing disclosure:

[0062] Embodiment 1 : An ammonia production system including a hydrogen source, a hydrogen compression unit, configured to compress hydrogen from the hydrogen source to a pressure of 8 bar to 17 bar, a nitrogen source, a syngas compressor, configured to receive nitrogen from the nitrogen source and hydrogen from the hydrogen compression unit, and further configured to compress a syngas including a mixture of hydrogen and nitrogen, and an ammonia synthesis module, fluidly coupled to the syngas compressor, wherein the nitrogen source is fluidly coupled to the hydrogen compression unit, such that in use the hydrogen compression unit compresses a blend containing hydrogen and nitrogen.71PRO-511194-WO-2_ BHI0598PCT

[0063] Embodiment 2: The system as in any prior embodiment, wherein the hydrogen compression unit comprises an inlet fluidly coupled to the hydrogen source and configured to receive hydrogen from the hydrogen source, and an outlet fluidly coupled to the syngas compressor.

[0064] Embodiment 3: The system as in any prior embodiment, wherein the hydrogen compression unit comprises at least a first hydrogen compressor and a second hydrogen compressor arranged in series.

[0065] Embodiment 4: The system as in any prior embodiment, wherein the flowrate detection arrangement comprises a hydrogen flowrate detection device configured to detect a hydrogen flowrate fed to the hydrogen compression unit.

[0066] Embodiment 5: The system as in any prior embodiment, wherein the hydrogen source comprises an electrolyzer.

[0067] Embodiment 6: The system as in any prior embodiment, wherein the electrolyzer is electrically coupled to an energy converting facility configured to convert energy from a renewable energy resource to electric energy.

[0068] Embodiment 7: The system as in any prior embodiment, wherein the nitrogen source is configured to separate nitrogen from air.

[0069] Embodiment 8: The system as in any prior embodiment, wherein the hydrogen is delivered to the syngas compressor at a pressure of no greater than 15 bar.

[0070] Embodiment 9: The system as in any prior embodiment, wherein the hydrogen is delivered to the syngas compressor at a pressure of no greater than 10 bar.

[0071] Embodiment 10: A method for producing ammonia from hydrogen and nitrogen, the method composing the following steps: delivering a nitrogen flow at a syngas suction pressure to a suction side of a syngas compressor, delivering a hydrogen flow at a hydrogen inlet pressure, lower than the syngas suction pressure, to a suction side of a hydrogen compression unit; where the hydrogen inlet pressure is 8 to 17 bar, boosting the pressure of the hydrogen flow from the hydrogen inlet pressure to the syngas suction pressure in the hydrogen compression unit and delivering the compressed hydrogen to the syngas compressor, and71PRO-511194-WO-2_ BHI0598PCT delivering pressurized syngas from the syngas compressor to an ammonia synthesis module and produce ammonia from the compressed syngas.

[0072] Embodiment 11: The method as in any prior embodiment, further comprising the steps of: delivering a main nitrogen flow at the syngas pressure from a nitrogen source; diverting a nitrogen secondary flow from the main nitrogen flow; reducing pressure of the nitrogen secondary flow to a reduced nitrogen pressure; and delivering the nitrogen secondary flow at the reduced nitrogen pressure to the hydrogen compression unit.

[0073] Embodiment 12: The method as in any prior embodiment, wherein the hydrogen compression unit comprises a first hydrogen compressor and a second hydrogen compressor arranged in series, the first hydrogen compressor being arranged upstream of the second hydrogen compressor with respect to the hydrogen flow in the hydrogen compression unit.

[0074] Embodiment 13: The method as in any prior embodiment, wherein the hydrogen compression unit comprises a first hydrogen compressor and a second hydrogen compressor arranged in series, the first hydrogen compressor being arranged upstream of the second hydrogen compressor with respect to the hydrogen flow in the hydrogen compression.

[0075] Embodiment 14: The method as in any prior embodiment, wherein the hydrogen is delivered to the syngas compressor at a pressure of no greater than 15 bar.

[0076] Embodiment 15: The method as in any prior embodiment, wherein the hydrogen is delivered to the syngas compressor at a pressure of no greater than 10 bar.

[0077] Embodiment 16: An ammonia production system including a hydrogen source, a nitrogen source, a nitrogen turboexpander unit, configured to expand nitrogen from the nitrogen source to a pressure of 0.1 bar to 5 bar, a syngas compressor, configured to receive nitrogen from the nitrogen turboexpander and hydrogen from the hydrogen source, and further configured to compress a syngas including a mixture of hydrogen and nitrogen, and an ammonia synthesis module, fluidly coupled to the syngas compressor; where the ammonia synthesis module is operative to convert the syngas into ammonia.

[0078] Embodiment 17: The system as in any prior embodiment, wherein the nitrogen turboexpander unit comprises an inlet fluidly coupled to the nitrogen source and configured to71PRO-511194-WO-2_ BHI0598PCT receive nitrogen from the nitrogen source, and an outlet fluidly coupled to the syngas compressor.

[0079] Embodiment 18: The system as in any prior embodiment, wherein the nitrogen turboexpander unit comprises at least a first nitrogen turboexpander and optionally a second nitrogen turboexpander arranged in series with the first nitrogen turboexpander.

[0080] Embodiment 19: The system as in any prior embodiment, wherein the nitrogen source is in fluid communication with a nitrogen separator that purifies nitrogen delivered to the syngas compressor.

[0081] Embodiment 20: The system as in any prior embodiment, wherein the nitrogen is delivered to the syngas compressor at a pressure of no greater than 5 bar.

[0082] Embodiment 21: The system as in any prior embodiment, wherein the nitrogen is delivered to the syngas compressor at a pressure of no greater than 1 bar.

[0083] Certain exemplary embodiments have been described to provide an overall understanding of the principles of the structure, function and use of the systems, devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the systems, devices and methods specifically described herein and illustrated in the accompanying drawings are nonlimiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. Features described or illustrated in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention.

Claims

71PRO-511194-WO-2_ BHI0598PCTClaims1. An ammonia production system characterized by: a hydrogen source (30); a hydrogen compression unit (60), configured to compress hydrogen from the hydrogen source (30) to a pressure of 0.1 bar to 17 bar; a nitrogen source (50); a syngas compressor (110A), configured to receive a mixture of hydrogen and nitrogen including nitrogen from the nitrogen source (50) and hydrogen from the hydrogen compression unit (60), and further configured to compress a syngas including the mixture of hydrogen and nitrogen; and an ammonia synthesis module (HOB), fluidly coupled to the syngas compressor (H0A); wherein the ammonia synthesis module (HOB) further processes the mixture of hydrogen and nitrogen from the syngas compressor (110A).

2. The system of claim 1, wherein the hydrogen compression unit (60) comprises an inlet fluidly coupled to the hydrogen source (30) and configured to receive hydrogen from the hydrogen source (30), and an outlet fluidly coupled to the syngas compressor (110A).

3. The system of claim 1 or 2, wherein the hydrogen compression unit (60) comprises at least a first hydrogen compressor (60) and a second hydrogen compressor (70) arranged in series.

4. The system of claim any one of the preceding claims, wherein the flowrate detection arrangement comprises a hydrogen flowrate detection device (29 A) configured to detect a hydrogen flowrate fed to the hydrogen compression unit (60).

5. The system of any one of the preceding claims, wherein the hydrogen source (30) comprises an electrolyzer (130).71PRO-511194-WO-2_ BHI0598PCT6. The system of claim 5, wherein the electrolyzer (130) is electrically coupled to an energy converting facility configured to convert energy from a renewable energy resource to electric energy.

7. The system of any one of the preceding claims, wherein the nitrogen source (50) is configured to separate nitrogen from air.

8. The system of any one of the preceding claims, wherein the hydrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 15 bar.

9. The system of any one of the preceding claims, wherein the hydrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 10 bar.

10. A method for producing ammonia from hydrogen and nitrogen, the method composing the following steps: delivering a nitrogen flow at a syngas suction pressure to a suction side of a syngas compressor (110A); delivering a hydrogen flow at a hydrogen inlet pressure, lower than the syngas suction pressure, to a suction side of a hydrogen compression unit (60); where the hydrogen inlet pressure is 0.1 to 17 bar; boosting the pressure of the hydrogen flow from the hydrogen inlet pressure to the syngas suction pressure in the hydrogen compression unit (60) and delivering the compressed hydrogen to the syngas compressor (110A); and delivering pressurized syngas from the syngas compressor (110A) to an ammonia synthesis module (HOB) and produce ammonia from the compressed syngas.

11. The method of claim 10, further comprising the steps of: delivering a main nitrogen flow at the syngas pressure from a nitrogen source (50); diverting a nitrogen secondary flow from the main nitrogen flow; reducing pressure of the nitrogen secondary flow to a reduced nitrogen pressure; and delivering the nitrogen secondary flow at the reduced nitrogen pressure to the hydrogen compression unit (60).

12. The method of any one of claims 10 and 11, wherein the hydrogen compression unit (60) comprises a first hydrogen compressor (60) and a second hydrogen compressor (70)71PRO-511194-WO-2_ BHI0598PCT arranged in series, the first hydrogen compressor (60) being arranged upstream of the second hydrogen compressor (70) with respect to the hydrogen flow in the hydrogen compression unit (60).

13. The method of any one of claims 10 to 12, wherein the hydrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 15 bar.

14. The method of any one of claims 10 to 13, wherein the hydrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 10 bar.

15. An ammonia production system characterized by: a hydrogen source (30); a nitrogen source (50); a nitrogen turboexpander unit (160), configured to expand nitrogen from the nitrogen source (50) to a pressure of 0.1 bar to 17 bar; a syngas compressor (110A), configured to receive a mixture of hydrogen and nitrogen including nitrogen from the nitrogen turboexpander unit (160) and hydrogen from the hydrogen source (30), and further configured to compress a syngas including the mixture of hydrogen and nitrogen; and an ammonia synthesis module (HOB), fluidly coupled to the syngas compressor (110A); where the ammonia synthesis module (HOB) is operative to further process the mixture of hydrogen and nitrogen from the syngas compressor (110A).

16. The system of claim 15, wherein the nitrogen turboexpander unit (160) comprises an inlet fluidly coupled to the nitrogen source and configured to receive nitrogen from the nitrogen source (50), and an outlet fluidly coupled to the syngas compressor (110A).

17. The system of claim 15 or 16, wherein the nitrogen turboexpander unit (160) comprises at least a first nitrogen turboexpander and optionally a second nitrogen turboexpander arranged in series with the first nitrogen turboexpander.71PRO-511194-WO-2_ BHI0598PCT18. The system of any one of the preceding claims, wherein the nitrogen source (50) is in fluid communication with a nitrogen separator (80B) that purifies nitrogen delivered to the syngas compressor (110A).

19. The system of any one of the preceding claims, wherein the nitrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 5 bar.

20. The system of any one of the preceding claims, wherein the nitrogen is delivered to the syngas compressor (110A) at a pressure of no greater than 1 bar.

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