Process for green ammonia production

Abstract

Disclosed herein is an ammonia production system comprising a nitrogen compression unit that is configured to compress nitrogen from a nitrogen source to a pressure of 100 bar to 300 bar; a hydrogen expander unit configured to expand hydrogen from the a hydrogen source to a pressure of 100 bar to 300 bar; an ammonia synthesis module fluidly coupled directly to the nitrogen compression unit and the hydrogen expander unit; where the ammonia synthesis module converts the hydrogen and nitrogen into ammonia; where the ammonia production system is devoid of a syngas compressor.

Description

[0001] 71 PRO-511195 -WO-2_BHI0599PCT

[0002] PROCESS FOR GREEN AMMONIA PRODUCTION

[0003] CROSS REFERENCE TO RELATED APPLICATIONS

[0004] This application claims the benefit of IT Application No. 102024000026619, filed on November 26, 2024, which is incorporated herein by reference in its entirety.

[0005] TECHNICAL FIELD

[0006]

[0001] 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.

[0007] BACKGROUND ART

[0008]

[0002] 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, but has also a potential as energy vector, especially if produced with energy from renewable sources.

[0009]

[0003] Ammonia production usually starts from a feed gas, which provides a source of hydrogen, such as methane, for instance. Nitrogen is obtained from air.

[0010]

[0004] 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 manner of manufacturing green ammonia is by using nitrogen separated from air along with hydrogen obtained via 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.

[0011]

[0005] 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. 71 PRO-511195 -WO-2_BHI0599PCT

[0012]

[0006] Compressing a gas that has 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.

[0013]

[0007] 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.

[0014]

[0008] 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.

[0015] SUMMARY

[0016]

[0009] Disclosed herein is an ammonia production system comprising a nitrogen compression unit that is configured to compress nitrogen from a nitrogen source to a pressure of 100 bar to 300 bar; a hydrogen expander unit configured to expand hydrogen from the a hydrogen source to a pressure of 100 bar to 300 bar; an ammonia synthesis module fluidly coupled directly to the nitrogen compression unit and the hydrogen expander unit; where the ammonia synthesis module converts the hydrogen and nitrogen into ammonia; where the ammonia production system is devoid of a syngas compressor.

[0017]

[0010] Disclosed herein is a method for producing ammonia from hydrogen and nitrogen, the method comprising delivering a nitrogen gas to a nitrogen compression unit; compressing the nitrogen gas from the nitrogen inlet pressure to the inlet pressure of an ammonia synthesis module. The method further comprises delivering a hydrogen gas to a suction side of a hydrogen expander unit and expanding the hydrogen gas from a supply pressure of 200 to 500 bar to the inlet pressure of an ammonia synthesis module. The compressed nitrogen and the expanded hydrogen are charged to the ammonia synthesis module where they are reacted to produce ammonia. 71 PRO-511195 -WO-2_BHI0599PCT

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] [Oil] Reference is now made briefly to the accompanying drawings, in which:

[0020]

[0012] FIG. 1 is a schematic of an exemplary ammonia production system; and

[0021]

[0013] FIG. 2 is a flowchart summarizing a method according to the present disclosure.

[0022] DETAILED DESCRIPTION

[0023]

[0014] Disclosed herein is a system for ammonia synthesis, including novel features configured to simplify the structure or the design of a hydrogen compression unit. The system comprises supplying a mixture of hydrogen and nitrogen (referred to as syngas) to an ammonia synthesis module at a pressure normally used by the ammonia synthesis module without using a syngas compressor. Disclosed herein is system that comprises an ammonia synthesis module that receives hydrogen gas at a reduced pressure of approximately 150 bar (from an initial higher pressure of 300 bar in a storage tank) and nitrogen gas at an increased pressure of approximately 150 bar (from an initial lower pressure of 10 bar). Because the pressure of the incoming hydrogen and nitrogen are equivalent to the pressures normally supplied by a syngas compressor, the syngas compressor may be excluded from the system for producing ammonia.

[0024]

[0015] Under normal circumstances, a syngas compressor facilitates an increase in pressure of the syngas to 100 to 300 bar (which is the inlet pressure of the ammonia synthesis module) from a pressure of 5 to 17 bar. The syngas compressor supplies the syngas to an ammonia synthesis module where it is converted to ammonia. Since the nitrogen and hydrogen are supplied at suitable pressures to the ammonia synthesis module, the syngas compressor may be bypassed or excluded from the system.

[0025]

[0016] 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 (NHs).

[0026]

[0017] 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 is in fluid communication with a high-pressure hydrogen storage tank (30A) that stores the hydrogen at a pressure of 175 to 500 bar, or 175 to 300 bar. The ammonia 71 PRO-511195 -WO-2_BHI0599PCT synthesis module operates at a pressure of 100 to 300 bar. It is therefore desirable to reduce the hydrogen pressure from 175 to 500 bar to at least 100 to 300 bar.

[0027]

[0018] 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 gas 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.

[0028]

[0019] 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.

[0029]

[0020] 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 50A 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 50A is pure nitrogen gas having a purity of greater than 99 mole percent.

[0030]

[0021] Disposed in the hydrogen line 30 and located downstream of the hydrogen storage 30A is an expander 160 that facilitates an expansion of the hydrogen while simultaneously reducing hydrogen pressure from 175 to 500 bar to 100 to 300 bar. The expander is a high-speed mechanical device used to extract energy from a high-pressure gas stream by expanding it to a lower pressure. This expansion process produces mechanical work, which is typically used to drive a generator, compressor, or other rotating equipment. The hydrogen gas enters the expander at high pressure and expands through the blades. During expansion, the gas cools though a quasi-isentropic transformation and does work on the expander. The mechanical energy generated in the expander may be harnessed to drive other processes.

[0031]

[0022] In the embodiment of FIG. 1 , the nitrogen line 50 comprises a nitrogen source 50A and further includes a nitrogen purification and compression unit 80 that comprises a first nitrogen compressor 80A and a nitrogen separation module 80B. The nitrogen source 50A contains nitrogen at a pressure of 5 to 17 bar. The nitrogen purification and compression unit 71 PRO-511195 -WO-2_BHI0599PCT

[0032] 80 lies downstream of the nitrogen source 50A. 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.

[0033]

[0023] In an embodiment, the first nitrogen compressor 80 A facilitates an increase in the pressure of nitrogen gas from 5 to 17 bar to pressure P2 value of 150 bar. This increase in the pressure of the nitrogen may be accomplished by using a compressor that performs the increase in a plurality of stages.

[0034]

[0024] In an embodiment, located downstream of the first nitrogen compressor 80A is an optional second nitrogen compression system 75 that contains a second nitrogen compressor 60 and a third nitrogen compressor 70. The nitrogen compression system 75 receives the compressed nitrogen from the first nitrogen compressor 80A at a pressure of less than 150 bar and boosts it to 150 bar at which pressure it is supplied to the ammonia synthesis module via line 180.

[0035]

[0025] The two nitrogen compressors 60 and 70 are arranged in series, the second nitrogen compressor 60 being arranged upstream of the third nitrogen compressor 70 with respect to the direction of the nitrogen flow through the nitrogen compressor 60. The suction side of the first hydrogen compressor 60 receives nitrogen from the first nitrogen compressor 80A and the air separator 80B at a pressure of less than the desired 150 bar. Nitrogen at an intermediate hydrogen pressure P5 is delivered from the delivery side of the second nitrogen compressor 60 to the suction side of the third nitrogen compressor 70. The nitrogen pressure is boosted by the third nitrogen compressor 70 from the intermediate nitrogen pressure P5 to the desired pressure of 100 to 300 bar (which is the inlet pressure desired by the ammonia synthesis module HOB).

[0036]

[0026] 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 from the hydrogen expander and the nitrogen compressor. In the present specification the hydrogen and nitrogen are delivered to the ammonia synthesis module in a molar ratio of 1 :3 to 1 :7 respectively, or 1 :3 to 1 :5 respectively. The ammonia synthesis module lies downstream of both the hydrogen expander 160 and the nitrogen compressors 80A, 60 and 70, when nitrogen compressors 60 and 70 are present in the system 100. The ammonia synthesis module is in direct fluid communication with both the 71 PRO-511195 -WO-2_BHI0599PCT hydrogen expander 160 and at least one of the nitrogen compressors 80A, 60 and 70. The system 100 is devoid of a syngas compressor.

[0037]

[0027] The ammonia synthesis module uses the Haber-Bosch process, a catalytic chemical reaction that combines nitrogen (N?) from the air and hydrogen (H?) under high pressure and temperature to produce ammonia.

[0038]

[0028] FIG.2 illustrates a flow chart summarizing the method performed by the ammonia production systems disclosed herein. In summary, the method includes the following. In 201 nitrogen is delivered to a suction side of the nitrogen compression unit (80). In 202, a high-pressure hydrogen flow is delivered to a suction side of the hydrogen expander unit 160. The expanded hydrogen and compressed nitrogen are delivered to an ammonia converter HOB (see 203). Ammonia is synthetized in the ammonia converter HOB from the expanded hydrogen and the compressed nitrogen (205).

[0039]

[0029] This method is advantageous in that it avoids the use of a syngas compressor. Hydrogen delivered to the facility at pressures of 175 to 500 bar is used for energy extraction by lowering its pressure to 100 to 300 bar.

[0040]

[0030] Set forth below are some embodiments of the foregoing disclosure:

[0041]

[0031] Embodiment 1: An ammonia production system including a nitrogen compression unit, configured to compress nitrogen from a nitrogen source to a pressure of 100 bar to 300 bar, a hydrogen expander unit, configured to expand hydrogen from a hydrogen source to a pressure of 100 bar to 300 bar, an ammonia synthesis module, fluidly coupled directly to the nitrogen compression unit and the hydrogen expander unit; where the ammonia synthesis module converts the hydrogen and nitrogen into ammonia; where the ammonia production system is devoid of a syngas compressor.

[0042]

[0032] Embodiment 2: The system as in any prior embodiment, wherein the hydrogen source comprises a high-pressure storage tank.

[0043]

[0033] Embodiment 3: The system as in any prior embodiment, wherein the high- pressure storage tank stores hydrogen at pressures of 175 to 500 bar.

[0044]

[0034] Embodiment 4: The system as in any prior embodiment, wherein the hydrogen expander unit comprises an inlet fluidly coupled to the hydrogen source and configured to receive hydrogen from a hydrogen source, and an outlet fluidly coupled to the ammonia synthesis module.

[0045]

[0035] Embodiment 5: The system as in any prior embodiment, wherein the nitrogen compression unit comprises an inlet fluidly coupled to a nitrogen source and configured to 71 PRO-511195 -WO-2_BHI0599PCT receive nitrogen from the nitrogen source, and an outlet fluidly coupled to the ammonia synthesis module.

[0046]

[0036] Embodiment 6: The system as in any prior embodiment, wherein the nitrogen compression unit comprises at least a first nitrogen compressor and a second nitrogen compressor arranged in series.

[0047]

[0037] Embodiment 7: 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 expander unit.

[0048]

[0038] Embodiment 8: The system as in any prior embodiment, wherein the nitrogen source lies upstream of an air separator that is configured to separate nitrogen from air.

[0049]

[0039] Embodiment 9: A method for producing ammonia from hydrogen and nitrogen, the method including delivering nitrogen gas a nitrogen compression unit, compressing the nitrogen gas to an inlet pressure of an ammonia synthesis module, expanding a hydrogen gas from a supply pressure of 200 to 300 bar to the inlet pressure of an ammonia synthesis module, charging the compressed nitrogen gas and the expanded hydrogen gas to the ammonia synthesis module, and producing ammonia from the compressed syngas.

[0050]

[0040] Embodiment 10: The method as in any prior embodiment, wherein the inlet pressure of the ammonia synthesis module is 150 to 200 bar.

[0051]

[0041] 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

71 PRO-511195 -WO-2_BHI0599PCTCLAIMSWhat is claimed:

1. An ammonia production system characterized by: a nitrogen compression unit (80), configured to compress nitrogen from a nitrogen source (50A) to a pressure of 100 bar to 300 bar; a hydrogen expander unit (160), configured to expand hydrogen from a hydrogen source to a pressure of 100 bar to 300 bar; an ammonia synthesis module (HOB), fluidly coupled directly to the nitrogen compression unit (80) and the hydrogen expander unit (160); where the ammonia synthesis module (HOB) converts the hydrogen and nitrogen into ammonia; where the ammonia production system is devoid of a syngas compressor, wherein the hydrogen and nitrogen enter separately into the ammonia synthesis module (110B) and are blended afterwards.

2. The system of claim 1, wherein the hydrogen source comprises a high- pressure storage tank (30A).

3. The system of claim 2, wherein the high-pressure storage tank (30 A) stores hydrogen at pressures of 175 to 500 bar.

4. The system of claim 1, wherein the hydrogen expander unit (160) comprises an inlet fluidly coupled to the hydrogen source and configured to receive hydrogen from a hydrogen source, and an outlet fluidly coupled to the ammonia synthesis module (110B).

5. The system of claim 1, wherein the nitrogen compression unit (80) comprises an inlet fluidly coupled to a nitrogen source and configured to receive nitrogen from the nitrogen source, and an outlet fluidly coupled to the ammonia synthesis module (110B).

6. The system of claim 1 or 2, wherein the nitrogen compression unit (80) comprises at least a first nitrogen compressor (80A) and a second nitrogen compressor (60) arranged in series.

7. The system of any one of the preceding claims, wherein a flowrate detection arrangement comprises a hydrogen flowrate detection device configured to detect a hydrogen flowrate fed to the hydrogen expander unit (160).

8. The system of any one of the preceding claims, wherein the nitrogen source lies upstream of an air separator (80B) that is configured to separate nitrogen from air.

9. A method for producing ammonia from hydrogen and nitrogen, the method characterized by:871 PRO-511195 -WO-2_BHI0599PCT delivering nitrogen gas a nitrogen compression unit (80); compressing the nitrogen gas to an inlet pressure of an ammonia synthesis module (HOB); expanding a hydrogen gas from a supply pressure of 200 to 300 bar to the inlet pressure of an ammonia synthesis module (HOB); charging the compressed nitrogen gas and the expanded hydrogen gas to the ammonia synthesis module (HOB); and producing ammonia from the compressed syngas.

10. The method of any one of claims 9 and 10, wherein the inlet pressure of the ammonia synthesis module (110B) is 150 to 200 bar.

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