Hydrogen and nitrogen blending system

Abstract

The present invention relates to a hydrogen and nitrogen blending system, comprising a gas compressor (4) configured to compress a gas comprising a mixture of hydrogen and nitrogen, so that a compressed gas is generated. The gas compressor (4) comprises an inlet (4A) to receive the gas, and an outlet (4B) for the compressed gas. The hydrogen and nitrogen blending system further comprises a separator (5) fluidly coupled with to the outlet (4B) of the gas compressor (4) and configured to receive the compressed gas and to separate hydrogen and nitrogen from the compressed gas.

Description

Hydrogen and nitrogen blending systemDescriptionTECHNICAL FIELD

[0001] The present disclosure concerns a hydrogen and nitrogen blending system. Specifically, disclosed herein a blending system adapted to provide as output hydrogen and nitrogen which can be used independently for different purposes.BACKGROUND ART

[0002] 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. Furthermore, the large number of compressors stages implies higher costs due to compressor stages themselves and high maintenance costs.

[0003] Hydrogen is the gas having the lowest molecular weight and therefore is particularly demanding in terms of compressor performances.

[0004] The need to compress hydrogen from a pressure, at which it is produced, up to a pressure needed for example for an efficient ammonia synthesis reaction and liquefaction 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 are used.

[0005] The mixture of hydrogen and nitrogen compressed by a hydrogen compression unit has a molecular weight which is higher than the molecular weight of pure hydrogen. If at least a part of the hydrogen compression is performed with the hydrogen being mixed to nitrogen, the hydrogen compressor stages can be reduced and / or as well as the rotational speed of the compressors.

[0006] Therefore, in order to increase the molecular weight of the gas compressed bythe hydrogen compression unit and make the design of the hydrogen compressors less challenging, for instance in order to reduce the rotational speed or the number of compressor impellers needed to boost the hydrogen pressure (appropriate for the gas compressor), a certain amount of nitrogen is added to the hydrogen prior to or during compression in the hydrogen compression unit.

[0007] This is the technical teaching of the international patent application WO 2023 / 078583 Al directed to an ammonia synthesis plant comprising a blending system wherein nitrogen and hydrogen are mixed to form a gas.

[0008] Accordingly, there is a need to provide an improved blending system.SUMMARY

[0009] In one aspect of the invention, the subject matter disclosed herein is directed to an improved hydrogen and nitrogen blending system. The hydrogen and nitrogen blending system comprises a gas compressor configured to compress a gas comprising a mixture of hydrogen and nitrogen, so that a compressed gas is generated, as well as a separator fluidly coupled the gas compressor and configured to receive the compressed gas and to separate hydrogen and nitrogen from the compressed gas.

[0010] In another aspect of the invention, the hydrogen and nitrogen blending system can comprise a hydrogen storage unit to store at least a portion of the hydrogen separated by the separator and / or an energy recovery unit configured to recover energy from the nitrogen separated by the separator.

[0011] Particularly, if the hydrogen and nitrogen blending system comprises the energy recover unit, the latter can comprise a gas expander. A gas expander converts pressure energy into electrical energy. The gas expansion process is crucial for the efficient production of energy in a gas network infrastructure. The conversion allows to recover at least partially the energy previously used on compressing the gas.

[0012] In another aspect the subject matter is directed to a method of operating a hydrogen and nitrogen blending system mentioned above.

[0013] The method comprises the following steps: receiving from the separator a gas comprising a mixture of hydrogen and nitrogen, and separating hydrogen and nitrogenfrom the gas by the separator.

[0014] In another aspect of the invention, the method can comprise the step of storing hydrogen separated by the separator in a hydrogen storage unit and / or the step of recovering energy from the nitrogen separated by the separator in an energy recovery unit.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:Fig. 1 illustrates a schematic view of a first embodiment of the hydrogen and nitrogen blending system according to the invention;Fig. 2 illustrates a schematic view of a second embodiment of the hydrogen and nitrogen blending system according to the invention;Fig. 3 shows a flow chart of a method of operating the blending system according to the invention.DETAILED DESCRIPTION

[0016] In the field of blending systems, a hydrogen and nitrogen blending system is designed to compress a gas comprising a mixture of hydrogen and nitrogen and to separate hydrogen and nitrogen from the compressed gas with the possibility to use hydrogen and nitrogen independently of each other for different purposes.

[0017] Reference is now made to the drawings and particularly to Figure 1 that shows a schematic view of a first embodiment of the hydrogen and nitrogen blending system according to the invention.

[0018] The hydrogen and nitrogen blending system comprises a gas compressor 4 configured to compress a gas comprising a mixture of hydrogen and nitrogen, so that a compressed gas is generated.

[0019] The gas compressor comprises an inlet 4A to receive the gas, and an outlet 4B for the compressed gas.

[0020] Although not shown in Figure 1, the gas compressor 4 can be a multi-stage compressor.

[0021] The hydrogen and nitrogen of the mixture of hydrogen and nitrogen are compressed by the gas compressor 4. Therefore, at the outlet 4B of the gas compressor 4, the hydrogen and nitrogen of the mixture of hydrogen and nitrogen will have a higher pressure than the pressure of the hydrogen and nitrogen of the same mixture of hydrogen and nitrogen at the inlet 4B of the gas compressor 4. The gas compressor 4 is a high pressure compressor.

[0022] The hydrogen and nitrogen blending system further comprises a separator 5 fluidly coupled with to the outlet 4B of the gas compressor 4 and configured to receive the compressed gas and to separate hydrogen and nitrogen from the compressed gas.

[0023] The separator 5 comprises an inlet 5A to receive the compressed gas, as well as a first outlet 5B for the hydrogen separated from the gas and a second outlet 5C for the nitrogen separated from the gas.

[0024] In particular, the inlet 5A of the separator 5 is connected through a first line LI to the outlet 4B of the gas compressor 4.

[0025] In the first embodiment that is described, it is preferable that the hydrogen and nitrogen blending system comprises a hydrogen storage unit 6 to store the hydrogen separated by the separator 5.

[0026] The hydrogen storage unit 6 comprises an inlet 6A to receive the hydrogen separated from the gas.

[0027] The inlet 6A of the hydrogen storage unit 6 is fluidly coupled to the first outlet 5B of the separator 5.

[0028] In particular, the inlet 6A of the hydrogen storage unit 6 is connected through a second line L2 to the first outlet 5B of the separator 5.

[0029] However, in a first variant not shown in Figures, the hydrogen storage unit 6can store at least a portion of the hydrogen separated by the separator 5, without departing from the scope of the invention.

[0030] In this first variant, the remaining portion of the hydrogen separated by the separator 5 can be used for different purposes.

[0031] In a second variant not shown in Figures, the hydrogen storage unit 6 is not included in the hydrogen and nitrogen blending system. Therefore, the hydrogen separated by the separator 5 can be directly used for different purposes.

[0032] Furthermore, it is preferable that the hydrogen and nitrogen blending system comprises an energy recovery unit 7 configured to recover energy from the nitrogen separated by the separator 5.

[0033] Although in the first embodiment that is described both the hydrogen storage unit 6 and the energy recovery unit 7 are shown in Figure 1, the hydrogen and nitrogen blending system can comprise the energy recovery unit 7 as an alternative or in addition to the hydrogen storage unit 6.

[0034] The energy recovery unit 7 comprises an inlet 7A to receive the nitrogen separated from the gas.

[0035] The inlet 7A of energy recovery unit 7 is fluidly coupled to the second outlet 5C of the separator 5.

[0036] In particular, the inlet 7A of energy recovery unit 7 is connected through a third line L3 to the second outlet 5C of the separator 5.

[0037] Advantageously, the energy recovery unit 7 can comprise a gas expander to expand the nitrogen separated from the hydrogen by the separator 5.

[0038] In the first embodiment, the hydrogen and nitrogen blending system comprises a hydrogen source 1 to deliver hydrogen, and a nitrogen source 2 to deliver nitrogen.

[0039] The inlet 4A of the gas compressor 4 is fluidly coupled with the hydrogen source 1 and the nitrogen source 2.

[0040] The hydrogen and the nitrogen of the mixture of hydrogen and the nitrogen arethe hydrogen delivered from the hydrogen source 1 and the nitrogen delivered from the nitrogen source 2, respectively.

[0041] The gas compressor 4 is connected to the hydrogen source and the nitrogen source 2 through a mixing line LM.

[0042] Figure 2 shows a schematic view of a second embodiment of the hydrogen and nitrogen blending system according to the invention.

[0043] Differently from the hydrogen and nitrogen blending system described in the first embodiment, in the second embodiment the hydrogen and nitrogen blending system comprises a gas source 3 to deliver the gas.

[0044] The inlet 4A of the gas compressor 4 is fluidly coupled with the gas source 3.

[0045] In particular, the gas source 3 comprises an outlet 3B and the inlet 4A of the gas compressor 4 is fluidly coupled with the outlet 3B of the gas source 3. The inlet 4A of the gas compressor 4 is connected to the outlet 3B of the gas source 3 through a feed line LF.

[0046] The present invention also relates to a method 1000 of operating a hydrogen and nitrogen blending system described above. The flow chart of the method 1000 is shown in Figure 3.

[0047] The method 1000 comprises the following steps: compressing 100 a gas comprising a mixture of hydrogen and nitrogen by means of the gas compressor 4; receiving 101, at the separator 5, from the gas compressor 4 the gas comprising a mixture of hydrogen and nitrogen; and separating 102 hydrogen and nitrogen from the gas by the separator 5.

[0048] It is preferable that the method 1000 can comprise the step of storing 103 the hydrogen separated by the separator 5 in a hydrogen storage unit 6.

[0049] However, as previously said for the hydrogen and nitrogen blending system described above, the method 1000 can comprise the step of storing 103 at least a por-tion of the hydrogen separated by the separator 5 in the hydrogen storage unit 6, without departing from the scope of the invention, so that the remaining portion of the hydrogen separated by the separator 5 can be used for different purposes.

[0050] In any case, the step of storing 103 totally o partially the hydrogen separated by the separator 5 of the hydrogen and nitrogen blending system is not necessary, so that the hydrogen separated by the separator 5 can be directly used for different purposes, without departing from the scope of the invention.

[0051] Furthermore, the method 1000 can comprise the step of recovering 104 energy from the nitrogen separated by the separator 5 in an energy recovery unit 7.

[0052] In particular, the method 1000 can comprise the step of recovering energy from the nitrogen separated by the separator 5 in an energy recovery unit 7 as an alternative or in addition to the step of storing hydrogen separated by the separator 5 in a hydrogen storage unit 6.

[0053] A first advantage of the hydrogen and nitrogen blending system object of the invention is given by the possibility of independently using hydrogen and nitrogen (which are initially included in a gas mixture of a gas) separated by the hydrogen and nitrogen blending system itself. For example, on the hand, the hydrogen can be stored in a hydrogen storage unit of the blending system to be used when needed and / or directed to the end users who can use it for different purposes. On the other hand, the nitrogen can be expanded in order to generate an energy to be used for different purpose.

[0054] A further advantage is that the blending system object of the invention can be used in different technology fields, such as in the field of reciprocating compressor, gas turbine systems, steam turbines, electrical machine and VFD compressor, energy storage, etc..

[0055] While aspects of the invention have been described in terms of various specific embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless specified otherwise herein, the order or sequence of any process or method steps may be varied or re-sequenced according toalternative embodiments.

[0056] Reference has been made in detail to the embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Reference throughout the specification to "one embodiment" or "an embodiment" or “some embodiments” means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.

[0057] When elements of various embodiments are introduced, the articles “a”, “an”,“the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

CLAIMS1. A hydrogen and nitrogen blending system, comprising: a gas compressor (4) configured to compress a gas comprising a mixture of hydrogen and nitrogen, so that a compressed gas is generated, wherein the gas compressor (4) comprises: an inlet (4A) to receive the gas, and an outlet (4B) for the compressed gas, the hydrogen and nitrogen blending system further comprises: a separator (5) fluidly coupled with to the outlet (4B) of the gas compressor (4) and configured to receive the compressed gas and to separate hydrogen and nitrogen from the compressed gas, and an energy recovery unit (7) configured to recover energy from the nitrogen separated by the separator (5).

2. The hydrogen and nitrogen blending system according to claim 1, wherein the separator (5) comprises an inlet (5 A) to receive the compressed gas, as well as a first outlet (5B) for the hydrogen separated from the gas and a second outlet (5C) for the nitrogen separated from the gas.

3. The hydrogen and nitrogen blending system according to claim 1 or 2, wherein the hydrogen and nitrogen blending system comprises a hydrogen storage unit (6) to store at least a portion of the hydrogen separated by the separator (5).

4. The hydrogen and nitrogen blending system according to any one of the preceding claims, wherein the energy recovery unit (7) comprises a gas expander to expand the nitrogen separated from the hydrogen by the separator (5).

5. The hydrogen and nitrogen blending system according to any one of claims 1-4, wherein the hydrogen and nitrogen blending system comprises: a hydrogen source (1) to deliver hydrogen, a nitrogen source (2) to deliver nitrogen, wherein the inlet (4A) of the gas compressor (4) is fluidly coupled with the hydrogen source-9-(1) and the nitrogen source (2), wherein the hydrogen and the nitrogen of the mixture of hydrogen and the nitrogen are the hydrogen delivered from the hydrogen source (1) and the nitrogen delivered from the nitrogen source (2), respectively.

6. The hydrogen and nitrogen blending system according to any one of claims 1-4, wherein the hydrogen and nitrogen blending system comprises a gas source (3) to deliver the gas, and the inlet (4A) of the gas compressor (4) is fluidly coupled with the gas source (3).

7. The hydrogen and nitrogen blending system according to any one of the preceding claims, wherein the gas compressor (4) is a multi-stage compressor.

8. A method (1000) of operating a hydrogen and nitrogen blending system according to any one of the preceding claims, the method (1000) comprising the following steps:- compressing (100) a gas comprising a mixture of hydrogen and nitrogen by means of the gas compressor (4);- receiving (101), at the separator (5), from the compressor (4) the gas comprising a mixture of hydrogen and nitrogen;- separating (102) hydrogen and nitrogen from the gas by the separator (5); and- recovering (104) energy from the nitrogen separated by the separator (5) in an energy recovery unit (7).

9. The method (1000) according to claim 8, wherein the method comprises the step of storing (103) at least a portion of the hydrogen separated by the separator (5) in a hydrogen storage unit (6).

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